Microstructure and mechanical properties of ZTA fabricated by liquid phase sintering

Zirconia-toughened alumina (ZTA) ceramics with ZrO2 volume fraction from 0 to 50 vol.% were pressurelessly prepared with the addition of 1 wt.% TiO2–1 wt.% MnO2 and 2 wt.% CaO–Al2O3–SiO2 (CAS) as sintering aids. The influence of ZrO2 content and sintering temperature on microstructure and mechanical properties of the composites were investigated. All samples can be fully densified at as low as 1400 °C. For pure Al2O3 sample, platelike grains appeared. With the addition of ZrO2, platelike grains of Al2O3 conversed to equiaxed grains and their sizes decreased gradually. Mechanical properties increased with ZrO2 content. When 50 vol.% was added, strength and toughness of composite reached 619±36 MPa and 7.02±0.06 MPam1/2, respectively. The toughening mechanism was phase transformation based on analyzing the transformable ZrO2 content.