CoCrMo alloy for orthopedic implant application enhanced corrosion and tribocorrosion properties by nitrogen ion implantation

CoCrMo alloy corrosion and tribocorrosion properties are crucial for orthopedic implant application. These properties have been enhanced by implanting nitrogen ions with 100 keV energy. The corrosion current density of the implanted alloy is reduced by an order of magnitude, compared with the original alloy without implantation. In the tribocorrosion tests, the potential of the implanted alloy remain almost unchanged at around 0.05 V versus Ag/AgCl, while the potential of the original alloy without implantation changes from −0.4 to −0.6 and then to about −0.5 V versus Ag/AgCl, showing typical tribocorrosion behavior. Tribocorrosion tests also show that the 4 × 1017 N+/cm2 implantation reduces the friction coefficient from 0.35 to 0.15. Various characterization results indicate that the implantation induces a novel composite microstructure of the nanocrystalline CrN embedded inside amorphous CoCrMo matrix in the implanted layer, which enhances hardness, corrosion and tribocorrosion properties.