Permanent magnetic materials based on rare earth iron boron tetragonal compounds mainly refer to neodymium iron boron permanent magnetic materials (NdFeB magnet), also referred to as neodymium magnets.
The following is a detailed introduction to this permanent magnetic material:
1. Basic Overview
Name: Neodymium iron boron permanent magnetic material, also known as neodymium magnet or NdFeB magnet.
Discoverer: In 1982, it was discovered by Masato Sagawa of Sumitomo Special Metals of Japan.
Chemical formula: Nd2Fe14B, a tetragonal crystal formed by neodymium (Nd), iron (Fe), and boron (B).
Features: Neodymium iron boron magnet is the permanent magnet with the second highest magnetic property after absolute zero holmium magnet, and is also the most commonly used rare earth magnet. Its magnetic energy product (BHmax) is greater than that of samarium cobalt magnet, and it was the material with the largest magnetic energy product in the world at that time.
2. Main components and properties
Main components: rare earth element neodymium (Nd), metal element iron (Fe), and non-metal element boron (B). In order to obtain different properties, neodymium can be partially replaced by other rare earth metals such as dysprosium (Dy) and praseodymium (Pr), and iron can also be partially replaced by other metals such as cobalt (Co) and aluminum (Al).
Performance: It has high saturation magnetization, high uniaxial anisotropy and high Curie temperature. Its remanence, coercivity and maximum magnetic energy product are all excellent.
3. Classification
NdFeB permanent magnet materials are mainly divided into the following types according to different production processes:
Sintered NdFeB: It is smelted after air flow grinding and powdering. It has a high coercivity value and extremely high magnetic properties. The maximum operating temperature of high-performance products can reach 200 degrees Celsius, but it is easy to corrode and the surface needs to be plated.
Bonded NdFeB: NdFeB powder is evenly mixed with a binder such as resin, plastic or low melting point metal, and then a composite NdFeB permanent magnet is made by compression, extrusion or injection molding. It has magnetism in all directions, good corrosion resistance and good temperature stability.
Injection molded NdFeB: With extremely high precision, it is easy to make thin-walled rings or thin magnets with complex anisotropic shapes.
4. Application fields
Due to its excellent magnetic properties, NdFeB permanent magnet materials are widely used in many fields:
Electronic products: such as hard disks, mobile phones, headphones, and battery-powered tools.
Electrical machinery: used to manufacture permanent magnet motors, etc.
Medical equipment: such as magnets in magnetic resonance imaging equipment.
Others: also used in toys, packaging, hardware machinery, aerospace and other fields, as well as computer disk drives, magnetic separators and other equipment.
5. Surface treatment and protection
In order to avoid corrosion damage, NdFeB permanent magnet materials need to be protected on their surfaces when used. Common surface treatment methods include electroplating, electrophoresis, vacuum vapor deposition, chemical plating, organic spraying, etc.
In addition, nano-chelate film coating-free treatment is also an advanced surface treatment method that can meet the needs of long-term use in specific environments (such as marine climate conditions).
In summary, the permanent magnet material based on rare earth iron boron tetragonal compound - NdFeB permanent magnet material, plays an important role in modern industry and science and technology with its excellent magnetic properties and wide application fields.