Effect of cooling rates on mechanical properties of alumina-toughened zirconia composites

Abstract

Alumina-toughened zirconia (ATZ) composites are attractive structural ceramics that are widely used in many industrial components owing to their remarkable mechanical properties, such as high strength, hardness, toughness, and wear resistance. These properties are strongly affected by the ZrO2 phase transformation from the tetragonal to the monoclinic phase, which can be induced by external stress. Controlling the microstructure and residual stress generated during the sintering process can control this phase transformation. In this study, to enhance the mechanical properties of ATZ composites, we conducted a systematic investigation on the effect of different cooling rates after sintering ATZ composites with 10 vol% Al2O3 at 1550 °C on the microstructural evolution and residual stress of the matrix phase. The mechanical properties were strongly dependent on the residual stress generated during the cooling process after sintering at elevated temperatures. The ATZ composite with a −1 °C/min cooling rate showed the maximum fracture toughness of 9.5 MPa √ m and the lowest tensile residual stress.