Samarium Cobalt (SmCo) disc magnets retain magnetic stability in high-temperature and chemically corrosive environments where Neodymium (NdFeB) magnets degrade or oxidize. Composed of rare-earth Samarium and Cobalt, these discs operate continuously up to 300°C (Sm2Co17) with a low thermal coefficient of remanence (-0.030% / °C). Production utilizes powder metallurgy, magnetic-field alignment, liquid-phase sintering, and diamond grinding.
Technical Specifications
|
Parameter |
Sm2Co17 (High-Energy) |
Sm1Co5 (High-Temperature) |
|
Residual Induction (Br) |
10.5 - 11.8 kGs |
8.2 - 9.2 kGs |
|
Coercivity (Hcb) |
>= 9.0 kOe |
>= 6.5 kOe |
|
Intrinsic Coercivity (Hcj) |
>= 15 kOe |
>= 15 kOe |
|
Max. Energy Product ((BH)max) |
24 - 33 MGOe |
16 - 22 MGOe |
|
Max. Operating Temperature |
250°C - 300°C |
250°C |
|
Reversible Temp. Coef. of Br |
-0.030% / °C |
-0.045% / °C |
|
Density |
8.4 g/cm3 |
8.3 g/cm3 |
|
Vickers Hardness (HV) |
450 - 550 |
400 - 500 |
Key Features
Thermal Stability: Operates up to 300°C with minimal irreversible flux loss.
Oxidation Resistance: Contains no free iron in Sm2Co17 phases, eliminating plating requirements in non-acidic atmospheres.
Brittle Structure: High hardness and low tensile strength require mechanical retention (bonding or clamping) rather than interference press-fits.
Applications
High-temperature brushless DC motors and sensor actuators in engine nacelles.
Traveling-wave tubes, microwave devices, and radar assemblies.
MWD (Measurement While Drilling) sensors and magnetic couplings rated above 200°C.
MRI gradient coils and NMR spectrometers.
Customization
Alloy Selection: Choose between Sm1Co5 for baseline thermal stability or Sm2Co17 for maximum energy product up to 300°C.
Surface Treatment: Apply optional Nickel-Copper-Nickel, Parylene, or epoxy coatings for chemical and moisture resistance.
Precision Machining: Specify tight dimensional tolerances down to +/-0.01 mm via multi-axis diamond grinding.
Magnetic Calibration: Request customized flux sorting within +/-1% nominal Gauss output for synchronized rotor assemblies.
Manufacturing & Quality Control
Production Steps
• Melting: Vacuum induction melting (VIM) of Samarium and Cobalt.
• Milling: Nitrogen closed-loop jet milling (D50 approx. 3-4 um).
• Compaction: Isostatic pressing in a >= 2.0 T orienting magnetic field.
• Sintering: Vacuum sintering followed by homogenization and aging heat treatments.
• Machining: Wire-EDM and multi-axis diamond wheel grinding.
Inspection Equipment
• Permeameter: Hysteresis graph testing up to 300°C.
• CMM: Mitutoyo 3D coordinate measuring for dimensional verification.
• Helmholtz Coils: Total magnetic moment and flux mapping.
• Optical Microscopes: Micro-crack and edge-chipping screening.
Packaging & Documentation
Export Packaging: Cold-rolled steel sheet magnetic shielding complying with IATA Packing Instruction 953, nested in anti-static foam and double-walled corrugated boxes.
Documentation: Material Test Report (MTR), lot-specific hysteresis loop curves, Certificate of Conformance (CoC), and MSDS.
FAQ
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