Degree Type

Dissertation

Date of Award

2016

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

Major

Mechanical Engineering

First Advisor

Pranav Shrotriya

Abstract

The use of the hybrid laser waterjet heat (LWH) treatment process to develop super-hard materials is a new field of research that has the potential to develop materials with hardness characteristics that compare with or exceed that of diamond. The research presented in this dissertation investigated the hardness improvement mechanism of boron nitride (BN) materials by investigating the optimization of LWH process parameters and studying the microstructural refinement of BN materials. The study of the LWH system parameters investigated the relationship between LWH system parameters and the BN materials’ hardness change ratio. Upon the study, the optimal LWH system parameters (laser fluence, laser beam overlap percentage, boron nitride composition, laser pass number, and laser intensity) were identified in order to maximize BN material hardness. For the BN material microstructure refinement study, scanning electron microscopy (SEM), Raman spectroscopy, and finite element methods (FEM) were used to investigate the microstructure of pre- and post-LWH-treated BN materials. Analytical and experimental approaches were conducted throughout all of the studies, and a variety of analysis techniques were applied. Results indicate that LWH treatment is a feasible approach to improve the hardness of select materials while providing a potential method to develop new super-hard materials for the tooling industry.

DOI

https://doi.org/10.31274/etd-180810-5481

Copyright Owner

Jingnan Zhao

Language

en

File Format

application/pdf

File Size

123 pages

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