Technical
Coatings and corrosion protection
Sintered NdFeB corrodes if left bare. The coating is chosen for environment, adhesive bonding, and assembly process.
Thicknesses and salt-spray hours are indicative. Test method, exposure duration and acceptance criteria are agreed for the specified coating system; salt-spray hours do not predict service life.
| Coating | Typical thickness | Salt spray (ISO 9227) | Notes |
|---|---|---|---|
| Ni-Cu-Ni | 10 – 20 µm | 24 – 72 h | Default for motor magnets; good mechanical protection; electrically conductive |
| Zinc (Zn) | 5 – 10 µm | 12 – 24 h | Low cost; limited corrosion protection; confirm adhesive compatibility |
| Epoxy | 10 – 20 µm | 48 – 96 h | Good adhesion for bonding; non-conductive; colour options |
| Ni-Cu-Ni + epoxy | 20 – 30 µm | 72 – 120 h | Harsh environments |
| Passivation | < 1 µm | minimal | Only when the magnet is fully potted or encapsulated |
| Parylene / specialty | 5 – 25 µm | application-specific | Medical, vacuum, high-purity |
Specify the coating together with the adhesive and the assembly temperature — an epoxy-coated magnet bonded with a compatible adhesive behaves differently from a nickel-plated one.
Technical references
Updated
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