Influence of surface modification on isothermal oxidation behavior of EB-PVD NiAl coating
(1.Beijing General Research Institute of Mining and Metallurgy, Beijing 100044, China2.School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics,Beijing 100083, China3.北京航空航天大学材料科学与工程系，北京100083)
Abstract: The isothermal oxidation behaviors of the as-deposited NiAl coating on the nickel-based superalloy by electron beam physical vapour deposition(EB-PVD) and the NiAl coating after surface modifications of grinding and polishing were investigated. The as-deposited coating shows the least mass gain, the initially formed θ-Al2O3 scale spalls after only 1 h, and the succeeding scale formed is coarse and discontinuous and thus can not be used as protective coatings. Among the two surface-modified coatings, the ground coating results in the highest oxide growth rate, which is consistent with the SEM results where the scale spalls heavily and many voids appear between the scale and the NiAl coating. The scale spallation and void formation mechanisms during isothermal oxidation test of EB-PVD NiAl coating were also discussed.
Key words: thermal barrier coatings(TBCs); EB-PVD; NiAl; oxidation