Processing of homogeneous zirconia-toughened alumina ceramics with high dry-sliding wear resistance

The preparation of dense homogeneous zirconia-toughened alumina (ZTA) with high dry-sliding wear resistance is described. These ZTA ceramics are obtained by sintering green compacts, made by colloidal filtration of well-defined ZrO2-Al2O3 particle suspensions, for 2 h at 1400°C. The optimum solid and stabilizer concentrations for the filtration process were determined. The sintered ZTA microstructure consists of a homogeneous distribution of zirconia grains in an alumina matrix with grain sizes of 0.2 and 0.5 µm, respectively. In pin-on-disk tribological measurements at relatively high initial contact pressures (1130 MPa) and sliding speeds (0.5 m/s) a very low specific wear rate (about 5 × 10-8 mm3/(N·m)) and a coefficient of friction of 0.45–0.55 were found. It is shown that, in this case, wear is dominated by abrasion and polishing.