  This paper considers the degradation of alumina and zirconia toughened
alumina vs. alumina for hip implants. The materials are as assumed to be load
bearing surfaces subjected to shocks in wet conditions. The load is a peak of
force; 9 kN was applied over 15 ms at 2 Hz for 800,000 cycles. The volumetric
wear and roughness are lower for ZTA than for alumina. The long ZTA ageing did
not seem to have a direct influence on the roughness. The ageing increased the
wear volumes of ZTA and it was found to have a higher wear resistance compared
to alumina.

Medical Physics