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Samarium Cobalt Magnets (SmCo)

Sintered Samarium-Cobalt magnets (also known as SmCo) date back to the early 1970s and were the first example of rare earth magnets.

They are composed of a Samarium and Cobalt alloy. They are generally less powerful than Neodymium magnets but have two considerable advantages:

  • excellent thermal behaviour
  • high resistance to corrosion

These two characteristics allow the magnetic properties to diminish less as the temperature rises compared to Neodymium, together with the possibility of using them without the need for coatings or surface treatments.

They are suitable for applications requiring high thermal stability and corrosion resistance.

They reach their maximum performance when used on:

  • Brushless motors in the harshest conditions
  • Constant output generators, regardless of the operating temperature
SAMARIUM – COBALT
SmCo5 SmCo17
Curie temperature °C 710 770
Recoil permeability (µr) 1.03 1.05
Saturation field kOe > 25 > 50
Electrical resistivity _ Ω cm 50 80
Compressive strength N/mm2 ~ 850 ~ 800
Density g/cm3 8.3 8.5
Flexural strength N/mm2 100 – 150 100 – 150
Tensile strength N/mm2 50 40
Hardness – Vickers HV ~ 600 ~ 600
Young’s Modulus 103N/mm2 150 150
Specific heat kcal/kg.°C 0.08 – 0.09 0.08 – 0.09
Thermal conductivity kcal/m/hr/°C 8 8 – 9
Coeff. of thermal expansion // 10-6/°C 7 10
Coeff. of thermal expansion_ 10-6/°C 12 12