Semester of Graduation

Fall 2021

Degree

Master of Materials Science and Engineering (MMatSE)

Department

Mechanical Engineering

Document Type

Thesis

Abstract

The high residual stresses within diamond-like carbon (DLC) films limit its thickness and make the film tend to delaminate from the substrate and be defective on the surface. To address this problem, a new plasma enhanced chemical vapor deposition system (PECVD) was set up to investigate the effects of different film growth parameters on the DLC films, such as chromium doping, gas fluxes, depositing pressures, bias voltages, and depositing times. After the film growth parameters were optimized, this condition was transferred from silicon wafer to SS316 steel plate to deposition of DLC films with some adjustments. Scanning electron microscopy (SEM) images were taken to check the surface of these DLC films. Cross-sectional SEM images were taken by cutting the DLC films with focused ion beam (FIB). Young’s modulus and hardness of the DLC film were measured by instrumented nanoindentation. Multilayer DLC films with three Cr/Cr-DLC bilayers were deposited. Pure Cr interlayers were introduced to DLC films to improve its fracture toughness. Bending test of V-notched microbeams was performed on a film with a single layer of DLC and a DLC film with three Cr/Cr-DLC bilayers. The results show that by introducing more Cr interlayers in a DLC film, its fracture toughness was improved several times higher than that of a single layer DLC film.

Committee Chair

Wen Jin Meng

DOI

10.31390/gradschool_theses.5474

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