Abstract
This study focuses on the surface modification of a medical grade Co-Cr alloy via combining cold spray and thermal oxidation processes. After deposition of a Ti96-Al4 (wt.%) coating, samples were oxidized at 600 °C for 60 h in air. Oxidation transformed the coating into a dual-layered structure comprising an outer oxide layer (mainly rutile) with a diffusion layer (mainly oxygen enriched titanium and Ti-Al intermetallics) beneath it. Formation of new phases made the diffusion layer brittle and prone to fracture during pull out tests. Scratch and Rockwell-C tests confirmed good adhesion between the oxide and underlying diffusion layers, having average hardness as 1297 HV and 387 HV, respectively. The dual-layer coating exhibited excellent wear performance in a 0.9 wt.% NaCl solution against sliding action of alumina ball as compared to Co-Cr substrate, especially at contact pressures < 1200 MPa, while the maximum in vivo contact pressure is < 15 MPa for load-bearing orthopedic implants. Furthermore, the release of the aluminum from the dual-layer coating into 0.9 wt.% NaCl solution is lower than the permissible limit stated by the International Agency for Research on Cancer.
Original language | English |
---|---|
Pages (from-to) | 1414-1427 |
Number of pages | 14 |
Journal | Journal of Thermal Spray Technology |
Volume | 27 |
Issue number | 8 |
DOIs | |
Publication status | Published - 1 Dec 2018 |
Bibliographical note
Publisher Copyright:© 2018, ASM International.
Keywords
- Co-Cr alloy
- coating
- cold spray
- thermal oxidation
- titanium
- wear