Strontium Ferrite Magnet Powder
Bonded (SFP) · Wet-Press Sintered (SFP-W) · Dry-Press Sintered (SFP-D)
Full-line strontium and barium ferrite powder supplier: SFP fine powders for injection-molded, compression-bonded, and calendered flexible magnets; SFP-W wet-press anisotropic powders for high energy product sintered magnets; and SFP-D dry-press powders for isotropic and high-performance anisotropic parts. Consistent particle size distribution, high coercivity, and lot-to-lot uniformity trusted by magnet manufacturers worldwide.
Bonded Powder Grades & Specifications (SFP)
Our Sr-ferrite bonded powders are produced through a controlled ceramic process (pre-sintering → milling → annealing), yielding hexagonal M-type ferrite particles with precise magnetic properties. Available in isotropic and anisotropic grades.
| Grade | Br (mT) | Hcb (kA/m) | Hcj (kA/m) | (BH)max (kJ/m³) | D50 (μm) | Application |
|---|---|---|---|---|---|---|
| SFP-1.5 | 230-250 | 160-180 | 240-280 | 9.5-11.5 | 1.2-1.8 | Injection molding (PA6/PA12 binder) |
| SFP-2.0 | 240-260 | 170-195 | 260-310 | 10.5-12.5 | 1.5-2.2 | Compression bonded (epoxy binder) |
| SFP-3.0 | 250-270 | 185-210 | 280-340 | 12.0-14.5 | 0.8-1.5 | Calendered flexible sheet/strip |
| SFP-A | 225-245 | 155-175 | 220-265 | 9.0-10.5 | 1.0-1.6 | Anisotropic general purpose |
Sintered Powder — Wet-Press Anisotropic Grades (SFP-W)
Wet-press anisotropic strontium ferrite powders (SrFe₁₂O₁₉) for the manufacture of high energy product sintered magnets. These grades are used mainly in medium and high-end speaker rings, magnetic separation equipment, household appliances, and automotive motor arcs and rotors. Supplied either as pre-sintered coarse granulate ready for wet milling in your plant, or as fine powder for direct slurry preparation — matching your existing milling and dispersion workflow.
| Grade | Material | Br (mT) | Hcb (kA/m) | Hcj (kA/m) | (BH)max (kJ/m³) | Shrinkage (%) | Coarse Powder (μm) | Fine Powder (μm) |
|---|---|---|---|---|---|---|---|---|
| SFP-W4 | SrFe₁₂O₁₉ | 385-395 | 215-231 | 223-255 | 27.9-31.1 | 12.0-14.0 | 3-6 | 0.80-0.90 |
| SFP-W5 | SrFe₁₂O₁₉ | 400-410 | 223-239 | 223-255 | 30.3-33.5 | 12.0-14.5 | 3-6 | 0.68-0.80 |
| SFP-W6 | SrFe₁₂O₁₉ | 405-415 | 255-271 | 263-295 | 30.3-31.9 | 11.0-13.0 | 2-5 | 0.65-0.75 |
| SFP-W9.1 | SrFe₁₂O₁₉ | 440±10 | 262.5±12 | 286.5±12 | 36.0±1.6 | 11.0±1 | — | 0.6±0.02 |
| SFP-W9.2 | SrFe₁₂O₁₉ | 430±10 | 318.5±12 | 358.3±12 | 35.0±1.6 | 11.0±1 | — | 0.6±0.02 |
| SFP-W9.3 | SrFe₁₂O₁₉ | 420±10 | 318.5±12 | 397.9±12 | 33.5±1.6 | 11.0±1 | — | 0.6±0.02 |
Magnetic values measured on laboratory wet-pressed, sintered test specimens per IEC 60404-8-1. Shrinkage references apply to the magnetizing (orientation) direction. SFP-W9.x grades are ultra-fine, high-coercivity powders for premium motor applications.
Sintered Powder — Dry-Press Grades (SFP-D)
Two dry-press families cover the full application spectrum: SFP-D1 isotropic barium ferrite powders for micro motors, advertising magnets, stationery, and sealing strips; and SFP-D2.x high-performance anisotropic strontium ferrite powders for demanding motor arc magnets, radially oriented and multipole-oriented rings and cylinders, plus small, thin, or geometrically complex parts where wet pressing is impractical.
Isotropic Grades — Ba-Ferrite
| Grade | Material | Br ∥ / ⊥ (mT) | Hcb ∥ / ⊥ (kA/m) | Hcj ∥ / ⊥ (kA/m) | (BH)max ∥ / ⊥ (kJ/m³) | Shrinkage (%) | Fine Powder (μm) |
|---|---|---|---|---|---|---|---|
| SFP-D1 | BaFe₁₂O₁₉ | 200-230 / 185-205 | 129-137 / 115-125 | 199-231 / 199-231 | 7.6-8.4 / 5.6-6.4 | 14.0-16.0 | 0.8-1.0 |
| SFP-D1R | BaFe₁₂O₁₉ | 210-220 / 220-240 | 127-143 / 132-148 | 246-278 / 246-278 | 6.8-8.4 / 8.4-9.2 | 13.5-15.5 | 0.8-1.0 |
| SFP-D1A | BaFe₁₂O₁₉ | 230-240 / 195-205 | 143-151 / 123-131 | 239-271 / 239-271 | 8.4-9.2 / 5.6-6.4 | 14.0-16.0 | 0.8-1.0 |
∥ = parallel to pressing direction, ⊥ = perpendicular. SFP-D1R is optimized for rotationally-oriented (radial-field) tooling.
High-Performance Anisotropic Grades — Sr-Ferrite
| Grade | Material | Br (mT) | Hcb (kA/m) | Hcj (kA/m) | (BH)max (kJ/m³) | Shrinkage (%) | Fine Powder (μm) |
|---|---|---|---|---|---|---|---|
| SFP-D2.4 | SrFe₁₂O₁₉ | 350-370 | 207-239 | 223-255 | 22.4-25.6 | 14.5-16.5 | 0.8-0.9 |
| SFP-D2.6 | SrFe₁₂O₁₉ | ≥372 | ≥227 | ≥235 | ≥24.7 | 13.0-15.0 | 0.75-0.85 |
| SFP-D2.6H | SrFe₁₂O₁₉ | 370-380 | 245-265 | 255-279 | 23.9-25.5 | 13.0-15.0 | 0.75-0.85 |
| SFP-D2.7H | SrFe₁₂O₁₉ | ≥372 | ≥255 | ≥280 | ≥24.7 | 13.0-15.0 | 0.75-0.85 |
Anisotropic values measured parallel (∥) to the orientation field. H-suffix grades deliver enhanced intrinsic coercivity for motors subject to strong demagnetizing fields.
Key Advantages & Quality Control
✅ Particle Size Control
Laser diffraction (Malvern) analysis on every batch. D10/D50/D90 reported. Narrow Gaussian distribution for maximum packing density and consistent magnetic properties.
✅ Surface Treatment
Silane coupling agents (KH-550, KH-560) or titanate treatments available for improved polymer compatibility and melt flow in injection molding processes.
✅ Batch Consistency
Br variation ≤ ±2% batch-to-batch. Pre-sintering at 1250-1300°C ensures complete ferritization. Every batch ships with CoA (Certificate of Analysis) including XRD phase purity.
Packaging & Logistics
Standard Packaging
25 kg HDPE bags with inner moisture-barrier liner. 1,000 kg FIBC (big bags) available for bulk orders. Palletized and stretch-wrapped for ocean freight.
Global Shipping
FOB Ningbo/Shanghai. 20' FCL: ~20 MT. LCL and air freight options for trial orders. Dangerous goods documentation: not classified as hazardous for transport.
From Calcination to Consistent Powder
Ferrite powder quality is decided long before pressing — in raw-material purity, calcination profile, and milling control. Our powder lines are built around that truth.
Calcination Control
Rotary-kiln calcination with ±10°C zone control locks in the magnetoplumbite phase; every calcined lot is XRD-verified before milling.
Particle Size Discipline
Narrow PSD centered at 0.9-1.1μm via controlled ball milling — the foundation of high Br and stable pressability in your dies.
Lot-to-Lot Consistency
Magnetic property windows (Br ±0.02T, Hcj ±5%) contractualized per grade; SPC charts available for your incoming-inspection team.
Technical Partnership
Pressing trials, sintering profiles, and shrinkage data shared freely — we succeed when your pressed magnets pass first article.
Need Consistent Magnetic Powder Supply?
Tell us your binder system (PA6, PA12, epoxy, NBR rubber, HDPE) and target magnetic properties. We'll recommend the optimal powder grade and particle morphology.