Environmental Barrier Coatings applied by Suspension Plasma Spraying

Environmental barrier coatings (EBCs) are protective ceramic coatings applied on Ceramic Matrix Composites (CMCs) to prevent surface recession in steam and corrosive environment. Ytterbium disilicate (YbDS) has garnered significant attention as a promising topcoat material for EBCs due to its high thermomechanical stability, resistance to oxidation and corrosion in harsh environments. In this work, a systematic study was conducted to assess the process parameter impact on the microstructure of suspension plasma sprayed YbDS coatings on SiC substrates with a Si bond coat, by varying plasma power and total gas flow rate. The results showed that these process parameters have a significant influence on phase constitution, microstructure and porosity of the YbDS coatings. The effect of thermal post-treatment on the above was also investigated. In addition, the YbDS coatings were subjected to long-term thermal exposure to ascertain the corresponding changes in microstructure and thermally grown oxide layer.