With the development of modern industry and technology, the demand for rare earth permanent magnet materials is increasing. Rare earth permanent magnets have a wide range, including hard magnetic materials, soft magnetic materials, semi-hard magnetic materials, magnetostrictive materials, magneto-optical materials, magnetic bubble materials and magnetic refrigeration materials.
The properties of permanent magnets are mainly determined by the maximum magnetic energy product, saturated magnetization, cohesive force, remanence and Curie temperature.
Maximum Energy Product: The maximum energy product is the maximum of the product of the magnetic induction intensity and the magnetic field intensity on the demagnetization curve. The greater the value is, the greater the magnetic energy stored in the unit volume, the better the material performance is.
Saturation Magnetization: Saturation magnetization is a very important parameter for permanent magnetic materials. The higher the saturation magnetization is, the higher the maximum magnetic energy product and the upper limit of remanence is .
Coercive Force: After the ferromagnet is magnetized to saturation, the reverse external magnetic field required to reduce its magnetization or magnetic induction to zero is called coercive force. It represents the ability of materials to resist demagnetization.
Remainence: After the ferromagnet is magnetized to saturation and the external magnetic field is removed, the residual magnetization or residual magnetic induction strength retaining in the magnetization direction is called remanence.
Curie Temperature: The critical temperature at which a strong ferromagnet changes from ferromagnetism and ferromagnetism to paramagnetism is called Curie temperature or Curie point. A high temperature of Curie indicates that the use temperature of permanent magnetic materials is also high.