EFFECT OF MICROSTRUCTURE ON THE WEAR TRANSITION OF ZIRCONIA-TOUGHENED ALUMINA

The mechanical properties of alumina ceramics can be improved by the addition of pure or partially stabilized zirconia particles. In the present study, the wear characteristics of zirconia-toughened alumina (ZTA) composites under a non-reactive fluid (paraffin oil) lubricated condition were investigated. The wear transition load (i.e. the load at which a rapid increase in wear occurs) increased with increasing zirconia content up to 20 vol.%. The transition from mild to fracture-controlled wear of ZTA depends on the material properties (e.g. hardness, elastic modules), the contact conditions (e.g. hertzian stress, coefficients of friction) and the microstructure of the material. The effect of the microstructure on wear was demonstrated and a Hall-Petch-type relationship between the microfracture stresses and the grain size was found. The effect of the grain size distribution on the wear transition load was also shown.