Samarium-cobalt magnets are the second most powerfull magnets after the NdFeB and also are rare-earth metal based magnets like neodymium. The main components are samarium (Sm) and cobalt (Co), these two elements can be mixed in ratio 1:5 or 2:17. The final composition takes effect on magnetic and thermal parameters of magnets.
Production process is pressing in magnetic field and sintering, so SmCo is a hard and britle material with high energy product and very good resistant to external demagnetizing fields. SmCo magnets can be smaller than ferrite or AlNiCo magnets. SmCo magnets are produced only as anisotropic.
The main disadvantage of SmCo magnets is high content of cobalt, what results into high price, so they are used in applications where very small, high energy magnet is required and the ambient temperature is high.
Maximum working temperature of SmCo magnets is up to +250°C (SmCo5) and up to +300°C (Sm2Co17). SmCo magnets are not resistant to anorganic acids and solvents.
Table of magnetic properties of SmCo magnets:
|Coercivity Hc (kA/m)||
Max. energy product
Max. working temp.
|Normal Hcb||Intrinsic Hci|
|YX-20 (SmCo5)||0.90 - 0.94||680 - 725||1194 - 1830||127 - 143||<= 250|
|YX-24 (SmCo5)||0.96 - 1.00||730 - 770||1194 - 1830||175 - 190||<= 250|
|YXG-30 (Sm2Co17)||1.08 - 1.10||788 - 835||>= 1433||220 - 240||<= 300|
Other magnetic and mechanic parameters of SmCo magnets (SmCo5 / Sm2Co17):
|Temp. coefficient of Br (%/°C)||Temp. coefficient of Hci (%/°C)||Magnetizing field (kA/m)||Curie temp. (°C)||Density (g/cm3)||Hardness (Hv)|
|- 0.05 / - 0.03||- 0.3 / - 0.2||2000 / 4000||700 - 850||8.2 - 8.5||550 / 640|