LAUSR

Abstract The ultra-low cement bonded Al2O3-SiC-C castables were prepared with the introduction of a novel Si2BC3N antioxidant. The microstructure evolution and the mechanical properties were evaluated in coke bed and air atmosphere. Besides, the thermal properties, including thermal shock, hot modulus of rupture, oxidation and refractories under load, were comparatively investigated. The results show that the Si2BC3N powder together with B4C and Si can satisfy the oxidation resistance requirements over a full temperature range. Si2BC3N has mainly two effects depending on the treating temperature: 1) it protects the carbon from oxidation and increases the structure integrity when the specimens are treated below 1100 °C; 2) it stimulates the growth of SiC whiskers under 1400 °C due to the enhanced reaction between SiO and CO. Consequently, the CMOR and CCS of the Si2BC3N containing specimens have been improved attributing to the structural integrity and more SiC whiskers formation, regardless of the treating atmosphere. Besides, the thermal properties such as the hot modulus of rupture, thermal shock and refractories under load are also optimized with Si2BC3N addition.