Effect of micron aluminium powder on mechanical properties and microstructural in zirconia toughened alumina ceramics

Traditional powder metallurgy was employed to prepare alumina–zirconia (Al2O3–ZrO2) and alumina–zirconia–aluminium (Al2O3–ZrO2–Al) ceramics. It was found that as the sintering temperature increases, the flexural strength of both ceramics increases first and then decreases. The maximum flexural strength of Al2O3–ZrO2 appears to be 430.7 MPa when sintered at 1650°C, and Al2O3–ZrO2–Al appears to be 448.8 MPa when sintered at 1600°C. As the sintering temperature increases, the grain size of each phase grows up, the porosity increases, the content of intragranular phase and monoclinic ZrO2 (m-ZrO2) increases. The addition of Al powder improves the dispersion of ZrO2, reduces the porosity of zirconia toughened alumina ceramics, and improves the bending strength. Al powder increases the content of the intragranular ZrO2, restrains the t–m phase transformation, results in the decreases of the relative amount of m-ZrO2 in ZrO2 (Xm). Adding Al powder during ball milling is a simple method to increase the content of intragranular ZrO2 in Al2O3–ZrO2 ceramics.