Dissertation
CALCIUM PHOSPHATE AND ZIRCONIA TOUGHENED ALUMINA REINFORCED TITANIUM AND CoCrMo MATRIX STRUCTURES FOR ARTICULATING SURFACES OF LOAD-BEARING IMPLANTS
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000002465
Handle:
https://hdl.handle.net/2376/119653
Abstract
Titanium (Ti) and Cobalt Chromium (CoCr)-based alloys are widely used biocompatible metals for hard tissue repair or reconstruction. Typically, Ti alloys are used at fixation sites, while CoCr alloys are used in load-bearing articulation sites such as in total joint arthroplasty (TJA). The implantation of metallic materials in vivo introduces the possibility of metal ion leaching which has detrimental effects on the physiological environment, such as implant loosening, inflammation, and metallosis, ultimately leading to implant failure. Additionally, the material mismatch with a Ti-based hip stem and CoCr-based femoral head can accentuate taper corrosion and corrosion-influenced modes of failure. For this reason, an ideal metallic-based implant should be corrosion resistant, exhibit high wear resistance, and promote bioactivity in vivo. Three research approaches were investigated to improve the wear, degradation resistance, and biocompatibility of currently used CoCr and Ti alloys. Thus, potentially allowing for the coupling of like materials, i.e., Ti-based hip stem and femoral head to suppress taper corrosion-induced failures. In all three approaches, a ceramic introduction was key in promoting the formation of harder phases or the ability of film formation on the articulation surface to suppress aggressive wear modes or improve upon biocompatibility.In the first study, Ti6Al4V (Ti64) alloy was reinforced with zirconia-toughened alumina (ZTA) and produced by directed-energy deposition (DED)-based additive manufacturing (AM). Produced were metallurgically sound and coherent interfaces, minimal porosity, and bulk structures. Hardness was observed to increase by 27%, normalized wear rate reduced by 25%, and contact resistance increased during in vitro tribological testing along with faster surface re-passivation. In the second study, CoCr alloy (Stellite 6B) was coated with commercially pure Ti (CpTi) and CpTi-Silicon (CoCrTi-Si). Refined carbides and titanium silicides increased the hardness, decreased the wear rate, displayed surface passivation during articulation, and suppressed overall dissociation of Co and Cr ions in vitro. In the third approach, hydroxyapatite (HA) reinforced Ti64 composites were fabricated. Tribological studies revealed an increase in contact resistance due to in situ HA-based tribofilm formation. An in vivo study revealed increased osteoid or new bone presence, thus aiding in increasing shear modulus.
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Details
- Title
- CALCIUM PHOSPHATE AND ZIRCONIA TOUGHENED ALUMINA REINFORCED TITANIUM AND CoCrMo MATRIX STRUCTURES FOR ARTICULATING SURFACES OF LOAD-BEARING IMPLANTS
- Creators
- Jose Avila
- Contributors
- Amit Bandyopadhyay (Advisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 170
- Identifiers
- 99900606857001842
- Language
- English
- Resource Type
- Dissertation