Ndfeb magnetic strength is related to material and production process, such as related to the volume also.
For substances such as Fe, Co, Ni, magnetic susceptibility can be up to 10 - at room temperature
3 orders of magnitude, according to this kind of magnetic for ferromagnetic material.
Ferromagnetic material even in weak magnetic field, also can get high magnetization, and when to remove all the external magnetic field, can still keep strong magnetic.
Its magnetic susceptibility is positive, but when the field increases, due to the rapid reach saturation magnetization, the H smaller.
Ndfeb magnetic material has strong magnetic, mainly due to their strong internal exchange field.
The exchange of ferromagnetic material can be positive, and large, makes the adjacent atomic magnetic moment of the parallel orientation (
Corresponding to a steady state)
, many small area - is formed within the material
The magnetic domain.
There are about 1015 atoms each domain.
The magnetic moment of these atoms are arranged along the same direction, it is assumed that the crystal is very strong called 'molecular field' diamond, 'molecular field' to make each of the state of saturation magnetization of the magnetic domain automatically.
This kind of spontaneous magnetization is called spontaneous magnetization.
Because of its existence, ferromagnetic material is magnetized in the land of weak magnetic field is strong.
So spontaneous magnetization are the basic characteristics of ferromagnetic material, is also the difference of ferromagnetic material and magnetic material.
Ferromagnetic ferromagnetic only under a certain temperature, more than the temperature, material due to the internal thermal agitation damage electron spin magnetic moment of parallel orientation, thus spontaneous magnetization to 0, ferromagnetic disappear.
This is called the Curie point temperature.
Above the Curie point, the material is characterized by strong paramagnetism, its magnetic susceptibility and obey the Curie temperature of relationships -
Outside the law, type in C for Curie constant.
Ndfeb magnet is a variety, is the most widely application field of a powerful magnet, is called the king of magnetic, ndfeb, because the application area is different, so the magnet Bunsen requirements are different, so there is a model.
By far the most common is N35 types, and the corresponding requirements appear spirit N38 N40 N42 N45 N50, etc. , are the current domestic manufacturing is the highest N50, Japan can produce N52.
Ndfeb is used in different products at the same time need to heat resistance requirements, common N35 -
N50 heat resistance is 80 degrees.
The back is N35M - a little bit better
N50M heat resistance is 100 degrees, and the corresponding N35H -
N48H , N27SH-
Product N45SH, UH, EH, AH, summary the highest heat resistance can reach 230 degrees.
If USES the magnet heat resistance requirement can not meet the demagnetization phenomenon will occur.