Effect of Al2O3-MgAl2O4 composite aggregate on slag resistance of corundum-spinel castables
To study the effect of the Al2O3-MgAl2O4 composite aggregate on their slag resistance,corundum-spinel castables were prepared using the tabular corundum aggregate and Al2O3-MgAl2O4 composite aggregate,respectively,with or without spinel fine powder in the matrix.Firstly,the reaction thermodynamics between the tabular corundum aggregate or Al2O3-MgAl2O4 composite aggregate and slag at 1 600 ℃ was calculated using the FactSage reaction thermodynamics software,and the slag resistance of the two aggre-gates was studied using the soaking method.Secondly,the effect of the two aggregates on the slag resist-ance of the castables was studied by the static crucible method.The results show that compared with the tabular corundum aggregate,the Al2O3-MgAl2O4 composite aggregate has finer and fewer cracks in the corrosion layer,suggesting the resistance to peel off after slag corrosion.There are both CA6 and spinel phases in the transition layer,and Fe and Mn elements solid dissolve in spinel,indicating that the aggre-gate not only blocks slag corrosion by forming a CA6 layer,but also reduces the viscosity of the slag by ab-sorbing substances such as FeO and MnO in the slag through spinel,thereby playing a role in resisting slag corrosion.Replacing the tabular corundum aggregate with the Al2O3-MgAl2O4 composite aggregate,the corroded and penetrated area percentages of the corundum-spinel castables decrease,especially,in-troducing spinel into both the matrix and aggregate can effectively improve the slag resistance of the castables.
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