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Will samarium cobalt rare earth magnet rust without coating?

The Neodymium magnet we have seen has a coating on its surface, while samarium cobalt usually has no coating. A netizen asked, will samarium cobalt rust without a coating? Need to add electroplating protection? What are the benefits?

So let me answer these questions for you!

  • Will samarium cobalt magnets rust?

Not easy to rust but can rust, because the composition of samarium cobalt magnets in addition to samarium and cobalt, there are other components, which contain iron components, so samarium cobalt magnets will also cause rust because of the presence of iron this component. However, the iron content of samarium cobalt is lower than the iron content of NdFeb, so the rust phenomenon will not be very serious. For example, if the samarium cobalt magnet is used in seawater, some rust spots will occur on the surface of the product after a long time, but it will not affect the performance and use of the magnet.

  • Does samarium cobalt magnet need electroplating?

A small number of samarium cobalt magnets need to be electroplated. Although it is rare to see samarium cobalt electroplating, in fact, some samarium cobalt must be electroplated to ensure performance stability due to the use of the environment.

High temperature motor samarium cobalt arc magnet picture

High temperature motor samarium cobalt arc magnet picture

  • Why should samarium cobalt magnets be electroplated?

Samarium in the sintered samarium cobalt permanent magnet is quite stable in dry air, cobalt does not react with water at room temperature, it is also very stable in humid air, cobalt has strong corrosion resistance, and the new phase formed by the two is also quite stable, in the dry, wet and high temperature environment has a strong oxygen resistance, chemical and corrosion resistance, so at room temperature sintered samarium cobalt permanent magnet does not need surface protection, However, under high temperature conditions (temperature ≥400°C), samarium cobalt magnets are prone to samarium desamarization, resulting in magnetic attenuation of the magnet, which requires necessary surface protection.

  • What are the advantages of samarium cobalt Rare-earth magnet coating?

From the above we know that samarium cobalt magnets can be electroplated, such as nickel plating, zinc, nickel copper nickel, epoxy and so on. So why electroplating? Doesn't plating add some extra cost? In fact, samarium cobalt magnet electroplating has three advantages.

1. Look good. Electroplated samarium cobalt magnets look less powdery, so they look much better.

2. Prevent rust. Although the anti-rust ability of samarium cobalt magnet is still relatively strong, but electroplating will be better.

3. Shatterproof. Samarium cobalt magnets are still relatively easy to break, and electroplating can effectively solve the fragile problem.

Of course, electroplating is a kind of processing, which will increase some processing costs, so choose whether to deposit according to product demand.

The above text is organized and shared by the magnet manufacturer Courage Daisy for you. I believe that after reading it, you will understand why samarium cobalt magnets will rust and why they also need to be electroplated.

If you have any requirment about samarium cobalt magnets, please contact us and provide your demand!

Related technical articles;

Rare Earth Neodymium Magnets vs Samarium Cobalt Magnets

Composition and proportion of samarium cobalt magnets

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