Product Information
Sm2Co17 magnets(Sm2Co17) are mainly in proportion to the metals samarium, cobalt, copper, iron and zirconium. It has a (BH) maximum range of 20 to 32 and a maximum operating temperature of 350°C. Sm2Co17 has a very low temperature coefficient and good corrosion resistance. When working in a high temperature environment, the magnetic properties of samarium cobalt magnets are better than that of neodymium iron boron magnets. Therefore, samarium cobalt magnets are widely used in aerospace, defense, and sensors.
Due to the brittleness of the Sm2Co17 material, Sm2Co17 magnet is not suitable for discs or rings with complex shapes and thin thicknesses. Also due to this feature, some cosmetic defects may occur during production, inspection and magnetization. However, the magnetism will not be affected. They are generally similar in strength to neodymium magnets, but have higher temperature ratings and higher coercivity.
Attributes
-Extremely resistant to demagnetization
- Good temperature stability (maximum use temperatures between 250 °C (523 K) and 550 °C (823 K); Curie temperatures from 700 °C (973 K) to 800 °C (1,070 K)
- Expensive and subject to price fluctuations (cobalt is market price sensitive)
Physical and mechanical properties
Comparison of physical properties of sintered neodymium and Sm-Co magnets | ||
Property | Neodymium | Sm-Co |
Remanence (T) | 1–1.3 | 0.82–1.16 |
Coercivity (MA/m) | 0.875–1.99 | 0.493–1.59 |
Relative permeability | 1.05 | 1.05 |
Temperature coefficient of remanence (%/K) | −0.12 | −0.03 |
Temperature coefficient of coercivity (%/K) | −0.55..–0.65 | −0.15..–0.30 |
Curie temperature (°C) | 320 | 800 |
Density (g/cm3) | 7.3–7.5 | 8.2–8.4 |
CTE, magnetizing direction (1/K) | 5.2×10−6 | 5.2×10−6 |
CTE, normal to magnetizing direction (1/K) | −0.8×10−6 | 11×10−6 |
Flexural strength (N/mm2) | 250 | 150 |
Compressive strength (N/mm2) | 1100 | 800 |
Tensile strength (N/mm2) | 75 | 35 |
Vickers hardness (HV) | 550–650 | 500–650 |
Electrical resistivity (Ω·cm) | (110–170)×10−6 | 86×10−6 |
Production
The reduction/melt method and reduction/diffusion method are used to manufacture samarium–cobalt magnets. The reduction/melt method will be described since it is used for both SmCo5 and Sm2Co17 production. The raw materials are melted in an induction furnace filled with argon gas. The mixture is cast into a mold and cooled with water to form an ingot. The ingot is pulverized and the particles are further milled to further reduce the particle size. The resulting powder is pressed in a die of desired shape, in a magnetic field to orient the magnetic field of the particles. Sintering is applied at a temperature of 1100˚C–1250˚C, followed by solution treatment at 1100˚C–1200˚C and tempering is finally performed on the magnet at about 700˚C–900˚C.[citation needed] It then is ground and further magnetized to increase its magnetic properties. The finished product is tested, inspected and packed