XIONG Shunjin ¹, HUANG Rongxia ¹, LIU Rongzheng ², DU Zuchao ¹, WU JianBo ¹, FENG Jin ¹

(1. School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, Guangdong, China;2. Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China)

Abstract: Al₂O₃ and ZrO₂ were employed as sintering aids for SiC ceramic composites. Spark plasma sintering (SPS) technology was used to prepare high-density SiC ceramics at 1800 ℃ and 30 MPa. The effects of silicon carbide whiskers (SiCw) on microstructure, phase composition and mechanical properties of the SiC ceramics were studied. It was found that the samples mainly consisted of β-SiC, t-ZrO₂ and m-ZrO₂. The addition of SiCw hindered the grain growth of the SiC ceramics. With optimal concentration of SiCw, the mechanical properties of the SiC ceramics were significantly improved. Specifically, as the content of SiCw was 20 wt.%, the fracture toughness and flexural strength reached 5.35 MPa·m^1/2 and 650 MPa, respectively. The toughening mechanisms included crack deflection and crack bridging, due to the synergistic effect of SiCw and ZrO₂, thereby enhancing the strength and toughness of the composite samples.

Key words: SiCw; ZrO₂; fracture toughness; flexural strength