Study on properties of Hf6Ta2O17/Ta2O5 system: A potential candidate for environmental barrier coating (EBC)

Ta2O5 doped Hf6Ta2O17 system (Hf6Ta2O17/Ta2O5) is considered to have potential application prospect in the field of aero-engine. We herein focus on the thermo-physical, mechanical properties and CMAS corrosion resistance of Hf6Ta2O17/Ta2O5 to systematically evaluate the possibility for the application of environmental barrier coating (EBC). By changing the content of Ta2O5, the gradient adjustment of thermal expansion coefficient can be realized while maintaining low thermal conductivity (1.5-2.2 W/(m center dot K)). The introduction of Ta2O5 significantly reduces the modulus and improves the fracture toughness. Single-phase Hf6Ta2O17 shows excellent corrosion resistance against molten calcium-magnesium-alumina-silicate (CMAS). The crystallization of CaTa2O6 and HfSiO4 is the important factor to prevent further corrosion. The introduction of Ta2O5 weakens the ability to prevent Si penetration and greatly increases the thickness of the corrosion layer. The results highlight the merit of Hf6Ta2O17/Ta2O5 system as potential candidate for multi-layer gradient coating on the surface of ceramic matrix composites.