AlNiCo is the first to develop a permanent magnetic material, is composed of aluminum, nickel, cobalt, iron and other trace elements of an alloy. Aluminum-nickel-cobalt permanent magnet material was developed in the 1930s. At that time, its magnetic properties of the best, the temperature coefficient is small, and thus in the permanent magnet motor used in the most and most extensive. After 60 years, with the ferrite permanent magnet and rare earth permanent magnet have come out, aluminum nickel cobalt permanent magnet in the motor application gradually replaced, the proportion of a downward trend.
According to the production process is divided into sintered aluminum nickel cobalt (Sintered AlNiCo) and cast aluminum nickel cobalt (Cast AlNiCo). Product shapes are mostly round and square. The sintered product is limited to a small size, and the roughness tolerances produced by the casting process are better than those of the foundry product, and the magnetic properties are slightly lower than those of the foundry product, but the sintered product is limited to a small size. Processing is better. In permanent magnet materials, cast aluminum nickel cobalt permanent magnet has a minimum reversible temperature coefficient, the working temperature can be as high as 600 degrees Celsius. Alnico permanent magnet products are widely used in a variety of instrumentation and other applications.
The advantages of aluminum-nickel-cobalt-based magnets are high remanence (up to 1.35T) and low temperature coefficient. In the temperature coefficient of -0.02% / ℃, the maximum temperature of up to 520 ℃ or so. The disadvantage is that the coercive force is very low (usually less than 160 kA / m), and the demagnetization curve is nonlinear. Therefore, although the alnico magnet is easily magnetized, it is also easy to demagnetize.
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