In This Guide
Why NdFeB Magnets Need Coatings
NdFeB magnets are composed of iron-rich phases that are highly susceptible to oxidation and corrosion. Without protection, a bare NdFeB magnet will develop surface rust within hours in humid conditions. The Nd-rich grain boundary phase is especially vulnerable.
Nickel (NiCuNi) — The Standard
A three-layer electroplated coating that provides the best combination of corrosion resistance, appearance, and cost. The copper intermediate layer provides a ductile barrier and improves adhesion between the nickel layers.
- •Thickness: 10–25 μm total
- •Salt spray: 48–72 hours (ASTM B117)
- •Appearance: Bright, metallic silver
- •Best for: Most industrial and consumer applications
Zinc — Budget Option
Lower cost than nickel but with reduced corrosion resistance. Available in clear, blue, and yellow chromate finishes. Suitable for indoor applications or as a base layer.
- •Thickness: 8–20 μm
- •Salt spray: 24–48 hours
- •Appearance: Dull silver to blue-chromate
- •Best for: Cost-sensitive indoor applications
Epoxy — Maximum Protection
Applied by electrophoretic deposition (e-coating) for uniform coverage including inside blind holes and recesses. Excellent for humid and mildly corrosive environments.
- •Thickness: 15–30 μm
- •Salt spray: 200+ hours
- •Appearance: Black, smooth matte finish
- •Best for: Outdoor, automotive, marine environments
Specialty Coatings
For demanding applications, we offer Parylene (medical/aerospace — pinhole-free), PTFE/Teflon (food processing — FDA compliant), gold plating (electronics — bondable), and rubber coating (consumer products — shatter protection).
Pro Tip: Not sure which coating? Send us your operating environment details and we'll recommend the most cost-effective solution.
Request coated sample magnets to evaluate in your environment before committing to production.
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