Samarium Cobalt Magnets
As 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. It is still recommended to coat 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. As with all permanent magnet materials, extreme caution must be exercised when handling magnetized samples. Sm-Co can be prone to chipping and should not be used a structural component in an assembly.
Grade(click to view demagnetization curve)
Max Energy Product
Residual Induction
Min Intrinsic Coercivity
Coercivity
Max Operating Temp
Curie Temp
Coefficient Induction 20-150°C
Coefficient Coercivity 20-150°C
BHmax
Br
Hci
Hc
Tmax
Tc
α
β
MGOe
kG
kOe
kOe
°C
°C
% / °C
% / °C
Type 2:17
30
11.2
10
9.2
300
825
-0.03
-0.017
26
10.5
10
8.8
300
825
-0.03
-0.17
32
11.5
12
10.0
300
825
-0.03
-0.17
30
11.3
12
9.8
300
825
-0.03
-0.17
26
10.6
12
9.4
300
825
-0.03
-0.17
22
9.9
12
9.0
300
825
-0.03
-0.17
32
11.5
15
10.5
300
825
-0.03
-0.22
30
11.3
15
10.3
300
825
-0.03
-0.22
28
11.0
16
10.3
300
825
-0.03
-0.22
26
10.8
16
10.1
300
825
-0.03
-0.22
32
11.6
18
10.8
300
825
-0.03
-0.22
30
11.3
18
18
300
825
825
-0.22
26
10.7
18
10.1
300
825
-0.03
-0.22
28
11.0
20
10.4
300
825
-0.03
-0.22
26
10.8
20
10.3
300
825
-0.03
-0.22
30
11.3
19
10.5
300
825
-0.03
-0.22
28
11.1
25
10.5
300
825
0.03
0.22
26
10.8
25
10.2
300
825
-0.03
-0.22
24
10.3
25
9.8
350
825
-0.03
-0.22
22
9.7
25
9.2
350
825
-0.03
-0.22
28
11.0
30
10.5
350
825
-0.03
-0.22
26
10.8
30
10.3
350
825
-0.03
-0.22
24
10.3
30
9.8
350
825
-0.03
-0.22
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
22
9.7
35
9.3
350
825
-0.03
-0.22
Type 1:5
24
10.0
15
9.3
250
750
-0.05
-0.22
22
9.5
15
8,8
250
750
-0.05
-0.22
24
10.0
18
9.4
250
750
-0.05
-0.22
22
9.5
18
9.0
250
750
-0.05
-0.22
20
9.0
18
8.5
250
750
-0.05
-0.22
18
8.6
18
8.2
250
750
-0.05
-0.22
22
9.5
9.5
9.1
250
750
-0.05
-0.22
20
9.0
20
8.6
250
250
-0.05
-0.22
18
8.6
20
8.2
250
750
-0.05
-0.22
22
9.5
23
9.1
250
750
-0.05
-0.22
20
9.0
25
8.6
250
750
-0.05
-0.22
18
8.6
25
8.2
250
750
-0.05
-0.22
20
9.0
30
8.6
250
750
-0.05
-0.22
Typical Physical Properties - 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
Vicker's Hardness
550 - 650 HV
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.
Typical Physical Properties - 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
Vicker's Hardness
550 - 650 HV
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.