Laser-induced microstructure and phase composition modification of YbDS/Si environmental barrier coatings for enhanced CMAS corrosion resistance

Calcium-magnesium-alumina-silicate (CMAS) corrosion threatens the long-term performance and service stability of environmental barrier coatings (EBCs) for SiC_f/SiC ceramic matrix composites (CMCs). In this work, ytterbium disilicate (YbDS)/Si EBCs are prepared by atmospheric plasma spraying (APS), and the role of laser treatment on their CMAS resistance is investigated. Laser treatment creates a smooth and dense YbMS-rich layer at surface of the YbDS coating. Short-term corrosion results demonstrate that molten CMAS infiltrates to a depth of ∼23 µm in the untreated YbDS coating, but is blocked at the surface of the laser-treated sample. After long-term corrosion, the untreated YbDS coating is almost fully permeated, whereas nearly one-third of the laser-treated coating remains intact. Further investigation demonstrates that, apart from the reduced roughness and denser surface caused by laser remelting, the YbMS-rich layer also contributes to the improved CMAS resistance. This work reveals that laser treatment simultaneously modifies the microstructure and phase composition of the YbDS coating, providing fundamental insights and practical guidelines for the development of advanced EBCs with superior CMAS resistance.