New insights into wear of Ti6Al4V by ultra-high molecular weight polyethylene under water lubricated conditions

Laboratory studies indicate that sliding Ti6Al4V against soft ultra-high mo lecular weight polyethylene (UHMWPE.) pins produces severe damage to the ti tanium and the lubricant (water) changes colour suggesting chemical change. Blackening of periprosthetic tissues associated with titanium wear debris was also observed in clinical investigations. To increase scientific unders tanding of the mechanism involved, systematic characterisation work has bee n conducted employing grow discharge spectrometry (composition), scanning e lectron microscopy (wear morphology) and cross-sectional transmission elect ron microscopy (phase identification). Experimental results show that hydro gen may play an important role in promoting the formation of abrasive parti cles in the Ti6Al4V/UHMWPE tribosystem under water lubricated conditions. T he observed abnormal wear of Ti6Al4V by soft UHMWPE can be to a large exten t attributed to hydrogen evolution and formation of titanium hydride. Based on experimental results and discussion, a hydrogen-assisted wear mechanism is proposed. (C) 2001 Elsevier Science B.V. All rights reserved.