Permanent magnet materials contain iron elements, iron shows the most significant ferromagnetic properties of all elements, which is why it exists in the most powerful magnets. However, iron is highly reactive to water, making magnets with a high iron content very susceptible to corrosion.
Other ferromagnetic elements used in different types of permanent magnets include nickel, cobalt, gadolinium, and dysprosium, all of which have an effect on magnetic strength and corrosion resistance.
There are many factors to consider when exploring custom magnetic components, and corrosion resistance is one of the key ones to consider.
Firstly,Currently the strongest commercial permanent magnet on the market is Ndfeb magnets, but because of their high iron content, they are also extremely perishable in wet environments, so almost always coated before use.
Secondly,Samarium cobalt magnets, like Ndfeb magnets, belong to the rare earth family and are more resistant to corrosion even when uncoated. This is because most of the iron used in neodymium magnets is replaced by cobalt, which does not react with water, so samarium cobalt magnets are widely used in offshore operations.You may find that some samarium cobalt magnets will have a coating, mainly for aesthetic purposes or for application-specific reasons, such as adhesion or sterility.
Thirdly,Both aluminum-nickel-cobalt magnets and ferrite magnets are known for their corrosion resistance, although they do not have the same magnetic level as rare-earth samarium cobalt magnets and Ndfeb magnets.Some grades of aluminum-nickel-cobalt magnets do contain trace amounts of iron, so some slight surface corrosion will occur over time if exposed to water. However, nickel-cobalt alloys perform very well when exposed to other lubricants, such as oils, solvents or alcohol.
Fourthly,Ferrite magnets are made of iron oxide, so they do not corrode even when submerged in water.Because of their unparalleled corrosion resistance, ferrite magnets are rarely coated, but because ferrite is a dusty material, some applications require some surface treatment to avoid dust diffusion.