High temperature behavior of HfSiO4 subjected to calcium-magnesium-alumina-silicate (CMAS) and high-velocity water vapor

HfSiO4 is considered as a candidate for environmental barrier coating (EBC), but there is a lack of comprehensive evaluation of its resistance against corrosive medium. We herein study the behavior of HfSiO4 against CMAS melt and high-velocity water vapor. HfSiO4 shows poor resistance to CMAS attack. Si diffusion occurs during CMAS attack, which leads to the formation of HfO2 and CaSi2O5. HfSiO4 decomposes to form SiO2 and HfO2 under the scouring of water vapor, in which SiO2 forms volatile hydroxide and is taken away by high-velocity steam. HfSiO4 is not the preferred system for surface layer of EBC system and is expected to be used as intermediate transition layer.

Automated summary

In this study, the corrosion resistance of HfSiO4 in different corrosive mediums was evaluated. It was found that HfSiO4 showed poor resistance to CMAS attack and decomposed in high-velocity water vapor. Therefore, HfSiO4 is not suitable as the surface layer of an EBC system but can be used as an intermediate transition layer.