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Demagnetization of NdFeB at high temperature and its effective solution

Publish Time: 2024-08-22
Neodymium iron boron, also known as NdFeB magnet, is a tetragonal crystal formed by neodymium, iron and boron (Nd2Fe14B). Neodymium magnets were discovered by Masato Sagawa of Sumitomo Special Metals in Japan in 1982. The magnetic energy product (BHmax) of this magnet is greater than that of samarium cobalt magnets, and it was the material with the largest magnetic energy product in the world at that time. Later, Sumitomo Special Metals successfully developed the powder metallurgy process. General Motors successfully developed the melt-spinning process, which can produce NdFeB magnets. This magnet is the strongest permanent magnet and the most commonly used rare earth magnet today.

NdFeB can last for a long time at room temperature, but it is well known that it will demagnetize at high temperatures. The combination of cost and performance of NdFeB magnets makes them a popular choice for the use of traditional magnets and the creation of new product applications. In the case of a sharp increase in existing strength, a smaller magnet is allowed to be used, which is beneficial to most designs.


The processing procedures of NdFeB magnets at high temperatures need to be careful, because NdFeB magnets are easy to demagnetize at high temperatures. Below we will understand with you the problem of high-temperature demagnetization of NdFeB magnets. Due to the high content of neodymium iron in NdFeB magnets, they are also easy to oxidize, so the various coatings that meet these conditions depend on the operating environment of NdFeB magnets.

The reason why NdFeB demagnetizes in a high-temperature environment is determined by its own physical structure. The reason why general magnets can generate magnetic fields is that the electrons carried by the material itself rotate around the atoms in a certain direction, thereby generating magnetic field forces, which in turn affect related matters around them. However, the rotation of electrons around atoms in a given direction is also limited by temperature conditions. Different magnetic materials can withstand different temperatures. Under excessively high temperatures, electrons will deviate from their original orbits, causing chaos. At this time, the local magnetic field of the magnetic material will be disrupted, resulting in demagnetization.

The temperature resistance of strong NdFeB magnets is about 200 degrees. If it exceeds 200 degrees, demagnetization will occur. If the temperature is higher, the demagnetization phenomenon will be more serious.


Several effective solutions for high-temperature demagnetization of NdFeB magnets

‌1. Avoid exposing NdFeB magnets to excessively high temperatures, pay special attention to their critical temperature, which is 200 degrees, and adjust the working environment temperature in time to minimize the occurrence of demagnetization.

‌2. Improve the performance of products using NdFeB magnets, so that they have a more temperature-friendly structure and are not easily affected by the environment.

‌3. Choose the same energy product material with high coercivity. If the above methods still cannot solve the problem, consider choosing a material with lower energy product but higher coercivity, or in extreme cases, consider using samarium cobalt materials.

These methods are designed to reduce or avoid the demagnetization problem of NdFeB magnets in high temperature environments by adjusting the use environment, improving product performance, or replacing materials.

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