Interactions of magnesia castables used in steelmaking with calcium aluminate slag

Slag penetration into a magnesia refractory castable was investigated by the crucible test method. A synthetic calcium aluminate slag system has been used to corrode a commercial magnesia mix refractory for 1, 2, 3, 4, 5 and 6 h at 1450°C and 1600°C. It has been shown that the penetration rate was controlled by a diffusion mechanism at 1450°C, capillaries being the main channels of initial slag penetration into the refractory. In the penetration process, calcium silicate was formed on the surfaces of MgO grains, and around them by reaction between the grain boundary and mayenite, as a main phase of slag with a low melting point. Dissolution of the refractory components in the slag supported the penetration process at 1600°C. In this case, dissolution of the refractory components in the slag not only makes new open channels, but also changes the local slag composition, resulting in a decrease of viscosity and an increase of surface tension of the sla