Transformer core and rare earth
According to sources, electronic transformer cores mainly use soft magnetic materials, while rare earths have relatively few applications in soft magnetics. However, rare earths are very important for the innovation and development of transformer cores.
For example, the iron core material of the so-called rare earth transformer is made of silicon steel sheet containing rare earth material. This kind of magnetic core has better magnetic permeability and lower magnetic loss.
The main components of ferrite also include iron oxide and rare earth element oxides. Ferrite magnetic materials can be divided into spinel type (MFe2O4); garnet type (R3Fe5O12); magnetoplumbite type (MFe12O19); perovskite type (MFeO3) according to their crystal structure. Among them, M refers to a divalent metal ion with an ion radius similar to Fe2+, and R is a rare earth element. According to different uses of ferrite, it can be divided into soft magnetism, hard magnetism, moment magnetism and piezoelectric magnetism.
In addition to ferrite, rare earth materials are also used in nanocrystalline soft magnetism. Nanocrystalline soft magnetic materials generally mean that the grain size in the material is reduced to the nanometer level (generally ≤50nm) to obtain high initial permeability (μi～105) and low coercivity (Hc～0.5A/m) s material. Generally, a small amount of Cu and Nb are added to Fe-B-Si-based alloys. After being made into amorphous materials, appropriate heat treatment is carried out. The functions of Cu and Nb are to increase the number of crystal nuclei and inhibit the growth of crystal grains. Ultra-fine (nano-level) grain structure. Nanocrystalline soft magnetic materials have very small magnetic anisotropy due to their special structure, magnetostriction tends to zero, and the resistivity is higher than that of crystalline soft magnetic alloys, but slightly lower than that of amorphous alloys, and has high magnetic flux density , Comprehensive excellent performance of high permeability and low iron loss.