Preparation method of high corrosion-resistant protective coating on the surface of NdFeB magnet

Abstract

The embodiment of the present invention relates to a preparation method of a high corrosion-resistant protective coating on the surface of a NdFeB magnet. Through the detection and feedback control of plasma characteristic parameters, Al / Al formed by alternate deposition 2 O 3 Multilayer film structure, effectively reducing the micro-defects of the coating, uniform and dense Al 2 O 3 The layer blocks the grain boundaries running through the coating, and achieves a significant improvement in the corrosion resistance of NdFeB magnets; at the same time, it improves the surface hardness of the Al coating, which can effectively prevent the coating from being damaged due to surface scratches. In addition, the method also solves the problems of low deposition rate, difficult structure control and limited coating thickness faced in the existing preparation technology, and ensures the process stability and repeatability in the industrial production process. At the same time, the super corrosion-resistant characteristics can realize long-term use in high-salinity climates, especially for NdFeB permanent magnet materials in offshore wind energy motors, which will bring huge economic and social benefits.

Description

technical field [0001] The invention relates to the technical field of coating preparation, in particular to a method for preparing a high corrosion-resistant protective coating on the surface of an NdFeB magnet. Background technique [0002] NdFeB (NdFeB), as the third-generation rare earth permanent magnet material, is widely used in sunrise industries such as wind power generation, new energy vehicles and energy-saving home appliances because of its excellent magnetic properties and high cost performance. However, since the sintered NdFeB permanent magnet material is a powder metallurgy material with strong chemical activity, its magnet surface is easily corroded and oxidized, which seriously hinders its large-scale application in the industrial field. At present, in order to improve the corrosion resistance of NdFeB magnets, the most commonly used methods are alloying method and surface coating protective layer method. However, the former usually sacrifices the magnetic ...

AI Technical Summary

Problems solved by technology

The reason is mainly because Al 2 o 3 The following problems and deficiencies still exist in the preparation of thin films, specifically: 1. Reactive sputtering of Al 2 o 3 The thin film has a typical target poisoning phenomenon. With the prolongation of the deposition time, the gradually deepened target poisoning state will significantly reduce the energy of the film-forming particles, resulting in a loose and porous film structure, which will adversely affect the corrosion resistance.

2. The reactive sputtering process is difficult to control. In order to ensure the stoichiometric ratio of alumina, the deposition process is mostly in the target poisoning mode of reactive sputtering, and the deposition rate is very low, which cannot meet the needs of industrialization

3. Al 2 o 3 Thin films are inherently brittle materials. The growth difference of thermal expansion coefficient and structure leads to the continuous increase of stress of the film, which is prone to brittle damage or shedding, and it is impossible to realize the preparation of thick films (>5μm) that are conducive to improving corrosion resistance.

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