Neodymium magnet

Neodymium magnet

Neodymium magnet, also known as NdFeB magnet, is a tetragonal crystal system formed by Neodymium, iron, and boron (Nd2Fe14B).In 1982, sumitomo’s special metal misaki sagawa discovered neodymium magnets.The magnetic energy product (BHmax) of this magnet was greater than that of samarium cobalt magnet, which was the largest magnetic energy product in the world at that time.Subsequently, sumitomo specialty metals successfully developed the powder metallurgy process, and general motors successfully developed the melt-spinning process to produce ndfeb magnets.The magnet is now the second most permanent magnet in magnetism after the absolute zero holmium magnet, and the most commonly used rare earth magnet.Ndfeb magnets are widely used in electronics such as hard drives, mobile phones, earphones and battery-powered tools.

In order to avoid the damage caused by corrosion, protective treatment should be done on the surface of permanent magnetic materials, such as electroplating with gold, nickel, zinc and tin, and surface spraying with epoxy resin.



Classification of editing

Ndfeb is divided into two kinds: sintered ndfeb and bonded ndfeb.And sintered ndfeb due to easy corrosion, surface coating, generally galvanized, nickel, environmental protection zinc, environmental protection nickel, nickel copper nickel, environmental protection nickel copper nickel.And sintered ndfeb is generally divided into axial magnetization and radial magnetization, according to the required working face to determine.

Surface treatment of ndfeb:

With a sintered ndfeb Japan, Germany, the European Union in the patent technologies such as the thawing, our country each big sintering factory of collaborative efforts, sintered ndfeb improve the product grade. As a high-tech applications for its comprehensive performance of the constantly improve, the requirements of the surface treatment of sintered ndfeb also greatly increased, the traditional processing method has been unable to meet the requirements of industrial progress. Electronic science and technology university, sichuan, jiaotong university, red rice and other scientific research institutions, from the microscopic molecular structure, essentially perfect surface treatment principle and industrial application technology development, after four years of Hard work and key technology

Breakthrough. Nanometer (3010) chelate thin film coating processing, the technology is original technology, nano membrane layer contains the active group has a strong resistance to moisture and oxygen, chloride (Cl), carbon dioxide (co2), etc. Corrosion resistance and organic resin bonding ability greatly increased performance. Its excellent surface physical and chemical properties will have a significant impact on applications.

In December 2013, the process by the sichuan, Chinese Academy of Sciences system test. The corrosion resistance of use 20 to 30 years in the Marine climate condition, can be widely used in wind power heikki. Surface bond strength more than 20 mpa, can be widely used in high-speed permanent magnet motor, special motor, electric car motor, ultra-high voltage, high voltage dc power supply system, a quick charging system, aerospace defense industry and other fields.


Application of editing

Sintered ndfeb permanent magnetic material

Scanning electron microscope in section 3010

Scanning electron microscope in section 3010

With excellent magnetic properties, it is widely used in the fields of electronics, power machinery, medical equipment, toys, packaging, hardware machinery, aerospace and aviation, etc. The more common are permanent magnet motors, loudspeakers, magnetic separators, computer disk drives, magnetic resonance imaging equipment and instruments.

Nano (Royce3010) chelate thin film coating processing can use 20 to 30 years in the Marine climate condition, can be widely used in wind power heikki. Surface bond strength more than 20 mpa, can be used widely in the high-speed permanent magnet motor, special motor, electric car motor, ultra-high voltage, high voltage dc power supply system, quick charging system, aerospace defense industry and other fields.


Chemical composition editing

Ndfeb permanent magnetic material is based on the intermetallic compound Nd2Fe14B.The main components are the rare earth elements neodymium (Nd), iron (Fe) and boron (B).Of rare earth elements mainly for neodymium (Nd), in order to obtain different performance available parts of dysprosium (Dy), praseodymium (Pr), and other rare earth metals, iron can also be cobalt (Co), aluminum (Al) and other metal parts replacement, boron content is smaller, but to form a square crystal structure between the metal compounds play an important role, make compounds with high saturation magnetization, high uniaxial anisotropy and high Curie temperature.

The third generation of rare-earth permanent magnet ndfeb is the most powerful permanent magnet in contemporary magnets. Its main raw materials are the rare-earth metal neodymium 29%-32.5%, metal element iron 63.95-68.65%, non-metal element boron 1.1-1.2%, dysprosium 0.6-8%, niobium 0.3-0.5%, aluminum 0.3-0.5%, copper 0.5-0.15% and other elements.


  1. Usually with a magnet of the same specification on a plane that can be adsorbed, such as: patch, blade, iron door, etc., with the handle to identify the size of the magnetic force
  2. Use electronic scale: the weak magnetic force of the magnet is generally related to its density, the density is small if the magnetic force is relatively small, the weight of the magnetic force is relatively large, on the contrary, the weight of the light magnetic force is small if the requirements on the magnet is relatively high, the need for instrument test.[1]

An overview of the

Each product is divided into several brands according to the maximum magnetic energy product

The brand names of ndfeb magnetic materials are: n35-n52, 35m-50m, 30h-48h, 30sh-45sh, 28uh-35uh, 28eh-35eh.

Example: 048021 represents the sintered ndfeb permanent magnetic material with (BH) Max of 366~398kj/m3 and Hcj of 800KA/m.

Brand by Lord said of sintered ndfeb permanent magnet materials and magnetic properties of 2 kinds of three parts, the first part is given priority to, according to the chemical symbol ND of neodymium, iron chemical symbol of FE and boron element, chemical symbol B, the second part is the line in front of the Numbers, is the material nominal value of the maximum magnetic energy product (BH) Max (in kj/m3), the third part to slash the number, the intensity of magnetic polarization coercive force value (unit for KA/m), one over ten of numerical adopts the nearest integer.

Example: ndfeb380/800 means (BH) Max is 366~398kj/m3,Hcj is 800KA/MR sintered ndfe-b permanent magnetic material.

Surface treatment of ndfeb:

  1. Phosphating;
  2. Inorganic salt passivation;
  3. Electroplating;
  4. Electrophoresis;
  5. Vacuum deposition;



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