Rare earth permanent magnet, Rare Earth magnet, Neo, NdFeB, SmCo

Rare Earth Permanent Magnets, NdFeB Magnets and SmCo Magnets

Rare earth permanent magnets include SmCo magnets (Samarium-Cobalt) and NdFeB magnets (Neodymium-Iron-Boron).
SmCo magnets were developed in the 1970's and were once the most powerful permanent magnet. They have a very strong magnetic field and tend to resist demagnetization extremely well. These magnets are also very corrosion resistant and can operate at higher temperatures up to 300°C. They are widely used in applications in which higher operating temperature and higher corrosion and oxidation resistance are crucial. The temperature coefficient of remanence is usually less than ±0.05%.

Neodymium Iron Boron
(NdFeB) magnet

Samarium Cobalt
(SmCo) Magnet

NdFeB magnets are developed in the 1980's with excellent magnetic characteristics (high energy product and high coercive force etc.) and relatively low cost. These magnets are getting to replace the traditional magnets of hard ferrite, AlNiCo and SmCo in many fields such as electro-accoustic devices, electric motors, sensors/transducers, instruments and meters, auto industry, petro-chemical industry and magnetic health-care products etc.

NdFeB magnets have a higher Maximum Energy Product, (BH)max, than SmCo magnets. (BH)max of NdFeB can easily reach 30 MGOe and even goes up to 48 MGOe. The temperature stability of NdFeB is not as good as SmCo magnets. Magnetic performance of NdFeB magnets will deteriorate rapidly above 180°C. Compared to SmCo magnets, the corrosion and oxidation resistance of NdFeB is relatively low. Therefore, A surface coating is usually applied on NdFeB magnets. Zinc or nickel coating is common used as a protective layer.

Further Information On Permanent Magnets

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