Enhanced Water Vapor Resistance of High-Entropy T/Ebcs with Strain Tolerant/Dense Composite Structures Fabricated by Ps-Pvd

Abstract

Third-generation environmental barrier coatings (EBCs) face the challenge of inadequate water vapor resistance in high-temperature water vapor environments, which restricts the service temperature of ceramic matrix composite hot-section components. Currently, fourth-generation thermal/environmental barrier coatings (T/EBCs) are under development. In this study, EBCs and T/EBCs were prepared using plasma spray physical vapor deposition (PS-PVD). Dense yet crack-free Si and Yb2Si2O7 (YbDS) layers were produced to eliminate fast diffusion pathways for corrosive species. Furthermore, a feather-shaped high-entropy ceramic (HEC) layer composed of (Y0.2La0.2Nd0.2Sm0.2Eu0.2)2Zr2O7 (YLNSE) was deposited above the dense EBCs, mitigating the mismatch in the coefficient of thermal expansion through strain-tolerant structures while providing thermal insulation and protection to the underlying EBCs. The water vapor corrosion behaviors at 1400 °C were investigated for durations of 50 h, 150 h, and 300 h to elucidate the corrosion mechanisms of EBCs and T/EBCs. The elevated activation energy and reduced thermal conductivity of the HEC material, along with the strain-tolerant/dense composite structure, contributed to the enhanced water vapor resistance of the T/EBCs. This study demonstrates that the synergy of material and structural design can maximize the functionality of multi-layer systems, providing guidelines for the application of advanced coating systems, such as HEC T/EBCs, in aero-engines and gas turbines.

Keywords: T/EBCs, high-entropy ceramic, water vapor corrosion, strain-tolerant structure, dense structure