GUO Yawei 1,2, CHAI Jianlong 1,2, ZHU Yabin 1, WEI Kongfang 1, LI Shufen 1,2, SHEN Tielong 1, YAO Cunfeng 1, CUI Minghuan 1, WANG Zhiguang 1
(1. Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, Gansu, China; 2. University of Chinese Academy of Sciences, Beijing 100049, China)
Abstract: The α-Al2O3, ZrO2 and MgO powders were mixed by ball milling firstly, and then the Al2O3/ZrO2/MgAl2O4 (AZM) composite ceramics were prepared by spark plasma sintering (SPS). The effects of MgAl2O4 addition on microstructure, mechanical, thermal and electric properties of AZM composite ceramics were investigated. X-ray diffraction analysis indicated that the phases of the composite ceramics consisted of α-Al2O3, t-ZrO2 and MgAl2O4, without any other impurities. SEM cross-sectional images showed that the fracture mode of the AZM composite ceramics was a combination of intergranular fracture and transgranular fracture. With the increase of the MgAl2O4 content, the fracture toughness of composite ceramics increased from 12 MPa·m1/2(0v.%) to 17.48 MPa·m1/2(20v.%) at first and then decreased gradually to 14.46 MPa·m1/2(40v.%), while the vickers hardness decreased gradually from 21 GPa(0 v.%) to 15.3 GPa(40v.%); meanwhile, the thermal conductivity decreased gradually from 9.3 W/(m·K) (20v.%) to 7.6 W/(m·K) (35v.%) at room temperature. However, MgAl2O4 has little impact on the coefficient of thermal expansion. Additionally, the electrical resistance of AZM3O and ZTA composite ceramics were 6.6 × 108 Ω·cm(30v.%) and 3.3 × 109 Ω·cm respectively at 200 ℃.
Key words: MgAl2O3; Al2O3/ZrO2; SPS; microstructure; physical properties