Modification method of neodymium magnet: Key strategy to improve performance

In today's era of rapid development of science and technology, high-performance magnetic materials play a vital role in many fields. Among them, NdFeB magnets are favored because of their excellent magnetic energy product, high coercivity and good mechanical properties. However, with the continuous improvement of application requirements, the performance of neodymium magnets has been put forward higher requirements. Therefore, how to improve the performance of neodymium magnet by modifying method has become the focus of current research. The modification methods of neodymium magnets and their effects on their properties will be discussed in detail.

1. The basic characteristics and application fields of neodymium magnets

Neodymium magnet, also known as NdFeb magnet, is an alloy permanent magnet material composed of neodymium, iron, boron and other elements. It has a very high magnetic energy product and coercivity, is currently known as one of the strongest permanent magnet materials. Due to its excellent magnetic properties, neodymium magnets are widely used in wind power generation, electric vehicles, electronic products, medical equipment and other fields. However, with the rapid development of these fields, higher requirements have been put forward for the performance of neodymium magnets, such as higher operating temperature, stronger corrosion resistance and better mechanical properties.

2. The modification method of neodymium magnet

Element doping modification
Element doping is an effective method to improve the performance of neodymium magnets. By adding other rare earth elements or non-rare earth elements to the neodymium magnet, its crystal structure and electronic structure can be changed, thus affecting its magnetic properties. Commonly used doping elements include dysprosium (Dy), terbium (Tb), cobalt (Co) and so on. For example, dysprosium element can replace part of neodymium element to form (Nd, Dy) 2Fe14B phase to improve the coercivity of the magnet; The cobalt element can replace part of the iron element to form the (Nd, Co) 2Fe14B phase, which improves the Curie temperature and corrosion resistance of the magnet.
Nanocomposite modification
Nano-composite modification is to prepare a composite material with excellent properties by combining nano-particles with neodymium magnet matrix. Nanoparticles have unique surface effects and small size effects, which can significantly improve the magnetic properties and mechanical properties of neodymium magnets. Commonly used nanoparticles include oxides, carbides, nitrides, etc. For example, the coercive force and corrosion resistance of the magnet can be improved by combining nano-sized magnesium oxide particles with neodymium magnet matrix. The hardness and wear resistance of the magnet can be improved by composite of nano-sic particles with neodymium magnet matrix.
Grain boundary diffusion modification
Grain boundary diffusion modification is to change the grain boundary structure and properties of neodymium magnets by introducing other elements or compounds at the grain boundary, so as to improve the performance of magnets. This method can effectively reduce the defect density at the grain boundary and reduce the adverse effect of the grain boundary on the magnetic properties. Common grain boundary diffusion elements include rare earth elements such as dysprosium and terbium and non-metallic elements such as oxygen and nitrogen. For example, introducing dysprosium into neodymium magnets through grain boundary diffusion can improve the coercivity of the magnets. The corrosion resistance of neodymium magnets can be improved by diffusing oxygen into them through the grain boundaries.
Heat treatment modification
Heat treatment is one of the important means to improve the properties of neodymium magnets. By controlling the heat treatment process parameters (such as temperature, time, atmosphere, etc.), the crystal structure and phase composition of neodymium magnets can be adjusted, thus affecting their magnetic properties. Commonly used heat treatment methods include tempering treatment, aging treatment, annealing treatment and so on. For example, the residual stress in neodymium magnets can be eliminated by tempering treatment to improve their magnetic properties. By aging treatment, the second phase in neodymium magnet can be precipitated and grow, and its coercive force can be improved. The crystal orientation and phase composition of neodymium magnets can be adjusted by annealing treatment to optimize their magnetic properties.
Surface modification
Surface modification is a method to improve the performance of neodymium magnets by changing their surface properties. Common surface modification methods include coating, coating, chemical vapor deposition, etc. For example, coating a neodymium magnet with an antioxidant coating can effectively prevent its oxidation corrosion; The electrical and thermal conductivity of neodymium magnet can be improved by plating a metal film on its surface. The wear resistance and corrosion resistance of neodymium magnets can be improved by deposition of a hard film on the surface by chemical vapor deposition.

3. Practice cases of modification methods of neodymium magnets

Taking a high performance neodymium magnet manufacturer as an example, the company adopted a combination of modification methods to meet the performance requirements of neodymium magnets. Firstly, proper amount of dysprosium and cobalt is added to neodymium magnet through element doping modification, which increases the coercivity and Curie temperature of the magnet. Secondly, nano-sized magnesium oxide particles were combined with neodymium magnet matrix by nano-composite modification to improve the corrosion resistance of the magnet. Thirdly, dysprosium element is introduced into neodymium magnet grain boundaries by grain boundary diffusion modification, which further reduces the grain boundary defect density. Finally, the crystal orientation and phase composition of neodymium magnet were modified by heat treatment to optimize its magnetic properties. After this series of modification measures, the company's neodymium magnet products have been significantly improved in performance to meet the needs of high-end applications.

4. Summary and prospect

Through the discussion of modification methods of neodymium magnets, it can be seen that element doping, nanocomposite, grain boundary diffusion, heat treatment and surface modification are effective ways to improve the performance of neodymium magnets. In the future, with the continuous development and innovation of science and technology and the increasing demand for high-performance magnetic materials, I believe that the modification technology of neodymium magnets will be more widely used and developed to promote the upgrading and development of China's magnetic materials industry to make greater contributions. At the same time, we also look forward to discovering more new modification methods and materials in the future to open up new ways to improve the performance of neodymium magnets.

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