SiC-BN Ceramic Matrix Composites by In-situ Reaction
YANG Zhi-hua, JIA De-chang, ZHOU Yu, SONG Cheng-bin, SHI Peng-yuan (School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China)
SiC-BN ceramic matrix composites have been designed and fabricated via in-situ synthetic reaction. By theoretical calculations and experimental methods, the anticipated in-situ reaction was proved enabled at relatively low sintering temperature of 1700℃. In the composites, fine SiC and BN particles disperse homogeneously, and nano-sized SiC can be found where the additives are more. For the SiC-BN composites, flexural strength and fracture toughness reached the maximum values when the content of BN is 20vol%, 311MPa and 4.5 MPa·m 1/2 , respectively. Moreover the elastic modulus and the hardness of the composites decreased with the increasing of content of BN, which are 40.8GPa and 0.55GPa for the B60 specimen. Intragranular fracture can be found in the B0 specimen, while intergranular fracture can be found in the composites containing BN.