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- Title
Improved adhesion of ultra-hard carbon films on cobalt-chromium orthopaedic implant alloy.
- Authors
Catledge, Shane A.; Vaid, Rishi; Diggins, Patrick; Weimer, Jeffrey J.; Koopman, Mark; Vohra, Yogesh K.
- Abstract
While interfacial graphite formation and subsequent poor film adhesion is commonly reported for chemical vapor deposited hard carbon films on cobalt-based materials, we find the presence of O in the feedgas mixture to be useful in achieving adhesion on a CoCrMo alloy. Nucleation studies of surface structure before formation of fully coalesced hard carbon films reveal that O feedgas helps mask the catalytic effect of cobalt with carbon through early formation of chromium oxides and carbides. The chromium oxides, in particular, act as a diffusion barrier to cobalt, minimizing its migration to the surface where it would otherwise interact deleteriously with carbon to form graphite. When O is not used, graphitic soot forms and films delaminate readily upon cooling to room temperature. Continuous 1 μm-thick nanostructured carbon films grown with O remain adhered with measured hardness of 60 GPa and show stable, non-catastrophic circumferential micro-cracks near the edges of indent craters made using Rockwell indentation.
- Subjects
COBALT-chromium-nickel alloys; ELECTROSTATIC adhesion; ORTHOPEDICS; DENTAL bonding; PROPERTIES of matter; TRANSITION metals
- Publication
Journal of Materials Science: Materials in Medicine, 2011, Vol 22, Issue 2, p307
- ISSN
0957-4530
- Publication type
Article
- DOI
10.1007/s10856-010-4207-1