All ETDs from UAB

Advisory Committee Chair

Yogesh K Vohra

Advisory Committee Members

Shane A Catledge

Alan W Eberhardt

Jack E Lemons

Document Type

Thesis

Date of Award

2011

Degree Name by School

Master of Science in Biomedical Engineering (MSBME) School of Engineering

Abstract

Disorders of the temporomandibular joint (TMJ) may lead to pain, discomfort and reduced function in many patients. When less invasive treatment methods have been exhausted, a TMJ prosthesis may be used to restore joint mobility and function. Currently available TMJ prosthesis designs feature metal-polyethylene or metal-on-metal wear couples; though these devices have been used to successfully restore joint function, the generation of wear debris may lead to adverse reactions at the implant site (such as inflammation or osteolysis). To further reduce wear and potentially increase the lifetime of these devices, nanostructured diamond (NSD) coatings on the articulating surfaces of Ti-6Al-4V are of interest. NSD coatings synthesized by microwave plasma chemical vapor deposition (MPCVD) feature many desirable properties, including low surface roughness, high hardness, wear resistance, and biocompatibility. Multilayered coatings consisting of alternating layers of NSD and microcrystalline diamond (MCD) may allow for further enhancement of the properties of NSD coatings for biomedical implants. For this study, multilayered diamond coatings composed of alternating layers of NSD and MCD with a top layer of ultra smooth nanostructured diamond (USND) were produced on Ti-6Al-4V alloy by MPCVD. Effects of relative thickness ratios of NSD/MCD and number of layers on surface morphology and structural characteristics of the coatings were studied by X-ray diffraction, Raman spectroscopy, and atomic force microscopy and compared to single-layer coatings of NSD, MCD, and USND. Rockwell indentation was used to qualitatively assess adhesion of the different coatings to Ti-6Al-4V substrates. The multilayered coatings which featured lowest surface roughness and average grain size were shown to have adhesive properties similar to those of single-layer NSD coatings. Scratch adhesion tests were performed on these particular multilayered coatings and compared to single-layered NSD coatings. Critical normal loads were determined for the onset of cohesive failure and adhesive failure of the coating-substrate systems. Mean coating compressive stress was estimated for each coating, revealing the high level of adhesion for NSD and multilayered coatings to Ti-6Al-4V substrates, with single-layered NSD coatings highest overall. Further work, including more advanced tribological testing, could provide additional comparison for the application of multilayered diamond coatings to novel TMJ prostheses.

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