How to Choose Rightness Coating of Magnet

Moisture in the atmosphere is potentially enough to cause an uncoated Rare Earth magnet and Neodymium Magnet and NdFeB Magnet to show signs of corrosion . Marine Environmnets are particularly effective at making NdFeB Magnet corrode . The process of corrosion is similar to resting- the structure of the Neodumium Iron Boron magnets changes permanently resulting ina progressive loss in magnetic performance ( the magnet will will weaken, and also breaks down into a powder during the corrosion process).Total magnetic failure is possible due to corrosion . To prevent this , the Magnet is given a coating on this furface finish .

Different coating will has different result to protent the NdFeB magnet. Below is major coating types available for mass production and different properties .

 

Coating materials Indoor Use Abrasion Humidity Water salty Air/ Near Ocean Salt Water Thickness of Coating layer Max work Temperature PCT SST price
Passvation Good Bad Bad Bad Bad Bad 0-02μm lower
 phosphate Good Bad Bad Bad Bad Bad 0-02μm lower
Zinc little Excellent little Excellent little Excellent Bad Bad Bad 8-10μm ≤160℃ >24hr low
Clour Zinc little Excellent little Excellent little Excellent Bad Bad Bad 10-12μm ≤160℃ >48hr low
Ni+Sn Excellent Excellent Bad Bad Bad Bad 10-30μm ≤160℃ >48hr >96hr expensive
Nickel Excellent Excellent Excellent Good Bad Bad 15-30μm ≤200℃ >24hr >48hr Normal
Double Ni( Ni+Cu+Ni) Excellent Excellent Excellent Good Bad Bad 20-30μm ≤200℃ >48hr >72hr normal
Electroless Nickel Excellent Excellent Excellent Good Good Bad 20-30μm ≤200℃ >48hr >96hr Higher
Al Spraying superior superior superior superior superior superior 6-20μm ≤200℃ >48hr >288hr little higher
IVD Al superior superior superior superior superior superior 10-30μm ≤200℃ >48hr >288hr little higher
Epoxy  little superior  little superior  little superior  little superior  little superior  little superior 10-20μm ≤200℃ >48hr  >72hr expensive
Zn +epxoy  little superior  little superior  little superior  little superior  little superior  little superior 15-25μm ≤200℃ >48hr  >96hr High expensive
NiCu +epxoy Superior Superior Superior Superior Superior Superior 15-30μm ≤200℃ >48hr  >108hr higher expensive
Zintek  Very superior  Very superior  Very superior  Very superior  Very superior  Very superior 10-30μm ≤200℃ >200Hr  >800hr normal
Zintek+epoxy ultimate superior ultimate superior ultimate superior ultimate superior ultimate superior ultimate superior 20-30μm ≤200℃ >200Hr  >1500hr little expensive
Plastic/Rubber Superior Superior Superior Superior Superior Superior 250-500μm ≤200℃ medium

 

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