Thesis
IMPROVING WEAR PERFORMANCE AND BACTERICIDAL ACTIVITY OF Cu AND HYDROXYAPATITE REINFORCED CoCrMo IMPLANTS
Washington State University
Master of Science (MS), Washington State University
07/2024
DOI:
https://doi.org/10.7273/000007074
Abstract
Cobalt-chromium (CoCr) based alloys, in addition to stainless steels, titanium, and titanium-based, are used in Food and Drug Administration (FDA)-approved medical devices. The high chromium content (26-30 wt%) imparts superior oxidation or corrosion resistance in elevated temperature conditions and dynamic environments. For example, this CoCr alloy is biocompatible in a physiological environment. Despite their good strength and excellent wear resistance for load-bearing implants, the wear debris induces oxidation of metallic particles like Co2+ and Cr3+ that are known to be cancerous. A secondary problem is the possibility of infection at the implant site, which usually occurs after implantation, or the formation of a biofilm tends to occur before tissue can interact with the material’s surface.
Additive manufacturing (AM), such as directed energy deposition (DED), was used to fabricate CoCr composites to improve the wear performance and provide an inherent antibacterial property. To reduce the accumulation of wear debris and metal ion release, hydroxyapatite (Ca10(PO4)6(OH)2 or HA), a main constituent of natural bone, was added with CoCrMo to form an in situ tribofilm during wear that provides a physical barrier between the rubbing surfaces. Simultaneously, copper was added to demonstrate the inherent antibacterial resistance and ensure confidence in avoiding infection. Four compositions were manufactured via DED: CoCrMo (CCM), CoCrMo – 3 wt% Cu (3Cu), CoCrMo – 3 wt% Cu – 1 wt% HA (1HA), and CoCrMo – 3 wt% Cu – 2 wt% HA (2HA).
The results for wear performance of the CCM composites containing hydroxyapatite showed a reduction in wear rate and friction coefficient and the ability to form an in situ tribo-film. Bactericidal activity was demonstrated from the copper and HA composites against bacteria Pseudomonas aeruginosa. The results give confidence that metal-AM modified CoCrMo can reduce the wear rate of the alloy and metal-ion release of Co2+ and Cr3+ by adding HA to form a
non-conducting protective layer, and infection can be controlled by adding copper. This research addresses the wear and corrosion-related problems associated with biomaterials for load-bearing applications using additive manufacturing.
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Details
- Title
- IMPROVING WEAR PERFORMANCE AND BACTERICIDAL ACTIVITY OF Cu AND HYDROXYAPATITE REINFORCED CoCrMo IMPLANTS
- Creators
- Cassandra Lissett Orozco
- Contributors
- Amit Bandyopadhyay (Chair)Susmita Bose (Committee Member)Kaiyan Qiu (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Mechanical and Materials Engineering
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 77
- Identifiers
- 99901152337501842
- Language
- English
- Resource Type
- Thesis