Common permanent magnet materials
are Al-Ni-Co alloy, ferrite permanent magnet materials and rare earth permanent magnet materials. Al-Ni-Co alloys are developed from Al-Ni-Fe alloys. At present, the main types of Al-Ni-Co alloys that can be manufactured in my country are LNG34, LNG52, LNGJ32, LNGJ56, etc. Since the main feature of AlNiCo is a permanent magnetic material with high Br (residual magnetic induction) and low coercivity, its relative permeability is above 3, so in specific applications, its magnetic poles must be made as long cylinders or long rods Body to minimize the effect of demagnetization. Alnico magnets have low coercivity, so any iron should be strictly prohibited from contacting Alnico permanent magnet materials during use to avoid local demagnetization of permanent magnets and distortion of the magnetic flux distribution in the magnetic circuit. The advantage of AlNiCo magnets is that the temperature coefficient is small, and the deterioration of the permanent magnetic properties due to temperature changes is also 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 and other fields. 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 high coercivity, light weight, abundant raw materials, low price, oxidation resistance, corrosion resistance, large anisotropy constant of magnetic crystal, and the demagnetization curve is approximately a straight line. The disadvantage is that the remanence is low, the temperature coefficient is large, and it is fragile. The coercivity of ferrite permanent magnet materials is between that of AlNiCo alloy materials and rare earth cobalt permanent magnet materials. Because of its low remanence, it is generally suitable to be designed into a flat shape. Due to its low cost, ferrite magnets have a wide range of applications, from motors and speakers to toys and handicrafts, so they are currently the most widely used permanent magnet materials. Rare earth permanent magnetic materials have the advantages of high coercivity, large maximum magnetic energy product, and reversible permeability equal to one. Therefore, its magnetic properties far exceed other magnetic materials such as ferrite and AlNiCo.
The emergence of rare earth permanent magnet materials has led to the emergence of light weight and small permanent magnet synchronous motors, thereby expanding the application range of permanent magnet synchronous motors. Rare earth cobalt permanent magnet materials have excellent performance, but the price is relatively high, so careful calculations must be made in the design, and strive to achieve the desired effect with the smallest volume. Due to the high coercivity of rare earth cobalt permanent magnet materials, it can be made into thin permanent magnet materials to reduce the volume and save materials. Common rare earth permanent magnet materials include SmPrCo, SmCoPeCo, SmPrNdCo, CeCoCuFe, Sm2Co17, etc.