Low amplitude oscillatory wear in yttria-stabilised zirconia

Studies have been made of the oscillatory wear caused by zirconia rods moving on zirconia bars with an amplitude of 5mm and at a frequency of 15Hz. Both sets of components were manufactured from 2.5mol% yttria-stabilised zirconia (2.5Y-TZP) sintered at 1400 C. Various experimental conditions were used. Bars were tested as-received in air, water and Ringer's solution, an artificial body fluid. The effects of ageing in autoclave conditions at 120 C on the amount of wear was also studied. Wear rates in water at room temperature were very low, slightly higher values were observed in Ringer's solution at 37.8 C and the greatest wear occurred for samples aged for the longest time at 120 C and tested in air. Correlations between ageing-induced phase changes and the amounts of wear were established and debris from a wear scar on an aged bar was found to be very high in monoclinic phase whereas the surface showed a much depleted monoclinic content. There was a strong dependence of wear rates on fracture toughness, the latter values being varied as a result of ageing. (orig.)