Permanent magnet materials are widely used in various motors in automobiles, home appliances, energy, machinery, medical, aerospace and other industries, as well as components that need to generate strong gap magnetic fields. Magnetic materials are closely related to all aspects of informatization, automation, mechatronics, national defense, and national economy, and have irreplaceable advantages in many fields. Magnetic materials are generally Fe, Co, Ni elements and their alloys, rare earth elements and their alloys, and some Mn compounds. Magnetic materials are divided into soft magnetic materials and hard magnetic materials according to the degree of difficulty of magnetization. Compared with permanent magnetic materials, soft magnetic materials are relatively easy to magnetize and demagnetize. Their main functions are magnetic conduction, electromagnetic Energy conversion and transmission; hard magnetic materials are also called permanent magnetic materials. After being magnetized by an external magnetic field, even under the action of a considerable reverse magnetic field, they can still maintain part or most of the original magnetization direction, and have electrical signal conversion. , Electric energy-mechanical energy conversion function, is widely used in various motors in automobiles, home appliances, energy, machinery, medical, aerospace and other industries, as well as components that need to generate strong gap magnetic fields.

NdFeB magnets are the third generation of rare earth permanent magnets and are the most widely used. Permanent magnet materials can be divided into three categories: rare earth permanent magnets, ferrite permanent magnets and other permanent magnets. Among them, rare earth permanent magnet materials have continued to develop rapidly since the 1960s, and can be divided into four generations according to the chronological order of their development and application: the first generation is RECo5 series materials represented by SmCo5; the second generation is RECo17 series materials represented by Sm2Co17 Magnet; the third generation is the neodymium-iron-boron (NdFeB) magnetic material successfully developed in the early 1980s. Because it is an Fe-based rare earth material, it has the characteristics of lower price and excellent performance. It quickly replaced RECo17 in many fields. Type magnets are currently the most widely used rare earth permanent magnet materials, while the fourth generation is iron-nitrogen (Re-Fe-N) and iron-carbon (Re-Fe-C) systems, which are still in the stage of experimental development, and may require dozens of It will take a relatively long time of years to realize large-scale production and application.

NdFeB magnets are well-deserved "Magnetic King". NdFeB has excellent performance in "magnetic performance" coefficients such as intrinsic coercive force, magnetic energy product and remanence: 1. It has strong anti-demagnetization ability, and the maximum intrinsic coercive force can reach that of samarium cobalt permanent magnet. About 2 times that of ferrite, about 3-10 times that of ferrite; 2. Instruments and meters applied with NdFeB magnetic materials have more potential in the field of lightweight, the maximum magnetic energy product is 1.5 times that of samarium cobalt permanent magnets, 10 times that of ferrite 3. The ability to resist the external magnetic field is the strongest, the maximum residual magnetism is 1.2 times that of samarium cobalt permanent magnet, and 3-4 times that of ferrite. Therefore, the comparative advantages of NdFeB magnets in intrinsic coercive force, magnetic energy product and residual magnetism are widely used, and they are well-deserved "magnet kings". In contrast, the only advantage of ferrite is that the production cost is lower, so it is mostly used in relatively low-end fields. Due to the high performance requirements in high-end fields, ferrite is hardly used; samarium cobalt permanent Although magnetism can work in a wide temperature range, its mechanical properties are not good, and it contains cobalt, so the cost performance is not high. Therefore, it is often only used in military, aerospace and other fields that require high temperature performance.

1.2 High-performance NdFeB magnets--difficult to replace, with both rigid requirements and rapid growth properties

Sintered NdFeB magnets are the mainstream type. According to different production processes, NdFeB magnets can be divided into three types: sintering, bonding and hot pressing. 1. Sintered NdFeB magnetic material is made by powder metallurgy process, the prefabricated material is made into fine powder, pressed into billet, and then sintered. It has the characteristics of high magnetic energy product, high coercive force and high working temperature. Mainly used in motors, generators and other fields; 2. Bonded NdFeB magnetic material is a magnet made by uniformly mixing NdFeB magnetic powder with polymer materials and various additives, and then using molding methods such as molding or injection molding. The performance of bonded NdFeB is not as good as that of sintered NdFeB, but it has the advantages of simple process, low cost, small size, high precision, uniform and stable magnetic field, etc. It is mainly used in information technology, office automation, consumer electronics and other fields; 3. Hot-pressed NdFeB permanent magnet material is a magnet with high magnetic properties made by hot extrusion and hot deformation process. It has high density, high degree of orientation, good corrosion resistance, high coercive force and near net shape At present, only a few companies have mastered the production process, the patent barriers and production costs are high, and the total output is small. Therefore, sintering, bonding, and hot-pressed NdFeB have their own characteristics in terms of performance and application, and the overlapping range of downstream application fields is relatively small, and the relationship between them is not substitution and occupation, but more complementary. Due to the advantages of sintered NdFeB in performance and cost, it is currently the rare earth permanent magnet material with the highest output and the most widely used, and it is the mainstream type in the market.

NdFeB magnetic materials with different performance levels are used in different application fields. Emerging fields often have higher performance requirements, and high-end NdFeB magnetic materials are difficult to be replaced. Sintered NdFeB magnetic materials are divided into low coercive force (N), medium coercive force (M), high coercive force (H), super high coercive force (SH), super high Coercive force (UH), extremely high coercive force (EH), and high coercive force (TH) seven categories. According to industry practice, the sum of intrinsic coercive force (Hcj, kOe) and maximum magnetic energy product ((BH)max, MGOe) is greater than 60 sintered NdFeB permanent magnet materials, which belong to high-performance NdFeB permanent magnet materials. Various types of motors, compressors, and sensors are mainly used in the field of high-tech barriers, and are divided according to the downstream applications of the products, including traditional automotive EPS, new energy automotive motors, wind power, frequency conversion appliances, energy-saving motors and other emerging fields, especially Yes, with the development of new energy vehicles in recent years, the demand for magnetic materials for new energy vehicle motors has also become the main growth point for the demand for high-end NdFeB magnetic materials. From the perspective of industry trends: 1. In the low-end field, samarium-cobalt magnets, ferrites, and low-end NdFeB magnetic materials have a high probability of direct "hand-to-hand combat" and full competition. In this application field, the price/performance ratio is Priority considerations; 2. In the high-end field, due to the incomparable high performance of high-end NdFeB, which matches the high-performance requirements of emerging fields, the demand for high-performance NdFeB magnetic materials is difficult to be replaced, and downstream emerging fields are rapidly driving demand. Therefore, the application trend of high-performance NdFeB can be summed up by two key words—demand rigidity and rapid growth.