Common permanent magnet materials are AlNiCo, ferrite permanent magnet materials and rare earth permanent magnet materials.
Alnico-cobalt alloys have been developed from Al-Ni-Fe alloys. At present, the types of Al-N-cobalt alloys that can be manufactured in China are mainly LNG34, LNG52, LNGJ32, LNGJ56 and so on.
Since the main characteristic of AlNiCo is high Br (residual magnetic induction) and low coercive permanent magnet materials, the relative magnetic permeability is above 3, so in the specific application, the magnetic pole must be a growth cylinder or a long rod. Body to minimize the effect of demagnetization.
The AlNiCo magnet has a low coercive force. Therefore, any iron device should be strictly prohibited from contacting the AlNiCo permanent magnet material during use to avoid local demagnetization of the permanent magnet and distortion of the magnetic flux distribution in the magnetic circuit.
The advantage of the AlNiCo magnet is that the temperature coefficient is small, and the deterioration of the permanent magnet characteristics due to temperature changes is small, but the material is hard and brittle, and processing is difficult.
The main applications of AlNiCo are in electronic ignition systems, watt-hour meters, voltammeters, medical instruments, industrial motors, magnetic reed switches, generators, hand tools, vending machines, etc. Ferrite permanent magnet material is one of the most widely used permanent magnet materials, and its main component is MoFe2O3.
It has the advantages of large coercive force, light weight, abundant raw material source, low price, oxidation resistance, corrosion resistance, large anisotropy constant of magnetic crystal, and approximate demagnetization curve as straight line.
The disadvantage is that the residual magnetism is low, the temperature coefficient is large, and it is brittle.
The coercive force of the ferrite permanent magnet material is between the AlNiCo material and the rare earth cobalt permanent magnet material, and is generally suitable for being designed into a flat shape because of its low remanence.
Due to its low cost, ferrite magnetic materials have a wide range of applications, from motors and speakers to toys and handicrafts, making them the most widely used permanent magnet materials.
The rare earth permanent magnet material has the advantages of high coercive force, large maximum magnetic energy product, and reversible magnetic permeability equal to one.
Therefore, its magnetic properties far exceed that of other magnetic materials such as ferrite and aluminum nickel cobalt.
The appearance of rare earth permanent magnet materials has made the permanent magnet synchronous motors with light weight and small volume successively come out, thus expanding the application range of permanent magnet synchronous motors.
Rare earth cobalt permanent magnet materials have excellent performance, but the price is high, so it must be carefully calculated in the design, and strive to achieve the desired effect with the smallest volume.
Since the rare earth cobalt permanent magnet material has a large coercive force, it can be made into a thin-plate permanent magnet material to reduce the volume and save materials. Commonly used rare earth permanent magnet materials are SmPrCo, SmCoPeCo, SmPrNdCo, CeCoCuFe, Sm2Co17 and the like.