Enhanced corrosion and oxidation resistance of environmental barrier coatings through densification and high crystallization at optimized deposition temperatures

Abstract

To withstand extreme aero gas turbine environments, environment barrier coatings (EBCs) must strongly resist high-temperature oxidation and water-vapor corrosion. A highly dense and crystalline structure is key to durability. This study explores ytterbium disilicate and monosilicate hybrid coatings fabricated using different plasma spraying techniques and deposition temperatures to assess their effects on density, crystallinity, and water-vapor corrosion resistance. Results revealed that low-heated (∼200 ℃) air plasma sprayed (APS) coatings had high porosity (7.3 %), multi-cracked structures, and mostly amorphous (above 90 %), making them highly susceptible to degradation. In contrast, low-pressure plasma spraying (LPPS) with low input power minimized silicon evaporation during deposition and increased crystallinity to 83 % by raising deposition temperature to 800 ℃. Highly dense and crystallized LPPS coatings remained structurally integrity after 300 h exposure in 90 vol%H₂O-10vol%O₂ at 1350 ℃, effectively reducing silicate decomposition, cracking, and silicon oxidation, extending oxidation resistant life by more than 10 times.