Microstructural Evolution of Laser-treated Yb-based silicate environmental barrier coatings

Environmental barrier coatings (EBCs) enhance the durability of SiC-based ceramic matrix composites exposed to water-vapor-rich turbine environments and CMAS attack. However, their long-term performance is strongly influenced by microstructural features such as splat boundaries, microcracks, discontinuities, and interconnected porosity, which may promote oxidant transport or facilitate CMAS infiltration. This study explores laser post-treatment as a surface-engineering strategy to modify the near-surface microstructure of SiC/Si/Yb-based silicate EBC systems. Controlled laser processing is applied to the Yb-based silicate topcoat to systematically study how different laser parameters affect the microstructural characteristics and phase evolution of the coatings. Microstructural modifications will be assessed using cross-sectional SEM/EDS and quantitative image analysis to evaluate changes in porosity, crack density, and defect distribution. Potential phase transformation pathways will be investigated through XRD and Raman spectroscopy. By correlating laser processing conditions with microstructural developments and phase formation, this work aims to establish a framework for optimizing laser surface modification of rare-earth silicate EBCs toward improved surface integrity and environmental resistance.