Sintered Ferrite Magnets


High-Quality Ceramic Ferrite Industrial Magnets

Permanent ferrite magnets are also known as ceramic magnets. The first development of ferrite magnets started in the 40’s, but they have been available in the market since the 50’s.

They are obtained from iron oxides and from strontium or barium carbonate: these raw materials are plentiful on Earth, so availability of ferrite is rather high. The raw materials are mixed together, granulated, and thermally treated to get finally to the hexaferrite phase (SrFe12O19 or BaFe12O19). This granulate is then ground to a powder and strong permanent ferrite magnets are produced through a sintering process.

The Production of Permanent Ferrite Magnets

Pressing is performed under magnetic field (to maximize anisotropy of the magnet) or not (isotropic magnets) and can be wet or dry; finally, the product is sintered in an oxidizing atmosphere. Our magnets are available in both oriented (anisotropic) and non-oriented (isotropic) grades.

The great change of permanent ferrite magnets, which makes these magnets very common still today, was not the high remanence or high energy product but a reversible behavior of B versus H in the 2nd quadrant of the hysteresis loop.

The 2nd quadrant is the part of the hysteresis loop where magnets usually “work” in a device, that is where they supply energy to perform a reversible B versus H loop. This means that in such part of the loop the magnet can be partially re-magnetized or demagnetized, which usually occurs in a device without losing properties. It can be now understood the reason of ferrite success in the 50’s when only Alnico magnet, with its strongly reversible behavior, was predominant in industry.

Qualities of Ceramic Ferrite Industrial Magnets

An important peculiarity of our ceramic ferrite industrial magnets is its water resistance, being obtained from oxides. Furthermore, its coercive force dependence is very peculiar as it is increasing until 180 °C, on the contrary of all other hard magnetic materials for which coercive force strongly decreases over room temperature.

Due to this special property, we emphasize here that special care must be taken at temperatures lower than RT. Permanent ferrite magnets can be applied in a very wide range of products including:

  • electric motors
  • loudspeakers
  • sensor systems
  • instrumentation
  • toys
  • holding systems

MPI Magnets is a certified company in the production of permanent magnets, known as a leading ceramic ferrite industrial magnets manufacturer and supplier competing with the most successful international companies in the world. Our products are designed by highly qualified engineers and are developed and assembled using the most advanced technology in the market.