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Choose Neodymium Iron Boron magnets or not?

by Stanford Magnets

Over the last 10 years,the rare earth magnets which one of permanent magnets have become extremely popular in almost all high technology applications that require high performance magnets. Motors, sensors, computers, and microwave components are a few areas where Neodymium Iron Boron magnets are successfully used . The recent "miniaturization" of electronic and mechanical components is due to the high-energy products that are achieved using Neodymium Iron Boron magnets. Large capacity hard drives, miniature hand held tape recorders, feather weight head sets, and anti-lock braking systems  have made tremendous leaps due to the Neodymium magnets.

The selection of permanent magnets in your applications will depend on your working environment. If you use the magnets at elevated temperatures, select the alloys that have a high intrinsic coercivity (Hci). If you use the alloy at lower temperatures (such as room temperature), you may select higher Br materials. Remember that if the magnet is being used in adverse conditions, such as repelling positions in motors where repelling magnetic fields are being used to drive the rotor and similar applications, selecting materials with moderate or high coercivity is recommended. Applications where fields are being used to trigger sensors, switches, and similar applications may use lower coercivity magnets.

Using the permanent magnets in cryogenic temperatures (below 200°C) is not recommended from our standard alloys; These custom alloys are available in limited quantities since they are extremely specialized and only produced in the lab. These advanced alloys can reach energy products in excess of 53 MGOe at cryogenic temperatures. The Neodymium Iron Boron magnets are prone to rapid oxidation, salt spray, salt water, and hydrogen are very harsh on the magnet. Consider hermetically sealing the magnet if you wish to use NdFeB in such environments.

Do NOT use permanent magnets under the following conditions:

In an acidic, alkaline, or organic solvent (unless you are going to hermetically seal the magnet inside a can)
In water or oil (unless hermetically sealed, or you are prepared to accept a limited life)
In an electrically conductive liquid, such as electrolyte containing water
In a hydrogen-containing atmosphere, especially at elevated temperatures. Hydrogenation, a process where the Hydrogen molecule will react with the NdFeB, will occur, causing the magnet to rapidly deteriorate
Environments containing corrosive gasses, such as Cl, NH3, Nox, etc.
In the path of radioactive rays.

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