S-c band heat-resistant wave-absorbing material and preparation method thereof

Abstract

The application discloses an S-C wave band heat-resistant wave absorbing material and a preparation method, and relates to the technical field of S-C wave band wave absorbing materials. The S-C wave band heat-resistant wave absorbing material comprises ZrO2, Ta2O5 and TaC nanocrystals. The preparation method comprises the following steps: S1, preparing ZrTa MOF powder by using a hydrothermal method; S2, performing twice focal heat fast firing treatment on the ZrTa MOF powder to obtain a ZrTa / C composite material. The application takes ZrTa MOF as a precursor, performs twice focal heat fast firing on the ZrTa MOF under a power supply voltage of 26-30 V, rapidly prepares a nanoscale ZrTa / C composite wave absorbing material, and obtains a novel wave absorbing material containing ZrO2, Ta2O5 and TaC nanocrystals, which is high-temperature resistant and effectively wave absorbing. Further, the introduction of Ta in the application improves electromagnetic parameters of the wave absorbing material, so that S wave band wave absorption is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of S-C wave band wave absorbing materials, and particularly relates to an S-C wave band heat-resistant wave absorbing material and a preparation method. BACKGROUND

[0002] In modern communication and radar systems, the S band (2-4 GHz) and C band (4-8 GHz) are two crucial frequency bands, which are widely used in satellite communication, weather monitoring, aviation navigation, and military reconnaissance. Therefore, the demand for wave absorbing materials that can effectively absorb S-C band electromagnetic waves is increasing to counter reconnaissance.

[0003] Currently, although the wave absorbing materials on the market can meet the needs of specific frequency bands (such as the X band) to some extent, there are still significant challenges in the wave absorbing performance of the S band and C band, which limits their application in multi-band systems. At the same time, the wave absorbing performance of many wave absorbing materials in the S band and C band is not ideal, especially for the S band, which cannot achieve the expected absorption effect, which directly affects the performance of the system. Environmental factors such as temperature and humidity have a great influence on the performance of wave absorbing materials, leading to fluctuations in the performance of materials in actual use, making it difficult to maintain consistent wave absorbing effect. In addition, the preparation of high-performance wave absorbing materials often requires complex processes and expensive materials, which increases the production cost and limits its wide application.

[0004] Therefore, it is of great significance to develop a new type of wave absorbing material that can have excellent wave absorbing performance in the S band and C band, good thermal stability, simple preparation process, and controllable cost. SUMMARY

[0005] To solve the above technical problems, the application provides an S-C wave band heat-resistant wave absorbing material and a preparation method, which uses ZrTaMOF as a precursor, and rapidly prepares a nano-sized ZrTa / C composite wave absorbing material by twice fast firing ZrTa MOF under a power supply voltage of 26-30V, to obtain a new type of wave absorbing material containing ZrO2, Ta2O5 and TaC nanocrystals, which is high-temperature resistant and effectively wave absorbing. Further, the introduction of Ta in the application improves the electromagnetic parameters of the wave absorbing material to achieve S band wave absorption.

[0006] The first aspect of the application discloses a preparation method of an S-C wave band heat-resistant wave absorbing material, which comprises ZrO2, Ta2O5 and TaC nanocrystals.

[0007] The preparation method comprises the following steps:

[0008] Step S1, preparing ZrTa MOF powder by a hydrothermal method;

[0009] Step S2, the ZrTa MOF powder is subjected to twice of the focal heat quick firing treatment, to obtain a ZrTa / C composite material.

[0010] The power supply voltage of the focal heat quick firing is 26-30V, the time of each focal heat quick firing is 1-2s, and the interval time between the two focal heat quick firings is 11-12s.

[0011] According to the preparation method of the S-C wave band heat-resistant wave-absorbing material, the step S1 comprises the following sub-steps:

[0012] Step S11, a certain amount of ZrCl4, TaCl4 and terephthalic acid are dissolved in a certain volume of N,N-dimethylformamide to prepare a precursor solution, and then the precursor solution is transferred to a reaction kettle, and the reaction kettle is placed in an oven at 145-155℃ for 8-10h, after the reaction is completed, the reaction kettle is taken out and naturally cooled at room temperature to obtain a solid product;

[0013] Step S12, the solid product is subjected to centrifugation and washing, and finally the washed solid product is dried to obtain a ZrTa MOF powder.

[0014] According to the preparation method of the S-C wave band heat-resistant wave-absorbing material, in the step S11, the mass concentration of ZrCl4 is 20-27mg / mL, and the mass ratio of ZrCl4, TaCl4 and terephthalic acid is (3-4):(2-4):(4-6).

[0015] According to the preparation method of the S-C wave band heat-resistant wave-absorbing material, in the step S12, the solid product is first washed with N,N-dimethylformamide, and then washed with ethanol.

[0016] According to the preparation method of the S-C wave band heat-resistant wave-absorbing material, in the step S12, the washed solid product is dried in an oven at room temperature or 60-80℃.

[0017] According to the preparation method of the S-C wave band heat-resistant wave-absorbing material, in the step S2, the power supply voltage of the focal heat quick firing is 27-29V.

[0018] According to the preparation method of the S-C wave band heat-resistant wave-absorbing material, in the step S2, the treatment process of the focal heat quick firing is as follows:

[0019] The direct current power supply is used as the power supply, two wires are led out from the positive and negative poles of the direct current power supply, and are connected with two pieces of carbon cloth aligned up and down to form a loop, then the ZrTa MOF powder is placed between the two pieces of carbon cloth, and the ZrTa MOF powder is subjected to a fast heat treatment in an inert gas atmosphere.

[0020] According to the preparation method of the S-C wave band heat-resistant wave-absorbing material, the inert gas is argon or nitrogen.

[0021] The second aspect of the application discloses an S-C wave band heat-resistant wave-absorbing material prepared by the preparation method of the S-C wave band heat-resistant wave-absorbing material.

[0022] According to the S-C wave band heat-resistant wave-absorbing material, the sizes of the ZrO2, Ta2O5 and TaC nanocrystals are all 20-50 nm.

[0023] According to the S-C wave band heat-resistant wave-absorbing material, the mass loss of the S-C wave band heat-resistant wave-absorbing material is not more than 20% during the temperature rising process in an air atmosphere at 200-1200 DEG C.

[0024] The scheme provided by the application has the following technical effects:

[0025] The application uses ZrTa MOF as a precursor, and quickly prepares nanoscale ZrTa / C composite wave-absorbing material by twice fast heat treatment of ZrTa MOF under a power supply voltage of 26-30 V, obtains a new wave-absorbing material containing ZrO2, Ta2O5 and TaC nanocrystals, which is high-temperature resistant and effective in wave absorption, the introduction of Ta can effectively control the electromagnetic parameters of the ZrTa / C composite material in the S wave band, and improve the impedance matching ability of the composite material in the S wave band, so that as many S wave band electromagnetic waves as possible incident on the surface of the material enter the material interior, instead of being reflected, thereby improving the wave absorption ability of the material in the S wave band.

[0026] In addition, the prepared heat-resistant ZrTa / C composite wave-absorbing material has a reflection loss of-15.04 dB at an S wave band frequency of 4 GHz.

[0027] In addition, the prepared heat-resistant ZrTa / C composite wave-absorbing material has a mass loss of not more than 20% during the temperature rising process in an air atmosphere at 200-1200 DEG C, and has excellent high-temperature stability. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the accompanying drawings needed to be used in the description of the specific embodiments or the prior art will be briefly introduced. Obviously, the accompanying drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0029] Figure 1 Preparation method flow chart of an S-C wave band heat-resistant wave-absorbing material according to an embodiment of the present application;

[0030] Figure 2 Scanning electron microscope photos of ZrTa MOF amplified by 10,000 times (a) and 30,000 times (b);

[0031] Figure 3 XRD chart of ZrTa MOF;

[0032] Figure 4 Transmission electron microscope photos of ZrTa / C composite material prepared in Example 1 of the present application under 200 nm (a), 100 nm (b), 50 nm (c) scales;

[0033] Figure 5 Transmission electron microscope photos of ZrTa / C composite material prepared in Comparative Example 1 under 200 nm (a), 100 nm (b), 50 nm (c) scales;

[0034] Figure 6 Transmission electron microscope photos of ZrTa / C composite material prepared in Comparative Example 2 under 200 nm (a), 100 nm (b), 20 nm (c) scales;

[0035] Figure 7 XRD charts of ZrTa / C composite material prepared in Comparative Example 2 (a), Comparative Example 1 (b) and Example 1 (c) of the present application;

[0036] Figure 8 Raman spectrum of ZrTa / C composite material prepared in Comparative Example 1 (a) and Example 1 (b) of the present application;

[0037] Figure 9 Thermogravimetric curve obtained by testing ZrTa / C composite material prepared in Example 1 of the present application in air environment;

[0038] Figure 10 Reflection loss chart of ZrTa / C composite material prepared in Example 1 (a), Comparative Example 1 (b) and Comparative Example 2 (c) of the present application. DETAILED DESCRIPTION

[0039] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0040] The first aspect of the present embodiment discloses a preparation method of S-C band heat-resistant wave-absorbing material, wherein the S-C band heat-resistant wave-absorbing material comprises ZrO2, Ta2O5 and TaC nanocrystals.

[0041] As shown in Figure 1 The preparation method comprises the following steps:

[0042] In step S1, ZrTa MOF powder is prepared by a hydrothermal method.

[0043] In step S2, the ZrTa MOF powder is subjected to twice of fast calcination treatment to obtain ZrTa / C composite material.

[0044] Compared with the ZrO2 / C composite material obtained by fast calcination treatment of single metal Zr MOF, the present application introduces Ta element, first obtains bimetallic ZrTa MOF, and then subjects the bimetallic ZrTa MOF to fast calcination treatment to obtain ZrTa / C composite wave-absorbing material containing ZrO2, Ta2O5 and TaC three kinds of nanocrystals. The introduction of Ta can effectively improve the electromagnetic parameters of ZrTa / C composite material in the S band, and improve the impedance matching ability of the composite material in the S band, so that as many S band electromagnetic waves as possible incident on the surface of the material enter the material interior, and are not reflected, thereby improving the wave-absorbing ability of the material in the S band.

[0045] In step S1, ZrTa MOF powder is prepared by a hydrothermal method.

[0046] In some embodiments, the step S1 comprises the following sub-steps:

[0047] In step S11, a certain amount of ZrCl4, TaCl4 and terephthalic acid is dissolved in a certain volume of N,N-dimethylformamide to prepare a precursor solution, and then the precursor solution is transferred to a reaction kettle, and the reaction kettle is placed in an oven at 145-155 DEG C for 8-10 h. After the reaction is completed, the reaction kettle is taken out and naturally cooled at room temperature to obtain a solid product.

[0048] Specifically, the reaction temperature of the reaction kettle in the oven can be 145℃, 150℃, 155℃. Preferably, the reaction temperature of the reaction kettle in the oven is 150℃.

[0049] Specifically, the reaction time of the reaction kettle in the oven can be 8h, 9h, 10h. Preferably, the reaction time of the reaction kettle in the oven is 9h.

[0050] In step S12, the solid product is centrifuged, washed, and finally dried to obtain a ZrTa MOF powder.

[0051] In some embodiments, in the step S11, the mass concentration of ZrCl4 is 20-27mg / mL, and the mass ratio of ZrCl4, TaCl4 and terephthalic acid is (3-4):(2-4):(4-6).

[0052] Specifically, the mass concentration of ZrCl4 can be 20mg / mL, 21mg / mL, 22mg / mL, 23mg / mL, 24mg / mL, 25mg / mL, 26mg / mL, 27mg / mL. Preferably, the mass concentration of ZrCl4 is 23-25mg / mL.

[0053] In some embodiments, in the step S12, the solid product is first washed with N,N-dimethylformamide, and then washed with ethanol to remove residual organic matter.

[0054] In some embodiments, in the step S12, the washed solid product is dried at room temperature or in an oven at 60-80℃.

[0055] In step S2, the ZrTa MOF powder is subjected to twice of the fast pyrolysis treatment to obtain a ZrTa / C composite material.

[0056] In some embodiments, in the step S2, the fast pyrolysis treatment process is as follows:

[0057] A direct current power supply is used as an energy supply power source, two wires are drawn from the positive and negative electrodes of the direct current power supply, and are connected with two pieces of carbon cloth aligned above and below to form a loop. Then the ZrTa MOF powder is placed between the two pieces of carbon cloth, and the ZrTa MOF powder is subjected to fast pyrolysis treatment in an inert gas atmosphere.

[0058] In some embodiments, the inert gas is argon or nitrogen.

[0059] Preferably, the carbon cloth is placed in a glassware, Ar is introduced into the glassware to exclude air, and an Ar atmosphere is provided.

[0060] In some embodiments, the power supply voltage for the focal heat fast burning is 26-30V, the time for each focal heat fast burning is 1-2s, and the interval time between two focal heat fast burnings is 11-12s.

[0061] When the power supply voltage for the focal heat fast burning is less than 26V, the ZrTa MOF framework has the phenomenon of incomplete collapse, and part of Zr and Ta act as catalysts to catalyze the decomposition of terephthalic acid to generate carbon nanotubes. In addition, the power supply voltage is too small, and the ZrTa MOF organic framework cannot be completely decomposed into carbon, so the material has weak conductivity loss ability. When the power supply voltage for the focal heat fast burning is greater than 30V, the ZrTa MOF organic framework gasifies and volatilizes at high temperature, and the target product ZrTa / C composite material cannot be obtained.

[0062] Meanwhile, the ZrTa MOF framework is subjected to two focal heat fast burnings in the present application, so that the MOF framework can completely collapse to generate ZrO2, Ta2O5 and TaC nanocrystals. However, in order to avoid the agglomeration of ZrO2, Ta2O5 and TaC nanocrystals at a continuous high temperature, the interval time between two focal heat fast burnings is 11-12s, so that the ZrO2, Ta2O5 and TaC nanocrystals formed at a high temperature have not had time to continue to agglomerate before the reaction process is cooled down, that is, the uniform loading of ZrO2, Ta2O5 and TaC nanocrystals with a size of 20-50nm on the thin-layer carbon can be realized.

[0063] Specifically, the power supply voltage for the focal heat fast burning can be 26V, 27V, 28V, 29V and 30V. Preferably, the power supply voltage for the focal heat fast burning is 27-29V. Further preferably, the power supply voltage for the focal heat fast burning is 28V.

[0064] Specifically, the time for each focal heat fast burning can be 1s, 1.5s, 2s. Preferably, the time for each focal heat fast burning is 2s.

[0065] Specifically, the interval time between two focal heat fast burnings can be 11s, 11.5s, 12s.

[0066] The second aspect of the present embodiment discloses an S-C band heat-resistant wave-absorbing material prepared by the preparation method of the aforementioned S-C band heat-resistant wave-absorbing material, and the S-C band heat-resistant wave-absorbing material comprises ZrO2, Ta2O5 and TaC nanocrystals.

[0067] In some embodiments, the size of the ZrO2, Ta2O5 and TaC nanocrystals is 20-50nm.

[0068] In some embodiments, the S-C waveband heat-resistant wave-absorbing material has a mass loss of no more than 20% during a temperature rise from 200 to 1200°C in an air atmosphere.

[0069] Example 1

[0070] (1) 0.3-0.4g ZrCl4, 0.2-0.4g TaCl4 and 0.4-0.6g terephthalic acid were sequentially added to 15ml N,N-dimethylformamide and uniformly stirred by ultrasonic agitation to obtain a precursor solution, which was then transferred to a reaction kettle, and the reaction kettle was placed in an oven at 145-155°C for 8-10h. After the reaction was completed, the reaction kettle was removed and allowed to cool naturally at room temperature to obtain a solid product;

[0071] (2) The solid product was subjected to multiple centrifugation and washing with N,N-dimethylformamide and / or ethanol using a centrifuge, and finally the washed solid product was dried at room temperature or in an oven at 60-80°C to obtain a ZrTa MOF powder.

[0072] (3) A direct current power supply was used as the power supply, two wires were drawn from the positive and negative electrodes of the direct current power supply and connected to two pieces of carbon cloth aligned above and below to form a loop, and then the ZrTa MOF powder was placed between the two pieces of carbon cloth, and the ZrTa MOF powder was subjected to two times of rapid heat treatment in an argon atmosphere to obtain a ZrTa / C composite material as an S-C waveband heat-resistant wave-absorbing material.

[0073] The power supply voltage for the rapid heat treatment was 28V, the time for each rapid heat treatment was 2s, and the interval time between the two rapid heat treatments was 11s.

[0074] Comparative Example 1

[0075] The difference from Example 1 is that the power supply voltage for the rapid heat treatment was 22V.

[0076] Comparative Example 2

[0077] The difference from Example 1 is that the power supply voltage for the rapid heat treatment was 16V.

[0078] Figure 2 Scanning electron microscope photographs of ZrTa MOF magnified by 10,000 times (a) and 30,000 times (b). It can be seen from the photographs that the ZrTa MOF has a regular polyhedral shape, and the particle size is about 200-500nm. Figure 2 It can be seen that the ZrTa MOF has a regular polyhedral shape, and the particle size is about 200-500nm.

[0079] Figure 3The XRD pattern of ZrTa MOF, the peaks at 22.31°, 25.78°, 30.77° in the pattern belong to (115), (224), (046) crystal face, which corresponds to the typical characteristic peaks of Zr-based MOF material, confirming the successful preparation of ZrTa MOF.

[0080] Figure 4 The transmission electron microscope photos of ZrTa / C composite material prepared according to Example 1 in the application at 200 nm (a), 100 nm (b), 50 nm (c) scales. From Figure 4 It can be seen that the particle size of nanocrystals in the ZrTa / C composite material obtained in Example 1 is 20-50 nm, and is uniformly loaded on the carbon substrate.

[0081] Figure 5 The transmission electron microscope photos of ZrTa / C composite material prepared according to Comparative Example 1 at 200 nm (a), 100 nm (b), 50 nm (c) scales. From Figure 5 It can be seen that the particle size of nanocrystals in the ZrTa / C composite material obtained in Comparative Example 1 is 10-20 nm, and the particle size of nanocrystals is reduced compared with Example 1. This is because the power supply voltage of Comparative Example 1 is 22V, which is lower than the power supply voltage of 28V in Example 1, so the upper limit of high temperature is reduced compared with Example 1, and thus the supercooling degree is also reduced, which will lead to low nucleation rate of Zr and Ta in the material, and Zr and Ta are not easy to coarsen and grow, so the particle size of nanocrystals in the composite material is smaller than that in Example 1.

[0082] Figure 6 The transmission electron microscope photos of ZrTa / C composite material prepared according to Comparative Example 2 at 200 nm (a), 100 nm (b), 20 nm (c) scales. From Figure 6 It can be seen that the microstructure of the ZrTa / C sample prepared in Comparative Example 2 still retains a certain microstructure of ZrTa MOF, and is not completely decomposed. And the microstructure of the ZrTa / C composite material prepared in Comparative Example 2 produces slender carbon nanotubes, which indicates that in the pyrolysis fast firing process at a voltage of 16V, Zr and Ta act as catalysts to catalyze the decomposition of terephthalic acid, producing a lot of carbon nanotubes, and at the same time, the size of ZrTa nanocrystals in the ZrTa / C prepared by pyrolysis fast firing at a voltage of 16V is smaller, which is 2-5 nm.

[0083] Figure 7 The XRD patterns of ZrTa / C composite material prepared according to Comparative Example 2 (a), Comparative Example 1 (b) and Example 1 (c) in the application. From Figure 7It can be seen that the 16V voltage pyrolysis ZrTa MOF, the sample is not completely decomposed at low temperature, still maintains the characteristic diffraction peaks similar to ZrTa MOF, which shows that ZrTa MOF has good thermal stability. However, the XRD of the final product of the 22V and 28V voltage pyrolysis ZrTa MOF has changed significantly. Among them, the XRD pattern of the sample pyrolyzed at 22V voltage appears peaks at 22.962°, 28.493°, 36.867°, 50.403°, corresponding to Ta2O5(PDF 18-1304), and peaks at 29.721° and 56.662°, corresponding to Ta2O5(PDF 54-0514), proving that Ta in the ZrTa / C composite obtained at 22V voltage exists in the form of Ta2O5 and Zr exists in the form of ions, because Zr needs a higher temperature to be oxidized to ZrO2, which also reflects the high temperature stability of Zr, and under the condition of low voltage, the upper limit of high temperature is insufficient, so Zr cannot be reacted to ZrO2. The XRD pattern of the sample pyrolyzed at 28V voltage appears peaks at 30.119°, 50.219° and 62.678°, corresponding to ZrO2(PDF 49-1642); peaks at 22.692°, 28.493°, 36.867°, corresponding to Ta2O5(PDF 18-1304); peaks at 34.85°, 40.46°, 58.55° and 70.0°, corresponding to TaC(PDF 35-0801). It is proved that the ZrTa / C composite obtained at 28V voltage contains ZrO2, Ta2O5 and TaC nanocrystals at the same time.

[0084] Figure 8 The Raman spectrum of the ZrTa / C composite prepared in Example 1(b) according to the application is shown in Figure 1, and the Raman spectrum of Comparative Example 1(a) is shown in Figure 2. The peaks at 1350 cm -1 and 1590 cm -1 correspond to the D peak and G peak of carbon, and their intensities are represented by I D and I G . The 1350 cm -1 peak is attributed to disordered carbon, which is related to disordered sp 3 hybrid carbon; the 1590 cm -1 peak is related to ordered sp 2 hybrid graphite carbon. The ratio of I D and I G is used to characterize the structural defects and disorder degree of the material, and from Figure 8It can be seen that the peak ratio of the ZrTa / C sample obtained by the 22V voltage pyrolysis fast burning ZrTa MOF is 0.911, and the peak ratio of the ZrTa / C sample obtained by the 28V voltage pyrolysis fast burning ZrTa MOF is 0.929. That is, as the pyrolysis fast burning voltage increases, the peak ratio becomes larger, indicating that the defect structure of the ZrTa / C composite material obtained by the embodiment 1 of the application is improved, and the polarization loss ability is strengthened compared with the comparative example 1.

[0085] Figure 9 The obtained thermogravimetric curve of the ZrTa / C composite material prepared according to the embodiment 1 of the application is tested in an air environment. From Figure 9 It can be seen that the ZrTa / C composite material has a slight weight loss before 400℃, which is caused by the evaporation of the adsorbed water molecules in the ZrTa / C composite material; the ZrTa / C composite material has a mass loss of not more than 20% between 400-700℃, which is caused by the further reaction of carbon at high temperature; and the ZrTa / C composite material no longer has a mass loss after 700℃. However, compared with the current research, the ZrTa / C obtained by the 28V heat treatment still exhibits excellent thermal stability, because most of the MOFs diffraction wave-absorbing materials in the current research are tested in an inert gas atmosphere, and the mass loss is up to 40%; while the thermal stability of the ZrTa / C composite material of the application is tested in an air atmosphere, and the loss is still not higher than 20% when heated to 1200℃, which proves the excellent high-temperature stability of the ZrTa / C sample.

[0086] Figure 10 The reflection loss diagram of the ZrTa / C composite material prepared according to the embodiment 1 (a) of the application, the comparative example 1 (b) and the comparative example 2 (c) is shown. Wherein, the reflection loss lower than -10dB represents that the sample can realize 90% absorption of the electromagnetic wave in the frequency band. From Figure 10It can be seen that the ZrTa / C composite material of the embodiment 1 of the present application has a maximum reflection loss of -15.04 dB at a thickness of 3.6 mm and a frequency of 4 GHz. At a thickness of 3.4 mm, the frequency range with a reflection loss of -10 dB is 3.84-5.08 GHz, and the effective bandwidth is 1.2 GHz. Overall, the working waveband of the ZrTa / C composite material of the embodiment 1 of the present application is 3.53-5.4 GHz and 15.7-17 GHz, which is the S-C waveband and the Ku waveband. The maximum reflection loss value in the S waveband is -15 dB, which has application prospects. The sample of the comparative example 1 has a maximum reflection loss of -27.7 dB at a thickness of 3.4 mm and a frequency of 5.73 GHz. At a thickness of 2.8 mm, the frequency range with a reflection loss of -10 dB is 5.65-7.7 GHz, and the effective bandwidth is 2 GHz. Overall, the working waveband of the sample of the comparative example 1 is 4.4-8.2 GHz, which is the C waveband. The sample of the comparative example 2 has a maximum reflection loss of -24.2 dB at a thickness of 2.2 mm and a frequency of 16.64 GHz. At a thickness of 2.2 mm, the frequency range with a reflection loss of -10 dB is 15-18 GHz, and the effective bandwidth is 3 GHz. Overall, the working waveband of the sample of the comparative example 2 is 13-18 GHz, which is the Ku waveband.

[0087] Embodiment 2

[0088] The difference from the embodiment 1 is that the power supply voltage of the focal heat quick burning is 26 V.

[0089] Embodiment 3

[0090] The difference from the embodiment 1 is that the power supply voltage of the focal heat quick burning is 27 V.

[0091] Embodiment 4

[0092] The difference from the embodiment 1 is that the power supply voltage of the focal heat quick burning is 29 V.

[0093] Embodiment 5

[0094] The difference from the embodiment 1 is that the power supply voltage of the focal heat quick burning is 30 V.

[0095] Embodiment 6

[0096] The difference from the embodiment 1 is that the time of each focal heat quick burning is 1 s, and the interval time between two times of focal heat quick burnings is 12 s.

[0097] Embodiment 7

[0098] The difference from example 1 is that the time of each focal heat fast burning is 1.5s, and the interval time between two focal heat fast burnings is 11.5s.

[0099] In summary, the scheme provided in the application has the following technical effects:

[0100] The application uses ZrTa MOF as a precursor, and through twice focal heat fast burning of ZrTa MOF under a power supply voltage of 26-30V, a nanoscale ZrTa / C composite wave-absorbing material is quickly prepared, a new wave-absorbing material containing ZrO2, Ta2O5 and TaC nanocrystals is obtained, and the material is high-temperature-resistant and effective in wave absorption. The introduction of Ta can effectively regulate the electromagnetic parameters of the ZrTa / C composite material in the S wave band, and improve the impedance matching ability of the composite material in the S wave band, so that as many S wave band electromagnetic waves as possible incident on the surface of the material enter the material interior, instead of being reflected, thereby improving the wave-absorbing ability of the material in the S wave band.

[0101] In addition, the heat-resistant ZrTa / C composite wave-absorbing material prepared by the application has a reflection loss of-15.04dB at a frequency of 4GHz in the S wave band.

[0102] In addition, the heat-resistant ZrTa / C composite wave-absorbing material prepared by the application has a mass loss of not more than 20% during the temperature rising process from 200℃ to 1200℃ in an air atmosphere, and has excellent high-temperature stability.

[0103] Note that the technical features of the above examples can be combined in any way, and in order to make the description concise, all possible combinations of the technical features in the above examples are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the description. The above examples only express several embodiments of the application, and the description is more specific and detailed, but it should not be interpreted as a limitation on the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the application, a number of modifications and improvements can be made, which are within the scope of the application. Therefore, the scope of the patent of the application should be subject to the appended claims.

Claims

1. A preparation method of an S-C band heat-resistant wave-absorbing material, characterized in that, The S-C wave band heat-resistant wave-absorbing material comprises ZrO2, Ta2O5 and TaC nanocrystals. The preparation method comprises the following steps: S1, preparing ZrTa MOF powder by a hydrothermal method; The step S1 comprises the following sub-steps: S11, weighing a certain amount of ZrCl4, TaCl4 and terephthalic acid, dissolving them in a certain volume of N,N-dimethylformamide to prepare a precursor solution, then transferring the precursor solution to a reaction kettle, and then placing the reaction kettle in an oven at 145-155 DEG C for 8-10 h, after the reaction is completed, taking out the reaction kettle and naturally cooling it at room temperature to obtain a solid product; In the step S11, the mass concentration of ZrCl4 is 20-27 mg / mL, and the mass ratio of ZrCl4, TaCl4 and terephthalic acid is (3-4):(2-4):(4-6); S12, centrifuging and washing the solid product, and finally drying the washed solid product to obtain ZrTa MOF powder; S2, performing two times of fast pyrolysis treatment on the ZrTa MOF powder to obtain an S-C wave band heat-resistant wave-absorbing material; The power supply voltage of the fast pyrolysis is 26-30 V, the time of each fast pyrolysis is 1-2 s, and the interval time between the two fast pyrolyses is 11-12 s. 2.The preparation method of the S-C band heat-resistant wave-absorbing material according to claim 1, characterized in that, In the step S12, the solid product is first washed with N,N-dimethylformamide, and then washed with ethanol. 3.The preparation method of the S-C band heat-resistant wave-absorbing material according to claim 1, characterized in that, In the step S12, the washed solid product is dried at room temperature or in an oven at 60-80 DEG C. 4.The preparation method of the S-C band heat-resistant wave-absorbing material according to claim 1, characterized in that, In the step S2, the power supply voltage of the fast pyrolysis is 27-29 V. 5.The preparation method of the S-C band heat-resistant wave-absorbing material according to claim 1, characterized in that, In the step S2, the fast pyrolysis treatment process is as follows: A direct current power supply is used as the energy supply source, two wires are drawn from the positive and negative electrodes of the direct current power supply and connected with two pieces of carbon cloth in alignment to form a loop, then the ZrTa MOF powder is placed between the two pieces of carbon cloth, and the ZrTa MOF powder is subjected to fast pyrolysis treatment in an inert gas atmosphere. 6.The preparation method of the S-C wave band heat-resistant wave absorbing material according to claim 5, characterized in that, The inert gas is argon or nitrogen.

7. The S-C wave band heat-resistant wave absorbing material prepared by the method according to any one of claims 1-6, characterized in that, The size of the ZrO2, Ta2O5 and TaC nanocrystals is 20-50 nm.

8. The S-C band heat-resistant wave-absorbing material according to claim 7, characterized in that, The mass loss of the S-C wave band heat-resistant wave-absorbing material during the temperature rising process at 200-1200 DEG C in air atmosphere is not more than 20%.

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