Silicon carbide materials with good absorption performance in the 8.2-18 GHz band

Absorbing materialIt can effectively absorb electromagnetic waves, avoid electromagnetic wave reflection, and is widely used in military and other fields. Advanced Institute Technology has prepared a series of epoxy resin/silicon carbide/nickel composite materials using a simple and feasible mechanical mixing method and studied their absorbing properties. The results showed that when the proportion of epoxy resin was between 20 wt% and 30 wt%, the absorption performance of the epoxy resin/silicon carbide composite material was significantly improved with the increase of silicon carbide content; And in the case where epoxy resin accounts for 20 wt%Epoxy resin/silicon carbide/nickel composite materialAs the nickel content increases, the absorption performance of the composite material first improves and then deteriorates. The sample with a mass ratio of epoxy resin/silicon carbide/nickel of 2:7:1 has a minimum reflectivity of -13.26 dB and a bandwidth of about 1.65 GHz at a material thickness of 1 mm, which meets the basic requirements of absorbing materials and has the potential to become a high-performance absorbing material in the 8.2-18 GHz band.

Absorbing materials are a type of material that can dissipate electromagnetic wave energy or make electromagnetic waves disappear due to interference through mechanisms such as dielectric loss and magnetic loss, effectively avoiding the reflection of incident electromagnetic waves. They are of great significance for military, civilian and other fields. Whether used as stealth materials in the military industry for large combat weapons such as aircraft, ships, missiles, tanks, or in the civilian field to protect electronic equipment or ensure human health, the application of absorbing materials is very extensive. Therefore, absorbing materials have become a key type of material developed by various countries. Due to the frequency range of electromagnetic waves monitored by radar being generally between 2 and 18 GHz, most research on absorbing materials is focused on the frequency band of 2 to 18 GHz.

The study of absorbing materials usually uses reflectivity R (in dB) and a frequency band width of R<-10 dB to reflect the absorbing performance of absorbing materials: R reflects the degree of reflection of electromagnetic waves at the interface between absorbing materials and air, and the smaller the value, the better the absorbing performance; If R<-10 dB, it indicates that the material can absorb more than 90% of the electromagnetic wave energy, and it can be considered that the material effectively absorbs electromagnetic waves. The larger the bandwidth, the better the absorption performance. aboutSingle layer absorbing material， R can be represented by the complex dielectric constant and complex magnetic permeability using transmission line theory formulas (1) and (2) (where Z is the input impedance relative to free space, μ r and ε r are the complex magnetic permeability and complex dielectric constant, f is the electromagnetic wave frequency (in Hz), d is the material thickness (in mm), and c is the speed of vacuum light (taken as 2.997925 × 1011 mm/s)):

Z=μrεr−−√tanh(j2πfdcμrεr−−−−√)Z=μrεrtanh(j2πfdcμrεr)(1)

R(dB)=20log∣∣Z−1Z 1∣∣R(dB)=20log|Z−1Z 1|(2)

Absorbing materials can be classified into resistive, dielectric, and magnetic loss types based on the loss mechanism of electromagnetic waves. Resistive absorbing materials mainly absorb electromagnetic waves by dissipating heat through resistance, dielectric absorbing materials mainly absorb electromagnetic waves through dielectric loss mechanisms such as polarization relaxation, and magnetic loss absorbing materials mainly absorb electromagnetic waves through magnetic loss mechanisms such as hysteresis loss, eddy current loss, natural resonance loss, and domain wall resonance. Silicon carbide (SiC) is a dielectric type absorbing material that mainly relies on dielectric polarization loss to consume electromagnetic wave energy, and the loss mechanism is relatively complex.
Silicon carbide not only has adjustable absorption performance, but also has the characteristics of low density, high temperature resistance, and high strength, which is expected to achieve excellent properties such as lightweight and thin layer. Therefore, it has become a research focus in the field of absorbing materials. To further enhance the absorption performance of silicon carbide materials, the method of preparing composite materials by adding other materials is usually adopted to achieve this. Among them, by adding magnetic materials such as iron, cobalt, and nickel, silicon carbide composite materials can simultaneously exhibit both magnetic and dielectric losses, and are expected to obtain absorbing materials with good absorption performance.

In view of this, this study will use epoxy resin as a binder, mainly focusing on the absorption performance of epoxy resin/silicon carbide/nickel composite materials for X-band (8.2-12.4 GHz) and Ku band (12.4-18 GHz) electromagnetic waves. Advanced Institute Technology first explores the influence of silicon carbide content on the absorption performance of nickel free epoxy resin/silicon carbide composite materials, and then selects and fixes the optimal proportion of epoxy resin quality. Advanced Institute Technology studies the influence of nickel content on the absorption performance of epoxy resin/silicon carbide/nickel composite materials.