Design Guide
Coatings
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 (although
not a problem for most applications).
Neodymium
Iron Boron magnets 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 Neodymium Iron Boron magnets,
however, the material must be properly prepared and
the plating process properly controlled for successful
plating. Plating houses experienced in the plating of
NdFeB materials are difficult to locate, and must be
furnished with the necessary information for proper
preparation and control of the process. Aluminum chromate
or cadmium chromate vacuum deposition has been successfully
tested, with coating thickness as low as 0.0005".
Teflon and other organic coatings are relatively inexpensive
and have also been successfully tested. 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.
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