Protective Coatings/Surface Finish for Neodymium Magnets

A Neodymium magnet does not corrode and will retain its performance theoretically forever in dry environment (if not subjected to excessive heat, radiation or strong external magnetic fields). However, if it is placed in a wet environment, the result may be the opposite. The within-structure Iron can 'rust' and causes a permanent structural change in NdFeB, which will result in a permanent weakening of the magnetic performance – the worst case scenario is a total loss of magnetism.

Therefore, it is recommended to apply a coating on the magnet surface to protect the magnet from moisture (e.g. encasing, modified coatings such as zinc plus rubber, etc). The coating/surface finish should be for best corrosion protection – scratched or damaged surfaced may render the affected region more prone to corrosion. Marine environments (salt sprays, sea water) are particularly corrosive and far from ideal for NdFeB. It is the application and the overall design that determines how well the magnet will perform in damp environments.

Main Coating Types

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