2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Thin Film Composite for Friction and Wear Analysis

Jack Stransky

Dr. Sriram SundararajanChris Tourek

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Outline

• Motivation and objectives• Sputter Deposition• Tribometry • Current Status

• Film Deposition• Film thickness measurements – Profilimetry

• Timeline

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Motivation and objectives

• Motivation: to create a thin film composite material which has the best physical properties of its constituents. This coating will be compared to the single material coatings by friction and wear analysis.

• Objective: Create thin film composites using sputter deposition. Materials to be used are:• Tungsten disulfide – Solid state lubricant, high melting point

(1250 C)• Titanium nitride – Extremely hard, protective material

Source: wikipedia.org

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Sputter Coating

• Free e- from electrode are accelerated at Ar atoms, driving e- off Ar, forming Ar+ ions

Source: http://www.ajaint.com/whatis.htm

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Sputter Coating

• Ar + ions are accelerated into negatively charged electrode, blasting target material loose

Source: http://www.ajaint.com/whatis.htm

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Sputter Coating

• Free e- recombine with Ar – ions, causing release of photons causing the glow of the plasma

Source: http://www.ajaint.com/whatis.htm

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Tribometer

• Friction and wear analysis• Friction is determined by applying normal load and

comparing this to the lateral force on the sample. The slope between these is the coefficient of friction.

• Wear is determined by applying a normal force back and forth against the sample and determining the amount of material that has been worn away using profilometry or AFM

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Current status

• Depositing, analyzing, and optimizing properties of films of pure WS2 and TiN

• Using AFM and Profilometer to determine film thickness

• Too much dispersion in samples to obtain accurate film thickness, new samples will be deposited using a method to reduce dispersion between glass and film to better analyize thickness

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Profilometer

Step Height (nm) of WS2

film

270.2

233.5

172.1

192.1

273.8

357.6

437.3

Average = 276.8 nm Standard deviation Surface roughness Ra

276.8 nm 86.3 nm 56.9 nm

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Timeline

This Week

• Deposit and analyze better WS2 coatings• Begin TiN coatings

Week of July 19th

• Deposit and Analyze TiN coatings

• Begin composite film deposition

Week of July 26th

• Begin frictional tests of coatings

Week of August 2nd

• Friction and wear testing

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Extra: AFM

• Currently using AFM to determine film thickness

2010 MoSAIc cohort www.me.iastate.edu/mosaic

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Extra: Ra

• Arithmetic average of absolute values of height deviations from the mean or the average of the peaks and valleys

• A term used to describe surface roughness

• L = evaluation length• Z(x) = profile height function

Source: http://www.harrisonep.com/resources/faq.html#ra