A Review on Environmental Barrier Coatings: History, Current State of the Art and Future Developments

The increasing demand for more efficient and environmental-friendly gas turbines has driven the development of new strategies for material development. SiC/SiC ceramic matrix composites (CMCs) can fulfil the stringent requirements; however, they require protection from the operating environment and debris ingested during operation. Environmental barrier coatings (EBCs) are a protective measure to enable the CMCs to operate under harsh conditions. EBC-coated CMCs will enable an increased efficiency and reduced pollutant and CO2 emissions. In this review, the fundamentals of SiC/SiC ceramic matrix composites degradation in steam environments and under the presence of molten alkali salts, namely CaO-MgO-Al2O3-SiO2 (CMAS), are first presented. Then, a summary of EBCs along with a comprehensive summary of the current compositions and their interactions with steam and molten salts is presented. Finally, an overview of the latest research directions for the potential next generation of EBCs are outlined