Al-ni-co permanent magnet material for motor magnets is the earliest and most widely used permanent magnet material, and its preparation technology and process are relatively mature. Now there are factories in Japan, America, Europe, Russia, China. Among large production enterprises, Hangzhou ranks first in the output of permanent magnets in China, with an annual output of 3,000 tons.
Permanent magnet ferrite materials: Into the 1950s, ferrite began to flourish. Especially in the 1970s, strontium ferrites with good coercivity and magnetic energy machine performance were produced in large quantities, and the use of permanent magnet ferrites expanded rapidly. As a kind of non-metallic magnetic material, ferrite is favored because of its easy oxidation, low Curie temperature and high cost.
Samarium cobalt: A permanent magnet material developed in the mid 1960s with excellent magnetic properties and very stable properties. As far as magnetism is concerned, samarium cobalt is particularly suitable for the manufacture of electric motors. But because of the high price, mainly used in aviation, aerospace, weapons and other military motor research and development, as well as high performance, high price is not the main factor of high-tech motor.
Ndfeb material (NdFeb magnetic material is an alloy of neodymium and iron oxide, also known as magnetic steel. It has very high magnetic energy product and coercive magnetic force. At the same time, the advantage of high energy density makes ndFeb permanent magnet material widely used in modern industry and electronic technology, making it possible to miniaturize, lightweight and thin shape of instruments, electroacoustic motors and magnetic separation magnetization equipment. Because it contains a lot of neodymium and iron, so easy to rust. Surface chemical passivation is one of the better solutions.
Ferromagnetic materials commonly used in motor magnets are generally divided into non-ferromagnetic materials and ferromagnetic materials according to their permeability. Due to the low permeability of non-ferromagnetic materials, they exhibit the non-permeability of air, copper, aluminum, insulating materials, etc. While ferromagnetic materials show high permeability, they show good permeability of iron, nickel, cobalt and their alloys. It is through a certain excitation in the motor magnetomotive force to produce a strong magnetic field. Magnetic circuit is made of strong magnetic material with high permeability.
The magnetization of motor magnet materials refers to the application of magnetic field on ferromagnetic materials. The magnetic field in the material is significantly enhanced, showing a strong magnetic field. This phenomenon is that ferromagnetic materials are magnetized. Ferromagnets magnetize because they have many small magnet-like regions inside them. Magnetic domains are represented by small magnets with magnetic properties. This material is not affected by external magnetic fields. The domains are chaotic, their magnetic effects cancel each other out, and there is no external magnetism. Once applied to an external magnetic field, the domains resist rotational frictional resistance, and the magnetic axes rotate uniformly, resulting in an additional magnetic field superimposed on the external field, and the resultant field is greatly enhanced. The results show that since there are no magnetic domains in the internal structure of non-ferromagnetic materials, there is no magnetization. So under the same magnetic field, the magnetic field excited by ferromagnetic materials is very strong, and the permeability of ferromagnetic materials is much higher than that of non-ferromagnetic materials.
