Samarium Cobalt (Sm-Co)
The first commercially viable rare earth permanent magnet material, samarium-cobalt (Sm-Co), is considered to still be the premium material for many high performance applications. Formulated in the 1960s, it came as a revolutionary product, initially tripling the energy product of other materials available at the time.
Sm-Co materials come in energy products from 16 MGOe up to 33 MGOe. Their high resistance to demagnetizing influences and excellent thermal stability has ensured Sm-Co as the premium choice for the most demanding motor applications. In addition, the corrosion resistance is significantly higher than, for example, Nd-Fe-B. However, we would still recommend coating the magnet in acidic conditions. Its corrosion resistance has also offered a high degree of comfort to those looking to use magnets in medical applications.
On a 'per pound' basis, Sm-Co is the most expensive permanent magnet material. However, because of its high energy product, it has achieved considerable commercial success by decreasing the required volume of magnet material to fulfill a certain task. Sm-Co can typically be used up to 300 °C, though, of course, its actual performance at that temperature is governed strongly by the design of the magnetic circuit. The (approximately) linear demagnetization curve of Sm-Co materials allows repeatable performance over a wide range of operating conditions. As with all permanent magnet materials, extreme caution must be exe rcised when handling magnetized samples. Sm-Co can be prone to chipping and should not be used a structural component in an assembly.
| Grade |
Maximum
Energy
Product
BHmax |
Residual
Induction
Br |
Minimum
Intrinsic
Coercivity
Hci |
Coercivity
Hc |
Maximum
Operating
Temp
Tmo |
Curie Temp
Tc |
Coefficient
Induction
20-150 °C]
α |
Coefficient
Coercivity
20-150 °C]
β |
| MGOe |
kG |
kOe |
kOe |
°C |
°C |
% / °C |
% / °C |
| Type 2:17 |
|
|
|
|
|
|
|
|
| S3010 |
30 |
11.2 |
10 |
9.2 |
300 |
825 |
-0.03 |
-0.17 |
| S2610 |
26 |
10.5 |
10 |
8.8 |
300 |
825 |
-0.03 |
-0.17 |
| S3212 |
32 |
11.5 |
12 |
10.0 |
300 |
825 |
-0.03 |
-0.17 |
| S3012 |
30 |
11.3 |
12 |
9.8 |
300 |
825 |
-0.03 |
-0.17 |
| S2612 |
26 |
10.6 |
12 |
9.4 |
300 |
825 |
-0.03 |
-0.17 |
| S2212 |
22 |
9.9 |
12 |
9.0 |
300 |
825 |
-0.03 |
-0.17 |
| S3315 |
33 |
11.7 |
15 |
10.7 |
300 |
825 |
-0.03 |
-0.22 |
| S3215 |
32 |
11.5 |
15 |
10.5 |
300 |
825 |
-0.03 |
-0.22 |
| S3015 |
30 |
11.3 |
15 |
10.3 |
300 |
825 |
-0.03 |
-0.22 |
| S2816 |
28 |
11.0 |
16
|
10.3 |
300 |
825 |
-0.03 |
-0.22 |
| S2616 |
26 |
10.8 |
16 |
10.1 |
300 |
825 |
-0.03 |
-0.22 |
| S3218 |
32 |
11.6
|
18 |
10.8 |
300 |
825 |
-0.03 |
-0.22 |
| S3018 |
30 |
11.3 |
18 |
10.6 |
300 |
825 |
-0.03 |
-0.22 |
| S2618 |
26 |
10.7 |
18 |
10.1 |
300 |
825 |
-0.03 |
-0.22 |
| S2820 |
28 |
11.0 |
20 |
10.4 |
300 |
825 |
-0.03 |
-0.22 |
| S2620 |
26 |
10.8 |
20 |
10.3 |
300 |
825 |
-0.03 |
-0.22 |
| S2825 |
28 |
11.1 |
25 |
10.5 |
300 |
825 |
-0.03 |
-0.22 |
| S2625 |
26 |
10.8 |
25 |
10.2 |
300 |
825 |
-0.03 |
-0.22 |
| S2425 |
24 |
10.3 |
25 |
9.8 |
350 |
825 |
-0.03 |
-0.22 |
| S2225 |
22 |
9.7 |
25 |
9.2 |
350 |
825 |
-0.03 |
-0.22 |
| S2830 |
28 |
11.0 |
30 |
10.5 |
300 |
825 |
-0.03 |
-0.22 |
| S2630 |
26 |
10.8 |
30 |
10.3 |
300 |
825 |
-0.03 |
-0.22 |
| S2430 |
24 |
10.3 |
30 |
9.8 |
350 |
825 |
-0.03 |
-0.22 |
| S2230 |
22 |
9.7 |
30 |
9.3 |
350 |
825 |
-0.03 |
-0.22 |
| S2435 |
24 |
10.3 |
35 |
9.9 |
350 |
825 |
-0.03 |
-0.22 |
| S2235 |
22 |
9.7 |
35 |
9.3 |
350 |
825 |
-0.03 |
-0.22 |
| Type 1:5 |
|
|
|
|
|
|
|
|
| S2415 |
24 |
10.0 |
15 |
9.3 |
250 |
750 |
-0.05 |
-0.22 |
| S2215 |
22 |
9.5 |
15 |
8.8 |
250 |
750 |
-0.05 |
-0.22 |
| S2418 |
24 |
10.0 |
18 |
9.4 |
250 |
750 |
-0.05 |
-0.22 |
| S2218 |
22 |
9.5 |
18 |
9.0 |
250 |
750 |
-0.05 |
-0.22 |
| S2018 |
20 |
9.0 |
18 |
8.5 |
250 |
750 |
-0.05 |
-0.22 |
| S1818 |
18 |
8.6 |
18 |
8.2 |
250 |
750 |
-0.05 |
-0.22 |
| S2220 |
22 |
9.5 |
20 |
9.1 |
250 |
750 |
-0.05 |
-0.22 |
| S2020 |
20 |
9.0 |
20 |
8.6 |
250 |
750 |
-0.05 |
-0.22 |
| S1820 |
18 |
8.6 |
20 |
8.2 |
250 |
750 |
-0.05 |
-0.22 |
| S2223 |
22 |
9.5 |
23 |
9.1 |
250 |
750 |
-0.05 |
-0.22 |
| S2025 |
20 |
9.0 |
25 |
8.6 |
250 |
750 |
-0.05 |
-0.22 |
| S1825 |
18 |
8.6 |
25 |
8.2 |
250 |
750 |
-0.05 |
-0.22 |
| S2030 |
20 |
9.0 |
30 |
8.6 |
250 |
750 |
-0.05 |
-0.22 |
|
Typical Physical Properities - Type 2:17
|
|
|
Curie Temperature
|
800 - 825 °C
|
|
*Coefficient of Thermal Expansion - Perpendicular to magnetization orientation
|
+11.0 - +12.0 x 10-6 °C-1
|
|
*Coefficient of Thermal Expansion - Parallel to magnetization orientation
|
+9.0 - +10.0 x 10-6 °C-1
|
|
Electrical Resistivity
|
80 - 90 µΩ·cm
|
|
Density
|
8.3 - 8.4 g·cm-3
|
|
Vicker's Hardness
|
550 - 650 Hv
|
|
Young's Modulus
|
140 - 150 kN·mm-2
|
|
Bending Strength
|
0.09 - 0.15 kN·mm-2
|
|
Compressive Strength
|
0.65 - 0.80 kN·mm-2
|
|
Typical Physical Properities -Type 1:5
|
|
|
Curie Temperature
|
720 - 750 °C
|
|
*Coefficient of Thermal Expansion - Perpendicular to magnetization orientation
|
+12.0 - +13.0 x 10-6 °C-1
|
|
*Coefficient of Thermal Expansion - Parallel to magnetization orientation
|
+6.0 - +7.0 x 10-6 °C-1
|
|
Electrical Resistivity
|
50 - 60 µΩ·cm
|
|
Density
|
8.2 - 8.3 g·cm-3
|
|
Vicker's Hardness
|
550 - 550Hv
|
|
Young's Modulus
|
100 - 110 kN·mm-2
|
|
Bending Strength
|
0.12 - 0.18 kN·mm-2
|
|
Compressive Strength
|
0.9 - 1.0 kN·mm-2
|
*Due to magnetostriction, all magnetic materials expand/contract at different rates, depending on magnetic orientation.
|