Samarium cobalt magnets (SmCo) are composed of samarium, cobalt and iron. They have been available since the early 1970s. This sort of rare earth magnet is very powerfull, however they are also very brittle and prone to cracking and chipping.
The material poses a fire hazard if ground when dry, since the grinding dust has a low temperature ignition point.
Attributes
- High resistance to demagnetization
- High energy (magnetic strength is strong for its size)
- Good temperature stability (maximum use temperatures between 250 and 350°C; Curie temperatures from 700 to 800°C)
- Expensive material (cobalt is market price sensitive)
Material properties
- Density (g/cc): 8.4
- Electrical Resistivity (Ohm/cm) 0.8×10-4
- Coefficient of Thermal Expansion (perpendicular to axis) (10-6/k) 12.5