A simple method for in-situ synthesis of FeSi@SiC high-temperature-resistant wave-absorbing material

Abstract

The application belongs to the technical field of wave-absorbing materials, and particularly relates to a simple method for in-situ synthesis of FeSi@SiC high-temperature-resistant wave-absorbing material. The method comprises the following steps: dissolving Fe(NO3)3.9H2O in anhydrous ethanol, adding SiC powder, stirring, evaporating anhydrous ethanol in the solution, and heating to remove the combined water in the solid; grinding the solid after the combined water is removed into a powder sample, adding Fe powder and KCl, mixing uniformly, and performing reduction treatment; grinding the reduced solid powder thoroughly, adding hydrochloric acid solution, filtering, washing, and drying to obtain FeSi@SiC. The FeSi@SiC material is in-situ synthesized by the impregnation reduction method in one step, the preparation method is simple, the obtained FeSi@SiC material has high-temperature resistance and wave-absorbing performance, the physical properties do not change under the condition of 1300 DEG C, the material still has magnetism at 673K and excellent wave-absorbing performance, and has considerable industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of microwave absorbing materials technology, specifically relating to a simple method for in-situ synthesis of FeSi@SiC high-temperature resistant microwave absorbing materials. Background Technology

[0002] With the rapid development of military equipment, the competition between radar detection and stealth technology has become a focal point of air warfare. When aircraft exceed the speed of sound, ordinary stealth materials become unusable due to the increased temperature. Therefore, high-temperature absorbing materials have become crucial strategic materials. High-temperature absorbing materials can improve the performance and reliability of aircraft while protecting equipment from electromagnetic interference. In the field of electronic communications, high-temperature absorbing materials can be used to manufacture radomes, shielding covers, and other equipment. These devices effectively absorb electromagnetic waves, thereby reducing the impact of electromagnetic interference on communication equipment. Furthermore, high-temperature absorbing materials can also be used to manufacture high-temperature cables, which can operate in high-temperature environments without being affected by electromagnetic interference. In the aerospace field, high-temperature absorbing materials can be used to manufacture the outer shells of aircraft and rockets. These shells effectively absorb electromagnetic waves, thereby reducing the impact of natural disasters such as lightning strikes on aircraft and rockets.

[0003] Current high-temperature absorbing materials, while capable of withstanding high temperatures, cannot achieve the required absorption performance for their intended applications. Conversely, while meeting absorption performance requirements, they cannot withstand high temperatures, significantly limiting their application in high-temperature components. Therefore, researching high-temperature absorbing materials that combine high-temperature resistance and absorption capabilities is of significant practical importance and holds promising military application prospects. Summary of the Invention

[0004] The purpose of this invention is to provide a simple method for in-situ synthesis of FeSi@SiC high-temperature resistant microwave absorbing material, which combines high-temperature resistance and microwave absorption properties.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] A method for preparing FeSi@SiC high-temperature resistant microwave absorbing material by in-situ synthesis includes the following steps:

[0007] Step 1: Dissolve Fe(NO3)3·9H2O in anhydrous ethanol, then add SiC powder, impregnate and stir, evaporate the anhydrous ethanol in the solution, and then heat to remove the bound water in the solid.

[0008] Step 2: Grind the solid with the bound water removed into powder, add potassium chloride, mix well, and carry out reduction treatment;

[0009] Step 3: Grind the reduced solid powder thoroughly, add hydrochloric acid solution, filter, wash, and dry to obtain the FeSi@SiC material.

[0010] Preferably, in step 1, the molar ratio of the metallic element Fe to Si is 1.2:1.

[0011] Preferably, the heating temperature in step 1 is 400–600°C, and the heating time is 2–5 hours.

[0012] Preferably, in step 2, the molar ratio of the powder sample, Fe powder, and KCl is 3:8:12.

[0013] Preferably, in step 2, the reducing atmosphere is argon, the reducing temperature is 600–700°C, and the reducing time is 2–5 hours.

[0014] A FeSi@SiC high-temperature resistant microwave absorbing material prepared by the preparation method described above, wherein the material is formed by in-situ loading of FeSi onto SiC.

[0015] Applications of the FeSi@SiC high-temperature absorbing material as described above in radar detection, electronic communication, and aerospace fields.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] This invention employs a one-step in-situ synthesis of FeSi@SiC materials using an impregnation reduction method. The preparation method is simple, and the resulting FeSi@SiC materials possess both high-temperature resistance and microwave absorption properties. Their physical properties remain unchanged at 1300℃, and they still exhibit magnetism and excellent microwave absorption performance at 673K, demonstrating significant industrial application value. Attached Figure Description

[0018] Figure 1 The image shows the XRD pattern of the FeSi@SiC material prepared in Example 1.

[0019] Figure 2 The results show the electromagnetic wave absorption performance of the FeSi@SiC material prepared in Example 1.

[0020] Figure 3 The image shows the magnetization-temperature (MT) curve of the FeSi@SiC material prepared in Example 1.

[0021] Figure 4 The thermogravimetric (TGA) curve of the FeSi@SiC material prepared in Example 1 is shown. Detailed Implementation

[0022] To facilitate understanding of the present invention, a more comprehensive description will be provided below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0023] Example 1

[0024] (1) Based on the molar ratio of Fe to Si of the metal elements being 1.2:1, first weigh 1M of ferric nitrate nonahydrate Fe(NO3)3·9H2O and dissolve it in 20mL of anhydrous ethanol. Then add commercial SiC powder, impregnate and stir for 12h, and evaporate the anhydrous ethanol in the solution.

[0025] (2) The solid was placed in a muffle furnace and heated to 500°C at 5°C / min, and kept at 500°C for 2 hours to remove the bound water in the solid.

[0026] (3) Grind the solid with the bound water removed into a powder sample, and mix the sample with Fe powder (reduction) and KCl (heat absorption) in a molar ratio of 3:8:12. Place the mixed powder into a tube furnace and introduce argon gas. Keep it at 650℃ for 2 hours to allow the Fe2O3 in the mixed powder to partially reduce with SiC, and reduce FeSi in situ to be loaded onto SiC.

[0027] (4) The reduced powder solid was ground thoroughly and placed in 50 mL of 1 M hydrochloric acid solution and stirred for 5 h to remove impurities KCl, Fe salt and Fe powder. After filtration, washing and drying, FeSi@SiC material was obtained.

[0028] Structural characterization: The crystal microstructure of FeSi@SiC material was characterized by X-ray diffraction. The characterization results are shown in [reference needed]. Figure 1 The results showed that the material was a mixture of FeSi and SiC, proving that FeSi@SiC was successfully prepared in this embodiment.

[0029] Microwave absorption performance testing: The microwave absorption performance of FeSi@SiC material was tested using a vector network analyzer, with a test range of 2–18 GHz. The test results are shown in [link to test results]. Figure 2 The results show that the material has a minimum reflection loss of -54dB at a thickness of 2mm, and a reflection loss (RL) of -46dB at a thickness of 1.5mm. Currently, military products require a reflection loss of less than -5dB. According to these requirements, the 1.5mm thick sample exhibits a reflection loss of less than -5dB in the 10–18GHz range; while the 3.5mm thick sample shows a reflection loss of less than -2dB in the 3.5–18GHz range. Therefore, the FeSi@SiC material of this invention has high commercial development potential.

[0030] Magnetic property testing: The high-temperature magnetic properties of FeSi@SiC material were tested using a superconducting quantum interference magnetic measurement system (SQUID / MPMS). The test results are shown in [link to results]. Figure 3 The results show that the material still has a magnetic moment of 0.0012 emu at a high temperature of 673 K, which means that the material still has magnetic properties at a high temperature of 400℃, and the Curie temperature can reach 400℃.

[0031] Thermal stability testing: The thermal properties and thermal reactivity of the FeSi@SiC material were tested using thermogravimetric analysis. The test results are shown in [link to results]. Figure 4 The results showed that the material's mass did not change significantly at a high temperature of 1300℃, indicating that the material has excellent thermal stability.

[0032] The above description is only for better explaining the embodiments of the present invention and is not intended to limit them. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing FeSi@SiC high-temperature resistant microwave absorbing material by in-situ synthesis, characterized in that, Includes the following steps: Step 1: Dissolve Fe(NO3)3·9H2O in anhydrous ethanol, then add SiC powder, impregnate and stir, evaporate the anhydrous ethanol in the solution, and then heat to remove the bound water in the solid. In Step 1, the molar ratio of metal element Fe to Si is 1.2:

1. Step 2: Grind the solid after removing bound water into a powder sample, add Fe powder and KCl, mix evenly, and carry out reduction treatment at a temperature of 600~700℃; Step 3: Grind the reduced solid powder thoroughly, add hydrochloric acid solution, filter, wash, and dry to obtain FeSi@SiC high-temperature resistant microwave absorbing material.

2. The preparation method of the in-situ synthesized FeSi@SiC high-temperature resistant microwave absorbing material according to claim 1, characterized in that, In step 1, the heating temperature is 400~600℃ and the heating time is 2~5h.

3. The preparation method of the in-situ synthesized FeSi@SiC high-temperature resistant microwave absorbing material according to claim 1, characterized in that, In step 2, the molar ratio of the powder sample, Fe powder, and KCl is 3:8:

12.

4. The preparation method of the in-situ synthesized FeSi@SiC high-temperature resistant microwave absorbing material according to claim 1, characterized in that, In step 2, the reducing atmosphere is argon, and the reduction time is 2-5 hours.

5. A FeSi@SiC high-temperature resistant microwave absorbing material prepared by the preparation method according to any one of claims 1 to 4, characterized in that, The material is formed by in-situ loading of FeSi onto SiC.

6. The application of the FeSi@SiC high-temperature absorbing material according to claim 5 in radar detection, electronic communication and aerospace fields.

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