Glass powder / FeSiAl composite material with low-frequency wave-absorbing performance and preparation method of glass powder / FeSiAl composite material

Abstract

The invention discloses a glass powder / FeSiAl composite material with low-frequency wave absorbing performance. The glass powder / FeSiAl composite material is composed of a FeSiAl nanosheet and a glass phase wrapping the FeSiAl nanosheet. The invention also discloses a preparation method of the glass powder / FeSiAl composite material, which specifically comprises the following steps: uniformly mixing FeSiAl powder and glass powder, and calcining at 500-600 DEG C under the protection of inert gas to obtain the required composite material. According to the invention, an insulating glass phase is used as an isolation barrier layer, so that the Fe-Si-Al powder can be effectively prevented from forming a conductive path, the transportation of space carriers at a grain boundary is inhibited, the low-frequency dielectric loss is reduced, and interface polarization exists between different materials; the composite material has the minimum reflection loss of-56 dB at the frequency of 2.9 GHz, and the bandwidth (RL value is-10 dB) of the composite material can reach 4 GHz.

Description

Technical Field

[0001] The invention relates to a glass powder / FeSiAl composite material with low-frequency wave absorbing performance, and also relates to a preparation method of the glass powder / FeSiAl composite material. Background Art

[0002] The fifth generation of wireless communication technology is constantly developing, people are entering the smart era, and wireless devices are increasing in large numbers. Although 5G has greater advantages in communication than 4G, it will cause pollution in the low-frequency area due to its higher transmission power and lower utilization rate. The wavelength of the low-frequency band is longer, and the size of traditional absorption materials designed for the medium-frequency and high-frequency bands does not match it, making it difficult to absorb effectively. The electromagnetic parameters optimized by traditional absorption materials are not suitable for the low-frequency band and need to be readjusted for effective absorption.

[0003] Magnetic alloys mainly include elements such as iron and cobalt. They have high magnetic permeability and saturation magnetization and are widely considered to be the most promising low-frequency absorbers. However, the eddy current effect caused by their high conductivity leads to impedance mismatch, making it impossible to achieve high-performance low-frequency microwave absorption. When the impedance of the absorbing material does not match the impedance of free space, electromagnetic waves will be reflected on the surface of the material. For low-frequency microwave absorbing materials, designing appropriate impedance matching is the key to achieving effective absorption. If the impedance of the material differs too much from the impedance of free space, most of the incident low-frequency microwaves will be reflected back and cannot enter the material to be absorbed. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a glass powder / FeSiAl composite material with low-frequency absorbing performance, which has good absorbing performance in the low-frequency 2-3 GHz band; another purpose of the present invention is to provide a method for preparing the above-mentioned glass powder / FeSiAl composite material.

[0005] Technical solution: The glass powder / FeSiAl composite material with low-frequency wave absorbing performance described in the present invention is composed of FeSiAl nanosheets and a glass phase wrapped outside the FeSiAl nanosheets.

[0006] The preparation method of the glass powder / FeSiAl composite material is specifically as follows: FeSiAl powder and glass powder are uniformly mixed, and calcined at 500-600° C. under the protection of an inert gas to obtain the desired composite material.

[0007] Wherein, the FeSiAl powder is FeSiAl with a nano-sheet structure.

[0008] Wherein, the melting point of the glass powder is lower than the calcination temperature.

[0009] Wherein, the added amount of the glass powder is 10-40% of the total added amount of materials.

[0010] Wherein, the calcination temperature is 550°C.

[0011] Wherein, the insulation time is 5 to 6 hours.

[0012] Compounding FeSiAl with the glass phase and co-firing the flaky FeSiAl alloy powder and the glass phase can effectively inhibit the formation of impurity phases in the system, improve product purity, improve material properties and enhance process controllability; at the same time, using the insulating glass phase as an isolation barrier layer can effectively block the conductive path formed by the stacking of iron silicon aluminum nanosheets, inhibit the transport of spatial carriers at the grain boundaries, thereby reducing low-frequency dielectric losses and further reducing impedance mismatch.

[0013] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: since the dielectric loss of the magnetic material sheet-shaped sendust is higher than the magnetic damage, impedance mismatching occurs; the present invention uses an insulating glass phase as an isolation barrier layer, which can effectively block the sendust powder from forming a conductive path, inhibit the transport of space carriers at the grain boundary, thereby reducing low-frequency dielectric loss, and there is interface polarization between different materials, thereby improving absorption performance; the composite material of the present invention has a minimum reflection loss of -56dB at 2.9GHz, and its bandwidth (RL value is -10dB) can reach 4GHz. The present invention can control the effective absorption range of electromagnetic waves of the material at low frequency, thereby achieving strong reflection loss in the low-frequency band, so that it can be applied to the scene of long-distance radar detection of stealth. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Electromagnetic parameters of composite materials and FeSiAl prepared in Examples 1 to 3; wherein (a) is flaky FeSiAl; (b) is 10wt% glass powder / FeSiAl composite material in Example 1; (c) is 20wt% glass powder / FeSiAl composite material in Example 2; (d) is 30wt% glass powder / FeSiAl composite material in Example 3;

[0015] Figure 2 The reflection loss of the composite materials and FeSiAl prepared in Examples 1 to 3; wherein (a) is flaky FeSiAl; (b) is the 10wt% glass powder / FeSiAl composite material of Example 1; (c) is the 20wt% glass powder / FeSiAl composite material of Example 2; (d) is the 30wt% glass powder / FeSiAl composite material of Example 3;

[0016] Figure 3 is the loss tangent value of the composite material and FeSiAl obtained in Examples 1 to 3;

[0017] Figure 4 is the SEM image of FeSiAl powder;

[0018] Figure 5 This is a SEM image of the glass powder / FeSiAl composite material of Example 2;

[0019] Figure 6 This is the EDS image of the glass powder / FeSiAl composite material of Example 2. DETAILED DESCRIPTION

[0020] Example 1

[0021] The preparation method of the glass powder / FeSiAl composite material of the present invention comprises the following steps:

[0022] (1) FeSiAl powder and glass powder are mixed in a mass ratio of 9:1; in order to ensure uniform mixing, the powder is refined by grinding;

[0023] (2) Under nitrogen protection, the mixed powder is placed in a furnace and heated to 550 degrees Celsius; at this temperature, the powder is kept warm and heated for 5 hours; this step can form defects in FeSiAl, further improving the microwave absorption performance of the material, and can also promote the reaction between FeSiAl and glass powder to form a composite powder with the desired properties;

[0024] (3) After the insulation is completed, the furnace temperature is gradually lowered to cool the powder to room temperature; the cooled powder is ground to obtain the desired powder sample.

[0025] Example 2

[0026] The preparation method of the glass powder / FeSiAl composite material of the present invention comprises the following steps:

[0027] (1) FeSiAl powder and glass powder are mixed in a mass ratio of 8:2; in order to ensure uniform mixing, the powder is refined by grinding;

[0028] (2) Under nitrogen protection, the mixed powder is placed in a furnace and the temperature is raised to 550 degrees Celsius; at this temperature, the powder is kept warm for 5 hours to obtain a composite powder;

[0029] (3) After the insulation is completed, the furnace temperature is gradually lowered to cool the powder to room temperature; the cooled powder is ground to obtain the desired powder sample.

[0030] Example 3

[0031] The preparation method of the glass powder / FeSiAl composite material of the present invention comprises the following steps:

[0032] (1) FeSiAl powder and glass powder are mixed in a mass ratio of 7:3; in order to ensure uniform mixing, the powder is refined by grinding;

[0033] (2) Under nitrogen protection, the mixed powder is placed in a furnace and the temperature is raised to 550 degrees Celsius; at this temperature, the powder is kept warm for 5 hours to obtain a composite powder;

[0034] (3) After the insulation is completed, the furnace temperature is gradually lowered to cool the powder to room temperature; the cooled powder is ground to obtain the desired powder sample.

[0035] Example 4

[0036] The preparation method of the glass powder / FeSiAl composite material of the present invention comprises the following steps:

[0037] (1) FeSiAl powder and glass powder are mixed in a mass ratio of 6:4; in order to ensure uniform mixing, the powder is refined by grinding;

[0038] (2) Under nitrogen protection, the mixed powder is placed in a furnace and the temperature is raised to 550 degrees Celsius; at this temperature, the powder is kept warm for 5 hours to obtain a composite powder;

[0039] (3) After the insulation is completed, the furnace temperature is gradually lowered to cool the powder to room temperature; the cooled powder is ground to obtain the desired powder sample.

[0040] The microstructure and performance of the glass powder / FeSiAl composite materials prepared in Examples 1 to 4 were characterized.

[0041] Figure 1 The electromagnetic parameters of the composite materials of Examples 1 to 3 and the sheet FeSiAl are shown in Figure 2. When the glass phase doping amount is 20wt%, the real part of the dielectric constant of the glass powder / FeSiAl composite material is between 10 and 12, the imaginary part of the dielectric constant is between 0.5 and 2, the real part of the magnetic permeability is between 1.5 and 3.5, and the imaginary part of the magnetic permeability is between 0.5 and 2. Doping with glass powder reduces the dielectric constant, slightly reduces the magnetic permeability, and improves the impedance matching.

[0042] Figure 2The reflection loss diagram of the composite materials of Examples 1 to 3 and the sheet FeSiAl is shown below. When the glass phase doping amount is 20wt% and the filling ratio of the glass powder / FeSiAl composite material in paraffin is 70%, the wave absorption performance in the low-frequency band is the best: when the thickness is 5.9mm, it has a minimum reflection loss of -56dB at 2.9GHz, and its bandwidth (RL value is -10dB) can reach 4GHz.

[0043] Figure 3 The loss tangent values ​​of the composite materials and FeSiAl prepared in Examples 1 to 3. With the addition of the glass phase, the dielectric tangent value shows a gradually increasing trend with the increase of the doping amount, and the magnetic loss tangent value shows a gradually decreasing trend with the increase of the doping amount, indicating that the dielectric loss plays a leading role.

[0044] Scanning electron microscopy observations revealed that Figure 4 It can be clearly seen that the sendust powder used in the present invention presents a unique flake morphology. Figure 5 It can be observed that the glass phase is successfully doped into the FeSiAl powder, and the FeSiAl nanosheets are wrapped with a glass phase layer without affecting their sheet structure.

[0045] Figure 6 This is an energy dispersive X-ray spectroscopy (EDS) image of the glass powder / FeSiAl composite material prepared in Example 2. Through the elemental characterization analysis of the image, it can be clearly observed that the glass phase (the main component is lead oxide) is successfully doped and uniformly distributed in the composite material (FeSiAl nanosheet surface).

Claims

1. A glass powder / FeSiAl composite material with low-frequency wave absorbing performance, characterized in that: It is composed of FeSiAl nanosheets and a glass phase wrapped around the FeSiAl nanosheets.

2. The method for preparing the glass powder / FeSiAl composite material according to claim 1, characterized in that: Specifically, FeSiAl powder and glass powder are mixed evenly, and calcined at 500-600° C. under the protection of inert gas to obtain the desired composite material.

3. The method for preparing the glass powder / FeSiAl composite material according to claim 2, characterized in that: The FeSiAl powder is FeSiAl with a nano-sheet structure.

4. The method for preparing the glass powder / FeSiAl composite material according to claim 2, characterized in that: The melting point of the glass powder is lower than the calcination temperature.

5. The method for preparing the glass powder / FeSiAl composite material according to claim 2, characterized in that: The amount of the glass powder added is 10-40% of the total amount of the materials added.

6. The method for preparing the glass powder / FeSiAl composite material according to claim 2, characterized in that: The calcination temperature is 550-560°C.

7. The method for preparing the glass powder / FeSiAl composite material according to claim 2, characterized in that: The insulation time is 5 to 6 hours.

8. The method for preparing the glass powder / FeSiAl composite material according to claim 2, characterized in that: The inert gas is nitrogen or argon.

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