Nanocrystalline Diamond Deposition for Friction Applications

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Title: Nanocrystalline Diamond Deposition for Friction Applications
Author: Winfrey, A. Leigh
Advisors: J.E. Rowe, Committee Chair
R.J. Nemanich, Committee Co-Chair
O.E. Hankins, Committee Member
Abstract: The structure and morphology of nanocrystalline diamond films, grown on single side polished silicon (100) wafers by microwave plasma assisted chemical vapor deposition in Ar-H-CH4 plasma, with varying hydrogen concentrations, were analyzed and examined using Raman spectroscopy, scanning electron microscopy, atomic force microscopy, near edge x-ray absorption fine structure spectroscopy, and x-ray diffraction. Visible Raman spectra, XRD data, and NEXAFS spectra exhibit fingerprints for NCD films. Broad bands at 1350 and 1520-1580 cm-1 with shoulders at 1100-1150 cm-1 and 1430-1470 cm-1 and a shoulder at 1150cm-1 are evident in the Raman spectra. The XRD analysis reveals small grain sizes, 5 to 10 nm. The NEXAFS spectra discussed in this thesis are similar to characteristic NCD spectra in the literature and show distinct diamond character. Friction performance was studied using Pin-on-Disk and Reciprocating sliding tribometry with sapphire counterfaces. Tribological performance of nanocrystalline diamond coatings was not influenced by coating roughness over the range studied (20 — 60 nm); however, the coating performance was influenced by coating chemistry. High friction run-in was minimized and a low final friction coefficient <0.05 was measured. These coatings exhibited good wear resistance for sliding against sapphire hemispheres. Their performance was correlated to their properties and structure, which were also studied. Plasma modeling and optical emission spectroscopy revealed plasma parameters, electron plasma temperature and number density, consistent with published results.
Date: 2007-12-07
Degree: MS
Discipline: Physics

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