Environmental barrier coatings using the low pressure plasma spray process

Environmental barrier coatings (EBC) for Si based ceramic matrix composites (CMCs) will play an increasingly important role in next generation gas turbine engines. A high performance and highly durable EBCs system depends significantly on the materials composition, coating process and coating architecture. Low pressure plasma spraying (LPPS) technology has been well established in industry for many years. Depending on the chamber pressure and powder feedstocks selection, dense and columnar microstructure coatings can be obtained respectively using the LPPS process. In this study, multilayer environmental barrier coatings on SiC ceramic substrate were designed and developed using the LPPS process. Design of experiment were carried out to optimize the process parameters for each layer. Phase composition, microstructure and coating chemistry of as-sprayed and heat-treated coatings were evaluated. High temperature thermal stability of the EBCs system were also investigated.