Significantly improved water-oxygen corrosion resistance of SiC/SiC composite modified by Si-B-Mo-Y using reactive melt infiltration

Si-B-Mo-Y modified SiC/SiC composites were prepared by reactive melt infiltration (RMI) process to study their high-temperature water-oxygen corrosion resistance, and to compare them with SiC/SiC composites prepared by RMI using Si. The results show that the corrosion rates of the modified composites are only 1/9, 1/10 and 1/3 of those of the comparison samples at 1200°C, 1300°C and 1400°C, respectively, which is attributed to the higher densification of the modified composites. More importantly, the modified composites were able to form borosilicates, which effectively healed the oxide film defects; meanwhile, yttrium silicate inhibited the reaction between borosilicates and water vapor.