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PERMANENT MAGNETIC MATERIALS

At A Glance...

LITERATURE DOWNLOADS

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.

GradeMaximum
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
MGOekGkOekOe°C°C% / °C% / °C
Type 2:17
S30103011.2109.2300825-0.03-0.17
S26102610.5108.8300825-0.03-0.17
S32123211.51210.0300825-0.03-0.17
S30123011.3129.8300825-0.03-0.17
S26122610.6129.4300825-0.03-0.17
S2212229.9129.0300825-0.03-0.17
S33153311.71510.7300825-0.03-0.22
S32153211.51510.5300825-0.03-0.22
S30153011.31510.3300825-0.03-0.22
S28162811.0

16

10.3300825-0.03-0.22
S26162610.81610.1300825-0.03-0.22
S321832

11.6

1810.8300825-0.03-0.22
S30183011.31810.6300825-0.03-0.22
S26182610.71810.1300825-0.03-0.22
S28202811.02010.4300825-0.03-0.22
S26202610.82010.3300825-0.03-0.22
S3022 3011.31910.5300825-0.03-0.22
S28252811.12510.5300825-0.03-0.22
S26252610.82510.2300825-0.03-0.22
S24252410.3259.8350825-0.03-0.22
S2225229.7259.2350825-0.03-0.22
S28302811.03010.5300825-0.03-0.22
S26302610.83010.3300825-0.03-0.22
S24302410.3309.8350825-0.03-0.22
S2230229.7309.3350825-0.03-0.22
S24352410.3359.9350825-0.03-0.22
S2235229.7359.3350825-0.03-0.22
Type 1:5
S24152410.0159.3250750-0.05-0.22
S2215229.5158.8250750-0.05-0.22
S24182410.0189.4250750-0.05-0.22
S2218229.5189.0250750-0.05-0.22
S2018209.0188.5250750-0.05-0.22
S1818188.6188.2250750-0.05-0.22
S2220229.5209.1250750-0.05-0.22
S2020209.0208.6250750-0.05-0.22
S1820188.6208.2250750-0.05-0.22
S2223229.5239.1250750-0.05-0.22
S2025209.0258.6250750-0.05-0.22
S1825188.6258.2250750-0.05-0.22
S2030209.0308.6250750-0.05-0.22

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.