Vacuum aluminizing method of surface of neodymium-iron-boron permanent magnet

Abstract

The invention relates to a vacuum aluminizing method of the surface of a neodymium-iron-boron permanent magnet. The method sequentially comprises the following steps of: (1) polishing and cleaning the surface of the neodymium-iron-boron permanent magnet by adopting a wet method; (2) putting the neodymium-iron-boron permanent magnet on a rotating workpiece fame in a film plating chamber to ensure that the temperature of the neodymium-iron-boron permanent magnet is kept between 250 DEG C and 300 DEG C; (3) starting a vacuum pump on the film plating chamber and adjusting the vacuum degree of the film plating chamber to be 1-9*10<-3>Pa; (4) meanwhile, starting multi-arc cathode evaporators at both sides of the film plating chamber, a plane magnetic sputtering target and the rotating workpiece frame to carry out magnetic control multi-arc sputtering for 2-7 hours; (5) maintaining the film plating chamber to be cooled for 30-60 minutes under vacuum, aerating, opening the chamber, taking out the aluminized neodymium-iron-boron permanent magnet and carrying out passivation with a non-chrome passivation solution. High energy ions generated by magnetron sputtering strike low-energy ions generated by the multi-arc method so as to promote the low-energy ions to generate more ionization, wherein the speeds and the trends of the high-energy ions and the low-energy ions are uniform, thus the efficiency is improved.

Description

technical field [0001] The invention relates to a metal surface plating method with aluminum, in particular to a vacuum aluminum plating method on the surface of a neodymium-iron-boron permanent magnet. Background technique [0002] The new permanent magnet material NdFeB is the third-generation rare earth material that appeared in 1983. Usually, NdFeB is composed of rich Nd and base phase Nd 2 Fe 14 Composed of phase B, in order to obtain excellent magnetic properties, this composite metallographic structure is necessary. However, it is this complex phase structure that is detrimental to the oxidation resistance of the magnet. The different phases in contact with each other form a "battery" due to the difference in electromotive force, the Nd-rich phase is the anode, and the base phase is the cathode. Nd is very easy to oxidize, and the rich Nd with a very small volume is accelerated to corrode under the action of a relatively large anodic current, and this corrosion pro...

AI Technical Summary

Problems solved by technology

[0006] Magnetron sputtering, this kind of vacuum plating has the advantages of dense aluminum coating, good adhesion, and relatively slow deposition speed, but when the film thickness is greater than 5 microns, due to too much internal stress, the coating will fall off, chipping, etc. Phenomenon, so that the post-treatment process of aluminum plating cannot be carried out

However, when the film thickness is less than 5 microns, the corrosion resistance of the coating will be greatly reduced, which cannot meet the requirements of actual working conditions and has no practical value.