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neodymium magnet surface coating
Time:03/11/2022
NdFeB magnets generally need to be electroplated to prevent corrosion due to their poor corrosion resistance. So what is the best effect on the magnet surface? First, let's understand what can be plated on the surface of the NdFeB magnet.
Gold-plated NdFeB magnetic ring
The coatings of NdFeB magnets are generally nickel, copper, chromium, gold, black zinc, blue and white zinc, epoxy resin and so on. The color of the magnet surface varies depending on the electroplating, and the storage time also varies.
After comparative study of the effects of NI, ZN, epoxy resin, and PARYLENE-C coatings on the magnetic properties of NdFeB magnets in three solutions, we found that: in acid, alkali, and salt environments, polymer material coatings The protection effect of magnet is the best, epoxy resin is relatively poor, NI coating is second, and ZN coating is relatively poor.
Zinc: The surface looks silvery white. It can be used for 12-48 hours of salt spray, and it can be bonded with some glue (such as AB glue). If it is electroplated, it can be stored for 2 to 5 years.
Nickel: It looks like the color of stainless steel, the surface is difficult to be oxidized when left in the air, and the appearance is good, and the gloss is good. The electroplating can pass the salt spray test for 12 to 72 hours. The disadvantage is that it cannot be used for bonding with some glue, which will cause the coating to fall off and accelerate the oxidation. Nowadays, the nickel-copper-nickel electroplating method is mostly used in the market, and the salt spray is used for 120-200 hours.
Copper: It mostly appears in the hardware industry. Few people in the NdFeB magnetic material industry use it, and its appearance is yellow.
Chromium: Chromium electroplating industry is also relatively rare, and its electroplating cost is very high, and the average company cannot accept it. However, it has a strong ability to release corrosion, and it is difficult to react with other substances. Mainly used in places with strong pH.
Black zinc: According to customer requirements, the surface of NdFeB magnetic products can be treated to black. In terms of electroplating process, a black protective film is added through chemical treatment on the basis of galvanizing. This film can also protect the product. Use it to increase the salt spray time and prolong the oxidation time. But its surface is easily scratched and loses its protective effect. Few people use it now, most of which are replaced by resin.
Jin: The yellow gold jewelry of some stalls we saw on the street was mostly gilded or copper. Gold-plating makes the product look very beautiful like gold. It is generally used in the jewelry industry. Our products can also be gold-plated for magnetic jewelry.
Epoxy resin: After the product is nickel-plated, a layer of resin paint is added to the outside. This industry has only had a market in the past two years, and its development speed is very fast. Nowadays, many people use various electroplating products. You can do the color you want.
When choosing what material to use for coating, the appropriate coating should be selected according to different use environments. The coatings of different manufacturers are different, and the main reason is the length of chamfering and electroplating time. Without understanding the electroplating of the magnet, how should we judge the quality of the coating? In fact, one of the easiest and quickest ways is to look at the coating. The brighter the coating, the better the quality.