Abstract

Uneven contact promotes premature wear on the mechanical hip replacement. Tribological assessment of even-contact tribopair has previously focused on wear characteristics. On the contrary, uneven contact tribology behavior, which is sometimes overlooked in tribology, is critical to consider when evaluating and designing synovial joints of biomedical implants. Using a ball-on-disk tribometer, this study incorporates knowledge of uneven contact tribology characterization between tribopair of ZTA disc and counter bodies such as diamond tip and cubic ZrO2 ball. The dense bodies were made by uniaxially pressing and sintered the green pellets at 1600oC for 6 hours. A specially designed sample holder of a pin-on-disc tribometer investigated the dry wear and frictional behaviour of a biocompatible ZTA composite system. The diamond indenter damaged the ZTA sample surface, causing significant material loss. Similarly, a ZTA sample also came into touch with a ZrO2 ball, causing minor surface damage. For a diamond tool, the coefficient of friction was 0.05, while for a ZrO2 ball, it was 0.56. The wear depth increases when using a diamond tool on a ZTA surface. The linear bearing ratio revealed a worn surface pattern. Surface cracks, grain pullout, third body debris, and ploughing were fundamental wear mechanisms on the uneven contact ZTA vs. counter bodies’ tribopairs.