Advanced Flash Sintering Approaches for Synthesizing and sintering SrFe12O19 hexaferrite ceramic magnets

Hexagonal ferrites, particularly strontium ferrite (SrFe₁₂O₁₉), are among the most promising candidates for the partial substitution of rare-earth-based permanent magnets. While they have been successfully implemented in various applications, the fabrication of dense SrFe₁₂O₁₉ components with optimal magnetic properties remains a major challenge. Conventional sintering techniques often require prolonged high-temperature treatments, leading to significant grain growth and consequent deterioration of coercivity—an essential property for magnet performance.

In this study, we explore the use of advanced flash sintering techniques to overcome these limitations. Flash sintering, a rapidly growing field within the FAST (Field-Assisted Sintering Technology) family, enables dramatic reductions in processing time and temperature, offering a more sustainable route for ceramic fabrication. We report on the successful synthesis of SrFe₁₂O₁₉ using three distinct flash-based methods: reactive flash sintering (1), multiphase-reactive flash sintering (2), and touch-free flash sintering (3). These approaches not only improve densification kinetics but also help retain fine microstructures that are critical for high coercivity.

Our results highlight the strong potential of flash techniques for scalable, energy-efficient production of high-performance SrFe₁₂O₁₉ magnets, paving the way for broader industrial adoption of rare-earth-free magnetic materials.

References

[1] A.F. Manchón-Gordón et al. Reactive flash Sintering of SrFe12O19 ceramic permanent magnets, Journal of Alloys and Compounds 922 (2022) 166203.

[2] A.F. Manchón et al. Expanding the scope of multiphase-flash Sintering: Multi-dogbone configurations and reactive processes. Ceramic International 50 (2024) 25210-25215

[3] Syed I.A. Jalali, et al. Touch-free reactive flash sintering of dense strontium hexaferrite permanent magnet Journal of the American Ceramic Society 106 (2023) 7202-7208