Doctor of Philosophy (PhD)
Due to their corrosion resistance, high temperature stability, high strength, and high hardness, refractory ceramic thin films and coatings have been utilized for surface engineering of mechanical components and mechanical fabrication tools. Adhesion between ceramic thin films and coatings and the substrate is of critical concern for performance and life time of coated systems. In this dissertation, a custom designed and constructed ultra-high-vacuum (UHV) vapor phase deposition system was used for the preparation of ceramic thin films through low-pressure high-density plasma assisted physical vapor deposition (PVD) methods. Deposited thin films were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), instrumented nanoindentation, focus ion beam (FIB) scanning electron microscope (FIB SEM), and transmission electron microscope (TEM). The effective interfacial shear strength between TiN and CrN thin films and their substrates was evaluated through a substrate- tension method and a newly introduced experimental testing method involving FIB script-milling of film/substrate specimens into micro-pillars and instrumented compression testing performed on such micro-pillars. This micro-pillar testing protocol was further used to experimentally demonstrate, for the first time to our knowledge, a size effect in the shear strength in the configuration of confined shear plastic flow of ductile thin layers. This latter experiment furnishes new and fundamental data for micron scale plasticity theories.
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Mu, Yang, "Deposition and Characterization of Ceramic Thin Films and a New Experimental Approach to Evaluate the Mechanical Integrity of Film/Substrate Interfacial Layers" (2015). LSU Doctoral Dissertations. 1427.
Meng, Wen Jin