Home >> Magnetic Materials >> Sintered SmCo Magnets

rare earth permanent magnets, sintered samarium cobalt, smco magnetsSintered SmCo magnets, i.e. sintered samarium cobalt magnets, are those permanent magnetic materials that based on a hexagonal crystal structure (1:5 type SmCo magnets) or a rhombohedral crystal structure (2:17 type SmCo magnets), and they are manufactured through a powder metallurgy process. They contain two basic elements samarium and cobalt. The samarium element can be substituted by a portion of other rare earth elements including praseodymium (Pr), cerium (Ce), gadolinium (Gd), erbium (Er), etc. The cobalt element can be substituted by a portion of iron (Fe) element to increase the magnets’ saturation magnetization (Ms). In order to control the microstructure and the microchemistry so as to meet required performance, it is also critical to add a small portion of copper (Cu), zirconium (Zr), titanium (Ti), etc.

According to crystal structure, samarium cobalt magnets include SmCo5 magnets (1st generation of REPMs) and Sm2Co17 magnets (2nd generation of REPMs). They were invented/developed by K. Strnat’s team in the 1960s and T. Ojima’s team in the 1970s, respectively. Due to their high Curie temperature (Tc: 700-850 ºC), middle high maximum energy product ((BH)max: 110-260 kJ/m3), low temperature coefficients of remanence (α(Br): +0.01 to -0.05 %/°C) and coercivity (β(Hcj): -0.2 to -0.3 %/°C) and high corrosion resistance, sintered SmCo magnets are mainly applied in high temperature motors, servo motors, stepper/stepping motors, traveling wave tubes (TWTs), circulators, isolators, klystrons, undulators, gyroscopes, accelerometers, instruments and meters, etc.

>> Sintered SmCo Magnets’ Grades and Their Magnetic Properties

   
GradeBr Hcb Hcj (BH)max Tw
kGs T kOe kA/m kOe kA/m MGOe kJ/m3 ºC
XGS32H 11.0-11.5 1.10-1.15 ≥10.2 ≥812 ≥25 ≥1990 30-32 239-255 ≤350
XGS30H 10.7-11.2 1.07-1.12 ≥9.9 ≥788 28-30 223-239
XGS28H 10.4-10.9 1.04-1.09 ≥9.6 ≥764 26-28 207-223
XGS26H 10.0-10.5 1.00-1.05 ≥9.2 ≥732 24-26 191-207
XGS24H 9.7-10.2 0.97-1.02 ≥8.9 ≥708 22-24 175-191
XGS22H 9.3-9.8 0.93-0.98 ≥8.5 ≥676 20-22 159-175
XGS20H 9.0-9.5 0.90-0.95 ≥8.2 ≥653 18-20 143-159
XGS32 11.0-11.5 1.10-1.15 ≥10.0 ≥796 ≥18 ≥1433 30-32 239-255 ≤300
XGS30 10.7-11.2 1.07-1.12 ≥9.7 ≥772 28-30 223-239
XGS28 10.4-10.9 1.04-1.09 ≥9.4 ≥748 26-28 207-223
XGS26 10.0-10.5 1.00-1.05 ≥9.0 ≥716 24-26 191-207
XGS24 9.7-10.2 0.97-1.02 ≥8.7 ≥692 22-24 175-191
XGS22 9.3-9.8 0.93-0.98 ≥8.3 ≥660 20-22 159-175
XGS20 9.0-9.5 0.90-0.95 ≥8.0 ≥637 18-20 143-159
XGS32M 11.0-11.5 1.10-1.15 ≥9.0 ≥716 ≥12 ≥955 30-32 239-255 ≤300
XGS30M 10.7-11.2 1.07-1.12 ≥8.7 ≥692 28-30 223-239
XGS28M 10.4-10.9 1.04-1.09 ≥8.5 ≥676 26-28 207-223
XGS26M 10.0-10.5 1.00-1.05 ≥8.5 ≥676 24-26 191-207
XGS24M 9.7-10.2 0.97-1.02 ≥8.5 ≥676 22-24 175-191
XGS22M 9.3-9.8 0.93-0.98 ≥8.2 ≥653 20-22 159-175
XGS20M 9.0-9.5 0.90-0.95 ≥8.0 ≥637 18-20 143-159
XGS32L 11.0-11.5 1.10-1.15 ≥6.8 ≥541 ≥8 ≥636 30-32 239-255 ≤250
XGS30L 10.7-11.2 1.07-1.12 ≥6.8 ≥541 28-30 223-239
XGS28L 10.4-10.9 1.04-1.09 ≥6.6 ≥525 26-28 207-223
XGS26L 10.0-10.5 1.00-1.05 ≥6.6 ≥525 24-26 191-207
XGS24L 9.7-10.2 0.97-1.02 ≥6.5 ≥517 22-24 175-191
XGS22L 9.3-9.8 0.93-0.98 ≥6.5 ≥517 20-22 159-175
XGS20L 9.0-9.5 0.90-0.95 ≥6.5 ≥517 18-20 143-159
XGS24LT 9.7-10.2 0.97-1.02 ≥8.7 ≥692 ≥18 ≥1433 22-24 175-191 ≤300
XGS22LT 9.3-9.8 0.93-0.98 ≥8.3 ≥660 20-22 159-175
XGS20LT 9.0-9.5 0.90-0.95 ≥8.0 ≥637 18-20 143-159
XGS18LT 8.5-9.0 0.85-0.90 ≥7.5 ≥597 16-18 127-143
XGS16LT 8.0-8.5 0.80-0.85 ≥7.0 ≥557 14-16 111-127
XGS14LT 7.5-8.0 0.75-0.80 ≥6.5 ≥517 12-14 95-111
XG24H 9.7-10.2 0.97-1.02 ≥9.2 ≥730 ≥23 ≥1830 22-24 175-191 ≤250
XG22H 9.3-9.8 0.93-0.98 ≥8.8 ≥700 20-22 159-175
XG20H 9.0-9.5 0.90-0.95 ≥8.5 ≥676 18-20 143-159
XG18H 8.5-9.0 0.85-0.90 ≥8.2 ≥653 16-18 127-143
XG16H 8.0-8.5 0.80-0.85 ≥7.8 ≥620 14-16 111-127
XG24 9.7-10.2 0.97-1.02 ≥9.2 ≥730 ≥15 ≥1194 22-24 175-191 ≤250
XG22 9.3-9.8 0.93-0.98 ≥8.8 ≥700 20-22 159-175
XG20 9.0-9.5 0.90-0.95 ≥8.5 ≥676 18-20 143-159
XG18 8.5-9.0 0.85-0.90 ≥8.2 ≥653 16-18 127-143
XG16 8.0-8.5 0.80-0.85 ≥7.8 ≥620 14-16 111-127
Note:
∗ The data in the above table were samples’ results tested at the temperature of 20 °C.
∗ The prefixes XGS and XG are for Sm2Co17 and SmCo5 magnets, respectively.
∗ The typical temperature coefficients of Br and Hcj are α(Br): -0.03~-0.05 %/ºC and β(Hcj): -0.20~-0.30 %/ºC, respectively.
∗ The suffix LT means low/near-zero temperature coefficient of Br (α(Br): +0.01 ~ -0.03 %/°C).
∗ The above data are only for reference, magnets can be tailored according to customers’ personalized requirements.

>> Sintered SmCo Magnets’ shapes, Magnetization Direction and Size Range

Shape Graphic Description Magnetization Direction Size Range
Disc/Cylinder disc neodymium magnets size range Disc/Cylinder neodymium magnets Axially Magnetized Axially Magnetized D: 1-100 mm
T: 0.5-100 mm
Disc/Cylinder neodymium magnets Diametrically Magnetized Diametrically Magnetized D: 1-100 mm
T: 0.5-100 mm
Ring ring neodymium magnets size range ring neodymium magnets Axially Magnetized Axially Magnetized OD: 1.5-100 mm
ID: 0.5-90 mm
T: 0.5-60 mm
ring neodymium magnets Diametrically Magnetized Diametrically Magnetized OD: 1.5-100 mm
ID: 0.5-90 mm
T: 0.5-60 mm
Block/Rectangular block neodymium magnets size range block neodymium magnets Thickness Magnetized Thickness Magnetized L: 1-160 mm
W: 0.5-100 mm
T: 0.5-100 mm
Arc/Segment arc/segment neodymium magnets size range arc/segment_neodymium_magnets_Diametrically_magnetization Diametrically Magnetized OD-ID≥1mm
L: 1-120 mm
W: 3-100 mm
H: 1-60 mm
arc/segment neodymium magnets Radially Magnetized Radially Magnetized OD-ID≥1mm
L: 1-50 mm
W: 3-30 mm
H: 1-10 mm
Note:
∗ Other shapes of sintered SmCo magnets can also be tailored according to customers’ specific requirements.

>> Sintered SmCo Magnets’ Coating Types

Because of strong corrosion resistance, sintered SmCo magnets usually do not need any coating. If any coating is required, nickel, zinc, tin, epoxy, Teflon and other types are available.

>> Some Physical Properties of Sintered SmCo Magnets

Parameter Unit Value
Density (ρ) g/cm3 8.2-8.4
Curie Temperature (Tc) ºC 700-850
Recoil Permeability (μrec) - 1.05-1.10
Vickers Hardness (HV) MPa 400-600
Bending Strength (σbb) MPa 150-180
Compressive Strenght (σbc) MPa 800-1000
Tensile Strength (σb) MPa 35-40
Resistivity (ρ) μΩ·m 0.5-0.9
Thermal Expansivity ∥ Magnetization (α) 10-6/ºC 5-9
Thermal Expansivity ⊥ Magnetization (α) 10-6/ºC 10-13
Note:
∗ The above data are only for reference, specific magnets maybe have different values.