Samarium Cobalt: High-performance magnets for extreme conditions

Samarium Cobalt (SmCo) is a class of high-performance permanent magnets consisting of an alloy of samarium (Sm) and cobalt (Co). These magnets belong to the family of rare earth magnets and are characterised by their high temperature resistance, corrosion resistance and magnetic strength. They are the first generation of commercial rare earth magnets and were introduced in the 1970s.

Properties of samarium-cobalt magnets

• High magnetic energy: Samarium-cobalt magnets have a maximum energy product (BH)ₘₐₓ of up to 30 MGOe, which is lower than that of neodymium magnets, but still very powerful.
• Temperature resistance: These magnets retain their magnetic properties at temperatures of up to 300°C and are therefore ideal for high-temperature applications.
• Corrosion resistance: In contrast to neodymium magnets, samarium cobalt magnets are less susceptible to corrosion and generally do not require an additional protective coating.
• High coercivity: The magnets are insensitive to external magnetic interference and retain their magnetisation even in difficult environments.

Manufacture of samarium-cobalt magnets

Samarium-cobalt magnets are manufactured using a sintering process:

1. Alloy: Samarium and cobalt are fused to form an alloy.
2. Powdering: The alloy is ground into a fine powder to ensure a homogeneous mixture.
3. Shaping: The powder is pressed in a mould under high pressure, often in a strong magnetic field, to align the magnetic moments.
4. Sintering: The pressed material is heated at high temperatures to increase density and strength.
5. Magnetising: Finally, the material is magnetised in a strong magnetic field.

Applications of samarium-cobalt magnets

Due to their special properties, samarium-cobalt magnets are used in demanding environments:

• Space travel: The temperature and corrosion resistance makes them ideal for use in satellites and spacecraft.
• Military: SmCo magnets are used in precision weapons, radar systems and other military technologies.
• Medical technology: They are used in implants, medical sensors and devices such as magnetic resonance imaging (MRI) scanners.
• High-temperature motors: They ensure reliable performance in turbines and motors that are exposed to extreme temperatures.
• Industry: SmCo magnets are used in sensors, generators and magnetic couplings, especially in corrosive environments.

Differences to neodymium magnets

Although samarium-cobalt magnets cannot quite keep up with neodymium magnets in terms of magnetic strength, they offer some decisive advantages:

• Higher temperature resistance (up to 300°C, while neodymium magnets reach their limits at around 150°C).
• Better corrosion resistance as they do not require a protective coating.
• Longer durability in extreme environments.

Interesting facts about samarium-cobalt magnets

Did you know that samarium-cobalt magnets play a key role in space travel? Their ability to withstand extreme temperatures and radiation conditions makes them indispensable for satellites and space probes. They are also considered pioneers of modern rare earth magnets and paved the way for the development of more powerful neodymium magnets.