Abstract
Generally, Al2O3-SiO2 system refractories are corroded by molten aluminum which was chemically active even though the melting temperature is comparatively low. For example, a protective tube for thermocouple of porcelain and an insidewall of chamotte crucible used in experimental works are corroded by molten aluminum, and the corroded layer is changed its color to dark gray. Practically, the fact that iron crucible or graphite crucible used aluminum foundry production is depend the reason that these materials has higher corrosive resistance than Al2O3-SiO2 system refractories above described. There were many investigations on the reaction between molten aluminum and Al2O3-SiO2 system refractories. C. H. Schweinsberg, J. L. Dolph and K. J. Brondyke reported that the penetration of molten aluminum through the pore of refractory is proceeded the corrosion of refractory. By the affinity between the metal and oxygen on the thermodynamic consideration, J. G. Lindsay explained that the corrosion of refractories were proceeded by the containing of oxides which were reduced by molten aluminum. In this work, aluminum melted in the chamotte crucible and the thickness of the color changed layer was measured by comparator. The penetration of molten aluminum through the pore of refractory was recognized by X-ray diffraction method. The penetration was started by wetting which occured the reaction between the molten metal and refractory. However, the silicon nitride crucible was used and the penetration was not observed. Therefore the corrosion of refractory by molten metals was mainly caused by the penetration and the chemical reaction.
