关键词: 莫来石-刚玉浇注料, 硅溶胶结合, B₄C, 抗热震性能

Abstract: Mullite-corundum castable specimens were prepared using sintered mullite,α-Al₂O₃ micropowder,tabular corundum,and imported kyanite as raw materials,silica sol as the biner,adding different amounts of B₄C (0,0.2%,0.4%,0.6%,and 0.8%,by mass),firing at 1 450 ℃ for 3 h.Effect of the B₄C addition on properties of the castables was researched.The result shows that with the increase of the B₄C addition,the bulk density of the specimens hot treated at 1 450 ℃ changes a little,the apparent porosity decreases gradually,the cold strength increases a little,the HMOR increases obviously,the expansion decreases firstly and then increases,and the thermal shock resistance firstly increases and then decreases.The addition of B₄C promotes the formation of boron-rich liquid phases,wetting the grains of Al₂O₃ and SiO₂,resulting in small nucleation barriers,high nucleation rates and high migration rates.It is beneficial to the growth of mullite phases,leading to volume expansion and formation of a certain amount of microcracks,which improves the thermal shock resistance of the specimens.The optimal B₄C addition is 0.4%.

Key words: mullite-corundum castables, silica sol bonding, boron carbide, thermal shock resistance