China permanent magnet manufacturer:

Demagnetization of NdFeB at high temperature and its effective solution

Nd-Fe-B, the “crown of rare earth”, is a unique rare material. Because of its powerful magnetic carrying function, it will become the favorite of the industrial revolution in the 21st century. The revolution of motor industry caused by it has become a high concern of motor experts and automobile experts all over the world. According to the prediction of experts in the industry, the motor in the 21st century will be the world of NdFeB magnets. Neodymium iron boron magnet is recognized as a high-performance and cost-effective magnet product in the magnetic material industry. Many high-tech fields are designated to use it to make all kinds of spare parts, such as national defense and military, electronic technology, medical equipment, electrical machinery and other fields. The more we use, the easier it is to find problems. Among them, the demagnetization phenomenon of NdFeB magnets in high temperature environment has attracted much attention.

Why does NdFeB demagnetize at high temperature?

The reason why NdFeB demagnetizes at high temperature is determined by its physical structure. The reason why a general magnet can produce a magnetic field is that the electrons carried by the material itself rotate around the atom in a certain direction, thus producing a certain magnetic force, which affects the surrounding affairs. But the electron revolves around the atom according to the given direction is also limited by certain temperature conditions. Different magnetic materials can withstand different temperatures. In the case of too high temperature, the electron will deviate from the original orbit, causing chaos. At this time, the local magnetic field of the magnetic material will be disturbed, resulting in demagnetization.
The temperature resistance of NdFeB magnet is about two hundred, that is, if the temperature exceeds two hundred, demagnetization will occur. If the temperature is higher, demagnetization will be more serious
The most effective solutions for high temperature demagnetization of NdFeB magnets are as follows

  • 1. Don’t put NdFeB magnet products in too high temperature, especially pay attention to its critical temperature, that is, two hundred degrees. Adjusting its working environment temperature timely can reduce demagnetization as much as possible.
  • 2Starting from technology, improve the performance of products using NdFeB magnets, so that it can have a more temperature structure, not easily affected by the environment.
  • 3You can also choose high coercivity materials with the same magnetic energy product. If not, you have to sacrifice a little magnetic energy product and find a higher coercivity material with lower magnetic energy product. If not, you can choose samarium cobalt. As for reversible demagnetization, you have to choose samarium cobalt.

PS: each material has different characteristics, so it is economical to choose the right one. When designing, we should consider it carefully, otherwise it will bring loss!
How to reduce or prevent the thermal demagnetization oxidation of NdFeB, which leads to the decrease of coercivity?
A: This is the problem of thermal demagnetization, which is really difficult to control. Pay attention to the control of temperature, time and vacuum during demagnetization.
How much frequency does the NdFeB magnet vibrate to demagnetize?
A: Permanent magnet magnetism will not be demagnetized because of frequency vibration. High speed motor will not demagnetize even when the speed reaches 60000 rpm.
Source: China Permanent Magnet Manufacturer



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