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NdFeb Magnets Preparation Process
Aug 23, 2017

NdFeb Magnets Preparation Process

NdFeB magnets milling principle:

    Magnetic powder is the abbreviation of magnetic powder, is a large number of NdFeB base material particles and particles between the gap formed by the assembly. The powder body is a substance between the solid and the colloid. In the 0.1um below the solid material called colloid, the size of lmm above known as dense body or solid.

    NdFeB magnet powder There are many small pores between the particles and the connection surface is very small, the surface of the atoms can not form a strong bond force, so the powder body does not like the compact body as a fixed shape, and showed similar to the liquid fluidity. Dense body without macroscopic pores, by the bond strength of the atom.

    Preparation of rare earth magnet alloy powder metallurgy method commonly used. Use this method to produce alloy ingots. NdFeB magnets powder powder is divided into coarse, medium and fine three kinds of processes, milling requirements of the particle size of 3 ~ 5um. Rare earth magnet metal oxidation, such as the formation of Smz 03, Nd2 03, etc., these oxide powder in the high temperature air will spontaneous combustion, magnetic interaction, the powder becomes secondary powder particles, that is, a few powder particles in the powder Between the van der Waals force, the London force, and the magnetic interaction forces, so that the above-mentioned powder in the rare earth permanent magnet alloy is poor in fluidity and causes some difficulties in the forming process in the next process.

NdFeB Magnet Powder Particles Requirement:

    The average particle size of the NdFeB magnets is measured by the average particle size analyzer. The size of the magnetic powder particles is 3 ~ 5um. The magnetic particle size distribution is measured by the particle size distribution instrument. The size of the powder particles is 3 ~ 5um 80% 1um powder, less than 15% in production. More than 5um to be as small as possible, the powder particle size frequency distribution is normal distribution or Gaussian part.

    On the oxygen content requirements, early granulation in the vacuum degree of 10 - 2Pa, with nitrogen protection. When the powder is pulverized by the airflow pulverizer, the amount of airflow is less than 50 ppm.

    On the shape of the magnetic powder, the powder particles are spherical or nearly spherical, the powder particles of the crystal particles to be as little as possible. To achieve the above requirements of the magnetic particles is the most basic requirements of sintered NdFeB.

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