Study On Preparation And Properties Of Al₂O₃ NiAlW/NiAlW Thermal Barrier Coatings

The feasibility of Al2O3·Ni Al W/Ni Al W coating applied to certain parts of an aviation engine was mainly studied in this paper by comparing the coatings of domestic and abroad. The coating preparation materials were Al2O3·Ni Al W and Ni Al W flexible wire, and the preparation process were the flame spraying.Al2O3·Ni Al W/Ni Al W coating use the nickel, aluminum and tungsten-based alloy as the base material, and the nickel, aluminum and tungsten-based alloy and ruby together constitute the "metal ceramic" as the surface layer material, this kind of bottom layer and the surface layer material was used for the first time in the domestic.The applicability of Al2O3·Ni Al W and Ni Al W flexible wire on the preparation of Al2O3·Ni Al W/Ni Al W coating by flame spraying and influences to coating under different wire feeding voltage(9V, 9.5V, 10 V, 11V) and at coating angle(30, 60, 90)were studied, Main phase structure of the coating is β-Ni Al 、Ni and γ- Al2O3, the appearance, chemical composition, microstructure of the coating both made domestic and abroad were compared and analyzed, The coating microstructure was uniform and the performance was good. The result shows applicability of both domestic and abroad flexible wire was almost the same; the domestic wire shows better process applicability.The thermal diffusivity, specific heat, density, thermal conductivity, thermal expansion coefficient, bonding strength, high temperature oxidation resistance, gas thermal corrosion test and other tests were compared and analyzed. The results showed that the performance of coatings both domestic and abroad was almost the same; the most important is that the domestic coating shows the better process applicability, excellent comprehensive properties especially for good thermal insulation, oxidation resistance and excellent high temperature corrosion resistance.Some performance indicators were even better than similar foreign coatings,As in200℃~1000℃ range, domestic coating thermal conductivity is decreased to 1.29W·m-1·K-1, foreign coating thermal conductivity is 1.97 W·m-1·K-1。The Al2O3·Ni Al W/Ni Al W flexible wire was used for spraying experiment with flame spraying method. Combining with the concrete structure of the certain parts to carry on the typical parts spraying, the application performance of Al2O3·Ni Al W/Ni Al W coatings was verified. The thermal barrier coatings of Al2O3·Ni Al W/Ni Al W prepared by this process showed that coatings is smooth in appearance, uniform in thickness without blocking and falling off, and the coating continuity at steps and the transmission of air film hole is good, which can meet the requirements of the working condition, and can guarantee the design life of the parts.The long life service requirements of domestic made thermal barrier coatings Al2O3·Ni Al W/Ni Al W applied to certain parts was ensured.