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Category: Intended Use

Magnet Coatings

Do all grades of Nd-Fe-B (Neodymium) material still need to be coated/plated?

Neodymium magnets will rust because they contain iron and other reactive materials, and so generally need a coating to protect from exposure. The most common type of plating for neodymium magnets is Nickel (Ni-Cu-Ni), and is excellent for general indoor use. It handles normal wear and tear very well.

Oxidization (rust)

A magnet that is exposed to air will oxidize. If, for example, it’s a chip to the coating, that area will rust, and the remainder of the magnet will maintain its integrity. A spot of oxidization will not result in complete degradation of the magnet, just the oxidized area will lose its strength, so don’t throw the magnet out. Please note that a chipped magnet can lose some structural integrity and become more susceptible to breakage. With oxidation, the magnet will weaken and even breaks down into a powder during the corrosion process.

Different coatings display different tolerances to chemicals, salt air, humidity, and abrasion. Below is a table that highlights the different advantages and disadvantages.

Magnet coating and structural integrity

As a whole, a magnet substrate is brittle because magnets are generally a highly compressed power. Coatings tend to improve a magnet’s strength, and will help with resistance to chipping and wear, particularly around corners. The easiest and most common way (by far) to chip/break a magnet is when they slap together, so handle them carefully.

What surface coatings are available?

There are approx. 50 different coating options available in the market that range from refrigerator magnets to coatings for satellite applications, medical uses and even used inside the body.

Since the vast majority of these are so specialized, we do not carry them in stock, but coating such as epoxy, gold, silver, titanium, rubber, or aluminum can be custom ordered via this web form.

In stock, we carry:

Nickel-Copper-Nickel (Ni-Cu-Ni)
Zinc (Zn)
Parylene C

Table of surface coatings with typical usage scenarios

Coating Indoor Wear Humidity/Water Chemicals FDA Approved
Nickel (Ni-Cu-Ni) Ideal Suitable Inappropriate Inappropriate No
Zinc (Zn) Suitable Ideal Ideal Inappropriate No
Parylene Suitable Ideal Ideal Ideal Yes
Epoxy (Ni-Cu-Be) Suitable Inappropriate Ideal Ideal No
Gold/Silver Suitable Suitable Ideal Ideal No

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