氯化镁对铝酸钙水泥结合浇注料性能的影响

Influence of magnesium chloride on properties of calcium aluminate cement bonded castables

为了改善铝酸钙水泥结合浇注料的高温体积稳定性,以w(Al2O3)≥99.5%的板状刚玉为骨料,w(Al2O3)≥99.7%的活性Al2O3微粉和板状刚玉细粉(≤0.044 mm)为基质,以铝酸钙水泥Secar 71为结合剂,添加适量氯化镁制备铝酸钙水泥结合浇注料,分别在1 100℃3 h和1 450℃3 h进行热处理,测定浇注料试样的常温物理性能,并分析基质试样的物相组成和显微结构。结果表明:氯化镁的加入会导致浇注料经高温处理后的体积密度下降,显气孔率升高,并降低浇注料高温处理后的力学性能;但是,含氯化镁的浇注料经高温处理后的线膨胀较小。通过显微结构分析发现,在含氯化镁的浇注料基质中有发育良好的板片状CA6,氯化镁分解所产生的孔隙可以为高温下CA6的形成提供部分可膨胀的空间,从而降低CA6形成所带来的体积膨胀,有利于改善浇注料经高温处理后的体积稳定性。

To improve the volume stability at high tempeartures,calcium aluminate cement bonded castables were prepared using tabular alumina （Al2O3≥99.5 mass%）as aggregate,reactive alumina micropowder （Al2O3≥99.7 mass%）,and tabular alumina fines （≤0.044 mm）as matrix,calcium aluminate cement （Se-car 71）as binder,and magnesium chloride as additive.The castables were fired at 1 100 ℃ and 1 450 ℃for 3 h,respectively.Then physical properties of the castables were tested,and phase composition and mi-crostructure of castable matrix specimens were analyzed.The results show that the castable with magnesi-um chloride has the decreased bulk density,the increased apparent porosity and the decreased mechani-cal properties and linear expansion after firing at high temperatures.It is found in the microstructure that the well developed tabular CA6 crystals disperse in the matrix of the castable with magnesium chloride.There-fore,these voids generated from the decomposition of magnesium chloride in the matrix provide expansion spaces for CA6 at high temperatures and consequently decrease the volume expansion generated from the formation of CA6 ,and thus improve volume stability of the castables after firing at high temperatures.