Microstructure and Thermal Properties of MoSi2 and Gd2Zr2O7 Composite Coatings on Mo-Re Alloy

Abstract:

Dual-layer thermal barrier coatings (TBCs) with ultrahigh temperature resistance were prepared on the surface of molybdenum-rhenium alloy hot-end components. The preparation of the MoSi₂-Gd₂Zr₂O₇ dual-layer TBCs was designed based on the coefficient of thermal expansion and the coating functionality, and it was completed using atmospheric plasma spraying technique. The microstructure, mechanical properties, and thermal properties were analyzed. Results indicate that the adhesion of the prepared dual-layer composite TBCs is excellent, and no noticeable cracks appear at the interface. Compared with the MoSi₂ coating with a low fracture toughness (0.88 MPa·m^1/2), the Gd₂Zr₂O₇ coating exhibits higher fracture toughness (1.74 MPa·m^1/2) and stronger resistance to crack propagation. The prepared MoSi₂-Gd₂Zr₂O₇ composite coatings have a high porosity (39%), low thermal conductivity (1.020 W·(m·K)^-1, 1200 °C), and low thermal diffusivity (0.249 mm²/s, 1200 °C). Additionally, they possess a high oxygen-vacancy concentration, which ensures excellent insulation performance.