Samarium Cobalt Magnets - SDM Magnetics Co., Ltd.

1: 5 type and 2:17 type sintered Samarium Cobalt magnets are called as the first generation and second generation of rare earth permanent magnets. 2:17 type is developed based on 1:5 type. Neodymium magnets dominated the market of rare earth permanent magnets since its inception and then Samarium Cobalt magnets are marginalized seriously due to magnetic performance, complex processing technologies, and costs. But in fact, sintered Samarium Cobalt magnet is still playing an irreplaceable role in high-temperature and high temperature stability applications which is not possible for Neodymium magnets. The research of high-performance sintered Samarium Cobalt magnets has never stopped, thus complex multistage heating treatment and microstructure control promoted magnetic performance of Samarium Cobalt magnets to an extreme. United States Department of Defense demanded that enhance the maximum operating temperature of sintered Samarium Cobalt magnet to the 500 degrees Celsius from 300 degrees Celsius to meet the new applications in aerospace in 1997. In the meanwhile, some higher high-end applications like travelling wave tube and internal device also asked reversible temperature coefficient of sintered Samarium Cobalt magnets should have small enough absolute value. Therefore, TbCu7-type structure Sm₂Co₇-based magnets emerged and gained widely concern.

Manufacturing Process of Sintered Samarium Cobalt Magnets

Magnetic Properties of Sintered Samarium Cobalt Magnets

Material	Grade	Remanence Br		Coercivity Hcb		Intrinsic Coercivity Hcj		Max. Energy Product (BH)max		Curie Temp Tc	Max. Oper Tem. Tw	Temp. Coeff. of Br	Temp. Coeff. of Hcj
Material	Grade	T	kGs	kA/m	KOe	kA	kOe	kJ/m³	MGOe	℃	℃	%/℃	%/℃
SmCo₅	RECo₅-16S	0.79-0.84	7.9-8.4	620-660	7.8-8.3	≥1830	≥23.0	118-135	15-17	750	250	-0.035	-0.28
	RECo₅-18S	0.84-0.89	8.4-8.9	660-700	8.3-8.8	≥1830	≥23.0	135-151	17-19	750	250	-0.040	-0.28
	RECo₅-20S	0.89-0.93	8.9-9.3	684-732	8.6-9.2	≥1830	≥23.0	150-167	19-21	750	250	-0.045	-0.28
	RECo₅-22S	0.92-0.96	9.2-9.6	710-756	8.9-9.5	≥1830	≥23.0	167-183	21-23	750	250	-0.045	-0.28
	RECo₅-24S	0.96-1.00	9.6-10.0	740-788	9.3-9.9	≥1830	≥23.0	183-199	23-25	750	250	-0.045	-0.28
(SmGd)Co₅	LTC-10	0.62-0.66	6.2-6.6	485-517	6.1-6.5	≥1830	≥23.0	75-88	9.5-11.0	750	300	20-100℃: +0.0156 100-200℃: +0.0087 200-300℃: +0.0007	–
Sm₂(Co,Fe,Cu,Zr)₁₇	RE₂Co₁₇-24H	0.95-1.02	9.5-10.2	692-764	8.7-9.6	≥1990	≥25.0	175-191	22-24	800	350	-0.025	-0.20
	RE₂Co₁₇-26H	1.02-1.05	10.2-10.5	740-788	9.4-10.0	≥1990	≥25.0	191-207	24-26	800	350	-0.030	-0.20
	RE₂Co₁₇-28H	1.03-1.08	10.3-10.8	756-812	9.5-10.2	≥1990	≥25.0	207-220	26-28	800	350	-0.035	-0.20
	RE₂Co₁₇-30H	1.08-1.10	10.8-11.0	788-835	9.9-10.5	≥1990	≥25.0	220-240	28-30	800	350	-0.035	-0.20
	RE₂Co₁₇-32H	1.10-1.13	11.0-11.3	812-860	10.2-10.8	≥1990	≥25.0	230-255	29-32	800	350	-0.035	-0.20
	RE₂Co₁₇-22	0.93-0.97	9.3-9.7	676-740	8.5-9.3	≥1433	≥18.0	160-183	20-23	800	300	-0.020	-0.20
	RE₂Co₁₇-24	0.95-1.02	9.5-10.2	692-764	8.7-9.6	≥1433	≥18.0	175-191	22-24	800	300	-0.025	-0.20
	RE₂Co₁₇-26	1.02-1.05	10.2-10.5	748-796	9.4-10.0	≥1433	≥18.0	191-207	24-26	800	300	-0.030	-0.20
	RE₂Co₁₇-28	1.03-1.08	10.3-10.8	756-812	9.5-10.2	≥1433	≥18.0	207-220	26-28	800	300	-0.035	-0.20
	RE₂Co₁₇-30	1.08-1.10	10.8-11.0	788-835	9.9-10.5	≥1433	≥18.0	220-240	28-30	800	300	-0.035	-0.20
	RE₂Co₁₇-32	1.10-1.13	11.0-11.3	812-860	10.2-10.8	≥1433	≥18.0	230-255	29-32	800	300	-0.035	-0.20
	RE₂Co₁₇-26M	1.02-1.05	10.2-10.5	676-780	8.5-9.8	955-1433	12-18	191-207	24-26	800	300	-0.035	-0.20
	RE₂Co₁₇-28M	1.03-1.08	10.3-10.8	676-796	8.5-10.0	955-1433	12-18	207-220	26-28	800	300	-0.035	-0.20
	RE₂Co₁₇-30M	1.08-1.10	10.8-11.0	676-835	8.5-10.5	955-1433	12-18	220-240	28-30	800	300	-0.035	-0.20
	RE₂Co₁₇-32M	1.10-1.13	11.0-11.3	676-852	8.5-10.7	955-1433	12-18	230-255	29-32	800	300	-0.035	-0.20
	RE₂Co₁₇-24L	0.95-1.02	9.5-10.2	541-716	6.8-9.0	636-955	8-12	175-191	22-24	800	250	-0.025	-0.20
	RE₂Co₁₇-26L	1.02-1.05	10.2-10.5	541-748	6.8-9.4	636-955	8-12	191-207	24-26	800	250	-0.035	-0.20
	RE₂Co₁₇-28L	1.03-1.08	10.3-10.8	541-764	6.8-9.6	636-955	8-12	207-220	26-28	800	250	-0.035	-0.20
	RE₂Co₁₇-30L	1.08-1.15	10.8-11.5	541-796	6.8-10.0	636-955	8-12	220-240	28-30	800	250	-0.035	-0.20
	RE₂Co₁₇-32L	1.10-1.15	11.0-11.5	541-812	6.9-10.2	636-955	8-12	230-255	29-32	800	250	-0.035	-0.20
(Sm,Er)₂(Co,Tm)₁₇	LTC-16	0.81-0.85	8.1-8.5	605-669	7.6-8.4	≥1592	≥20	117-127	14-16	840	300	-50-20℃: +0.005 20-100℃: -0.008 100-200℃: -0.008 200-300℃: -0.011	–
	LTC-18	0.85-0.90	8.5-9.0	629-708	7.9-8.9	≥1592	≥20	127-143	16-18	840	300
	LTC-20	0.90-0.94	9.0-9.4	661-732	8.3-9.2	≥1592	≥20	143-159	18-20	840	300
	LTC-22	0.94-0.97	9.4-9.7	685-740	8.6-9.3	≥1592	≥20	159-175	20-22	840	300
The above-mentioned data of magnetic properties and physical properties are given at room temperature. The max working temperature of magnet is changeable due to length-diameter ratio, coating thickness and other environment factors.

Physical Properties of Sintered Samarium Cobalt Magnets

Parameters	Unit	SmCo₅	Sm₂Co₁₇
Density / ρ	g/cm³	8.1-8.5	8.3-8.5
Vickers Hardness	HV	450-500	500-600
Compressive Strength	MPa	420-680	700-830
Electrical Resistivity	Ω·cm	(5-6)x10^-5	(8-9)x10^-5
Coeff. of Thermal Expansion	10^-6/K	C⊥: 13 C∥: 6	C⊥: 11 C∥: 8

Performance Difference between Different Magnetic Material

Material	(BH)max MGOe	Hcj kOe	Temper. Coeff. of Br %/℃	Max. Operating Temper ℃	Anti-corrosition Capability
SmCo₅	16-25	15-25	-0.05	200-250	Good
Sm₂Co₁₇	22-32	6-30	-0.03	250-350	Good
Nd₂Fe₁₄B	26-52	12-33	-0.11	80-230	Bad
Ferrite	3.0-4.5	3.0-4.5	-0.19	200-300	Good
AlNiCo	5-10	1.0-1.8	-0.03	450-500	Excellent

Notes:

Actually, sintered Samarium Cobalt magnets are not suitable to be structure part due to inherent brittleness.
SmCo5 magnets are relatively easier to machine compared to Sm2Co17 magnets.
Customers who purchase non-magnetize Samarium Cobalt magnets should equip appropriate magnetizing equipment to ensure saturated magnetization.
SDM also serve coated Samarium Cobalt magnets to use under harsh environments.