Preparation and thermal shock resistance investigation of ZTA-La2O3 composite ceramics for porous medium combustion materials

Abstract

Zirconia-alumina composite ceramics are the preferred materials for high temperature and thermal shock applications because of their excellent mechanical properties. In this paper, La2O3 doped zirconia-alumina composite ceramics were prepared by using fused zirconia corundum and ZrO2 as starting materials. The effects of La2O3 on the phase composition, microstructure and properties of the composite ceramics were investigated by XRD and SEM. The results show that La2O3 can reduce the sintering temperature and improve the bending strength of the samples. The bending strength and fracture toughness of the composite ceramics with 1.5 wt% La2O3 sintered at 1480 °C are 299.17 MPa and 5.61 MPa m1/2, respectively. The strength loss rate of the sample after 30 thermal shocks (room temperature ∼ 1000 °C) is 2.67%, SEM shows that the grain sizes of alumina and zirconia in the sintered sample were about 5 μm and 2 μm, respectively. After 30 thermal shocks, the phase composition and microstructure of the sample have no significant change, indicating good thermal shock resistance of the composite ceramics. The excellent thermal shock resistance ensures porous medium combustion materials has a long service life.