China's Refractories

Abstract: Effects of B4C additions (0, 0.2%, 0.4%, and 0.6%) on cold physical properties and hot modulus of rupture of Al2O3–SiC–Si3N4 castables for iron trough were investigated. The phase composition and microstructure were analyzed by XRD and SEM. The results show that bulk density, cold strength, and hot modulus of rupture of the castables first increase and then decrease while apparent porosity first drops and then increases with B4C addition increasing. The optimum addition of B4C is 0.4%. B4C mainly contributes to sintering and antioxidation. Compared with the specimens without B4C, the specimens with B4C have more fibrous O’-SiAlON with larger length diameter ratio. The growth mechanism of O’-SiAlON crystals is deduced to gas-solid mechanism.

Key words: AluminaCsilicon carbideCsilicon nitride, Castables for iron tough, Boron carbide, O- SiAlON, Antioxidation