Grain Boundary Diffusion
Short Description:
● Mass production of high-performance NdFeB magnets with magnetic properties (BH) max+Hcj≥75, such as grades of G45EH, G48EH, G50UH, G52UH.
● Cost of GBD magnets is lower than that produced by conventional technology by more than 20%.
● Magnet Power team has developed both spraying and PVD processes. And we have mature technological processes and strict management systems.
● The GBD technology is suitable for NdFeB materials with a thickness of less than 10mm.
Grain boundary diffusion method, the specific process refers to the introduction of heavy rare earth elements Dy and Tb thin films on the surface of the magnet, the temperature of the rare earth rich phase is higher than the melting point of high temperature vacuum diffusion treatment, so that the heavy rare earth atoms along the grain boundary liquid phase to the interior of the magnet, the main phase grain epitaxis layer formed (Nd, Dy, Tb)2Fe14B shell structure; The main phase anisotropy field is enhanced. The grain boundary phase transformation is continuous and straight, the magnetic coupling effect of the main phase is suppressed, the Hcj of the magnet is significantly increased, and the Br and (BH)max of the magnet are not affected.
1. Reduce the amount of heavy rare earth: The same grade of magnets, the use of grain boundary diffusion can greatly reduce the use of dysprosium (Dy), terbium (Tb) and other heavy rare earth, thus reducing the cost. In the traditional process, a large number of heavy rare earths will enter the main phase grain, resulting in a significant reduction in remanence, but the grain boundary diffusion method makes the heavy rare earths mainly concentrated at the grain boundary, which can improve the coercivity while maintaining a high remanence.
2. Preparation of high comprehensive magnetic performance magnets: It can prepare high comprehensive magnetic performance magnets that cannot be reached by traditional technology, such as 50EH, 52UH, etc. By forming a heavy rare earth film on the magnetic steel surface and being heat treated in vacuum, the heavy rare earth enters into the magnet along the grain boundary, replacing the neodymium (Nd) atoms around the main phase grains to form a high coercive shell, which greatly improves the coercive force and has a very low remanence decline value.
3. Improve coercivity: It can significantly improve the coercivity of the magnet, and the coercivity increase is large, such as the use of Dy diffusion can improve 4kOe ~ 7kOe, the use of Tb diffusion can improve 8kOe ~ 11kOe, and the decrease of remanence is small (br decrease within 0.3kGs).
4. Repair surface magnetic properties: the damage of the magnet surface after machining will lead to the weakening of magnetic properties, especially for small-size samples, and the use of grain boundary diffusion technology can repair and enhance the magnetic properties of the magnet surface.
For good distribution of HRE at NdFeB grain boundaries. It is possible to develop high coceivity and not decrease Ms too much. G48EH,G52UH,G54SH grades, which are difficult developed by alloy technology, are produced by GBD technology. The quality of these magnets is determined by the structure of the magnets.Hangzhou magnet power can stably mass produce G45EH,G48EH,G50UH,G52UH and so on.
Magnet Power has obtained ISO9001 and IATF16949 certifications. The company has been recognized as a small-to-medium-sized technology firm and a national high-tech enterprise. As of now, Magnet Power has applied 20 patent applications，including 11 invention patents.
