Effect of zirconia addition on the oxidation resistance of Ni-toughened Al2O3

The incorporation of equal amount of Ni and ZrO2 particles can significantly enhance the toughness of Al2O3. In the present study, the oxidation resistance of Al2O3/ZrO2/Ni composites at 1200 °C for up to 400 h is evaluated. The presence of ZrO2 particles accelerates the oxidation of Ni particles in the Al2O3 matrix. Furthermore, the oxidation rate constant of the composites increases significantly when the ZrO2 addition is higher than 10 vol.%, the threshold at which that ZrO2 inclusions form continuous networks. The effect of the polymorphic form of ZrO2 on the oxidation resistance is also evaluated. The oxidation resistance of Al2O3/m-ZrO2/Ni composites is slightly better than that of Al2O3/t-ZrO2/Ni composites.