What Are Samarium Cobalt Magnets?
Samarium cobalt magnets are part of the rare earth magnet family, specifically made from an alloy of samarium and cobalt. They were developed in the 1970s and have since been valued for their high magnetic strength and stability over a wide temperature range. Unlike your fridge magnets, these are used in sophisticated technologies such as in medical devices, aerospace, and even in space exploration!
Grades of Samarium Cobalt Magnets and Their Magnetic Properties
| Grade |
Remanence (BR) mT (KGS) |
Coercive Force (Hcb) kA/m (kOe) |
Intrinisc Coercive Force (Hcj) kA/m (kOe) |
Max. Energy Product (BH) max kJ/m3 (MGOe) |
Max. Operating Temp TW |
|---|---|---|---|---|---|
| SmCo16 |
810-850 (8.1-8.5) |
660 (8.3) |
1830 23 |
110-127 (14-16) |
250°C |
| SmCo18 |
850-900 (8.5-9.0) |
700 (8.8) |
1830 (23) |
127-143 (16-18) |
250°C |
| SmCo20 |
900-940 (9.0-9.4) |
725 (9.1) |
1830 (23) |
150-167 (19-21) |
250°C |
| SmCo22 |
920-960 (9.2-9.6) |
750 (9.4) |
1830 (23) |
160-175 (20-22) |
250°C |
| SmCo24 |
960-1000 (9.6-10.0) |
770 (9.7) |
1830 (23) |
175-190 (22-24) |
250°C |
| SmCo18S |
850-900 (8.5-9.0) |
700 (8.8) |
2000 (25) |
135-151 (17-19) |
250°C |
| SmCo20S |
900-940 (9.0-9.4) |
725 (9.1) |
2000 (25) |
143-160 (18-20) |
250°C |
| SmCo22S |
920-960 (9.2-9.6) |
750 (9.4) |
2000 (25) |
160-175 (20-22) |
250°C |
| Grade |
Remanence (BR) mT (KGS) |
Coercive Force (Hcb) kA/m (kOe) |
Intrinisc Coercive Force (Hcj) kA/m (kOe) |
Max. Energy Product (BH) max kJ/m3 (MGOe) |
Max. Operating Temp TW |
|---|---|---|---|---|---|
| SmCo24L |
950-1020 (9.5-10.2) |
716 (9.0) |
955 (12) |
175-191 (22-24) |
350°C |
| SmCo26L |
1020-1050 (10.2-10.5) |
748 (9.4) |
955 (12) |
191-207 (24-26) |
350°C |
| SmCo28L |
1030-1080 (10.3-10.8) |
765 (9.9) |
955 (12) |
207-220 (26-28) |
350°C |
| SmCo30L |
1080-1150 (10.8-11.5) |
795 (10.0) |
955 (12) |
220-240 (28-30) |
350°C |
| SmCo32L |
1100-1150 (11.0-11.5) |
810 (10.2) |
955 (12) |
230-255 (22-24) |
350°C |
| SmCo26M |
1020-1050 (10.2-10.5) |
780 (9.8) |
1273 (16) |
191-207 (24-26) |
350°C |
| SmCo28M |
1030-1080 (10.3-10.8) |
796 (10.0) |
1273 (16) |
207-220 (26-28) |
350°C |
| SmCo30M |
1080-1100 (10.8-11.0) |
835 (10.5) |
1273 (16) |
220-240 (28-30) |
350°C |
| SmCo32M |
1100-1130 (11.0-11.3) |
845 (10.6) |
1273 (16) |
230-255 (29-32) |
350°C |
| SmCo26 |
1020-1050 (10.2-10.5) |
780 (9.8) |
1434 (19) |
191-207 (24-26) |
350°C |
| SmCo28 |
1030-1080 (10.3-10.8) |
796 (10.0) |
1435 (20) |
207-220 (26-28) |
350°C |
| SmCo30 |
1080-1100 (10.8-11.0) |
835 (10.5) |
1436 (21) |
220-240 (28-30) |
350°C |
| SmCo32 |
1100-1130 (11.0-11.3) |
845 (10.6) |
1194 (15) |
230-255 (29-32) |
350°C |
| SmCo24H |
950-1020 (9.5-10.2) |
750 (9.4) |
1990 (25) |
175-191 (22-24) |
350°C |
| SmCo26H |
1020-1050 (10.2-10.5) |
780 (9.8) |
1990 (25) |
191-207 (24-26) |
350°C |
| SmCo28H |
1030-1080 (10.3-10.8) |
796 (10.0) |
1990 (25) |
207-220 (26-28) |
350°C |
| SmCo30H |
1080-1100 (10.8-11.0) |
835 (10.5) |
1990 (25) |
220-240 (28-30) |
350°C |
So what are the factors that affect the magnetic properties of samarium cobalt magnets? Below are 10 factors that affect the magnetic properties of samarium cobalt magnets.
- Temperature Stability
- Curie Temperature
- Coercivity
- Remanence
- Microstructure
- Manufacturing Process
- Aging Effects
- Environmental Factors
- Material Purity
- Magnet Size and Shape
Temperature Stability
One of the standout features of samarium cobalt magnets is their excellent temperature stability. These magnets can operate effectively over a wide temperature range, from -40°C to 350°C. This makes them ideal for applications where they are exposed to extreme temperatures, such as in engines and turbines. The ability to maintain magnetic properties at high temperatures is a key factor in their widespread use.
Curie Temperature
The Curie temperature is the temperature above which a magnet loses its permanent magnetic properties. Samarium cobalt magnets have a high Curie temperature, typically between 700°C and 850°C. This high Curie temperature contributes to their thermal stability, ensuring they remain effective even in high-temperature environments.
Coercivity
Coercivity refers to the resistance of a magnet to becoming demagnetized. Samarium cobalt magnets have high coercivity, meaning they can withstand external magnetic fields without losing their magnetism. This makes them highly reliable for use in environments with strong magnetic interference.
Remanence
Remanence is the measure of the magnetization left in a magnet after an external magnetic field is removed. Samarium cobalt magnets exhibit high remanence, indicating strong residual magnetism. This characteristic is crucial for applications requiring consistent magnetic performance over time.
Microstructure
The microstructure of samarium cobalt magnets plays a significant role in determining their magnetic properties. The arrangement and size of the grains within the magnet can impact its strength and stability. Fine-grained structures tend to enhance the magnet's overall performance, providing better magnetic properties and durability.
Manufacturing Process
The manufacturing process of samarium cobalt magnets can also influence their properties. Factors such as the sintering temperature, cooling rate, and machining techniques can all affect the final product. Precision in manufacturing ensures that the magnets meet the desired specifications and performance criteria.
Aging Effects
Over time, all magnets experience some degree of aging, which can affect their magnetic properties. Samarium cobalt magnets are known for their excellent aging resistance, maintaining their performance over extended periods. However, environmental factors such as humidity and exposure to certain chemicals can still cause gradual degradation.
Environmental Factors
Environmental factors, including humidity, temperature fluctuations, and exposure to corrosive substances, can impact the performance of samarium cobalt magnets. Although these magnets are generally resistant to corrosion, prolonged exposure to harsh environments can still cause degradation.
Material Purity
The purity of the raw materials used in the production of samarium cobalt magnets is crucial. Impurities can weaken the magnet's structure and reduce its overall performance. Ensuring high-purity samarium and cobalt in the alloy helps maintain the desired magnetic properties.
Magnet Size and Shape
The size and shape of samarium cobalt magnets can also influence their magnetic properties. Smaller magnets can have higher coercivity but lower overall strength, while larger magnets provide more substantial magnetic fields. The shape of the magnet can affect how the magnetic field is distributed, impacting its performance in specific applications.
Conclusion
In conclusion, samarium cobalt magnets are fascinating and powerful tools used in many advanced technologies. Their magnetic properties are influenced by a variety of factors, from their composition and manufacturing process to environmental conditions and aging. Understanding these factors helps in selecting the right magnet for each application, ensuring optimal performance and reliability.
FAQs
1. What are samarium cobalt magnets used for?
Samarium cobalt magnets are used in high-performance applications such as medical devices, aerospace technologies, and industrial equipment due to their strong and stable magnetic properties.
2. How does temperature affect samarium cobalt magnets?
Temperature stability is one of the strengths of samarium cobalt magnets. They can operate effectively in a wide range of temperatures, from -40°C to 350°C, and have a high Curie temperature, ensuring they remain effective even in high-temperature environments.
3. What is coercivity in samarium cobalt magnets?
Coercivity refers to a magnet's resistance to becoming demagnetized. Samarium cobalt magnets have high coercivity, making them reliable in environments with strong magnetic interference.
4. Why is the purity of materials important in samarium cobalt magnets?
High-purity materials are crucial in producing samarium cobalt magnets because impurities can weaken the magnet's structure and reduce its overall performance. Ensuring the use of high-purity samarium and cobalt helps maintain the desired magnetic properties.
5. How do aging effects impact samarium cobalt magnets?
Samarium cobalt magnets are known for their excellent aging resistance, maintaining their performance over extended periods. However, environmental factors such as humidity and exposure to certain chemicals can still cause gradual degradation.
