Review Article: Composite and Nanocomposite Coatings

Journal of Metallurgical Engineering (ME) Volume 3 Issue 1, January 2014 www.me-journal.org doi: 10.14355/me.2014.0301.04

29

Review Article: Composite and Nanocomposite Coatings Z. Abdel Hamid

Corrosion Control and Surface Protection Lab. Central Metallurgical R & D Institute, Cairo, Egypt [email protected] Abstract Composite or nanocomposite coatings, a new branch of deposition that possess unique physical and mechanical properties are formed by mixing two or more dissimilar materials at the micron or nanoscale. Composites are used when a combination of properties is required that cannot be found in a single material. The properties of composite depend upon not only the individual components used but also the morphology and the interfacial characteristics. The nancomposites can exhibit enhanced mechanical, electrical, magnetic, and/or optical properties compared with their conventional micron-scale (or larger) counterparts. Nano-composite materials and coatings therefore offer enormous potential for new applications including: aerospace, automotive, electronics, biomedical implants, non-linear optics, mechanically reinforced lightweight materials, sensors, nano-wires, batteries, bioceramics, energy conversion and many others.

This review presents the scientific framework for the advances in the composite and nanocomposite coatings research, including fundamental composition/property relationships, fabricating techniques, and applications of nanocomposite coatings. Additionally, the co-deposition of various metallic matrices with a great variety of nano-sized powders from hard carbides, oxides, and ceramics are discussed.

Keywords

Composite; Nano Composite; Nanomaterials; Nanoparticles, Ceramic powder; Reinforcement; Deposition Processes

Introduction

The composite and nanocomposite coatings represent a new class of materials, whose mechanical and tribological properties are not subjected to volume mixture rules, but depend on grain boundary effects, and synergetic interactions of the composite constituents owing to the size effect (Catledge A. etal. 2002, Roy R etal. 1986). These materials can be classified as hard, superhard or ultrahard for hardness materials over 20, 40 or 80 GPa, respectively (Veprek S etal. 1999). Hard coatings are used in many applications, for example, cutting and polishing tools,

molds, dies, hard disk and other wear-resistant applications. However, for engineering applications, hardness must be complimented with high toughness, which is a property of equal importance as hardness (Zhang S., etal. 2005, Musil J etal., 2005 and. Voevodin A. A. etal., 2005). The production of nanocomposite coatings can be achieved through the co-deposition of the matrix material containing disturbed particles of powders, fiber or whiskers. There are many tech-niques can be used for nanocomposite fabrication such as electrodeposition (Sautter F.K., 1963), electroless (Gui Y. L. etal., 1993 ), magnetron sputtering (Musil J. etal., 2001) and sol-gel (Lakshmi R. V., etal., 2011). The electroplating and electroless co-deposition techniques are the most common for preparing nanocomposite coatings. Detailed description of applied deposition techniques, mechanisms and influencing factors will be presented in this text.

Electrodeposition Technique

Firstly, electrodeposition technique has been evolved into a mature subject of research and development today due to its wide range of applications. Composite electrodeposition has been identified to be a technologically feasible and economically superior technique for the preparation of such kind of composites. It is well known that insoluble particles or fibers can be co-deposited with metal or alloy to form composite coatings by electrodeposition method. During this process, the powder particles are suspended in a conventional plating electrolyte and captured in the growing metal film.

The electrodeposition of small particles with metals had resulted over the past two decades in a number of attractive industrial applications: large-scale composite plating of systems like Ni-SiC, Co- TiO2 and Zn- Ni- SiO2 (Changgeng X. etal. 1988, Chan R.W, etal. 1996). In 1997, our laboratory group at CMRDI has introduced first contribution to composite coating development through the deposition of high wear resistance composite coatings by Saher group (Shawki

www.me-journal.org Journal of Metallurgical Engineering (ME) Volume 3 Issue 1, January 2014

30

S. etal., 1997). On the other hand, Abdel Hamid, has studied thermodynamic parameters of composite coatings and suggested the deposition mechanism (Abdel Hamid Z., 2001). Following, Abdel Hamid group has investigated the deposition of different composite coatings containing polymers and ceramics such as PTFE, SiC, WC and TiC-Al2O3 powders (Abdel Hamid Z. etal., 2002, Abdel Hamid Z., etal. 1999 and Abdel Aal A. etal., 2006). Shawky et al. (Shawki S. etal., 1997) proved that the electrodeposited Ni-P composite coatings incorporating a variety of inorganic particles can be obtained from Watt’s nickel bath containing sodium hypophosphite. The mechanism of co-deposition of various particles (SiC, Al2O3, quartz and sand) was studied in view of the electro-kinetic charge characterizing the solid particles. Surface active agent such as sodium oleate has been used to improve the mobility of the particles in the plating solution. The purpose was to increase particle content in the coating to attain high hardness values. Special attention was given to the deposition process using SiC particles. The surface morphology, hardness and wear resistance of the composite coatings were determined. Hardness and wear resistance values were maximized by simple heat treatment in air atmosphere which led to the precipitation of the hard Ni3P phase. Sound, coherent and high wear resistance coatings could be produced. Borkar T., et al. deposited nickel composite coatings (Ni– Al2O3, Ni–SiC, and Ni–ZrO2) from Watts bath using direct current (DC), pulsed current (PC), and pulsed reverse current (PRC) (Borkar T., etal. 2011). This study proved that all the coatings exhibited significant improvement in microhardness and wear resistance due to enhanced reinforcement of nanopar-ticles in the coatings as shown in Figs. 1&2.

FIG. 1 MICROHARDNESS OF PURE NICKEL AND NICKEL COMPOSITE COATINGS DEPOSITED BY DC, PC AND PRC

ELECTRODEPOSITION METHODS (Borkar T., etal. 2011)

Abdel Hamid et al. proved that Nickel-polyethylene composites can be produced by electrodeposition technique using Watt’s nickel bath (Abdel Hamid Z. etal., 2002). The properties of the composites such as microhardness, wear and corrosion resistance were

examined and compared with polyethylene-free nickel deposits. An optimum value of polyethylene (30 vol.%) was obtained at 30 gl-1 polyethylene particles in the electrolyte, at 7.5–9 Adm-2 at pH 4 and temperature 50 °C. The microhardness wear resistance and corrosion resistance of the composite were found to be greater than that of free nickel deposits. The surface morphology and distribution of PE particles in the Ni-composite is shown in Fig. 3.

FIG. 2 THE VARIATION OF WEIGHT LOSS FOR PURE NICKEL AND NICKEL COMPOSITE COATINGS DEPOSITED BY DC, PC

AND PRC ELECTRODEPOSITION METHODS (Borkar T., etal. 2011)

FIG. 3 THE SURFACE MORPHOLOGY AND DISTRIBUTION OF

PE PARTICLES IN THE NI-COMPOSITE (ABDEL HAMID Z. etal., 2002).

Recent literature on the electrodeposition of metallic coatings containing nanosized particles was surveyed (Liu Y etal.,2008 and Xue J., etal., 2004). The nanosized particles, suspended in the electrolyte by agitation or use surfactants, can be codeposited with the metal matrix. The incorporated of nanosized particles can improve microhardness and corrosion resistance, modify growth to form a nanocrystalline metal deposit and a shift in the reduction potential of a metal ion. Many operating parameters influence the quantity of incorporated particles, including current density, bath agitation (or movement of work piece) and electrolyte composition. High incorporation rates of the dispersed

Journal of Metallurgical Engineering (ME) Volume 3 Issue 1, January 2014 www.me-journal.org

31

particles have been achieved using a high nanoparticle concentration in the electrolyte solution, smaller sized nanoparticles; a low concentration of electroactive species, ultrasonication during deposition and pulsed current techniques.

Recently, Ni nanocomposite coatings have gained a significant interest as anodes for fuel cell applications (Abdel Aal A., etal. 2008, Abdel Aal A., etal. 2009, Zhang L., 2010, and Lu B., etal. 2010). They were prepared by incorporating of nano-sized metal oxide particles such as TiO2, ZnO or Al2O3 into the Ni matrix by electroless or electrodeposition technique. Ni or its composite as a catalyst was used for electrooxidation of small organic molecules (Abdel Aal A.,etal. 2009, Zhang L., 2010). It was found that the electrooxidation process at the Ni-based catalyst involved the formation of a higher valence Ni oxide which acted as a chemical oxidizing agent. The β-Ni(OH)2/β-NiOOH redox couple acted as an effective electron transfer mediator for the oxidation process (Kim J.W., etal., 2005). Abdel Aal A. etal. demonstrated that the presence of TiO2 nanoparticles deposited with Ni as nanocomposite electrodes improves the electrocatalytic activity and the stability of Ni catalyst towards electrooxidation of methanol, formaldehyde and glucose in alkaline solutions (Abdel Aal A., etal. 2008, Abdel Aal A., etal. 2009). So far, little work has been reported in the literatures concerning the role of nano-sized metal oxides in enhancing the catalytic activity of Ni catalysts. Instead, there are some articles that address the role of some metal oxides in stimulating non- nickel catalysts. For example, Xu C., etal. reported that the addition of oxides like CeO2, NiO, Co3O4 and Mn3O4 promoted the Pd/C for alcohol electrooxidation in alkaline media (Xu C., etal. 2005). Additionally, Wang etal. reported that NiO significantly improves the electrode performance for methanol oxidation in terms of the reaction activity and poisoning resistance (Wang M., etal. 2009). Moreover, the deposition of CoO on a Pt electrode represented prominent electrocatalytic activity towards the mediated electrooxidation of ascorbic acid, glucose and methanol (Helia H., etal. 2010). Oxides of Ni-Cu exhibit low overvoltage for methanol oxidation and act as effective anode materials (Shobha T. etal. 2003). Other metal oxides granted the catalyst antipoisoning ability and improve the kinetic processes, such as MgO (Liu B., etal. 2007, Samant P.V. etal., 1999). Based on the literature survey, it was found that the role of nano-sized metal oxides in enhancing the electrocatalytic activity of Ni as a nanocomposite catalyst has not been studied enough,

this scope needs more investigation.

Z. Abdel Hamid group successfully prepared nano-composite coatings consisting of nickel matrix and Cr2O3 nanoparticles by means of electrodeposition technique onto commercial carbon substrates (Hassan H. B., etal. 2011). The co-deposition of nano-sized Cr2O3 particles in a metal deposit modified the surface morphology of nickel matrix (see Fig. 4). In comparison with Ni/C electrode, the nanocomposite of Nie-Cr2O3/C (7Vf %) showed a higher surface area, catalytic activity and stability towards the electrochemical oxidation of ethanol in 1.0 M NaOH solution. Higher kinetic parameters such as the charge transfer

a

c

b

d

FIG. 4 SEM OF A) Ni FREE Cr2O3/C, AND Ni-NANO Cr2O3/C ELECTRODES PREPARED AT DIFFERENT

CONTENT OF Cr2O3 IN THE BATH: B) 2, C) 5 AND D) 20 g l-1 (Hassan H. B., etal. 2011).

E / mV (MMO)

0 300 600 900 1200

I / m

A c

m-2

0

100

200

300

4001 Vf %II - 3 Vf %III - 7 Vf %IV - 10 Vf %Ni-free Cr2O3 /C

FIG. 5 CYCLIC VOLTAMMOGRAMS OF THE ELECTROCHEMICAL OXIDATION OF 2.0 M ETHANOL AT

NI-FREE Cr2O3/C AND NI-NANO Cr2O3/C (I, II, III & IV ELECTRTODES CONTAINING DIFFERENT VF % OF Cr2O3 IN THE DEPOSITS) IN 1.0 M NAOH AT A SCAN RATE OF 50 mV

S-1 (Hassan H. B., etal. 2011).


32

coefficient and charge transfer rate constant in the redox species of Ni were recorded at Ni-Cr2O3/C (7Vf %) electrode compared with Ni/C electrode. A higher diffusion coefficient of ethanol as well as catalytic rate constant k is obtained at Ni-Cr2O3/C (7Vf %) electrode compared with that obtained at Ni/C electrode. Fig. 5 shows the behavior of the electro-chemical oxidation of different electrodes containing different Cr2O3 contents in 1.0 M NaOH and 2.0 M. Notably, as the amount of Cr2O3 in the prepared electrode increases the oxidation peak current density of ethanol increases up to 7Vf % and then it decreases at 10Vf % Cr2O3 as the Ni particles may aggregate at high content of Cr2O3. So, the best result regarding the highest catalytic activity and the highest oxidation peak current density is obtained with Ni-Cr2O3/C (7Vf %) [327 mA cm-2 at 775 mV] compared with Ni/C [179mAcm-2 at 738 mV] or the other Ni-Cr2O3/C electrodes.

Additionally, Z. Abdel Hamid group have been successfully fabricated Cu–CuO composite films on carbon electrodes via an electrodeposition route from an environmentally safe alkaline electrolyte containing manntiol as a complexing agent (Hassan H. B., etal. 2011). The study proved that the presence of CuO reduces the Cu grain from 24.3 to 11.2 nm as shown in Fig. 6. The electrochemical studies revealed that the performance of Cu–CuO/C composite electrode towards glucose electrooxidation is superior to that of electrodeposited Cu/C electrode in alkaline solution

containing 0.05 M glucose (Fig. 7). Also, its stability with time is better than that of Cu/C electrode. The proposed composite electrode has reasonable sensitivity and selectivity towards glucose electro-oxidation. Owing to its safe and simple fabrication technique, it is recommended to be used for the development of enzyme-free glucose sensors.

The Japanese team has fabricated multiwalled carbon nanotube (MWCNT) composite films by an electro-deposition technique (Susumu A., etal. 2008), and proved that MWCNTs distributed homogeneously across the surface of the film and tightly incorporated

E / m V (MMO)

-600 -300 0 300 600 900 1200

I / m

A c

m-2

-30

0

30

60

90

1201 g L-1 CuO3 g L-1

5 g L-1

10 g L-1

b

E / mV (MMO)

-600 -300 0 300 600 900 1200

I / m

A c

m-2

-30

0

30

601 g L-1 CuO 3 g L-1 5 g L-1

10 g L-1

a

FIG. 7 CYCLIC VOLTAMMOGRAMS OF ELECTRODEPOSITED CU–CUO/C CONTAINING DIFFERENT AMOUNT OF CUO IN

THE DEPOSITION ELECTROLYTE AT A SCAN RATE OF 50 MV S-1 IN: A) 0.25 M NAOH AND B) 0.25 M NAOH + 0.05 M

GLUCOSE ( HASSAN H. B., etal. 2011) .

FIG. 6 SEM IMAGES OF Cu AND Cu–CuO FILMS DEPOSITED FROM A NONCYANIDE ALKALINE

ELECTROLYTE AT 25 °C, 4 A dm−2, 35 g L−1 MANNITOL CONCENTRATION AND CONTAINING DIFFERENT CuO

CONTENTS ( HASSAN H. B., etal. 2011).

a

b

c

d

FIG. 8. SEM IMAGES OF A NI-MWCNT COMPOSITE FILM UNDER: (A) LOW MAGNIFICATION AND (B) HIGH

MAGNIFICATION (Susumu A., etal. 2008).


33

within the deposited Ni (Fig. 8a & b).

Electroless Technique

Due to the success of composite electrodeposits fabrication, similar technology was applied to electroless deposits in the late 1960s in Germany, and the Netherlands and the USA in the early 1970s. Then, successful co-deposition of ultra-fine particles such as metallic powder, carbides, oxides, diamond and polymers with metal or alloy matrix have been reported by (Gui Y. L., etal. 1993) who used an intermediate layer containing finely divided Al2O3 and PVC particles distributed within a metallic matrix. This intermediate layer was deposited using the electroless coating technique. Electroless coating technology is credited mainly to Brenner & Riddell (Brenner A., etal. 1946). By the controlled chemical reduction reaction, the electroless coating chemistry has emerged as one of the leading growth areas in surface engineering and metal finishing etc. In this technique, the composite coatings are produced by co-deposition of fine inert particles into a metal matrix from an electroless bath. The excellent wear resistance of electroless nickel can be further enhanced by co-depositing hard particulate matter with the nickel-phosphorus alloy.

In the recent years, electronics and electrical engineering have faced the problem how to coat dielectrics (glasses, ceramics, polymers), semiconduc-tors and metals difficult to be coated (aluminum and magnesium alloys, titanium, tungsten, molybdenum, etc.). Electroless plating on aluminum and many of its alloys is applied with a view to improve the surface hardness, corrosion protection as well to provide possible welding. Many authors have dealt with the electroless nickel on aluminum due to the relatively low price of aluminum and its alloys. Abdel Hamid Z.etal. have been investigated electroless nickel–phosphorous composite containing, ZrO2, TiO2, and Al2O3 on 6061 Al alloy from acidic bath as seen in Fig. 9 (Abdel Hamid Z. et al. 2002). Fig.9 shows the microstructure of as-cast 6061 Al alloy and the distribution of the different particles on the surface of composite coatings. It reveals a very high volume percent of Al2O3 particles in the deposit if compared with another two reinforced particles. The mechanism of incorporation of reinforced particles was suggested and confirmed in view of zeta potential and the calculated free energy of adsorption of the particles ( ∆Gads) of the composites. The effect of different composites on the mechanical properties of the deposit

such as hardness and wear resistance illustrated that the reinforced particles as well as the heat treatment provide satisfactory improvement in hardness (Fig. 10) and wear resistance of the deposits.

FIG. 10 THE RELATION BETWEEN THE DIFFERENT TYPES OF

COMPOSITE COATING AND MICROHARDNESS (ABDEL HAMID Z. et al. 2002).

Additionally, the incorporation of WC with Ni-P alloys has been investigated by Z. Abdel Hamid et al. (Abdel Hamid Z., etal. 2007). The influence of plating parameters such as WC content, pH, temperature and stirring rate on the content of WC codeposited with Ni–P alloys were investigated. The maximum value of WC (50–55 Vf%) codeposited can be achieved at a particle content of 20 gL−1 in the electrolyte, at pH 5.5–6, temperature 85–90°C and stirring rate of 150 rpm as

FIG. 9. THE MICROSTRUCTURE OF 6061 Al ALLOY AND THE DISTRIBUTION OF THE DIFFERENT REINFORCEMENT

PARTICLES ON THE SURFACE OF COMPOSITE COATINGS. (A) Al 6061, (B) Ni –P, (C) Ni–P–TiO2, (D) Ni–P–ZrO2, (E) Ni–P–

Al2O3 (Abdel Hamid Z. et al. 2002)


34

shown in Fig. 11. SEM and X-ray diffraction revealed that the phase structure of the solid solution cannot be varied by codeposition of WC particles in Ni–Palloys, and it only influences the growth of the crystal planes.

Abdel Aal et al. prepared novel Ni–P composite coatings containing (TiC–Al2O3) powder synthesized by self-propagation high temperature synthesis (SHS) (Fig. 12) on steel substrate using electroless plating technique (Abdel Aal A.,etal. 2007). Incorporation of (TiC–Al2O3) particles in deposited coating significantly improves the corrosion resistance, wear resistance and increases the hardness of deposited layer.

The incorporation of nano sized particles within Ni-P autocatalytic coatings greatly enhanced mechanical properties and corrosion resistance relative to the pure metal. In some cases, embedding particles in electroless deposited metals added entirely new features to the coatings performance, which widened their use in different industries from high technology,

such as tips for earth moving equipments, molds, cutting tools and engine parts (Guo Z., etal. 2003).

The applications of electroless Ni-P alloy coating in engineering could be especially promising; if one notices that the coating can be deposited on any irregularly shaped surfaces and on many substrates including nonconductors. The Ni-P-CB (carbon black) nanocomposite coatings have been successfully deposited on an ABS plastic matrix via electroless plating process for the development of infrared detecting technologies and low infrared-emissivity materials (Xiangxuan L., etal. 2010 ). Fig. 13 shows surface morphology of the Ni–P and Ni–P–CB composite coatings. It reveals the presence of the CB in the Ni–P layer affects the heterogeneity of the surface and increases the number of boundaries between Ni and other particles in the matrix. The incroporated CB grains into the amorphous matrix distinctly enlarge the surface development of the composite Ni–P–CB layer.

FIG. 13 SURFACE MICROGRAPHS OF THE (A) Ni–P AND (B) Ni–

P–CB COMPOSITE COATINGS (XIANGXUAN L., etal. 2010 ).

Mechanism of Nanocomposite Coating

The precise nature of the process of codeposition and the arrival to the cathode of the solid particle was subject to controversy. Within the last 50 years, many theoretical models have been proposed to explain the mechanism used to produce nanocomposite coatings where nano-sized particles are suspended in the electrolyte and co-deposited with the metal. Three main mechanisms were previously suggested (Celis J.P., etal. 1991 ) to explain the difference in the ability to deposit various types of solid particles: electrophoresis, mechanical entrapment and physical adsorption.

The first theoretical model was suggested by Guglielmi where the co-deposition has usually been explained based on adsorption of metal ions on the particles (Guglielmi N., 1972). He reported that electrophoretic attraction is the driving force behind the entrapment of particulates in the growing film and proposed a mechanism of two adsorption steps, a) a

FIG. 12 SEM MORPHOLOGY OF THE PREPARED (TiC–Al2O3) POWDER (Abdel Aal A.,etal. 2007).

FIG. 11 SURFACE MORPHOLOGY OF NI–P WITH, A) WC FREE, B) +5 gl−1 WC, C) +10 gl−1 WC, D) +15 gl−1 WC,

AND E) +20 gl−1 WC (ABDEL HAMID Z., etal. 2007).


35

loose adsorption, which is physical in nature and b) A strong adsorption step that takes into account the electrochemical nature of the process. The physical adsorption step (a) was described by a Langmuir isotherm similar to the approach of adsorption ions. Accordingly, the surface coverage of the particles is a function of their concentration in solution. The strong adsorption step (b) is similar to a Tafel kinetic expression and also includes a term for the loose adsorption. In this step, the particles are irreversibly adsorbed where Faradays law and a kinetic expression for the current described the volume fraction of the deposited metal. Celis et al. (Celis J., etal. 1977 and Celis J., etal. 1987) verified the validity of the model for the deposition of Cu-Al2O3 coating and proposed an improvement over the Guglelmi model based on a statistical approach. They postulated a five-step adsorption process (Fig. 14). a) An adsorbed double layer of cations forms around each particle in the bulk of the solution. b) The particles are transferred by bulk convection to the boundary layer. c) The particles diffuse through the boundary layer to reach the surface of the cathode. d) At the cathode, the adsorbed electroactive cations are reduced. e) When a fraction of the ions originally adsorbed on a particle are reduced, the particle is captured by the growing film.

FIG. 14 THE MODEL FOR THE DEPOSITION OF Cu-Al2O3

COATING DESCRIED BY CELIS ET AL(Celis J., etal. 1977 and Celis J., etal. 1987).

An improvement of Guglielmi's model was postulated by Saher Shawki et al. (Shawki S. etal. 1997). They thought that the inclusion of solid particles depends largely on their mobility and electrokinetic nature in the plating solution. The described mechanism has been designed to elucidate the aspect of the deposition process on the basis of the electrokinetic mechanism. Solid particles in solutions are electrolytically charged by adsorbing ions on their surfaces. The sign and magnitude of the electrolytic charge is known as zeta potential (ζ). The values of zeta potential for different particles were determined in dilute solution at pH of the plating solution containing all the plating species. The mechanism of solid particle electrodeposition could be suggested as follows: positively charged Ni ions in solution are adsorbed on negatively charged solid particles. The particle with adsorbed ions migrates to the cathode where metal ions are reduced to Ni atoms forming the coating with the entrapped solid particle occupying a place in the metal (or alloy) matrix. A schematic diagram illustrating the mechanism is shown in Figure 15.

FIG. 15 SCHEMATIC DIAGRAM OF THE MECHANISM OF SOLID PARTICLE MOBILITY IN THE PLATING ELECTROLYTE (Shawki

S. etal. 1997).

The higher magnitude of the charge on the particle lead to decreasing the amount deposited in the coating. This can be explained on the basis of the following assumptions: - Particle/ion mobility: with high ζ potential, a greater number of Ni ions are adsorbed on the surface of the solid particle. The aggregates of Ni ions surrounding a particle behave as one large charged body suspended in the electrolyte. The mobility of the later formation is, therefore, expected to decrease under the heavy weight of the coupled formation. The result will be a smaller number of solid particles reaching the cathode.

- Relative amount occluded: since Ni ions: surrounding each particle are immediately reduced to Ni atoms at the cathode surface, the relative amount of


36

particles of high ζ potential (quartz, sand) incorporated in the coating will be less than the amount of particles of lower potential (SiC, Al2O3). In solution, the later type of particles is surrounded by fewer Ni ions; the result is high content of particles in the coating (Shawki S. etal. 1997). Kuo et al. explained the co-deposition process basssed on that a particle group could be embedded into the metal matrix when the attraction force between the particle group and electrode is stronger than the removing force (due to agitation) on the electrode (Kuo S., etal. 2004).

Factors Influencing Nanocomposite Coatings

Several factors influence the incorporation of hard and soft particles in a matrix including, particle size and shape, particle charge (zeta potential), the concentration of the particles in the plating solution, the method and degree of agitation beside operating conditions of plating process (such as temperature, current density, pH,etc). The below topics discuss in details the influence of these parameters on the incorporation rate and hence the structure, the morphology and the properties of the coatings.

Effect of Particles Size and Shape

The size of the particles has a definite impact on their incorporation in the matrix. In general, it is recommended that particles size have enough size to settle in the solution yet not so large as to make the deposit rough or make it difficult for them to be held in suspension. Also, the size of the particles should be selected with reference to the thickness of the electrodeposition, as attempts made to incorporate 10 µm size particles in a 7 µm thickness deposit resulted in unsatisfactory deposit and incorporation of 10 µm size particles even in 25 µm thickness deposit physically weakened the deposit (Shreir L.L., 1955). It is suggested that particles in the size range of 2-7 µm might be suitable for codeposition in a matrix.

Particle shape also plays a vital role in determining their incorporation level. It is generally believed that angular shaped particles will have a greater tendency to hold on to the surface upon impingement than round one. However, Apachilei etal. showed that spherical shaped alumina particles resulted in better incorporation than irregular ones (Apachilei I., et.al., 1998). The difference in particle shape also has a bearing on the type of finish of the deposit. Very smooth and rough surface were obtained from small rounded particles and large angular particles, respectively.

Our group at CMRDI studied the effect of particle shape (spherical or rods) (Abdel Aal A., etal. 2009). The study proved that the shape of particle affects not only the co-deposited powder fraction, but also the morphology of coatings. Figure 16 exhibits the SEM morphology of the Ni-W-P-SiC nanocomposite coating electrodeposited from the plating bath containing 5 g/l of rod and spherical shaped SiC powder. It can be seen that SiC nano-rods disperse uniformly and homogeneously and the content of particles is at high level compared with the spherical shaped (Abdel Aal A., etal. 2009).

Effect of Concentration of the Dispersed Particles

Concentration of the dispersed particles in the electrolyte bath also plays a major role in influencing the incorporation level. Incorporation of Al2O3, TiO2 etc particles in nickel electroplating or electroless matrix was studied by many authors (Susumu A.,elal. 2008, Ik-Hyun O. etal. 2005, Chen W., etal. 2010, Zielińska K., etal. 2012, Dong D., etal. 2009, Vaezi M.R., etal. 2008, and Mohajeri S., etal. 2011). They found that the incorporation of particles increase with increase in their concentration in the bath up to critical concentration. With further additions, the particles incorporation decreased, as the particles appeared to agglomerate in the bath and decreasing trend was observed as shown in Fig. 17,18 and 19. This is in a good agreement with the Guglielmi's model, where the concentration of powder (C) and its embedded fraction (α) are related mathematically by following quation:

e 0

0

1exp( )m

MiC A B CnF v k

ηα ρ

= − +

where M is the atomic weight of the electrodeposited metal, i0 the exchanging current density, n the valence of the electrodeposited metal, F the Faraday constant, ρm the density of electrodeposited metal, η the overpotential of electrode reaction, i= i0 exp (Aη) and k the Langmuir isotherm constant, mainly determined by the intensity of interaction between particles and

FIG. 16 SEM IMAGES OF NI-W-P COATING CONTAINING: (A) ROD SiC AND (B) SPHERICAL SiC (Abdel Aal A., etal.

2009).


37

cathode. The parameters ν0 and B are related to particle deposition, and both play a symmetrical role with the parameters i0 and A related to metal deposition. The constants A and B can be seen as the total charge passing through the electrode interface and carried by Ni2+ ions and charged particles during the reaction.

FIG. 17 THE VARIATION OF EMBEDDED WC IN THE MATRIX

WITH DIFFERENT WC CONTENTS IN THE ELECTROLYTES (Susumu A., elal. 2008).

FIG. 18 DEPENDENCE OF Cr2O3 VF% IN THE DEPOSIT ON ITS

CONTENT IN THE PLATING SOLUTION OPERATED AT 50 mA Cm-2, 150 rpm, pH 5 AND 55 °C (Hassan H. B.,etal. 2011).

-10 0 10 20 30 40 50 60 70 80

0

10

20

30

40

TiO2

AlN

Powd

er c

onte

nt in

dep

osit,

wt.%

Powder content in plating bath, g/l FIG. 19 THE VARIATION OF EMBEDDED FRACTION WITH

NANO POWDER CONTENT FOR AlN (Abdel Aal A., etal. 2006) AND TiO2 (Abdel Aal A. , 2008)

Effect Agitation

Agitation of the plating solution is also a key factor in determining particle incorporation. Various methods of agitation employed include circulation by pumping, purging, of air, ultrasonic agitation, and the plate-

pumper technique. In general, if the agitation is too slow (laminar flow), the particles in the bath may not disperse completely, except when their density is low. On the other hand, if the agitation is too high (turbulent), particles will not have sufficient time to get attached to the surface, and this results in poor particles incorporation. Kalantary et.al. have suggested that the laminar-turbulent transition region is the most effective agitation condition to maximize incorporation of particles in electroless composite coatings (Kalantary M. R., et.al. 1993). Mechanical agitation resulted in lesser incorporation due to the directional flow in the bath. Although agitation by nitrogen avoids the directional flow, it does not help decrease the extent of aggregation of nano-sized diamond particles in the bath.

Effect of Additives

Besides the above factors, some special additives such as surfactants, play a major role in deciding the incorporation of second phase particles. These additives are especially important in the incorporation of hard and soft particles like polytertra fluoroethylene (PTFE), graphite, molybdenum disulphite (MoS2) and SiC. Kunugi Y. et.al. have suggested that though surfactant additives enable a higher level of incorporation of PTFE particles (Kunugi Y. et.al. 1990). Abdel Hamid et. al. have used a Zwitterionic Surfactant to increase the incorporation of PTFE with nickel matrix (Abdel Hamid Z. etal. 2003 and Shawki S. etal. 1997), and sodium silicate to increase the incorporation of SiC and Al2O3 in nickel matrix deposited by electroplating process. Wu Y. et.al. have suggested that an electroplating additive Na3Co(NO2)6 can promote the codeposition of the SiC particles, but the Al2O3 and ZrO2 particles can form composite layers without the assistance of the additive (Wu Y, et.al., 2003).

Rudnik E., et.al. studied electrodeposition of SiC particles with nickel matrix in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB) (Rudnik E., et.al. 2010), and proved that SiC incorporation into the composite coating increased with increasing surfactant concentration in the bath. Cationic surfactant inhibited adsorption of cations (Ni2+) and enhanced adsorption of anions (Br−) on the positive charged carbide surface, but Br−/Ni2+ molar ratios for adsorbed ions were higher than in the bath. It was attributed to the CTAB adsorption realized predominantly by hydrophobic interactions between aliphatic chain of the molecule and SiC surface with


38

the positive head group of CTA+ pointed toward the bulk solution. Amadeh A. etal. studied the effect of sodium saccharin and sodium dodecyl sulfate additives on the amount of incorporated WC with Cr electrodeposition (Amadeh A., etal. 2012).

Effect of Electrolyte pH and Particle Charge

The pH value of the electrolyte plays an important role in the co-deposition process. pH is counted as the most effective parameters on zeta potential (ζ) of the powders. Many chemically simple surfaces, such as a SiC dispersed in a dilute salt solution, showed a common pattern when the pH is varied. For the deposition of Ni-Cr2O3 composite coating at different pH values, Hassan H. B., Z. et al. (Hassan H. B., Z. et al. 2011) found that the Vf % of Cr2O3 increases as increasing pH values and attains the greatest value at pH 5-6 (Fig. 20). With further increasing pH larger than 6, the Vf % of Cr2O3 in the deposited layer decreases due to the formation of nickel hydroxide in alkaline medium, which leads to decreasing the deposition rate and consequently decreasing the Vf % of Cr2O3. The deposition behavior of Cr2O3 with pH can be explained by an electrophoresis phenomenon due to the formation of an ionic cloud around the Cr2O3 particles. Electrophoresis is the induced motion of colloidal particles or molecules suspended in ionic solutions that result from the application of an electric field. The electrophoretic velocity is a function of the etectrostatic forces on the surface charge, the electrostatic forces on their electric double layers, and the viscous drag associated with both the motion of the colloidal particles as well as the motion of the ionic cloud the colloidal particles. The sign and magnitude of the electrolytic charge is known as zeta potential (ζ).

Effect of Current Density

Current density of the plating solution plays an important role in the electrodeposition process beside

the amount of embedded reinforcements. Direct current (DC) electrodeposition methods are commonly used for fabrication of metallic as well as composite coatings. The DC electrodeposition methods are often associated with slower deposition rates and coating defects such as surface roughness, porosity, poor adhesion, undesirable microstructure, etc. Recently, pulse current (PC) and pulse reverse current (PRC) electrodeposition methods have attracted significant attention to improve deposition rates and micro-structure of the coatings for better mechanical and corrosion properties (Aperador Chaparro W.A., etal. 2007 and Balasubramanian A., etal. 2009). The effect of current density on the volume percent of the PE (polyethylene) in the Ni matrix has been studied by Abdel Hamid Z. et al. (Abdel Hamid Z., etal. 2002). The data indicated that the volume percent of the PE increased with increasing current density up to 7.5 Adm-2 as shown in Fig. 21. With further increase in the current density, the extent of codeposition of PE decreases.

FIG. 22 EFFECT OF CURRENT DENSITY ON WT.% OF Co

DEPOSITED Si3N4 (Abdel Aal A., etal. 2006).

Additionally, Krishnaveni et al. found that content of

2 3 4 5 6 7 80

10

20

30

40

50

60

V f of C

r 2O3

pH2 4 6 8 10

-40

-30

-20

-10

0

10

Zeta

pot

entia

l, m

V

pH

FIG.20. RELATIONSHIP BETWEEN PH OF THE ELECTROLYTE AND A) VF% OF Cr2O3 IN THE DEPOSITED LAYERS, B) ZETA-POTENTIAL OF Cr2O3 PARTICLES (THE COATING PROCESS OPERATED AT 50 °C, 150 rpm, 7Adm-2

AND 20 gl-1 Cr2O3) (Hassan H. B., Z. et al. 2011).

FIG. 21 EFFECT OF CURRENT DENSITY ON THE VOLUME PERCENT OF PE IN THE DEPOSITS, THE DEPOSITION AT PH 4, 50 °C AND AT 10 gl-1 PE PARTICLES IN THE BATH.

(Abdel Hamid Z., etal. 2002).


39

nano Si3N4 particles increases into Ni-B matrix with increase in current density and reaches a maximum at 1 A/dm2 (Fig. 22), beyond which it decreases (Krishnaveni K., etal. 2008). The observed trend is in agreement with our results in the deposition of Zn-ZnO-TiO2 (Fig. 23) and Ni-SiC nanocomposite (Abdel Aal A., etal. 2006) (Fig. 24).

FIG. 23. EFFECT OF CURRENT DENSITY ON WT.% OF Co-

DEPOSITED TiO2 (Abdel Aal A., etal. 2006).

The explanations of this behavior based on adsorption of ions on the particles, activation and diffusion control of metal deposition, point of zero charge of the particle and fluid flow resistance of the particles have been suggested. Hwang and Hwang have suggested that at low current densities, the particle co-deposition rates are determined mainly by the reduction of adsorbed H+ ion on the particle whereas at high current densities, reduction of both the metal ions as well as the H+ ions becomes important in determining the co-deposition rate of the particle (Hwang B., etal. 1993). Yeh and Wan (Yeh H., etal. 1997) have reported that at low current densities co-deposition of second phase particles in Ni matrix follows Guglielmi’s two-step adsorption model and results in a higher level of

incorporation (Guglielmi N., 1972). At high current densities, Ni ions are transported faster than the second phase particles which are transported by the mechanical agitation. Hence, the co-deposition of second phase particles becomes particle-transfer controlled.

In recent years, many researchers have applied pulse current (PC) instead of direct current (DC) electro-deposition methods for the preparation of composite coatings. Gyftou group proved that specific selection of the pulse current parameters results in the production of composite Ni-SiC electrodeposits with better and predefined properties, higher incorporation percentages and more uniform distribution of the particles in the metallic matrix than those attained by direct current techniques (Gyftou P., etal. 2005). Similar findings were obtained by Steinbach and Ferkel during the preparation of Ni-Al2O3 by PC and DC electrodeposition methods (Steinbach J., etal. 2001). They reported that nanocrystalline Ni-Al2O3 composite coatings can be produced by PC electrodeposition. In contrast to Ni-Al2O3 composite coatings prepared by DC electrodeposition, Al2O3 nano-particles embedded in the nanocrystalline Ni-Al2O3 composite coatings are less agglomerated and a particle size selection of the co-deposited nanoparticles during PC plating takes place.

Characterization and Application of Nano-composite Coatings

Due to their enhanced hardness, wear resistance and corrosion resistance when compared to pure metal or alloy, nanocomposites generally exhibited wide engineering applications in different fields. The amount of incorporated particles is the key parameter for the success of metal matrix composite applications, since it largely determines the composite properties such as wear resistance, corrosion resistance, and hardness when compared with the corresponding values for pure metal or alloys deposits (Lozano-Morales A., etal. 2004). Furthermore, the co-deposition of a sufficient amount of non-agglomerated particles should lead to production of harder and more resistant coatings (Zanella C., etal. 2009). Particle-reinforced composite coatings based on nickel and alumina are applied in different technological fields with high demands on friction and corrosion resistance (Jung A., etal. 2009). Lekka et al. showed that the co-deposition of SiC nanoparticles leads to a more noticeable grain refinement and, as a consequence, the nanocomposite deposits present a

FIG. 24. EFFECT OF CURRENT DENSITY ON VOLUME FRACTION

OF SiC CONTENT IN THE DEPOSITED LAYER (Abdel Aal A.,

etal. 2006).


40

very high microhardness, 61% higher than pure copper deposits, and an increase of 58% of the abrasion resistance (Lekka M., etal. 2009). Future applications of these materials depend on the ability to produce them with controlled composition and properties, using inexpensive and reliable techniques.

Ali Eltoum M.S.et al. proved that the incorporation of titania nanoparticles with Ni matrix obviously affects the surface morphology of the coatings, as shown in Fig. 25 (Ali Eltoum M.S., etal.). The titania particles appear as light spots in the darker nickel matrix. Because of the addition of TiO2 nanoparticles to the bath, the microstructure of the nickel matrix changed from spherical (Fig. 25a) to granular (Fig. 25b).

L. Yan et al. fabricated Ni-SiO2 nano-composite coatings by electrodeposition technique on the AZ91HP magnesium alloy surface (Yan L., etal. 2011). They proved that the Ni-SiO2 nano-composite coatings with uniform crystalline, dense structure can be obtained on AZ91HP magnesium alloy with high wear resistance compared to magnesium alloys and pure nickel coatings.

Wang et al. proved the remarkable increase in the hardness of Ni-ZrO2 composite coatings compared to pure Ni which was attributed to the combination of Hall-Petch strengthening and Orowan strengthening (Wang W., etal. 2005). While Xu R. et al. attributed the higher hardness of Ni-W-P-SiO2, Ni-W-P-CeO2 and Ni-W-P- SiO2-CeO2 nanocomposite coatings to the formation of hard Ni3P phase ( Xu R., etal. 2008). Qu et al. reported that the existence of nano-sized CeO2 particles, as the second phase, reduces the grain size of Ni matrix. Accordingly, the higher microhardness value of the nanocomposites may be due to the incorporation of reinforcement particles and the decrease of the grain size of Ni matrix of the composites (Qu N. et al., 2004). Yang Y. et al. have

been successfully synthesized Ni–P–ZrO2 using electroless method (Yang Y. et al. 2011). They proved that the microhardness of nano-composite coating was improved to∼1,045 HV200 compared to 619 of the Ni–P coating. Consequently, the coating obtains significantly improved wear resistance. Additionally, our group in CMRDI proved that the nano composite coatings are characterized by lower corrosion rate and corrosion current density compared to the conversion coating by electroless or electroplating technique.

Recently, Ni nanocomposite coatings have gained a significant interest as anodes for fuel cell applications (Abdel Aal A., etal. 2009, Abdel Aal A., etal. 2008, and Sattarahmady N., etal. 2010). Fuel cells are an important technology for a potentially wide variety of applications including micro power, auxiliary power, transportation power, stationary power for buildings and other distributed generation applications, and central power. They were prepared by incorporating of nano-sized metal oxide particles such as TiO2, ZnO or Al2O3 into the Ni matrix by electroless or electro-deposition technique. photocatalytic applications using oxides as TiO2 and ZnO have received much attention to solve some environmental problems due to the highest photocatalytic activity, being non-toxic, stable in aqueous solution and relatively inexpensive (Calza P., etal. 1997). Ni or its composite as a catalyst was used for electrooxidation of small organic molecules (Hassan H. B., etal. 2011, Hassan H. B., etal. 2011).

Conclusions

The results of this investigation suggest some general conclusions, which can be summarized as follows:

- The plating parameters such as temperature, pH of the plating solutions, stirring rate, concentration of the reinforcement, and current density have effect on the deposition.

- The inclusion of solid particles depends on their electrokinetic nature (zeta potential, ζ) of the reinforcementsin the plating solution.

- The incorporation of reinforcements in the deposit improves the microhardness, the wear as well as the corrosion resistance of the deposit.

- The hardness of nanocomposite coating depends directly on the Vf% of nano reinforcement.

-Nanocomposite coatings have gained a significant interest as anodes for fuel cell applications.

FIG. 25. SEM OF ELECTRODEPOSITED NI-TiO2 COMPOSITE WHERE, A) PURE NI, AND B) NI-NANO TIO2 DEPOSITED FROM BATH CONTAINING 0.2 M

NiSO4, 0.2 M C6H11NaO7, 0.4 M BORIC ACID OPERATED AT 25 °C , 2.5 Adm-2,AND pH 8 25 (Ali Eltoum M.S., etal.)


41

- Composite and nanocomposite electrodes have catalytic activity towards electrooxidation of glucose in alkaline medium.

- Composite and nanocomposite electrodes enhance catalytic activity and stability towards electrooxidation of the alcohol compared with conventional electrodes used.

REFERENCES

Abdel Aal A., Ibrahim K., and Abdel Hamid Z., Wear, 260

(2006) 1070.

Abdel Aal A., Hassan H.B., Abdel Rahim M.A., Journal of

Electroanalytical Chemistry, 619 (2008) 17.

Abdel Aal A., Hassan H.B., Journal Alloys and Compounds,

477 (2009) 652.

Abdel Aal A., Bahgat M., Radwan M., Surf. Coat. Technol.,

201 (2006) 2910.

Abdel Aal A., El-Sheikh S. and Ahmed Y., Mater. Res. Bull.,

44 (2009)15.

Abdel Aal A., Mater. Sci. Eng. A. 474 (2008) 181.

Abdel Aal A., Zaki Z.I., Abdel Hamid Z., Materials Science

and Engineering A, 447 (2007) 87.

Abdel Aal A., Barakat H., Mohamed M., Appl. Surf. Sci. 254

(2008) 4577.

Abdel Hamid Z., Anti-Corrosion Methods and Materials, 48,

4 (2001) 235.

Abdel Hamid Z., Ghayad I. M., Mater. Lett., 53 (2002) 238.

Abdel Hamid Z. and Omar A.M.A., Anti-Corrosion Methods

and Materials, 46, 3 (1999) 212.

Abdel Hamid Z., Abou Elkhair M.T., Materials Letters, 57

(2002) 720.

Abdel Hamid Z., El Badry S.A, Abdel Aal A., Surface &

Coatings Technology, 201 (2007) 5948.

Abdel Hamid Z. and Omar A.M.A., Journal of Surfactants

and Detergents, 6 (2) (2003) 163.

Ali Eltoum M.S., Baraka A.M., Morsi M.S., Hassan E. A.,

Products Finishing, http://www.pfonline.com.

Amadeh A., Nadali S., Lari Baghal S. M., Moradi H., 2nd

International Conference on Ultrafine Grained &

Nanostructured Materials (UFGNSM), International

Journal of Modern Physics: Conference Series. 5 (2012)

737.

Apachilei I., Duszcyk J., Katgerman L., Overkamp P. J. B.,

Scripta Materialia, 38, 9 (1998) 1347.

Aperador Chaparro W.A., Lopez E.V., Matéria (Rio de

Janeiro) 12 (2007) 583.

Balasubramanian A., Srikumar D.S., Raja G., Saravanan G.,

Mohan S., Surface Engineering, 25 (2009) 389.

Borkar T., Harimkar S. P., Surface and Coatings Technology,

205, 17–18 (2011) 4124.

Brenner A., Rid G., Res. Natl. US Bur. Stand. (1946) 37: 31.

Catledge A., Fries D., Vohra K.,. J. Nanosci. Nanotech. 2

(2002) 1.

Chan R.W. and Haasen P., (Eds), Physical Metallurgy, 4th

revised and enhanced ed., Elsevier Science (1996).

Changgeng X., Zonggeng D., and Lijun Z., Plating and

Surface Finish, 75 , 10 (1988) 54.

Celis J.P., Roos J.R., Buelens C. and Fransaer J., Transactions

of the Institute of Metal Finishers, 69, 4, (1991) 133.

Celis J., Roos J., J. Electrochem. Soc,124 (1977) 1508.

Celis J., Roos J., Buelens C., J. Electrochem. Soc., 134 (1987)

1402.

Calza P., Minero C., Pelizzetti E., Environment. Sci. Technol.,

31(1997) 2198.

Chen W., Gao W., He Y., Surface & Coatings Technology,

204 (2010) 2493.

Dong D., Chen X.H., Xiao W.T., Yang G.B., Z P.Y.hang,

Applied Surface Science., 255 (2009).

Guglielmi N., J. Electrochem. Soc., 119 (1972) 1009.

Gui Y. L., Shou Z., Thin Solid Film, 245 (1993) 98.

Guo Z., Zhu X., Mater. Sci. Eng. A, 363 (2003) 325.

Gyftou P., Stroumbouli M., Pavlatou E., Asimidis P.,

Spyrellis N., Electrochem. Acta., 50 (2005) 4544.

Hassan H. B., Abdel Hamid Z., Int.J. Hydrog. Energy, 36

(2011) 5117.

Hassan H. B., Abdel Hamid Z., Int. J. Electrochem. Sci., 6

(2011) 5741.

Helia H., Yadegarib H., Electrochimica Acta, 55 (2010) 2139.

Hwang B., Hwang C., J. Electrochem. Soc.140 (1993) 979.

Ik-Hyun O., Jae-Young L., Jae-Kil H., Hee-Jung L., Byong-

Taek L., Surface & Coatings Technology, 192 (2005) 39.

Jung A., Natter H., Hempelmann R., Lach E., J. Mater. Sci.,

44 (2009) 2725.

Kalantary M. R., Holbrook K. A., Wells P. B., Trans. IMF., 71,

2 (1993)55.

Kim J.W., Park S. M., Journal of the Korean Electrochemical

Society, 8 (2005) 117.

http://www.pfonline.com/articles/electrodeposition-and-characterization-of-nickeltitania-nanocomposite-coatings-from-gluconate-baths�

http://www.sciencedirect.com/science/journal/02578972�

http://www.sciencedirect.com/science/journal/02578972/205/17�

http://www.sciencedirect.com/science/journal/02578972/205/17�


42

Krishnaveni K., Sankara T, Seshadri S., J. Alloys Compound.

466 (2008) 412.

Kunugi Y., Fuchigami T., Nonaka T., J. Electroanalyt. Chem.,

287 (1990) 385.

Kuo S., Chen Y., Ger M., Hwu W., Mater. Chem., Physics, 86

(2004) 5.

Lakshmi R. V., Bharathidasan T., Bharathibai Basu J.,

Applied Surface Science, 257 (2011) 10421.

Lekka M., Koumoulis D., Kouloumbi N., Bonora P. L.,

Electrochim. Acta, 54 (2009) 2540.

Liu Y., Ren L., Yu S., Han Z., Journal of University of

Science and Technology Beijing, Mineral, Metallurgy,

Material, 15, 5 (2008) 633.

Liu B., Chen J.H., Xiao C.H., Cui K.Z., Yang L., Pang H.L.,

Energy Fuels, 21 (2007) 1365.

Lozano-Morales A., Podlaha E.J., J. Electrochem. Soc., 151

(2004) C478.

Lu B., Bai J., Bo X., Zhu L., Gu L., Electrochimica Acta, 55

(2010) 8724.

Mohajeri S., Dolati A., Rezagholibeiki S., Materials

Chemistry and Physics, 129 (3) (2011) 746.

Musil J., Baroch P., Vlcek J., Nam K. H., Han J. G., Thin Solid

Films, 475 (2005) 208.

Musil J., Vlˇcek J., Surface and Coatings Technology, 142-144

(2001) 557.

Qu N., Chan K., Zhu D., Scripta Mater., 50 (2004) 1131.

Roy R, Roy RA, Roy DM. Mater. Lett. 4(8-9) (1986) 323.

Rudnik E., Burzynska L., Dolasinski Ł., Misiak M., Applied

Surface Science, 256 (2010) 7414.

Samant P.V., Fernandes J.B., Journal of Power Sources, 79

(1999) 114.

Sattarahmady N., Heli H., Faramarzi F., Talanta, 82 (2010)

1126.

Sautter F.K., J. Electrochem. Soc. 110 (1963) 577.

Shawki S. and Abdel Hamid Z., Anti-Corrosion Methods

and Materials, 44, 3(1997)178.

Shobha T., Aravinda CL., Devi L.G., Mayanna S.M., Journal

of Solid State Electrochemistry, 7 (2003) 451.

Shreir L.L., Indust. Finish., 8, 326 (1955) 389.

Steinbach J., Ferkel H. , Scripta Mater., 44 (2001) 1813.

Susumu A., Akihiro, F., Masami, M., Morinobu, E.,. Mater.

Lett., 62 (2008) 3545.

Vaezi M.R., Sadrnezhaad S.K., Nikzad L., Colloids and

Surfaces A: Physicochemical and Engineering Aspects, 315 (1–3) (2008) 176.

Veprek S., Vac. J., Sci. Technol. A, 17 (1999) 2401.

Voevodin A. A., Zabinski J. S., Muratore C., Tsinghua

Sci.Technol. 10 (2005) 665.

Wang W., Hou F. , Wang H., Guo H. , Scripta Mater., 53

(2005) 613.

Wang M., Liu W., Huang C., International Journal of

Hydrogen Energy, 34 (2009) 2758.

Wu Y, Ghang D. Y., Kwon S. C. and Kim D., Plat. Surf.

Finish., 2 (2003) 46.

Xiangxuan L., Chun W., Xuanjun W., J. Coat. Technol. Res., 7

(5) (2010) 659.

Xu R., Wang J., He L., Guo Z., Surf. Coat. Technol., 202 (2008)

1574.

Xu C., Tian Z., Shen P., Jiang S.P., Electrochimica Acta, 53

(2008) 2610.

Xue J., Zhu, D., Zhao, F., J. Mater. Sci., 39 (2004) 4063.

Yan L., Si-rong Y., Jin-dan L., Zhi-wu H., Dong-sheng Y.,

Trans. Nanoferrous Met. Soc. Chain, 21 (2011) s483.

Yang Y., Chen W., Zhou C., Xu H., Gao W., Appl Nanosci., 1

(2011) 19.

Yeh H., Wan C., Plat. Surf. Finish. 84 (3) (1997) 54.

Zanella C., Lekka M., & Bonora P. L., J. Appl. Electrochem.,

39 (2009) 31.

Zhang L., Li F., Applied Clay Science, 50 (2010) 64.

Zhang S., Sun D., Fu Y., Du H., Surf. Coat. Technol. 198 (2005)

2.

Zielińska K., Stankiewicz A., Szczygieł I., J. Colloid and

Interface Science, 377 (1) (2012) 362.




Review Article: Composite and Nanocomposite Coatings

Documents

Transcript of Review Article: Composite and Nanocomposite Coatings