Mechanical properties and microstructure of ZrO2–TiN–Al2O3 composite ceramics

20 wt% TiN/3Y-TZP mixed with an amount of less than 15 wt% Al2O3 particles has been fabricated by hot-pressing techniques, and the mechanical properties and microstructure were investigated. There is a good chemical compatibility among ZrO2, TiN and Al2O3 and the addition of 5 wt% Al2O3 can improve the densification of composites. Al2O3 particles have little effect on improving flexural strength but have a distinct effect on toughening for 20 wt% TiN/3Y-TZP, which may be due to the residual stresses and microcracks resulting from the mismatch between the expansion coefficients of Al2O3 and ZrO2. An amount of 5 wt% Al2O3 in 20 wt% TiN/3Y-TZP can improve the bonding strength among grains and change the fracture pattern from intergranular to transgranular fracture.