Treatment Method of NdFeB Magnet After Oxidation and Surface Coating Treatment Process

Ⅰ. What are the treatment methods of NdFeB magnets after oxidation?

1. Electroplating

Electroplating is mainly nickel plating and zinc plating. Nickel plating is divided into single nickel, double nickel, nickel-copper-nickel, etc. according to the plating structure; according to the appearance and color, it is divided into dark nickel, semi-bright nickel and light nickel. The layers are mostly bright nickel and semi-bright nickel. The advantage of nickel plating is that the coating is more wear resistant and more resistant to the environment, and what's worse, the nickel layer is a ferromagnetic substance. The magnet has a certain influence on the magnetic performance, which is especially obvious for thin and small products. The improvement method is to use part of the copper layer instead.

2. Conversion coating

NdFeB conversion coating mainly includes phosphating film and passivation film. Since the conversion coating is a protective film in the manufacturing process, many products will have flash rust after long-term use.

3. Coating

The coating mentioned here refers to the coating carried out by methods such as electrocoating, spraying, brushing and dipping, excluding gas phase coating. Epoxy coatings vary in salt spray resistance, hardness, and color due to different types of coatings. Vapor phase coating includes PVD method and CVD method, which stand for physical vapor deposition and chemical deposition respectively.

Ⅱ. What is the treatment process of the surface coating of NdFeB magnets?

NdFeB permanent magnet material is a highly active powder metallurgy material, which is prone to corrosion. Therefore, when performing surface treatment, appropriate pretreatment and electroplating processes should be carefully selected. Sintered NdFeB permanent magnet materials must go through chamfering, degreasing, pickling, ultrasonic cleaning and other processes that can stabilize and clean the surface before electroplating, so as to obtain a coating with good bonding, low porosity and long-lasting corrosion resistance.

The main components of NdFeB are neodymium and iron, which are easy to rust. Therefore, NdFeB magnets must be surface-coated. Surface chemical passivation is one of the best solutions at present.

We have advanced epoxy technology, which can meet the salt spray test for 500-1000 hours. NdFeB has extremely high magnetic energy product and coercive force, and at the same time has the advantages of high energy density, high cost performance, and good mechanical properties; the disadvantages are low magnetic transition point, poor temperature characteristics, and easy powder corrosion, which must be adjusted Its chemical composition and surface treatment methods can be improved to meet the requirements of practical applications.

After water is treated with neodymium, iron, and boron, the angle and length of water molecular bonds change simultaneously. The hydrogen bond angle is reduced from 105° to about 103°, which causes a series of changes in the physical and chemical properties of water, greatly improves the active solubility of water, and the calcium carbonate and carbonate in the water are decomposed during the cooking process to form softer calcium bicarbonate and carbonate. Magnesium Hydrogen. They are not easy to accumulate on the wall, and are easily taken away by water. In addition, the degree of polymerization of water increases, and the dissolved solid becomes finer particles. After the particles are refined, the distance between two ions decreases, and the binding force becomes larger. It is not easy to condense on the wall, so as to achieve the effect of descaling.

When choosing an electroplating process, it is necessary to consider the protection and production practicability of the process, and also pay attention to the impact and damage caused by electroplating emissions to the environment.

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