Effect of hydrothermal treatment on tribological properties of alumina and zirconia based bioceramics

Four types of ceramic composites; ceria stabilized zirconia (CSZ), yttria stabilized zirconia (YSZ), ceria stabilized zirconia toughened alumina (CSZ-TA) and yttria stabilized zirconia toughened alumina (YSZ-TA) were developed through powder metallurgy route using conventional pressure less resistance heating. Hydrothermal treatment was carried out to estimate the ageing stability of the developed materials. Fretting wear using ball on flat geometry were carried out before and after hydrothermal treatment to understand the effect of hydrothermal treatment on wear properties of developed materials. Variation of wear properties like wear depth, wear volume and coefficient of friction with duration of hydrothermal treatment was correlated with the microstructure and phase developed before and after hydrothermal treatment. It was found that presence of ceria decreases wear damage after hydrothermal treatment. For CSZ, wear volume decreased to 800×105 μm3 from 1488×105 μm3 while for YSZ it increased to 220×105 μm3 from 28×105 μm3 at 20 N load. Similar trend was found in CSZ-TA and YSZ-TA specimens also. It was understood that during hydrothermal treatment, a part of tetragonal phase of CSZ transforms to orthorhombic zirconia which in turn improves the wear properties.