2026 Avci Laser Glazed Environmental Barrier Coating

Environmental barrier coatings (EBCs) were developed to protect SiC/SiC CMCs used in the hot sections of new-generation gas turbine engines from corrosion. Plasma-sprayed YbSi is deposited as an EBC top layer, mostly in the amorphous phase. Plasma spraying inherently creates cracks and porosity on the surface. These disadvantages prompted the study to explore laser glazing as a solution. The surfaces of plasma-sprayed EBCs were modified with various laser processing parameters, ultimately glazing the entire EBC surface using optimum parameters identified. Hot corrosion and CMAS corrosion tests were performed on laser-glazed EBCs, revealing that laser glazing transformed the YbSi structure from amorphous to crystalline, generating a smooth and dense layer. Although characterizations after hot corrosion tests showed that the laser-modified sample exhibited structural deterioration with increased penetrability of corrosive salts, leading to performance degradation compared to as-sprayed coatings, laser modification provided significant benefits against CMAS corrosion. The crystallized structure effectively restricted corrosive glass phase penetration, resulting in a 50% enhancement in corrosion resistance relative to the as-sprayed sample. Thus, while laser surface modification successfully achieved the desired crystallization critical for CMAS environments, it negatively impacted hot corrosion resistance due to structural issues, indicating a need for further optimization.