Surface Treatment of Neodymium Magnet

The sintered neodymium iron boron permanent magnet material is produced by powder metallurgy technology. It is a kind of powder material with very strong chemical activity. There are tiny pores and cavities inside, which are easily corroded and oxidized in the air. The experimental results show that a 1cm³ sintered NdFeB permanent magnet will be completely oxidized and corroded if placed in the air at 150°C for 51 days. After the magnetic material is corroded or damaged, the magnetic properties will be attenuated or even lost over time, which will affect the performance and life of the whole machine, so strict anti-corrosion treatment must be carried out before use.

Zinc Plated

Nickel Plated

Gold Plated

Epoxy Plated

Teflon Plated

Corrosion Resistance of Neodymium Magnets with Different Coatings

Coating TypeProcessing
Methods
ColorThicknessSST (35℃,
5%NaCl)
PCT (85℃,
85%RH)
HAST (120℃,
0.2MPa, 100%RH)
PhosphatePassivationDark Grey1 ~ 3 μm2 hours--
Blue White ZnElectroplatingBright Blue4 ~ 15 μm24 hours--
Color ZnElectroplatingSilver White4 ~ 15 μm48 hours--
NiRack ElectroplatingSilver5 ~ 20 μm16 hours168 hours48 hours
NiBarrel ElectroplatingSilver5 ~ 20 μm48 hours168 hours48 hours
Chemical NiRack Electroless PlatingDark Silver3 ~ 20 μm24 hours168 hours48 hours
Chemical NiBarrel Electroless PlatingDark Silver3 ~ 20 μm72 hours168 hours48 hours
NiCuNiRack ElectroplatingSilver5 ~ 20 μm16 hours168 hours48 hours
NiCuNiBarrel ElectroplatingSilver5 ~ 20 μm48 hours168 hours48 hours
NiSnElectroplatingSilver5 ~ 20 μm72 hours168 hours96 hours
NiAgElectroplatingSilver5 ~ 20 μm72 hours168 hours96 hours
NiAuElectroplatingGolden5 ~ 20 μm72 hours168 hours96 hours
Epoxy ResinElectrophoresisAny12 ~ 20 μm72 hours168 hours96 hours
AlVapour DepositionBright Silver2 ~ 15 μm24 hours168 hours24 hours
Coating TypeProcessing
Methods
ColorThicknessSST (35℃,
5%NaCl)
PhosphatePassivationDark Grey1 ~ 3 μm2 hours
Blue White ZnElectroplatingBright Blue4 ~ 15 μm24 hours
Color ZnElectroplatingSilver White4 ~ 15 μm48 hours
NiRack ElectroplatingSilver5 ~ 20 μm16 hours
NiBarrel ElectroplatingSilver5 ~ 20 μm48 hours
Chemical NiRack Electroless PlatingDark Silver3 ~ 20 μm24 hours
Chemical NiBarrel Electroless PlatingDark Silver3 ~ 20 μm72 hours
NiCuNiRack ElectroplatingSilver5 ~ 20 μm16 hours
NiCuNiBarrel ElectroplatingSilver5 ~ 20 μm48 hours
NiSnElectroplatingSilver5 ~ 20 μm72 hours
NiAgElectroplatingSilver5 ~ 20 μm72 hours
NiAuElectroplatingGolden5 ~ 20 μm72 hours
Epoxy ResinElectrophoresisAny12 ~ 20 μm72 hours
AlVapour DepositionBright Silver2 ~ 15 μm24 hours