Ferrite is divided into soft ferrite and permanent ferrite.
soft ferrite
There are manganese ferrite (MnO Fe2O3), zinc ferrite (ZnO Fe2O3), nickel zinc ferrite (Ni-Zn Fe2O4), manganese magnesium zinc ferrite (Mn-Mg-Zn Fe2O4), etc. One-component or multi-component ferrites. The resistivity is much larger than that of metal magnetic materials, and it has higher dielectric properties, so ferrites with both ferromagnetism and ferroelectricity as well as ferromagnetism and piezoelectricity appear. It has a much higher magnetic permeability than metal magnetic materials (including iron-nickel alloys, aluminum-silicon-iron alloys) at high frequencies, and is suitable for working at frequencies from several kilohertz to several hundred megahertz. Processing ferrite belongs to the general ceramic process, so the process is simple, and a lot of precious metals are saved, and the cost is low. The saturation magnetic flux density Bs of ferrite is low, usually only 1/3 to 1/5 of iron. The low magnetic energy stored in the unit volume of ferrite limits its application in low frequency, high power and high power fields that require higher magnetic energy density. It is more suitable for high frequency, low power, and weak current applications. Nickel-zinc ferrites can be used as antenna rods and intermediate frequency transformer cores in radios, and manganese-zinc ferrites can be used as line output transformer cores in TV receivers. In addition, soft ferrite is also used in inductors and filter cores in communication lines. In recent years, it has also been used as a high-frequency magnetic recording transducer (magnetic head).
Permanent magnet
with barium ferrite
(BaO·6Fe2O3) and strontium ferrite (SrO·6Fe2O3). It has high resistivity and belongs to the semiconductor type, so the eddy current loss is small and the coercive force is large. It can be effectively used in the magnetic circuit of the large air gap, and is especially suitable for the permanent magnet of small generators and motors. It does not contain precious metals such as nickel and cobalt, has abundant raw material sources, uncomplicated process and low cost, and can replace AlNiCo permanent magnets. Its maximum magnetic energy product (B+H)m is lower, so it is larger than metal magnets under the same magnetic energy. Its temperature stability is poor, its texture is brittle and fragile, and it is not resistant to shock and vibration. It is not suitable for measuring instruments and magnetic devices with precision requirements. Permanent magnet ferrite products are mainly anisotropic series. They can be used to make permanent magnet ignition motors, permanent magnet motors, permanent magnet concentrators, permanent magnet lifting heads, magnetic thrust bearings, magnetic separators, speakers, microwave devices, magnetic therapy tablets, hearing aids, etc.
There are manganese ferrite (MnO Fe2O3), zinc ferrite (ZnO Fe2O3), nickel zinc ferrite (Ni-Zn Fe2O4), manganese magnesium zinc ferrite (Mn-Mg-Zn Fe2O4), etc. One-component or multi-component ferrites. The resistivity is much larger than that of metal magnetic materials, and it has higher dielectric properties, so ferrites with both ferromagnetism and ferroelectricity as well as ferromagnetism and piezoelectricity appear. It has a much higher magnetic permeability than metal magnetic materials (including iron-nickel alloys, aluminum-silicon-iron alloys) at high frequencies, and is suitable for working at frequencies from several kilohertz to several hundred megahertz. Processing ferrite belongs to the general ceramic process, so the process is simple, and a lot of precious metals are saved, and the cost is low. The saturation magnetic flux density Bs of ferrite is low, usually only 1/3 to 1/5 of iron. The low magnetic energy stored in the unit volume of ferrite limits its application in low frequency, high power and high power fields that require higher magnetic energy density. It is more suitable for high frequency, low power, and weak current applications. Nickel-zinc ferrites can be used as antenna rods and intermediate frequency transformer cores in radios, and manganese-zinc ferrites can be used as line output transformer cores in TV receivers. In addition, soft ferrite is also used in inductors and filter cores in communication lines. In recent years, it has also been used as a high-frequency magnetic recording transducer (magnetic head).
Permanent magnet
with barium ferrite
(BaO·6Fe2O3) and strontium ferrite (SrO·6Fe2O3). It has high resistivity and belongs to the semiconductor type, so the eddy current loss is small and the coercive force is large. It can be effectively used in the magnetic circuit of the large air gap, and is especially suitable for the permanent magnet of small generators and motors. It does not contain precious metals such as nickel and cobalt, has abundant raw material sources, uncomplicated process and low cost, and can replace AlNiCo permanent magnets. Its maximum magnetic energy product (B+H)m is lower, so it is larger than metal magnets under the same magnetic energy. Its temperature stability is poor, its texture is brittle and fragile, and it is not resistant to shock and vibration. It is not suitable for measuring instruments and magnetic devices with precision requirements. Permanent magnet ferrite products are mainly anisotropic series. They can be used to make permanent magnet ignition motors, permanent magnet motors, permanent magnet concentrators, permanent magnet lifting heads, magnetic thrust bearings, magnetic separators, speakers, microwave devices, magnetic therapy tablets, hearing aids, etc.