SiBCN-Fe ceramic corrosion-resistant wave-absorbing material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of wave-absorbing materials, in particular to a SiBCN-Fe ceramic corrosion-resistant wave-absorbing material and a preparation method and application thereof. The preparation method comprises the following steps: preparing a hyperbranched PBSZ-SiH polymer in an argon atmosphere; under the protection of argon, ferric acetylacetonate is dissolved in anhydrous xylene, and then the hyperbranched PBSZ-SiH polymer is added for a reaction; collecting a solid phase to obtain a PBSZ-Fe ceramic precursor; heating the PBSZ-Fe ceramic precursor, and carrying out a cross-linking reaction; and grinding a product obtained after the cross-linking reaction into powder, and then performing high-temperature pyrolysis in an argon atmosphere to obtain the SiBCN-Fe ceramic. According to the SiBCN-Fe ceramic corrosion-resistant wave-absorbing material, in a 3.5 wt% NaCl / H2O solution, the corrosion potential (Ev) is 0.035 V, the corrosion current density (Icorr) is 6.295 * 10 <-7 > Acm <-2 >, and the SiBCN-Fe ceramic corrosion-resistant wave-absorbing material is superior to most corrosion-resistant wave-absorbing materials; the effective absorption bandwidth (EAB) of 8.16 GHz under 2.7 mm and the minimum reflection loss of-32.2 dB under 2 mm are achieved, and excellent corrosion resistance and excellent wave absorbing performance are achieved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of wave-absorbing materials, in particular to a SiBCN-Fe ceramic corrosion-resistant wave-absorbing material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of the fifth generation communication technology and radar technology, the complex electromagnetic environment puts forward comprehensive requirements of multi-band compatibility, light weight and environmental adaptability on stealth materials, and it is inevitable to develop multifunctional wave-absorbing materials. In the extremely harsh marine environment, materials with high efficient wave-absorbing performance and excellent corrosion resistance are particularly important, which can protect the matrix from corrosion while maintaining the electromagnetic stealth defense capability.

[0003] At present, commonly used wave-absorbing materials include ferrite, carbonyl iron powder, metal oxide, carbon-based material, conductive polymer and ceramic material, etc. Ferrite has high corrosion potential and can efficiently absorb electromagnetic waves through natural resonance and self-polarization effect, and can maintain good corrosion resistance in the marine humid and salty environment for a long time. However, the density of ferrite is very large, in order to reduce the density of ferrite and improve the wave-absorbing capacity, ferrite is often made into hollow, microporous or co-sintered with other low-density materials, and the density of ferrite powder is still in the range of 4.4-5.3 g / cm 3 In order to enhance the corrosion resistance and wave-absorbing performance of the wave-absorbing coating, the thickness of the ferrite wave-absorbing coating often needs to be increased, such as the coating thickness of a certain type of ship reaches 5 mm, which is heavy in overall weight, high in cost and inconvenient to maintain. Carbonyl iron powder has small density (1-2 g / cm 3 ), high saturation magnetization and magnetic loss, and the natural resonance frequency is usually 2-18 GHz, which has excellent wave-absorbing performance at a frequency of 8-18 GHz. However, the high specific surface area and more oxidation active sites of carbonyl iron powder are easily oxidized in high temperature environment, and have poor corrosion resistance in marine environment; in addition, carbonyl iron powder has high surface activity as a kind of active metal powder, is easy to react with water to cause self-corrosion, is easy to absorb moisture and form clumps, and is difficult to be uniformly dispersed in the coating matrix.

[0004] Traditional single-component microwave absorbing materials, such as ferrites and carbonyl iron, suffer from poor dielectric tunability, a single loss mechanism, high density, and susceptibility to corrosion, making them unsuitable for corrosion-resistant microwave absorption. By coating the surface of single-component microwave absorbing materials, such as carbonyl iron powder, with other corrosion-resistant materials, their corrosion resistance can be improved. For example, using trimethylaluminum and water as precursors, alumina is coated onto the surface of carbonyl iron powder using atomic layer deposition (ALD), resulting in significantly improved corrosion resistance and thermal stability, with a maximum oxidation resistance temperature exceeding 550℃. Similarly, in-situ polymerization of a 2-methylimidazole / epoxy resin (2-MI / EP) coating layer on the surface of carbonyl iron powder can also enhance its corrosion resistance. Due to the barrier effect of the coating layer, corrosive media have difficulty penetrating the coating to reach the carbonyl iron powder surface. Although the corrosion current density is reduced and the corrosion potential shifts positively to 0.1, its overall corrosion resistance still needs further improvement.

[0005] Despite numerous improvements and enhancements, conventionally widely used ferrite and carbonyl iron powders still struggle to achieve a balance between microwave absorption performance, corrosion resistance, and performance stability in the unique environment of tropical oceans. Exploring novel microwave absorbing materials for tropical marine environments is of significant fundamental research importance and practical value. Summary of the Invention

[0006] This application provides a SiBCN-Fe ceramic corrosion-resistant microwave absorbing material, its preparation method, and its application, aiming to solve the technical problem that existing microwave absorbing materials cannot simultaneously possess excellent microwave absorption performance and corrosion resistance.

[0007] To achieve the above objectives, the present application adopts the following technical solution.

[0008] The first aspect of this application provides a method for preparing a SiBCN-Fe ceramic corrosion-resistant microwave absorbing material, comprising:

[0009] S1, under an argon atmosphere, dichloromethylvinylsilane was subjected to a hydroboration reaction with a borane-dimethyl sulfide complex to obtain tris(dichloromethylsilylethyl)borane; tris(dichloromethylsilylethyl)borane, dichloromethylsilane and hexamethyldisilazane were subjected to a polycondensation reaction to obtain a crude product; the crude product was purified and cooled to obtain a hyperbranched PBSZ-SiH polymer;

[0010] S2, under argon protection, iron acetylacetone was dissolved in anhydrous xylene, and then hyperbranched PBSZ-SiH polymer was added to react; the solid phase was collected to obtain PBSZ-Fe ceramic precursor;

[0011] S3, the PBSZ-Fe ceramic precursor is heated to carry out a crosslinking reaction; the product after the crosslinking reaction is ground into powder, and then subjected to high-temperature pyrolysis under an argon atmosphere to obtain SiBCN-Fe ceramic.

[0012] Preferred,

[0013] The temperature of the hydroboration reaction is -78℃ to 25℃, and the time is 5 to 24 hours.

[0014] The polycondensation reaction is carried out at a temperature of -78℃ to 25℃ for 2 to 6 hours.

[0015] The purification process specifically involves heating the crude product to 25–220°C to volatilize and remove unreacted monomers and byproducts.

[0016] Preferably, in S1, the molar ratio of dichloromethylvinylsilane, borane-dimethyl sulfide complex, and dichloromethylsilane is 3:1:1, and the amount of hexamethyldisilazane used is in excess.

[0017] Preferably, in S2, the mass ratio of iron acetylacetone to hyperbranched PBSZ-SiH polymer is 1:1 to 3.

[0018] Preferably, the reaction in S2 is carried out at a temperature of 25–180°C for a time of 6–72 h.

[0019] Preferably, the heating rate in S3 is 1 to 10 °C / min;

[0020] The cross-linking reaction is carried out at a temperature of 250–550°C for a time of 0.5–3 hours.

[0021] Preferably, the particle size of the powder in S3 is less than 400 mesh.

[0022] Preferably, the high-temperature pyrolysis temperature in S3 is 1100–1500°C, and the holding time is 2–5 hours.

[0023] In a second aspect, this application provides a SiBCN-Fe ceramic corrosion-resistant microwave absorbing material prepared by the above-described preparation method.

[0024] A third aspect of this application provides the application of the above-mentioned SiBCN-Fe ceramic corrosion-resistant microwave absorbing material as a marine microwave absorbing material for ships.

[0025] Compared with the prior art, the beneficial effects of this application are as follows:

[0026] This application introduces acetylacetone iron, which is easily decomposed, easily dissolved, and has good diffusivity, into the hyperbranched network of PBSZ. SiBCN-Fe ceramic microwave absorbing material with both corrosion resistance and microwave absorption properties is prepared by high-temperature pyrolysis. The process is simple and can be mass-produced.

[0027] This application introduces magnetic particles in situ at the molecular level during the ceramic precursor synthesis stage. After high-temperature pyrolysis, iron and silicon elements form a corrosion-resistant ferrosilicon phase. The catalytically generated carbon layer perfectly coats the ferrosilicon phase, thereby blocking the diffusion of corrosive media and achieving excellent barrier function, thus obtaining excellent anti-corrosion performance. Secondly, after high-temperature pyrolysis, the magnetic particles catalyze the generation of graphite carbon, forming a core-shell structure of C@FeSi phase. While enhancing the dielectric loss of the ceramic, it also generates a large number of defects and heterojunction structures, resulting in a large amount of interfacial polarization loss. In addition, the introduction of magnetic particles forms a multi-mechanism loss synergy, further enhancing the microwave absorption performance.

[0028] The SiBCN-Fe ceramic of this application exhibits a corrosion potential (Ev) of 0.035 V and a corrosion current density (Icorr) of 6.295 × 10⁻⁶ in a 3.5 wt% NaCl / H₂O solution. -7 Acm -2 It outperforms most corrosion-resistant absorbing materials; it achieves an effective absorption bandwidth (EAB) of 8.16 GHz at 2.7 mm and a minimum reflection loss of -32.2 dB at 2 mm, combining excellent corrosion resistance and excellent absorbing performance. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 SEM image of the SiBCN-Fe ceramic prepared in Example 1;

[0031] Figure 2 TEM and elemental distribution diagram of the SiBCN-Fe ceramic prepared in Example 1;

[0032] Figure 3 High-resolution TEM image of the SiBCN-Fe ceramic prepared in Example 1;

[0033] Figure 4 The images show the XRD patterns of the SiBCN-Fe ceramics prepared in Examples 1-3.

[0034] Figure 5 Multiple XRD patterns of the SiBCN-Fe ceramic prepared in Example 1;

[0035] Figure 6 XPS test images of SiBCN-Fe ceramics prepared in Examples 1-3;

[0036] Figure 7 The images show the morphological changes of carbon elements inside the SiBCN-Fe ceramics prepared in Examples 1-3.

[0037] Figure 8 Figure 1 shows the test results of complex permittivity and complex permeability of SiBCN-Fe ceramics prepared in Examples 1-3.

[0038] Figure 9 The graph shows the test results of the reflectance coefficient of the SiBCN-Fe ceramics prepared in Examples 1-3;

[0039] Figure 10 The graph shows the test results of SiBCN-Fe ceramics prepared in Examples 1-3 using RCS simulation.

[0040] Figure 11 The graph shows the test results of the corrosion resistance of SiBCN-Fe ceramics prepared in Examples 1-3. Detailed Implementation

[0041] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0042] In the following description of this embodiment, the terms "including", "comprising", "having", and "containing" are all open-ended terms, meaning that they include but are not limited to.

[0043] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0044] In the following description of this embodiment, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0045] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0046] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0047] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood as each intermediate value between the upper and lower limits of the specifically disclosed range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0048] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this application. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0049] The first aspect of this application involves introducing easily decomposable, easily soluble, and highly diffusible acetylacetone iron as an iron source into a PBSZ hyperbranched network, and then preparing a SiBCN-Fe ceramic microwave absorbing material with both corrosion resistance and microwave absorption properties via high-temperature pyrolysis. The specific preparation method includes:

[0050] S1, under an argon atmosphere, dichloromethylvinylsilane was hydroborized with a boron-dimethyl sulfide complex to obtain tris(dichloromethylsilylethyl)borane; tris(dichloromethylsilylethyl)borane, dichloromethylsilane and hexamethyldisilazane were subjected to a polycondensation reaction to obtain a crude product; the crude product was purified and cooled to obtain a hyperbranched PBSZ-SiH polymer;

[0051] In this application, the preferred molar ratio of dichloromethylvinylsilane, borane-dimethyl sulfide complex, and dichloromethylsilane is 3:1:1, and the amount of hexamethyldisilazane used is in excess.

[0052] The preferred temperature for the hydrogen borylation reaction is -78℃ to 25℃, more preferably 0℃; the preferred reaction time is 5 to 24 hours, more preferably 12 hours.

[0053] The temperature of the polycondensation reaction is -78℃ to 25℃, more preferably 0℃; the time of the polycondensation reaction is 2 to 6 hours, more preferably 4 hours.

[0054] The purification process specifically involves heating the crude product to 25–220°C to evaporate and remove unreacted monomers and byproducts, yielding a pale yellow viscous liquid, namely the hyperbranched PBSZ-SiH polymer.

[0055] S2, under argon protection, iron acetylacetone was dissolved in anhydrous xylene, and then hyperbranched PBSZ-SiH polymer was added to react; the solid phase was collected to obtain PBSZ-Fe ceramic precursor;

[0056] Specifically, under argon protection, ferric acetylacetone is dissolved in anhydrous xylene, and then hyperbranched PBSZ-SiH polymer is added and the mixture is continuously magnetically stirred for 6–72 h to carry out the reaction. The preferred mass ratio of ferric acetylacetone to hyperbranched PBSZ-SiH polymer is 1:1–3; the preferred reaction temperature is 25–180 °C, more preferably 140 °C. Within this reaction temperature, the Si-H groups in PBSZ-SiH and the Fe-O bonds in Fe(acac)3 react to form Si-O-Fe bonds, creating a three-dimensional network cross-linked structure.

[0057] After the reaction was completed, the solvent and byproducts were removed by vacuum distillation to obtain a dark red solid polymer, namely the PBSZ-Fe ceramic precursor.

[0058] S3, the PBSZ-Fe ceramic precursor is heated to carry out a crosslinking reaction; the product after the crosslinking reaction is ground into powder, and then subjected to high-temperature pyrolysis under an argon atmosphere to obtain SiBCN-Fe ceramic.

[0059] Specifically, the PBSZ-Fe ceramic precursor is transferred to a tube furnace and heated to 250–550°C at a heating rate of 1–10°C / min for a crosslinking reaction, with a reaction time of 0.5–3 h. More preferably, the reaction temperature is 400°C and the reaction time is 2 h.

[0060] The cross-linking product was ground in a ball mill, and the powder was passed through a 400-mesh sieve to obtain powder with uniform particle size. Under an argon atmosphere, the temperature was increased to 1100-1500℃ at a heating rate of 5-10℃ / min and held for 2-5 hours for pyrolysis to obtain SiBCN-Fe ceramics. The preferred pyrolysis temperature was 1300℃.

[0061] This application introduces magnetic particles in situ at the molecular level during the ceramic precursor synthesis stage. After high-temperature pyrolysis, iron and silicon elements form a corrosion-resistant ferrosilicon phase. The catalytically generated carbon layer perfectly coats the ferrosilicon phase, thereby blocking the diffusion of corrosive media and achieving excellent barrier function, thus obtaining excellent anti-corrosion performance. Secondly, after high-temperature pyrolysis, the magnetic particles catalyze the generation of graphite carbon, forming a core-shell structure of C@FeSi phase. While enhancing the dielectric loss of the ceramic, it also generates a large number of defects and heterojunction structures, resulting in a large amount of interfacial polarization loss. In addition, the introduction of magnetic particles forms a multi-mechanism loss synergy, further enhancing the microwave absorption performance.

[0062] The SiBCN-Fe ceramic prepared in this application exhibits a corrosion potential (Ev) of 0.035 V and a corrosion current density (Icorr) of 6.295 × 10⁻⁶ in a 3.5 wt% NaCl / H₂O solution. -7 Acm -2 It outperforms most corrosion-resistant absorbing materials; it achieves an effective absorption bandwidth (EAB) of 8.16 GHz at 2.7 mm and a minimum reflection loss of -32.2 dB at 2 mm.

[0063] The SiBCN-Fe ceramic prepared in this application has both excellent corrosion resistance and excellent wave absorption performance, and has a wide range of applications; it can be used as a wave absorbing material for ships in extremely harsh marine environments.

[0064] The present application will be further illustrated by the following examples.

[0065] In the embodiments of this application, the prepared SiBCN-Fe ceramic is labeled as C-Fe. X -T, where C represents ceramic, x represents the amount of iron source added, and T represents the pyrolysis temperature.

[0066] Example 1

[0067] This embodiment provides a method for preparing SiBCN-Fe ceramics, including:

[0068] S1, under an argon atmosphere, 3 mol of dichloromethylvinylsilane (DCMVS) and 1 mol of borane-dimethyl sulfide complex were subjected to a hydroboration reaction at 0 °C for 12 h to obtain tris(dichloromethylsilylethyl)borane (TDSB); then 1 mol of dichloromethylsilane (DCMS) and excess hexamethyldisilazane (HMDZ) were added, and a polycondensation reaction was initiated under a continuous argon flow for 4 h; the reaction system was gradually heated to 180 °C to volatilize and remove unreacted monomers and byproducts, and cooled to room temperature to obtain a pale yellow viscous liquid product, namely the hyperbranched PBSZ-SiH polymer.

[0069] S2, 6g of ferric acetylacetone (Fe(acac)3) was added to 100mL of anhydrous xylene and completely dissolved. Then, 12g of hyperbranched PBSZ-SiH polymer was added, and the reaction was carried out by continuous magnetic stirring at 140℃ for 72h. The reaction product was subjected to vacuum distillation to remove the solvent and byproducts, yielding a dark red solid polymer, namely the PBSZ-Fe ceramic precursor.

[0070] S3. The PBSZ-Fe ceramic precursor was removed from the reaction flask and rapidly transferred to a tube furnace. It was heated to 400°C at a rate of 2°C / min and held under an argon atmosphere for 2 hours to induce a crosslinking reaction. The crosslinking product was then milled in a ball mill for 4 hours, and the powder was passed through a 400-mesh sieve to obtain a uniformly sized powder. Finally, under an argon atmosphere, the powder was heated to 1300°C at a rate of 5°C / min and held for 3 hours for pyrolysis to obtain SiBCN-Fe ceramic, denoted as C-Fe. 0.33 -1300.

[0071] Example 2

[0072] This embodiment provides a method for preparing SiBCN-Fe ceramics, including:

[0073] S1, under an argon atmosphere, 3 mol of dichloromethylvinylsilane (DCMVS) and 1 mol of borane-dimethyl sulfide complex were subjected to a hydroboration reaction at 0 °C for 12 h to obtain tris(dichloromethylsilylethyl)borane (TDSB); then 1 mol of dichloromethylsilane (DCMS) and excess hexamethyldisilazane (HMDZ) were added, and a polycondensation reaction was initiated under a continuous argon flow for 4 h; the reaction system was gradually heated to 180 °C to volatilize and remove unreacted monomers and byproducts, and cooled to room temperature to obtain a pale yellow viscous liquid product, namely the hyperbranched PBSZ-SiH polymer.

[0074] S2, 6g of ferric acetylacetone (Fe(acac)3) was added to 100mL of anhydrous xylene and completely dissolved. Then, 12g of hyperbranched PBSZ-SiH polymer was added, and the reaction was carried out by continuous magnetic stirring at 140℃ for 72h. The reaction product was subjected to vacuum distillation to remove the solvent and byproducts, yielding a dark red solid polymer, namely the PBSZ-Fe ceramic precursor.

[0075] S3. The PBSZ-Fe ceramic precursor was removed from the reaction flask and rapidly transferred to a tube furnace. It was heated to 400°C at a rate of 2°C / min and held under an argon atmosphere for 2 hours to induce a crosslinking reaction. The crosslinking product was then milled in a ball mill for 4 hours, and the powder was passed through a 400-mesh sieve to obtain a uniformly sized powder. Finally, under an argon atmosphere, the powder was heated to 1200°C at a rate of 5°C / min and held for 3 hours for pyrolysis to obtain SiBCN-Fe ceramic, denoted as C-Fe.0.33 -1200.

[0076] Example 3

[0077] This embodiment provides a method for preparing SiBCN-Fe ceramics, including:

[0078] S1, under an argon atmosphere, 3 mol of dichloromethylvinylsilane (DCMVS) and 1 mol of borane-dimethyl sulfide complex were subjected to a hydroboration reaction at 0 °C for 12 h to obtain tris(dichloromethylsilylethyl)borane (TDSB); then 1 mol of dichloromethylsilane (DCMS) and excess hexamethyldisilazane (HMDZ) were added, and a polycondensation reaction was initiated under a continuous argon flow for 4 h; the reaction system was gradually heated to 180 °C to volatilize and remove unreacted monomers and byproducts, and cooled to room temperature to obtain a pale yellow viscous liquid product, namely the hyperbranched PBSZ-SiH polymer.

[0079] S2, 6g of ferric acetylacetone (Fe(acac)3) was added to 100mL of anhydrous xylene and completely dissolved. Then, 12g of hyperbranched PBSZ-SiH polymer was added, and the reaction was carried out by continuous magnetic stirring at 140℃ for 72h. The reaction product was subjected to vacuum distillation to remove the solvent and byproducts, yielding a dark red solid polymer, namely the PBSZ-Fe ceramic precursor.

[0080] S3. The PBSZ-Fe ceramic precursor was removed from the reaction flask and rapidly transferred to a tube furnace. It was heated to 400°C at a rate of 2°C / min and held under an argon atmosphere for 2 hours to induce a crosslinking reaction. The crosslinking product was then milled in a ball mill for 4 hours, and the powder was passed through a 400-mesh sieve to obtain a uniformly sized powder. Finally, under an argon atmosphere, the powder was heated to 1400°C at a rate of 5°C / min and held for 3 hours for pyrolysis to obtain SiBCN-Fe ceramic, denoted as C-Fe. 0.33 -1400.

[0081] Example 4

[0082] The difference between Example 4 and Example 1 is that the amount of hyperbranched PBSZ-SiH polymer used is 12g, while the rest is the same as in Example 1.

[0083] Example 5

[0084] The difference between Example 5 and Example 1 is that the amount of hyperbranched PBSZ-SiH polymer used is 18g, while the rest is the same as in Example 1.

[0085] 1. The SiBCN-Fe ceramic C-Fe prepared in Example 1 of this application 0.33 Morphological characterization was performed at -1300, as detailed below:

[0086] Its SEM, such as Figure 1 As shown. From Figure 1 It can be seen that the FeSi nanoparticles are spherically aggregated at the tip, which is consistent with the catalytic mechanism of "tip growth" and "base growth"; the FeSi nanoparticles are completely encapsulated in the carbon layer, and the carbon layer forms a perfect coating on the FeSi nanoparticles.

[0087] Figure 2 Its TEM and elemental distribution map. From Figure 2 It can be seen that C, N and B elements are evenly distributed around FeSi elements, forming a barrier, which further confirms the successful construction of the core-shell structure.

[0088] Figure 3 Its high-resolution TEM image. From Figure 3 A graphitic carbon layer of approximately 85 nm and an interlayer spacing of approximately 0.33 nm are clearly visible, corresponding to the (002) crystal plane of C. This is attributed to the fact that iron acts as a graphitization catalyst to promote the ordering of the carbon structure, facilitating the transformation of disordered carbon remaining from PBSZ pyrolysis into ordered graphitic carbon (sp). 2 (Structure), and accelerated graphite agglomeration during high-temperature pyrolysis, resulting in a 1D to 2D transformation. The in-situ introduction of Fe into the FeSi phase, encapsulated by the graphite carbon layer, creates a barrier effect. Due to the presence of B and N elements in the material system, from Figure 3 Significant defects can be observed in the carbon layer, and introducing more electric dipoles is beneficial for improving the polarization loss of electromagnetic wave absorbing materials. Furthermore, from... Figure 3 Fe3Si(220) lattice fringes of approximately 0.20 nm and Fe3Si(111) lattice fringes of 0.32 nm can be observed.

[0089] The SiBCN-Fe ceramic C-Fe prepared in Examples 1-3 of this application 0.33 -1300, C-Fe 0.33 -1200 and C-Fe 0.33 XRD tests were performed at -1400°C, and the spectrum is as follows: Figure 4 As shown. From Figure 4 It can be seen that the SiBCN-Fe ceramic exhibits a diffraction peak of graphitic carbon (PDF#98-000-0231) at 2θ=26.1°, and clear lattice fringes are visible. Figure 3The results were confirmed in high-resolution TEM (HRTEM); β-SiC (PDF#01-075-0254) diffraction peaks appeared at 2θ = 35.6°, 41.7°, 59.6°, and 71.4°. This is because iron catalyzes the breaking of Si-N / BN bonds in the polyboron-silicon-carbonazine system, releasing active silicon atoms and forming a eutectic Fe-Si liquid phase with the released silicon at 1200–1300 °C. This significantly reduces the surface tension at the liquid-SiC interface, thus providing a lower energy barrier for SiC nucleation. Figure 4 As can be seen, the FeSi phase is mainly composed of Fe3Si (PDF#04-004-6815), with Fe5Si3 (PDF#97-016-1131) and FeSi (PDF#04-007-2551) as secondary components. Characteristic diffraction peaks for Fe3Si are observed at 2θ = 45.5°, 52.4°, and 84.0°, respectively; for Fe5Si3, a characteristic diffraction peak is observed at 2θ = 47.1°; and for FeSi, characteristic diffraction peaks are observed at 2θ = 50.2° and 79.8°. This is attributed to the reaction between the Si and Fe phases at 1100℃, forming Fe3Si crystals. As the Si and C atoms in the liquid phase become saturated, precipitation and solidification occur to form Fe5Si3.

[0090] SiBCN-Fe ceramic C-Fe prepared in Example 1 0.33 Multiple XRD tests were performed at -1300, and the results are as follows: Figure 5 As shown. From Figure 5 The diffraction rings of SiC(111)(222)(220) can be observed, further proving that Figure 4 The diffraction peaks of β-SiC were observed. Furthermore, a Fe5Si3(211) diffraction ring of approximately 0.19 nm was observed in multiple diffractions, further confirming... Figure 4 The result in the middle.

[0091] The SiBCN-Fe ceramic C-Fe prepared in Examples 1-3 of this application 0.33 -1300, C-Fe 0.33 -1200 and C-Fe 0.33 XPS testing was conducted at -1400, and the spectrum is as follows: Figure 6As shown, the Fe signal can be clearly detected, confirming the successful introduction of Fe. The Fe 2p spectrum can be divided into four peaks, with the strongest peak at 711.4 eV belonging to Fe 2p3 / 2, which also confirms the formation of the FeSi phase. The peaks at 715 eV and 725.3 eV correspond to the satellite peaks of Fe 2p3 / 2 and Fe 2p1 / 2, respectively, and can be attributed to Fe ions in FeSi. The above proves the existence of the FeSi phase. In the Si 2p spectrum, the strongest peak is the Si-C peak at 101.1 eV, and the C-Si peak at 283 eV in the C1s spectrum corroborates the formation of SiC crystals, which is consistent with the XRD and HRTEM results. In addition, the C-C peak at 284.7 eV in the C1s spectrum indicates the presence of a large amount of graphitic carbon. In the N1s and B1s energy spectra, the strongest peaks at 398.7 eV (N 1s) and 191.1 eV (B 1s) are characteristic peaks belonging to the BN bond. Meanwhile, the N1s energy spectrum also shows a small number of CN and Si-N characteristic peaks. Due to unavoidable oxygen interference during sample preservation and testing, a large number of oxygen-related binding energies are visible in the energy spectrum, but these were not found in other characterizations and are therefore not analyzed here.

[0092] The SiBCN-Fe ceramic C-Fe prepared in Examples 1-3 of this application 0.33 -1300, C-Fe 0.33 -1200 and C-Fe 0.33 -1400 Raman spectroscopy was used to characterize the speciation of carbon elements within the ceramic. The test results are as follows: Figure 7 As shown. By Figure 7 It can be seen that C-Fe at different pyrolysis temperatures 0.33 -1200, C-Fe 0.33 -1300 and C-Fe 0.33 The -1400 ceramic material exhibits two significant peaks, the D-band and the G-band, characteristic of carbon graphitization. The ID / IG ratio gradually decreases with increasing pyrolysis temperature, with ratios of 1.221, 1.123, and 1.078, respectively. This is attributed to the enhanced catalytic effect of temperature on iron, inducing the formation of more graphitic carbon. The ID / IG ratios are all greater than 1, attributed to the abundant high-density defects within the ceramic material. These defects contribute to the formation of abundant interfacial polarization, thereby enhancing the dielectric properties of the ceramic material. Furthermore, the π-electron conjugation caused by defects disrupts conductivity, leading to local conductivity gradients that form microscopic current pathways, which can enhance electromagnetic wave loss capability.

[0093] 2. The electromagnetic absorption capacity of the SiBCN-Fe ceramics prepared in Examples 1-3 was evaluated using transmission line theory.

[0094] Figure 8 C-Fe0.33 -1200, C-Fe 0.33 -1300 and C-Fe 0.33 The test results of complex permittivity and complex permeability at -1400 are shown in Figure a, where Figure a represents the test results of complex permittivity and Figure b represents the test results of complex permeability. Figure 8 In this equation, the real part (ε′) of the complex permittivity and the real part (μ′) of the complex permeability represent the electromagnetic energy storage capacity, while the imaginary parts ε″ and μ″ represent the electromagnetic energy loss capacity.

[0095] from Figure 8 As shown in Figure a, the complex permittivity increases with increasing pyrolysis temperature. This is attributed to the enhanced catalytic activity of Fe at higher pyrolysis temperatures, leading to the formation of more ordered carbon and consequently, an increase in conductivity. Specifically, C-Fe... 0.33 -1300 and C-Fe 0.33 The -1400 samples all exhibited high ε” values, stemming from strong polarization relaxation or conductivity loss within the material, such as interfacial polarization or defect-induced dipole redirection. This indicates that the material possesses excellent dielectric loss capability, but C-Fe 0.33 The -1300 sample has a lower ε′ value, thus exhibiting better impedance matching and superior absorption performance. Meanwhile, the C-Fe sample... 0.33 The -1200 sample consistently exhibited an ε″ below 2.0 (minimum 0.75 @ 17.6 GHz), indicating extremely weak loss capability; therefore, C-Fe... 0.33 The -1200 sample exhibits poor absorption capability. In the low-frequency range (2-5 GHz), C-Fe... 0.33 The ε” value at -1300 GHz is greater than ε′, indicating strong dielectric polarization loss, but also resulting in weak absorption at low frequencies due to impedance imbalance. As the ε” value decreases more significantly than the ε′ value, until the high-frequency range (9-18 GHz), a better impedance matching is achieved while maintaining high dielectric loss, resulting in C-Fe... 0.33 The -1300 sample also exhibited excellent microwave absorption capabilities. All samples showed a decreasing trend in complex permittivity with increasing frequency, which is a classical dielectric relaxation polarization response, indicating the existence of multiple polarization mechanisms (such as interfacial polarization or dipole relaxation) in the material.

[0096] from Figure 8As shown in Figure b, the real (μ') and imaginary (μ″) parts of the complex permeability of the three samples are close to 1.0 (0.99–1.38 and 0 (0.01–0.19), respectively, but exhibit significant fluctuations within the test frequency range. This is attributed to the restricted domain wall motion within this frequency range, leading to natural or exchange resonance and resulting in drastic changes in magnetic loss. Furthermore, the eddy current effect is more pronounced within the test frequency range, further introducing fluctuations in the μ″ curve. This indicates that magnetic loss mainly originates from eddy current loss and ferromagnetic resonance. In addition, the interaction between stray magnetic fields and local charge accumulation at the FeSi and carbon layer interface may also contribute to changes in magnetic loss, especially at high frequencies where the interface polarization effect becomes more significant, thus affecting the C-Fe... 0.33 -1200 and C-Fe 0.33 Compared to -1400, C-Fe 0.33 -1300 achieves optimal electromagnetic wave absorption capability. This is attributed to C-Fe 0.33 The balanced complex permittivity and permeability of -1300 ohms mitigate impedance imbalance. Furthermore, the potential difference resulting from the synergistic Fermi level created by the core-shell structure enhances electromagnetic wave coupling, exhibiting a wider electromagnetic wave absorption capability in the 2-18 GHz frequency range, with particularly strong performance at high frequencies. (C-Fe) 0.33 -1300 is the optimal sample, exhibiting excellent absorption intensity and broadband coverage.

[0097] Figure 9 C-Fe 0.33 -1200, C-Fe 0.33 -1300 and C-Fe 0.33 The reflection coefficient test results for -1400 are shown in the image. From... Figure 9 It can be seen that C-Fe 0.33 The -1300 achieves an effective absorption bandwidth of 8.16 GHz with a minimum thickness of 2.7 mm and a peak absorption value below -32.2 dB with a thickness of 2.0 mm. This superior performance highlights its significant absorption capability over the target frequency range. In contrast, C-Fe 0.33 -1200 and C-Fe 0.33 -1400 exhibits relatively weak performance, C-Fe 0.33 -1200 exhibits poor absorption bandwidth at 3.72 GHz at 6.4 mm due to its lack of loss capability; while C-Fe 0.33 -1400 undergoes pyrolysis at higher temperatures, leading to increased loss phases but severe impedance imbalance. This results in an effective absorption bandwidth of 5.28 GHz achieved with a thickness of 1.7 mm, but the lowest reflection loss is only -17.7 GHz @ 1.4 mm.

[0098] In practical applications, it is necessary to calculate the electromagnetic wave dissipation capability under different incident angles. Therefore, we use RCS (Radar Cross Section) simulation to evaluate the radar reflection loss under different incident angles (-90°≥θ≤90°) and assess the actual stealth capability of the sample. We use the time-domain solver in CST to simulate a perfectly conductive (PEC) substrate and an absorbing coating (C-Fe). 0.33 -1200, C-Fe 0.33 -1300 and C-Fe 0.33 RCS simulation was performed at -1400, and the test results are as follows: Figure 10 As shown.

[0099] Figure 10 The results show that the perfectly conductive (PEC) plate coated with SiBCN-Fe ceramic electromagnetic wave absorber exhibits significantly reduced scattered signals compared to a pure PEC plate, confirming that the SiBCN-Fe ceramic electromagnetic wave absorber can effectively absorb a large amount of microwave energy. Among them, C-Fe... 0.33 The -1300 sample exhibits the highest RCS reduction of 18.0 dBm at a 0° incident angle. 2 This is consistent with the reflection loss (RL) results; these results confirm C-Fe 0.33 The -1300 sample can effectively dissipate electromagnetic energy and reduce radar scattering intensity, thus producing excellent electromagnetic wave absorption capability.

[0100] 3. Corrosion resistance tests were performed on the SiBCN-Fe ceramics prepared in Examples 1-3 of this application.

[0101] The specific test method is as follows: Evaluation is performed using a three-electrode system in a 3.5 wt% NaCl solution, with carbonyl iron (CIP) as the control sample. The test results are as follows: Figure 11 As shown. Among them, Figure 11 Figure a is the OCP plot, figure b is the Tafel plot, figure c is the Nyquist plot, and figure d is the Bode phase angle-frequency plot.

[0102] Figure 11 In Figure a, the open-circuit voltage (OCP) reflects the spontaneous potential of the material in the corrosive medium. A higher OCP value indicates a lower corrosion tendency, C-Fe 0.33 The -1300 sample had a corrected OCP value, demonstrating that it had the lowest tendency for spontaneous corrosion.

[0103] Figure 11 In Figure b, the Tafel polarization curves can assess the corrosion potential (Ecorr) and corrosion current density (Icorr) of a material, reflecting the initiation and rate of corrosion, respectively. Materials with high corrosion potential and low corrosion current density are considered excellent corrosion-resistant materials. Compared with other samples, C-Fe 0.33The -1300 sample exhibited the highest Ecorr (0.033 V) and the lowest Icorr (0.6295 μA / cm). 2 The results indicate that the corrosion kinetics of SiBCN-Fe ceramics are significantly reduced, and the protective barrier formed by the construction of the core-shell structure enhances the corrosion resistance of the sample.

[0104] Figure 11 Figure c is a Nyquist plot obtained after immersing the sample in a neutral salt solution for 1600 seconds, where C-Fe can be observed. 0.33 The impedance arc radius of the -1300 sample is significantly larger than that of other electrodes, indicating that it has a lower current-carrying capacity and a higher resistance in charge transport.

[0105] To further analyze the barrier effect of the material in a corrosive environment, its Bode phase angle-frequency diagram was analyzed, and the results are as follows: Figure 11 As shown in Figure d, the impedance value at 0.01 Hz (|Z|0.01 Hz) is a semi-quantitative parameter for evaluating corrosion resistance. The SiBCN-Fe ceramic of this application exhibits significantly higher impedance and phase angle across the entire frequency range, indicating superior corrosion resistance.

[0106] Although this application has been described in detail in this specification with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, such modifications or improvements made without departing from the spirit of this application are all within the scope of protection claimed in this application.

Claims

1. A preparation method of SiBCN-Fe ceramic corrosion-resistant wave-absorbing material, characterized in that, The preparation method comprises the following steps: S1, under an argon atmosphere, carrying out a hydroboration reaction of dichloromethylvinylsilane and borane-dimethyl sulfide complex to obtain tris(dichloromethylsilyl ethyl)borane; carrying out a polycondensation reaction of tris(dichloromethylsilyl ethyl)borane, dichloromethylsilane and hexamethyldisilazane to obtain a crude product; and carrying out purification and cooling on the crude product to obtain a hyperbranched PBSZ-SiH polymer; S2, under an argon atmosphere, dissolving acetylacetone iron in anhydrous xylene, and then adding the hyperbranched PBSZ-SiH polymer to carry out a reaction; collecting a solid phase to obtain a PBSZ-Fe ceramic precursor; S3, carrying out a cross-linking reaction on the PBSZ-Fe ceramic precursor by heating; grinding the product after the cross-linking reaction into a powder, and then carrying out a high-temperature pyrolysis under an argon atmosphere to obtain a SiBCN-Fe ceramic.

2. The production method according to claim 1, characterized by, The temperature of the hydroboration reaction is -78-25 ℃, and the time is 5-24 h. The temperature of the polycondensation reaction is -78-25 ℃, and the time is 2-6 h. The purification specifically comprises volatilizing and removing unreacted monomers and by-products by heating the crude product to 25-220 ℃.

3. The preparation method according to claim 1, characterized in that, In S1, the molar ratio of dichloromethylvinylsilane, borane-dimethyl sulfide complex and dichloromethylsilane is 3:1:1, and the amount of hexamethyldisilazane is excessive.

4. The method of claim 1, wherein, In S2, the mass ratio of acetylacetone iron to the hyperbranched PBSZ-SiH polymer is 1:1-3.

5. The preparation method according to claim 1, characterized in that, The temperature of the reaction in S2 is 25-180 ℃, and the time is 6-72 h.

6. The method of claim 1, wherein, The heating rate of the heating in S3 is 1-10 ℃ / min. The temperature of the cross-linking reaction is 250-550 ℃, and the time is 0.5-3 h.

7. The preparation method according to claim 1, characterized in that, The particle size of the powder in S3 is less than 400 mesh.

8. The method of claim 1, wherein, The temperature of the high-temperature pyrolysis in S3 is 1100-1500 ℃, and the holding time is 2-5 h.

9. The SiBCN-Fe ceramic corrosion-resistant wave-absorbing material prepared by the preparation method in any one of claims 1-8.

10. Application of the SiBCN-Fe ceramic corrosion-resistant wave-absorbing material in claim 9 as a ship wave-absorbing material in a marine environment.

Images