Differences in Raw Materials and Formulation Systems
Permanent Magnet Ferrites: Utilize SrO/BaO and Fe₂O₃ as core raw materials; formulations focus on ensuring high coercivity and remanence, with virtually no addition of soft-magnetic components such as zinc or nickel.
Soft Magnetic Ferrites: Feature Fe₂O₃ as the primary component, combined with MnO/ZnO, NiO/ZnO, or CuO/ZnO; formulation goals center on reducing high-frequency losses and enhancing magnetic permeability.
Gyromagnetic/Square-loop Ferrites:Often employ a combination of rare-earth oxides (e.g., Y₂O₃) and Fe₂O₃ to create specialized garnet-type crystal structures, meeting the specific requirements of microwave and magnetic memory applications.
Key Differences in Forming Processes
Permanent Magnet Ferrites: Predominantly manufactured using wet-pressing with a magnetic field; pressing occurs within a strong DC aligning field (60,000–80,000 ampere-turns) to orient the magnetic powder grains. This achieves an orientation degree exceeding 97%, significantly boosting the magnetic energy product.
Soft Magnetic Ferrites: Primarily formed via dry-pressing without a magnetic field (though some high-permeability products utilize isostatic pressing). No aligning field is applied; the priority is ensuring uniform core density to prevent magnetic domain anisotropy losses at high frequencies.
Bonded/Injection-Molded Ferrites: Ferrite powder is intensively mixed and granulated with polymer resins (such as nylon or PPS), then formed directly into complex shapes using injection molding machines. This process eliminates the need for high-temperature sintering, resulting in high dimensional precision and the ability to integrally mold complex, non-standard geometries.
