Ns. Vandamme et al., Carbide surface coating of Co-Cr-Mo implant alloys by a microwave plasma-assisted reaction, J MATER SCI, 34(14), 1999, pp. 3525-3531
A technique to grow a hard carbide surface coating on Co-Cr-Mo implant allo
ys used in artificial joints was developed. The carbide surface coating was
applied to as-cast and forged Co-Cr-Mo alloys to improve their wear proper
ties. The surface carbide layers were produced by reactions between the all
oy surface and a methane-hydrogen mixed gas by a microwave plasma-assisted
surface reaction. The new carbide layers showed "brain coral-like" surface
morphology and appear to consist of mixed phases including Cr3C2, Cr2C, Cr7
C3, Cr23C6, and Co2C. The Vickers microhardness of thin carbide coatings (s
imilar to 3 mu m thick) was about HV 1100 regardless of the test location.
The Vickers microhardness of thick carbide coatings (similar to 10 mu m thi
ck) showed a wide range of hardnesses from HV 1000 to HV 2100. Co-depositio
n of soot and diamond films occured on a small area of the forged alloy sub
strates and diamond particles were sparsely dispersed on as-cast alloy subs
trates. The carbide surface layer has the potential to increase the wear re
sistance of the Co-Cr-Mo alloy as a wear resistant coating. (C) 1999 Kluwer
Academic Publishers.