Innovative method to modify an APS-formed lamellar ceramic coating into a fully dense and columnar microstructure

An innovation in this work considers the use of a plasma electrolytic oxidation (PEO) process to densify an atmospheric plasma sprayed (APS) Yttria coating. Coatings characteristics have been studied using an SEM, image analysis, coating color and reflectance, dielectric breakdown and DC potentiodynamic corrosion testing. Microstructural analysis revealed substantial pore sealing, crack-bridging and the formation of a dense, adherent interfacial oxide layer that penetrates the APS-Y 2 O 3 microstructure. The hybrid APS + PEO coating exhibited significantly reduced porosity, improved electrical insulation and corrosion resistance. Notably, the interfacial Al 2 O 3 formation, achieved through PEO is expected to reduce the dependence on a traditional bond coat requirement, offering a simplified coating architecture with improved coating adhesion and cohesion. The findings demonstrates PEO as a promising post-treatment route for producing dense, durable Y 2 O 3 coatings suitable for advanced industrial semiconductor applications that require high resistance to etching (corrosion), reactive gas erosion with minimal particulate generation.