Great care is required when handling magnetized material. Besides the high
forces there is also the risk that the brittle magnets can burst. Consequently gloves and
goggles should be compulsory. Furthermore, when machining NdFeB magnets
caution must be taken due to the high reactivity and inflammability of the powder.
Even irritationsof the respiratory organs can occur.
Samarium Cobolt Magnets (SmCo) are used in this thesis which are also part of
the rare earth family. The compound of Samarium Cobalt was discovered in 1966 by
Dr. Karl J. Strnat [5]. They were once the most powerful permanent magnet, but
NdFeB magnets have surpassed them. Samarium cobalt is a powdered metal which is
compacted when it is near a magnetic field and then sintered. Sintered means that
when a compacted powder magnet is exposed to heat treat operation, the full density
and magnetic orientation can be attained. SmCo magnets have also a very strong
23
magnetic field. They tend to resist demagnetization extremely well. Unlike
Neodymium magnets, it is also very corrosion resistant. SmCo magnets can operate at
higher temperatures up to 300°C and 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%.Two common
compositions of SmCo magnets are SmCo5 and Sm2Co17. They can be sintered and
bonded. Generally, the cost of SmCo magnets is higher than NdFeB magnets. But
NdFeB magnets are stronger than SmCo magnets.
FIGURE 3-7 SmCo magnets (Samarium Cobalt)
Material Information
1. An alloy compose of SmCo5/Sm2Co17 produce by powder metallurgical
method
2. Extremely hard & brittle
3. High demagnetization resistance
4. Excellent anti-corrosion properties
5. More expensive than NdFeB magnets because of limited raw material supply
6. Outstanding thermal stability
Typical Physical Properties
Curie Temperature (°C) 700-800
Maximum Operating Temperature (°C) 350
Resistivity (μ ohm.cm) 50-90
Hardness (Hv) 450-600
Density (g/cm3) 8.0-8.5
Relative Recoil Permeability (μrec) 1.10
Saturation Field Strength, kOe (kA/m) 37.5 (3000)
Temperature Coefficient of Br (%/°C) -0.05 ~ -0.03
Temperature Coefficient of iHc (%/°C) -0.25 ~ -0.19
Great care is required when handling magnetized material. Besides the high
forces there is also the risk that the brittle magnets can burst. Consequently gloves and
goggles should be compulsory. Furthermore, when machining NdFeB magnets
caution must be taken due to the high reactivity and inflammability of the powder.
Even irritationsof the respiratory organs can occur.
Samarium Cobolt Magnets (SmCo) are used in this thesis which are also part of
the rare earth family. The compound of Samarium Cobalt was discovered in 1966 by
Dr. Karl J. Strnat [5]. They were once the most powerful permanent magnet, but
NdFeB magnets have surpassed them. Samarium cobalt is a powdered metal which is
compacted when it is near a magnetic field and then sintered. Sintered means that
when a compacted powder magnet is exposed to heat treat operation, the full density
and magnetic orientation can be attained. SmCo magnets have also a very strong
23
magnetic field. They tend to resist demagnetization extremely well. Unlike
Neodymium magnets, it is also very corrosion resistant. SmCo magnets can operate at
higher temperatures up to 300°C and 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%.Two common
compositions of SmCo magnets are SmCo5 and Sm2Co17. They can be sintered and
bonded. Generally, the cost of SmCo magnets is higher than NdFeB magnets. But
NdFeB magnets are stronger than SmCo magnets.
FIGURE 3-7 SmCo magnets (Samarium Cobalt)
Material Information
1. An alloy compose of SmCo5/Sm2Co17 produce by powder metallurgical
method
2. Extremely hard & brittle
3. High demagnetization resistance
4. Excellent anti-corrosion properties
5. More expensive than NdFeB magnets because of limited raw material supply
6. Outstanding thermal stability
Typical Physical Properties
Curie Temperature (°C) 700-800
Maximum Operating Temperature (°C) 350
Resistivity (μ ohm.cm) 50-90
Hardness (Hv) 450-600
Density (g/cm3) 8.0-8.5
Relative Recoil Permeability (μrec) 1.10
Saturation Field Strength, kOe (kA/m) 37.5 (3000)
Temperature Coefficient of Br (%/°C) -0.05 ~ -0.03
Temperature Coefficient of iHc (%/°C) -0.25 ~ -0.19
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