Comparison of nano-f`retting and nano-scratch tests on biomedical materials

Nano-scratch and nano-fretting tests were performed on highly polished biomedical grade Ti6Al4V, 316L stainless steel and CoCr alloy samples using a 3.7 μm sphero-conical diamond indenter in a commercial nanomechanical test system (NanoTest). Over a wide range of experimental conditions the CoCr alloy showed significantly better wear resistance. The scratch recovery and mean contact pressure for plastic deformation in a low pass repetitive scratch test both correlated with mechanical properties determined from nanoindentation testing. Decreases in friction during the initial wear cycles of this low-cycle test were consistent a reduction in ploughing. In the extended nano-fretting tests Ti6Al4V and 316L stainless steel showed delamination wear.