High-performance HDDR anisotropic NdFeB magnetic powder advantage

- Nov 16, 2017 -

1, high performance HDDR anisotropic bonded NdFeB magnetic powder has a wide range of applications, due to its magnetic properties far higher than the traditional materials such as ferrite, and MQ nearly double the traditional magnetic powder. This plays a key role in the miniaturization, weight reduction, precision and high performance of electromagnetic products, so the product has a vast international market.

2, Since R2Fe14B and R2Fe17 in the magnetic powder grains are both ferromagnetic phases, the non-ferromagnetic R-rich boundary phase is not required as a necessary condition for obtaining a high coercive force, so that the phase composition of R2Fe14B and R-rich boundary R The magnet has a higher saturation magnetization and a magnetic energy product value

3. The magnetic powder produced by the invention adopts the hydrogen explosion effect through the hydrogenation-disproportionation-dehydrogenation-recombination process and has a large number of brecciated fracture zones in the particles, so the magnetic powder is easy to be crushed. Generally, the particle size of the magnetic powder is 100 μm.

4, the process consists of four stages. The first stage of hydrogen pressure of 0.2MPA, a temperature of about 200 degrees, is the main phase of NdFeB master alloy hydrogen absorption stage, forming a neodymium iron boron BH hydride. In the second stage, the hydrogen pressure is controlled at 0.25 MPA and the temperature is about 800 degrees. At this time, the NdFeB is disproportionated into three phases, and the hydrogen pressure at this stage plays a crucial role in the anisotropy of the NdFeB magnetic powder. The third stage of the temperature is maintained at 700 degrees, the hydrogen pressure is reduced to 1.0 ~ 5.0KPA range by vacuum, is the dehydrogenation stage, the pressure of this stage for the subsequent NdFeB magnetic anisotropy formation is also very important. The fourth stage, still maintain the temperature of 700 degrees, but the vacuum, so that 2ND and FEB three phase re-form NdFeB phase. NdFeB powder at this time has become anisotropic magnetic powder. Influence of hydrogen pressure on the magnetic properties of ternary NdFeB anisotropic magnetic powder in the second stage. It can be seen that with the increase of hydrogen pressure, the H of the magnetic powder gradually increases. When the hydrogen pressure reaches above 0.5 MPA, H reaches the saturation value and no longer increases. However, with the increase of the hydrogen pressure, B and BH first increase and then reach 0.03 MPA hydrogen pressure reached its maximum, indicating that NdFeB magnetic anisotropy has been formed. When the hydrogen pressure is further increased, both B and BH decrease, indicating that the hydrogen pressure in the disproportionation stage plays a key role in the formation of NdFeB magnetic powder anisotropy and that the hydrogen pressure range for obtaining the best magnetic properties is narrow. Precise control of the process parameters ensures that the C-axis direction of the grain in the magnetic powder is consistent with the C-axis direction of the mother alloy grains in the original powder. However, this parameter is very narrow. Now the company has mastered the production process parameters maturely and can produce high-performance Magnetic powder 30-40MGOe.

5, the choice of cheap praseodymium neodymium metal instead of pure neodymium metal permanent magnet material, the oxygen resistance and mechanical properties significantly improved, can be processed into various shapes of magnets. Widely used in various types of electronic devices and motors. In addition praseodymium neodymium price is about 80% of the price of neodymium, the proportion of neodymium in the ingredients at 25%, if calculated according to the current price of rare earth, the production of a ton of the magnetic powder, can reduce the cost of about 40,000 yuan, substantial economic benefits.

Article from NdFeB Industry Network

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