Samarium Cobalt, Alnico, and Ceramic materials are corrosion resistant and do not require to be coated against corrosion. Alnico is easily plated for cosmetic qualities and Ceramics may be coated to seal the surface which will otherwise be covered by a thin film of ferrite powder.
NdFeB magnets, both sintered and bonded, are susceptible to corrosion and consideration should be given to the operating environment to determine if coating is necessary. Nickel or tin plating may be used for NdFeB magnets, however, the material must be properly prepared and the plating process properly controlled for successful plating.
Aluminum Chromate or Cadmium Chromate vacuum deposition (PVD) is a successful process that can provide a coating thickness as low as 0.0003”. Teflon, Parylene, various epoxies and other organic coatings are relatively inexpensive and are also successful as NdFeB coatings. A further option for critical applications is to apply two types of protective coatings or to encase the magnet in a stainless steel or other housing to reduce the chances of corrosion.
The effectiveness of coatings on customer’s parts can be tested in Magnet Applications Temperature and Humidity Controlled Environmental Chamber. For further information please contact our sales team.