Ferrite Core: Application and Development of New Magnetic Materials

Ferrite core is a magnetic material with high permeability, low hysteresis, low loss, and superior high-frequency performance. This article mainly introduces the basic principle, characteristics, preparation methods, application fields, and future development trends of ferrite cores.

1、 The basic principles and characteristics of ferrite magnetic cores

1. Basic Principles

Ferrite core is a soft magnetic material, mainly composed of iron and oxygen. Its basic structure is Fe3O4, also known as magnetic iron oxide. The magnetism of ferrite materials comes from the spin magnetic moment of its internal iron ions. Under the action of an external magnetic field, the spin magnetic moment of iron ions changes, resulting in magnetic permeability.

2. Characteristics

(1) High magnetic permeability: Compared with other soft magnetic materials, ferrite cores have higher magnetic permeability, which can effectively improve the efficiency of electromagnetic energy conversion;

(2) Low hysteresis: The hysteresis loss under the action of a magnetic field is lower, which is beneficial for reducing the thermal loss of magnetic components;

(3) Low loss: The ferrite core has lower loss during high-frequency operation, which is beneficial for improving the efficiency of electromagnetic components;

(4) Superior high-frequency performance: The ferrite core has good stability and reliability during high-frequency operation.

2、 Preparation method of ferrite magnetic core

(1) Ceramic method: The ferrite magnetic core is made by mixing iron oxide with other additives, grinding, pressing and forming, sintering and other processes; (2) Sol gel method: It is made from organometallic compounds by hydrolysis, gel, drying, pyrolysis and other processes; (3) Co precipitation method: using iron salt solution as raw material, adjusting the pH value by adding alkaline substances to precipitate iron ions, and preparing through processes such as washing, drying, and sintering.

Optimization of preparation process

1. Choosing suitable raw materials: Using high-purity iron oxide raw materials can reduce the impact of impurities and improve the magnetic properties of magnetic cores. In addition, by selecting additives reasonably, the performance of ferrite cores can be improved, such as increasing saturation magnetic induction intensity and reducing hysteresis loss.

2. Powder treatment: Powder treatment includes processes such as grinding, dispersion, and drying. By optimizing these processes, the particle size distribution and morphology of the powder can be improved, and the density and magnetic performance of the magnetic core can be enhanced. For example, using wet grinding can reduce friction between magnetic particle particles and lower the rate of magnetic particle damage; Drying powder with good fluidity and easy molding can be obtained by spray drying.

3. Forming process: The forming process includes compression molding, injection molding, extrusion molding, etc. By optimizing the molding process, the shape accuracy and density of the magnetic core can be improved, and the preparation cost can be reduced. For example, using isostatic pressing can obtain magnetic cores with high density and uniformity; The preparation of complex shaped magnetic cores can be achieved through injection molding and extrusion molding.

4. Sintering process: Sintering process is a crucial step in the preparation of ferrite magnetic cores, and its parameters such as temperature, atmosphere, and time have important effects on the microstructure and properties of the magnetic cores. By optimizing the sintering process, the hysteresis loss of the magnetic core can be reduced, and the magnetic permeability can be improved. For example, the two-step sintering method can reduce the grain size of the magnetic core and improve its magnetic performance; Using a protective atmosphere sintering can reduce the precipitation of oxides and reduce the loss of magnetic cores.

5. Post processing technology: Post processing technology includes cutting, magnetization, coating, etc. By optimizing the post-processing technology, the performance and service life of magnetic cores can be improved. For example, using laser cutting can reduce edge damage of magnetic cores and improve their dimensional accuracy; Magnetization treatment can arrange the magnetic domains of the magnetic core in an orderly manner in one direction, thereby improving magnetic properties; Coating a protective layer can improve the corrosion resistance and wear resistance of magnetic cores, and extend their service life.