Browsing by Subject "Thin Films"
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Item ANALYSIS OF A FUNCTIONALLY GRADED INTERFACE BETWEEN A NOVEL TITANIUM CARBIDE SURFACE AND TITANIUM ALLOY SUBSTRATE(2023-01-01) Seay, Nathanael; Topoleski, Timmie; Mechanical Engineering; Engineering, MechanicalOsteoarthritis (OA) is a painful and frequently debilitating affliction affecting millions of adults in the United States alone. Historically, treatments for OA focused on relieving symptoms through the employment of drug therapies. However, when drugs are no longer effective, then joint replacement, full or partial, is employed.Despite the success of joint replacements, wear of the bearing surface is of concern. Wear can disrupt the normal mechanical function of the implant and cause numerous problems in the body. Particles can cause allergic reactions, pseudotumors, bone resorption, and aseptic loosening of the implant. Fabrication techniques to make the surface of candidate biomaterials resilient to abrasion and wear continue to be developed. The purpose of this research was to explore a method to determine for improving the lifespan of artificial joints. A novel micro-textured surface was created through plasma enhanced chemical vapor deposition (CVD) on a Ti6Al4V substrate. The interface between the novel titanium carbide surface and substrate was studied to determine its properties relevan to tribological applications. The surface consists of crystalline channels with nanocrystalline features. X-ray diffraction (XRD) patterns indicated that the film was composed of titanium carbide (TiC). Mechanical testing indicated that the film is at least 22% harder than the as received material. Grid based indentation and atomic force microscopy (AFM) fast force mapping indicate that there is an integration zone where mechanical properties vary gradually between substrate and thin film. These results were then used to create a molecular dynamics (MD) model and a finite element model (FEM) to evaluate the potential adhesive properties of the novel surface. The MD model showed that ?mixed interface? specimens have greater adhesion than laminate films. The FEM study indicated that functionally gradient specimens resist crack propagation more than homogeneous specimens. These results indicate that the novel surface could improve the life span of artificial joints.Item Selective Deposition of Metal Oxide Thin Films on Silicon Using Self-Assembled Monolayer Resists(2008-02-12) Link, Daniel Oscar; Gougousi, Theodosia; Physics; Physics, AppliedSelf-assembly refers to the organization of similar components in an ordered fashion, without manual manipulation. Octadecyltrichlorosilane (OTS) (CH3(CH2)17SiCl3) is a type of self-assembling molecule that when adsorbed onto a surface, assembles itself into a close-packed monolayer. The formation of the OTS monolayer on a silicon oxide surface causes a change in the hydrophobicity of the surface and is typically measured using water contact angle measurements. The presence of these molecules can also be monitored using FTIR spectroscopy due to the abundance of C-H bonds. A calibration standard has been found to relate the two measurement techniques as they pertain to this application. The ability of OTS to alter surface chemistry has also allowed us to use it as a resist for the atomic layer deposition (ALD) of metal-oxide thin films. We also investigate the formation of metal-oxide nanostructures using supercritical carbon dioxide assisted deposition (sc CO2) in nanotemplates and how the application of self-assembled monolayer resists can aid in nanostructure production.