Environmental Barrier Coatings Deposited by Suspension Plasma Spraying

ABSTRACT

Fully crystalline, dense environmental barrier coatings (EBCs) are required to protect SiC‐based ceramic matrix composites, which are the advanced structural materials for hot‐section components of gas turbines. Thermal spray technologies, which have been widely used for depositing thermal barrier coatings, are also applied to deposit EBCs. Avoiding the segmental cracks is one of the main challenges in depositing thermal sprayed EBCs. In this work, suspension plasma spraying (SPS) was used to deposit EBCs on the SiC substrates. The combustion of an ethanol‐based suspension can bring plasma additional enthalpy. As a result of that, extremely high deposition temperatures (above 1200°C) could be achieved. At such high deposition temperatures, fully crystalline crack‐free Yb ₂ Si ₂ O ₇ coatings were successfully obtained. However, A relatively high amount of Yb ₂ SiO ₅ phase was observed in the as‐sprayed coatings. The high amount of the Yb ₂ SiO ₅ phase was attributed to the high surface ratio of the particles formed during the suspension plasma spray.