Cast Alnico Magnet resources
Alnico Magnets do not usually require a protective coating or surface finish to prevent corrosion, they have a certain of abilities to protect themselves from some corrosion. The corrosion resistance offered actually depends on the chemicals it is exposed to and the grades the magnet belong to. But as you know, Alnico contain some free iron, so that they can be prone to surface corrosion with water or some wet environment.
But they are very excellent for corrosion resistance when used in motor oil, petrol,alcohol and organic solvents… for some special applications, you also can choose coating, Ni, Cu, or Ni+Sn are popular coating options as we know. And Alnico magnet are also widely be painted，that can make the magnet more aesthetically pleasing, and give a protective coating. it is another much popular method. The painting color usually Red, or Black, Blue, one different pole usually use different color. If you see a magnet, that blue in north, red in south, it must be the Alnico magnet.