Permanent Magnets Based on Hard Ferrite Ceramics

• Cecilia Granados-Miralles ^[1] ; Matilde Saura-Múzquiz ^[2] ; Andersen, Henrik L. ^[2]
  1. [1] Instituto de Cerámica y Vidrio

     Instituto de Cerámica y Vidrio

     Madrid, España

     
  2. [2] Universidad Complutense de Madrid

     Universidad Complutense de Madrid

     Madrid, España

     
• Localización: Ceramic Materials: Present and Future / coord. por Amparo Borrell Tomás, Rut Benavente Martínez, 2023, ISBN 978-1-83634-016-4, págs. 67-88
• Idioma: inglés
• Enlaces
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• Resumen

  • Permanent magnets are integral components in many of the modern technologies that are critical for the transition to a sustainable society. However, most of the high-performance (BHmax > 100 kJ/m3) permanent magnets that are currently employed contain rare earth elements (REE), which have long been classified as critical materials with a high supply risk and concerns regarding pollution in their mining. Therefore, suitable REE-lean/free magnets must be developed in order to ensure the sustainability of clean energy generation and electric mobility. The REE-free hexagonal ferrites (or hexaferrites) are the most used permanent magnets across all applications, with an 85 wt.% pie of the permanent magnet market. They are the dominant lower-grade option (BHmax < 25 kJ/m3) due to their relatively good hard magnetic properties, high Curie temperature (>700 K), low cost and good chemical stability. In recent years, the hexaferrites have also emerged as candidates for substituting REE-based permanent magnets in applications requiring intermediate magnetic performance (25–100 kJ/m3), due to considerable performance improvements achieved through chemical tuning, nanostructuring and compaction/sintering optimization. This chapter reviews the state-of-the-art sintering strategies being investigated with the aim of manufacturing hexaferrite magnets with optimized magnetic properties, identifying key challenges and highlighting the natural future steps to be followed.