Characteristics of hydrothermal stability and machinability of t-ZrO2/Al2O3 composites as a femoral head for total hip replacements

The femoral heads for hip replacements are fabricated by adding Al2O3 into t-ZrO2 solid solutions doped with Y2O3, Nb2O5 and CeO2 ((Y,Nb,Ce)-TZP/Al2O3) to investigate the hydrothermal stability and machinability. After autoclaving, no m-ZrO2 is observed for the (Y,Nb,Ce)-TZP/20 vol.% Al2O3 (Al20Ce) composite when the composite is sintered at less than 1500 °C. The (Y,Nb,Ce)-TZP/80 vol.% Al2O3 (Al80Ce) composite maintains the phase stability up to 1580 °C. Contrary to 3Y-TZP and Al20Ce, Al80Ce show a steady flexural strength increase with increasing the sintering temperature. Characteristics of green compact machinability are evaluated as a function of moisture content for the granulated particle and found that the roughness and sphericity of Al20Ce green compacts are optimized at the granule's moisture content of 0.3 wt.%. The surface roughness (sphericity) of the femoral heads made with 3Y-TZP, Al20Ce and Al80Ce is 0.01 (0.439), 0.02 (0.644) and 0.06 μm (2.923 μm), respectively.