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Ferrite magnet is a ceramic material and consists of agglomerated crystalline domains with spinel structure. Like other ceramic materials, ferrite magnets are brittle. For example, here is a photo of newly manufactured $\ce{Sr_xBa_{1-x}FeO2}$ tablet which already has chips and sharp fragments stuck on a surface:

ferrite magnets should be handled delicately

This is one of the primary reasons as to why ferrite magnets for the consumer market are sold wrapped in plastic shells or coated with resin. There are also flexible magnets, a composite material consisting of a polymer matrix impregnated with ferrite magnet powder. Flexible magnets do not crumble and are more impact-resistant, but they are also significantly weaker due to lower density of magnetic domains.

Would it be possible to do the opposite, i.e. impregnate the ferrite ceramic body with polymer to create a less brittle composite material still retaining magnetic properties comparable with those of a bulk permanent magnet?

I suppose the main difficulty stems from the fact that the manufacturing technology requires sintering at the temperatures around 1000 °C which limits the variety of binders and polymers to choose from. If there is no alternatives to currently used inorganic salts, can the impregnation be done afterwards? One suggestion could be creation of a slight increase in porosity of ferrite and filling the voids with polymer in vacuo at lower temperatures, but I didn't find any sources as to how legitimate or cost-efficient this approach can be.

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    $\begingroup$ Organic polymers like the ones to create the VHS K7 will have difficulties to sustain temperatures above 300 C. Do you need to retain their mechanical flexibility? What magnetic strength should these provide, still like the bulk ferrite ones, or would something as week as the tapes suffice? Blending the concept of magnets with a head resistant matrix ... the ceramic tiles of Buran spacecraft, or lightweight aeorogels an early example ... just some thoughts. $\endgroup$
    – Buttonwood
    Commented Feb 14, 2021 at 17:13
  • $\begingroup$ @Buttonwood Thank you for additional examples with the tape and space shuttle. Basically, what I have in mind is a solid bulk ferrite reinforced with polymer to reduce brittleness. Sounds quite simple on paper IMO, but I didn't find anything related despite an existing demand for a material like that. $\endgroup$
    – andselisk
    Commented Feb 14, 2021 at 17:19
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    $\begingroup$ By their nature, highly magnentic materials are brittle, and inducing porosity decreases magnetic strength. "Rare-earth" magnets are usually plated with a malleable metal to reduce shattering, somewhat. Iron pole-pieces may be cemented to ferrite magnets for the same purpose. $\endgroup$ Commented Feb 14, 2021 at 19:26

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I would suggest soft metals mixed with the ferrite. Nickel, Cobalt, Iron, Nickel-Iron alloy. Study well the phase diagram and consider equipment and process to control and leverage the boundaries to produce your ideal magnet

For polymer formulations use nano powders of the magnetic materials because the surface area and density may be better controlled and tuned to the strength you desire.

Especially with polymer formulations as the polymer cures, apply a strong magnetic field across the piece to align the ferrite particles and induced metal particles. This will help significantly to improve the field line concentration.

Your pulling the Ferrite apart to form individual atoms and linking them into a flexible matrix with the maximum magnetic dipole field lines density. The nano powder composite is a close comparison.

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  • $\begingroup$ I assume the OP means treating already made magnets. $\endgroup$
    – Poutnik
    Commented Jun 21 at 16:13

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