CHAI Jianlong 1,2, GUO Yawei 1,2, ZHU Yabin 1, LI Shufeng 1,2, SHEN Tielong 1, YAO Cunfeng 1, CUI Minghuan 1, WANG Zhiguang 1
(1. Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730070, Gansu, China; 2. University of Chinese Academy of Sciences, Beijing 100049, China)
Abstract: Oxide/carbide composite ceramics were prepared by spark plasma sintering (SPS) using α-Al2O3, ZrO2 and β-SiC powders as raw materials. The effects of SiC doping on the microstructure, mechanical and thermal properties of zirconia-toughened alumina (ZTA)- and alumina-toughened zirconia (ATZ)- based composites were investigated. The XRD patterns show that the components in the sample are α-Al2O3, ZrO2 and β-SiC, and no other impurity phases exist. As the SiC content increases, the fracture toughness of ZTA-SiC composite ceramics increases from 4.3 to 7.6 MPa·m1/2 at first and then decreases to 6.6 MPa·m1/2, while the fracture toughness of ATZ-SiC composite ceramics shows no obvious changes, which is constant at about 11 MPa·m1/2. SEM images show that the high toughness of the samples is attributed to the transgranular fracture, which increases at first and then decreases as the SiC content increases. At the same temperature, the thermal conductivity of the composite ceramics increases with the content of SiC. The thermal conductivities of ZTA-SiC and ATZ-SiC composite ceramics increasefrom 4.31 and 5.39 W/m·K to 5.50 and 8.10 W/m·K, respectively, when the temperature goes up to 1200 °C.
Key words: SiC; ZTA/ATZ composite ceramics; fracture toughness; bending strength; thermal conductivity