Preparation method of sintered nd-fe-b magnet surface protective coating

Abstract

The invention discloses a preparation method of a sintered nd-fe-b magnet surface protective coating. According to the method, the furnace pre-treatment is carried out on a magnet by adopting circulating argon ion bombardment and main arc bombardment, then, the magnetic control sputtering mode is carried out on the surface of a base body to prepare a layer of a metal film with relative low hardness and the electrochemical activity being higher than that of the iron element for bottoming, the bottoming thin film is further bombarded and compacted by adopting the main arc bombardment mode to ensure that the thin film and the base body is tightly combined, and a layer of diamond-like thin film is prepared on the surface of the bottoming layer by adopting a vacuum evaporation ion beam assisteddeposition technology; after the composite thin film is deposited and discharged out of the furnace, the composite coating is further mechanically compacted by adopting a shot blasting process, and the prepared bottoming metal / the diamond-like composite coating has high hardness and also has excellent wear resistance and corrosion resistance, and meanwhile, the binding force between the composite coating and the base body is extremely high by adopting the scheme and the method; and the preparation of high-hardness, high-binding force and corrosion-resistant coating on the surface of the sintered nd-fe-b magnet can be realized.

Description

technical field [0001] The invention relates to a method for preparing a protective coating on the surface of a sintered NdFeB magnet, belonging to the technical field of magnetic material surface protection. Background technique [0002] In recent years, although the magnetic performance of sintered NdFeB magnets manufactured in my country has been comparable to that of Japan and European and American powers, there is still a big gap in the corrosion resistance of the prepared magnets. The sintered NdFeB magnet has a multi-phase composite structure, and the potential difference between the phases inside the magnet is relatively large, especially the Nd-rich phase at the intersection of grains and grain boundaries has a high electrochemical activity, which is extremely high in electrochemical, humid or high-temperature environments. It is easy to preferentially corrode, which will lead to the occurrence of electrochemical corrosion inside the magnet, and finally lead to the ...

AI Technical Summary

Problems solved by technology

[0004] However, the physical vapor deposition film currently used for magnet surface protection is mainly Al film. Al film deposition has many advantages such as simple process, easy operation, low cost, etc., and the film has high electrochemical activity, which can provide the substrate to a certain extent. Sacrificial anode protection, but because the electrochemical activity of the Nd-rich phase inside the sintered NdFeB matrix is ​​higher than that of Al, the effect of this sacrificial anode protection is greatly reduced

And because the hardness of the Al film is low, it is a soft metal film, and the wear resistance of the film is extremely poor. It is easy to cause the coating to break during the packaging and transportation process and cause the coating protection to fail.