Surface Technology for Automotive Engineering

Surface technology for automotive engineering

K. Bewilogua a, G. Brauer a, A. Dietz a, J. Gabler a, G. Goch (1)b, B. Karpuschewski (1)c,*, B. Szyszka a

a Fraunhofer-Institute for Surface Engineering and Thin Films (IST), Braunschweig, Germanyb Bremen Institute for Metrology, Automation and Quality Science (BIMAQ), Germanyc Institute for Manufacturing Technology and Quality Management (IFQ), University of Magdeburg, Universitaetsplatz 2, 39106 Magdeburg, Germany

CIRP Annals - Manufacturing Technology 58 (2009) 608–627

A R T I C L E I N F O

Keywords:

Coating

Chemical vapour deposition (CVD)

Physical vapour deposition (PVD)

A B S T R A C T

The presented paper describes the role of surface technologies in the automotive industry. Various hard

coatings like nitrides, diamond and cBN are used on tools for the manufacturing process. Due to their high

hardness and low coefficient of friction, diamond-like carbon films will be indispensable for engine and

power train components. The improvement of automotive glazings by optimization of optical and

thermal properties of the glass is an ongoing development task. Coatings with switchable transmission,

thin film solar cells as self-cleaning and self-healing surfaces will be features in the car of the future.

Various atmospheric pressure and low pressure deposition processes are available. In this paper low

pressure plasma and electrochemical deposition are in focus.

� 2009 CIRP.

Contents lists available at ScienceDirect

CIRP Annals - Manufacturing Technology

journal homepage: http: / /ees.elsevier.com/cirp/default .asp

1. Introduction

In general surfaces are not perfect. However, in our daily life wecommunicate with objects mainly through their surfaces. Surfaceand coating technologies on one hand improve existing materialsand products; on the other hand they are indispensable for therealization of innovative products based on particular properties ofthin films.

Tailored coatings allow the adjustment of

� m

00

do

echanical (wear, friction);
� c hemical (corrosion, permeation, temperature insulation, bio-
compatibility, wettability);
� e lectrical (conductivity); � o ptical (transmission, reflection, absorption, colour).
properties of surfaces.Surface technology means modification, structuring or coating

of materials and components. In case of coatings, one maydistinguish between ‘‘thick’’ and ‘‘thin’’ film technology. We shalltalk about thick film technology for film thicknesses above 10 mmand thin film technology for film thicknesses between 0.1 nm and10 mm. However, this division is not fixed.

According to the ‘‘Organisation Internationale des Construc-teurs d’Automobiles’’ (OICA) in 2007 around 53 million cars and 20million commercial vehicles have been produced. The automotiveindustry is one of the most important users of modern surfacetechnologies.

Besides lacquerfor decoration andlongtermcorrosion protection,tribological coatings on drive components or various functionalcoatings on car glazing are the most popular applications. Hardcoatings with low coefficients of friction are an effective way toreduce wear and friction as well as lubricants. Coatings on glass may

* Corresponding author.

07-8506/$ – see front matter � 2009 CIRP.

i:10.1016/j.cirp.2009.09.001

reduce disturbing reflections or minimize the thermal load to thepassenger compartment. Thin films also will play a decisive roll formany kinds of novel sensors adding more intelligence to the car.

This holds for the components themselves as well as for thetools to manufacture them. Fig. 1 shows typical applications forfunctional coatings in automotive engineering.

A huge variety of basic processes and related modificationsexists for the deposition of coatings or modification (e.g. hard-ening) of surfaces. The most important are lacquering, electro-chemical deposition, thermal spraying, and low pressure plasmabased processes like physical vapour deposition (PVD), plasmaassisted chemical vapour deposition (PACVD) or plasma diffusiontreatment. In the frame of this keynote paper the authors want tofocus on electrochemical and plasma processes as well as a few keyapplications.

The paper concludes with some visions for the car of the future.

2. Coatings on tools for automotive engineering

2.1. Recent developments in coating systems for cutting tools

Increasing demands on production processes lead to the need ofcontinuous improvement in cutting technologies. Especially due tothe need for continuously improving the productivity, decreasing theprocessing costs and increasing demands on products, machiningoperations like hard machining, dry machining, high speed machin-ing and precision machining have experienced significant growth,while continuously imposing higher stresses on tools. Advancedcoating systems are aimed at improving the tool wear behavioursignificantly and to enhance the tool performance [60]. Thus therequirements on the wear resistance of cutting tools are essential.Hard coatings, e.g. TiN, TiC, and Al2O3 deposited on cutting tools havebeen used since 1960 to increase tool lifetime [22]. Current trends inthe tool industry are moving away from conventional standard toolsinto the direction of high quality specific tools. Today manufacturers

http://www.sciencedirect.com/science/journal/00078506

http://dx.doi.org/10.1016/j.cirp.2009.09.001

Fig. 1. Examples for the application of surface technologies in a modern car.

Fig. 2. Influence of coatings on wear mechanisms and contact conditions.

K. Bewilogua et al. / CIRP Annals - Manufacturing Technology 58 (2009) 608–627 609

and end users focus on configuring individual coatings and coatedtools[50].However, duetotherisingvariabilityof coatingsystemsforcutting tools, a careful selection of a suitable coating system isbecoming more important.

In this chapter recent developments in cutting tool coatingsystems, like cubic boron nitride (cBN) based coatings, super-nitride coatings, diamond coatings and nanocomposite coatings,are documented.

2.2. Properties of coatings

In order to select or develop a suitable tool coating, it isnecessary to identify the primary wear mechanisms inherent in thespecific machining task. The ability of a coating system to reducewear sufficiently is the criterion for choosing it [103]. Wear oncutting tools during machining is caused by a complex interactionof surface effects like adhesion, abrasion, diffusion and tribo-oxidation or volume effects like crack initiation, scoring and plasticdeformation (Fig. 2). Tool coatings are used to increase wearresistance and to vary contact conditions to the effect that wear ofthe tool is reduced [106].

Besides the properties of the coating itself, interactionsbetween coating and substrate, especially the bonding, are veryimportant for the tribological and wear behaviour of coated tools.

Therefore different methods for pre-treatment of the substrate,for example micro-blasting, brushing, water peening or magneto-abrasive machining after grinding, can be applied to improvecoating substrate adhesion [18,42,97,172].

With the trend towards individual coated tools it is becomingincreasingly important to treat the tool manufacturing as acomplex system. This system is influenced by many differentprocess parameters which have to be optimized for the specialcoating process and machining task.

2.3. Recent cutting tool coating systems

2.3.1. Cubic boron nitride

Cubic boron nitride (cBN) is a material with great technologicalimportance through its high hardness and chemical inertnessagainst ferrous materials.

Thanks to the ability to coat tools with complex geometries,such as chip-breakers on inserts, cBN based coatings on carbideinserts are complementary to widely used polycrystalline cubicboron nitride (PCBN) compact tools for finish hard turningapplications [91].

Various physical and plasma assisted chemical vapour deposi-tion processes (PVD, PACVD) have succeeded in cBN filmdeposition as reviewed, e.g. by Bello et al. [10]. However, mostlythe achievable thickness range of cBN films on silicon substrateswas limited to <500 nm. This thickness limit is mainly caused byan enormous residual intrinsic compressive stress (up to 20 GPa)and a pronounced sensitivity to humid air. In the last few yearsthere has been impressive progress in the field of thick (>1 mm)cBN coatings. Some research groups succeeded in deposition ofthicker cBN, up to 20 mm [10,99,175,192]. In spite of theimpressive results reported and several techniques which weredescribed for deposition of thicker cBN films, no successful transferof cBN deposition processes to industrial coating machines couldbe realized so far.

Thick cBN coatings (up to 2 mm) were deposited as top layers oncemented carbide cutting inserts pre-coated with TiAlN [99,136].The deposition processes were done by reactive sputtering using aboron carbide target. In hard turning tests the cBN layers depositedon the TiAlN-interlayers resulted in lifetime enhancement,

Fig. 6. Microstructure of Ti46Al54N coating and nanostructured supernitride (SNTR)

one [51].

Fig. 3. A comparison of tool wear between TiAl and TiAlN + cBN top layer coated

cemented carbide cutting inserts for different cutting speeds [99].

Fig. 5. Phase diagram of the metastable system TiN–AlN [51].

K. Bewilogua et al. / CIRP Annals - Manufacturing Technology 58 (2009) 608–627610

especially at higher cutting speeds compared to a TiAlN referencecoating (Fig. 3). However, in hard milling tests the performance ofTiAlN could not be achieved by cBN coating system [99].

Because of the difficulty in terms of depositing thicker layersfrom vapour phase, a hybrid deposition process was developed,which allows deposition of a thick (5–20 mm) cBN–TiN compositecoating using electrostatic spray coating (ESC) and chemicalvapour infiltration (CVI) [118]. Before this deposition processstarts, the tool inserts were cleaned by washing them in a milddetergent solution, rinsing with deionised water and dried withhot air. Subsequently the electrostatic spray process (ESC) iscarried out, used to deposit a uniform layer (Fig. 4, left) of CBNparticles (�2 mm) [146].

These cBN particles are only loosely bound (by static forces) toeach other and to the substrate and built up pores (Fig. 4, middle)[146]. These built up pores are important for the following CVIprocess. At this point, the pores were infiltrated with TiN as shownin the right picture in Fig. 4. The CVI process is a spin-off ofchemical vapour deposition (CVD) and it is used to convert the ESCcoated particulate porous surface into a hard composite coatingincluding strong bonding with the substrate surface [146].

More et al. [126] investigated the tool wear performance ofcBN–TiN coated WC–Co in comparison to PCBN compact inserts inturning AlSi 4340 hardened steel. Although the tool life ofapproximately 18–20 min per cutting edge of the cBN carbideinserts is lower compared to the PCBN tool with a produced tool lifeof 32 min, the cBN–TiN coated carbide tools are considered to be animportant complement to PCBN compact tools for hard turningapplications. This conclusion is based on the investigation of totalmachining costs per part for both variants. It indicates that thesavings in machining costs using cBN–TiN coated inserts isbetween 12% and 30%.

A critical assessment of both vapour phase and hybrid processeswas recently given by Richter [143].

2.3.2. Supernitrides

One of the most promising state-of-the-art coatings is still themetastable solid solution phase (Ti,Al)N in cubic B1 structure.These coatings offer a superior oxidation and chemical resistanceand hardness as compared to conventional TiN or Ti(C,N) [50].

Fig. 4. Cross-section of ESC deposited CBN, pores in the c

With increasing aluminium content the oxidation resistance of(Ti,Al)N coatings increases, however a barrier is set to the PVDprocess technology by the deposition of insulating films at a filmcomposition of approximately 65–67 mol% AIN (Fig. 5) [51].

Besides the improved mechanical properties, further significantcoating parameters for their effective application on cutting toolsespecially at elevated cutting temperatures are the film oxidationresistance and thermal conductivity [48].

Erkens et al. [51] investigated the cutting performance of thesupernitride coatings. Therefore they compared a characteristic(Ti,Al)N based supernitride variant, the SNTR (with AlN content67 mol%) deposited on cemented carbide inserts and cuttinginserts, which were coated with using the same parameters withan effective state-of-the-art (Ti46Al54)N wear protective film.

The microstructure of both coatings is illustrated in Fig. 6. Thestructure of the supernitride is distinguished by a more finegrained, nanocrystalline structure in comparison to the conven-tional coating.

The wear performance in milling of the supernitride SNTR can beobserved in Fig. 7.

It is demonstrated that the nanostructure and the increased AlNcontent act more positively on the behaviour of the supernitrideSNTR coating at higher cutting speeds [51].

2.4. CVD diamond

Due to its extreme hardness and resistance to wear, diamond isthe ideal coating material for cutting tools, designed for ‘‘difficult-

BN layer and cross section of cBN–TiN coating [92].

Fig. 9. Flank wear in machining Al–20 wt% SiC composite [89].

Fig. 7. Cutting performance of the applied coatings in milling 42CrMo4-hardened

steel [51].

Fig. 8. Surface structure of micro- (left) and nanocrystalline (right) CVD-diamond

layer [5].


to-machine’’ materials, like carbon fibre-reinforced plastics,graphite, wood based materials and metal matrix composites(MMC). Three industrial applications have been established up tonow, where CVD diamond coated tools demonstrate their potentialin series production: When a large graphite electrode for EDM isproduced, no tool change can be accepted during the machining ofthe workpiece since this would lead to a mark on the surface due tothe larger tool diameter of the new tool. Diamond coated endmills[28,105] have lifetimes when machining graphite of 15 h and moreand thus enable the production of these large electrodes. In theproduction of printed circuit boards (PCBs) diamond coated micro-routers prolong the tool life significantly, save time for changingtools and thus increase the productivity of this manufacturing step,which is mostly the bottle-neck in the production of PCBs [109].For fibre-reinforced plastic parts, which are increasingly used inaircraft design, complex shaped shaft mills are used advanta-geously [83]. With these tools the strong requirements fordelamination and dimension tolerances can be met compared tosimple shaped tools with massive diamond (PCD) inserts.

Several chemical vapour deposition (CVD) processes have beendeveloped for depositing diamond films on cutting tools. Hotfilament CVD (HFCVD), microwave plasma CVD (MWPACVD) andplasma arc CVD are the most widespread techniques used for thinfilm deposition of diamond on cemented carbide cutting tools[148,180].

Due to the effect of Co on favouring the formation of C-sp2 andthe resulting limited adhesion of the coating, the cemented carbidesubstrate surface has to be treated before coating. Therefore achemical etching can dissolve Co particles at the surface andincrease substrate roughness. Alternatively interlayer systems arebeing developed to prevent the diffusion of Co and the resultingcatalyzed formation of graphite [27].

Uhlmann et al. found that the performance of diamond coatedtools depends strongly on the properties of tungsten carbidesubstrates as well as on the pre-treatment [174]. During highlyfrequent mechanical load, the diamond coating adheres better, if ahigher hardness, a lower cobalt-content of the substrate and alower surface roughness are given. A deeper etching during thepre-treatment in order to remove cobalt from the sub-surface aswell as a thicker layer also have a positive influence on theadherence of the layers. The influence of the layer morphologycould not be proven clearly in that case. The friction behaviour ofdiamond coated tungsten carbide tools is influenced by the surfacecondition and the substrate properties only to a small degree.

Hu et al. [89] studied the properties of nanocrystalline diamond(NCD), produced by MWPACVD, in comparison with HFCVDmicrocrystalline coatings and PCD tools. Fig. 8 shows the surfacesof nanocrystalline and microcrystalline diamond coatings. It is

clear that a nanocrystalline coating has a much smoother surfacecompared to a microcrystalline diamond coating because of theultrafine crystallites.

In Fig. 9 the flank wear development is demonstrated inmachining Al–20 wt% SiC composite.

The result of the cutting performance of the nanocrystalline toolis comparable to the PCD one and much better than themicrocrystalline tool. The stronger built-up of the workpiecematerial on the rough, microcrystalline diamond layer leads tostronger adhesive wear and can be regarded as the reason for themuch shorter tool life compared to the smooth nanocrystallinediamond coating.

Further researches [3] in turning EDM graphite electrodes withmicro- and nanocrystalline CVD diamond coated Si3N4 ceramicinserts tools showed the potential of both coating types and theceramic tool material for this special machining task, with anachieved machined length of at least 10 km per tool edge. Nodelamination of diamond film was remarkable due to the use ofsilicon nitride ceramic as substrate for the coating.

2.4.1. Nanocomposites

The development of nanocomposites provides enormouspotential for the improvement of coatings. The structure of TiAlNbased nanocomposite films depends on deposition of very differentkinds of materials, the components (like Ti, Al, Cr in the first groupand Si in the other) are not mixed completely, and 2 phases arecreated. The nanocrystalline TiAlN- or AlCrN-grains are embeddedin an amorphous Si3N4-matrix (Fig. 10) [35].

The industrial and economical property for deposition ofnanocomposites is provided by the advanced LARC1 and CERC1

technology (Lateral Rotating Cathodes and CEntral RotatingCathodes) [36].

The main advantages of these novel coatings are the higherhardness compared to other conventional coatings and especiallythe enormous improvement of heat resistance. The spinodalsegregation and the resulting loss of hardness tend to appear muchlater than with non-nanocomposites (Fig. 11) [35].

The comparison of the lifetime of coated tapping tools isillustrated in Fig. 12. At the standard machining rate of 25 m/minthe performance of the nanocomposites is only a little better thanthe best TiAlCN coating and about two-times better than the TiCN

Fig. 10. Nanocomposite structure.

Fig. 12. Comparison of the lifetime of tools for dry tapping [182].

Fig. 11. Influence of nanocomposite structure on spinodal segregation [36,86].

Fig. 14. Performance improvement of nanocomposite coating in gear hobbing.

Fig. 13. Comparison of coatings on drills made of cemented carbide (drilling

GGG40) [182].


coating. However at a high cutting speed, the nanocomposites loseonly about 12% of the lifetime whereas TiAlCN coatings lose morethan 50% and the other both coatings performed poorly.

In this case the excellent performance of the nanocompositecoatings arises not only from the higher hardness and oxidationresistance, but also from the smoother surface [182]. Fig. 13 showsthe comparison of the lifetime in drilling of cast iron GGG40. Thelifetime of nanocomposite coated tools is slightly higher than thatwith state-of-the-art (Ti1�xAlx)N ones, although the applied

surface speed and feed-rate are significantly higher. The facilityof faster machining results in an increase of the productivity byabout 56% [182].

Nanocomposite coatings are also expected to be capable for usein gear hobbing processes. These operations are characterized bydynamical load and discontinuous wear attack on the coated tool.Therefore the coating system must satisfy special requirements.Karpuschewski et al. studied the performance of state-of-the-artcoatings compared with newly developed AlCrN based nanocom-posite coating in gear hobbing [96]. The resulting improvement isshown in Fig. 14.

The experimental tests were carried out using PM-HSS and HMtools. In both cases the nanocomposite coating performed betterthan the conventional coating. A proper improvement could beachieved in the case of using HM tools.

Nanocomposites will play a major role in future developmentsto enhance performance of cutting tools, especially for dry cuttingoperations, due to their hardness at elevated temperatures [37].

2.5. Coatings for forming tools

Forming tools, e.g. for punching or deep drawing, are widelyused in the automotive industry. Actual developments in formingprocesses are focussed on light materials like Ti, Al or Mg. For manyyears it has been known that chromium nitride CrN or titaniumbased coatings like TiN, TiCN or TiB2, prepared both by PVD as wellas by CVD techniques, can considerably increase the tool lifetime[87,85]. Modern coating designs for forming tools show a tendencytowards multilayer composites. Such composites, e.g. can consistof hard base layers covered by relatively soft low friction top layerslike MoS2 or amorphous carbon [85].

Diamond-like carbon (DLC), known in several modificationswith a large spread of properties, is an attractive coating materialfor forming tools [169]. However, for many years the applicabilityof DLC coated forming tools was limited because the achievablecoating adhesion was insufficient under real high load operationconditions. Recently, a considerable improvement of the DLCadhesion has been realized by preparing special interlayer systemsdesigned for high shear stress applications [186,187].

There the complete optimized coating system consists of thefollowing single layers:

� fi
rst chromium layer (Cr); � c hromium nitride (CrN); � s econd Cr layer; � tu ngsten containing amorphous hydrogenated carbon (a-C:H:W
or W-DLC).

The corresponding coatings have been used in several industrialapplications [186].

Fig. 15. Abrasive wear rates and hardness of a-C:H:W and a-C:H coatings prepared

by PACVD (r.f.: radio frequency excited plasma, m.f.: mid-frequency excited

plasma) and C-DLC (see preparation of DLC based coatings).


Further improvements of the tool performance can be expectedif the tools can be treated in a plasma diffusion process, e.g.nitriding, before starting the coating deposition.

The continuous developments in coating technology for cuttingand forming tools allow fulfilling the increasing demands ofindustrial applications with regards to economical and ecologicallybenign processes. It is considered that in the future the coatingtechnology will be furthermore an important aspect for enhance-ments of cutting tool performance related to the enclosingtreatment and research of the coating system with all itsinfluencing parameters.

3. Coatings for engine and power train components

3.1. Coating materials and applications

Today several components of engines and power trains inautomobiles are coated with wear and friction-reducingmaterials to increase their lifetime, reduce fuel consumptionand prevent corrosion [183]. Since more than 10 years for thebase materials of these components there is an increasing trendto lightweight materials like aluminium or magnesium [135].Here aluminium alloy engine blocks should be mentioned[6,117].

It is noteworthy that besides coating processes also othersurface treatments like nitriding, especially plasma nitriding, canconsiderably improve the performance of automobile components[113]. The potential of plasma nitriding will be considered moredetailed below.

Examples for coatings used for automotive applications are:Piston rings—coated with hard chrome, deposited by galvanic

processes, with chromium nitride, prepared by PVD techniques[183], mostly arc evaporation, or with a metal matrix composite(MMC) produced by thermal spray techniques [52]. Typical coatingthicknesses are in the range of some 10–100 mm.

Cylinder bores of aluminium cast engine blocks—coatingsconsisting of carbon steel partly reinforced by ceramic particles,prepared by thermal spraying [6,113,17]. Older variants of suchcoatings are nickel based composites or hard chrome [117].

Crankshaft bearings—typical materials are Al–Sn, Al–Sn–Bialloys or steel-bronze. Brewe [19] presented an assessment ofseveral slider bearing materials considering different operationconditions.

Ball pivots—a significant reduction of corrosion combined withimproved wear behaviour and lower friction coefficients could beachieved by combining plasma nitriding and oxidation [183].

Injector needles in diesel engines—coated with diamond-likecarbon (DLC) coatings [173].

Just the last mentioned DLC based coatings became more andmore important for the friction and wear reduction of severalautomobile components. In the last years, DLC based coatings wereat least in discussion also as candidates for all other abovementioned application fields.

The term DLC describes a coating material class covering abroad range of physical and chemical properties. Well definedcombinations of coating properties can be adjusted using differentdeposition processes and parameters.

Due to the extremely high pressures of 2000 bar and more indiesel injection systems [173], DLC coatings are indispensable forthese components.

Other applications of DLC coatings in serial car productionconcern tappets and piston pins. Furthermore DLC coatings will beused nearly in 100% of high performance applications in racing carengines, e.g. on camshafts and valves [178].

The annual market value of DLC coated components has beencontinuously increasing since the last decade of the last centurywith the trend towards 600 Ms in the next few years [178].

In the following sections classification and properties, prepara-tion techniques and applications of DLC based coatings shall bediscussed in detail.

3.2. DLC based coatings

3.2.1. Classification and properties of DLC coatings

Diamond-like carbon (DLC) coatings are well known for theirhigh hardness and wear resistance as well as low friction coefficientsand sometimes low surface energies. Commonly a distinction isdrawn between hydrogen free (a-C or ta-C) and hydrogen containing(a-C:H) films. Both types can be modified by incorporation ofadditional elements like metals (a-C:H:Me) or non-metallicelements (a-C:H:X—X: additional elements). Other properties ofDLC based coatings which could be rather interesting for technicalapplications are: a broad range of electrical resistivity, transparencyin the infrared spectral range, chemical inertness or variable wettingbehaviour (corresponding to different surface energies).

Especially a-C:H and metal containing a-C:H:Me coatings aretoday established in industrial practise, mainly for automotiveapplications.

The combinations of excellent mechanical and tribologicalproperties have been well known for several years. Low frictioncoefficients (m � 0.2 against steel under dry, lubricant freeconditions) were measured for a-C:H and also for metal-containingamorphous hydrogenated diamond-like carbon films (a-C:H:Me orMe-DLC) [46,102]. In the following discussion the abbreviations a-C:H and a-C:H:Me shall be used.

In the last 10 years a-C:H coatings displaced the metalcontaining a-C:H:Me coatings more and more in the field ofhighly stressed automotive components. The background of thissubstitution is that the metal free a-C:H is considerably harder andmore wear resistant than a-C:H:Me [173,13]. Fig. 15 shows thisrelation for tungsten containing a-C:H:W and three different a-C:Hcoatings.

Furthermore, adhesion problems of a-C:H coatings limitingtheir reliable application, could be resolved even in industrialscales by appropriate interlayer systems between substrates and a-C:H top coating (e.g. [79]). Hydrogen free tetrahedral amorphouscarbon (ta-C) films with a dominating content of sp3 bondedcarbon atoms (>50%) can be still harder (>50 GPa, [133]) than a-C:H (see Fig. 15). Recently large scale laser-arc depositiontechniques for ta-C were developed and transferred to industrialbatch coaters [151]. Such ta-C coatings should be potentialcandidates for highly loaded automobile components.

Very interesting and promising coatings properties can beachieved by modifying with non-metal elements: a-C:H: X (X: Si,O, F, N). Silicon containing a-C:H:Si film are known to have stilllower friction coefficients than a-C:H [132]. Films containing bothsilicon and oxygen (a-C:H:Si:O) are characterized by rather lowsurface energies which are comparable to those of Teflon1 [72].Low surface energies lead to a decreasing wettability and to alower susceptibility to adhesion of materials, e.g. of powders onpressing tools. Fig. 16 shows the water contact angles and thesurface energies for different modified DLC coatings. Compared to‘‘pure’’ a-C:H both lower and higher surface energies can be

Fig. 16. Water contact angles and surface energies (polar and disperse components

are shown) for a-C:H and modified a-C:H:X coatings as well as for PTFE (Teflon1) as

reference.


realized. However, an optimization of one property mostly leads toa deterioration of other properties. Thus highly hydrophobic filmscommonly have a relatively low wear resistance.

To illustrate this, Table 1 gives an overview on characteristicvalues for plastic hardness (HUplast/GPa), abrasive wear rate (wr/10�15 m3/Nm), water contact angle (WCA/18) and surface energy(SE/mN/m) of different amorphous carbon films and of Teflon1 asreference.

To overcome this drawback, multilayer coatings were preparedto combine the best properties of single layers. For example acombination of a-C:H and a-C:H:Si allows to synthesize films withboth extremely low friction and low wear rates [123].

In an ambient atmosphere under dry, lubricant free conditionsnearly all amorphous carbon films have low friction coefficients�0.2 against steel. An exception is a-C:H:Si:O (see Table 1).

However, the friction behaviour under dry conditions does notallow predictions on typical machine operation conditions in alubricated state. On the other hand, low dry friction coefficientscan prevent scuffing if the lubricant is insufficient or fails. Frictionunder lubricated conditions is a complex process depending on thetype of lubricant, additives, coating type, operating temperatureand contact conditions. Generally, compared to steel, the most DLCbased coatings reduce the friction coefficients under lubricatedconditions [137,40,150].

More details on a general classification and nomenclature ofcarbon based coatings can be found in a recently developedguideline [180].

3.2.2. Preparation of DLC based coatings

The most widely applied method to deposit a-C:H films is basedon the glow discharge of hydrocarbon gases with substrateelectrodes excited by radio frequency (r.f.—13.56 MHz) or mediumfrequency (m.f.—some 10 to some 100 kHz) power [80]. In the m.f.range both harmonic a.c. and pulsed d.c. voltages have beensuccessfully applied. These techniques often will be named asPACVD (plasma assisted chemical vapour deposition). Beside purea-C:H also modified a-C:H:X coatings (X: Si, O, F or other elements)normally will be prepared by PACVD methods. Examples for thedifferent precursors to be used are:

� a

TaSo

-C:H: methane (CH4) or acetylene (C2H2);
� a -C:H:Si: tetramethylsilane TMS (SiC4H12) (+CH4 to vary the Si
content);
� a -C:H:Si:O: hexamethyldisiloxane HMDSO (Si2OC6H18).
ble 1me essential properties of different DLC based coatings and of Teflon1. Outstanding

Hardness [GPa] Friction coeff. m vs. steel

(ambient air)

a-C:H 25–35 0.15–0.2

a-C:H:Sia 20 <0.1

a-C:H:Si:O 8–10 0.4–0.6

a-C:H:W 15–20 0.2

Teflon1 <0.5 0.1a Si/C�0.2.

Metal containing a-C:H:Me coatings are prepared mostly byreactive d.c. magnetron sputtering in industrial batch coaters[79,161] or in multi-chamber in-line machines [76]. Sputteringbelongs to the so called PVD (physical vapour deposition)techniques (see chapter 6). The used targets consist of metal ormetal carbide and the working gas is an argon–hydrocarbonmixture [161,14]. The magnetron sputter technique has highpotential for scale-up, for deposition of complex coating systemslike multilayer films and also for realization of in-line depositionprocesses. Using graphite instead of metal targets, also metal freea-C:H coatings can be prepared by reactive d.c. magnetronsputtering [13]. In order to emphasize the similarity of thedeposition process to that for a-C:H:Me the name C-DLC wasintroduced for this a-C:H coating material.

Working with well defined special process parameters in anunbalanced magnetron (UBM) mode causing high plasma den-sities, very hard (up to 50 GPa, compare with data in Fig. 15) C-DLCcoatings can be deposited [129]. The structural reason for thesehigh hardness values obviously is the relatively low hydrogencontent (near 10 at%) compared to about 15 at% for ‘‘standard’’ a-C:H like cognizable from Fig. 17.

In serial productions of a-C:H coatings, e.g. for automotivecomponents, today in many cases a hybrid process consisting of asputter deposition of an adhesion improving metal based layer (Cr,CrN) and a PACVD process (m.f.) for the a-C:H top layer is used [79].

3.2.3. Potential future application fields of DLC based coatings

The promising properties of DLC coatings have led to acontinuously increasing number of application areas for machineand engine components [121,113,173,178] as well as for formingand cutting tools [121,43]. The different modifications of DLCbased coatings result in a broad spectrum of properties (seeTable 1). Gradient or multilayer arrangements combining thedifferent layer materials allow realizing even a still wider range ofcoating properties.

Except for the extraordinary coating properties it is importantthat diamond-like carbon can be deposited at low substratetemperatures (<200 8C), e.g. on temperature sensitive materialslike ball bearing steel or even plastics.

On the other hand, if the base materials to be coated have astable microstructure up to higher temperatures like, e.g. highspeed or cold working steels, a plasma nitriding process or a duplexprocess (plasma nitriding combined with subsequent coatingdeposition) can considerably improve the tribological properties ofautomobile components [183,113]. In the case of DLC based topcoatings duplex processes result in higher surface hardness, lowerfriction coefficients and particularly improved adhesion [125,59].

Furthermore, the following application perspectives, today stillin a development phase, should be noted:

� G

p

ears: DLC coatings of gear surfaces seem to be very promisingwith respect to further reduction of friction and to operationunder lubrication loss conditions. However, this application isnot widely established so far [178]. On the other hand there aresome research results indicating a potential benefit. Murakawaet al. [130] revealed that WC/C (a-C:H:W) coatings enlarged thelifetime of test gears three times. Furthermore, it was reported bythese authors that a micro-shot peening pre-treatment processmodified the ground surface and increased the lifetime of the

roperties are highlighted.

Abrasive wear

[�10�15 m3/Nm]

Water contact

angle [8]Surface energy

[mN/m]

0.5–1 70–75 40

2–4 75–80 38

10–15 95–105 24

1–4 65–70 42

� 110–120 19

Fig. 19. Radial bearing ring with DLC force sensor structures (for details see [16]).

Fig. 18. Part of tire mold coated with a anti-sticking a-C:H:Si:O coating.

Fig. 17. Hardness of C-DLC (a-C:H) coatings vs. hydrogen content, measured for

samples prepared in two different plants both using reactive sputter techniques

with graphite targets. As reference the field typical for a-C:H from PACVD processes

is marked.


coated gears. Yao et al. [194] concluded from tests with coatedand uncoated rollers that coatings (a-C:H:W) can only enhancethe durability if both partners in the tribosystem are coated. Theeffects described here obviously are related to relatively rough,not polished gear surfaces. Indeed the polishing of gearcomponents is clearly too expensive to be done in serialproduction.
� L ubricated components: So called lubricant or oil pockets,
consisting of dimples in the surfaces of friction partners, canconsiderably influence the behaviour of lubricated tribologicalsystems of forming tools [7] or components [107]. It is to expectthat combinations of such topographically modified surfaceswith suitable coatings, e.g. a DLC modification, could furtherreduce friction losses in engine components. Today, differenttechniques for modifications of surface topographies are knownand will be widely used [21].
� A nti-sticking coatings: As described above, modified a-C:H
coatings like a-C:H:Si:O are characterized by low surfaceenergies causing low wettability with liquids and low stickingof various solid materials [81]. This property could be used toreduce the sticking of carbon-particulate matter, e.g. on intakevalves of engines. Fig. 18 shows a car tire molding tool where a-C:H:Si:O coatings were found to have a potential to reduce thetire material deposition, improve demolding and cleaningbehaviour.
� T he anti-sticking and low wetting effect can be considerably
enhanced by combining surface roughness in micro- andnanometer length scales with hydrophobic top layers [54,101]like the well-known lotus-effect in nature. However, thesesuper-hydrophobic surface structures seem to be mechanicallyless stable than smooth surfaces coated, e.g. with a-C:H:Si:O or asimilar hydrophobic coating.
� T hin film sensors: In the recent years DLC based coatings became
more and more interesting because of their piezoresistiveproperties. Under mechanical pressure the resistance of DLCcoatings decreases reproducibly. This allows the use of suchcoatings as force sensors, e.g. on washers or bearings [16]. Fig. 19

shows a radial bearing with DLC force sensors. One obstacle onthe way to a reliable operation in bearings seems to be that theresistivity of these sensors depends not only on the force, but alsoon the temperature [16].

Before introducing such technical solutions into a broadapplication many problems need to be solved, as excellentlysummarized by Lampe et al. [113] generally for the plasma surfaceengineering in automotive industry. As examples the long time forscale up processes to industrial dimensions, a high reliability, thecost effectiveness, the available production capacity and the patentsituation should be mentioned.

4. Coatings for automotive glazing, lighting and informationdisplay

4.1. Automotive glazing

4.1.1. Recent developments in coatings for automotive glazing

Automotive glazings are multifunctional devices [115]. Theyprotect against wind, cold and rain and also against thermal loadfrom the sun and environmental noise. Comfort and safetyfunctions such as sun-control [53], deicing [71], antireflex andeasy-to-clean properties [74] are realized by functional coatings[120,166] which are deposited using advanced thin film technol-ogies.

Coatings are applied as soft or hard coatings. Soft coatings arebased on thin metal films embedded in dielectric layers for opticalreasons. These soft and sensitive stacks have to be protected andthus, they are integrated in laminated glazings.

Hard coatings on the other hand consist of more robust ceramicmaterials or thicker metal films. They withstand mechanical wearand corrosive attack to a certain extent and can be applied on theinside or outside of the glazing.

Prominent examples for outside coatings are hydrophobic easy-to-clean coatings [74] for enhanced optical performance whiledriving in rain. The use of light weight complex shapedpolycarbonate glazings will be possible with appropriate UVprotective [147] anti-scratch coatings [152].

These examples are just the starting point for future develop-ments. Future car generations will be equipped with transparent[144] or head-up displays [165,179] in order to magnify trafficsigns and other critical events according to eye tracking systems.

Fig. 20. Strategies for sun-control windshield manufacture, e.g. coating on glass or

lamination of coated PET (left) and layout of double silver sun-control coatings

(right) [56].


Smart coatings will be used to adjust the transmittance of theglazing to minimize the heat load [66] and to protect the driversand passengers privacy.

4.1.2. Properties of coatings on automotive glass

There are four well known factors which disturb the driversvision and which cause severe discomfort: (i) light scattering fromwater droplets during rainy weather, (ii) light reflection from thedashboard, (iii) light reflection from the mirrors and (iv) thethermal overheat due to sun load [84]. Modern automotiveglazings make use of coated glass in order to handle theseproblems.

The most important coatings on automotive glass are sun-control coatings for laminated windshields. They are depositedeither on the curved glass or on the flat glass prior to glass bendingor on the polymeric web prior to lamination. The layout of thecoating is similar for all those cases as shown in Fig. 20. It containstwo thin silver layers embedded in antireflective dielectric layers.These coatings exhibit more than 75% transmittance in the visiblerange while the infrared part of the sun spectrum is blocked, asshown in Fig. 21. Compared to conventional tinted glass, decreaseof maximum interior temperature of more than 11 8C from morethan 100 to 89 8C is achieved for extreme climate tests [104] andmore important, the time needed for the air conditioning to reachcomfortable temperature levels is decreased by 40% [82]. Themarket penetration for these types of windshields is about 30% forcar production in Europe in 2002.

For single glass sun roofs and side or back windows, the conceptof lamination of insulator–metal–insulator stacks is not feasible.Dielectric layer stacks can be used for this application [164].Currently, however there are no products on the market utilizingthis technique.

Another important field of application is the control of surfaceenergy in order to achieve water repellant easy-to-clean layerswithout droplet formation during rainy weather. Organic hydro-

Fig. 21. Optical spectra of uncoated, tinted sun-control glass and double silver

coated sun control glass [55]. The sun spectrum for air mass 1.5 is also shown.

phobic layer systems exhibit lifetime of about 3 years on thewindshield [74]. Also hydrophilic layers are used to improve thedriver’s vision during rain. These coatings are applied on themirrors in order to spread the water film and to minimize thescatter [167]. The use of hydrophilic layers is a new field ofapplication compared to the use of water repelling hydrophobiccoatings, which are applied by wet chemical deposition [128].

Antireflective layer stacks are used to minimize the reflectionfrom the dashboard. Sufficient results have been obtained forglazings which have been coated only on the inner side of the glass.These windshields exhibit reflectance smaller than 10% at an angleof incidence of 608 [74]. UV protective TiO2:CeO2 films aredeposited by sol–gel coating on glass to minimize the interior UVload [127].

At night time, the driver’s vision is impaired due to intensereflection from the mirrors. This problem can be minimized bydielectric or metallic front side mirrors [62] in contrast to standardAg plated back side mirrors. The problem of image distortion byrain droplets can be solved using a photo induced hydrophilic TiO2

coating of the mirror surface [78]. Furthermore, switchableelectrochromic coatings are used for coating on inside and outsiderearview mirrors which are controlled by photodiodes [116].

4.1.3. Substitution of mineral glass by polycarbonate

Mineral glass has shown to be an excellent material forautomotive glazing due to its excellent optical performance, itslong term durability and low production costs. However, demandsfor light weight glazing, more complex shapes and the ability formore modular construction opened up the pathway for substitu-tion of mineral glass for automotive glazing by polycarbonate [11].

The polycarbonate allows weight reduction on the order of 50%,in contrast to PMMA, it is non-brittle and the parts can bemanufactured by injection molding. However, the scratch resis-tance is inferior to glass and the material is not UV stable. Bothproblems can be solved by coatings.

The first crucial point is the scratch resistance of the coatingwhich is measured with the Taber Abraser test. The stray light(Haze) level has to be smaller than 2% after 1000 revolutions of theTaber wheel. The second aspect is the UV stability which is checkedby outdoor exposure. For accelerated tests, the criteria are stabilityfor QUV-B for more than 1000 h and for xenon arc light for morethan 2250 h.

An early paper on that technology is the SAE report from 1993[77]. Several applications came up where wet coatings with aprimer film (�2 mm) and a thick silica filled organo-polysiloxanetop coat (�5 mm) were used. The haze level after Taber Abrasertesting is in the order of 7% after 100 revolutions compared tomineral glass with 2% after 1000 revolutions.

To compensate these drawbacks limiting the use of coated PC inthe rear part of automotive body behind the b-pillar, a new processtechnique has been developed in the 1990s. The plasma enhanceddeposition of transparent scratch protecting coatings by e-beamevaporation [98] or chemical vapour deposition (PACVD) [152]. Acommercial product with a plasma based hard coating in thethickness range of 4–6 mm and an underlying wet chemical UVblocker and primer was announced in 2003, the Exatec 500 [134]. Amodified version came up in 2006, the Exatec 900, where lifetimetests predict stability for more than 10 years. Degradation is due tofailure of the UV absorber and the maximum UV dose correlateswith the thickness of the UV absorber. The 10-year lifetime goal ismet with an UV absorber thickness of 65 mm deposited by wetchemical methods. The thickness of the plasma deposited abrasionresistant coating is in the order of 3 mm [147].

4.1.4. Potential for new developments

Functional coatings on the outer side: new functions such aslow emissivity outside coating to protect against condensation ofwater and ice formation in combination with fast cost effective fullsize heating units, durable easy-to-clean coatings and lowreflectance layers can be realized as soon as ultra durable

Fig. 22. Self-regenerating coating for long term hydrophobic coating based on

nanostructured surface which is covered with a hydrophobic agent supplied by the

underlying replenishment layer [142].


functional layers for outside coating are available. An importantaspect is the development of ultra durable conductive opticallayers with low emissivity. When the emissivity of the uncoatedglass of e = 84% is decreased to e < 20%, the radiation cooling isminimized to an extent that prevents the condensation of waterover night and thus, neither tarnishing of the glass nor iceformation occurs. Early work dates back to 1980s where SnO2:Ffilms deposited by spray pyrolysis had been investigated [75].However, the durability of the coating was not sufficient since thehigh roughness of the SnO2:F gave rise to extensive wear in theTaber test. The new technology of high power pulse magnetronsputtering opens up a pathway for solving that problem: crystal-line ITO (In2O3:Sn) films with thickness of 140 nm can be depositedon unheated glass substrates. This transparent and conductivecoating allows for glass bending and is extremely durable. Both thescratch and wear characteristics are improved with respect to thebare mineral glass [88].

A new concept for durable hydrophobicity are self-regeneratingwater repelling layers [142]: self-healing of super hydrophobicity isdue to a polymeric replenishment layer, which releases a voltatilewax-like polymer through a porous, nanostructured metal oxide topcoat, as shown in Fig. 22. Super hydrophobicity is due to themorphology of the metal oxide film plus the low surface energy ofthe wax film. A worn wax film recovers due to diffusion of polymerout of the reservoir. This material transport process is stable overlong terms and it protects the surface in a well defined manner.

4.1.4.1. Electronics. Bright self-emitting displays based on organiclight emitting diodes (OLEDs) offer new possibilities to adoptflexible displays on the dashboard. Future generations willintegrate transparent OLEDs as a part of the glazings in order topresent information for driver and passenger in a variable manner.This allows for the implementation of new safety features, forexample for the magnified presentation of traffic signs, which arerecognized by eye-trackers and which are displayed on the glazingby camera systems. Head-up displays and touch-screen interfaceswill allow for the presentation of a small subset of information andthus, the control of the car will be much easier and safer [144].

4.1.4.2. Illumination. Glazings will be used for full size illuminationof the interior. This comfort feature will be achieved in short termby SMD-LEDs mounted in the sun roof, but future generations willimplement full size illumination using transparent OLEDs inte-grated in the glazing.

4.1.4.3. Switchable transmission. Blinds will be replaced by fastswitching optical layers in such a way, that only the illuminatedpart of the glazing will be shaded. Also full size shading of theglazing will be possible in order to minimize the thermal load onparking cars and to protect the driver’s privacy on demand.

4.1.4.4. Photovoltaics. Semi-transparent thin film solar cells will beintegrated as a part of the optical design for sun roof elements. Aircontrol units and security devices will be powered by theseelements without any load for the storage battery.

4.2. Lighting

The front, back and side lights of a car are crucial for all safetyaspects. Besides this, they are also important design elements.

Up to the mid-80s, mineral glass was used for the front lightsexclusively. From design and construction viewpoint, however,it was very attractive to substitute mineral glass by othermaterials allowing for complex shapes, ease of production andlight weight solutions. In respect to these demands, polycarbo-nate headlights entered the market. The ford continental from1984 was the first car where mineral glass was replaced bypolycarbonate [61] and nowadays, the market share of coatedpolycarbonate headlights is almost 100%. The technology for PCheadlight coating is similar to the PC glazing. However, thedemands on optical quality and low defect density of the coatingare not as stringent as those for the automotive glazing. State-of-the-art is silicone based hard coatings for scratch and UVprotection [158]. Plasma [166] and hot-wire CVD processesallow for excellent performance, the costs, however are higherthan for wet chemical deposition in this case.

The reflector of the headlight is coated with sputtered highreflective aluminium and covered by SiO2 for corrosion protection[73].

Inorganic LEDs open up new pathways for headlight design andconstruction. Due to the reduced heating of the headlight anti-fogging layers on the inner side of the transparent housing [153]will be necessary for proper operation. Thin and low energy OLEDswill enable arbitrary shaped automotive lighting [131].

4.3. Information display

AR coatings are applied on the instrumental cluster andaccessories such as navigation systems to minimize unwantedreflections disturbing the driver’s view [156]. Besides this, allaspects of display and touch screen technologies are important forautomotive information display [160]. New developments addressall aspects for OLED technology [139], such as OLEDs with atransparent active driver matrix [70] and flexible OLED displays[1].

5. Process and production technology

5.1. Plasma processes

Thin film deposition and surface treatment processes based onlow pressure plasmas are still the key to realize many innovativesurfaces in automotive engineering. The two basic families arephysical vapour deposition (PVD) and plasma assisted chemicalvapour deposition (PACVD).

Evaporation and sputtering are the most important PVDprocesses. They require vacuum, since single particles have tobe transported over a distance of several tens of cm from thecoating source to the substrate without significant energy loss. Thecoating material is solid, thin films are deposited via the transitionsolid–liquid–vapour–solid in case of evaporation or solid–vapour–solid in case of sputtering.

Evaporation is the oldest PVD process. Materials with anappreciable vapour pressure at temperatures up to 1500 8C (thisholds for many metals) may be evaporated by resistive heating, formaterials with a higher melting point (e.g. metal oxides) electronbeam evaporation is used [9]. Evaporation is a rather fast processwith deposition rates in the range of several mm/s. However, filmquality and adhesion to the substrate may suffer from the lowenergy (around 0.2 eV) of evaporated particles. More sophisticatedevaporation processes therefore make use of an additional plasma(Fig. 23).

The evaporated particles crossing the plasma zone are activatedand ionized and consequently can form a much denser film [124].Plasma activated electron beam evaporation is nowadays thepreferred process for manufacturing of antireflective coatings onlenses for optical instruments or spectacles [197].

Sputtering is often called a ‘‘billiard game with ions and atoms’’.Positive ions (in industrial processes mainly argon is used asprocess gas) are generated in a plasma which is ignited between a

Fig. 23. The principle of plasma assisted electron beam evaporation.

Fig. 24. The sputter process on an atomic scale.

Fig. 25. The principle of magnetron sputtering. Electrons are trapped by the Lorentz

force K ¼ eðy� BÞ in an inhomogeneous magnetic field, resulting in an enhanced

ionisation of argon atoms.

Fig. 26. Industrial coating equipment for sputter deposition of DLC (from graphite

targets) or Me-DLC. Two magnetron cathodes are shown in the left side of the

picture.


cathode (sputter target) and an anode (substrate). They areaccelerated in the electric field, hit the target surface and transfertheir energy to the target atoms which are ejected and form a thinfilm on the substrate (Fig. 24). If a reactive gas (e.g. oxygen ornitrogen) is added to the argon, metal oxides, nitrides or variouscompound films can be deposited. Compared to other depositiontechnologies, sputtering is a rather slow process (deposition ratesin the range of nm/s). However, since the energy of sputteredatoms is around 10 times higher than the energy of evaporatedparticles, dense and smooth thin films with a high quality can beobtained.

With the introduction of the planar magnetron cathode in thelate seventies [30] sputtering began to conquer all industrialbranches needing thin film technologies for the realization of newor improvement of existing products. The main advantages ofmagnetron sputtering are:

� L
Fig. 27. The principle of sputtering with a rotatable magnetron (‘‘C-MAG’’).
ow plasma impedance and thus high discharge current in therange of 1–100 A (depending on target length) at typical voltagearound 500 V;
� D eposition rates ranging from 1 nm/s to 10 nm/s (in some cases
up to 50 nm/s) and thus suitable for economic mass production;
� L ow thermal load on the substrate (made the film deposition on
temperature sensitive substrates possible);
� E xcellent plasma and coating homogeneity even for cathodes
with a length of several meters;
� D ense and well adherent films; � H uge variety of coating materials.
The operation of a magnetron cathode is based on the trappingof electrons in a magnetic field according to Fig. 25. An industrialsputter coater for the deposition of DLC or Me-DLC on tools orcomponents is shown in Fig. 26.

The most severe inherent problems of planar magnetronsputtering were the poor target material utilization of around25% and the process instabilities accompanying the reactivedeposition of insulating materials like SiO2 or Al2O3 in DC powereddischarges. Both problems have been solved through intensiveR + D work during the last two centuries.

In 1985 Wright and Beardow [189] reported on a tubularmagnetron which was industrialized as ‘‘C-MAG’’ [122] severalyears later. According to Fig. 27 the target is a tube rotating arounda fixed magnetic field. With such rotatable magnetrons a materialutilization of 90% and a target lifetime of several weeks may beachieved.

Pulse magnetron sputtering operated by power supplies in afrequency range from 10 kHz to 100 kHz has been introduced forthe long term stable high rate deposition of insulating oxides ornitrides in particular on large areas. Fig. 28 illustrates the principleof a dual magnetron unit. At any time, one of the identical plasmasource acts as sputter cathode, while the other one acts as anode.Process instabilities during deposition of insulating materials arealmost eliminated.

In 1999, Kouznetsov et al. [108] reported on film depositionusing high power pulse magnetron sputtering (HPPMS) at targetpower densities up to 2800 W/cm2 (‘‘conventional’’ DC dischargesare operated at 20–50 W/cm2).

Fig. 28. The principle of pulse magnetron sputtering from a dual magnetron unit.

Fig. 29. High power pulse magnetron sputtering in an industrial hard coating

machine. Due to the high power the light emission is much more intensive than in

the conventional magnetron plasma. (Source: SVS Vacuum Coating Technologies.)

Fig. 30. DLC formation with PACVD (schematic).


At typical pulse duration of 50 ms and frequencies around 50 Hzthe mean power dissipated in such a discharge is similar to the DCcase. In an HPPMS process a high amount of the film formingspecies is ionized (50–90%) which results in dense films. DeKovenet al. [41] report on HPPMS deposited DLC films with a density of2.7 g/cm3 (2.0 g/cm3 are usually obtained with DC sputtering[122]).

HPPMS processes are already established in industrial coaters,an example is shown in Fig. 29.

In CVD processes thin films are formed directly from the gasphase. The source material, a so called precursor, is a vapour. Liquidmaterials may be employed, but they have to be transferred to thevapour phase. There are vacuum based CVD processes and thosetaking place under atmospheric pressure. The energy supplied tothe precursor gas in the CVD reactor is used to break bonds, the filmis formed from the fragments. Depending on the method of energysupply we distinguish between thermal CVD and plasma assistedor PACVD. Thermal CVD requires rather high process temperatures(up to 1000 8C) and therefore is limited to heat resistant substrates,while PACVD is a rather ‘cold’ process and thus suitable even forplastics.

The deposition rates of CVD processes are in the range of severalto several tenth of nm/s. A typical application of PACVD is thedeposition of DLC, this process is schematically shown in Fig. 30.

Suitable precursor gases are acetylene (C2H2) or methane (CH4).At deposition rates of 1–2 mm/h and a required thickness of severalmicrometers the deposition time is in the range of a few hours.

A further important PACVD process is the deposition ofamorphous silicon from silane (SiH4), a silicon containing gas.

Thin film transistors that control the individual pixels in an activematrix liquid crystal display or absorber films in Si-based thin filmsolar cells consist of amorphous silicon. From these examples it isobvious that PACVD is a key manufacturing process for innovativeproducts.

Hot filament activated chemical vapour deposition (HFCVD) is avacuum based thermal CVD process using an array of tungstenwires which are heated to temperatures between 2000 8C and3000 8C [149,119].

The coating of large two-dimensional plates (size up to500 mm � 1000 mm) or substrates with a cylindrical geometryis possible in different reactors, as shown in Fig. 31. HFCVD hasbeen used for the deposition of polycrystalline diamond on largeareas. The feasibility of manufacturing amorphous silicon, micro-crystalline silicon, and silicon nitride has been demonstrated.HWCVD may be an important step on the way to cost effectivesolar cell production.

5.2. Electrochemical processes

Electrochemical processes (electroplating, electroless plating,electrophoretic painting) are the most important surface technol-ogies in the automotive industry. The most important propertiesare an increased corrosion resistance, tribological functions likewear resistance or reduced friction properties and decorativeaspects.

About 40% [90] of the products of the electroplating industry areintended for the automotive industry, primarily for corrosionresistance.

5.2.1. General technical process

The most important deposition metals in a car are zinc, nickeland chromium.

Typical of these metals, the equation for the electro-depositionof nickel is shown in the following equation:

cathode : Ni2þ þ2e� ! Ni (1)

On the other side, metallic nickel will be dissolved according tothe following equation:

anode : Ni ! Ni2þ þ2e� (2)

The process works in a so called Watt’s electrolyte, based on asolution of Nickel sulphate with small amounts of Ni-chlorides. Inorder to keep the pH-value constant at 3–4, boric acid is added. Theaverage current density is about 5 A/dm2. Organic additives caninfluence the grain refinement and levelling of the coating in orderto achieve a dense, bright shining surface [20].

The deposition of the metal can be performed either in a rackplating process for larger parts or in a so called barrel platingprocess, where small parts like screws are placed in a barrel, whichis rotating in the electrolyte bath during the deposition process.

Fig. 31. HFCVD reactors for flat and cylindrical substrate geometries.


5.3. Corrosion protection

5.3.1. Electrodeposition of zinc and zinc alloys

The most important coating metal is zinc in combination withconversion layers and/or cathodic dip painting layers for corrosionprotection (see below). The main reasons for choosing zinc forcorrosion protection are the relatively low price and the ability toprovide cathodic protection to steel, while maintaining a low zinccorrosion rate in non-aggressive environment, due to the forma-tion of passive layers of zinc hydroxide.

Zinc plating is realized by two different electroplatingprocesses. Single parts are coated by a so called batch process,either a rack process or a barrel process; larger parts can beproduced from steel which is coated with zinc in an endless coil-to-coil plating process and then subsequently formed to car doors orengine hoods.

To an increasing extent, the pure zinc layer is being replaced bya zinc–nickel alloy with a nickel content of about 10–15%. Thecorrosion resistance is increased compared to a pure zinc layer,however, the costs are higher [63,26,57,58]. Generally, the zinc (-alloy) layer is only a part of a complex corrosion protection systemconsisting of the metallic layer, the hexavalent chromium freeconversion layer and the painting system.

5.3.2. Hot dip galvanizing

Hot-dip galvanizing (HDG) is the process where steel coils in acontinuous process or metal parts (batch galvanizing) areimmersed in a bath of molten zinc, resulting in a well-adheredzinc–steel alloy coating that protects the steel from corrosion. Thetemperature of the molten zinc is about 460 8C and the thicknesslayer varies from about 8 mm for coil coating processes and 15–20 mm for the coating of single parts.

Both processes, electroplating of zinc and hot dip galvanizing arewell known processes on usual steel, however, the upcoming of newtypes of steel with a high strength like the TRIP steel (transforma-tion-induced plasticity) causes some problems. The addition ofcertain alloying metals like Al or Mn passivates the surface of thissteel and reduces the wettability during the hot dip galvanizingprocess resulting in a lower adhesion [8]. The electroplating of zincon the TRIP-steel reduces the dynamic tensile strength [191].

5.3.3. Conversion layers

The so called directive on ‘‘End-of life vehicles’’ (ELV) [33] bansthe application of certain heavy metals like lead, cadmium,mercury and hexavalent chromium in the automotive industryfrom July 2007. However, hexavalent chromium was one of themost efficient corrosion protective coatings on zinc plated steeland aluminium. This was not only because of the relatively highcoating thickness of about 200–400 nm but also due to the socalled self-healing effect. This effect, not yet really understood,covers a small crack, caused for example by a mechanical damage,again with hexavalent chromium and saves the surface againstcorrosion attack.

Commercially available are technical solutions based ontrivalent chromium (passivation) which is considered to be non-hazardous [39,184,141]. Depending on the coating thickness, suchprocesses are known as thin layer passivation (about 50 nm) andthick layer passivation (about 200–500 nm). Additionally, a Si-based seal coating can further improve the corrosion protection.

5.3.4. Cathodic dip painting: (CDP)

The priming of a car body is carried out nearly completely withthe cathodic dip painting process. In a bowl which is filled with thepriming paint based on an epoxy resin the car body is connected asthe cathode, while a stainless steel sheet is the anode. A voltage ofabout 320–360 V is applied. However, there is no direct electro-deposition but an electrocoagulation: due to the water electrolysis,the pH-value at the cathode increases and causes the discharge ofthe positively charged particles according to:

R3N ðinsolubleÞ þ R-COOH ! R3NHþ ðsolubleÞ þ R-COO�

4 H2O þ 4e� ! 2H2þ4OH�

R3NHþ ðsolubleÞ þ OH� ! R3N þ H2O

ðprecipitation on the car bodyÞ

where R3N is the film former (insoluble amine salt); R-COOH the(solubilising acid); R3NH+ + R-COO� the solubilised positivelycharged polymer.

The dissolved positively charged polymer precipitate on thesurface and form a dense, electrical insulating layer. The coatingthickness of this process is very homogenous.

Cathodic dip painting is possible on steel, zinc-plated steel,aluminium and magnesium. The process is usually combined withinorganic conversion layers like zinc phosphate in order to improvethe adhesion or hexavalent chromium free layer for an additionalcorrosion protection. CDP is an optimal priming process for thecombination with powder- or conventional coating [29]. A schemeof the CDP-process of car bodies is shown in Fig. 32.

5.4. Plastic metallisation and decorative plating

5.4.1. Plastic metallisation

Due to the fact that weight saving in automotive industry is acritical objective, the substitution of metallic parts with plasticparts is still going on. A lot of parts are visible and therefore, theyneed an attractive surface.

The market for the plastic metallisation is about 60 million sp.y. only for the automotive industry [136]. The most commonpolymers are acrylonitrile–butadiene–styrene (ABS) and relatedblends with polycarbonate (PC) and polyamide, which are used formirror frames, door knobs, electrical switches and more (seeFig. 33).

Compared to the metallisation of metal substrates, the adhesionof a metallic layer on polymers is completely different, due to thefact that polymers are electrical insulators. The adhesion is not

Fig. 32. Scheme of the CDP-process with car bodies.

Fig. 33. Chromium-plated door knob of polyamide.


caused by a metal–metal bond but by a mechanical bonding. Thecoating process can be described in following steps:

(1) E
tching with Cr6+ containing sulphuric acid in order to get arough, hydrophilic surface;
(2) T
reatment with catalytic active palladium nuclei; (3) F irst metallisation step with a thin autocatalytic electroless
deposited nickel layer;
(4) R
Fig. 34. SEM-picture of an oil containing nickel composite coating.

einforcement of the thin layer with an electrodepositedcoating of copper and/or nickel.

Usual, the metallisation of plastic parts is intended fordecorative applications, thus the main top coating is a thinchromium layer [38].

5.4.2. Decorative plating

The favourite metal for decorative metallisation is chromium inseveral versions like bright or dull chromium.

The coating thickness is about 0.5 mm; however, the kind ofchromium coating depends from the nickel interlayer which isabout 10–20 mm thick. For a bright chromium layer, the nickellayer needs a strong levelling effect which can be achieved by theaddition of organic additives (leveller, grain refiner). For a dullchromium layer some oil drops will be added to the nickelelectrolyte which will be adsorbed and cause a velvety surface.However, the resulting chromium layer will not influence thesurface, but only the colour.

Although metallic chromium is not considered to be hazardous,it will be deposited from a hexavalent electrolyte which is acutelytoxic and can cause cancer. Thus, more and more electrolytesuppliers and job-coaters try to substitute the Cr(VI)-electrolytewith a non-toxic trivalent electrolyte. In former times, Cr fromtrivalent baths suffers from a brownish colour, but recentsuccesses show that it is possible to deposit the same bluish tintas occurs with hexavalent chromium baths [114,177,48].

5.5. Wear resistance

A lot of wear resistant parts are used in cars, e.g. cam shafts,valves, shock absorber, piston rods and rings, bearings and others.Most of them are coated with a hard chromium layer which is avery popular layer with a high hardness of about 1100 HV and agood corrosion resistance. The layer thickness varies from about10 mm to more than 100 mm [114]. However; the coating is very

inhomogeneous and thus, the coating thickness is much higherthan the target value. The correct value is subsequently obtainedby grinding and polishing processes.

A very special layer is a chromium composite coating withembedded hard particles like diamond or alumina. Normally,chromium based composites are not possible due to the stronghydrogen evolution, however it succeeds with a special pulse-plating process [23,24].

For some special applications in racing cars and motor-bikes acomposite coating based on electroless nickel–phosphorus alloywith embedded particles of SiC are used.

5.6. Outlook and latest developments

Although the electroplating industry is well established, newdevelopments are necessary to meet the demands of automotiveindustry. These are in particular weight saving, improved corrosionprotection and legal requirements.

Magnesium is a light metal which is more and more interesting,but it suffers from corrosion susceptibility. Up to now, there areonly few magnesium parts mounted in a car. New processes forelectrodeposition on magnesium as well as new chromium freeconversion layers offer an opportunity to develop new corrosionresistant magnesium systems [45,176].

In order to improve the corrosion protection of steel with zinccoatings, the steel industry has developed a new coating system,based on electroplated (ZEMg) or hot dip plated zinc (ZMg) with anadditional thin layer of PVD-deposited magnesium. The Mg-layershifts the electrochemical potential to more negative values andreduces the corrosion on steel [154,155,157]. This system shouldbe applied for coil coating processes.

Legal requirements ban the use of hexavalent chromium as aconversion layer and trivalent chromium is for most applications atechnical adequate solution. However, there is concern about thegeneral use of chromium, and thus, new passivations withcompletely chromium-free conversion layers, based on variousmaterials like cerium, vanadium, molybdenum or molybdate–zinchave been developed. The corrosion protection will be furtherincreased in combination with paintings [188,159].

The process of composite plating requires insoluble andchemical inert particles in the electrolyte. With the so calledmicroencapsulation it is possible to transfer liquid or chemicalactive substances into a solid phase which is inert in theelectrolyte. With this technique it is possible to embed forexample microencapsulated oil (see Fig. 34) or molybdenumsulphide in metallic coatings for low friction applications or

Fig. 35. Phase differences depending on the normalized layer thickness x for

different values of the thermal reflection coefficient R.


corrosion inhibitors for an improved corrosion protection (self-healing effect) [44].

6. Coating characterization

The development of new coating technologies requires novelmeasuring techniques, particularly non-destructive inspectionmethods, in order to ensure the desired coating properties likelayer thickness, hardness, homogeneity and others. In most cases,they are restricted to certain materials or are applicable onlywithin a limited range of coating parameters. Some measuringmethods have been successfully transferred into industrialenvironments. The most important methods to analyse coatingproperties are discussed in the following sections.

6.1. Photothermal measuring techniques

Photothermal techniques form a class of different measuringmethods. Their common feature is the generation of thermal waveswithin a specimen. This is usually realized by exposing the surfaceto intensity modulated laser radiation. The partial absorption ofthis radiation means a periodical energy deposition. Mathemati-cally, such a situation is described by the thermal diffusionequation [69], which is given for a one-dimensional heatpropagation by

@@z

kðzÞ @@z

Tðz; tÞ� �

� rðzÞcðzÞ @T

@tðz; tÞ ¼ �Hðz; tÞ (3)

The source term H(z,t) expresses the density of heat sourcesalong the z-axis and its time dependence.

In order to analyse coating properties, those solutions of thethermal diffusion equation are important which represent stronglydamped temperature waves [69]:

Tðz; tÞ ¼ T0 e�ðz=mÞ cos vt � z

m� p

4

� �(4)

T0 is the temperature amplitude at the coating surface. ForEq. (4) it is assumed that all radiation energy is absorbed directly atthe surface and that the heat propagates only one-dimensionally inz-direction. This condition is often fulfilled, at least approximately.

The quantity m is called the ‘‘thermal diffusion length’’, which iscoupled to the thermal wavelength lth:

lth ¼ 2pm (5)

Eq. (5) together with (4) show that a thermal wave is dampedout nearly completely within a propagation distance of onethermal wavelength.

If a thermal wave encounters an interface to a substrate withdifferent thermal properties, a fraction of it is reflected andpropagates back to its origin, where it will interfere with the initialthermal wave. The thermal reflection coefficient R of the interfacehas the form [12]

R ¼ 1� ðeS=eLÞ1þ ðeS=eLÞ

(6)

where eS, eL are the thermal effusivities of the substrate (S) and thelayer (L), which depend on the thermal conductivity k, the densityr and the heat capacity c of the corresponding material:

e ¼ffiffiffiffiffiffiffiffikrc

p(7)

Commonly, multiple reflections between the layer surface andits interface to the substrate occur, resulting in a surfacetemperature oscillation T(t) which shows modified amplitudesand phase differences with respect to the excitation radiation. Incontrast to the amplitude of the thermal wave, its phase differenceis not influenced by the absorption of the excitation energy. Thedependence of the photothermal phase on the coating thickness d

(here normalized to the thermal diffusivity m) is shown in Fig. 35for different values of the thermal reflection coefficient R. For the

phase curve of R = �0.9, a straight line indicates an almost linearrelationship of the phase for a certain range of layer thickness. Thisrange is often used for the photothermal thickness analysis ofcoatings.

The surface temperature T(t), from which amplitude and phasesignals can be analysed using lock-in techniques, is most oftenmeasured by infrared sensors [93]. Special techniques had beendeveloped to reduce the time required for surface scans [25,190].

Alternative detection methods like thermo reflection and themirage technique [111,112] are preferred for instance, if theinfrared emissivity is low.

The measurement of layer thicknesses and the detection ofdefects are the most important applications of the photothermalanalysis [12,34]. They are used, e.g. within industrial productionlines to measure the thickness of powder coatings. Not only singlecoatings, but also multilayer coatings can be analysed by multiplefrequency measurements [95,185].

Another application is the determination of thermal para-meters, which requires the knowledge of the coating thickness andthe thermal parameters of the substrate [15,140,68,138].

Due to the fact that delaminations have a strong impact on thethermal contrast of coating interfaces, such defects have asignificant influence on the photothermal signals.

No simple rule can be elaborated to decide whether or not acertain coating parameter can be measured using thermal waves.However, some conditions will be advantageous: a thermalreflection coefficient close to +1 or�1 promises a strong measuringcontrast. Surface absorption and emission allow applying asimplified photothermal model [145]. The analysis of semi-transparent coatings is considerably more complicated [49].

The thermal diffusion length m should be in the same order asthe layer thickness. This can often be achieved, because m is afunction of the modulation frequency. The coating thicknesseswhich can be analysed approximately range from 1 mm to 400 mmfor organic coatings and from 10 mm to 10 mm for metalliccoatings.

6.2. Acoustic microscopy

Another non-destructive method to analyse coatings and othernear surface zone structures is acoustic microscopy. This is basedon the generation of high frequency sound waves with piezo-electric transducers, which are focussed by an acoustic lens intothe examined specimen. Structures within the specimen reflect aportion of the sound energy. A part of the reflected acoustic wave isthen collected by the lens and converted into an electric signal bythe same transducer. If the lens is scanned in rows and columnsover the specimen, the signals for all measured points form anacoustic image, where structures indicate the presence of possibledefects [100].


The acoustic reflection coefficient Ra of an interface can bedefined as [2]

Ra ¼Z2 � Z1

Z2 þ Z1(8)

where the acoustic impedance Z is the product of the density r andsound velocity ys : Z ¼ rys.

The acoustic wave is reflected at the lens surface if no couplingmedium like water is used, because the acoustic impedance of thelens material, which is commonly sapphire, is considerablydifferent from the acoustic impedance of air. For propagationtime measurements, the transducer cannot emit and receiveacoustic waves simultaneously. Hence, only short pulses ofultrasound waves are emitted and the transducer is then switchedinto the detection mode. The next ultrasound pulse is emitted if nomore echoes are expected.

The signal amplitude yields information about the acousticimpedance of the structure which caused the echo. If the soundvelocity is known, the time from the emission of the pulse to thedetection of its reflection allows calculating the distance from thelens to the structure.

If microscopic defects like blisters within a coating ordelaminations of the interface have to be analysed [193,47], theresolution of the acoustic microscope becomes an importantparameter. It can be shown that the lateral resolution increaseswith the lens aperture and with the frequency of the acoustic wave.Unfortunately, the absorption of the acoustic waves increases withthe square of the frequency. This circumstance limits the detectiondepth.

In practise, one has to find a compromise between penetrationdepth and lateral resolution.

6.3. Micromagnetics

Magnetic measuring principles are based upon the correlationbetween the surface zone parameters of a workpiece and thecorresponding change of the electromagnetic material properties.Thus, these methods are restricted to materials with reasonableelectrical conductivity (e.g. eddy current measuring methods) andferromagnetic properties (magnetic and micromagnetic methods)[4]. Nevertheless, all ferromagnetic and antiferromagnetic materi-als show a strong interaction between the magnetic dipoles andWeiss domains. Since they cover a large spectrum of technicallyvery important workpieces, micromagnetics have gained asubstantial progress during the last 20 years, due to intensiveresearch work [69].

Some of the most important magnetic measuring methods arethe eddy current method, the Barkhausen effect, the superpositionpermeability and the harmonic analysis, all non-destructivetesting methods [162].

The eddy current principle is based on the impedance analysisof a sample. Depending on interactions between the magnetic fieldgenerated by a coil and an object, conductivity and permeabilityrelated changes in the impedance occur.

For the Barkhausen effect, a stationary electromagnet applies analternating magnetic field to a ferromagnetic sample. Thealternating magnetization of the sample is stimulated by changingmagnetic domain sizes through jumps of the domain-separatingBloch walls [163].

The micromagnetic testing methods enable the microstructurecharacterization, detection of micro-failures and evaluation of thelocal distribution of residual stresses, adhesion strength, mechan-ical hardness and coating thickness [171,4,170,65].

6.4. X-ray diffraction

X-ray scattering techniques are non-destructive methods forthe analysis of the crystallographic structure, chemical composi-tion and physical properties of materials and thin films. Thesetechniques are based on the measurement of the scattered

intensity, caused by an X-ray beam irradiating a sample, as afunction of incident and scattered angle, polarization andwavelength or energy.

Thin film diffraction and grazing incidence X-ray diffraction areused for the characterization of crystallographic structures andpreferred orientation of substrate-anchored thin films. High-resolution X-ray diffraction enables the characterization ofthickness, crystallographic structure and stress in thin epitaxialfilms [168,32,195].

In the case of coatings and films, the substrate and thedeposition process may result in very high residual stress fieldswhich can affect both performance and surface integrity, sinceadhesion or cracking resistance can be strongly altered [64]. In thecase of very thin coatings, the film contribution to the diffractionpattern can be hidden by that of the substrate. In these cases, aglancing incidence X-ray diffraction (GIXRD) technique is pre-ferred, since the penetration depth can be strongly reduced bychoosing incident angles close to the critical angle [196]. In thisgeometry the diffracting planes are generally not parallel to thesample surface and it is possible to study the structure of thecoatings as a function of the X-ray penetration depth [64].

6.5. Surface metrology

The surface geometry of functional coatings can be character-ized in different ways. The prevalent methods work either in atactile or non-contact mode. A classical tactile measuring system isthe profilometer – traditionally called stylus instrument – and itworks like a phonograph. For the atomic force microscope [31],however, the ‘‘contact’’ to the surface is caused by atomicinteractions.

Non-contact methods can be divided into vertical and lateralscanning procedures. In most cases, they are based on opticalmeasuring principles. But also acoustic measuring methods can beapplied [67]. Some examples for vertical scanning devices are thewhite light interferometer and the confocal microscope [110]. Twocases for lateral scanning systems are fringe projection and laserscanning. With the procedures specified above it is possible toassess the surface geometry via standardized roughness andwaviness parameters.

Apart from these standardized characterizations of surfacegeometry, laser optical light scattering methods like the angleresolved scattering (ARS) and other speckle techniques are veryconvenient, since the objective areal roughness parameters areintegrally determined.

7. Summary and visions

The most important aspects of surface technologies forautomotive engineering have been discussed in this paper.Tribological coatings on tools nowadays are the key for efficientmanufacturing processes. Several families of such coatings havebeen developed during the past 30 years, ranging from differentmetal nitrides like TiN, TiAlN or CrN to various carbon based films.Superhard c-BN is on the way to industrialization, bridging the gapbetween nitrides and diamond and with a temperature stabilitysuperior to that of diamond. Due to their high hardness and lowcoefficient of friction, diamond-like carbon films are of greatinterest for various drive components. Introduced on highperformance injection nozzles around 15 years ago, today theirapplication in automotive technology is still limited, but willsubstantially grow in the future, being pushed by the need forreduction of fuel consumption and the desire for longer lifetime ofcomponents. The ultimate dream is the engine that runs withoutany lubricants.

Even today the car driver has to suffer from all the disadvanta-geous optical and thermal properties of glass. Together with asubstantial increase of glazed area there is an increasing demand toeliminate these disadvantages and add more functionality to theglass by suitable coatings. The basic desire of the driver is certainly


more comfort through a simple de-icing procedure in winter as wellas a substantially reduced heat transfer during hot summer days.Further visions are self-cleaning instead of ‘‘easy-to-clean’’ glasssurfaces and the integration of sensors or semi-transparent displaysinto the windscreen. Many coatings which can fulfil above-mentioned desires already do exist. Highly selective sun controlfilms with a transmission of more than 90% in the visible and a highreflection in the near infrared part of the solar spectrum can easily berealized, but their manufacturing costs are still prohibitive for use inautomobiles.

Electrochromic coatings with variable transmission willreplace mechanical blinds in sunroofs in the future and theywill also be used on side and rear windows for privacy reasons.

For 20 years there have also been strong efforts to replacemineral glass by polycarbonate (PC), where weight reductionand increased safety are the main reasons. Highly scratchresistant surface coatings are necessary to protect the soft PC,and an additional UV blocker has to be integrated in orderto avoid its degradation. To realize such complex films inan industrial scale and at reasonable costs is an ongoingchallenge.

Improved corrosion protection of steel strips used for the carbody is a further object of current research and developmentactivities. Zinc magnesium alloys or SiOx deposited by plasmaactivated evaporation will most probably replace conventionalcorrosion protection in the near future. The combination of thehigh hardness and wear resistance of DLC films and its piezo-electric properties are the basis for realization of novel tempera-ture and force sensors, which can be used even in harshenvironments and thus add more comfort and safety to the car.Finally, automotive industry and drivers dream of surfaces thatrepair themselves, even after mechanical degradation. Electro-plated composite films containing capsules with corrosioninhibitors is one of the approaches on the way to such intelligentsurfaces.

In conclusion, surface manufacturing technologies are one ofthe keys to add more safety and comfort to future cars.

References

[1] Akedo K, Miura A, Fujikawa H, Taga Y (2006) Flexible OLEDs for Automobilesusing SiNx/CNx:H Multi-layer Barrier Films and Epoxy Substrates. Journal ofPhotopolymer Science and Technology 19:203–208.

[2] Alig I, Tadjbach S, Krueger P, Oehler H, Lellinger D (2009) Characterisation ofCoating Systems by Scanning Acoustic Microscopy: Debonding. Blistering andSurface Topology Progress in Organic Coatings 64(2/3):112–119.

[3] Almeida FA, Sacramento J, Oliveira FJ, Silva RF (2008) Micro- and Nanocrystal-line CVD Diamond Coated Tools in the Turning of EDM Graphite. Surface andCoatings Technology 203:271–276.

[4] Altpeter I, Hoffmann J, Kopp M, Grimm H, Nichtl-Pecher W (2000) Character-isation of Thin Ferromagnets Using Barkhausen Noise Microscopy. PraktischeMetallographie-Practical Metallography 37(5):261–270.

[5] Bach FW, Mohwald K, Laarmann A, Wenz T (2005) Moderne Beschich-tungsverfahren. Wiley-VCH Verlag.

[6] Barbezat G (2006) Thermal Spray Coatings for Tribological Applications in theAutomotive Industry. Advanced Engineering Materials 8:678–681.

[7] Bech J, Bay N, Eriksen M (1999) Entrapment and Escape of Liquid Lubricant inMetal Forming. Wear 232:134–139.

[8] Bellhouse EM, Mertens AIM, McDermid JR (2007) Materials Science andEngineering A 463:47–156.

[9] Belkind A (2007) Electron Beam Evaporation. Society of Vacuum Coaters, 50Years of Vacuum Coating Technology. 105–107.

[10] Bello I, Chan CY, Zhang WJ, Chong YM, Leung KM, Lee ST, Lifshitz Y (2005)Deposition of Thick Cubic Boron Nitride Films: The Route to Practical Appli-cations. Diamond and Related Materials 14:1154–1162.

[11] Benda BC (2007) Finishing Options for Polycarbonate Automotive Glazing.Proceedings Glass Performance Days, 763–765.

[12] Bennett CA, Patty RR (1982) Thermal Wave Interferrometry: A PotentialApplication of the Photoacoustic Effect. Applied Optics 21(1):49–54.

[13] Bewilogua K, Wittorf R, Thomsen H, Weber M (2004) DLC Based CoatingsPrepared by Reactive d.c. Magnetron Sputtering. Thin Solid Films 447–448:142–147.

[14] Bewilogua K, Cooper CV, Specht C, Schroder J, Wittorf R, Grischke M R (2000)Effect of Target Material on Deposition and Properties of Metal-containingDLC (Me-DLC) Coatings. Surface and Coatings Technology 127:224–232.

[15] Beyfuss M, Reichl H, Baumann J (1992) Thermal Characterization of Thin Layers,Photoacoustic and Photothermal Phenomena III. Springer Verlag, Berlin. 692–694.

[16] Biehl S, Luthje H, Bandorf R, Sick JH (2006) Multifunctional Thin Film SensorsBased on Amorphous Diamond-like Carbon for Use in Tribological Applica-tions. Thin Solid Films 515:1171–1175.

[17] Bobzin K, Ernst F, Richardt K, Schlaefer T, Verpoort C, Flores G (2008) ThermalSpraying of Cylinder Bores with the Plasma Transferred Wire Arc Process.Surface and Coatings Technology 202:4438–4443.

[18] Bouzakis E (2008) Steigerung der Leistungsfahigkeit PVD-beschichteter Hart-metallwerkzeuge durch Strahlbehandlung. Diss. RWTH Aachen.

[19] Brewe DE, (2001) Slider Bearings—Slider Bearing Materials.Bhushan B, (Ed.)Modern Tribology Handbook, vol. 2. CRC Press, Boca Raton. p. 1027.

[20] Brugger R (1984) Die galvanische Vernickelung, 2 Auflage Leuze VerlagSaulgau.

[21] Bruzzone AAG, Costa HL, Lonardo PM, Lucca DA (2008) Advances in Engi-neered Surfaces for Functional Performance. CIRP Annals-Manufacturing Tech-nology 57:750–769.

[22] Bunshah RF (1994) Handbook of Deposition Technologies for Films and Coatings.2nd ed. Noyes Publications, Park Ridge.

[23] Buran U, Linde R, Neuhauser H-J (1990) Galvanic Hard Chromium Layer.European Patent EP217126 B1, July 4, 1990 (submitted August 26, 1986).

[24] Buran U, Linde B, Neuhaeuser H-J (1989) Galvanische Hartchromschicht.German Patent DE3531410 C2, March 23, 1989 (submitted September 3,1985).

[25] Busse G, Wu D, Karpen W (1992) Thermal Wave Imaging with Phase SensitiveModulated Thermography. Journal of Applied Physics 71(8):3962–3965.

[26] Byk TV, Gaevskaya TV, Tsybulskaya LS. (2008) Surface and Coatings Technol-ogy 202:5817–5823.

[27] Cabral G, Gabler J, Lindner J, Gracio J, Polini R (2008) A Study of Diamond FilmDeposition on WC–Co Inserts for Graphite Machining: Effectiveness of SiCInterlayers Prepared by HFCVD. Diamond and Related Materials 17(6):1008–1014.

[28] Cabral G, Reis P, Polini R, Titus E, Ali N, Davim JP, Gracio J (2006) CuttingPerformance of Time-modulated Chemical Vapour Deposited DiamondCoated Tool Inserts during Machining Graphite. Diamond and Related Materi-als 15:1753–1758.

[29] CDP. (1995) in Frettis G, (Ed.) Automotive Paints and Coatings. VCH Verlags-gesellschaft, Weinheim.

[30] Chapin JS (1979) Sputtering Process and Apparatus. U.S. Patent 4,166,018,August 28, 1979 (submitted January 31, 1974).

[31] Chung K, Kim D (2007) Wear Characteristics of Diamond-coated Atomic ForceMicroscope Probe. Ultramicroscopy 108(1):1–10.

[32] Colombi P, Zanola P, Bontempi E, Roberti R, Gelfi M, Depero LE (2006)Glancing-incidence X-ray Diffraction for Depth Profiling of PolycrystallineLayers. Journal of Applied Crystallography 39:176–179.

[33] Conversion Cr-free: Directive 2000/53/EC of the European Parliament (2000)End of life vehicle (ELV).

[34] Crostack H-A, Jahnel W, Meyer EH, Selvadurai-Lassl U (1996) Developmentsin Non-destructive Testing of Surface Coatings. Welding in the World (UK)37(3):114–120.

[35] Cselle T (2005) Application of Coatings for Tooling Quo Vadis 2005. Vakuum inForschung und Praxis VIP 17(S1):33–39.

[36] Cselle T (2004) Coating for Tooling 2004—Questions and their Answers. SwissQuality Production 1.

[37] Cselle T, Holubar CH, Malin N (2003) Driving Forces of Today’s ManufacturingTechnology. Proceedings 3rd Conference for Milling, 33–60.

[38] Dahlhaus M (2001) JOT Journal fur Oberflachentechnik 41(9). 60, 62–65.[39] Dahlhaus M (2005) JOT Journal fur Oberflachentechnik 45(4):72–73.[40] De Barros Bouchet MI, Martin JM (2008) in Donnet C, Erdemir A, (Eds.) New

Trends in Boundary Lubrication of DLC Coatings. Tribology of Diamond-likeCarbon Films. Springer Science + Business Media, LLC, New York, p. 591.

[41] DeKoven BM, Ward PR, Weiss RE, Christie DJ, Scholl RA, Sproul WD, TomaselF, Anders A (2003) Carbon Thin Film Deposition Using High Power PulsedMagnetron Sputtering. 46th Annual Technical Conference Proceedings, Societyof Vacuum Coaters, pp. 158–165.

[42] Denkana B, Becker JC, Spengler C, Karyazin A (2004) Influence of DifferentManufacturing Steps on Characteristics of Coated Carbide. The Coatings,Conference Proceedings, 69–76.

[43] Derflinger V, Brandle H, Zimmermann H (1999) New Hard/Lubricant Coatingfor Dry Machining. Surface and Coatings Technology 113:286–292.

[44] Dietz A, Jobmann M, Rafler G (2000) Matwiss u Werkstofftech 31:612.[45] Dietz A, Klumpp G (2007) Magnesium. in Kainer KU, (Ed.) Proceedings of the

7th International Conference on Magnesium Alloys and their ApplicationsWiley-VCH, Weinheim.

[46] Dimigen H, Hubsch H (1983) Applying Low-friction Wear-resistant ThinSolid Films by Physical Vapour Deposition. Philips Technical Review 41:186–197.

[47] Doherty M, Sykes JM (2008) A Quantitative Study of Blister Growth onLacquered Food Cans by Scanning Acoustic Microscopy. Corrosion Science50:2755–2772.

[48] Dyllus T (2006) Galvanotechnik 97(9):2141–2147.[49] Egee M, Dartois R, Marx J, Bissieux C (1986) Analysis of Semitransparent

Layered Materials by Modulated Photothermal Radiometry: Application tothe Bonding and Thickness Control of Enamel Coatings. Canadian Journal ofPhysics 64(9):1297–1302.

[50] Erkens G (2005) A Survey of Advanced Coatings as Key Element of ModernCutting Tools and Functional Components. The Coatings, Conference Proceed-ings, 53–65.

[51] Erkens G, Cremer R, Hamoudi T, Bouzakis KD, Mirisidis I, Hadjiyiannis S,Skordaris G, Asimakopoulos A, Kombogiannis S, Anastopoulos J, Efstathiou K(2004) Properties and Performance of High Aluminium Containing (Ti,Al)NBased Supernitride Coatings in Innovative Cutting Applications. Surface andCoatings Technology 177–178:727–734.


[52] Ernst P, Barbezat G (2008) Thermal Spray Applications in Powertrain Con-tribute to the Saving of Energy and Material Resources. Surface and CoatingsTechnology 202:4428–4431.

[53] Farrington RB (2002) Advanced Automotive Glazings: A Cool Idea for HotCars. 45th Annual Technical Conference Proceedings, Society of Vacuum Coat-ers, pp. 209–215.

[54] Feng X, Jiang L (2006) Design and Creation of Superwetting/AntiwettingSurfaces. Advanced Materials 18:3063–3078.

[55] Finley JJ (1999) Heat Treatment and Bending of Low-E Glass. Thin Solid Films351:264–273.

[56] Finley JJ (2001) The Evolution of Solar Infrared Reflective Glazing in Auto-mobiles. 44th Annual Technical Conference Proceedings, Society of VacuumCoaters, pp. 193–203.

[57] Fontenay F (2002) Galvanotechnik 93(10):2534–2541.[58] Fontenay F (2002) Galvanotechnik 93(11):2827–2836.[59] Forsich C, Heim D, Mueller T (2008) Influence of the Deposition Temperature

on Mechanical and Tribological Properties of a-C:H:Si Coatings on Nitridedand Postoxidized Steel Deposited by DC-PACVD. Surface and Coatings Tech-nology 203:521–525.

[60] Gabler J, Bewilogua K, Biehl S, Brand J, Hofer M, Keunecke M, Schafer L,Thomsen H, Weber M (2007) Tool Coatings—New Developments for Forming,Cutting and Abrasive Machining. Society of Vacuum Coaters (SVC): Society ofVacuum Coaters, Technical Conference Proceedings 1991–2007, Society ofVacuum Coaters, Albuquerque, pp. 608–615.

[61] in GAKKraftfahrzeugscheiben—Glas oder Kunststoff?, vol. 40. GAK. 34–66.[62] Garzino-Demo GA, Lama FL (1996) Front Surface Wear and Corrosion Resistant

Metallic and/or Dielectric Mirrors for Automotive Applications. 39th AnnualTechnical Conference Proceedings, Society of Vacuum Coaters, pp. 270–275.

[63] Gavrila M, Millet JP, Mazille H, Marchandise D, Cuntz JM (2000) Surface andCoatings Technology 123:164–172.

[64] Gelfi M, Bontempi E, Roberti R, Armelao L, Depero LE (2004) Residual StressAnalysis of Thin Films and Coatings through XRD2 Experiments. Thin SolidFilms 450(1):143–147.

[65] Gillies MF, Chapman JN, Kools JCS (1995) Micromagnetic Characteristics ofSingle-layer Permalloy-films in the Nanometer Range. Journal of Magnetismand Magnetic Materials 140:721–722.

[66] Giron JC, Schutt J, Pender D, Beteille F, Fanton X (2003) ElectrochromicAutomotive Sunroofs. Proceedings Glass Processing Days, 460–461.

[67] Goch G, Volk R (1994) Contactless Surface Measurement with a New AcousticSensor. Annals of the CIRP 43:487–490.

[68] Goch G, Prekel H, Patzelt S, Strobel G, Lucca DA, Stock HR, Mehner A (2004)Non-destructive and Non-contact Determination of Layer Thickness andThermal Properties of PVD and Sol–Gel Layers by Photothermal Methods.Annals of the CIRP 53:471–474.

[69] Goch G, Schmitz B, Geerkens J, Karpuschewski B, Reigl M, Sprongl P, Ritter R(1999) Review of Non-destructive Measuring Methods for the Assessment ofSurface Integrity: A Survey of New Measuring Methods for Coatings, LayeredStructures and Processed Surfaces. Precision Engineering 23:9–33.

[70] Gorrn P, Ghaffari F, Riedl T, Kowalsky W (in press) Zinc Tin Oxide Based Driverfor Highly Transparent Active Matrix OLED Displays. Solid State Electronics.

[71] Greenall MR (2003) Heated Glazing for Vehicles. Proceedings Glass ProcessingDays, 519–524.

[72] Grischke M, Hieke A, Morgenweck F, Dimigen H (1998) Variation of theWettability of DLC-coatings by Network Modification Using Silicon andOxygen. Diamond and Related Materials 7:454–458.

[73] Grunwald H, Adam R, Bartella J, Jung M, Dicken W, Kunkel S, Nauenburg KD,Gebele T, Mitzlaff S, Ickes G, Patz U, Snyder J (1999) Better Aluminium Mirrorsby Integra-ting Plasma Pretreatment, Sputtering, and Plasma Polymerizationfor Large-scale Car Headlight Production. Surface and Coatings Technology111:287–296.

[74] Gunji F (2001) Present Status and Future Trend of Coatings on Glass forAutomobiles. Proceedings Glass Processing Days, 502–504.

[75] Hamberg I, Svensson JSEM, Eriksson TS, Granqvist CG, Arrenius P, Norin F(1987) Radiative Cooling and Frost Formation on Surfaces with DifferentThermal Emittance: Theoretical Analysis and Practical Experience. AppliedOptics 26:2131–2136.

[76] Hans M, Buchel R, Grischke M, Hobi R, Zach M (2000) High-volume PVDCoating of Precision Components of Large Volumes at Low Process Costs.Surface and Coatings Technology 123:288–293.

[77] Harbison WC (1993) Protective Coatings for Automotive Transparent PlasticGlazing. SAE Technical Paper Series: 930743-1-8, .

[78] Hata S, Kai Y, Yamanaka I, Oosaki H, Hirota K, Yamazaki S (2000) Develop-ment of Hydrophilic Outside Mirror Coated with Titania Photocatalyst. JSAEReview 21:97–102.

[79] Hieke A, van der Kolk GJ, Tobler M, Bonetti R (2005) Comparison betweenWCC/DLC, CrN/DLC and RF Produced DLC Coatings. 48th Annual TechnicalConference Proceedings, Society of Vacuum Coaters, p. 556.

[80] Hieke A, Bewilogua K, Taube K, Bialuch I, Weigel K (2000) Efficient DepositionTechnique for Diamond-like Carbon Coatings. 43rd Annual Technical Confer-ence Proceedings, Society of Vacuum Coaters, p. 301.

[81] Hieke A (2001) Wear Resistant Modified Diamond Like Carbon Coatings withNon-sticking Properties. Vakuum in Forschung und Praxis 13(1):9–13.

[82] Hill R, Nadel S (1999) Coated Glass Applications and Markets. BOC CoatingTechnology .

[83] Hintze W, Clausen R, Hartmann D, Kindler J, Santos S, Schwerdt M, Stover E(2007) Precision of Machined CFRP—The Challenge of Dimensional Accuracy.1st International Workshop on Aircraft System Technologies, Hamburg, Ger-many, Shaker, Aachen, Germany, pp. 361–374.

[84] Hofmann J, Feichtmaier G, Tropschuh PF (1995) Dammglas—ein Beitrag zurSteigerung des Fahrzeugkomforts. in Abersfelder G, (Ed.) Fahrzeugverglasung.Expert Verlag.

[85] Hogmark S, Jacobson S, Larsson M, Wiklund U, (2001) Mechanical andTribological Requirements and Evaluation of Coating Composites.BhushanB, (Ed.) Modern Tribology Handbook, vol. 2. CRC Press, Boca Raton. p. 948.

[86] Holland-Letz K (2005) Aktuelle Entwicklungen bei Schichtsystemen fur dieTrockenbearbeitung. Vakuum in Forschung und Praxis VIP 17(2):80–85.

[87] Holmberg K, Matthews A. (1994) in Dowson D, (Ed.) Coatings TribologyTribology Series, vol. 28. Elsevier, Amsterdam. p. 371.

[88] Horstmann F, Sittinger V, Szyszka B (2009) Heat Treatable Indium Tin OxideFilms Deposited with High Power Pulse Magnetron Sputtering. Thin SolidFilms 517:3178–3182.

[89] Hu J, Chou YK, Thompson RG, Street S (2007) Characterizations of Nano-crystalline Diamond Coating Cutting Tools. Surface and Coatings Technology202:1113–1117.

[90] IKB Information Deutsche Industriebank (2005) Oberflachentechnik, Berichtzur Branche (Mai).

[91] Jiang W, More AS, Brown WD, Malshe AP (2006) A cBN–TiN CompositeCoating for Carbide Inserts: Coating Characterization and Its Applicationsfor Finish Hard Turning. Surface and Coatings Technology 201:2443–2449.

[92] Jiang W, Malshe AP, Calvin Goforth R (2005) cBN Based NanocompositeCoatings on Cutting Inserts with Chip Breakers for Hard Turning Applications.Surface and Coatings Technology 200:1849–1854.

[93] Kanstad SO (1985) Experimental Aspects of Photothermal Radiometry. Cana-dian Journal of Physics 64(9):1155–1164.

[95] Karpen W, Bohnacker A, Busse G (1991) Dickenmessung an Zwei-Schicht-Lacksystemen auf Kunststoff, Tagungsbericht. Tagung Werkstoffprufung1991, Bad Nauheim, 5.-6. Dezember: 235–242.

[96] Karpuschewski B, Momper F, Cselle T (2008) Coating Development for GearHobs. Confidential Scientific Report.

[97] Karpuschewski B, Byelyayev O, Maiboroda VS (2009) Magneto-AbrasiveMachining for the Mechanical Preparation of High-Speed Steel Twist Drills.Annals of the CIRP 58(1):295–298.

[98] Katsamberis D, Browall K, Iacovangelo C, Neumann M, Morgner H (1998)Highly Durable Coatings for Automotive Polycarbaonate Glazing. Progress inOrganic Coatings 34:130–134.

[99] Keunecke M, Wiemann E, Weigel K, Park ST, Bewilogua K (2006) Thick c-BNCoatings—Preparation, Properties and Application Tests. Thin Solid Films515:967–972.

[100] Khuri-Yakub BT (1993) Scanning Acoustic Microscopy. Ultrasonics 31(5):361–372.

[101] Kim TY, Bialuch I, Bewilogua K, Oh KH, Lee KR (2007) Wetting Behaviours ofa-C:H:SiO Film Coated Nano-Scale Dual Rough Surface. Chemical PhysicsLetters 436:199–203.

[102] Klages CP, Memming R (1989) Micro-structure and Physical Properties ofMetal-Containing Hydrogenated Carbon Films. Materials Science Forum 52–53:609–644.

[103] Klocke F, Krieg T (2001) Coated Tools for Metal Cutting—Features andApplications. The Coatings Conference Proceedings, . P1-1–P1-17.

[104] Klose P (2001) Komfortsteigerung im Automobilbau durch Einsatz von IR-reflektierenden Warmedammverglasungen. in Steinmetz E, (Ed.) Glas imAutomobil. Expert Verlag.

[105] Konig W, Klocke F, Konig M (1995) Hochleistungszerspanung von Graphit.wt-Produktion und Management 85(10):503–509.

[106] Konig W, Fritsch R, Kammermeier D (1992) New Approaches to Characteris-ing the Performance of Coated Cutting Tools. Annals of the CIRP 41(1):49–54.

[107] Koszela W, Pawlus P, Galda L (2007) The Effect of Oil Pockets Size andDistribution on Wear in Lubricated Sliding. Wear 263:1585–1592.

[108] Kouznetsov V, Macak K, Schneider JM, Helmerson U, Petrov I (1999) A NovelPulsed Magnetron Sputter Technique Utilizing Very High Target PowerDensities. Surface and Coatings Technology 122:290–293.

[109] Kraus A (2005) Printed Circuit Board Manufacturers have a Case of DiamondFever. CemeCon AG: Facts 25, Wurselen. 11–12.

[110] Kruger-Sehm R, Fruhauf J, Dziomba T (2008) Determination of the ShortWavelength Cutoff of Interferential and Confocal Microscopes. Wear 264(5/6):439–443.

[111] Kuo PK, Lin MJ, Reyes CB, Favro LD, Thomas RL, Kim DS, Shu-Yi Z, Inglehart LJ,Fournier D, Boccara AC, Yacoubi N (1986) Mirage-effect Measurement ofThermal Diffusivity. I. Experiment. Canadian Journal of Physics 64(9):1165–1171.

[112] Kuo PK, Sendler ED, Favro LD, Thomas RL (1986) Mirage Effect Measurementof Thermal Diffusivity. II. Theory. Canadian Journal of Physics 64(9):1168–1171.

[113] Lampe T, Eisenberg S, Rodriguez Cabeo E (2003) Plasma Surface Engineeringin the Automotive Industry—Trends and Future Prospectives. Surface andCoatings Technology 174:1–7.

[114] Lausmann GA, Unruh J (1998) Die galvanische Verchromung. Leuze-Verlag,Saulgau.

[115] Leupolz A (2003) Multifunctional Automotive Glazing—Examples andTrends. Proceedings Glass Processing Days, 475–478.

[116] Lynam NR (1987) Electrochromic Automotive Day/Night Mirrors. SAE Tech-nical Paper Series, 870636, . 1–9.

[117] Maier K (1996) Zylinderlaufflachen im modernen Motorenbau. Galvanotech-nik 87:1566–1572.

[118] Malshe AP, Yedave SN, Brown WD, Bhat DG, Russel W (2003) Cubic BoronNitride Composite Coating. US Patent, No. 6,607,782.

[119] Matsumura H, Masuda A, Umemoto H (2006) Present Status and FutureFeasibility for Industrial Implementation of Cat-CVD (Hot-Wire CVD) Tech-nology. Thin Solid Films 501:58–60.

[120] Matthai A, Sepeur-Zeitz B, Horstmann F, Schutz J (2006) Intelligent Coatingsfor Automotive Applications. Proceedings of the ICCG 6, 39–42.

[121] Matthews A, Eskildsen SS (1994) Engineering Applications for Diamond-likeCarbon. Diamond and Related Materials 3:902–911.


[122] Mc Bride MW (1990) New Coaters Employing DC Sputtering of SiO2 for theProduction of Optical Components. Proceedings of the 33rd Annual TechnicalConference, Society of Vacuum Coaters, pp. 250–256.

[123] Meneve J, Dekempeneer E, Wegener W, Smeets J (1996) Low Friction andWear Resistant a-C:H/a-Si1�xCx:H Multilayer Coatings. Surface and CoatingsTechnology 86–87:617–621.

[124] Metzner C, Scheffel B, Heinss JP, Roegner FH (2003) Emergent Technologiesfor Large Area PVD Coating of Metal Strips. 46th Annual Technical ConferenceProceedings, Society of Vacuum Coaters, pp. 222–226.

[125] Michler T, Grischke M, Bewilogua K, Hieke A (1999) Continuously DepositedDuplex Coatings Consisting of Plasma Nitriding and a-C:H:si Deposition.Surface and Coatings Technology 111:41–45.

[126] More AS, Jiang W, Brown WD, Malshe AP (2006) Tool Wear and MachiningPerformance of cBN–TiN Coated Carbide Inserts and PCBN Compact Inserts inTurning AlSi 4340 Hardened Steel. Journal of Material Processing Technology180:253–262.

[127] Morimoto T, Tomonaga H, Mitani A (1999) Ultraviolet Ray Absorbing Coat-ings on Glass for Automobiles. Thin Solid Films 351:61–65.

[128] Morimoto T, Sanada Y, Tomonaga H (2001) Wet Chemical Functional Coatingsfor Automotive Glasses and Cathode Ray Tubes. Thin Solid Films 392:214–222.

[129] Munz WD, Schenkel M, Kunkel S, Paulitsch J, Bewilogua K (2008) IndustrialApplications of HIPIMS. Journal of Physics Conference Series 100:082001.

[130] Murakawa M, Komori T, Takeuchi S, Miyoshi K (1999) Performance ofRotating Gear Pair Coated with an Amorphous Carbon Film Under a Loss-of-Lubrication Condition. Surface and Coatings Technology 120–121:646–652.

[131] Murano S (2007) Chancen der organischen Leuchtdioden. Automobil-Elek-tronik ;(August)44–45.

[132] Nakanishi K, Mori H, Tachikawa H, Itou K, Fujioka M, Funaki Y (2005)Investigation of DLC-Si Coatings in Large Scale Production Using DC-PACVDEquipment. Surface and Coatings Technology 200:4277–4281.

[133] Neuville S, Matthews A (2007) A Perspective on the Optimization of HardCarbon and Related Coatings for Engineering Applications. Thin Solid Films515:6619–6653.

[134] Anon. (2003) Klarer Durchblick, MM das Industriemagazin, August 14–15,2003.

[135] Paatsch W (2003) Recent Trends in Surface Finishing for Automobile Industryin Germany. Surface and Coatings Technology 169–170:753–757.

[136] Pies P (2004) mo metalloberflache 58(3):22–25.[137] Podgornik B (2008) in Donnet C, Erdemir A, (Eds.) Tribological Behaviour of

DLC Films in Various Lubrication Regimes, Tribology of Diamond-like CarbonFilms. Springer Science + Business Media, LLC, New York, p. 411.

[138] Prekel H, Klopfstein MJ, Giesselbach M, Patzelt S, Ghisleni R, Lucca DA, GochG, Stock HR (2006) Photothermal Investigation of Ti–Cu–N and T–Ni–N PVDFilms. Annals of the CIRP 55:585–588.

[139] Radojkovic P (2001) Automotive Applications of OLED Displays, ITG-Fach-bericht 165. Vacuum Electronics and Displays 279–282.

[140] Radtke U, Crostack HA, Peppler P, Winschuh E (1993) Untersuchung zurquantitativen Bestimmung thermischer Eigenschaften mittels Warmewelle-nanalyse. Proceedings and Poster, Reports of the DGZfP Jubilee Meeting 1993.Nondestructive Testing. 60 Years of the DGZfP. Experiences and Advantagedfor Europe. Part I, Garmisch-Partenkirchen, Germany: 334–342.

[141] Rauscher G (2005) JOT Journal fur Ober-flachentechnik 45(2):54–56.[142] Reihs K, Malkomes N, Muller P, Renker S, Stahlschmidt O, Claessen R,

Cavaleiro P, Duparre A (2003) Durable Ultra-hydrophobic Glass Coatingswith Optical Quality. 46th Annual Technical Conference Proceedings, Society ofVacuum Coaters, pp. 302–304.

[143] Richter A (2008) Coating’s Holy Grail. Cutting Tool Engineering 60:46–53.[144] Robinson M (2001) Design of the Invisible. Proceedings Glass Processing Days,

45–51.[145] Rosenzwaig A, Gersho A (1976) Theory of the Photoacoustic Effect with

Solids. Journal of Applied Physics 47(1):64–69.[146] Russell WC, Malshe AP, Yedave SN, Brown WD (2003) CBN–TiN Composite

Coating Using a Novel Combinatorial Method—Structure and Performance inMetal Cutting. Journal of Manufacturing Science and Engineering 125:431–435.

[147] Sargent JR, Pickett JE (2006) Accelerated Weathering using Xenon Arc withBoro/Boro Filters, Important Factors for Testing and Translation to Standard58 FL Outdoor Test Protocols. ICCG Proceedings 6, 215–219.

[148] Schafer L, Gabler J (2000) CVD Diamond Tools—Fabrication Methods and ToolApplications. in Bartz W, (Ed.) Proceedings of the 12th International ColloquiumTribology 2000-PlusTechnische Akademie Esslingen, III, Ostfildern, pp. 1855–1859.

[149] Schafer L, Hofer R, Kroger R (2006) The Versatility of Hot-filament ActivatedChemical Vapor Deposition. Thin Solid Films 515:1017–1024.

[150] Schamel AR, Grischke M, Bethke R (1997) Amorphous Carbon Coatings for LowFriction and Wear in Bucket Tappet Valvetrains. Society of AutomotiveEngineers SAE Paper 970004.

[151] Scheibe HJ, Leonhardt M, Leson A, Meyer CF, Stucky T, Weihnacht V (2008)Superhard Carbon Film Deposition by Means of Laser-Arco on the Way fromthe Laboratory into the Industrial Series Coating. Vakuum in Forschung undPraxis 20(6):26–31.

[152] Schmauder T, Nauenburg KD, Kruse K, Ickes G (2006) Hard Coatings byPlasma CVD on Polycarbonate for Automotive and Optical Applications. ThinSolid Films 502:270–274.

[153] Schmidt T, Neumann R, Alers A (2008) Nanotechnology Surface Modificationsfor Anti-fog Applications in Automotive Lighting and Sensor Serial Production.SAE Technical Paper Series 2008-01-1048. 1–5.

[154] Schuhmacher B (2006) Galvanotechnik 97(8):1978–1983.[155] Schuhmacher B, Schwerdt C, Seyfert U, Zimmer O (2003) Surface and Coatings

Technology 163(164):703–709.[156] Schulz U, Lau K, Kaiser N (2008) Antireflection Coating with UV-protective

Properties for Polycarbonate. Applied Optics 47:C83–C87.

[157] Schwerdt C, Riemer M, Kohler S, Schumacher B, Steinhorst M, Zwick A (2004)Stahl und Eisen 124(9):69–74.

[158] Scranton J, Mokerji S, Warchol F (1991) Automated Application of Silicone GlassLike Coatings for Polycarbonate Headlamp Lenses. SAE Technical Paper Series910286. 1–8.

[159] Smit MA, Hunter JA, Sharman JDB, Scamans GM, Sykes JM (2004) CorrosionScience 46:1713–1727.

[160] Straub B (2001) Display Technology for Automotive Applications, ITG-Fach-bericht 165. Vacuum Electronics and Displays 275–278.

[161] Strondl C, Carvalho NM, de Hosson JTM, Krug TG (2005) Influence of EnergeticIon Bombardment on W-C:H Coatings Deposited with W and WC Targets.Surface and Coatings Technology 200:1142–1146.

[162] Szielasko K, Lugin S, Kopp M, Altpeter I (2004) Barkhausen Noise and EddyCurrent Microscopy—A New Scanning Probe Technique for Microscale Char-acterization of Materials. Proceedings of the SPIE, 5392, 105–113.

[163] Szielasko K, Kopp M, Tschuncky R, Lugin S, Altpeter I (2004) Barkhausen-rausch- und Wirbelstrom-Mikroskopie zur ortsaufgelosten Charakterisierungvon dunnen Schichten. Fraunhofer-Institut fur Zerstorungsfreie Prufverfahren(IZFP) DACH, Jahrestagung Salzburg. V13.

[164] Taga Y, Itoh T (1989) Improvement of Abrasion Resistance of SiO2/TiO2

Multilayer Interference Filters. Applied Optics 28:2690–26911.[165] Taga Y (1997) Recent Progress in Coating Technology for Surface Modifica-

tion of Automotive Glass. Journal of Non-Crystalline Solids 218:335–341.[166] Taga Y (1993) Recent Progress of Optical Thin Films in the Automobile

Industry. Applied Optics 32:5519–5530.[167] Takagi K, Makimoto T, Hiraiwa H, Negishi T (2001) Photocatalytic, Antifog-

ging Mirror. Journal of Vacuum Science and Technology A 19:2931–2935.[168] Tang W, Deng LJ, Xu KW, Lu J (2007) X-ray Diffraction Measurement of

Residual Stress and Crystal Orientation in Au/iCr/Ta Films Prepared byPlating. Surface and Coatings Technology 201(12):5944–5947.

[169] Taube K (1998) Carbon-based Coatings for Dry Sheet-Metal Working. Surfaceand Coatings Technology 98:976–984.

[170] Theiner WA, Kern R, Lejeune I (1999) Grundlegende Untersuchungen zurorts- und zeitaufgelosten zerstorungsfreien Bestimmung mikrostrukturellerEigenschaften, Qualifizierung von Laserverfahren. DVS-Berichte 205:81–86.

[171] Tonshoff HK, Karpuschewski B, Mohlfeld A, Seegers H (1998) Influence ofStress Distribution on Adhesion Strength of Sputtered Hard Coatings. ThinSolid Films 332(1/2):146–150.

[172] Tonshoff HK, Mohlfeld A, Spengler C (2001) Pre-treatment of Coated Tools forCutting Applications. The Coatings, Conference Proceedings, 2.1–2.15.

[173] Treutler CPO (2005) Industrial Use of Plasma-deposited Coatings for Com-ponents of Automotive Fuel Injection Systems. Surface and Coatings Technol-ogy 200:1969–1975.

[174] Uhlmann E, Konig J, Durst G, Hilty B, Suuess B (2007) Performance ofDiamond Coated Cutting Tools as a Function of Material Properties. 2ndIndustrial Diamond Conference, Rome, Electronic Proceedings, Diamond atWork Ltd. (Organizer).

[175] Ulrich S, Nold E, Sell K, Stuber M, Ye J, Ziebert C (2006) Constitution of ThickOxygen-containing Cubic Boron Nitride Films. Surface and Coatings Technol-ogy 200:6465–6468.

[176] Umehara H, Takayab M, Terauchia S (2003) Surface and Coatings Technology169/170:666–669.

[177] Unruh J (2007) Galvanotechnik 98(3):591–602.[178] Van der Kolk GJ (2008) in Donnet C, Erdemir A, (Eds.) Wear Resistance of

Amorphous DLC and Metal Containing DLC in Industrial Applications Tribologyof Diamond-like Carbon Films. Springer Science + Business Media, LLC, NewYork , p. 484.

[179] Van Russelt M (2005) Head up Display—From High Tech Jet Fighters to YourCar Windshield. Proceedings Glass Processing Days, 1–3.

[180] VDI Guideline 2840. (2005) 2005–11 Carbon Films—Basic Knowledge, CoatingTypes and Properties. Beuth-Verlag, Berlin.

[182] Veprek S, Veprek Heijman MJG (2008) Industrial Applications of SuperhardNanocomposite Coatings. Surface and Coatings Technology 202:5063–5073.

[183] Vetter J, Barbezat G, Crummenauer J, Avissar J (2005) Surface TreatmentSelections for Automotive Applications. Surface and Coatings Technology200:1962–1968.

[184] Volk P (2006) Galvanotechnik 5(May).[185] Wang L, Prekel H,Liu H, Deng Y, Hu J, Goch G (2009) Thickness Microscopy based

on Photothermal Radiometry for the Measurement ofThin Films. SpectrochimicaActa Part A Molecular and Biomolecular Spectroscopy 72(2):361–365.

[186] Weber M, Bewilogua K, Bialuch I, Keunecke M, Thomsen H, Wittorf R (2006)Carbon Based Coating Systems for Forming Tools. 49th Annual TechnicalConference Proceedings, Society of Vacuum Coaters, p. 529.

[187] Weber M, Bewilogua K, Thomsen H, Wittorf R (2006) Influence of DifferentInterlayers and Bias Voltage on the Properties of a-C:H and a-C:H:Me Coat-ings prepared by Reactive d.c. Magnetron Sputtering. Surface and CoatingsTechnology 201:1576–1582.

[188] Wegricht J, Spindler J, Fels CC (2007) Galvanotechnik 98(6):1371–1379.[189] Wright M, Beardow T (1985) Journal of Vacuum Science and Technology A

4(3):388–392.[190] Wu D, Karpen W, Haupt K, Walther HG, Busse G (1994) Applications of Phase

Sensitive Thermography for Nondestructive Evaluation. Proceedings of the 8thInternational Topical Meeting on Photoacoustic and Photothermal Phenomena inGuadeloupe 21.-25.01.94, Journal de Physique IV, 567–570.

[191] Xi-Cheng W, Fu RY, Li L (2007) Surface and Coatings Technology 201:6922–6927.

[192] Yamamoto H, Matsumoto S, Okada K, Yu J, Hirakuri K (2006) Synthesis of c-BN Films by Using a Low-pressure Inductively Coupled BF3–He–N2–H2

Plasma. Diamond and Related Materials 15:1357–1361.[193] Yang YY, Jin YS, Luo SY (1997) SAM Study on Plasma Sprayed Ceramic

Coatings. Surface and Coatings Technology 91:95–100.


[194] Yao N, Evans AG, Cooper CV (2004) Wear Mechanism Operating in W-DLCCoatings in Contact with Machined Steel Surface. Surface and CoatingsTechnology 179:306–313.

[195] Zanola P, Bontempi E, Ricciardi C, Baruccac G, Depero LE (2004) Character-ization of Silicon Carbide Thin Films Grown on Si and SiO2/Si Substrates.Materials Science and Engineering B-Solid State Materials for Advanced Tech-nology 114:279–283.

[196] Zhang S, Xie H, Zeng X, Hing P (1999) Residual Stress Characterization ofDiamond-like Carbon Coatings by an X-ray Diffraction Method. Surface andCoating Technology 122(December (2/3)):122–129.

[197] Zoller A, Gotzelmann R, Hagedorn H, Klug W, Matl K (1997) Plasma IonAssisted Deposition: A Powerful Technology for the Production of OpticalCoatings, Optical Thin Films V: New Developments. Proceedings of SPIE, 30July–1 August, San Diego, CA, USA, 196–204.

Surface Technology for Automotive Engineering

Documents

Transcript of Surface Technology for Automotive Engineering