Sintered Ferrite Magnet
, hard ferrite, hard ferrite magnet is also called Ceramic Magnets.
Sintered ferrite magnets are available in isotropic magnet and anisotropic magnets. The magnetic properties of isotropic ferrite are low. Since they have nearly the same magnetic properties in all directions, so isotropic ferrite magnets can be magnetized in many different directions or in multi-poles. Anisotropic ferrite magnets have better magnetic properties compare with isotropic ferrite magnets. However this type of magnets can only be magnetized along a preferred direction.
Permanent ferrite magnets are made of hard ferrites, which have a high coercivity and high remanence after magnetization. Iron oxide and barium or strontium carbonate are used in manufacturing of hard ferrite magnets. The high coercivity means the materials are very resistant to becoming demagnetized, an essential characteristic for a permanent magnet. They also have high magnetic permeability. These so-called ceramic magnets are cheap, and are widely used in household products such as refrigerator magnets. The maximum magnetic field B is about 0.35 tesla and the magnetic field strength H is about 30 to 160 kiloampere turns per meter (400 to 2000 oersteds). The density of ferrite magnets is about 5 g/cm3.
The most common hard ferrites are:
Strontium ferrite, SrFe12O19 (SrO·6Fe2O3), used in small electric motors, micro-wave devices, recording media, magneto-optic media, telecommunication and electronic industry.
Barium ferrite, BaFe12O19 (BaO·6Fe2O3), a common material for permanent magnet applications. Barium ferrites are robust ceramics that are generally stable to moisture and corrosion-resistant. They are used in e.g. loudspeaker magnets and as a medium for magnetic recording, e.g. on magnetic stripe cards.
Why choose Ferrite Magnet?
1. Low cost and low price.
The raw material cost is very cheap and manufacturing process is simple. So the price if it is very low.
2. Nice temperature stability
Ferrite magnets can be used in the working temperature from -40℃ to 200℃.
3. Well prevent corrosion
The raw material of sintered ferrite magnet is oxide, so ferrite magnets will not be rusted under severe environment nor affected by many chemicals.