The raw material composition and production process of neodymium iron boron magnetic steel determine its inherent magnetic properties, and after becoming a strong magnetic product, its working environment (including temperature, humidity, and other factors) will affect the performance of its inherent magnetic properties. Improper use can result in permanent demagnetization.
| 矫顽力等级 | 最高工作温度 | ||
| N | Normal | 低矫顽力 | 80°C |
| M | Medium | 中等矫顽力 | 100°C |
| H | Highe | 高矫顽力 | 120°C |
| SH | Super High | 特高矫顽力 | 150°C |
| UH | Ultra High | 超高矫顽力 | 180’C |
| EH | Extremely High | 极高矫顽力 | 200°C |
| AH | Aggressively High | 致高矫顽力 | 230°C |
- The influence of raw material composition on the strong magnetic properties of neodymium iron boron
As the name suggests, neodymium iron boron is a magnetic material made by powder metallurgy of rare earth metals neodymium, pure iron, and boron. In order to further enhance the magnetic properties of neodymium iron boron, other elements can be added on the basis of the ternary Nd-Fe-B material. However, the effect of element addition on the magnetic properties may be bidirectional, and the specific requirements for the magnetic material properties of neodymium iron boron should be determined according to the application scenarios of strong magnetism.
2.The influence of production process on the strong magnetic properties of neodymium iron boron
In order to obtain high-performance neodymium iron boron permanent magnets, new technologies and processes are constantly emerging. In the production process of sintered NdFeB, the main problem is to prevent the precipitation of α – Fe phase and the oxidation of the alloy, which makes it difficult to obtain the ideal microstructure. To solve these problems, new methods and processes continue to emerge in practice, such as adding anti oxidants, lubricants, and using rapid quenching strip spinning method to prepare magnets, dual phase method preparation process, wet pressing forming process, etc
The biggest advantage of adding an antioxidant is that it reduces the oxygen content of the final magnet, and the magnetic powder can be ground finer, which is beneficial for improving the coercivity. In addition, due to the decrease in oxygen content, it is also beneficial for improving the coercivity. Compared with traditional processes, the intrinsic coercivity of magnets with added anti-oxidation agents can be increased by about 160kA/m.
Adding lubricant reduces the friction between magnetic particles, improves their flowability, enhances their orientation, and thus increases residual magnetism.
The thickness of neodymium iron boron ribbon prepared by strip spinning method is 0.25-0.35mm, which can completely eliminate the α – Fe phase. Due to the enhanced antioxidant capacity of the powder produced by the strip spinning method, the grain size of the magnet decreases and the coercivity is significantly improved.
3. The influence of working environment on the strong magnetic properties of neodymium iron boron
Temperature: Neodymium iron boron magnets have strict operating temperature limits. When the operating temperature is higher than the operating temperature, the magnet may experience demagnetization, while when it is higher than the Curie temperature, the demagnetization of the magnet will be irreversible.
Humidity: Sintered neodymium iron boron is a magnetic material formed by powder metallurgy process, and its internal structure has voids, which are very easy to oxidize. Therefore, sintered neodymium iron boron will be coated for anti-corrosion treatment. But the magnetic layer cannot fundamentally solve the impact of environmental humidity on magnets. The drier the environment, the more long-lasting the magnetic energy of the magnet.