The neodymium alloy is composed of iron and neodymium components in the crystalline structure. Hence they are highly liable to corrosion and oxidation. If it is kept in the presence of water, acid or alkali etch, then the magnet is likely to demagnetize and rust. It must be stored in a hermetically stored system to increase its longevity. However, the magnet will never corrode if kept in the presence of adhesives and organic solvents.
If you do not follow the proper and systematic pre-process, then the magnet might corrode from inside out. Many manufacturers coat the magnet with nickel copper nickel plating to prevent rusting. However, this is not a successful and recommended preventative technique. It often fails to offer complete protection against rusting in many industries.
Learn About the Fully Dense Magnets
The fully dense neodymium iron boron magnets also available in the market. They are prepared from powdered metal process. However, the quality of powder used in the manufacturing process will affect environmental tolerance level and magnetic performance of the magnet.
If the manufacturers use well-formed and appropriately sized grains, then it will result in the well performing magnets. Even such magnets will have some concentration of un-reacted components that might oxidize with time.
The NdFeB is a highly reactive alloy, and hence you must choose the plating or coating carefully. None of the neo magnets are coated considering some specifications, ASM, ASTM etc. However, you can evaluate the performance of any plating using a salt fog test or salt spray test. The magnet geometry and corrosion inhibiting layer is helpful to increase the operational life of magnets.
The neodymium magnets, which are not coated, will fail the salt fog test. However, the test can only evaluate the performance of plating and not the quality of alloy. There are many other humidity tests and elevated temperature tests to evaluate the bare neo alloy.
You could also determine the quality of substance by checking the effective volume loss. Measure the effective mass of the alloy before and after the environment test. If any portion of the alloy reacts during the environmental testing exposure, then it will be corroded and removed from sample.
To be on the safer side, you must encapsulate all the neodymium magnets that are used in commercial applications. You can even call a trustworthy, efficient and experienced magnet application specialist. The expert will suggest good tips to extend the operational life of the magnet.
How to Make the Right Decision
Many of you might not know where to buy neodymium magnets from. While purchasing it, check that the magnet does not include any epoxy or plastic binder. The magnets that include epoxy binders are compression molded and are isotropic in nature.
You must evaluate a magnet on different parameters before placing the order. You can consult the representatives of different companies and learn the quality of magnets they supply. You could tell them the purpose of usage, so that they can recommend the ideal rare earth magnet to satisfy the requirement.