Coatings
Coatings and Surface Treatment
Sintered NdFeB rusts if you skip the jacket. Ni-Cu-Ni is the default stack.
Sintered NdFeB is porous and chemically active. The original coating article states that an uncoated 1 cm³ sample oxidizes completely in air at 150°C in 51 days. Coating is not cosmetic.
Pretreatment described on the source page: grind and chamfer, chemical degrease, pickle oxide, weak-acid activate, with ultrasonic cleaning between steps. Dirty pretreatment shows up later as blistering or peel.
Finishes Ando names:
- Zinc — lowest cost of the ranked options; softer and less corrosion-resistant
- Ni-Cu-Ni — the most common stack; brighter and harder than zinc
- Nickel + copper + electroless nickel
- Epoxy — highest price of the three they rank on that page
Tin, precious-metal and electrophoresis / passivation appear as additional mentions. Only zinc and nickel plate directly onto NdFeB; other stacks start from nickel. Name the coating on the RFQ the same way you name the grade.