Absorbing material refers to a type of material that can absorb the electromagnetic wave energy projected on its surface. In engineering applications, the requirements for absorbing materials are very high. In addition to the high absorption rate of electromagnetic waves in a wide frequency band, the absorbing materials are also required to have the properties of light weight, temperature resistance, humidity resistance, and corrosion resistance.
With the development of modern science and technology, the influence of electromagnetic wave radiation on the environment is increasing. At the airport, the flight is delayed due to electromagnetic wave interference; in the hospital, mobile phones often interfere with the normal operation of various electronic diagnosis and treatment equipment. Therefore, the treatment of electromagnetic pollution and the search for a material that can withstand and weaken electromagnetic wave radiation-absorbing materials have become a major issue in materials science.
Electromagnetic radiation causes direct and indirect damage to the human body through thermal, non-thermal, and cumulative effects. Studies have confirmed that the ferrite absorbing material has excellent performance, and it has the characteristics of high absorption frequency band, high absorption rate, and thin matching thickness. Applying this material to electronic equipment can absorb leaked electromagnetic radiation and achieve the purpose of eliminating electromagnetic interference. According to the law of electromagnetic waves propagating in the medium from low magnetic to high magnetic permeability, high magnetic permeability ferrite is used to guide electromagnetic waves, through resonance, a large amount of radiant energy of electromagnetic waves is absorbed, and then the energy of electromagnetic waves is converted into heat energy through coupling.
The loss mechanism of absorbing materials can be roughly divided into the following categories: 1 resistive loss
This kind of absorption mechanism is related to the resistive loss related to the conductivity of the material, that is, the greater the conductivity, the greater the macro current (including the current caused by the electric field change and the eddy current caused by the magnetic field change) caused by the carrier, which is beneficial to electromagnetic energy. Converted into heat energy.
2 Dielectric loss
It is a kind of dielectric loss absorption mechanism related to the electrode, that is, the electromagnetic energy is converted into heat and energy consumption is dissipated by the "friction" effect generated by the repeated polarization of the medium. The dielectric polarization process includes: electron cloud displacement polarization, polar dielectric moment turning polarization, electric ferrite domain turning polarization, and wall displacement.
3 Magnetic loss
This kind of absorption mechanism is a kind of magnetic loss related to the dynamic magnetization process of ferromagnetic medium. This kind of loss can be refined into: hysteresis loss, gyromagnetic eddy current, damping loss and magnetic aftereffect, etc. The main sources are and Magnetic domain turning, magnetic domain wall displacement, and natural resonance of magnetic domains with similar hysteresis mechanisms. In addition, the microwave loss mechanism of nanomaterials is a hot spot in the analysis of absorbing materials today.