Neodymium reacts to oxygen and oxidises quickly if untreated. That's why all neodymium magnets in our shop are covered with a protective coating, which is so thin that it doesn't have any impact on the adhesive force of the magnet.
We use the following coatings on our neodymium magnets:
Nickel (Ni-Cu-Ni)
By far the most frequently used coating;
Colour: shiny metallic;
Good price/performance ratio;
Thickness: approx. 12 micro metres.
Gold-coating (Ni-Cu-Ni-Au)
Razor-thin coating (24k) over normal Ni-Cu-Ni coat, but with the same features;
Colour: shiny metallic;
Thickness of gold-coating without Ni-Cu-Ni: 0,05 micro metre;
Thickness of whole coating: approx. 12 micro metres;
The gold-coating rubs off easily with frequent use. It is therefore suitable for decorative purposes only, not for playing or working.
Chrome (Ni-Cu-Ni-Cr)
Better resistance against rubbing and pressure (that's why we use this coating for our sphere magnets)
Colour: dull, grey-metallic
Thickness: approx. 15 micro metres
Copper (Ni-Cu)
Colour: shiny brown-red-gold. The colour may change over time due to oxidation (darkening, spots)!
Slightly weaker rubbing and impact resistance than Ni-Cu-Ni
Slightly weaker corrosion resistance than als Ni-Cu-Ni
Thickness: approx. 10 micro metres
Epoxy resin (Ni-Cu-Ni-Epoxy)
Colour: black
almost 100% non-corrosive, as long as coating is intact
not shock-resistant (crumbles quickly)
Thickness: approx. 10 micrometre
Even the smallest, not visible to the eye, damages of the coating will cause damage to the magnet in the long term when exposed to moisture.
Teflon (PTFE)
0.08'' thickness or more; White Color.
The raw materials of Teflon is from DuPont and approved by the test (FDA method) of Daikin industries.
Good chemical stability and corrosion resistance, frequently used dental and medical applications
Rubber/Plastic
0.04'' thickness; various color
highly corrosion resistant, increase friction
Othert neodymium magnets coatings we offer:
Stanford Magnets has been providing various neodymium magnets coatings for over 10 years.