Samarium Cobalt Magnets
What are Samarium Cobalt Magnets?
Samarium cobalt magnets are rare earth magnets that offer the best quality and value when comparing performance and size in high temperature environments (more on this below). They are extremely strong and typically allow for smaller size magnet profiles. Though not as strong as neodymium magnets, samarium cobalt magnets present three significant advantages:
- They work over a wider temperature range.
- They have superior temperature coefficients
- They have a greater resistance to corrosion.
Since samarium cobalt offers excellent corrosion resistance, these magnets typically do not require a surface treatment. They also have good resistance to external demagnetizing fields because of their High Intrinsic Coercive Force (Hci). This resistance makes samarium cobalt rare earth magnets an excellent choice for electromechanical applications.
They are available in three grades; 18, 22 and 26. The samarium cobalt magnet energy products of these alloys are 18 Mega Gauss Oersteds (MGOe), 22 (MGOe) and 26 (MGOe). The magnets are rich in cobalt and contain other elements such as iron and copper.
One of the Most Useful Magnets for High Temperatures
Samarium cobalt magnets resist corrosion and retain most of their energy up to 575° Fahrenheit, making them ideal replacements for Alnico magnets when high temperature use or miniaturization is required. They have good temperature stability—maximum use temperatures are between 250 and 550°C; Curie temperatures range from 700 to 800°C.
They will work in applications that require the system to function at cryogenic (or very hot) temperatures—over 350°F or 180°C. In applications where performance is required to be consistent with temperature change, the flux density of a samarium cobalt magnet will vary under 5% per 100°C change in temperature (in the range of 25–250°C or 77-480°F). Rare earth sintered samarium cobalt magnets are extremely resistant to demagnetization and they can operate at temperatures up to 500°F (260°C).
Applications of Samarium Cobalt
Common applications and typical uses for samarium cobalt magnets include technical applications where elevated temperatures apply, such as:
- Automotive “Under-the-Hood” Applications
Some more specific uses of samarium cobalt magnets are in motors, compact high force magnetic assemblies, turbomachinery, dipole assemblies, microphones, speakers, sputtering arrays for vacuum deposition, triggering hall sensors, particle accelerators and many other applications.
Things to Know When Using Samarium Cobalt Magnets
Samarium cobalt magnets are extremely hard and brittle and should be protected from shock and mechanical forces when handled in their application. Ones that are relatively thin compared to their pole cross-section (Magnetic Length / Pole Area) will demagnetize easier than those that are thick. Magnetic geometries utilizing backing plates, yokes, or return path structures will respond better to increased temperatures. A BuyMagnets.com team member can help determine if custom machining is required or if “pressed to size” option is possible.
- Samarium cobalt is manufactured by a sintering process, and inherent cracks are possible.
- Samarium cobalt magnets can easily chip; eye protection must be worn when handling them.
- Samarium cobalt alloys are typically machined in an unmagnetized state, using a wet grinding process. The grinding waste produced must not be allowed to completely dry as samarium cobalt has a low ignition point.
- Keep samarium cobalt magnets away from children.