Effect of Nano-ZrO2 on Microstructure and Thermal Shock Behaviour of Al2O3/SiC Composite Ceramics Used in Solar Thermal Power

The Al2O3-ZrO2(3Y)-SiC composite ceramics used in solar thermal power were prepared by micrometric Al2O3, nano-ZrO2 and SiC powders under the condition of pressureless sintering. The bulk density and bending strength of samples with 10vol% nano-ZrO2 sintered at 1480 degrees C were 3.222 g/cm(3) and 160.4 MPa, respectively. The bending strength of samples after 7 times thermal shock tests (quenching from 1000 degrees C to 25 degrees C in air medium) is 132.0 MPa, loss rate of bending strength is only 17%. The effect of nano-ZrO2 content on the microstructure and performance of Al2O3-ZrO2(3Y)-SiC composite ceramic was investigated. The experimental results show that the bending strength of samples with above 10vol% nano-ZrO2 content has decreased, because the volume expansion resulting from t-ZrO2 to m-ZrO2 phase transformation is excessive; Adding proper nano-ZrO2 would be contributed to improve the thermal shock resistance of the composite ceramics. The Al2O3-ZrO2(3Y)-SiC composite ceramic has promising potential application in solar thermal power.