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Most useful knowledge base of NdFeB magnet (rare earth magnet)

nicked coated neodymium magnets disc shape

Basic Knowledge

  1. Definition: rare earth permanent magnet based on Nd2Fe14B intermetallic compound. It has a tetragonal crystal structure, strong magnetocrystalline anisotropy and high saturation magnetization.
ElementRatio
Neodymium (Nd)25 – 35%
Iron (Fe)65 – 75%
Boron (B)1%
The element ratio can be adjusted according to the specific requirements of magnetic property. Other elements can also be added in order to improve its performance.
sintered ndfeb magnets

2. Features:

Advantages: extremely high magnetic energy product and coercive force (Hc), high energy density, high cost performance, and good mechanical properties

Disadvantages: low curie temperature, low max. working temperature, and easy to pulverize and corrode without coating

The neodymium iron boron permanent magnet material is a permanent magnet material based on the intermetallic compound Nd2Fe14B. Compared with cast AlNiCo permanent magnet materials and ferrite permanent magnet materials, neodymium iron boron has extremely high magnetic energy product and coercive force, which can lift 640 times of its own weight.

The King of permanent magnets

Permanent magnet refers to materials that have wide hysteresis loops, high coercivity, and high remanence, and can maintain constant magnetic properties once they are magnetized, also known as hard magnetic materials.

Rare earth neodymium iron boron material is called “the king of permanent magnets”. It was developed independently in 1982 by Sumitomo Special Metal Materials (Japan) and General Motors Corporation (the US) and realized mass production in 1983. So far, three generations of permanent magnet materials have been commercialized on a large scale.

  • The first generation is a 1:5 compound composed of rare earth atoms and cobalt atoms, referred to as RECo5, represented by SmCo5.
  • The second generation is a rare earth permanent magnet alloy based on a compound composed of rare earth atoms and cobalt atoms in a ratio of 2:17, referred to as RE2Co17.
  • The third generation is a rare earth-iron-boron permanent magnet material, which mainly contains intermetallic compounds of rare earth and iron elements. It is a high-performance and practical permanent magnet material that does not contain cobalt. It’s made of neodymium iron boron (NdFeB). Also known as neodymium magnet, it has become the mainstream of a new generation of high-performance permanent magnet materials

magnetic properties of different permanent magnets
Comparison of magnetic properties of different permanent magnetic materials

Classification of NdFeB magnets

There are two main types of neodymium iron boron (Nd-Fe-B): sintered NdFeB magnets and bonded NdFeB magnets. In comparison, sintered NdFeB magnet is much important in terms of application, performance and output. It is not to say that the market value of bonded NdFeB magnet is lower than that of sintered NdFeB magnet. For some specific applications, only bonded NdFeB magnets can meet the requirements.

Markte applications

Sintered NdFeB magnet has high magnetic energy product, high coercivity. It is mainly used in large and medium-sized electric machines, high-fidelity speakers, magnetic separators or filters, consumer electronics, etc.

The magnetic properties of bonded NdFeB magnet are not as good as sintered NdFeB magnet, but it has the advantages of flexibility in shapes and magnetization, low cost, high precision, uniform and stable magnetic field, etc. It is irreplaceable in the fields of information technology, office automation, consumer electronics, etc.

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