棕刚玉和矾土对Al_2O_3-SiO_2系无水泥浇注料结构和性能的影响

Effects of brown fused alumina and bauxite on properties and microstructure of zero-cement Al_2O_3-SiO_2 castables

以棕刚玉和特级矾土为主要原料,以Al2O3微粉、SiO2微粉和纯铝酸钙水泥为结合体系,研究了棕刚玉和特级矾土加入量对Al2O3-SiO2系无水泥浇注料烘干及1 250℃3 h烧后性能的影响,并进行了显微结构分析和讨论。结果表明:在本试验条件下,Al2O3-SiO2系无水泥浇注料中特级矾土最佳加入质量分数为12.5%左右,1 250℃下的热态抗折强度可达22.1 MPa。Al2O3-SiO2系无水泥浇注料中莫来石的生成机制属于溶解-沉淀,且其热态抗折强度与原位莫来石生成情况密切相关。与棕刚玉相比,特级矾土更有利于莫来石的生成,故加入特级矾土更有利于提高无水泥浇注料的热态抗折强度。

Using brown fused alumina and high grade bauxite as main starting materials,ultrafine alumina,silica fume,and pure calcium aluminate cement as bonding system,the effects of brown fused alumina and high grade bauxite additions on the properties and microstructure of zero-cement Al2O3-SiO2 castables after dried at 110 ℃ and fired at 1 250 ℃ for 3 h were studied.The microstructure was analyzed and discussed.The results show that the hot modulus of rupture of zero-cement Al2O3-SiO2 castables at 1 250 ℃ is up to 22.1 MPa when the bauxite addition is optimum at 12.5 wt%.The mullite formation mechanism in this castables belongs to dissolution-precipitation mechanism and the hot modulus of rupture of the castables is closely related to in-situ mullite formation.Compared with brown fused alumina,the high grade bauxite is more helpful to in-situ mullite formation and improvement of hot modulus of rupture of the castables.