Microstructure of ZrB2–SiC Composite Fabricated by Spark Plasma Sintering
ZrB2-SiC composite is a promising candidate for ultra-high temperature ceramics, which is difficult to be sintered due to strong covalent bonding of ZrB2 and SiC. ZrB2-30Vol.%SiC composite was prepared by spark plasma sintering technique (SPS) at the sintering temperature of 1850°C, sintering pressure of 50MPa, heating rate of 200°C/min and holding time of 3 minutes. The phase components and microstructure were examined by X-ray diffraction, scanning electron microscopy and transmitting electron microscopy. The results show that the product is composed of ZrB2 phase, SiC phase and ZrO2 phase. A rationalization for the presence of ZrO2 phase is based on the impurity of raw material and oxidation of ZrB2 during SPS. The consolidated product is very dense and no apparent pores exist in the microstructure. ZrO2 phase with irregular shape is found among some particles as a binder phase. It is shown that the presence of ZrO2 phase may be beneficial to the densification of ZrB2-SiC composite.
Wei Pan and Jianghong Gong
J. L. Cao et al., "Microstructure of ZrB2–SiC Composite Fabricated by Spark Plasma Sintering", Key Engineering Materials, Vols. 368-372, pp. 1743-1745, 2008