Cobalt-based orthopaedic alloys: Relationship between forming route, microstructure and tribological performance

Patel, Bhairav, Favaro, Gregory, Inam, Fawad, Reece, Michael, Angadji, Arash, Bonfield, William, Huang, Jie and Edirisinghe, Mohan (2012) Cobalt-based orthopaedic alloys: Relationship between forming route, microstructure and tribological performance. Materials Science and Engineering: C, 32 (5). pp. 1222-1229. ISSN 0928-4931

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Official URL: http://dx.doi.org/10.1016/j.msec.2012.03.012

Abstract

The average longevity of hip replacement devices is approximately 10–15 years, which generally depends on many factors. But for younger generation patients this would mean that revisions may be required at some stage in order to maintain functional activity. Therefore, research is required to increase the longevity to around 25–30 years; a target that was initially set by John Charnley. The main issues related to metal-on-metal (MoM) hip replacement devices are the high wear rates when malpositioned and the release of metallic ions into the blood stream and surrounding tissues. Work is required to reduce the wear rates and limit the amount of metallic ions being leached out of the current MoM materials, to be able to produce an ideal hip replacement material. The most commonly used MoM material is the cobalt-based alloys, more specifically ASTM F75, due to their excellent wear and corrosion resistance. They are either fabricated using the cast or wrought method, however powder processing of these alloys has been shown to improve the properties. One powder processing technique used is spark plasma sintering, which utilises electric current Joule heating to produce high heating rates to sinter powders to form an alloy. Two conventionally manufactured alloys (ASTM F75 and ASTM F1537) and a spark plasma sintered (SPS) alloy were evaluated for their microstructure, hardness, tribological performance and the release of metallic content. The SPS alloy with oxides and not carbides in its microstructure had the higher hardness, which resulted in the lowest wear and friction coefficient, with lower amounts of chromium and molybdenum detected from the wear debris compared to the ASTM F75 and ASTM F1537. In addition the wear debris size and size distribution of the SPS alloy generated were considerably small, indicating a material that exhibits excellent performance and more favourable compared to the current conventional cobalt based alloys used in orthopaedics.

Item Type: Article
Subjects: F200 Materials Science
H300 Mechanical Engineering
J200 Metallurgy
J700 Industrial Biotechnology
Department: Faculties > Engineering and Environment > Mechanical and Construction Engineering
Depositing User: Fawad Inam
Date Deposited: 24 May 2013 13:54
Last Modified: 10 Aug 2015 11:16
URI: http://nrl.northumbria.ac.uk/id/eprint/12647

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