Abstract: In order to improve the high temperature oxidation resistance of superalloy, NiCrAlY coatings were deposited on DZ22B superalloy by cathode arc ion plating. Scanning electron microscopy was used to observe the surface and cross-section morphology of the coatings. The volumetric analysis was applied to test the composition of the coating, X-ray diffraction was used to analyze the phase composition of the coating, and adhesion of the coatings was measured by universal testing machine. The results show that the thickness of NiCrAlY coating is about 50 μm, and the coating is compact and well bonded with the substrate. The composition of the coating is basically the same with target except for the small loss of Al. The main phase of NiCrAlY coating is γ′-Ni₃Al/γ-Ni, with a small amount of β-NiAl phase. During the high temperature oxidation process, a dense Al₂O₃ layer was quickly formed on the surface of NiCrAlY coating, therefore provide good oxidation resistance protection for substrate at 1050 ℃. The failure of the coating should be caused by the continuous growth of cracks in oxide layer and finally exfoliation, resulting in the consumption of antioxidant element.

Key words: NiCrAlY coating, high-temperature oxidation resistance, arc ion plating, superalloy