Besides being especially qualified for extremely high temperatures – typically up to 250-350°C – samarium cobalt magnets have the following advantages:
- High magnetic strength (nearly same range as sintered NdFeB)
- High resistance to demagnetization
- Low thermal coefficient
- Very high working temperature
- High temperature stability
- Good corrosion resistance
SmCo magnets are produced by powder compaction followed by a sintering process. Mainly because of the cobalt contents of the magnets, these types of magnets are a more expensive solution.
Samarium cobalt magnets do not corrode easily but for medium to very corrosive environments, some kind of surface treatment or incapsulation is recommended.
Characterizing magnets
The most important properties to take into consideration for characterising the magnets are:
- Magnetic properties such as remanence Br, coercivity Hcb, intrinsic coercivity Hcj and max. energy product (B•H)max
- Dimensions and tolerances
- Force (for holding magnets), Torque (for motors), Field strength (for sensors)
- Minimum and maximum operating and working temperatures
- Area of application usage – e.g. humid/aqueous environment
- Requirements concerning surface coating
