Samarium Cobalt Magnets

Samarium cobalt (SmCo) magnets are strong permanent magnets made of samarium, cobalt, and other minor elements. It is known for its high magnetic strength and good temperature stability. Samarium cobalt magnets are generally weaker than neodymium magnets at room temperature, but they perform reliably in extreme temperatures when neodymium magnets stop working. Since SmCo is highly resistant to corrosion and oxidation, coatings are generally not required. Since the samarium cobalt magnet is made by sintering, it is very brittle and cracks may appear inside.

Sm1Co5

SmCo5 alloy contains one samarium atom for every five cobalt atoms, and is the first generation of samarium cobalt magnets. The (BH)max of 1:5 SmCo alloys is from 15 MGOe to 25 MGOe and the service temperature is up to 250°C. SmCo5 mainly contains Sm and Co and does not contain iron, so it has better resistance to corrosion and demagnetization.

Sm2Co17

Compared with Sm1Co5, the magnetic properties of 2:17 SmCo alloy are better. Its (BH)max usually varies between 24 MGOe and 32 MGOe, and its working temperature can reach 300 °C. Sm2Co17 contains very few other elements such as iron, copper, and samarium and cobalt. The withdrawal of iron from this alloy means that it may corrode slightly in high humidity environments, so Sm2Co17 magnets are coated with nickel in some cases.

 

Application of Samarium Cobalt Magnets

SmCo magnets have excellent magnetic properties, good thermal and chemical stability, and are widely used in high-speed motors and generators, military applications, microwave communication technology, etc. But cobalt is an expensive and scarce strategic metal element, and samarium is a rare metal element. The earth element, causes the high price of this magnet. The high price makes it only available in limited areas and limits its development.

PERFORMANCE TABLE OF SMCO MAGNETS

GRADE

REMANENCE

Br

COERCIVE FORCE

Hcb

INTRINSIC COERCIVE FORCE

Hcj

 (BH)max HIGHEST WORKING TEMPERATURE DENSITY
T kGs kA/m kOe kA/m kOe kJ/m3 MGOe ˚C g/cm3
Sm1Co5-16 0.79-0.84 7.9-8.4 620-660 7.8-8.3 ≥1830 ≥23 118-135 15-17 ≤250 8.3
Sm1Co5-18 0.84-0.89 8.4-8.9 660-700 8.3-8.8 ≥1830 ≥23 135-151 17-19 ≤250 8.3
Sm1Co5-20 0.89-0.93 8.9-9.3 684-732 8.6-9.2 ≥1830 ≥23 150-167 19-21 ≤250 8.3
Sm1Co5-22 0.92-0.96 9.2-9.6 710-756 8.9-9.5 ≥1830 ≥23 167-183 21-23 ≤250 8.3
Sm1Co5-24 0.96-1.00 9.6-10.0 740-788 9.3-9.9 ≥1830 ≥23 183-199 23-25 ≤250 8.3
Sm2Co17-24L 0.95-1.02 9.5-10.2 541-716 6.8-9.0 636-955 8-12 175-191 22-24 ≤250 8.4
Sm2Co17-26L 1.02-1.05 10.2-10.5 541-784 6.8-9.4 636-955 8-12 191-207 24-26 ≤250 8.4
Sm2Co17-28L 1.03-1.08 10.3-10.8 541-764 6.8-9.6 636-955 8-12 207-220 26-28 ≤250 8.4
Sm2Co17-30L 1.08-1.15 10.8-11.5 541-796 6.8-10.0 636-955 8-12 220-240 28-30 ≤250 8.4
Sm2Co17-32L 1.10-1.15 11.0-11.5 541-812 6.8-10.2 636-955 8-12 230-255 29-32 ≤250 8.4
Sm2Co17-26M 1.02-1.05 10.2-10.5 676-780 8.5-9.8 955-1433 12-18 191-207 24-26 ≤300 8.4
Sm2Co17-28M 1.03-1.08 10.3-10.8 676-796 8.5-10.0 955-1433 12-18 207-220 26-28 ≤300 8.4
Sm2Co17-30M 1.08-1.1 10.8-11.0 676-835 8.5-10.5 955-1433 12-18 220-240 28-30 ≤300 8.4
Sm2Co17-32M 1.10-1.13 11.0-11.3 676-852 8.5-10.7 955-1433 12-18 230-255 29-32 ≤300 8.4
Sm2Co17-33M 1.13-1.15 11.3-11.5 820-870 10.3-10.9 955-1433 12-18 246-262 31-32 ≤300 8.4
Sm2Co17-22 0.93-0.97 9.3-9.7 676-740 8.5-9.3 ≥1433 ≥18 160-183 20-23 ≤300 8.4
Sm2Co17-24 0.95-1.02 9.5-10.2 692-764 8.7-9.6 ≥1433 ≥18 175-191 22-24 ≤300 8.4
Sm2Co17-26 1.02-1.05 10.2-10.5 748-796 9.4-10.0 ≥1433 ≥18 191-207 24-26 ≤300 8.4
Sm2Co17-28 1.03-1.08 10.3-10.8 756-812 9.5-10.2 ≥1433 ≥18 207-220 26-28 ≤300 8.4
Sm2Co17-30 1.08-1.10 10.8-11.0 788-835 9.9-10.5 ≥1433 ≥18 220-240 28-30 ≤300 8.4
Sm2Co17-32 1.10-1.13 11.0-11.3 812-860 10.2-10.8 ≥1433 ≥18 230-255 29-32 ≤300 8.4
Sm2Co17-33 1.13-1.15 11.3-11.5 820-870 10.3-10.9 ≥1433 ≥18 246-262 31-32 ≤300 8.4
Sm2Co17-24H 0.95-1.02 9.5-10.2 692-764 8.7-9.6 ≥1990 ≥25 175-191 22-24 ≤350 8.4
Sm2Co17-26H 1.02-1.05 10.2-10.5 748-796 9.4-10.0 ≥1990 ≥25 191-207 24-26 ≤350 8.4
Sm2Co17-28H 1.03-1.08 10.3-10.8 756-812 9.5-10.2 ≥1990 ≥25 207-220 26-28 ≤350 8.4
Sm2Co17-30H 1.08-1.10 10.8-11.0 788-835 9.9-10.5 ≥1990 ≥25 220-240 28-30 ≤350 8.4
Sm2Co17-32H 1.10-1.13 11.0-11.3 812-860 10.2-10.8 ≥1990 ≥25 230-255 29-32 ≤350 8.4
Sm2Co17-33H 1.13-1.15 11.3-11.5 830-880 10.4-11 ≥1990 ≥25 246-262 31-32 ≤350 8.4
Sm2Co17-20TR 0.9-0.94 9.0-9.4 661-732 8.3-9.2 ≥1592 ≥20 143-159 18-20 ≤500 8.4
Sm2Co17-16LT 0.81-0.85 8.1-8.5 605-669 7.6-8.4 ≥1592 ≥20 111-127 14-16 ≤300 8.4
Sm2Co17-18LT 0.85-0.9 8.5-9.0 629-708 7.9-8.9 ≥1592 ≥20 127-143 16-18 ≤300 8.4
Sm2Co17-20LT 0.9-0.94 9.0-9.4 661-732 8.3-9.2 ≥1592 ≥20 143-159 18-20 ≤300 8.4
Sm2Co17-22LT 0.94-0.97 9.4-9.7 685-740 8.6-9.3 ≥1592 ≥20 159-175 20-22 ≤300 8.4