What are magnets?
The composition of the magnet is iron, cobalt, nickel and other atoms, the internal structure of the atom is relatively special, it has magnetic moment itself. Magnets can produce magnetic fields and have the characteristics of attracting ferromagnetic materials such as iron, nickel, cobalt and other metals.
What is a permanent magnet?
Permanent magnets are permanent magnets, which can be natural minerals, also known as natural magnets, or they can be manufactured artificially (the strongest magnets are neodymium iron boron magnets). It is a material with wide hysteresis loop, high coercivity, high remanence, and can maintain constant magnetic properties once magnetized. Also known as permanent magnetic materials, hard magnetic materials. In application, the permanent magnet works in the demagnetization part of the second quadrant of the magnetic Ray loop after deep magnetic saturation and magnetization. The permanent magnet should have the highest possible coercivity Hc, remanence Br and the maximum magnetic energy product (BH) m to ensure the storage of maximum magnetic energy and stable magnetism.
Classification of permanent magnets
Classified by material
- (1) Alloy permanent magnet materials: including rare earth permanent magnet materials (NdFeB Nd2Fe14B), Samarium Cobalt (SmCo), Aluminum Nickel Cobalt (AlNiCo).
- (2) Ferrite permanent magnet material (Ferrite).
Classified by production process
According to different production processes, it is divided into: sintered ferrite, bonded ferrite, and injection molded ferrite. These three processes are divided into isotropic and anisotropic magnets according to the orientation of the magnetic crystal.
The above are the main permanent magnet materials currently on the market, and some are eliminated due to production process or cost reasons, which cannot be used in a wide range, such as Cu-Ni-Fe (copper nickel iron), Fe-Co-Mo (iron cobalt molybdenum) ), Fe-Co-V (iron cobalt vanadium), MnBi (manganese bismuth).
Type of magnet
- Shape magnet: square magnet, tile magnet, shaped magnet, cylindrical magnet, ring magnet, disc magnet, magnetic rod magnet, magnetic frame magnet;
- Attribute magnet: SmCo magnet, NdFeB magnet (strong magnet), ferrite magnet, Al Ni Co magnet, Fe Cr co magnet;
- Industry magnet: magnetic components, motor magnet, rubber magnet, plastic magnet Magnetism and so on.
Magnets are divided into permanent magnets and soft magnets. Permanent magnets add strong magnetism to make the spin of magnetic materials and the angular momentum of electrons in a fixed direction, while soft magnets add electricity. (also a method of adding magnetic force) when the soft iron is removed by equal current, the magnetism will gradually lose.
Hang the middle point of the bar magnet with a thin line. When it is still, its two ends will point to the South and north of the earth. The end pointing to the north is called the north pole or N pole, and the end pointing to the south is the guide pole or S pole.
If we think of the earth as a big magnet, the geomagnetic north pole of the earth refers to the south pole, and the geomagnetic South Pole refers to the North Pole. Between magnets, the magnetic poles of the same name repel each other and attract the other. Therefore, the compass repels the south pole, the North Pole repels, and the compass and compass attract.
Mainstream permanent magnet
Rare earth permanent magnet materials
Rare earth permanent magnet materials (NdFeB, Nd2Fe14B) are divided into the following three types according to different production processes:
Bonded NdFeB is a composite NdFeB permanent magnet made by uniformly mixing NdFeB powder with resin, plastic or low melting point metal and other binders, and then using compression, extrusion or injection molding methods. The product is formed once without secondary processing, and can be directly formed into various complex shapes. Bonded NdFeB has magnetism in all directions and can be processed into NdFeB compression molds and injection molds. High precision, excellent magnetic properties, good corrosion resistance and good temperature stability.
Sintered neodymium iron boron permanent magnets are smelted after airflow milling. They have high coercivity and extremely high magnetic properties. Its maximum magnetic energy product (BHmax) is more than 10 times higher than that of ferrite. Its own mechanical properties are also quite good, it can cut and process different shapes and drill holes. The maximum working temperature of high-performance products can reach 200℃.
Because of its material content, it is easy to cause corrosion, so the surface must be treated with different coatings according to different requirements. (Such as zinc, nickel, environmentally friendly zinc, environmentally friendly nickel, nickel copper nickel, environmentally friendly nickel copper nickel, etc.). Very hard and brittle, with high resistance to demagnetization, high cost/performance ratio, not suitable for high working temperature (>200℃).
Injection molded neodymium iron boron
It has extremely high accuracy and is easy to make thin-walled rings or thin magnets with complex anisotropic shapes.
The main raw materials of sintered ferrite include BaFe12019 and SrFe12019, which are divided into isotropic and anisotropic magnets according to the orientation of the magnetic crystal.
Because of its low price and moderate magnetic properties, it has become a widely used magnet at present. Ferrite magnets are manufactured by ceramic technology, and the texture is relatively hard, and it is also a brittle material. Due to its good temperature resistance and low price, ferrite magnets have become more widely used permanent magnets.
Rubber Magnet (Rubber Magnet) is one of the ferrite magnetic material series. It is made of bonded ferrite powder and synthetic rubber through extrusion molding, calendering molding, injection molding and other processes. Flexible and twistable magnet. It can be processed into strips, rolls, flakes and various complex shapes. Rubber magnets are made of magnetic powder (SrO6Fe2O3), polyethylene (CPE) and other additives (EBSO, DOP), etc., and are manufactured by extrusion and calendering. The rubber magnetic material can be of the same sex or the opposite sex. It is made of ferrite magnetic powder, CPE and some trace elements, and can be bent, twisted and rolled. It can be used without more mechanical processing, and the shape can be trimmed to the required size. The rubber magnet can also be compounded with PVC, back glue, UV oil, etc. according to customer requirements. Its magnetic energy product is between 0.60 and 1.50 MGOe. Application areas of rubber magnetic materials: refrigerators, information signage racks, fasteners for fixing objects to metal bodies for advertising, etc., magnetic sheets for toys, teaching instruments, switches, and sensors. Mainly used in micro-motors, refrigerators, disinfection cabinets, kitchen cabinets, toys, stationery, advertising and other industries.
Aluminum Nickel Cobalt (AlNiCo) is the first permanent magnet material developed. It is an alloy composed of aluminum, nickel, cobalt, iron and other trace metal elements. According to different production processes, it is divided into sintered aluminum nickel cobalt (Sintered AlNiCo) and cast aluminum nickel cobalt (Cast AlNiCo). The product shapes are mostly round and square. The casting process can be processed into different sizes and shapes; compared with the casting process, sintered products are limited to small sizes, and the produced blanks have better dimensional tolerances than cast products, and their magnetic properties are slightly lower than cast products, but they can Workability is better. Among the permanent magnet materials, cast AlNiCo permanent magnets have the lowest reversible temperature coefficient, and the working temperature can be as high as 600℃. Alnico permanent magnet products are widely used in various instruments and other applications.
Samarium cobalt (SmCo) is divided into SmCo5 and Sm2Co17 according to the composition, which are the first and second generation rare earth permanent magnet materials respectively. Because its raw materials are very scarce and expensive, its development is restricted. Samarium cobalt (SmCo), as the second-generation rare earth permanent magnet, not only has a high magnetic energy product (14-28MGOe) and reliable coercivity, but also shows good temperature characteristics in the rare earth permanent magnet series. Compared with NdFeB, samarium cobalt is more suitable for working in high temperature environment (>200℃).
Application of permanent magnet
Permanent magnets are widely used in various fields such as electronics, electrical, machinery, transportation, medical and daily necessities. Such as the permanent magnet of the speaker and telephone receiver; the magnetic system of the magnetoelectric meter; the magnetic pole of the generator and the permanent magnet motor; the permanent magnet device used in the machine manufacturing industry (such as the permanent magnet chuck of the surface grinder, etc.), the magnetic suspension system, and the magnetic bearing ; Magnetic separation system, magnetic separation, magnetic purification water system, magnetron, magnetic system of proton accelerator, etc.
China Permanent Magnet Manufacturer www.ymagnet.com supplies permanent magnetic tools (Applied magnets) for scientific experiments or for industrial applications, in kinds of materials such as NdFeB/NIB/neodymium iron boron, etc.
This product is not a toy and is not to be used by children. This product is to be used for scientific experiments or for industrial applications. This product contains strong Neodymium magnet(s) that can be harmful or fatal if swallowed. Strong Neodymium magnets are fragile, they are brittle and will break or chip if they hit a hard surface or are snagged together. Always use the utmost care when handling Neodymium magnets.