Single asperity nanoscale wear of carbides and matrix of wrought high carbon CoCrMo alloy

High carbon CoCrMo alloy has been widely used in orthopedic implants. Carbides improve the strength of the material and influence wear resistance. An atomic force microscopy (AFM)-based single asperity tribology method was developed to investigate the wear performance of individual carbides and base metal matrix of high carbon CoCrMo alloy. Sub-nano to nanoscale wear on single carbides was performed and quantified. Nanowear behavior of two types (Cr-rich and Mo-Rich) of carbides was stress-dependent (from 7.8 GPa to 9.8 GPa) and influenced by chemical composition. The lower wear depth of both Cr-rich and Mo-rich carbide compared to the matrix alloy shows higher wear resistance compared to metal matrix. Cr-rich carbides exhibit significantly smaller wear depth (p < 0.05) compared to Mo-rich carbides after nanowear at the same contact stress (9.8 GPa). The entire region of Cr-rich carbide shows high wear resistance without fracture after nanowear at 14.7 GPa. The AFM-based nanowear methods used are able to detect sub-nanometer wear depths on worn regions as small as 0.2 mu m and provide abilities to study local nanometer wear processes in complex alloy systems.

Automated summary

An AFM-based single asperity tribology method was used to investigate the wear performance of carbides and base metal matrix in high carbon CoCrMo alloy. The wear behavior of the two types of carbides was stress-dependent and influenced by chemical composition. Cr-rich carbides exhibited higher wear resistance compared to Mo-rich carbides.