Polymer cracked multi-element silicon-based ceramic wave-absorbing coating and preparation method thereof

Abstract

The invention discloses a polymer cracked multi-element silicon-based ceramic wave-absorbing coating and a preparation method thereof, and belongs to the technical field of design and preparation of wave-absorbing coatings. A preparation method of a polymer cracked multi-element silicon-based ceramic wave-absorbing coating comprises the following steps: dissolving organosilane in an organic solvent in a protective atmosphere to obtain a first solution; adding a wave-absorbing modified component into the first solution to obtain a second solution; and coating a second solution on a base material in a protective atmosphere, curing at 120-300 DEG C, and then cracking at 900-1100 DEG C to obtain the polymer cracked multi-element silicon-based ceramic wave-absorbing coating. The polymer cracked multi-element silicon-based ceramic wave-absorbing coating prepared by the preparation method disclosed by the invention has excellent wave-absorbing performance and good high-temperature adhesive force with a matrix.

Description

Technical Field

[0001] The present invention relates to the technical field of design and preparation of radar-absorbing coatings, and more specifically to a polymer pyrolysis multi-component silicon-based ceramic radar-absorbing coating and a preparation method thereof. Background Art

[0002] With the increasingly important role of radar-absorbing materials in the stealth defense system of military equipment, especially for special components such as engine tail nozzles and cruise missile warheads serving in high-temperature extreme environments, the research and development of high-temperature resistant stealth materials with high-efficiency wave absorption have important scientific significance and military application prospects. Radar wave absorbing materials can be divided into two categories according to the forming process: coating-type wave absorbing materials and structural wave absorbing materials. Compared with structural wave absorbing materials, coating-type wave absorbing materials introduce absorbents with excellent wave absorption performance into the coating material and are coated on the target object by a coating process to achieve the purpose of absorbing radar waves and realizing radar stealth. Coating-type wave absorbing materials have the advantages of simple preparation and forming processes, low cost, and high absorption efficiency, and are widely used in the field of electromagnetic wave absorbing materials.

[0003] Focusing on the field of high-temperature wave absorption, currently, high-temperature wave-absorbing coatings are mainly composed of a binder carrier and high-temperature wave-absorbing agents dispersed in the carrier. Commonly used high-temperature wave-absorbing agents include carbon materials, SiC materials, ternary layered compounds, and metal oxides, etc. They are the main components for the wave-absorbing coating materials to play their roles in high-temperature extreme environments. In order to match the impedance of free space, these conductor or semiconductor wave-absorbing agents need to be compounded with a low-dielectric and low-loss wave-transmitting carrier. As the wave-transmitting carrier of the high-temperature wave-absorbing coating, it not only needs to play the role of bonding the substrate, but also needs to have low density, good high-temperature thermal stability, and antioxidant properties. Organic carriers such as epoxy resin and silicone resin have very low heat-resistant temperatures (<400 °C) and are difficult to use under high-temperature conditions; inorganic glass has relatively high heat resistance, but the use temperature is limited to below the glass softening point; inorganic ceramic carriers represented by Al2O3 and Si3N4 have more advantages in terms of high temperature resistance and high strength, etc., but the coating preparation process has high requirements and it is difficult to match with the substrate material, and an additional transition layer or binder is required. In contrast, the polymer pyrolysis ceramic technology is a method for low-temperature preparation of inorganic ceramic materials by designing the molecular composition of organic precursors. Since its birth more than 50 years ago, this technology has developed rapidly and has been widely used in the preparation of fibers, coatings, bulk materials, and ceramic matrix composites, etc. The multi-component silicon-based ceramics obtained by this method not only have excellent properties such as light weight, high temperature resistance, oxidation resistance, and controllable composition, but also have semiconductor properties similar to SiC, and the dielectric properties can be adjusted, showing great application potential in the field of high-temperature electromagnetic absorption.

[0004] However, when using polymer pyrolysis multi - silicon - based ceramics (such as SiZrCN, SiBCN, and SiZrBCN, etc.) to prepare high - temperature resistant microwave absorbing materials currently, there are mainly two problems: (1) Although polymer pyrolysis multi - silicon - based ceramics (such as SiZrCN, SiBCN, and SiZrBCN, etc.) have certain microwave absorbing properties and certain potential for high - temperature microwave absorption, the overall microwave absorbing performance of pure ceramic materials is poor and cannot meet the requirements of practical applications. Although relevant research has used the method of doping elements for modification, the effect is not obvious; (2) The methods for preparing high - temperature resistant microwave absorbing materials using polymer pyrolysis multi - silicon - based ceramics (such as SiZrCN, SiBCN, and SiZrBCN, etc.) mainly focus on the construction and shaping of composite ceramics. For example, introducing metal absorbers containing magnetic components, conductive fillers, etc. into silicon - based precursors, or filling liquid precursors in fiber preforms or porous ceramics to achieve microwave absorption effects. However, the applicability of such process methods is limited and only applicable to porous substrates. It is difficult to effectively coat the coating on substrates with a smooth surface. Especially in a high - temperature application environment, general adhesives cannot withstand high service temperatures, which will cause the high - temperature resistant ceramic microwave absorbing coating to peel off from the substrate. Therefore, aiming at the problems of poor microwave absorbing performance of polymer pyrolysis multi - silicon - based ceramics themselves and poor high - temperature adhesion between the microwave absorbing coating prepared by traditional coating processes and the substrate, new solutions are urgently needed. While improving the microwave absorbing performance of polymer pyrolysis multi - silicon - based ceramics, the high - temperature adhesion between the coating and the substrate is improved, providing guidance for the application of high - temperature resistant microwave absorbing ceramics in the stealth field. Summary of the Invention

[0005] In view of the above problems, the present invention provides a polymer pyrolysis multi - silicon - based ceramic microwave absorbing coating and a preparation method thereof. The polymer pyrolysis multi - silicon - based ceramic microwave absorbing coating prepared by the present invention has excellent microwave absorbing performance and good high - temperature adhesion to the substrate.

[0006] The present invention has two objectives. The first objective is to provide a preparation method for a polymer pyrolysis multi - silicon - based ceramic microwave absorbing coating, and the second objective is to provide a modification method for the microwave absorbing performance of a polymer pyrolysis multi - silicon - based ceramic microwave absorbing coating, including the following steps: Under a protective atmosphere, dissolve organosilane in an organic solvent to obtain a first solution.

[0007] Add a microwave absorbing modification component to the first solution to obtain a second solution.

[0008] Under a protective atmosphere, coat the second solution on the substrate material, cure it at 120°C - 300°C, and then pyrolyze it at 900°C - 1100°C to obtain a polymer pyrolysis multi - silicon - based ceramic microwave absorbing coating.

[0009] In the coating step, the number of coating times is determined according to actual requirements.

[0010] In a preferred embodiment of the present invention, the addition amount of the wave-absorbing modification component is 1% - 3% of the mass of the second solution.

[0011] In a preferred embodiment of the present invention, it further includes that after pyrolysis, calcination is carried out at 1300 °C - 1600 °C under a protective atmosphere.

[0012] In a preferred embodiment of the present invention, the calcination time is 2 h - 5 h.

[0013] In a preferred embodiment of the present invention, the curing time is 60 min - 180 min.

[0014] In a preferred embodiment of the present invention, the pyrolysis time is 60 min - 120 min.

[0015] In a preferred embodiment of the present invention, the mass ratio of the organosilane to the organic solution is 1:4 - 6. The organosilane is selected from polycarbosilane, polysilazane, polysiloxane or polyborosilazane. The organic solvent is anhydrous toluene, xylene, n - hexane, acetone, etc.

[0016] In a preferred embodiment of the present invention, it further includes: adding an organic complex to the first solution.

[0017] The central element of the organic complex is one or two of Zr, Hf, Ti, V, Ta, Al and B. When the central element is zirconium, the organic complex can be zirconium oxychloride, zirconium tetrachloride, zirconium acetylacetonate, tetrabutyl zirconate, tetra - diethylamino zirconium, tetra - dimethylamino zirconium, tetra - dichloroferrocene zirconium, etc. When the central element is boron, the organic complex can be a boron hydride reagent, such as boric acid, boron trichloride, borane dimethyl sulfide, borazine, etc.

[0018] In a preferred embodiment of the present invention, it further includes: adding a wave - absorbing modification component to the first solution; The wave - absorbing modification component is a carbon material, SiC, a ternary layered compound, a metal oxide or a carbide. The carbon material is such as carbon black, carbon nanotubes, carbon nanowires, carbon fibers, graphene, etc. The ternary layered compound is a MAX phase, such as Ti3SiC2, Ti3AlC2, etc. The metal oxide is such as ZnO, TiO2, SnO2, etc. The carbide is such as TiC. In a preferred embodiment of the present invention, the matrix material can be a metal alloy, single - crystal silicon, SiC, C / C composite material, C / SiC composite material, etc.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention directly coats the modified precursor liquid on the substrate and uses the polymer pyrolysis technology to prepare the multi-component silicon-based ceramic microwave absorption coating. The addition of microwave absorption modification components can effectively improve the microwave absorption performance of the material. Compared with other ceramics, the polymer pyrolysis amorphous multi-component silicon-based ceramic is a new type of inorganic high-temperature microwave absorption coating carrier with good compatibility with the matrix material. It can achieve strong adhesion with the matrix without adding additional binders and has a wide range of applications, meeting the application requirements of various microwave absorption scenarios.

[0020] (2) For the coatings that need further treatment, through high-temperature calcination, a microstructure with uniformly dispersed in-situ precipitated nano microwave absorption agent particles in the amorphous carrier can be obtained, thereby realizing the regulation of the dielectric properties and electromagnetic microwave absorption properties of the coating.

[0021] (3) Compared with the unmodified silicon-based ceramic, the multi-component silicon-based ceramic with added organic complexing agent and adjusted elements exhibits excellent thermal stability and antioxidant ability, and has important application value in the field of high-temperature microwave absorption.

[0022] (4) The liquid polymer precursor can accommodate different types of microwave absorption modification components and can prepare high-temperature resistant microwave absorption coatings of various systems at relatively low temperatures. Compared with the preparation methods of ordinary ceramics, it has obvious cost advantages, and the microwave absorption performance has been significantly improved.

[0023] (5) By designing the elemental composition of the amorphous multi-component silicon-based ceramic and regulating its crystallization characteristics, adjustable dielectric behavior can be obtained, and it is easy to optimize high-temperature resistant coatings with excellent electromagnetic microwave absorption performance.

[0024] (6) The preparation process of the polymer pyrolysis to prepare the amorphous multi-component silicon-based ceramic is simple, easy to operate, has a low sintering temperature, low energy consumption, low preparation cost, is environmentally friendly, and is suitable for large-scale popularization and production. Description of the Drawings

[0025] Figure 1 It is the microscopic morphology diagram of the polymer 1100 °C pyrolyzed multi-component SiZrCN in Comparative Example 1, where (a) is the morphology diagram with a scale of 1 μm, and (b) is the morphology diagram with a scale of 20 nm.

[0026] Figure 2 It is the XRD phase diagram of the polymer 1100 °C pyrolyzed multi-component SiBCN in Comparative Example 3.

[0027] Figure 3 It is the XRD phase diagrams of the polymer pyrolyzed multi-component SiZrBCN at different temperatures in Comparative Examples 5 - 7.

[0028] Figure 4Dielectric constant diagrams of different silicon-based ceramics pyrolyzed from Polymer 1100 °C in Comparative Example 1, Comparative Example 3, Comparative Example 5, and Comparative Example 10, where (a) is the real part diagram of the dielectric constant and (b) is the imaginary part diagram of the dielectric constant.

[0029] Figure 5 Dielectric constant diagrams of polymer pyrolyzed multi-component SiZrBCN at different temperatures in Comparative Example 5, Comparative Example 6, and Comparative Example 7, where (a) is the real part diagram of the dielectric constant and (b) is the imaginary part diagram of the dielectric constant.

[0030] Figure 6 Graph of the microwave absorption performance of polymer pyrolyzed multi-component SiZrBCN in Comparative Example 5, Comparative Example 6, and Comparative Example 7 varying with temperature.

[0031] Figure 7 Microwave absorption performance diagram of the microwave absorption coating of polymer pyrolyzed multi-component SiZrBCN doped with SiC in Example 4.

[0032] Figure 8 Physical diagram of the sample of the polymer pyrolyzed multi-component SiZrCN ceramic microwave absorption coating prepared by the integrated molding process in Comparative Example 2.

[0033] Figure 9 Schematic diagram of the variable-temperature adhesion test of the polymer pyrolyzed multi-component SiZrCN ceramic microwave absorption coating in Comparative Example 2.

[0034] Figure 10 Comparison diagram of the adhesion force of the integrated molding microwave absorption coating of polymer pyrolyzed multi-component SiZrCN in Comparative Example 2 and the adhesion force of the coating prepared by the traditional coating process in Comparative Example 9. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the following embodiments of the present invention can be obtained through the market or prepared by existing methods.

[0037] The anhydrous toluene used in the present invention has a purity of ≥99.8%, the diameter of carbon nanotubes (CNTs) is 1 nm - 2 nm, and the purity is ≥99%; the diameter of carbon fiber is 7 μm, the length is 1 mm - 5 mm, and the purity is ≥99%; the particle size of Ti3AlC2 is 1 μm, and the purity is ≥99%; the average particle size of SiC powder is 30 nm, and the purity is ≥99%.

[0038] Polyborosilazane PBSZ was prepared according to the preparation method in Synthesis and Characterization of a New Liquid Polymer Precursor for Si - B - C - N Ceramics published by Zhang Zongbo et al. in Journal of Materials Science in 2011.

[0039] Comparative Example 1 A preparation method of polymer - pyrolyzed multi - component SiZrCN ceramic microwave - absorbing nano - powder includes the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar atmosphere, polysilazane HTT1800 was dissolved in anhydrous toluene to obtain a first solution, and the mass ratio of polysilazane HTT1800 to anhydrous toluene was 1:5.

[0040] Step 2: Introduction of temperature - resistant and dielectric - behavior - regulating elements: Under an Ar atmosphere, zirconium bis(dimethylamido) (Zr[N(CH3)2]4) was slowly dropped into the first solution at a rate of 30 drops / min to obtain a second solution; the molar ratio of silicon in polysilazane HTT1800 in Step 1 to zirconium in zirconium bis(dimethylamido) in Step 2 was 1:0.1.

[0041] Step 3: Under an Ar atmosphere, the second solution was placed in a container and heated in a pyrolysis furnace at a heating rate of 2 °C / min, and cured at 250 °C for 2 h to obtain a cured sample.

[0042] Step 6: Under an Ar atmosphere, the cured sample was pyrolyzed at 1100 °C for 2 h, and the heating and cooling rates were both 3 °C / min, thus obtaining the polymer - pyrolyzed multi - component SiZrCN ceramic microwave - absorbing nano - powder.

[0043] Comparative Example 2 A preparation method of polymer - pyrolyzed multi - component SiZrCN ceramic microwave - absorbing coating includes the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar atmosphere, polysilazane HTT1800 was dissolved in anhydrous toluene to obtain a first solution, and the mass ratio of polysilazane HTT1800 to anhydrous toluene was 1:5.

[0044] Step 2: Introduction of temperature-resistant and dielectric behavior regulating elements: Under an Ar atmosphere, zirconium bis(dimethylamido) (Zr[N(CH3)2]4) was slowly dropped into the first solution at a rate of 30 drops / min to obtain a second solution; the molar ratio of silicon in polysilazane HTT1800 in Step 1 to zirconium in zirconium bis(dimethylamido) in Step 2 was 1:0.1.

[0045] Step 3: Coating: Using a vacuum spin-coating process, the second solution was uniformly coated onto a clean silicon wafer at a spin-coating speed of 1000 rpm for 20 s to obtain a coated substrate.

[0046] Step 4: Curing: Under an Ar atmosphere, the coated substrate was placed in a cracking furnace and heated at a heating rate of 2 °C / min, and cured at 250 °C for 2 h to form a coating thickness of 0.3 mm to obtain a cured sample.

[0047] Step 5: Under an Ar atmosphere, the cured sample can be coated multiple times, repeating Step 3 and Step 4 until the coating reaches 1.2 mm to obtain a cured substrate sample.

[0048] Step 6: Pyrolysis: Under an Ar atmosphere, the cured substrate sample was pyrolyzed at 1100 °C for 2 h, and the heating and cooling rates were both 3 °C / min to obtain a polymer pyrolyzed multi-component SiZrCN ceramic absorbing coating.

[0049] Example 1 A preparation method of a polymer pyrolyzed multi-component SiZrCN ceramic absorbing coating doped with carbon nanotubes, comprising the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar atmosphere, polysilazane HTT1800 was dissolved in anhydrous toluene to obtain a first solution, and the mass ratio of polysilazane HTT1800 to anhydrous toluene was 1:5.

[0050] Step 2: Introduction of temperature-resistant and dielectric behavior regulating elements: Under an Ar atmosphere, zirconium bis(dimethylamido) (Zr[N(CH3)2]4) was slowly dropped into the first solution at a rate of 30 drops / min to obtain a second solution; the molar ratio of silicon in polysilazane HTT1800 in Step 1 to zirconium in zirconium bis(dimethylamido) in Step 2 was 1:0.1.

[0051] Step 3: Introduction of wave-absorbing modification components: Using an ultrasonic dispersion process, under an Ar atmosphere, carbon nanotubes (CNTs) were added at 1 wt.% of the mass of the second solution, and the CNTs were uniformly dispersed in the second solution, and ultrasonic treatment was carried out for 1 h to obtain a third solution.

[0052] Step 4: Coating: Using the vacuum spin-coating process, uniformly coat the third solution onto a clean silicon wafer at a spin speed of 1000 rpm for 20 s to obtain the coated substrate.

[0053] Step 5: Curing: Under an Ar gas atmosphere, place the coated substrate in a cracking furnace and heat it up at a heating rate of 2 °C / min. Cure it at 250 °C for 2 h to form a coating thickness of 0.3 mm.

[0054] Step 6: Under an Ar gas atmosphere, the cured sample can be coated multiple times. Repeat Step 4 and Step 5 until the coating reaches 1.2 mm to obtain the cured substrate sample.

[0055] Step 7: Pyrolysis: Under an Ar gas atmosphere, pyrolyze the cured substrate sample at 1100 °C for 2 h with a heating and cooling rate of 3 °C / min to obtain the doped carbon nanotube polymer pyrolyzed multi-component SiZrCN ceramic microwave absorbing coating.

[0056] Example 2 A preparation method of a doped carbon fiber polymer pyrolyzed multi-component SiZrCN ceramic microwave absorbing coating, comprising the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar gas atmosphere, dissolve polysilazane HTT1800 in anhydrous toluene to obtain the first solution. The mass ratio of polysilazane HTT1800 to anhydrous toluene is 1:5.

[0057] Step 2: Introduction of temperature-resistant and dielectric behavior regulating elements: Under an Ar gas atmosphere, slowly drop zirconium bis(dimethylamido) (Zr[N(CH3)2]4) into the first solution at a rate of 30 drops / min to obtain the second solution; the molar ratio of silicon in polysilazane HTT1800 in Step 1 to zirconium in zirconium bis(dimethylamido) in Step 2 is 1:0.1.

[0058] Step 3: Introduction of microwave absorbing modification components: Using the ultrasonic dispersion process, under an Ar gas atmosphere, uniformly disperse carbon fibers accounting for 1 wt.% of the mass of the second solution into the second solution to obtain the third solution; the ultrasonic time is 1 h.

[0059] Step 4: Coating: Using the vacuum spin-coating process, uniformly coat the third solution onto a clean silicon wafer at a spin speed of 1500 rpm for 30 s to obtain the coated substrate.

[0060] Step 5: Curing: Under an Ar gas atmosphere, place the coated substrate in a cracking furnace and heat it up at a heating rate of 2 °C / min. Cure it at 250 °C for 2 h to form a coating thickness of 0.3 mm to obtain the cured sample.

[0061] Step 6: Under an Ar atmosphere, the cured sample can be coated multiple times. Repeat Step 4 and Step 5 until the coating reaches 1.2 mm, obtaining the cured substrate sample.

[0062] Step 7: Pyrolysis: Under an Ar atmosphere, pyrolyze the cured substrate sample at 1100 °C for 2 h with both the heating and cooling rates being 3 °C / min, obtaining a polymer-derived multi-component SiZrCN ceramic absorbing coating doped with carbon fibers.

[0063] Comparative Example 3 A preparation method of a polymer-derived multi-component SiBCN ceramic absorbing nano-powder, comprising the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar atmosphere, dissolve polyborosilazane PBSZ in anhydrous toluene to obtain a first solution, with the mass ratio of polyborosilazane PBSZ to anhydrous toluene being 1:5.

[0064] Step 2: Curing: Under an Ar atmosphere, load the first solution into a container and place it in a pyrolysis furnace for heating at a heating rate of 2 °C / min, and cure at 250 °C for 2 h.

[0065] Step 3: Pyrolysis: Under an Ar atmosphere, pyrolyze the cured sample at 1100 °C for 2 h with both the heating and cooling rates being 3 °C / min, obtaining SiBCN ceramic absorbing nano-powder.

[0066] Comparative Example 4 A preparation method of a polymer-derived multi-component SiBCN ceramic absorbing coating, comprising the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar atmosphere, dissolve polyborosilazane PBSZ in anhydrous toluene to obtain a first solution, with the mass ratio of polyborosilazane PBSZ to anhydrous toluene being 1:5.

[0067] Step 2: Coating: Adopt a vacuum spin-coating process to uniformly coat the first solution onto a clean silicon wafer at a spin-coating speed of 1500 rpm for 30 s, obtaining the coated substrate.

[0068] Step 3: Curing: Under an Ar atmosphere, place the coated substrate in a pyrolysis furnace for heating at a heating rate of 2 °C / min, and cure at 250 °C for 2 h to form a coating thickness of 0.3 mm.

[0069] Step 4: Under an Ar atmosphere, the cured sample can be coated multiple times. Repeat Step 3 and Step 4 until the coating reaches 1.2 mm, obtaining the cured substrate sample.

[0070] Step 5: Pyrolysis: Under an Ar atmosphere, the cured substrate sample is pyrolyzed at 1100 °C for 2 h with both the heating and cooling rates being 3 °C / min to obtain the SiBCN ceramic microwave absorption coating.

[0071] Example 3 A preparation method of a doped titanium aluminum carbide polymer pyrolysis multi-component SiBCN ceramic microwave absorption coating, comprising the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar atmosphere, polyborosilazane PBSZ is dissolved in anhydrous toluene to obtain a first solution, and the mass ratio of polyborosilazane PBSZ to anhydrous toluene is 1:5.

[0072] Step 2: Introduction of microwave absorption modification components: By means of ultrasonic dispersion process, under an Ar atmosphere, 1 wt.% of Ti3AlC2 based on the mass of the first solution is uniformly dispersed into the first solution to obtain a second solution; the ultrasonic time is 1 h.

[0073] Step 3: Coating: By means of vacuum spin coating process, the second solution is uniformly coated on a clean silicon wafer at a spin coating speed of 1500 rpm for 30 s to obtain the coated substrate.

[0074] Step 4: Curing: Under an Ar atmosphere, the coated substrate is placed in a pyrolysis furnace for heating at a heating rate of 2 °C / min and cured at 250 °C for 2 h to form a coating thickness of 0.3 mm.

[0075] Step 5: Under an Ar atmosphere, the cured sample can be coated multiple times, repeating Step 3 and Step 4 until the coating finally reaches 1.2 mm.

[0076] Step 6: Pyrolysis: Under an Ar atmosphere, the cured substrate sample is pyrolyzed at 1100 °C for 2 h with both the heating and cooling rates being 3 °C / min to obtain the doped titanium aluminum carbide SiBCN ceramic microwave absorption coating.

[0077] Comparative Example 5 A preparation method of a polymer pyrolysis multi-component SiZrBCN ceramic microwave absorption nanopowder, comprising the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar atmosphere, polysilazane HTT1800 is dissolved in anhydrous toluene to obtain a first solution, and the mass ratio of polysilazane HTT1800 to anhydrous toluene is 1:5.

[0078] Step 2: Introduction of temperature-resistant and dielectric behavior regulating element Zr: Under an Ar atmosphere, zirconium bis(ethylmethylamide) (Zr[N(CH3)2]4) was slowly dropped into the first solution at a rate of 30 drops / min to obtain a second solution; the molar ratio of silicon in polysilazane HTT1800 in Step 1 to zirconium in zirconium bis(ethylmethylamide) in Step 2 was 1:0.1.

[0079] Step 3: Introduction of temperature-resistant and dielectric behavior regulating element B: Under magnetic stirring, the second solution was immersed in a mixed solution of acetone and dry ice at -78 °C for standby. Then, borane dimethyl sulfide (BH3∙(CH3)2S) complex was used as the boron source and was gradually dropped into the second solution at a rate of 20 drops / min. The molar ratio of zirconium in zirconium bis(ethylmethylamide) to boron in borane dimethyl sulfide was 1:0.5, and finally, a Zr and B modified HTT1800 solution, i.e., the third solution, was obtained.

[0080] Step 4: Curing: Under an Ar atmosphere, the third solution was placed in a container and heated in a pyrolysis furnace at a heating rate of 2 °C / min and cured at 250 °C for 2 h.

[0081] Step 5: Pyrolysis: Under an Ar atmosphere, the cured sample was pyrolyzed at 1100 °C for 2 h, and the heating and cooling rates were both 5 °C / min, and polymer pyrolyzed amorphous SiZrBCN powder could be obtained.

[0082] Comparative Example 6 A preparation method of polymer pyrolyzed multi-component SiZrBCN ceramic absorbing nano-powder, comprising the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar atmosphere, polysilazane HTT1800 was dissolved in anhydrous toluene to obtain a first solution, and the mass ratio of polysilazane HTT1800 to anhydrous toluene was 1:5.

[0083] Step 2: Introduction of temperature-resistant and dielectric behavior regulating element Zr: Under an Ar atmosphere, zirconium bis(ethylmethylamide) (Zr[N(CH3)2]4) was slowly dropped into the first solution at a rate of 30 drops / min to obtain a second solution; the molar ratio of silicon in polysilazane HTT1800 in Step 1 to zirconium in zirconium bis(ethylmethylamide) in Step 2 was 1:0.1.

[0084] Step 3: Introduction of element B for regulating temperature resistance and dielectric behavior: Under the condition of magnetic stirring, immerse the second solution in a mixed solution of acetone and dry ice at -78 °C for standby. Then, take borane dimethyl sulfide (BH3∙(CH3)2S) complex as the boron source and add it dropwise to the second solution at a rate of 20 drops / min. The molar ratio of zirconium in zirconium tetrakis(dimethylamido) in Step 2 to boron in borane dimethyl sulfide in Step 3 is 1:0.5. Finally, obtain the HTT1800 solution modified by Zr and B, that is, the third solution.

[0085] Step 4: Curing: Under an Ar gas atmosphere, place the third solution in a container and heat it up in a cracking furnace at a heating rate of 2 °C / min, and cure it at 250 °C for 2 h.

[0086] Step 5: Pyrolysis: Under an Ar gas atmosphere, pyrolyze the cured sample at 1100 °C for 2 h, and the heating and cooling rates are both 2 °C / min, then the polymer pyrolysis amorphous SiZrBCN coating can be obtained.

[0087] Step 6: Sintering: Sinter the amorphous SiZrBCN coating obtained in Step 5 at 1300 °C for 2 h under a N2 protective atmosphere. The heating and cooling rates are as follows: the heating rate is 5 °C / min during the period from room temperature to 1100 °C, and the heating rate is 5 °C / min during the period from 1100 °C to 1300 °C, then the SiZrBCN ceramic absorbing nano-powder can be obtained.

[0088] Comparative Example 7 A preparation method of polymer pyrolysis multi-component SiZrBCN ceramic absorbing nano-powder, comprising the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar gas atmosphere, dissolve polysilazane HTT1800 in anhydrous toluene to obtain the first solution, and the mass ratio of polysilazane HTT1800 to anhydrous toluene is 1:5.

[0089] Step 2: Introduction of element Zr for regulating temperature resistance and dielectric behavior: Under an Ar gas atmosphere, slowly drop zirconium tetrakis(dimethylamido) (Zr[N(CH3)2]4) into the first solution at a rate of 30 drops / min to obtain the second solution; the molar ratio of silicon in polysilazane HTT1800 in Step 1 to zirconium in zirconium tetrakis(dimethylamido) in Step 2 is 1:0.1.

[0090] Step 3: Introduction of the temperature-resistant and dielectric behavior regulating element B: Under the condition of magnetic stirring, soak the second solution in a mixed solution of acetone and dry ice at -78 °C for standby. Then, take borane dimethyl sulfide (BH3∙(CH3)2S) complex as the boron source and add it dropwise to the second solution at a rate of 20 drops / min. The molar ratio of zirconium in zirconium bis(dimethylamido) in Step 2 to boron in borane dimethyl sulfide in Step 3 is 1:0.5, and finally obtain the HTT1800 solution modified by Zr and B, that is, the third solution.

[0091] Step 4: Curing: Under an Ar gas atmosphere, put the third solution into a container and place it in a cracking furnace for heating. The heating rate is 2 °C / min, and cure at 250 °C for 2 h.

[0092] Step 5: Pyrolysis: Under an Ar gas atmosphere, pyrolyze the cured sample at 1100 °C for 2 h. The heating rate and the cooling rate are both 2 °C / min, and then the polymer pyrolyzed amorphous SiZrBCN coating can be obtained.

[0093] Step 6: Sintering: Sinter the pyrolyzed amorphous SiZrBCN coating in Step 5 under a N2 protective atmosphere. First, sinter at 1300 °C for 2 h, then heat up to 1500 °C and sinter for 2 h. The heating and cooling rate is as follows: the heating rate is 5 °C / min during the period from room temperature to 1100 °C, and the heating rate is 5 °C / min during the periods of 1100 °C - 1300 °C and 1300 °C - 1500 °C, and then the SiZrBCN ceramic microwave absorbing nano-powder can be obtained.

[0094] Comparative Example 8 A preparation method of a polymer pyrolyzed multi-component SiZrBCN ceramic microwave absorbing coating, comprising the following steps: Step 1: Preparation of the organosilicon precursor: Under an Ar gas atmosphere, dissolve polysilazane HTT1800 in anhydrous toluene (purity ≥ 99.8%) to obtain the first solution. The mass ratio of polysilazane HTT1800 to anhydrous toluene is 1:5.

[0095] Step 2: Introduction of the temperature-resistant and dielectric behavior regulating element Zr: Under an Ar gas atmosphere, slowly drop zirconium bis(dimethylamido) (Zr[N(CH3)2]4) into the first solution at a rate of 30 drops / min to obtain the second solution; the molar ratio of silicon in polysilazane HTT1800 in Step 1 to zirconium in zirconium bis(dimethylamido) in Step 2 is 1:0.1.

[0096] Step 3: Introduction of temperature-resistant and dielectric behavior regulating element B: Under the condition of magnetic stirring, soak the second solution in a mixed solution of acetone and dry ice at -78 °C for standby. Then, take borane dimethyl sulfide (BH3∙(CH3)2S) complex as the boron source and add it dropwise to the second solution at a rate of 20 drops / min. The molar ratio of zirconium in tetrakis(dimethylamino)zirconium to boron in borane dimethyl sulfide is 1:0.5. Finally, obtain the HTT1800 solution modified by Zr and B, that is, the third solution.

[0097] Step 4: Coating: Adopt the vacuum spin-coating process to uniformly coat the third solution onto a clean SiC substrate at a spin-coating speed of 2000 rpm for 30 s to obtain the coated substrate.

[0098] Step 5: Curing: Under an Ar gas atmosphere, place the coated substrate in a cracking furnace and heat it up at a heating rate of 2 °C / min, and cure it at 250 °C for 2 h to form a coating thickness of 0.3 mm.

[0099] Step 6: Under an Ar gas atmosphere, the cured sample can be coated multiple times. Repeat Step 4 and Step 5 until the coating reaches 1.2 mm.

[0100] Step 7: Pyrolysis: Under an Ar gas atmosphere, pyrolyze the cured substrate sample at 1100 °C for 2 h, and the heating and cooling rates are both 2 °C / min, then the substrate with a polymer pyrolyzed amorphous SiZrBCN coating can be obtained.

[0101] Step 8: Sintering: Sinter the substrate with the polymer pyrolyzed amorphous SiZrBCN coating in Step 7 under a N2 protective atmosphere. First, sinter it at 1300 °C for 2 h, then heat it up to 1500 °C and sinter it for 2 h. The heating and cooling rates are as follows: the heating rate is 5 °C / min from room temperature to 1100 °C, and the heating rates are 5 °C / min during 1100 °C - 1300 °C and 1300 °C - 1500 °C. Then the SiZrBCN ceramic absorbing coating can be obtained.

[0102] Example 4 A preparation method of a doped SiC polymer pyrolyzed multi-component SiZrBCN ceramic absorbing coating, comprising the following steps: Step 1: Preparation of organosilicon precursor: Under an Ar gas atmosphere, dissolve polysilazane HTT1800 in anhydrous toluene to obtain the first solution. The mass ratio of polysilazane HTT1800 to anhydrous toluene is 1:5.

[0103] Step 2: Introduction of temperature resistance and dielectric behavior regulating element Zr: Under an Ar gas atmosphere, zirconium bis(dimethylamido) (Zr[N(CH3)2]4) was slowly dropped into the first solution at a rate of 30 drops / min to obtain the second solution; the molar ratio of silicon in the organosilane to zirconium in zirconium bis(dimethylamido) in Step 1 and Step 2 was 1:0.1.

[0104] Step 3: Introduction of temperature resistance and dielectric behavior regulating element B: While maintaining the magnetic stirring condition, the second solution was immersed in an acetone-dry ice mixture at -78 °C for standby. Then, borane dimethyl sulfide (BH3∙(CH3)2S) complex was used as the boron source and was added dropwise to the second solution at a rate of 20 drops / min. The molar ratio of zirconium in zirconium bis(dimethylamido) to boron in borane dimethyl sulfide was 1:0.5, and finally, the Zr and B modified HTT1800 solution, that is, the third solution, was obtained.

[0105] Step 4: Introduction of wave-absorbing modification components: Using the ultrasonic dispersion process, under an Ar gas atmosphere, 1 wt.% of SiC powder based on the mass of the third solution was uniformly dispersed into the third solution and ultrasonicated for 1 h to obtain the fourth solution.

[0106] Step 5: Coating: Using the vacuum spin-coating process, the fourth solution was uniformly coated onto a clean SiC substrate at a spin-coating speed of 2000 rpm for 30 s to obtain the coated substrate.

[0107] Step 6: Curing: Under an Ar gas atmosphere, the coated substrate was placed in a cracking furnace for heating at a heating rate of 2 °C / min and cured at 250 °C for 2 h to form a coating thickness of 0.3 mm.

[0108] Step 7: Under an Ar gas atmosphere, the cured sample can be coated multiple times, repeating Step 5 and Step 6, and finally the coating reaches 1.2 mm to obtain the cured substrate sample.

[0109] Step 8: Pyrolysis: Under an Ar gas atmosphere, the cured substrate sample was pyrolyzed at 1100 °C for 2 h, and the heating and cooling rates were both 2 °C / min, and the substrate with a polymer pyrolyzed amorphous SiZrBCN coating could be obtained.

[0110] Step 8: Sintering: The substrate with the polymer pyrolyzed amorphous SiZrBCN coating in Step 7 was sintered at 1300 °C for 2 h under a N2 protective atmosphere, and then heated to 1500 °C and sintered for 2 h. The heating and cooling rates were as follows: the heating rate was 10 °C / min from room temperature to 1100 °C, and the heating rates were 5 °C / min during 1100 °C - 1300 °C and 1300 °C - 1500 °C, and the SiZrBCN ceramic wave-absorbing coating doped with SiC could be obtained.

[0111] Comparative Example 9 A SiZrCN wave-absorbing coating prepared by a traditional coating process, comprising the following steps: Step 1: Grinding: Thoroughly grind the polymer-cracked multi-component SiZrCN ceramic wave-absorbing nano powder prepared in Comparative Example 2, and pass through a 200-500 mesh sieve to obtain the wave-absorbing powder.

[0112] Step 2: Mixing: Mix the wave-absorbing powder with liquid epoxy resin E-51 at a mass ratio of 1:10, and simultaneously add a polyetheramine D230 curing agent, where the mass ratio of the curing agent to the epoxy resin is 1:2. Adopt an ultrasonic dispersion process to obtain a mixed liquid.

[0113] Step 3: Coating: Adopt a spin coating process to uniformly coat the mixed liquid onto the surface of the nickel-based superalloy GH3128 at a spin coating speed of 1000 rpm for 20 s to obtain the coated substrate.

[0114] Step 4: Curing: In an air atmosphere, place the coated substrate in a cracking furnace and heat it up at a heating rate of 2 °C / min, and cure it at 100 °C for 4 h to obtain the SiZrCN wave-absorbing coating.

[0115] Comparative Example 10 A preparation method of a polymer-cracked multi-component SiCN ceramic wave-absorbing nano powder, comprising the following steps: Step 1: Preparation of organosilicon precursor: In an Ar gas atmosphere, dissolve polysilazane HTT1800 in anhydrous toluene to obtain a first solution, and the mass ratio of polysilazane HTT1800 to anhydrous toluene is 1:5.

[0116] Step 2: In an Ar gas atmosphere, place the first solution in a container and place it in a cracking furnace to heat it up at a heating rate of 2 °C / min, and cure it at 250 °C for 2 h to obtain a cured sample.

[0117] Step 3: In an Ar gas atmosphere, subject the cured sample to high-temperature cracking at 1100 °C for 2 h, and the heating and cooling rates are both 3 °C / min to obtain the polymer-cracked multi-component SiZrCN ceramic wave-absorbing nano powder.

[0118] It should be noted that the polymers prepared in Comparative Example 1, Comparative Example 3, Comparative Example 4, Comparative Example 6, and Comparative Example 7 are used as a reference group to illustrate the wave-absorbing performance of the pure sample polymer-cracked multi-component silicon-based ceramic material itself.

[0119] Figure 1 The microscopic morphology diagram of the polymer-cracked multi-component SiZrCN ceramic wave-absorbing nano powder obtained in Comparative Example 1. From Figure 1It can be clearly seen that there are no lattice fringes that should be present in the crystal in the high-resolution transmission electron microscope image, and at the same time, the selected area electron diffraction shows typical amorphous characteristics, indicating that the SiZrCN ceramic absorbing nano-powder prepared in Comparative Example 1 is in an amorphous phase.

[0120] Figure 2 It is the XRD phase diagram of the polymer 1100 °C pyrolyzed multi-component SiBCN in Comparative Example 3. The abscissa is twice the diffraction angle, denoted as 2-θ, with the unit of degree; the ordinate is the X-ray intensity. It can be clearly seen from the XRD pattern that the sample prepared in Comparative Example 3 has no sharp diffraction peaks, indicating that the prepared SiBCN is amorphous.

[0121] Figure 3 It is the XRD phase diagram of the polymer pyrolyzed multi-component SiZrBCN at different temperatures in Comparative Examples 5 to 7. The abscissa is twice the diffraction angle, denoted as 2-θ, with the unit of degree; the ordinate is the X-ray intensity. It can be clearly seen from the XRD pattern that the coated sample calcined in N2 atmosphere at 1300 °C is basically amorphous, and the coated sample calcined at 1500 °C already contains crystalline phases such as SiC, ZrCN, and Si3N4. With the change of the heat treatment temperature, the microstructure of amorphous SiZrBCN changes, forming a microstructure in which nano-phases are dispersed in the amorphous matrix phase.

[0122] Figure 4 It is the dielectric constant diagram of the polymers pyrolyzed different silicon-based ceramics at 1100 °C in Comparative Example 1, Comparative Example 3, Comparative Example 5 and Comparative Example 10. The abscissa represents the frequency of the electromagnetic wave, with the unit of: GHz; the ordinate represents the dielectric constant, where is the real part of the dielectric constant, is the imaginary part of the dielectric constant. It can be seen from Figure 4 that for the four ceramic materials SiCN, SiBCN, SiZrCN, and SiZrBCN, in the frequency range of 2 GHz to 18 GHz, SiCN has the highest real and imaginary parts of the dielectric constant, indicating that its loss ability to electromagnetic waves is the best. However, for the three ceramic materials with introduced regulating elements, with the increase in the type of doping elements, both the real and imaginary parts of the dielectric constant have been improved to a certain extent. This may be because increasing the type of elements will significantly improve the electrical conductivity of the ceramic matrix, enhance the conduction loss, and at the same time increase the defects and improve the defect loss. This rule shows that by introducing regulating elements and increasing the number of regulating elements, on the one hand, the electrical conductivity of the ceramic can be improved, enhancing the conduction loss of electromagnetic waves, and on the other hand, the type of defects is increased, improving the loss of electromagnetic waves by defect polarization. Under the combined action, the microwave absorption performance of the ceramic is improved. The dielectric behavior of the polymer pyrolyzed multi-component silicon-based ceramics can be regulated in a wide temperature range, which provides guidance for the design of high-impedance matching high-temperature microwave absorption materials.

[0123] Figure 5 Dielectric constant graphs of polymer pyrolysis multi - SiZrBCN in Comparative Example 5, Comparative Example 6 and Comparative Example 7 at different temperatures. The abscissa represents the frequency of electromagnetic waves, with the unit of GHz; the ordinate represents the dielectric constant, where is the real part of the dielectric constant, and Figure 5 is the imaginary part of the dielectric constant. It can be clearly observed from

[0124] Figure 6 that as the sintering temperature increases, both the real part and the imaginary part of the dielectric constant of the prepared polymer pyrolysis multi - SiZrBCN are significantly improved in the frequency range of 2 GHz to 18 GHz. This is mainly because a high sintering temperature is conducive to the formation of the crystalline SiZrBCN phase, which is the key factor affecting the electromagnetic parameters of SiZrBCN ceramics. This indicates that by adjusting the sintering temperature, the dielectric behavior of polymer pyrolysis multi - silicon - based ceramics can be regulated within a wide temperature range, which has important guiding significance for designing ceramic materials with excellent wave - absorbing properties. Figure 6 This is the graph of the wave - absorbing performance of polymer pyrolysis multi - SiZrBCN in Comparative Example 5, Comparative Example 6 and Comparative Example 7 changing with temperature. The abscissa represents the frequency of electromagnetic waves, with the unit of GHz; the ordinate represents the electromagnetic wave reflectivity, with the unit of - dB. It can be clearly seen from

[0125] Figure 7 that as the temperature increases, the wave - absorbing performance of polymer pyrolysis multi - SiZrBCN in Comparative Example 5 is significantly improved, indicating that a high sintering temperature is conducive to the formation of the SiZrBCN crystal phase, and high crystallinity is the key factor determining the wave - absorbing performance of ceramic materials. In particular, the sample calcined at 1500 °C in this example shows broadband electromagnetic absorption potential in the X and Ku bands. This fully demonstrates the application potential of polymer pyrolysis multi - SiZrBCN ceramics as radar wave absorbers. Figure 6 In comparison, from Figure 10It can be clearly seen that after doping with the wave-absorbing modification component SiC, the wave-absorbing performance of the polymer pyrolysis multi-component SiZrBCN wave-absorbing coating has been significantly improved. This is mainly because after introducing SiC, the conductance loss of the wave-absorbing coating to electromagnetic waves has been increased. At the same time, there are rich interfaces between SiC and the SiZrBCN matrix, which also significantly enhances the loss of interfacial polarization. Under the superposition of multiple loss mechanisms, the wave-absorbing performance of the doped SiC polymer pyrolysis multi-component SiZrBCN wave-absorbing coating has been significantly improved compared with the pure sample SiZrBCN, which undoubtedly enhances the application value of the polymer pyrolysis multi-component SiZrBCN ceramic as a radar wave absorber.

[0126] Figure 8 Figure 4 shows the physical diagram of the polymer pyrolysis multi-component SiZrCN ceramic wave-absorbing coating sample prepared by the integrated molding process for Comparative Example 2. From Figure 8 it can be seen that through the integrated molding process, a coating with good compactness and uniform adhesion has been successfully prepared, which indicates that the integrated molding process developed in the present invention has sufficient feasibility.

[0127] Figure 9 Figure 5 is a schematic diagram of the variable-temperature adhesion test of the polymer pyrolysis multi-component SiZrCN ceramic wave-absorbing coating for Comparative Example 2. According to the national standard requirements, a test method for the shear bond strength of the wave-absorbing coating with variable-temperature test function was designed. On a universal mechanical testing machine, the bond strength between the coating and the substrate was evaluated through the shear tensile action of the substrate.

[0128] Figure 10 Figure 6 is a comparison chart of the adhesion force test data of the polymer pyrolysis multi-component silicon-based ceramic wave-absorbing coating prepared by the integrated coating molding method for Comparative Example 2 and the adhesion force test data of the coating prepared by the traditional coating process for Comparative Example 9. The abscissa represents temperature, unit: °C; the ordinate is the shear strength, unit MPa. From Figure 10 it can be found that at lower temperatures, the coating prepared by the traditional coating process, due to the excellent bonding performance of the adhesive material, the shear bond strength of the coating is significantly better than that of the integrated coating molding process. However, as the temperature increases, the bonding performance of the adhesive material deteriorates rapidly, resulting in a significant reduction in the bonding strength of the traditional coating. In contrast, the coating prepared by the integrated coating molding process effectively avoids this problem and exhibits a high shear bond strength. The results of the comparative experiment show that the integrated coating molding process developed in the present invention has obvious technical advantages in the application field of high-temperature wave-absorbing coatings.

[0129] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0130] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A preparation method of a polymer pyrolysis multi - silicon - based ceramic microwave - absorbing coating, characterized in that, It includes the following steps: Under a protective atmosphere, dissolve the organosilane in an organic solvent to obtain a first solution; Add a wave-absorbing modification component to the first solution to obtain a second solution; Under a protective atmosphere, coat the second solution on a substrate material, cure it at 120°C to 300°C, and then pyrolyze it at 900°C to 1100°C to obtain a polymer pyrolysis multi-silicon-based ceramic wave-absorbing coating.

2. The preparation method of a polymer pyrolysis multi-silicon-based ceramic microwave absorbing coating according to claim 1, characterized in that, The addition amount of the wave-absorbing modification component is 1% to 3% of the mass of the second solution.

3. The preparation method of a polymer pyrolysis multi-silicon-based ceramic microwave absorption coating according to claim 1, characterized in that It also includes that after pyrolysis, under a protective atmosphere, calcine it at 1300°C to 1600°C.

4. The preparation method of a polymer pyrolysis multi - silicon - based ceramic microwave - absorbing coating according to claim 1, characterized in that, The calcination temperature is 2h to 5h.

5. The preparation method of a polymer pyrolysis multi - silicon - based ceramic microwave - absorbing coating according to claim 1, characterized in that, The curing time is 60min to 180min.

6. The preparation method of a polymer pyrolysis multi - silicon - based ceramic wave - absorbing coating according to claim 1, characterized in that, The pyrolysis time is 60min to 120min.

7. The preparation method of a polymer-cracking multi-silicon-based ceramic microwave absorption coating according to claim 1, characterized in that The mass ratio of the organosilane to the organic solution is 1:4 to 6, and the organosilane is selected from polycarbosilane, polysilazane, polysiloxane or polyborosilazane.

8. The preparation method of a polymer pyrolysis multi - silicon - based ceramic wave - absorbing coating according to claim 1, wherein, It also includes: Add an organic complex to the first solution; The central element of the organic complex is one or two of Zr, Hf, Ti, V, Ta, Al and B.

9. The preparation method of a polymer-cracked multi-silicon-based ceramic microwave absorbing coating according to claim 1, wherein The wave-absorbing modification component is a carbon material, SiC, a ternary layered compound, a metal oxide or a carbide.

10. A polymer pyrolysis multi-silicon-based ceramic wave-absorbing coating prepared by the preparation method according to any one of claims 1-9.

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