Effect of sintering processes on microstructure and properties of Al₂O₃-ZrO₂ ceramics

Al₂O₃-ZrO₂ ceramics with 10,15 and 20%ZrO₂ were prepared by non-pressure sintering at 1650,1700 and (1650-1700)°C. The microstructure of the specimens was examined by XRD,SEM and EPMA techniques. Density, hardness and dynamic fracture energy were measured. It was shown that with increasing sintering temperacure and ZrO₂ content the amount of t-ZrO₂ decreases. For 1650°C sintered specimens the density is lower and the toughness increases with increasing t-ZrO₂ content by the mechanism of transformation toughening. For 1700 and (1650-1700)°C sintered specimens the density is higher and the tZrO₂ content is lower. In this case the increase of toughness is obtained by the mechanism of microcracking.