Ferrite is a term used to refer to pure iron, the most easily recognisable ferromagnetic material. It is also a term used to describe ferrite magnetic material which is a compound consisting of strontium carbonate or barium and iron oxide (Fe2O3). Ferrite magnets have low production costs but are also much weaker than rare earth samarium cobalt and neodymium magnets. Because of their low production costs they are one of the most widely used magnetic materials when high magnetic performance is not the most important factor. The method for producing ferrite magnets is not as costly or sophisticated as that for manufacturing rare earth magnets and because they are very hard and brittle they are generally manufactured in basic shapes such as squares, cylinders and rings. The production of ferrite magnets begins with calcining a finely powdered mixture of iron oxide and strontium carbonate to produce a metallic-oxide material. Once cooled, the already fine powder is then milled a number of times reducing the calcined material to fine particles smaller than 2 micrometres or 2 microns, so that each particle consists of one single magnetic domain. The powder is then pressed and compacted into a die. If pressing takes place within an externally applied magnetic field the magnet's particles will be aligned and the magnet produced will be anisotropic. If the powder is pressed without an externally applied magnetic field the magnet will be isotropic and have weaker magnetic properties. Once pressed, the compacted particles are then sintered at very high temperatures to make the particles fuse together before finally being magnetised.
Magnetic Properties
Ferrite magnets are inexpensive to produce which is relative to their overall magnetic strength. Despite being significantly weaker than rare earth materials they are still widely used in many commercial applications. The main strength of ferrite magnets is their resistance to demagnetisation and corrosion.
