再生铬刚玉骨料对刚玉-尖晶石浇注料性能及显微结构的影响

Effect of recycled chrome corundum aggregates on properties and microstructure of alumina-spinel castables

为研究再生铬刚玉在刚玉-尖晶石浇注料中应用的可能性,采用粒度为8~5、5~3、3~1和≤1 mm的电熔白刚玉,≤0. 074 mm的板状刚玉,≤1、≤0. 044 mm的电熔尖晶石等为主要原料,纯铝酸钙水泥为结合剂,同时添加适量的复合减水剂,按骨料与细粉质量比60∶40配料。研究了以多粒级再生电熔铬刚玉骨料逐步替代等粒级白刚玉骨料,其加入量(w)依次为15%、30%、45%和60%时,对刚玉-尖晶石浇注料110℃烘干和1 550℃处理后的抗折强度、耐压强度、加热永久线变化率,以及1 550℃处理后的高温抗折强度、抗热震性等的影响,并对部分试样进行显微结构分析。结果表明:1)与白刚玉骨料相比,再生铬刚玉骨料具有更低的显气孔率和更高的致密度,对浇注料的流动性有利; 2)再生铬刚玉骨料和白刚玉骨料在物相组成、分布以及热膨胀行为上的差异为通过骨料复配来优化浇注料的性能提供了依据,其中,再生铬刚玉和白刚玉加入量均为30%(w)时的等量复配模式有利于提高浇注料的高温强度,而再生铬刚玉加入量(w)为15%或45%的主副搭配型复配模式对改善浇注料抗热震性更为有益; 3)在加水量相同条件下,以再生铬刚玉骨料为主的浇注料经高温处理后生成的CA6的结晶形态更好。

This work explores the application feasibility of recycled chrome corundum aggregates in aluminaspinel castables. White fused alumina aggregates （8 -5 mm,5 - 3 mm,3 - 1 mm and ≤1 mm）,tabular alumina fines （≤0.074 mm）,and fused spinel （≤1 and≤0.044 mm） were used as main starting materials, pure calcium aluminate cement as the binder,and adding certain amount of composite water reducer. The ratio of aggregates and fines is 60：40 by mass. Recycled chrome corundum aggregates with different particle sizes were incorporated into alumina-spinel castables to replace white fused alumina aggregates with the same particle sizes. The effect of recycled chrome corundum addition （15% ,30% ,45% and 60% by mass） on the modulus of rupture, crushing strength, permanent change on heating as well as the hot modulus of rupture at 1550 ℃ and the thermal shock resistance of the specimens dried at 110℃ and hot treated at 1 550℃ was researched. The microstructure of some specimens was observed by SEM. The results show that （1） compared with the white alumina aggregates,the recycled chrome corundum aggregates have lower apparent porosity and higher density,which is beneficial for flowability; （2）recycled chrome corundum aggregates and white alumina aggregates differ in terms of phase composition ,distribution and thermal expansion,which provides the basis to optimize the castable properties by adjusting the aggregates incorporation;the hot strength of the castables can be enhanced by adding 30% recycled chrome corundum aggregates and 30% white fused alumina;the thermal shock resistance can be improved by adding 15% or 45% recycled chrome corundum aggregates; （3）with the same water addition,the CA6 generated in the hot treated castable specimen using chrome corundum aggregates exhibits a better crystalline degree.