Bonded ferrite-based exchange-coupled nanocomposite magnet produced by Warm compaction
Farzin Mohseni, Robert C. Pullar, Joaquim M. Vieira, João S. Amaral
Abstract
Many modern technologies require permanent magnets with combinations of properties that cannot be met by conventional metallic or ceramic magnets. Ferrite/polymer composite magnets are a type of rare-earth free magnet with a wide range of magnetic and material property combinations. The uncertainty surrounding the supply and pricing of rare-earth elements, along with environmental issues of using these elements, have motivated many researchers to develop high-performance ferrite-based magnets via an exchange spring method. The present study explores magnetite coated M-type ferrite nanocomposites synthesised via a hydrothermal and coprecipitation method, and investigates the mechanical and magnetic properties of warm compressed high-performance exchange-coupled nanocomposites in an epoxy matrix. We show how the powder-to-resin ratio and preparation conditions lead to optimised mechanical properties, and enhancement in the maximum energy product of the composite magnet by up to 120% compared to a commercial SrM bonded plasto-ferrite magnet. These high performance composite magnets can lower the final cost of ferrite based bonded magnets without reducing the permanent magnetic properties or can be used in applications that a ferrite magnet has inadequate performances.