Influence of Adding TiB₂ on Structure and Mechanical Properties of SiC-Based Composite Ceramics

SiC-TiB₂ composite ceramics were prepared by a spark plasma sintering technique using Y₃Al₅O₁₂ (YAG) as a sintering additive. The influences of SPS sintering temperature and addition of TiB₂ on the microstructure, especially the microstructure of intergranular phases, as well as the mechanical properties of the ceramics were investigated by X-ray diffraction, scanning and transmission electron microscopy, and energy disperse spectroscopy, respectively. The results show that the addition of TiB₂ has a negative effect on the densification, causes the intergranular phases transform from crystalline phase to amorphous phase, and increases the bonding strength between grains, thus improving the mechanical properties. The maximum flexural strength and the maximum fracture toughness of SiC-TiB₂ ceramic are 753 MPa sintered at 1 750℃ and 8.84 MPa·m^½ sintered at 1 700℃, respectively.