High Quality Y35 Ferrite Magnet for Speaker

Hard Ferrite Magnet

In contrast, Ferrite Magnet 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 Permanent Ferrite Magnet.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. Strontium hexaferrite (SrFe12O19) is well known for its high coercivity due to its magnetocrystalline anisotropy. It has been widely used in industrial applications as permanent magnets and, because they can be powdered and formed easily, they are finding their applications into micro and nano-types systems such as biomarkers, bio diagnostics and biosensors.

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.   

Hard ferrites have high coercivity, so are difficult to demagnetize. They are used to make permanent magnets for applications such as refrigerator magnets, loudspeakers, and small electric motors.

Isotropic Magnets:

Isotropic magnets include bond magnets using quick-cooled thin alloy as the raw material and Isotropic Ferrite Magnets, but their magnetic characteristics are inferior to those of anisotropic magnets. Rare earth sintered magnets can not be made isotropic.

The main performance and grade parameters of Isotropic Ferrite Magnets and Anisotropic Ferrite Magnets