What is rare earth permanent magnetic powder

What is rare earth permanent magnetic powder?

Rare earth permanent magnet powder is a common form of material existence. It is a powder aggregation composed of rare earth permanent magnet particles of a certain size. The quantitative change of the size, morphological structure and surface state of rare earth permanent magnet particles can lead to the qualitative change of macro characteristics of rare earth permanent magnet powder.
The development of rare earth permanent magnet powder engineering has blended with other disciplines, forming ultra-fine grinding, precision classification, high homogenization, dispersion, composite coating, modification and modification, drying, sintering and molding, storage, packaging, transportation, synthesis and application of nano-rare earth permanent magnet powder, performance test of rare earth permanent magnet powder and other operating units, synthesis process or integration technology.
The surface modification of rare earth permanent magnet powder refers to the surface treatment of the particles composed of rare earth permanent magnet powder by physical or chemical methods. According to the needs of application, the physical and chemical properties of the surface are changed purposefully, the process of surface morphology and structure. Surface modification is also called surface modification or surface modification.
Surface modification technology of rare earth permanent magnet powder materials is an important method to regulate material properties, expand application fields and improve use value.

Main characteristics of rare earth permanent magnet powder

Granularity:

• Particle size: usually expressed in diameter. Equivalent radius for irregular particles;
• Particle size distribution: the percentages of particles with different sizes; Particle shape particle shape represents the geometric shape of rare earth permanent magnet powder particles. The commonly used particle shapes include spherical shape, slice shape, needle shape, cylindrical shape, etc.

Flowability:

Flowability refers to the flowability of rare earth permanent magnet powder.

Filling Characteristics:

Filling characteristics are the basis of rare earth permanent magnet powder forming. Due to irregular shape and rough surface of rare earth permanent magnet powder, there are a large number of gaps between accumulated rare earth permanent magnet powder particles.

Factors affecting fluidity of rare earth permanent magnet powder

Due to the lag characteristic of the interaction force between particles, the accumulation states of rare earth permanent magnet powder are various. The research on the fluidity and stacking behavior of rare earth permanent magnet powder is the basis of rare earth permanent magnet powder engineering. It is a link between the properties of rare earth permanent magnet powder and many unit operations related to rare earth permanent magnet powder technology, for example, rare earth permanent magnet powder storage, feeding, transportation, mixing, etc.
The reason why rare earth permanent magnet powder flows is its essence is the imbalance of particle force in rare earth permanent magnet powder. The analysis of particle force shows that the particle force has gravity, adhesion force between particles, friction force, electrostatic force, etc., has the greatest impact on the flow of rare earth permanent magnet powder is gravity and adhesion between particles.
Specific to relevant parameters, it includes particle type, average particle size, particle size distribution, wet content, particle shape, specific surface area, density, storage time and particle interaction, etc.

Present Situation of rare earth permanent magnet powder

Rare earth permanent magnet is the industry with the largest output value and strategic position in rare earth industry. The manufacture and molding process of rare earth permanent magnet powder is the weakest link in domestic NdFeB industry, which has a great gap with foreign countries.
The research on the manufacturing process of rare earth permanent magnet powder is relatively backward. Due to the difference in fluidity of rare earth permanent magnet powder, isostatic pressing process is still needed in the manufacturing process of domestic magnets, and primary molding technology has not been solved;
In the process of sintering, the shrinkage ratio of magnet is different with the performance change of rare earth permanent magnet powder. In the manufacturing process of magnet products, the increase causes a large amount of post-processing and reduces the yield of rare earth materials.
Rare earth permanent magnet powder and molding process and rare earth permanent magnet powder standardization restrict the development of intelligent manufacturing in domestic NdFeB enterprises, and are also the key points of innovation and technological progress in NdFeB industry.

Development Trend of rare earth permanent magnet

Rare earth permanent magnet powder material is an essential intermediate basic material in the preparation process of functional materials. Rare earth permanent magnet powder materials include ultrafine grinding, precision classification, high homogenization, dispersion, composite coating, modified quality improvement, technical units such as performance detection evaluation, storage, packaging and transportation of drying and rare earth permanent magnet powder materials, apply the common key technologies of each unit of rare earth permanent magnet powder material to the Rare earth permanent magnet Industry, it can optimize the particle size distribution of the magnetic material rare earth permanent magnet powder, improve the fluidity of the rare earth permanent magnet powder, and then reduce or optimize the preparation link of neodymium iron boron material, and improve the performance, quality and consistency of the magnetic material.
At present, a lot of research work has been carried out in nano rare earth materials and rare earth permanent magnet superfine alloy powder at home and abroad, especially in the Rare earth permanent magnet Industry, ultra-fine permanent magnet rare earth permanent magnet powder has become the main innovation point for reducing heavy rare earth and comprehensive utilization of high abundance rare earth.
Rare earth ultrafine powder is not only a new material, but also a raw material for preparing new materials. It has excellent comprehensive characteristics of new materials and great application prospect.
Nd-Fe-B raw material alloy as the precursor of magnetic powder preparation, its grain size and morphology will affect the refinement of subsequent magnetic powder. The traditional research focuses on fast-setting alloy as the initial alloy, in order to further refine the crystalline of the sintered magnet, Sagawa Zhen and his research team used the helium jet mill technology developed in the early stage, single item magnetic powder particles with average diameter of 500nm or even smaller were obtained by using Hydrogenation-differentiation-dehydrogenase-recombination (HDDR) magnetic powder of submicron structure as initial alloy. Br=l3.39kGs,Hcj20.98k0c,(BH)max = 43.62MGOe sintered magnet without heavy rare earth and high coercive force was successfully obtained.
In the research work of reducing the grain size, a new nano-form has also been produced, Namely Exchange-coupled nano-composite permanent magnet materials, including hard magnetic phase and soft magnetic phase. Professor Liu Ping of the Chinese Academy of Sciences has made a number of important research achievements in his more than 20 years of research on Magnetism and Magnetic Materials, and has first adopted the “bottom- up process to synthesize nanocrystalline composite permanent magnet materials in the world; the influence of soft magnetic phase and interface on magnetic · exchange coupling is clarified, and the concept of gradient interface nano-composite material is put forward. The technology of preparing nano-particles by salt bath annealing and active agent assisted high energy ball milling technology is invented, it has received extensive attention from international peers.
Among Toyota’s new magnet, Toyota chooses to use cheaper lanthanum and cerium instead of neodymium and dysprosium. Of course, the main producing areas of lanthanum and cerium, which are also rare earth elements, are also China, so this does not solve the problem of the domination of the upstream supply chain. In order to reduce the content of neodymium, Toyota has taken a variety of measures. It is not realistic to simply replace the neodymium in the magnet with lanthanum and cerium, because this will produce a piece of inferior magnet with low resistance to resistance to heat and heat, which means that the performance of the motor will not be guaranteed. Therefore, Toyota’s new magnet fixes all lanthanum and cerium particles in its core, and then uses a layer of neodymium to wrap the core. In addition, Toyota has reduced the size of all metal particles. According to research, reducing the size of the rare earth magnet component can effectively improve the magnetic energy stored by the magnet. However, this is enough to reduce the cost of the permanent magnet motor.
Source: Network Arrangement – China Permanent Magnet Manufacturer – www.rizinia.com