Wear Behavior of Biomedical Co-Cr-Mo F75 Alloys in Simulated Body Fluid

Pin-on-disk wear test using Co-Cr-Mo-C-N-Si-Mn cast alloy pins and alumina disks was conducted in Kokubo and 1mass% lactic acid solutions. The precipitates in the as-cast alloys were M23X6 type, π-phase and M2X type. After wear test, it was found that the ratio of the amount of eluted ions in 1mass% lactic acid solution corresponded to the chemical composition of alloys. The detached of M2X type precipitate was observed in as-cast alloy after wear test in 1mass% lactic acid solution. Meanwhile, the elution of metallic ions in Kokubo solution was much less that in 1mass% lactic acid solution. Concentration of Cr was extremely low in Kokubo solution. The formation of CrOOH during test in Kokubo solution might suppress the concentration of Cr.