Microstructure and corrosion behavior of Al2O3-Cr2O3 composites with various Cr2O3 content in Al2O3-SiO2-CaO-FeO slag

The corrosion of refractory materials by high-temperature slag has caused severe technical challenges and economic losses to the metallurgical industry. In this study, the microstructure and mechanical properties of Al2O3-Cr2O3 composites were investigated. The static crucible method was used to investigate the corrosion and infiltration behavior of a typical smelting reduction ironmaking slag for the Al2O3-Cr2O3 refractory. Corrosion test results indicate that the corrosion region of Cr2O3-Al2O3 composites is mainly composed of a corrosion and infiltration layer, and the thickness of the corrosion layer decreases significantly with increasing Cr2O3 content in the sample, whereas the thickness of the infiltration layer increases gradually. The dissolution of Al2O3 into the slag is the main reason for the severe erosion of Al2O3-Cr2O3 composites with a low Cr2O3 content. Increasing the amount of Cr2O3 can significantly improve the slag corrosion resistance of Cr2O3-Al2O3 composites, however will have a negative effect on the slag infiltration resistance, which is mainly owing to the increase in porosity of the composite refractory. The formation of the (Al, Cr)2O3 solid solution effectively inhibited the dissolution of alumina in the slag. In addition, excessive Cr2O3 content can also consume Al2O3 in the slag and form an (Al, Cr)2O3 solid solution, which improves the slag corrosion resistance of the aluminum chromium composite refractory.