Material with high-temperature wave-absorbing heat-insulating coating and preparation method thereof

Abstract

This invention relates to a material with a high-temperature microwave absorbing and heat-insulating coating and its preparation method, belonging to the field of microwave absorbing materials technology. The material with the high-temperature microwave absorbing and heat-insulating coating provided by this invention is prepared by mechanically mixing lanthanum magnesium aluminum oxide (LAMA) powder and samarium iron nitride (SmFeN) powder, and then spraying the mixed powder onto the surface of a substrate using plasma spraying. This invention exhibits good microwave absorption and heat insulation performance even at temperatures ranging from room temperature to high temperatures (20-990℃), with a reflectivity in the 8-12GHz frequency band and a relatively small thickness. The materials and preparation method involved in this invention have simple process steps, generate no harmful or toxic pollutants during the process, and have good environmental compatibility.

Description

Technical Field

[0001] This invention belongs to the field of microwave absorbing materials technology, and relates to a material with a high-temperature microwave absorbing and heat-insulating coating and its preparation method. Background Technology

[0002] With the continuous development of technologies such as wireless communication, radar detection, and electromagnetic wave shielding, microwave absorbing materials, as an important type of material, are widely used in military, aviation, aerospace, communications, and electronics fields. Traditional microwave absorbing materials are mainly composed of carbon and alloy powders, possessing excellent absorption properties. However, under certain high-temperature environments, traditional microwave absorbing materials often lose their absorption effect, thus failing to meet practical requirements. Therefore, developing a material that can maintain good microwave absorption performance under high-temperature environments is of significant practical importance.

[0003] In recent years, researchers have begun exploring and developing materials with high-temperature electromagnetic wave absorption properties. Among these, some high-temperature ceramic materials are widely used in high-temperature absorption applications. For example, calcium aluminate, silicon nitride, and alumina have attracted widespread attention due to their excellent high-temperature stability and good absorption performance. Furthermore, nanocomposite materials are also considered a potential high-temperature absorption material. These materials, composed of nanoparticles and a matrix material, possess excellent absorption performance and high-temperature stability, and can be used for high-temperature electromagnetic wave shielding and absorption applications.

[0004] Based on these background technologies, this invention proposes a material with a high-temperature microwave absorbing and heat-insulating coating—a samarium iron nitrogen / lanthanum magnesium aluminum oxide (SmFeN / LAMA) composite material—and outlines the corresponding preparation process and material composition. This material maintains its microwave absorption effect in the 1-18 GHz frequency band across a temperature range from room temperature to high temperatures (20-990℃), exhibiting excellent high-temperature stability and absorption performance. It can effectively absorb electromagnetic waves under high-temperature conditions, meeting the microwave absorption and heat insulation requirements in high-temperature environments, and thus possesses high practical value. Summary of the Invention

[0005] This invention provides a heat-insulating coating material with high-temperature microwave absorption performance and its preparation method. The resulting material has good broadband microwave absorption performance, and the preparation method is low in cost, simple in structure, easy in process, and easy to control in process parameters.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A material with a high-temperature microwave-absorbing and heat-insulating coating, consisting of a sheet material and a surface coating;

[0008] The sheet material is a metal sheet or a sheet material made of other materials, wherein the metal sheet is one of cold-rolled sheet, hot-dip galvanized sheet, aluminized sheet, high-aluminum alloy sheet, or stainless steel sheet.

[0009] The surface coating has a thickness of 0.2-4 mm; the coating is composed of lanthanum magnesium aluminum oxide (LAMA) powder and samarium iron nitrogen (SmFeN) powder; wherein the mass ratio of lanthanum magnesium aluminum oxide (LAMA) powder to samarium iron nitrogen (SmFeN) powder is LAMA:SmFeN=(0.5-5):1.

[0010] The samarium iron nitrogen powder is in flake form, with an average particle size of approximately 10 nm to 70 μm.

[0011] The lanthanum magnesium aluminum oxide powder is in granular form and has been ball-milled using a high-energy ball mill, with an average particle size of 1 nm-2 μm.

[0012] A method for preparing a high-temperature microwave absorbing and heat-insulating coating material includes the following steps:

[0013] S1 mechanically mixes lanthanum magnesium aluminum oxide (LAMA) powder and samarium iron nitrogen (SmFeN) powder to obtain a mixed powder of LAMA and SmFeN;

[0014] S2 puts the mixed powder into the spray gun and sprays the mixed powder evenly onto the surface of the board to obtain a material with a high-temperature microwave absorbing and heat-insulating coating.

[0015] In S1, the mechanical mixing is performed using either ball milling or oscillation.

[0016] In S2, plasma spraying is used, and argon gas protection is required during spraying. The working gas flow rate is 30-50L / min, and the spraying power is 10-60kW.

[0017] The substrate needs to be pre-sanded before spraying.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1. High Temperature Resistance: The heat-insulating coating of this invention maintains good wave absorption performance in the high temperature and high frequency range (20-990℃, 1-18GHz). This characteristic is particularly important in high-temperature environments, such as the aerospace field, where it can protect electronic equipment and structures from damage caused by high temperatures.

[0020] 2. Thickness Advantage: Compared with some traditional microwave absorbing materials, the coating of this invention can still exhibit good microwave absorption performance with a smaller thickness. This reduces the amount of material used, which helps in lightweight design and can save costs.

[0021] 3. Simple preparation method: The preparation method of the present invention is relatively simple, with fewer process steps, and does not require complex equipment and process conditions, which reduces the difficulty of production and improves the preparation efficiency.

[0022] 4. Environmentally friendly: The preparation process does not generate harmful or toxic pollutants and has good environmental compatibility. This helps reduce the negative impact of the manufacturing process on the environment and meets modern environmental protection requirements.

[0023] 5. Low cost: The materials used are relatively inexpensive, and the manufacturing cost is relatively low, which makes this heat insulation coating competitive in large-scale applications such as electromagnetic shielding and radar stealth technology.

[0024] 6. Broad Application Prospects: Due to its superior wave absorption and heat insulation properties, the coating of this invention can be widely used in many fields, including communications, defense, automotive manufacturing, and energy. This increases its commercial potential and market opportunities. Attached Figure Description

[0025] Figure 1 This is a flowchart of the process for preparing heat-insulating coating materials.

[0026] Figure 2 This is a SEM image of SmFeN powder.

[0027] Figure 3 This is a SEM image of LAMA powder.

[0028] Figure 4 This is a SEM image of a mixture of LAMA and SmFeN powder.

[0029] Figure 5 This is a graph showing the change in reflectivity of the absorbing material obtained in Example 1 at different temperatures as a function of frequency.

[0030] Figure 6 This is the cross-section of the sample obtained after spraying in Example 1.

[0031] Figure 7 This is the surface of the sample after spraying obtained in Example 1.

[0032] Figure 8 This is a graph showing the change in reflectivity of the absorbing material obtained in Example 3 as a function of frequency. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, wherein the preparation process of the heat-insulating coating material is as follows: Figure 1 As shown. Unless otherwise specified in the examples, conditions should be followed according to standard conditions or the manufacturer's recommendations. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0034] Example 1

[0035] The high-temperature resistant microwave absorbing material and its preparation method provided by this invention include the following steps:

[0036] Prepare the required materials: lanthanum magnesium aluminum oxide (LAMA) powder and samarium iron nitrogen (SmFeN) powder. The specific compositions are shown in Tables 1 and 2, respectively. Figure 2 It can be seen that SmFeN has a sheet-like structure with an average size of 100 μm * 80 μm. (From...) Figure 3 It can be seen that LAMA has a spherical structure with an average diameter of 2 μm.

[0037] LAMA powder and SmFeN powder were mixed at a mass ratio of 2:1.

[0038] The powders were mechanically mixed using a ball milling method to ensure thorough and uniform mixing.

[0039] Place the mixed powder into the spray gun and introduce argon gas for protection.

[0040] Place the sheet material to be protected under the spraying machine, start the spraying machine, and spray the 10cm*10cm stainless steel sheet until the coating thickness is 2mm. Figure 6 As shown. Ensure the mixed powder is sprayed evenly onto the surface of the board, such as... Figure 7 As shown.

[0041] Table 1. Element content of LAMA alloy

[0042]

[0043] Table 2. Element content of SmFeN alloy

[0044]

[0045] The coated substrate was slowly heated to simulate the actual heating rate, with temperatures raised to 40℃, 150℃, 300℃, 900℃, and 990℃ respectively. Electromagnetic wave reflectivity tests were then conducted under an arched beam at 8-12 GHz. The test results are as follows: Figure 5 As shown.

[0046] Example 2

[0047] In this embodiment, different substrates are used to prepare the high-temperature microwave absorbing and heat-insulating coating. In addition to stainless steel sheets, aluminum alloy sheets and ceramic substrates can also be used. The preparation method is the same as described in Example 1, except that when the substrate is an aluminum alloy sheet, the plasma spraying power is 30kW; when the substrate is a ceramic substrate, the plasma spraying power is 40kW.

[0048] Example 3

[0049] The difference between this embodiment and Example 1 lies in the mass ratio of lanthanum magnesium aluminum oxide (LAMA) powder to samarium iron nitrogen (SmFeN) powder. Specifically, the mass ratio of LAMA to SmFeN is 1:1, resulting in coating thicknesses of 1.5 mm, 1.75 mm, 2 mm, and 3 mm for the obtained microwave absorbing materials.

[0050] The absorbing material obtained in Example 1 was observed using a scanning electron microscope (SEM), and the resulting SEM image is shown below. Figure 4 As shown. By Figure 4 It can be seen that SmFeN and LAMA are evenly mixed and distributed.

[0051] The high-temperature microwave absorption performance of the microwave absorbing material obtained in Example 1 was determined. The method is as follows:

[0052] The absorption performance of the sample was measured using a vector network analyzer with an arc-shaped beam test. The results are as follows: Figure 5 As shown in the figure, the sample still has wave absorption performance at a high temperature of 990℃. The minimum reflection loss value is less than -6dB. In the range of 14.5-18GHz, the reflection loss value is less than -2dB. In the range of 16-18GHz, the reflection loss value is less than -6dB.

[0053] The absorption performance of the sample was measured using a vector network analyzer with a coaxial loop, and the results are as follows: Figure 8 As shown in the figure, the reflection loss curves of different coating thicknesses at room temperature are displayed under the condition that the mass ratio of LAMA to SmFeN is 1:1. The 3 mm thickness has the best reflectivity and the reflection loss value is about -11 dB, which corresponds to a frequency value of about 9.5 GHz. At the same time, the reflection loss values ​​measured by the coaxial method in the range of 12 to 18 GHz are in good agreement with the reflection loss values ​​of the samples measured by the bow beam.

[0054] In summary, the method for preparing the microwave absorbing material provided in this application is simple, feasible, and can be continuously produced with low production costs. It can significantly improve the temperature resistance and high-temperature microwave absorption performance of the microwave absorbing material. The microwave absorbing material prepared by this method has excellent high-temperature resistance and stable microwave absorption performance, and can still maintain good microwave absorption performance from room temperature to 990℃.

Claims

1. A material with a high-temperature microwave absorbing and heat-insulating coating, characterized in that, Achieve wave absorption effect in the 20-990℃ and 1-18GHz frequency band; The material consists of a sheet and a surface coating, wherein the sheet is a metal sheet or a sheet made of other materials, and the surface coating is made of lanthanum magnesium aluminum oxide powder and samarium iron nitrogen powder; The surface coating thickness is 0.2-4 mm; the mass ratio of lanthanum magnesium aluminum oxide powder to samarium iron nitrogen powder is lanthanum magnesium aluminum oxide powder : samarium iron nitrogen powder = (0.5-5): 1; The samarium iron nitrogen powder is in flake form, with an average particle size of 10 nm-70 μm; The lanthanum magnesium aluminum oxide powder is in granular form and has been ball-milled using a high-energy ball mill, with an average particle size of 1 nm-2 μm.

2. The material with a high-temperature microwave absorbing and heat-insulating coating according to claim 1, characterized in that, The metal sheet is selected from one of the following: cold-rolled sheet, hot-dip galvanized sheet, aluminized sheet, high-aluminum alloy sheet, and stainless steel sheet.

3. A method for preparing a material with a high-temperature microwave absorbing and heat-insulating coating according to claim 1 or 2, characterized in that, Includes the following steps: S1 mechanically mixes lanthanum magnesium aluminum oxide powder and samarium iron nitrogen powder to obtain a mixed powder of lanthanum magnesium aluminum oxide and samarium iron nitrogen; S2 puts the mixed powder into the spray gun and sprays the mixed powder evenly onto the surface of the board to obtain a material with a high-temperature microwave absorbing and heat-insulating coating.

4. The method for preparing a material with a high-temperature microwave absorbing and heat-insulating coating according to claim 3, characterized in that, In step S1, the mechanical mixing is performed using either ball milling or oscillation.

5. A method for preparing a material with a high-temperature microwave absorbing and heat-insulating coating according to claim 3, characterized in that, In step S2, plasma spraying is used, and argon gas is required for protection during spraying. The working gas flow rate is 30-50L / min, and the spraying power is 10-60kW. The substrate needs to be pre-sanded before spraying.

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