Effect of NiCrAlY Coating on Oxidation Resistance of Sm2Co17 Magnets at High Temperatures

Air oxidation behavior of Sm2Co17 magnets coated with magnetron sputtered NiCrAlY coating was studied at 500, 600 and 700 ℃ in terms of variations of mass gains and magnetic prop- erties. Microstructures, chemical composition, and phase constitution of the coating were analyzed by using scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) and X- ray diffraction (XRD). The results show that the NiCrAlY coating can improve the oxidation resis- tance of Sm2Co17magnets in air at 500 and 600 ℃, and its protectiveness declined with the increase of temperature up to 700 ℃. During the oxidation process, the Al atoms moved to the surface and combined with the oxygen atoms to form an oxide film on the surface of NiCrAlY coating, which can effectively maintain the oxidation resistance of NiCrAlY coating.