AlNiCo Magnets 20160705

AlNiCo Magnets 20160705
Cast or Sintered AlNiCo Permanent Magnets

China Rare Earth Magnet Limited supplies all kinds of alnico permanent magnets

We'd like to introduce the main features of alnico magnet.

The change of the magnetism of alnico magnet with the temperature change is very small.

They are still widely used in instruments and meters, electrical machinery products and permanent magnet devices which have requirements of high temperature stability, particularly suitable for torpedoes, missiles, aircraft and other weapons and equipments used in spacecraft and satellites, etc. The residual magnetic flux density of this material is relatively higher, up to 1.35 T, but their intrinsic coercive force is very low, typically less than 160 kA/m, its demagnetization curve is nonlinear variation, and the recoil line of alnico is misalignment with the demagnetization curve, so during the magnetic circuit design and manufacture of the device, we should pay special attention to its particularity, the treatment of the magnetism stability of permanent magnet must be proceeded in advance. According to the low coercive force characteristics of alnico, it is strictly prohibited in contact with any of the ferromagnetic material in use, so as not to cause irreversible demagnetization of local or distortion of the distribution of magnetic flux density. In addition, in order to strengthen its ability of resistance to demagnetization, the magnetic pole faces of Alnico rare earth magnets are often designed in shape of cylinder or long bar.

Moreover, alnico magnets are low in mechanical strength, high in hardness, brittle in material and poor in machinability, therefore they cannot be used as structure design, a bit of grinding or electro sparking are allowed in processing, and the forging and other machining cannot be adopted.

 Alnico permanent magnet is one of the first widely used magnetic materials, the preparation technology and manufacturing technology is comparative mature.

The following table shows the commonly used grade and the main magnetic properties of domestic produced alnico material.

The outstanding features of alnico magnetic material are listed as follows:
(1) temperature coefficient is small, the remanent magnetization reversible temperature coefficient alpha Br was only about 0.02% / ℃ or so, coercive force reversible temperature coefficient is about + 0.015% / ℃;
(2) Superior corrosion resistance ability;
(3) The Curie temperature as high as 860 ℃, and the applicable temperature is up to 550 ℃.