Common methods of surface treatment of NdFeB magnets

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NdFeB permanent magnet is also known as strong magnet, because of its strong magnetic properties and cost performance, it is widely used in various fields. We all have automatic surface coating treatment for NdFeB products before use. The magnet manufacturer will take you to know the most common ways of external surface treatment for NdFeB.
1. Neodymium iron boron magnet degreasing: alkaline degreasing agent, emulsifier and organic degreasing agent have little corrosiveness to neodymium iron boron, and they are easy to rust after being washed with degreasing water, forming a yellow rust film.
2. NdFeB magnet passivation: the production process of NdFeB is different from that of stainless steel. It is mainly composed of powder making, bonding and sintering. The intergranular structure of NdFeB, iron and boron is not compact. Strong oxidizing acid passivation solution will only increase corrosion. Alkaline passivation solution is used for iron-based products (including stainless steel passivation, with relatively general effect).
The general alkaline passivation solution used for NdFeB still has a temporary anti rust effect, and the effect may be better after closing treatment. The alkaline passivation treatment can not do without oil removal, water washing, acid pickling, water washing, passivation and water washing, and it can be closed or even cleaned with alcohol, so the labor time and cost are relatively large; phosphating used for NdFeB surface treatment can only have a temporary anti rust effect Fruit, technology miscellaneous.
3. Sealing treatment of NdFeB magnet: the sealing treatment of NdFeB magnet is usually carried out before electroplating or electroless plating. In some cases, bubbles will appear in NdFeB spray paint. In this case, sealing treatment is also required.
4. Neodymium iron boric acid washing:

NdFeB is easy to oxidize and absorb moisture. Shortening the treatment steps can reduce the loss of NdFeB. The larger corrosion link of NdFeB is produced in the pickling process. Compared with dilute nitric acid + corrosion inhibitor, the pickling time is short. Because dilute nitric acid is oxidizing, it is easy to cause NdFeB to be oxidized, and the dilute nitric acid quickly turns from colorless to yellow, mainly composed of neodymium and iron compounds If the washing time is too long, the surface area is gray and not easy to clean. After pickling, the surface is in an activated state, which is easier to rust.

1 200525104642327 - Common methods of surface treatment of NdFeB magnets

Nd-Fe-B four in one treatment:
Based on the analysis of neodymium, iron and manufacturing process, the four in one process of oil removal, rust removal, passivation, rust prevention and hole sealing is developed. At room temperature (30-40 ℃, better), the ultrasonic wave is used to cooperate with the four in one treatment solution of neodymium, iron and boron for cleaning. The cleaning time is generally about 10 minutes. The four in one treatment is very suitable for neodymium, iron and boron products with less surface grease and only floating rust (not rust spots), and the effect is better than that of phosphorus After treatment: electroplating, electroless plating, electrostatic spraying, epoxy resin.
Neodymium iron boron four in one surface treatment is aimed at developing simple and effective pretreatment. The more neodymium iron boron treatment process, the greater the loss.
The above content is about the four ways of NdFeB surface treatment technology, the content is from the NdFeB magnet factory.

Previous Color of NdFeB and ferrite magnets before machining
Next Comparison of injection molding and press molding processes of bonded NdFeB
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