Final Report: 0420482

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Final Report for Period: 07/2004 - 06/2006 Submitted on: 09/19/2006

Principal Investigator: Patten, John A. Award ID: 0420482

Organization: Western Michigan Univ

Title:MRI: Acquistion of Tribometer for Manufacturing/Mechanical Engineering and Materials Research and Education

Project Participants

Senior Personnel

Name: Patten, John

Worked for more than 160 Hours: Yes

Contribution to Project:

Name: Guichelaar, Philip

Worked for more than 160 Hours: Yes

Contribution to Project:

Name: Williams, Molly

Worked for more than 160 Hours: No

Contribution to Project: Molly retired from WMU in 2004 as an Emeritus Professor. She continues to work on and assist us with this project even in herretirement!

Name: Merati, Parviz

Worked for more than 160 Hours: Yes

Contribution to Project:

Name: Joyce, Margaret

Worked for more than 160 Hours: Yes

Contribution to Project:

Name: Ramrattan, Sam

Worked for more than 160 Hours: No

Contribution to Project: Sam is conducting testing for the foundry/casting industry on coatings of mold/cores components.

Name: Fleming, Dan

Worked for more than 160 Hours: No

Contribution to Project: Dan is performing testing on coatings on paper and other products to study friction, wear, and adhesion.

Post-doc

Graduate Student

Name: Joseph, Roshan

Worked for more than 160 Hours: Yes

Contribution to Project: Roshan is the primary person (student) responsible for the maintenance and operation of the equipment. He assists faculty andother students to design, set up and conduct their experiments.

Name: Bhatt, Bis

Final Report: 0420482

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Worked for more than 160 Hours: Yes

Contribution to Project: Bis works with Prof. Patten to design, build, and conduct experimental procedures specifically dealing with the ductile to brittletransition in ceramics and semiconductors such as SiC.

Name: Kattumenu, Ramesh

Worked for more than 160 Hours: Yes

Contribution to Project: Ramesh is the graduate student overseeing the day to day operation and maintenance of the system. He is a PhD student and willdevelop his disseration around use and application of the tribometer.

Name: Jacob, Jerry

Worked for more than 160 Hours: Yes

Contribution to Project: Jerry works with Bis asisting with experiments on SiC materials.

Name: Ravindra, Deepak

Worked for more than 160 Hours: Yes

Contribution to Project: Deepak has been trained to operate the micro tribometer. He will begin to use the instrument for his research starting in the fall of2006.

Undergraduate Student

Technician, Programmer

Other Participant

Research Experience for Undergraduates

Organizational Partners

Third Wave Systems, Inc.We are working with TWS on a DOD MDA ABL funded project to perform some testing on CVD coated SiC using the tribometer

Center for Tribology ResearchCETR provided the micro Tribometer. In addition to a discount on the equipment purchase, they provided on-site training, provided (at nocost) some equipment enhancements (higher resolution digital camera and sample holders) and have been helpful with collaborating onresearch projects.

Mound Laser & Photonics Center, Inc.Mound has supplied some laser machined samples (CVD SiC) that we are testing and evaluating with the tribometer to study the ductileresponse of these processed samples.

Raytheon CompanyRaytheon has provided CVD coated SiC samples for testing to evaluate the ductile response of this material.

Poco GraphitePoco is provided CVD coated SiC samples for testing.

CoorstekCoorstek is providing various SiC samples for testing.

Final Report: 0420482

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RAPT Industries, Inc.RAPT is providing polishing services for CVD SiC materials/samples.

KAZAK COMPOSITES INCWe performed a series of tribology tests/evaluations on a number of composite samples. Friction and wear, under dry conditions, werespecifically addressed. Kazak funded this work during the summer of 2006.

Other Collaborators or ContactsOther contacts and potential collaborators: Goodrich Whirlpool SPX (Comtrex) Transmatic University of Louisiana Lafayette Novelis Tech. Center Omni Tools

Activities and Findings

Research and Education Activities: (See PDF version submitted by PI at the end of the report)We acquired the instrument in February 2005. It was delivered and installed Feb. 9-11. We are now very familiar with the equipmentoperation (hardware and software). Graduate students have been hired, trained, and assigned to work on the equipment. Numerous experiments have been performed and others are being planned and materials and supplies are being procurred to perform additionaltesting. A story was developed for the MiBiz (business) publication about the acquisition of the tribometer. This ariticle will got the word out about theinstrument and our new capabilities. See attached file. A number of companies/organizations have already contacted us about using the instrument to perform tests and experiments; these include:Goodrich, Whirlpool and SPX (Comtex), SII/Omni tool and others. Several enhancements/upgrades to the system have been made to extend its capabilities. Two projects were recently completed in cooperation with TWS. A major project (Phase II SBIR) and a minor project (Phase I SBIR) utilizedthe micro tribometer extensively to study the ductile behavior (ductile regime machining) of CVD SiC and quartz. A project was recently successfully completed for Kazak Composites summer 2006) to study the friction and wear of a number of combinationsof composite materials. Additional funding (appoximately $50,000; over and above the original project amount) was secured this past year to upgrade the instrumentwith nanoindentation capabilities. The nanoindenter option was purchased and delivered this summer (2006) and is being installed the week ofSeptember 5 2006. The nanoindenter option will greatly increase the usefulness of the instrument and permit us to further extend our researchinto the nano technology regime.

Findings: (See PDF version submitted by PI at the end of the report)See attached report.

Final Report: 0420482

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Major Findings: Ductile response and the ductile to brittle transition (DBT) has been studied and evaluated for silicon carbide (SiC). For CVDcoated SiC, depths below approx. 50 nm result in a purely ductile or plastic response in this nominally hard and brittle material. For penetrationdepths > approx. 500 nm, the deformation of SiC is predominantly brittle fracture. Catastropic failure occurs at a penetration depth of approx.600 nm. Force and acoustic emission data confirm the DBT as a function of depth. This information was used to produce a 6' dia. CVD SiC mirror for a DOD SBIR project (the tribometer was actually used as a diamondturning machine to produce the part). In addition to SiC, work has begun on Quartz to identify if a ductile mode exists, and if so to establish its ductile to brittle transition depth. Aductile response was identified, and the DBT depth was found to be 120 nm. Additional experiments are planned to tests the machinability ofQuartz in the ductile regime. Based upon the work on CVD SiC and quartz we were able to obtain a Phase II DOD SBIR (MDA-ABL) in cooperation with Third WaveSystems to further advance our research and technology development. This project was awarded during the summer of 2006 and work willcommence in the fall of 2006 and last for approximately two years. We performed some 'proof of concept' experiments in cooperation with Mound Laser to study the combination of laser machining followed bysingle point diamond turning (SPDT), using the micro tribometer as a diamond turning machine (DTM). The preliminary results were quiteencouraging (reduced tool wear and improved surface finish), which led to the submission of an NSF SBIR Phase I proposal. If funded, theproject will pursue researching the combined laser and SPDT machining processes.

Training and Development:Six students and five faculty members have been trained on the use and operation of the equipment so far. Additional faculty and students willbe trained in the near future as needed.

Outreach Activities:An ariticle appeared in MiBiz describing the instrument and the experimental program (attached to final report as a pdf file). This article hasgenerated additional interest from local industries.

Journal Publications

Patten, Bhatt, "Single Point Diamond Turning of CVD coated Silicon Carbide", HPPT Workshop 2005, p. , vol. 3, (2005). Accepted

Patten, "Ductile Response of Silicon Carbide, Evidence of a High Pressure Phase Transformation?", HPPT Workshop, p. , vol. 3, (2005).Accepted

Patten, Jacob, Bhatt, "Comparison of Experiments and Simulations under Nano-Machining of Silicon Carbide", TWS Users Conf, p. 1, vol. 1, (2005). Published

Bis Bhatt, John Patten, Jerry Jacob, "Single Point Diamond Turning of CVD SiC", ASME MSEC 2006, p. 1, vol. 1, (2006). Accepted

Bis Bhatt, "DUCTILE REGIME NANO-MACHINING OF POLYCRYSTALLINE SILICON CARBIDE", MS thesis, p. 1, vol. 1, (2005). Published

Jerry jacob, "Numerical and Experimental evaluation of the ductile regime machining of silicon carbide", MS Thesis, p. 1, vol. 1, (2006).Published

John Patten, Bis Bhatt, "Ductile Regime machining of CVD SiC", NSF Grantees Conference, p. 1, vol. 1, (2006). Published

John Patten, Jerry Jacob, "Numerical and Experimental evaluation of 3-D ductile regime scratching of CVD SiC", TWS International User'sConference, p. 1, vol. 1, (2006). Published

Bis Bhatt and John Patten, "Ductile Regime Nano-Machining of Poly crystal Silicon Carbide ", ASPE Annual Conference, p. 1, vol. 1, (2005). Published

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Books or Other One-time Publications

Web/Internet Site

URL(s):http://www.micro.physics.ncsu.edu/publication/search/getFileAction?fileref=2005-08-11%2013:54:37&dbfilename=HPPT%20workshop%20poster%20presentation.ppt#1Description:The link to a poster presented at our NSF FRG HPPT conference reviews the major activitities and findings of our work on the tribometerduring the first 6 months of use.

Other Specific Products

Contributions

Contributions within Discipline: We have been able to identify a ductile to brittle transition (DBT) in CVD silicon carbide (SiC). The material exhibited a significant transitionto brittle fracture at a depth of penetration of around 600 nm. The DBT occurred in the wake of the tool, i.e. in the trailing stress field. ThisDBT depth establishes the upper (max)limit or upper bound for ductile material behavior in this ceramic material. This information isimportant for establishing manufacturing process parameters used to form and machine the material. The actual DBT was established to be450-500 nanometers for the materials evaluated (Poco Graphite and CoorsTek). This information was used to establish the successful dutileregime processing parameters that lead to the production of a 6' dia. CVD SiC optic (mirror) for an SBIR Phase I project. We similarly identified a DBT in quartz, at around 120 nm depth of penetration (critical depth of cut). This information will be used to establishsuitable ductile-regime processing conditions for a Phase II SBIR project to be done in cooperation with TWS (2006).

Contributions to Other Disciplines: Establishing the DBT in CVD SiC is important to the design and greater manufacturing community. Products manufactured from SiC, such asoptical components (mirrors and lenses/windows), microelectronics, and structural ceramics, rely on the integrity of the finished project not tofail during use. Minimizing the fracture damage during manufacturing procesing can contribute greatly to the service life of final products.

Contributions to Human Resource Development: We have trained four engineering students, and have involved an additional 2-3 students in projects using the Tribometer. We also hired andtrained an undergraduate student this summer (as an REU) who will hopefully stay on for graduate school and work on the Tribometer research. Through collaboration with our partners, we have added to and extended their knowledge and understanding of fundamental contact mechanics,including friction, wear, plastic deformation and brittle fracture, which will help them and their companies/organizations to advance their work,products, and services.

Contributions to Resources for Research and Education: The purchase of the micro Tribometer significantly enhanced our tribology research and laboratory capabilities (by extending our equipmentcapability into the nano-micro regime). This equipment has also attracted substantial interest from outside the university, such as companiesand research institutions, that want to pursue collaboration with us using the tribometer. This activity certainly enhances our college'sreputation within the larger academic and industrial community.

Contributions Beyond Science and Engineering: One of our partners, TWS, will eventually commercialize the results of our research in their products. It is anticipated that our othercollaborators, and potential partners, will similarly develop superior products or services based upon work on the Tribometer, which willeventually lead to a broad benefit to society through the delivery of new and improved products.

Categories for which nothing is reported: Any Book

Any Product

ABL Report 03

Single point diamond turning of CVD coated Silicon Carbide: Experimental setup

Figure 1: Experimental set up for turning CVD coated Silicon Carbide Sample: CVD coated Silicon Carbide plate 2 inch diameter (Poco Graphite Inc.) Initial surface roughness : <10nm polished.

Sample immersed in polishing fluid Tool clamped on the holder Fixture to hold sample

Cutting Direction

Tool used: Single crystal diamond tool with 3mm nose radius (Chardon tool) Machining time: 7 hours Lubricant used: Master polish (polishing fluid) Machining parameters

Weight applied in grams Depth of cut in mm Spindle speed in rpm Feed speed in mm/sec Feed in mm/rev Cutting speed in

mm/sec 8.22 0.0005 120 0.001 0.0005 0.48

Table 1: Showing machining parameters Incremental loads from 1g to 8g was applied for 1mm radius from the center of sample (ref fig 2). This was done to prevent the tool and the work-piece from any kind of damage.

Results:

Figure 2: CAD representation for surface roughness achieved after machining on the sample

The tribometer used for turning CVD coated Silicon Carbide is a load based machine, the depths specified in table 1 are calculated depths (ref appendix 1). The actual depths of cuts were measured during post experimental analysis using a white light interference microscope. The actual depths were found to be 140nm. The blue band in figure 2 shows the area where the tool was cutting dry against the sample. As the tool moved out from the center of the sample it continuously pushed the fluid away resulting in some dry cuts.

Appendix

Figure 3: Showing the calculated cross-sectional chip area

For depth of cut 0.0005 mm the chip cross-sectional area calculated is 2.4898 x 10-7 mm2 (using MATLAB) Cross-sectional area, A = 3.039 x 10-7 mm2 Cutting force, Fc = 0.01 N (using previous experiments – inclined plane exp) Cutting Energy, Esc = Fc / A = 32.905 N-m/mm3 Using the above calculated cutting energy the weights required for machining silicon carbide were determined. For 500nm depth of cut: Chip cross-sectional area, Ac= 2.4898 x 10-7 mm2 Cutting force, Fc = Esc x Ac= 8.22 x 10-3 N COF = 0.1 (assumed from previous work) Thrust Force, Ft = 8.22 x 10-2 N Weight required, w = 8.22 gram

We have performed a number of scratch tests to determine the ductile to brittle transition (DBT) depths for CVD coated polycrystalline silicon carbide. Experimental set up: These experiments have been carried out using the “Universal Micro-Tribometer (UMT)”. The experimental set is as shown in figure 1 below.

Figure : Experimental set up

Procedure: Experiments were carried out for two samples that we had from two vendors Poco Graphite and Coors Tek. These two samples where CVD coated and then polished to scales which are shown in the table below.

Vendor Original surface

roughness (in nm)

Surface roughness after polishing (in nm)

Poco Graphite 1200 <100 Coors Tek 675 <10

The samples were polished because according to our calculations the DBT depths were in the range of 40-50nm. Unless we polish the samples to such scales it is difficult to interpret results. The scratches were done using a diamond stylus with 5 µm radius. This diamond stylus was moved over a span of 5mm on the sample with loads increasing at uniform intervals using the load control mode in UMT. The loads were varied from 1 to 10 grams for the Coors Tek sample and 10 to 25 grams for the Poco Graphite sample. The post experiment analysis was done using an interference microscope “Wyko vision 32” to acquire the scratch depths and surface morphology.

Sample

Results: Poco Graphite sample: The maximum scratch depths for the Poco sample achieved were 600nm, which can be seen in figure 2 below. We believe that depths beyond this would be brittle. There are two areas on the surface of a sample where ductile to brittle transition can take place. One is in front of the tool (at lower depths) and one is behind the tool (at higher depths). The DBT depth as shown in this sample certainly is behind the tool as the depths are around 600nm, which are in a ratio of 1:10 with the calculated results. This gives us a maximum threshold of the DBT depths.

Figure 2: Wyko image for deeper end of the scratch for Poco sample - loads 10 to 25 gms

Scratch profile showing the depth of scratch at deeper end - Poco Graphite sample

(10 to 25 gms load)

-0.8

-0.6

-0.4

-0.2

091.03 96.03 101.03 106.03 111.03

Z-profile in micro-meters

Y-p

rofil

e in

mic

ro-m

eter

s

Figure 3: Profile of the scratch showing the exploded view of Y-profile from figure 2.

Figure 3 also shows how the wear on the tool tip is as this was not a new tool that was used. We can clearly see the wear on one side of the tip and other side is sharp. The peaks seen in the X-profile of figure 2 suggest that there is brittle fracture at these depths as there should not be any peaks in that area x-profile should also show the scratch depth at that point so instead of moving up should dip. We also measured the force and the acoustic emission data using the UMT. These are shown as below:

Figure 4: Force and acoustic emission data for Poco sample

Fx – scratching force Fz – Load applied AE – acoustic emission data

The encircled region is where we can see a peak with the acoustic emission (AE) data when there is a slight dip in force. This happens at loads around 17 gms The coefficient of friction was also recorded for the test as shown in figure 5.

Figure 5: Coefficient of friction of Poco sample. From figure 5 we can interpret that the value of coefficient of friction is in the range of 0.06-0.09, which is reasonable from past experiences. Coors Tek sample: The maximum scratch depths achieved in the Coors sample was around 140nm. We have not seen any DBT in this range. This material looks ductile even at these scales. Figure 6 gives us the Wyko image of the scratch, which is blown up in figure 7. We can see that at the depths of 130nm this scratch is ductile and there is no sign of brittle behavior, which is obviously for us a very encouraging result. The red circle on the y-profile in figure 6 is represented to show the scratch and the arrow points out the magnified view. We also measured the force and acoustic emission data for this scratch to analyze the ductile to brittle mode. Figure 8 shows us the force and AE data we do not see a peak in AE data, as there is no brittle mode. Whatever peaks we see in AE data are probably due to the noise that is prevalent to experimental conditions.

Figure 6: Wyko image for deeper end of the scratch for Poco sample - loads 10 to 25 gms

Figure 7: Profile of the scratch showing the exploded view of Y-profile from figure 6.

Scratch profile showing the depth of scratch - Coors tek sample (1 to 10 gms load)

-0.16

-0.12

-0.08

-0.04

059.54 60.54 61.54 62.54 63.54 64.54 65.54 66.54

Z-profile in micro-meters

Y-p

rofil

e in

mic

rom

eter

s

Figure 8: Force and acoustic emission data for Coors Tek sample

The coefficient of friction was also recorded for this scratch, which is shown in figure 9 below.

Figure 9: Coefficient of friction for Coors Tek sample

Figure 9 gives us a range of friction coefficient from 0.2-1.2, which is much higher than what is usually seen in past.

Future experiments and thoughts: The Poco graphite sample needs to be polished to <10nm so that the DBT depth due to brittle fracture in front of the tool can be determined. As the calculated value is between 40-50nm and the sample having a surface roughness of <100nm makes it too rough to analyze results. The experimentation and analysis done in the above are using a diamond stylus, which has a different geometry from the cutting tools. Considering our goal of diamond turning will CVD coated silicon carbide would only be satisfied if some preliminary tests are conducted using single crystal diamond tools. Experimental matrix for those experiments are being set up and with in a few weeks we are going to try experimenting with the cutting tools which would give us a feel before going into the final turning of this material. Keeping in mind the goal of this project the next set of experiments will be done using a tilt drive to tilt the sample a few degrees and doing a plunge cut with a flat nose single crystal diamond tool.