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HOME : PRODUCTS : PERM MAGNETS : SAMARIUM COBALT
SAMARIUM COBALT MAGNETS
Sintered samarium cobalt (SmCo) magnets, available since the early 1970's, offer the designer a tremendous combination of extremely high magnetic properties, outstanding thermal stability and excellent corrosion resistance. These characteristics make SmCo the ideal material in applications such as servo-motors, pump couplings, and sensors, particularly where the magnet is required to operate at high temperatures, across a broad temperature range or in a corrosive environment.
The first alloy composition was SmCo5 with maximum energy products of about 18 MGOe (140 kJ/m3). Shortly after this development, an additional alloy composition, Sm2Co17 was developed by Karl Strnat. This was developed over time to provide over 30 MGOe (240 kJ/m3). Although processing of the 2-17 composition is more difficult, it also has the advantage of containing less Cobalt than the 1-5 composition. Raw material costs are lower. 2-17 is also very corrosion resistant and more stable at very high temperatures. Both types are manufactured by Precision Magnetics to satisfy specific customer needs.
MAXIMUM USE TEMPERATURE
Although the Curie temperature for SmCo materials is between 700 and 800 degrees, current alloy compositions can only be used up to maximum temperatures between 400 and 600°C, depending upon grade. Compare this with neodymium-iron-boron's (NdFeB) maximum use temperatures of 150 to 220°C. Other advantages of SmCo over NdFeB include better corrosion resistance and greater magnetic output at temperatures above about 150°C.
Sensor applications requiring a stable magnetic field benefit from SmCo's low reversible temperature coefficient of induction: -0.030%/°C for Sm2Co17. The best NdFeB varies twice as much. The only common material with a lower coefficient than this is alnico, but with significantly lower magnetic output and resistance to de-magnetization.
MANUFACTURING
Precision Magnetic's samarium cobalt factory, is one of the world's more modern rare earth magnet manufacturing facilities and is equipped with state-of-the-art equipment throughout. A full range of material grades is available and the Company's continuous improvement philosophy ensures that improved materials will continue to be developed and introduced.
Arnold is one of only a few companies that custom manufactures both fully dense AND polymer bonded samarium cobalt. For information on polymer bonded Sm2Co17, please visit the Bonded Magnet section.
RoHS COMPLIANCE
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