Date

8-1-2019

Document Type

Thesis

Degree

Master of Science

Department

Mechanical Engineering

First Adviser

Brandon A. Krick

Abstract

The propose purpose of this work is to understand the wear mechanisms under different condition of III-V nitride semiconductor materials (GaN, AlN) under different environmental conditions ,such as the water environmentsubmerged water, the influence ofsubmerged isopropyl alcohol, and ambient airthe higher range of the sliding speed. Previous studies proved the GaN has a ultralow wear which is approaching wear rateshave shown ultra-low wear of GaN with wear rates approaching reported for diamond . [1]. We have already studiedThoughAlthough previous investigations into the influence of sliding speed and humidity have been done, the sliding speeds were relatively low (< 1 m/s) and the influence of water in a fully submerged state has not been done. the influence of the sliding speed, humidity of the environment crystallographic orientation, and coating composition, after comparing the result with the conditions we tested this time, we found the trend of the tribological properties (wear rate and coefficient of friction). In this work, The wear rate atwear rates were measured using a custom built bi-directional reciprocating multi station tribometer. Wear rates were measured using scanning white light interferometry (SWLI) and measured after 20,000 sliding cycles. This work shows that the highest wear rate in submerged IPA is the lowest with a wear rate of 3.15456.659799×10^(-7) (mm^3/Nm) after 50,000 cycles . AmbientThe air group is has a slowestlightly higher wear rate of 5.561.910743454×10^(-7) (mm^3/Nm), and the highest one in submerged water is has the highest wear rate of 13.75461599546×10^(-76) (mm^3/Nm) . different condition is 1.59954×10^(-6) (mm^3/Nm) in the water of 20000 sliding cycles, 3.59799×10^(-7) (mm^3/Nm) in the isopropanol alcohol of 20000 sliding cycles, 5.56454×10^(-7) (mm^3/Nm) in air of 20000 sliding cycles, how is the wear rate changing is still unknown. In this experiment, we use a multi-tribometer, and we do the reciprocating sliding tests to reduce the error. We use the Scanning electron microscope (SEM) for wear scars to check if there is any influence of the band bending. We also use Raman Spectroscopy to test if there any GaON or other chemical composition after the sliding t Under the same load, the wear rate increasesd as the speed increaseds. The lowest coefficient friction found in IPA group about 0.1, the air one and water one hasve a similar coefficient of friction about 0.25. Scanning electron microscopy (SEM) and Raman spectroscopy were used to investigate the effects of shear-induced band bending and changes in chemical composition due to sliding.est.

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