M70 mullite refractory aggregate steel-based alcohol-based coating fragments after pouring was analyzed by the scanning electron microscopy and energy spectrum analysis.The results indicate that the coating in the pouring process contacts with the molten steel

which leads to the coating temperature closed to the refractory aggregate temperature

so chemical and physical changes in coating occurs to generate dense structure.The dense structure can prevent the infiltration of molten iron into the sand

which prevent effectively the formation of sticky sand to ensure the quality of the castings.