Three environmental factors affect function of high temperature resistant magnet
Environment temperature. Since sintered NdFeB has a negative temperature coefficient (αBr<-0.13%/°C, αHcj<-0.6%/°C), the instantaneous maximum temperature and the continued maximum temperature of the operating environment will cause different degrees of demagnetization of the magnet itself. Contains reversible and irreversible, rehabilitative and non-recoverable.
Environment humidity. NdFeB itself is easily corroded and oxidized. Generally, we use external treatment to maintain permanent magnets, but we cannot fundamentally deal with the influence of ambient humidity on magnets. The boring environment, the longer the service life of the magnet. How to measure the bump of magnetic function?
There are three main parameters: Residual Induction, unit Gauss, which is a parameter to measure the strength of the magnetic field supplied by the magnet; Coercive Force, unit Oersteds, is a parameter to measure the anti-demagnetization ability; the magnetic energy product BHmax , the unit Gauss-Oersteds, is a physical quantity that characterizes how much energy can be stored.
The permanent magnet high temperature resistant magnets are divided into two categories: the top categories are: metal alloy high temperature resistant magnets containing NdFeB high temperature resistant magnet Nd2Fe14B), samarium cobalt high temperature resistant magnets (SmCo), AlNiCo high temperature resistant magnets (ALNiCO) second The main categories are: ferrite permanent magnet data (Ferrite) high temperature magnets have a special internal structure of the atom, and they have a magnetic moment. Shape OF High temperature resistant magnets: square magnets, tile shaped magnets, block magnets, cylindrical magnets, ring magnets, disc magnets, magnetic bar, Magnetic tube, Characteristic of high temperature resistant magnet: samarium cobalt magnet, neodymium iron boron magnet, ferrite magnet, AlNiCo magnet, iron chrome cobalt magnet, professional high temperature resistant magnet : Magnetic components, motor high temperature magnets, rubber magnets, strong high temperature magnets, plastic magnets, etc. High temperature resistant magnets are divided into permanent high temperature magnets and soft magnetic. Permanent high temperature resistant magnets are coupled with strong magnetism, so that the spin of the magnetic material and the angular momentum of the electron are arranged in a fixed direction, and the soft magnetic is added with current (also a plus) Magnetic method) When the current is removed, the soft iron will gradually lose its magnetism.
High-temperature magnets of different nature have different composition characteristics, and the size of the magnetic force is not the same. The usual high temperature resistant magnets can be distinguished by the following four types:
1. NdFeB high temperature resistant magnet: It is the high temperature resistant magnet with the highest commercialization function. It is called magnetic king and has a very high magnetic function. Its maximum magnetic energy product (BHmax) is higher than ferrite (Ferrite). More than double. Its own machining function is also quite good. Operating temperatures up to 200 degrees Celsius. And its texture is hard, the function is stable, and it has good cost performance, but because of its strong chemical activity, it is necessary to treat its exterior coating. (such as Zn, Ni, electrophoresis, passivation, etc.).
2. Ferrite high temperature resistant magnet: Its main raw material contains BaFe12O19 and SrFe12O19. Made by ceramic technology, the texture is hard and brittle. Because the ferrite high temperature resistant magnet has excellent temperature resistance, low price and moderate function, it has become the most widely used permanent magnet.
3. AlNiCo high temperature resistant magnet: It is an alloy composed of aluminum, nickel, cobalt, iron and other trace metal elements. Forging technology can produce different scales and shapes, and the processability is excellent. Forged AlNiCo permanent magnets have the lowest reversible temperature coefficient and can operate at temperatures above 600 degrees Celsius. AlNiCo permanent magnet products are widely used in various instruments and other fields of use.
4. SmCo is classified into SmCo5 and Sm2Co17 depending on the composition. Because of the high price of the data, its development is limited. Samarium Cobalt (SmCo), as a rare earth permanent high temperature magnet, not only has a high magnetic energy product (14-28 MGOe), firm coercivity and outstanding temperature characteristics. Compared with NdFeB high temperature resistant magnets, samarium cobalt high temperature resistant magnets are more suitable for operation in high temperature environments. The midpoint of the strip-shaped high temperature resistant magnet is suspended by a thin wire. When it stops, its two ends point to the south and north of the earth. The end pointing to the north is called the north pole or the N pole, and the end pointing to the south or S pole.