轻烧铝矾土骨料对Al_2O_3-SiO_2质超低水泥浇注料性能的影响

Effect of mild-calcined bauxite aggregates on properties of Al_2O_3-SiO_2 ULC castables

为实现Al2O3-SiO2质浇注料的轻量化而采用部分轻烧铝矾土骨料，将伽（Al2O3）为71％的铝矾土生料分别经900和1100℃轻烧，破碎分级成5—3、3～1和≤1mm的骨料。在矾土基超低水泥浇注料基础配比中，分别以质量分数15％、30％和45％的轻烧骨料等量取代特级矾土熟料，检测了各项常规性能并借助扫描电镜观察了显微结构。结果表明：随轻烧骨料加入量的增多，浇注料的需水量增加，显气孔率增加，体积密度下降；1350℃烧后的加热永久线变化率呈下降趋势，但即使加入轻烧料高达45％（W）时，仍能保持残余膨胀；烘干后的抗折强度有所下降，但对1000和1350℃烧后抗折强度影响不大，甚至1000℃烧后的强度有所增加；1300℃的高温抗折强度有所降低。对于使用温度在1350℃以下气氛炉用铝硅质浇注料，用900～1100℃轻烧铝矾土骨料部分取代其熟料骨料，可实现浇注料的轻量化。

For the purpose of reducing Al2O3-SiO2 castables＇ weight by using mild-calcined bauxite aggregate,raw bauxite with 71% （in mass,the same hereinafter） Al2O3 was calcined at 900 and 1100℃, respectively,then crushed into sizes of 5-3 mm, 3-1 mm and under 1 mm as aggregates. They were added into a bauxite based ULC castable as reference to replace special grade bauxite grog as counterparts by 15% ,30% and 45%, respectively. Regular properties of the castables were tested and the microstructure of related samples was observed by SEM. With increased addition of the mild-calcined aggregates,water demand for casting becomes higher,apparent porosity increases and bulk density decreases;positive value of permanent linear change after firing at 1 350 ℃ declines,nevertheless even at as high as 45% addition of the aggregates,residual expansion can still be maintained;CMOR after drying decreases,while the addi- tion has little influence on CMOR after firing at 1 000 and 1 350 ℃,with even enhanced CMOR after firing at 1 000℃;HMOR at ; 300℃ tends to decrease. Weight reduced aluminosilicate castables used for atmospheric furnaces with service temperatures under 1 350 ℃ can be achieved by using 900-1 100 ℃ mild-calcined bauxite aggregates,worth of practical application trails.