关键词: Al₂O₃-MgO浇注料, 鳞片石墨, SiC包覆石墨, 抗热震性

Abstract: To develop high-performance carbon-containing castables,SiC-coated graphite was prepared using Si powder and flake graphite as raw materials by a molten salt isolation method firing at 1 350 ℃ for 3 h.Then,flake graphite and SiC-coated graphite were introduced into tabular corundum particles,white corundum powder,fused magnesia powder,alumina micropowder,Secar 71 cement,and silica micropowder to prepare Al₂O₃-MgO castable blank samples and Al₂O₃-MgO-C castable samples by carbon embedded heat treatment at 1 100 and 1 600 ℃.The effect of different graphite types on the properties of the castables was studied.The results show that:(1)compared with the Al₂O₃-MgO castable sample without graphite,the castable sample with flake graphite has significantly increased water demand for molding,significantly reduced cold modulus of rupture,significantly increased apparent porosity but improved thermal shock resistance and slag resistance;the castable sample with SiC-coated graphite has slightly increased water demand,decreased cold modulus of rupture,slightly increased apparent porosity,and improved hot strength,thermal shock resistance,and slag resistance;(2)with the increase of the heat treatment temperature,the cold strength and permanent linear change rate on heating of the samples increase significantly;(3)when 5 mass% SiC-coated graphite is added and the heat treatment temperature is 1 600 ℃,the comprehensive properties of the sample are the best: the cold modulus of rupture is 16.9 MPa,the apparent porosity is 16.0%;the hot modulus of rupture is 2.0 MPa;and the thermal shock resistance and corrosion resistance are good.

Key words: Al₂O₃-MgO castables, flake graphite, SiC-coated graphite, thermal shock resistance