금속간화합물 TiAl의 고온산화거동 및 기계적성질에 미치는 Al-21Ti-23Cr 코팅의 효과

Abstract

Ti-48Al specimens were coated with Al-21Ti-23Cr film at 200W, 0.8Pa and 573K by RF magnetron sputtering. The oxidation behavior of the coated specimens was investigated through isothermal and cyclic oxidation tests, and the tensile deformation properties of the uncoated and the coated specimens were also investigated before and after oxidation. The isothermal and cyclic oxidation curves showed that the AI-21Ti-23Cr film was very effective in decreasing the oxidation rate of the Ti-48Al at 1273 K. This excellent oxidation resistance is attributable to the formation of a protective Al₂O₃, layer on the surface of the Al-21Ti-23Cr film. From the tensile test, it was found that the protective Al₂O₃, layer on the surface of the Al-21Ti-23Cr film enabled the Ti-48Al to maintain its tensile properties in an oxidizing environment. Moreover, from the microhardness test, it was also found that the Al-21Ti-23Cr film suppressed the embrittlement of the Ti-48A1 during oxidation. Although extensive cracking with a transverse direction was observed on the surface of the film, the delamination of the film from the substrate and the spallation of the Al₂O₃ scale were not observed. Thus, it is suggested that the adhesion of the Al₂O₃ scale on the Al-21Ti-23Cr film and the Al-21Ti-23Cr film on the Ti-48Al is excellent before and after oxidation.