Effect of vacuum annealing on coercivity and corrosion resistance of Al-coated NdFeB magnets

doi:10.13251/j.issn.0254-6051.2022.06.013

Abstract

Abstract: Al coatings were deposited on the surface of sintered NdFeB by using arc ion plating and then subjected to vacuum annealing. Effect of different annealing processes on microstructure, magnetic properties and corrosion resistance of Al/NdFeB was investigated by means of scanning electron microscopy, permanent magnet material measurement system, electrochemical workstation and salt spray test chamber. The results show that the coercivity first increases and then decreases with the increase of annealing temperature, the highest coercivity of 22.41 kOe is obtained when annealed at 550 ℃ for 1 h, increasing by 7.6%, while the corrosion resistance decreases compared with the untreated magnet. With the increase of annealing time, the coercivity first decreases and then increases. When annealed at 550 ℃ for 5 min, the coercivity is 22.16 kOe, and the self-corrosion current density is 1-2 orders of magnitude lower than that of the matrix NdFeB. The specimens annealed at 550 ℃ for 5 min have higher coercivity and better corrosion resistance.

Key words: Al coating, sintered NdFeB, vacuum annealing, coercivity, corrosion resistance

CLC Number:

TG156.1

Hu Fangqin, Shi Fengkai, Zhang Qingke, Zhao Yu, Xiao Tao. Effect of vacuum annealing on coercivity and corrosion resistance of Al-coated NdFeB magnets[J]. Heat Treatment of Metals, 2022, 47(6): 72-77.

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