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

Traditional powder metallurgy was employed to prepare alumina–zirconia (Al ₂ O ₃ –ZrO ₂ ) and alumina–zirconia–aluminium (Al ₂ O ₃ –ZrO ₂ –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 Al ₂ O ₃ –ZrO ₂ appears to be 430.7 MPa when sintered at 1650°C, and Al ₂ O ₃ –ZrO ₂ –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 ZrO ₂ (m‐ZrO ₂ ) increases. The addition of Al powder improves the dispersion of ZrO ₂ , reduces the porosity of zirconia toughened alumina ceramics, and improves the bending strength. Al powder increases the content of the intragranular ZrO ₂ , restrains the t–m phase transformation, results in the decreases of the relative amount of m‐ZrO ₂ in ZrO ₂ ( X _m ). Adding Al powder during ball milling is a simple method to increase the content of intragranular ZrO ₂ in Al ₂ O ₃ –ZrO ₂ ceramics.