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

摘要： 为开发高性能含碳浇注料,首先以Si粉和鳞片石墨为原料,采用熔盐隔离法,经1 350 ℃保温3 h制备了SiC包覆石墨;然后以板状刚玉颗粒、白刚玉粉、电熔镁砂粉、氧化铝微粉、Secar 71水泥、SiO₂微粉等为主要原料,分别将鳞片石墨和SiC包覆石墨引入其中,经1 100、1 600 ℃埋碳热处理后制备了Al₂O₃-MgO浇注料空白试样以及Al₂O₃-MgO-C浇注料试样,研究了石墨类型对浇注料性能的影响。结果表明:1)与未添加石墨的Al₂O₃-MgO浇注料试样相比,加入鳞片石墨的浇注料试样成型所需加水量显著增加,常温抗折强度明显降低,显气孔率明显升高,但抗热震性和抗渣性有所改善;加入SiC包覆石墨的浇注料试样加水量略有增加,常温抗折强度有所降低,显气孔率略有增加,高温强度、抗热震性和抗渣性改善。2)随着热处理温度的升高,试样的常温强度、加热永久线变化率均明显增加。3)当加入5%(w)SiC包覆石墨,热处理温度为1 600 ℃时,试样综合性能最佳,其常温抗折强度为16.9 MPa,显气孔率为16.0%,高温抗折强度为2.0 MPa,抗热震性和抗侵蚀性能良好。

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