Abstract
Penetration behavior of slags with two different kinds of chemical compositions into magnesia refractory brick was studied at 1550℃ by crucible test．Secondly，microstructure of slag penetrated magnesia refractory brick was examined．In the penetration process of calcium aluminosilicate slag without MgO，MgO grains react with the slag，resulting in the formation of spinel at the interface between MgO grains and slag． On the other hand，in the penetration process of calcium aluminosilicate slag in which spinel was supersaturated，the slag caused heterogeneous nucleation，resulting in the formation of spinel on MgO grains．lt has been clarified that these different types of reactions between MgO and slags influence greatly on the behavior of slag Penetration．
