Steam Corrosion Behavior of Ytterbium Disilicate Environmental Barrier Coatings Prepared by APS and LPPS Processes

ABSTRACT This work studies the steam corrosion behavior of tri‐layer /mullite/silicon environmental barrier coatings (EBCs) in a high‐temperature water vapor–oxygen environment ( and 90 vol.% –10 vol.% ). Atmospheric plasma spraying (APS) and low‐pressure plasma spraying (LPPS) techniques were utilized to prepare the coatings for comparison. It was found that the fabrication process plays a crucial role in maintaining the environmental durability of the EBCs. Despite their dense as‐deposited microstructures, LPPS‐deposited coatings exhibited inferior corrosion resistance due to the elevated Si activity of the top‐coat, intensified interaction with the mullite interlayer, and the formation of numerous fine pores. The growth rate of thermally‐grown oxide in LPPS‐deposited coatings was approximately 2.7 times greater than in APS‐deposited coatings. Additionally, the mullite interlayer negatively impacted the corrosion resistance by compromising the stability of the top‐coat through chemical interaction.