不同基质组成的刚玉-尖晶石浇注料性能研究

Properties of corundum- spinel castables with different matrix compositions

以板状刚玉、电熔尖晶石和铝酸钙水泥为原料，设计了尖晶石细粉质量分数分别为O、7．5％、15％和22．5％的4组浇注料，每组浇注料又依水泥量的不同设计了m（CaO）／m（A1203）分别为0．03、0．06、0．09、0．15、0．18的5个配方，制备了不同基质组成的刚玉～尖晶石浇注料试样，系统研究了试样经1600cC3h处理后的性能（尤其是高温抗折强度和抗热震性）及基质显微结构。结果表明：1）高温下尖晶石与基质中的A1203发生固溶而影响浇注料的高温强度，加入7．5％～15％质量分数的尖晶石细粉时，基质中的A1203与尖晶石固溶程度较大，基质的结合强度较强，高温强度明显较高；而加入尖晶石较多时，A1203，量相对降低，减弱了固溶产生的结合，形成了“松散”的基质结构，可有效提高浇注料的抗热震性，因此加入22．5％质量分数尖晶石细粉的浇注料抗热震性最优。2）随着铝酸钙水泥的增加，浇注料的体积密度逐渐减小，常温抗折强度和弹性模量逐渐降低；当基质中m（CaO）／m（3_1：0，）=0．09时，基质中刚玉细粉和A12O3，微粉与水泥在高温下全部反应，生成了大量交错分布的板状六铝酸钙，浇注料的高温抗折强度最高，抗热震性最好。

Four groups of castables with different spinel fines contents( 0,7. 5%,15% and 22. 5%,in mass, the same hereinafter) were designed using tabular corundum,fused spinel and calcium aluminate cement as main starting materials. Each group consisted of five formulations with different m( CaO) /m( Al 2 O 3) rati- os( 0. 03,0. 06,0. 09,0. 15 and 0. 18) according to the cement amount to prepare corundum- spinel castable specimens with different matrix compositions. Properties( especially hot modulus of rupture and thermal shock resistance) and matrix microstructures of the castable specimens fired at 1 600 ℃ for 3 h were studied. The results show that:( 1) the hot strength of the castable is influenced by the solid solution between spinel and alumina in the matrix,the specimens with 7. 5%- 15% spinel fines show higher bond- ing strengths in the matrix as a result of high level solid solubility between spinel and alumina,thus showing strikingly improved hot strength; when a large amount of spinel fines is added to the matrix of castables,the relative content of alumina in the matrix decreases,as a result,the solid solution bond is weakened,forming of a 'loose'microstructure in the matrix,which can improve the thermal shock resistance of the castable effectively,so the castable with 22. 5% spinel fines shows superior thermal shock resistance;( 2) the bulk density,cold modulus of rupture and elasticity modulus of the castables decrease gradually with the calci- um aluminate cement addition increasing; when m( CaO) /m( Al 2 O 3) =0.09 in the matrix,the castable per- forms the highest hot strength and the best thermal shock resistance due to the complete reaction of the corundum fines and alumina powder with cement in the matrix at high temperatures,forming numerous plate-like calcium hexaluminate crystals interweaving in the matrix.