SmCo magnets known as Samarium, Samarium Cobalt or rare earth Cobalt magnets, are the second generation of rare earth permanent magnets. They have been commercialized since the early 1970's, which opened the door towards the development and commercialization of NdFeB magnets. According to the difference between the production technologies, SmCo can be divided into bonded SmCo and sintered SmCo, but we are only specialized in sintered SmCo.
The sintered SmCo are anisotropic and can only be magnetized in the orientation direction. In general, magnetizing fields of about 35 to 55 kOe are required to saturate SmCo. They consist mainly of Sm (Samarium) and Co (Coblat), and they are available with two series of materials, SmCo5 and Sm2Co17 often referred to as SmCo 1:5 and SmCo 2:17. SmCo5 have lower energy, Hcj (intrinsic coercive force), maximum operation temperature and Curie temperature than Sm2Co17, but SmCo5 are easier to magnetize to saturation.
They are available in a number of grades that span a wide range of properties and application requirements. They are powerful, with (BH)max range of 14MGOe~32MGOe; however, they are also very brittle and prone to cracking and chipping, so they must be handled with care and adequate protective gear. Due to their relative frailty, mechanisms and applications in which the magnet are used must be adapt and designed to support the material.
Characteristics
.High magnetic values – Br high to 11.3 kG (1.13 T) and (BH)max high to 32 MGOe (255 kJ/m3)
.High working temperature – maximum working temperature high to 250ºC~350ºC
.Outstanding thermal stability – α(Br) low to -0.03 %/ºC and β(Hcj) low to -0.2%/ºC
.Execellent corrosion resistance – no surface treatment needed
.Execellent demagnetization resistance –maximum Hcj higher than 25 kOe (1990 kA/m)
Applications
Due to their characteristics above, SmCo are the ideal magnetic material in following applications, particularly where the magnets are required to operate at high temperatures, across a broad temperature range, with stable magnetic field, or in a corrosive environment:
.Travelling Wave Tubes
.Circulators
.Isolators
.Speakers
.Magnetron Sputtering Cathodes
.Sensors
.Wind Turbines
.Servo Motors
.Pump Couplings
.Chemical Pumps
.Magnetic Assemblies or Magnetic Systems
Physical Properties
Characteristics |
Reversible Temperature Coefficient 20-150ºC, α(Br) |
Reversible Temperature Coefficient 20-150ºC, β(Hcj) |
Coefficient of Thermal Expansion |
Thermal Conductivity |
Specific Heat |
Curie Temperature |
Flexural Strength |
Density |
Hardness, Vickers |
Electrical Resistivity |
Unit |
%/ºC |
%/ºC |
ΔL/L per ºCx10-6 |
kcal/mhrºC |
cal/gºC |
ºC |
Mpa |
g/cm3 |
Hv |
μΩ • cm |
SmCo5 |
-0.04 |
-0.2 |
//6⊥12 |
9.5 |
0.072 |
750 |
150-180 |
8.3 |
450-550 |
50~60 |
Sm2Co17 |
-0.03 |
-0.2 |
//9⊥11 |
8.5 |
0.068 |
850 |
130-150 |
8.4 |
550-650 |
80~90 |
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