Temperature-compensated Samarium-cobalt Magnet

Overview

Coatings

While SmCo magnets inherently resist corrosion, optional coatings are available for specific functional or environmental needs:

Nickel (Ni): Enhances solderability for electronic assemblies (e.g., PCB-mounted sensors) 

Parylene: Used in medical devices (e.g., MRI gradient coils) to prevent biocompatibility issues 

Gold/Zinc: Low-resistivity coatings for high-frequency applications (e.g., microwave tubes) 

Epoxy: Mechanical protection in industrial settings (e.g., oil drilling equipment) 

Applications

Temperature-compensated SmCo magnets are critical in industries requiring thermal stability and precision:

Aerospace/Defense: Satellite gyroscopes (drift <10⁻⁵°/hr), missile guidance systems 

Medical: MRI gradient coils (0.1 T/m precision), surgical robotics 

Energy: Downhole drilling sensors (175°C+ environments), wind turbine generators 

Electronics: Traveling wave tubes (10–40 GHz), high-temperature micro-motors 

FAQs

How does temperature compensation work?

Doping with Gd/Tb/Dy reduces αBr (e.g., Gd10.3wt% achieves αBr ≈ -0.01%/°C), while fine cellular structures stabilize Hcj 

Are coatings necessary?

Rarely, except for soldering or biocompatibility requirements 

Comparison to NdFeB?

SmCo outperforms in thermal stability (NdFeB degrades above 150°C) but has lower room-temperature Br

Can they be machined?

Yes, but only with diamond tools or EDM due to brittleness (flexural strength <2 MPa√m) 

Cost drivers?

High rare-earth content (e.g., Tb/Dy) and complex heat treatments increase costs (~$40–80/kg for Sm)