Effect of Nano-Al2O3 Particles Addition on Thermal Shock Resistance of ZTA/Cordierite Composites

Abstract

ZTA/cordierite composites were prepared using ZrO2, Micro-Al2O3/Nano-Al2O3 and cordierite as raw materials by pressureless sintering. The influence of Nano-Al2O3 particles content on phase composition, microstructure and thermal shock resistance of ZTA/cordierite were investigated. The results show that m-ZrO2, t-ZrO2 and Al2O3 existed in the matrix and t-ZrO2 content increased with the increase of Nano-Al2O3 powders content. By adding Nano-Al2O3 powders and ultrasonic dispersion, which can refine grain and promote sintering, the grain size is uniform, the porosity is less and some grains were pulled out, the fracture mode changes from intergranular fracture to intergranular fracture and transgranular fracture. The thermal shock test was carried out at 300°C-1000°C, the critical thermal shock temperature of ZTA ceramic without adding cordierite and Nano-Al2O3 particles is 800°C and the residual strength retention rate of the material is only 32.4%. But by adding Nano-Al2O3 powers and ultrasonic dispersion 30 min,the residual strength retention rate, relative density, flexural strength and fracture toughness of ZTA/cordierite sintered at 1550°C for 4 h increased greatly and were up to 73.6%, 97.2%, 436 MPa and 4.6 MPa.m1/2, respectively.