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SmCo Magnet

Samarium–cobalt (SmCo) magnet, a type of rare earth magnet, is a strong permanent magnet made of an alloy of samarium and cobalt. They were developed in the early 1960s based on work done by Dr. Karl Strnat and Dr. Alden Rey at Wright-Patterson AFB and the University of Dayton, respectively. In particular, Dr. Strnat and Dr. Rey developed the first formulation of Sm-Co5. They are generally ranked similarly in strength to neodymium magnets, but have higher temperature ratings and higher coercivity. They are brittle, and prone to cracking and chipping. Samarium–cobalt magnets have maximum energy products (BHmax) that range from 16 megagauss-oersteds (MGOe) to 33 MGOe, that is approx. 128 kJ/m3 to 264 kJ/m3; their theoretical limit is 34 MGOe, about 272 kJ/m3.

Sintered Samarium Cobalt magnets exhibit magnetic anisotropy, meaning they can only be magnetized in the axis of their magnetic orientation. This is done by aligning the crystal structure of the material during the manufacturing process.

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

Samarium - cobalt magnet has a strong resistance to corrosion and oxidation resistance, usually do not need to be coated can be widely used in high temperature and poor working conditions.

Specifications of SmCo Magnet

Type

(BH)max

Remanence

Br

Instrinsic Coercivity

Normal Coercivity

TC

 

KJ/m3

MGOe

mT

KG

KA/m

KOe

KA/m

KOe

1:5

YX-18

127-143

16-18

850-900

8.5-9.0

1194-1513

15-19

620-650

7.8-8.2

250

1:5

YX-20

150-167

19-21

920-960

9.2-9.6

1194-1513

15-19

653-717

8.2-9.0

250

1:5

YX-24

175-190

22-24

960-1000

9.6-10

1194-1513

15-19

730-770

9.2-9.7

250

1:5

YXG-24

175-190

22-24

950-1020

9.5-10.2

1433-1990

18-25

637-732

8.0-9.2

300

1:5

YXG-26

191-207

24-26

1020-1050

10.2-10.5

1433-1990

18-25

748-796

9.4-10.0

300

1:5

YXG-28

205-220

26-28

1050-1080

10.5-10.8

1433-1990

18-25

756-796

9.5-10.0

300

1:5

YXG-28B

205-220

26-28

1020-1100

10.2-11.0

440-520

5.5-6.5

414-517

5.2-6.5

300

1:5

YXG-30

220-240

28-30

1080-1100

10.8-11.0

1433-1990

18-25

780-835

9.8-10.5

300

1:5

YXG30B

220-240

28-30

1080-1100

10.8-11.0

440-520

5.5-6.5

414-446

5.2-5.6

300