Surface protection and surface coating for the permanent magnet
1) Surface protection: Under the normal atmospheric condition(room temp. humidity 50%),it is unnecessary for special surface protection to the permanent magnet. However, for many applications, the surface protection is a must. This is for the following reasons:
Anticorruption protection: The rare earth permanent magnet exposed to acid, alkaline solution,salt,cooling lubricant or deleterious gas is usually protected by a surface coating. For NdFeB material, it is easy to erode by high humidity or dew.
Protection from magnetic granules:rare earth permanent magnet is a sintered magnet,so the magnetic granules on the surface are unavoidable. For some applications, for example the hard disc machine or sound coil system, the soft magnetic granules will influence the function,even damage the magnetism system. The surface protection coating could protect the permanent magnet from extra accumulation and keep its surface clean thoroughly.
Operation protection: In a certain system, the permanent magnet is usually installed by mechanical pressure. Under some conditions, the pressure install process will cause smashes. The sharp brim is insecure. So we should consider the coating for every application. We suggest the user to choose the most appropriate coating for their application.
3) Types of the protection coating:©There are two basis coatings, metal coating and organic coating. To meet special requirement of the user, we could also adopt metal/metal,metal/organic double-coating and many other special coatings.
Metal coating: Usually, the metal coating is made by electrical plating technique. In addition to standard Nickel-plating and Zn-plating, other coating is also available, if the user require.
Organic coating:The basic organic coating is epoxy. Lacquer spraying is also adoptable.
Temporary anti-corruption coating/surface passivation:For the protection in transit or storage period, this temporary coating is usually used.