High temperature corrosion of SiC-CaAl12O19 composite refractory by coal slag

Corrosion processes of SiC-CaAl ₁₂O ₁₉(CA ₆ ) composite refractory were carried out by both static crucible test and rotary drum test at 1500 °C and 1600 °C under a reducing atmosphere, respectively. The corrosion mechanism of the SiC-CA ₆ refractory was analyzed by means of X-ray diffraction(XRD) and scanning electron microscope(SEM). The results show that the corrosion temperature and condition had significant influence on the slag resistance of the SiC-CA ₆ refractory. But no matter which corrosion methods and which temperatures under the condition of this experiment, the SiC-CA ₆ refractory exhibited good penetration resistance even though a little corrosion appeared at a higher temperature. During the corrosion process, most of Fe containing oxide in slag could be reduced by CO in atmosphere and SiC in samples to form Fe-Si metal alloys, which precipitated at the interface between the slag and composites. The penetrated slag could react with the SiO ₂ produced by SiC oxidation and the CA ₆ matrix to form CaAl ₂Si ₂O ₈ and corundum, filling the pore inside the samples and causing the densification of the reaction layer. Because of the reaction between infiltrated slag and SiC-CA ₆ refractory, the composition and properties of local slag changed and inhibited the further penetration.