Brief introduction of NdFeB most powerful neodymium magnet.
NdFeB is the most powerful neodymium magnet in all magnetic materials on the market. The most powerful Nd-Fe-B magnet is prepared by powder sintering. Because NdFeB is the most powerful neodymium magnet with super strong magnetic force, it is widely used in light and short products.
Generally speaking, in order to prevent surface oxidation, the surface of the most powerful NdFeB magnet is usually treated with nickel plating, zinc plating or epoxy resin. However, even if the surface is treated with anti-corrosion treatment, surface oxidation will still occur after a period of time (depending on the storage environment, about one year).
Although there is oxidation on the surface, it has no effect on the magnetic strength and properties of the magnet. In addition, attention should be paid to the temperature coefficient of the material grade. Although the magnetic force of NdFeB magnet is super strong, its temperature coefficient is lower than that of alnico alloy magnet.
Firstly, the common sintered NdFeB grades can be divided into seven categories: n, m, h, SH, uh, eh and th. Except for category n, every other type will appear at the end of the product brand. For example, n38m is M series and n38th is th series. If there is no letter after “N38″, then it is n series. (of course, there are some uncommon brands with higher performance. If you are interested, you can understand them by yourself. Today we will only introduce the more common brands.)
Secondly, there are four indicators to measure the performance of sintered NdFeB products.
Br remanence: Tesla (T) and Gauss (GS), 1gs = 0.0001t. It refers to the magnetic induction intensity of sintered NdFeB magnets when a magnet is magnetized by an external magnetic field in a closed-circuit environment until the technology is saturated and the external magnetic field is withdrawn. Generally speaking, it can be understood as the magnetic force of the magnetized magnet.
HCB coercivity: the unit is oer or a / m, 1A / M = (4 π / 1000) OE, 1 OE = (1000 / 4 π) a / m. When the magnet is magnetized reversely, the value of the reverse magnetic field strength required to reduce the magnetic induction to zero is called the magnetic induction coercivity. But at this time, the magnetization of the magnet is not zero, but the reverse magnetic field counteracts the magnetization of the magnet. At this time, if the external magnetic field is removed, the magnet still has certain magnetic properties.
Hcj intrinsic coercivity: the intensity of the reverse magnetic field required to reduce the magnetization of the magnet to zero. We call it intrinsic coercivity. Its unit of measurement is the same as coercivity. The classification of magnetic materials is based on their intrinsic coercivity. Low coercivity n, medium coercivity m, high coercivity h, very high coercivity uh, very high coercivity eh, and very high coercivity th. The intrinsic coercivity of Nd-Fe-B magnets will decrease with the increase of temperature. Therefore, when choosing to use Nd-Fe-B magnets, we must choose the brand suitable for our use. We will make a further introduction in the next issue
(BH) max maximum magnetic energy product: represents the magnetic energy density established by the space between the two magnetic poles of the magnet, that is, the magnetostatic energy per unit volume of the air gap. It is the maximum value of the product of Br and Hcj, and its size directly indicates the performance of the magnet. The number in the brand of magnetic material represents the theoretical maximum magnetic energy product of the product.
Post time: Jan-15-2021