Magnete und Handel

Magnets Samarium Cobalt

The temperature-resistant material for high-quality permanent magnets.

Samarium-cobalt magnets

Tridelta’s samarium-cobalt magnets are characterized by a very high energy product with good temperature stability. It is a permanent magnet material based on intermetallic ferromagnetic compounds of rare earths – preferably samarium (Sm) with cobalt (Co).

Features / Advantages

  • High magnetic strength
  • Suitable for higher temperatures
  • High magnetic stability
  • Corrosion resistant

Application areas

Samarium-cobalt magnets have a wide range of applications, therefore only a few examples of use can be mentioned here:

Electric, servo, DC, synchronous and linear motors
Central rotary and spur rotary couplings
Hysteresis and eddy current brakes
Adhesive applications

Magnet production

The SmCo powder for the magnets made of samarium cobalt is obtained from finished alloys by grinding and then pressed in powder presses under the application of a magnetic field to form so-called green compacts. Depending on the material grade, these green compacts are sintered at different temperatures in a vacuum or under inert gas. This achieves between 96% and 99% of the theoretical density. The raw magnets are then heat-treated for optimum development of the magnetic properties.

Magnet shapes

Samarium-cobalt magnets from Tridelta can be produced in all shapes that can be manufactured by pressing. They are supplied as cuboids, cylinders, rings, segments and other molded parts. Holes, recesses, grooves, etc. can also be made provided they are parallel to the pressing direction. On request, Tridelta will check whether a pressing tool is available for the desired geometry.

In addition to compression molding, indirect shaping (cutting) of magnets is also possible for the production of high quality and precise small magnets. Tridelta offers you all kinds of customized solutions in cuboid or profile. The small parts of about 30mg unit weight upwards are cut out of larger block magnets using diamond tools.

Temperature behavior

As with all magnetic materials, the magnetic properties of samarium-cobalt magnets depend on temperature. Within the operating temperature range, the original values are largely restored after one temperature cycle and the changes are reversible. Depending on the design and application, minor permanent changes may also occur initially. They can be anticipated by artificial aging. Although the maximum possible operating temperature for SmCo magnets is between 250°C and 350°C, depending on the material, it also depends on the position of the operating point.

Under certain conditions, the magnet material can be adapted, which also allows operating temperatures of up to 450 °C.

Chemical and mechanical properties

Due to their chemical composition, SmCo magnets from Tridelta are resistant to organic acids and are not susceptible to corrosion. However, SmCo materials tend to oxidize at higher temperatures due to the pronounced affinity of samarium for oxygen and its generally high bonding propensity. In addition, they are not resistant to inorganic acids and alkalis. In practice, however, this is not a problem, because a specially developed corrosion protection technology can effectively and permanently protect the surfaces of samarium-cobalt magnets.

As a result of the high brittleness of samarium-cobalt magnets, impact stress must be avoided when screwing or reinforcing. When completing with different materials, the different expansion coefficients must be taken into account. Magnetized magnets, for example, attract iron filings and dust. Therefore it is recommended, where possible, to magnetize the magnets only after mounting.

Magnetic properties

The samarium-cobalt magnet is anisotropic and can therefore only be magnetized in the preferred magnetic direction. The achievable magnetic properties with Tridelta SmCo magnets also depend significantly on their design and size. The samarium-cobalt magnet is very stable against field-related losses. The magnetic stability under thermal changes is almost as good for SmCo magnets as for AlNico magnets.

1) Designation based on DIN 17410/IEC 60404-8-1
2) The maximum possible operating temperature depends on the dimensioning of the system.
3) Depending on the operating temperature: 20 to 200 °c: -0.008 %/K; 200 – 300 °C: -0.011 %/K