Samarium cobalt magnets are important rare earth magnets used in various applications. They are available in various series and grades. The popular series are series1-5 (SmCo5) and samarium cobalt magnets Series 2-17 (Sm2Co17)
Series 1-5 have one atom of rare earth Samarium and five atoms of Cobalt. These samarium cobalt magnets have a reversible temperature coefficient of -0.05°C. Through moderate magnetizing field saturation, magnetization can be achieved . By nucleation, coercivity is controlled. From 1-5 series, various cobalt magnet alloys like S1665, S1865, S2064 etc. are manufactured.
Samarium cobalt magnets Series 2-17 (Sm2Co17) are composed of rare earth Samarium Cobalt and 13-17 atoms of transition metals (TM). Transition metal though rich in cobalt also contains elements like zirconium,hafnium and such may be added in small quantities to achieve better heat treatment response. Of all rare earth elements these alloys have the best reversible temperature coefficient.
The bonded samarium cobalt materials are typically anisotropic. These magnets are manufactured by using binders such as epoxy resins to hold the powder in place. For holding, sometimes sintering is also done.
Samarium cobalt magnets after processing do not need any coatings or platings. However if cleanliness is an issue, the magnets can be coated by using advance coatings. The coating acts like a sealant. The occasional discoloring of magnet is due to the presence of iron impurities. The rusting appearance is typically localized in areas and after some discoloration, does not continue through the material.
If the magnet is intended to be used in vacuum, it is plated with nickel. The brittleness of the samarium cobalt necessitates the use of diamond grinding wheel. Proper precaution must be taken as the samarium cobalt powder can spontaneously ignite from just a small electrostatic spark.
Cobalt magnet can be magnetized by using very large magnetizing fields to saturate the material. In the event, the samarium cobalt magnet is inside an assembly, greater fields are required to ensure saturation.