Classification of Magnetic Materials
Magnetic materials refer to substances composed of transition elements iron, cobalt, nickel and their alloys that can directly or indirectly generate magnetism. Magnetic materials have different classification standards: according to material and structure, magnetic materials include metals and alloys. Magnetic materials and iron Oxygen magnetic materials are divided into two categories, among which ferrite magnetic materials are further divided into polycrystalline structure and single crystal structure materials. But our commonly used classification is divided according to function, mainly including permanent magnetic materials, soft magnetic materials and functional magnetic materials. Among them, permanent magnetic materials and soft magnetic materials include both metals and ferrites. Functional magnetic materials mainly include magnetostrictive materials, magnetic recording materials, magnetoresistive materials, magnetic bubble materials, magneto-optical materials, and gyromagnetic materials. materials and magnetic film materials.
Classification of Magnetic Materials
Permanent magnet material
Permanent magnet materials, also known as “hard magnetic materials”, refer to materials that can maintain constant magnetism once magnetized. In practice, permanent magnet materials work in the second quadrant demagnetization part of the deep magnetic saturation and hysteresis loop after magnetization .High carbon steel, AlNiCo alloy, FeCrCo alloy, Samarium Cobalt alloy, etc. are all permanent magnet materials. They can be used to make permanent magnets and provide a constant working magnetic field in a certain space. Using itself or through the magnetic field and The interaction of current-carrying conductors, charged particles and eddy currents can easily exchange one kind of energy for another, so it is widely used in various precision instruments, electroacoustic devices, permanent magnet motors, microwave devices, and nuclear magnetic resonance imaging. instrument, particle accelerator, magnetic coupling rotating device and various magnetic therapy devices.
soft magnetic material
Soft magnetic material refers to when the magnetization occurs at Hc not greater than 1000A/m, such a material is called a soft magnet. A typical soft magnetic material can achieve the maximum magnetization with the smallest external magnetic field. Soft magnetic materials are magnetic materials with low coercivity and high permeability. Soft magnetic materials are easy to magnetize and easy to demagnetize, and are widely used in electrical and electronic equipment. Typical soft magnetic materials include pure iron, silicon steel, nickel-iron alloy, iron-cobalt alloy, manganese-zinc ferrite, etc.
Gyromagnetic material
Gyromagnetic materials exhibit significant gyromagnetic phenomena at microwave frequencies, such as rotating the plane of polarization of electromagnetic waves passing through them (Faraday’s law of geomagnetic induction), or decomposing incident electromagnetic waves into lines with different propagation speeds and perpendicular to each other Polarized waves (law of birefringence) or electromagnetic waves are strongly absorbed by materials (ferromagnetic resonance). Various microwave ferrite devices can be made by using philosophical gyromagnetic phenomena, such as isolators, circulators, phase shifters, mixers, Parametric amplifiers, etc., are widely used in radar technology. Typical materials are spinel ferrite represented by magnesium manganese and lithium ferrite, garnet ferrite represented by yttrium iron garnet, and barium ferrite represented by Ferrite is represented by magnetoplumbite ferrite, etc.
Magnetic information material
Magnetic information materials refer to a large class of magnetic materials used in computers, magnetic recording and other information processing technologies to access information. With the development and popularization of computers and video recorders, the output value of such magnetic information materials has always been the highest among magnetic materials. tallest.
There are three main series of measurement indicators for the performance of magnetic materials:
(1) Stability, the main parameters are residual magnetization, maximum magnetic energy product, the higher the value, the higher the magnetic field strength, the better the magnet can maintain its own magnetic properties;
(2) Anti-demagnetization, the main parameter is the intrinsic coercivity, the larger the value, the stronger the anti-demagnetization ability and the higher the use efficiency;
(3) Temperature resistance, the main parameters are intrinsic coercivity, maximum use temperature and Curie temperature. The higher the value, the better the temperature resistance and the more stable the performance of the magnetic material.