Improvement of the alkali corrosion resistance and mechanical properties of corundum castables by coating of Li2O-Al2O3-SiO2 glaze

Abstract

In terms of improving the alkali corrosion resistance of corundum castables, coating technology is applied to preparing the excellent properties of corundum castables with a glaze layer. The work focuses on the effect of the ratio of Al2O3/SiO2 on the properties of Li2O-Al2O3-SiO2 glazes. Furthermore, the influence of Li2O-Al2O3-SiO2 glazes on the alkali corrosion resistance of corundum castables is investigated. The results show that at a high temperature with increasing of the ratio of SiO2/Al2O3 in Li2O-Al2O3-SiO2 glazes, the viscosity and amount of liquid phase in the glaze increase gradually, which has a great influence on the quality of the glaze at a high temperature. And as the ratio of Al2O3/SiO2 in the glaze is between 6 and 8, the apparent porosity of corundum castables with the glaze layer decreases significantly resulting in preventing the permeation of alkali vapor into the castables, which can improve the alkali corrosion resistance and mechanical properties of corundum castables dramatically. Moreover, as the thermal expansion coefficient of the matrix is higher than the glaze layer, the compressive residual stress (tangential direction) will exist in the glaze layer, resulting in enhancing crack bifurcation, which is beneficial to improving the properties of corundum castables.