High-performance conductive foam and preparation method thereof

Abstract

The present application relates to a kind of high-performance conductive foam and its preparation method, with end vinyl polyorganosilicon and platinum gold sulfurizing agent, silane coupling modified C / NiFe composite aerogel powder, crosslinking inhibitor and silicone surfactant are dispersed into first mixed material under dry and vacuum shear;With hydrogen-containing polysiloxane as Si-H hydrogen-donating source, cooperate end vinyl polyorganosilicon, hydroxyl-terminated polysiloxane and water to form second mixed material;Two materials are compounded, defoaming after injection molding, pre-curing forms stable cell, after curing completes addition crosslinking and chemical foaming synergistic molding, and foam body is obtained;After heat treatment, the size and electrical properties are stable, and conductive layer is laminated on one side, and adhesive layer and isolation layer are set on the other side.Product has high conductivity / high shielding, heat resistance, salt fog resistance and excellent resilience, and is suitable for thin electronic equipment EMI sealing and cushion assembly.

Description

Technical Field

[0001] This invention relates to the field of conductive foam, and particularly to high-performance conductive foam and its preparation method. Background Technology

[0002] With the rapid development of 5G / millimeter-wave communication, automotive electronics, industrial control, and high-density packaging, electronic devices are operating in higher frequency and more complex electromagnetic environments, placing comprehensive demands on shielding materials that are "lightweight, thin, compressible, environmentally resistant, and long-term stable." Traditional solutions, represented by metal foil, conductive fabrics, and conductive foam, have certain advantages in terms of assembly tolerance compensation, springback, and cost, but they still have significant shortcomings in terms of thinness and stable shielding across a wide frequency band (especially at the GHz level).

[0003] Aerogel materials, with their ultra-high porosity, interconnected three-dimensional framework, and extremely low density, are considered ideal substrates for achieving electromagnetic dissipation through "long-path, multi-interface, and multiple scattering." Their pore walls can be functionalized to introduce conductive or dielectric / magnetic components, thereby establishing effective charge transport and polarization loss pathways with relatively low filler content. Simultaneously, the three-dimensional network exhibits structural tolerance under compression deformation, helping to maintain mechanical resilience and conductive continuity. Thermally, carbon-based or inorganic aerogels possess higher upper temperature limits and morphological stability compared to conventional polymer matrices, providing potential support for the long-term service of thin-layer shielding materials. These characteristics demonstrate the application potential of aerogels in thinner, lighter, and absorptive shielding.

[0004] However, existing conductive foam products have revealed a series of common problems in actual service: First, in environments containing chlorine or weak acids such as salt spray and sweat, the metal conductive layer is prone to corrosion and interface degradation, leading to increased contact resistance and fluctuating shielding effectiveness over time, manifesting as poor salt spray resistance and unstable conductivity. Second, obtaining a through-conductive network often requires higher filler or thicker plating, resulting in partial blockage of pores, increased density, and increased compression set, which is particularly noticeable in thinner sizes, directly limiting the ability to make them even thinner. Third, the substrate material is prone to aging, softening, or pulverizing during thermal / humidity cycling, resulting in decreased interfacial adhesion and insufficient heat resistance and thermal aging stability. Fourth, the shielding mechanism is mainly based on surface reflection, with limited absorption contribution; impedance mismatch becomes more prominent after thinning, leading to unsatisfactory electromagnetic shielding effects, especially in the GHz band. The combination of these problems has become a major obstacle to the high-reliability application of thin conductive foam products.

[0005] Against this backdrop, the key technical challenges faced by the industry are not simply improving single material properties, but rather achieving a comprehensive balance among multiple factors: First, how to maintain continuous and low-resistance conductive channels and pore connectivity / rebound within extremely thin thicknesses, avoiding fluctuations in electromechanical coupling caused by increased percolation thresholds and deformation; second, how to maintain uniform synergy among conductive, dielectric, and potentially magnetic loss components at the micro-nano scale, reducing agglomeration and interface loosening, and preventing intermittent network failures under salt spray, humid heat, and cyclic compression conditions; third, the surface chemistry, dispersion stability, and forming / curing processes (including crosslinking and foaming) of the material need to be matched, neither damaging the pore structure nor inhibiting matrix curing, thus reducing batch dispersion and long-term drift; finally, quality control and process windows for large-scale applications need to be clear and reusable, ensuring that the trade-offs between thickness, pore structure, conductive paths, and environmental tolerance can be reliably reproduced. Overall, establishing a replicable engineering balance between thinness, broadband efficiency, and environmental tolerance, and solidifying it into stable manufacturing capabilities, is a common technical problem that urgently needs to be solved in the field of electromagnetic shielding elastomer materials. Summary of the Invention

[0006] In view of the above analysis, the present invention aims to provide a high-performance conductive foam and its preparation method to solve the problems in the background art.

[0007] The present invention provides a method for preparing high-performance conductive foam in a first aspect, comprising the following steps:

[0008] S10: Prepare the first mixture by using vinyl-terminated polysilicon as the matrix, and mixing it with a platinum vulcanizing agent, C / NiFe composite functional aerogel powder modified with a silane coupling agent, a crosslinking inhibitor, and an organosilicon surfactant under drying and vacuum shear dispersion conditions to obtain a uniformly dispersed first mixture; wherein, the C / NiFe composite functional aerogel powder is a composite particle formed by loading ferrite in situ onto a carbon aerogel skeleton and then electroless nickel plating and annealing, and its surface has a silane coupling layer containing amino and / or vinyl groups;

[0009] S20: Prepare a second mixture by using hydrogen-containing polysiloxane as the hydrogen source for Si–H crosslinking and chemical foaming, matching its viscosity and rheology with vinyl-terminated polysiloxane, and introducing hydroxyl-terminated polysiloxane and water or an aqueous system as a chemical foaming promoting system, and mixing them evenly to obtain the second mixture.

[0010] S30: The first mixture and the second mixture are compounded, and the mixture is then mixed and degassed under vacuum to obtain a foaming reaction material;

[0011] S40: The foaming reactant is injected into the mold to form a stable cell structure under pre-curing conditions, and then undergoes addition cross-linking and chemical foaming synergistic molding under post-curing conditions to obtain a silicone conductive foam preform.

[0012] S50: The foam preform is subjected to heat treatment, and a conductive layer is provided on one side of the foam. The conductive layer is any one or a combination of metallized conductive cloth, metal mesh, metal foil or conductive coating layer, and / or an adhesive layer and an isolation layer are provided on the other side.

[0013] In one or more preferred embodiments, step S10 specifically involves using 100 parts of vinyl-terminated polydimethylsiloxane as a matrix, adding 0.2–2.0 parts of platinum vulcanizing agent, 8–22 parts of C / NiFe composite functional aerogel powder, and adding 0.05–0.15 parts of crosslinking inhibitor 2-methyl-3-butyn-2-ol and 0.2–1.0 parts of organosilicon surfactant polydimethylsiloxane copolyol; dispersing the mixture under a vacuum of 0.05–0.08 MPa at 800–1500 r / min for 1–3 min to obtain a first mixture, and vacuum drying at 110–120 °C for 1–2 h before adding the first mixture.

[0014] In one or more preferred embodiments, the preparation method of the C / NiFe composite functional aerogel powder is as follows:

[0015] S1: Take 2-4 parts by weight of resorcinol and 3-6 parts by weight of formaldehyde and add them to 40-80 parts by weight of deionized water. Add 0.02-0.10 parts by weight of sodium carbonate to make the system weakly alkaline. Gel at 25-35℃ and age for 6-24 hours. Then replace with anhydrous ethanol or acetone 3-5 times and dry at 40-60℃ for 8-16 hours to obtain RF dry gel.

[0016] S2: Under nitrogen atmosphere, at 2-5℃·min -1 The RF dry gel was heated to 800-1000℃ and held for 1-3 hours to complete the carbonization. The resulting carbon aerogel was pulverized and classified to make the particle size D50=50-120μm and D90≤180μm.

[0017] S3: Using an ethylene glycol / water mixed solvent, disperse 10 parts of carbon aerogel particles, add 1.0-2.5 parts of ferric chloride and 0.3-1.2 parts of ferrous sulfate, adjust the pH to 9-11 with ammonia water, react at 60-90℃ for 30-90 min and mature, then wash and dry at 60-80℃ for 1-3 h to obtain C@Fe3O4;

[0018] S4: Take 10 parts of C@Fe3O4 composite particles and place them in a system consisting of 50-100 parts of sensitizing solution, wherein the sensitizing solution is a 0.1-1.0wt% hydrochloric acid aqueous solution containing 0.05-0.20 parts of stannous chloride, and immerse for 5-15 minutes;

[0019] The sensitized particles were transferred into a system consisting of 50-100 parts of an activation solution containing 0.001-0.010 parts of palladium chloride. The activation solution was adjusted to pH 1-2 with hydrochloric acid, and the particles were soaked for 5-15 minutes before being removed and rinsed with deionized water until pH 6-7.

[0020] Ten parts of activated particles are added to 100-200 parts of a chemical plating solution for electroless nickel plating. The chemical plating solution consists of 1.0-5.0 parts of nickel sulfate as the main salt, 0.3-1.5 parts of sodium hypophosphite as the reducing agent, and 0.5-2.0 parts of a complexing agent and a buffer system. During plating, the pH is adjusted to 8.5-10.0 with ammonia water, and the reaction is carried out at 60-85℃ for 10-40 minutes. After plating, the solution is annealed at 300-400℃ in nitrogen for 0.5-2 hours. The complexing agent is sodium citrate and / or lactic acid.

[0021] S5: Take 10 parts of C / NiFe composite aerogel particles, add them to 50-100 parts of anhydrous ethanol or toluene, add 0.5-2.0 parts of silane coupling agent, react at 40-60℃ for 1-3 hours, wash with anhydrous ethanol 2-3 times and vacuum dry at 80℃ for 1-3 hours to complete surface modification; the silane coupling agent is APTES and / or VTMS.

[0022] In one or more preferred embodiments, step S20 specifically involves using 15–30 parts of hydrogen-containing silicone oil as the hydrogen source for crosslinking and foaming, combined with 70–100 parts of vinyl-terminated polydimethylsiloxane for viscosity matching, and adding 1.0–5.0 parts of hydroxyl-terminated polysiloxane and 0.05–0.30 parts of deionized water as a chemical foaming promoting system, and stirring evenly to obtain a second mixture.

[0023] In one or more preferred embodiments, step S30 specifically involves mixing the first mixture and the second mixture at a mass ratio of 1:(1.0–1.2), mixing at 25–35°C for 2–5 min, and degassing under a vacuum of 0.05–0.08 MPa for 1–3 min to obtain a foaming reaction material.

[0024] In one or more preferred embodiments, step S40 specifically involves injecting the foaming reactant into a mold, pre-curing it at 80–100°C for 10–20 min to form stable cells, and then curing it at 120–150°C for 30–60 min to complete cross-linking and molding, thereby obtaining a silicone conductive foam preform.

[0025] In one or more preferred embodiments, step S50 specifically involves heat-treating the foam preform at 150–180°C for 1–2 hours; providing a conductive cloth, which is a nickel-plated copper conductive cloth, on one side of the foam and hot-pressing it at 120–140°C and 5–6 MPa for 10–15 minutes; and providing an adhesive layer of acrylic pressure-sensitive adhesive on the other side and covering it with a 0.02–0.03 mm polyethylene release film.

[0026] In one or more preferred embodiments, the thickness of the electrical cloth is 0.03–0.05 mm.

[0027] In one or more preferred embodiments, the acrylic pressure-sensitive adhesive coating thickness is 0.05–0.06 mm.

[0028] In a second aspect, the present invention provides a high-performance conductive foam, which is prepared by the above-described method.

[0029] The principle of this invention:

[0030] 1. Synergistic optimization of conductivity and electromagnetic shielding effectiveness

[0031] This invention employs C / NiFe composite functional aerogel powder. The nickel particles, Fe3O4 magnetic oxide, and carbon aerogel framework of this composite filler work synergistically to significantly improve the electromagnetic shielding effectiveness of the material while maintaining electrical conductivity. The nickel particles provide the basic conductive path, and the nickel plating forms a continuous and stable conductive network within the conductive foam. However, the conductivity of nickel alone is far from sufficient, especially in high-frequency electromagnetic environments, where traditional conductive fillers often fail or degrade. The magnetic properties of Fe3O4 are enhanced through its electronic transitions (Fe³⁺... + ↔Fe² + It absorbs high-frequency electromagnetic waves and converts them into heat energy, thereby effectively reducing the intensity of electromagnetic waves. Furthermore, the particle scattering effect of Fe3O4 causes electromagnetic waves to be absorbed, scattered, and attenuated multiple times within the foam, ultimately improving the electromagnetic shielding effectiveness. This synergistic effect not only complements conductivity but also forms a multi-layered shielding mechanism in terms of electromagnetic shielding effectiveness.

[0032] The carbon aerogel framework, with its high specific surface area and porous structure, provides a stable support structure for nickel and Fe3O4. Carbon aerogel not only enhances the stability of the conductive path, making the conductive network less prone to breakage under external pressure or deformation, but its thermal stability also helps maintain the conductivity of the foam under high temperatures and external environmental stress. These synergistic effects ensure that the material maintains excellent electrical conductivity and electromagnetic shielding performance even in ultra-thin dimensions (≤0.6 mm) in complex environments.

[0033] 2. Synergistic improvement in thermal stability and anti-aging ability

[0034] The synergistic effect of Fe3O4 and the nickel plating not only improves the thermal stability of the foam but also enhances its anti-aging properties. The high-temperature stability of Fe3O4 effectively prevents oxidation in high-temperature environments, avoiding common metal oxidation problems, especially the oxidation reactions of nickel and iron oxides. Simultaneously, the particle scattering effect of Fe3O4 effectively disperses the heat generated by electromagnetic wave absorption, preventing localized overheating. This is achieved through the electronic transitions of Fe3O4 particles (Fe³⁺... + ↔Fe² + Electromagnetic energy is converted into heat energy and the heat is evenly distributed through a particle scattering mechanism, ensuring a uniform temperature within the material and reducing the risk of heat accumulation. This heat dispersion characteristic enhances the thermal stability of the foam and effectively prevents the formation of high-temperature zones, thus ensuring the stability, conductivity, and electromagnetic shielding effectiveness of the material during long-term use and in high-temperature environments. The nickel plating, as an effective oxidation barrier, prevents oxygen and moisture intrusion, further protecting the conductive paths from corrosion. The combined effect of nickel's oxidation resistance and Fe3O4's thermal stability allows the foam to operate stably for extended periods in high-temperature environments without losing its conductivity and electromagnetic shielding effects. A key aspect of this synergistic effect is that Fe3O4, through its excellent chemical stability, especially at high temperatures, can inhibit the oxidation reaction of metal particles by limiting the diffusion of oxidation. The nickel plating, acting as an internal and external barrier, isolates external oxygen, ensuring the long-term stability of the foam under high-temperature conditions. The synergistic effect of these two elements enhances the high-temperature resistance of the foam, enabling it to maintain excellent electrical conductivity and electromagnetic shielding effectiveness even during long-term high-temperature exposure.

[0035] 3. Synergistic enhancement of mechanical properties and conductive network stability

[0036] The synergistic effect of the carbon aerogel framework, Fe3O4, and nickel plating plays a crucial role in improving mechanical properties and the stability of the conductive network, especially under long-term use and high-stress environments, where the material's stability is greatly enhanced. The porous structure of the carbon aerogel framework not only improves the material's toughness but also strengthens the foam's compressive strength. Its thermal stability prevents deformation or conductive path breakage due to external forces or temperature changes during long-term use. Furthermore, the particle scattering effect of Fe3O4 and the conductivity of nickel synergistically enhance the continuity of the conductive path during long-term use. Especially under dynamic loads and prolonged repeated compression, the material maintains its conductivity and electromagnetic shielding effectiveness, without exhibiting conductive network breakage or electrical performance degradation.

[0037] The conductivity of nickel and the stability of Fe3O4 work synergistically within the conductive network to ensure the durability and long-term stability of the conductive foam. This material maintains excellent electrical properties even in harsh environments, preventing the conductive network from breaking due to external forces or environmental stress.

[0038] 4. Synergistic improvement in salt spray resistance and corrosion resistance

[0039] This invention significantly improves the salt spray resistance and corrosion resistance of foam through the interaction of the carbon aerogel framework, Fe3O4, and nickel plating. The hydrophobicity of the silica matrix and the physical barrier formed by its dense cross-linked structure significantly reduce the penetration of chloride ions and moisture in the salt spray, thus reducing corrosion. The passivation film (Ni–P / partial NiO) of the nickel plating, formed through annealing, enhances the corrosion resistance of nickel, especially maintaining stability in chlorinated media. The nickel plating prevents metal oxidation while also isolating chloride ion penetration from the salt spray, further improving the corrosion resistance of the foam.

[0040] The spinel structure of Fe3O4 exhibits extremely strong chemical stability. In salt spray environments, Fe3O4 can inhibit further oxidation and effectively prevent the propagation of pitting corrosion. This effect is particularly important for the long-term use of materials, especially in marine climates or industrial environments where salt spray corrosion can lead to a decline in the electrical conductivity of traditional metal fillers.

[0041] Surface modification with silane coupling agents (such as APTES / VTMS) forms Si–O–Si bond bridges, reducing ion enrichment at the interface in salt spray, preventing interface delamination, and effectively improving the interfacial bonding and corrosion resistance of the material.

[0042] This allows the material to maintain low resistance drift and stable electromagnetic shielding performance even after salt spray exposure, avoiding the conductive network breakage and electromagnetic shielding performance degradation caused by corrosion products common in traditional metal powder and carbon filler systems.

[0043] Compared with the prior art, the present invention has at least the following beneficial effects:

[0044] (1) The present invention is based on a composite structure of “carbon aerogel three-dimensional framework - in-situ magnetic Fe3O4 - chemically plated Ni / Ni3P and annealed”: the carbon framework provides a through-path and a low percolation threshold, Fe3O4 introduces magnetic / dielectric loss and improves impedance matching, and Ni / Ni3P forms a continuous conductive phase and enhances high-frequency reflection. The three work together to enable the material to have low resistance, wide-band shielding and less thickness dependence at a relatively thin thickness, solving the problems of “difficult conduction, poor matching and easy reliance on thickness to improve performance” of thin-gauge shielding materials.

[0045] (2) Stabilization design, taking into account heat resistance, damp heat and cycling, Ni / Ni3P annealing densification and passivation inhibit oxygen / water intrusion, supplemented by in-plane thermal conductivity of carbon skeleton and thermal diffusion points of Fe3O4, reducing the risk of microcracks and network breakage under thermal coupling; at the same time, stress and current concentration are dispersed by multi-scattering structure. As a result, it can maintain stable conductivity and shielding performance after thermal aging, damp heat / salt spray and repeated compression, solving the reliability shortcomings of traditional conductive foam such as "resistance rise and performance decay".

[0046] (3) Performance and resilience are simultaneously controllable. Solvent replacement and gentle drying are used to preserve pores. In-situ co-precipitation achieves "anchored" loading of Fe3O4. Sensitization / activation-chemical plating combined with silane coupling such as APTES / VTMS constructs a robust inorganic / organic interface and avoids filler clogging. The particle size, loading and coating thickness of this route can be controlled in the process, ensuring both the consistency of conductivity / shielding and maintaining good resilience and dimensional stability.

[0047] (4) Advantages of green environmental protection and sustainability: This invention uses fluorine-free materials, avoiding the use of toxic fluorides, which is in line with the concept of green environmental protection. C / NiFe composite functional aerogel powder, as a green conductive filler, has a low production cost and is recyclable. While ensuring good electromagnetic shielding and conductivity, it reduces the environmental burden during the production process. In addition, the fluorine-free process in the entire preparation process not only reduces environmental pollution but also enhances the potential for sustainable development, meeting the dual requirements of modern industry for environmental protection and economic benefits.

[0048] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0049] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0050] Figure 1 This is a schematic diagram of the preparation method of the high-performance conductive foam of the present invention. Detailed Implementation

[0051] The technical solution of the present invention will be further described below with reference to specific embodiments. However, the present invention should not be limited to these embodiments. Unless specifically stated otherwise, all features can be replaced by other equivalent or similar features. Unless specifically stated otherwise, each feature is only one example of a series of equivalent or similar features. The terminology used in the present invention, unless otherwise stated, generally has the meaning commonly understood by those skilled in the art. In the following embodiments, unless otherwise stated, concentration % refers to mass percentage; all substances used are commercially available.

[0052] The reagents used in this embodiment and comparative example are as follows. Those skilled in the art can choose appropriate reagents to replace them, and the effects of the present invention can also be achieved. The following reagent selection is not intended to limit the present invention.

[0053] Vinyl-terminated polydimethylsiloxane was purchased from Hubei Zhonglong Kangcheng Fine Chemical Co., Ltd., CAS No.: 68083-19-2, purity 99%, molecular weight (MW) 28,000, monomer molecular weight: 186.399 g / mol.

[0054] Hydroxyl-terminated polysiloxane, specifically hydroxyl-terminated polydimethylsiloxane, was purchased from Jinan Longcheng Organosilicon Co., Ltd. CAS No. 63148-60-7, purity 99.99%, number-average molecular weight approximately 5000 g / mol, hydroxyl value 45 mg KOH / g.

[0055] The polydimethylsiloxane copolyol was purchased from Dow Corning under the trade name OFX-0193 FLUID. The raw material was PEG-12 polydimethylsiloxane, with CAS number 68937-54-2.

[0056] The platinum catalyst used is Karstedt catalyst, CAS number 68478-92-2.

[0057] The nickel-plated copper conductive cloth was purchased from Suzhou Simiyang Electronic Materials Co., Ltd., product brand: smy005.

[0058] The acrylic pressure-sensitive adhesive was purchased from Henkel Adhesives, product model: IPG Acrylic PSA Tape series.

[0059] The polyethylene separator film is made of HDPE / LDPE film from Changzhou Kaide New Material Co., Ltd.

[0060] Example 1

[0061] Preparation method of C / NiFe composite functional aerogel powder:

[0062] S1: Take 2 parts by weight of resorcinol and 3 parts by weight of formaldehyde and add them to 40 parts by weight of deionized water. Add 0.02 parts by weight of sodium carbonate to make the system weakly alkaline. Gel at 25°C and age for 6 hours. Then replace with anhydrous ethanol 3 times and dry at 40°C for 8 hours to obtain RF dry gel.

[0063] S2: under nitrogen atmosphere at 2℃·min -1 The RF dry gel was heated to 800℃ and held for 1 hour to complete the carbonization. The resulting carbon aerogel was pulverized and classified to make the particle size D50=50μm and D90≤180μm.

[0064] S3: Ten parts of carbon aerogel particles were dispersed in an ethylene glycol / water mixed solvent, and 1.17 parts of FeCl3·6H2O and 0.6 parts of FeSO4·7H2O were added. The pH was adjusted to 9 with ammonia water, and the mixture was reacted at 60℃ for 30 min and matured. After washing and drying at 60℃ for 1 h, C@Fe3O4 was obtained.

[0065] S4: Take 10 parts of C@Fe3O4 composite particles and place them in a system consisting of 50 parts of sensitizing solution, wherein the sensitizing solution is a 0.1wt% hydrochloric acid aqueous solution containing 0.05 parts of stannous chloride, and immerse for 5 minutes.

[0066] The sensitized particles were transferred into a system consisting of 50 parts of an activation solution containing 0.001 parts of palladium chloride. The activation solution was adjusted to pH=1 with hydrochloric acid, and the particles were soaked for 5 minutes before being removed and rinsed with deionized water until pH=6.

[0067] Ten parts of activated particles were added to 100 parts of a chemical plating solution for electroless nickel plating. The chemical plating solution consisted of 1.0 part nickel sulfate as the main salt, 0.3 parts sodium hypophosphite as the reducing agent, 0.5 parts complexing agent, and a buffer system. During plating, the pH was adjusted to 8.5 with ammonia water, and the reaction was carried out at 60°C for 10 minutes. After plating, the solution was annealed at 300°C for 0.5 hours in nitrogen. The complexing agent was sodium citrate.

[0068] S5: Take 10 parts of C / NiFe composite aerogel particles, add them to 50 parts of anhydrous ethanol, add 0.5 parts of silane coupling agent, react at 40℃ for 1 hour, wash twice with anhydrous ethanol, and vacuum dry at 80℃ for 1 hour to complete surface modification. The silane coupling agent is APTES.

[0069] Prepare silicone conductive foam.

[0070] S10: Using 100 parts of vinyl-terminated polydimethylsiloxane as the matrix, add 0.2 parts of platinum vulcanizing agent, add 8 parts of surface-modified C / NiFe composite functional aerogel powder, and add 0.05 parts of crosslinking inhibitor 2-methyl-3-butyn-2-ol and 0.2 parts of organosilicon surfactant polydimethylsiloxane copolyol; disperse at 800 r / min for 1 min under 0.05 MPa vacuum to obtain the first mixture, and vacuum dry at 110℃ for 1 h before adding the other materials.

[0071] S20: 15 parts of hydrogen-containing silicone oil PMHS are used as the hydrogen source for crosslinking and foaming, 70 parts of vinyl-terminated polydimethylsiloxane are used for viscosity matching, 1.0 part of hydroxyl-terminated polysiloxane and 0.05 parts of deionized water are added as a chemical foaming promotion system, and the mixture is stirred evenly to obtain the second mixture.

[0072] S30: Mix the first mixture and the second mixture at a mass ratio of 1:(1.0), mix at 25°C for 2 min, and degas under 0.05MPa vacuum for 1 min to obtain the foaming reaction material.

[0073] S40: The foaming reactant is injected into the mold and pre-cured at 80°C for 10 minutes to form stable cells, and then cured at 120°C for 30 minutes to complete the cross-linking molding and obtain a silicone conductive foam preform.

[0074] S50: The foam preform is heat-treated at 165°C for 1.5 hours to stabilize its dimensions and electrical properties; a conductive cloth is provided on one side of the foam, the conductive cloth being nickel-plated copper conductive cloth (thickness 0.04 mm), and hot-pressed at 130°C and 5.5 MPa for 12 minutes to bond it; an adhesive layer of acrylic pressure-sensitive adhesive (coating thickness 0.055 mm) is provided on the other side and covered with a 0.025 mm polyethylene release film.

[0075] Example 2

[0076] Preparation method of C / NiFe composite functional aerogel powder:

[0077] S1: Add 4 parts by weight of resorcinol and 6 parts by weight of formaldehyde to 80 parts by weight of deionized water, add 0.10 parts by weight of sodium carbonate to make the system weakly alkaline, gel at 35°C and age for 24 h; then replace with acetone 5 times and dry at 60°C for 16 h to obtain RF dry gel.

[0078] S2: Under nitrogen atmosphere, at 5℃·min -1 The RF dry gel was heated to 1000℃ and held for 3 hours to complete the carbonization. The resulting carbon aerogel was pulverized and classified to make the particle size D50=120μm and D90≤180μm.

[0079] S3: Ten parts of carbon aerogel particles were dispersed in an ethylene glycol / water mixed solvent, and 1.17 parts of FeCl3·6H2O and 0.6 parts of FeSO4·7H2O were added. The pH was adjusted to 11 with ammonia water, and the mixture was reacted at 90℃ for 90 min and matured. After washing and drying at 80℃ for 3 h, C@Fe3O4 was obtained.

[0080] S4: Take 10 parts of C@Fe3O4 composite particles and place them in a system consisting of 100 parts of sensitizing solution, wherein the sensitizing solution is a 1.0wt% hydrochloric acid aqueous solution containing 0.20 parts of stannous chloride, and immerse for 15 minutes.

[0081] The sensitized particles were transferred into a system consisting of 100 parts of an activation solution containing 0.010 parts of palladium chloride. The activation solution was adjusted to pH 2 with hydrochloric acid, and the particles were soaked for 15 minutes before being removed and rinsed with deionized water until pH 7 was reached.

[0082] Ten parts of activated particles were added to 200 parts of a chemical plating solution for electroless nickel plating. The chemical plating solution consisted of 5.0 parts nickel sulfate as the main salt, 1.5 parts sodium hypophosphite as the reducing agent, 2.0 parts complexing agent, and a buffer system. During plating, the pH was adjusted to 10.0 with ammonia water, and the reaction was carried out at 85°C for 40 minutes. After plating, the solution was annealed at 400°C for 2 hours in nitrogen. The complexing agent was lactic acid.

[0083] S5: Take 10 parts of C / NiFe composite aerogel particles, add them to 100 parts of anhydrous toluene, add 2.0 parts of silane coupling agent, react at 60℃ for 3 hours, wash three times with anhydrous ethanol, and vacuum dry at 80℃ for 3 hours to complete surface modification. The silane coupling agent is VTMS.

[0084] Prepare silicone conductive foam.

[0085] S10: Using 100 parts of vinyl-terminated polydimethylsiloxane as the matrix, add 2.0 parts of platinum vulcanizing agent, add 22 parts of surface-modified C / NiFe composite functional aerogel powder, and add 0.15 parts of crosslinking inhibitor 2-methyl-3-butyn-2-ol and 1.0 parts of organosilicon surfactant polydimethylsiloxane copolyol; disperse at 1500 r / min for 3 min under 0.08 MPa vacuum to obtain the first mixture, and vacuum dry at 120℃ for 2 h before adding the other materials.

[0086] S20: 30 parts of hydrogen-containing silicone oil PMHS are used as the hydrogen source for crosslinking and foaming, 100 parts of vinyl-terminated polydimethylsiloxane are added for viscosity matching, 5.0 parts of hydroxyl-terminated polysiloxane and 0.30 parts of deionized water are added as a chemical foaming promotion system, and the mixture is stirred evenly to obtain the second mixture.

[0087] S30: Mix the first mixture and the second mixture at a mass ratio of 1:(1.2), mix at 35°C for 5 min, and degas under a vacuum of 0.08 MPa for 3 min to obtain the foaming reaction material.

[0088] S40: The foaming reactant is injected into the mold and pre-cured at 100°C for 20 minutes to form stable cells. Then, it is post-cured at 150°C for 60 minutes to complete the cross-linking molding and obtain a silicone conductive foam preform.

[0089] S50: The foam preform is heat-treated at 165°C for 1.5 hours to stabilize its dimensions and electrical properties; a conductive cloth is provided on one side of the foam, the conductive cloth being nickel-plated copper conductive cloth (thickness 0.04 mm), and hot-pressed at 130°C and 5.5 MPa for 12 minutes to bond it; an adhesive layer of acrylic pressure-sensitive adhesive (coating thickness 0.055 mm) is provided on the other side and covered with a 0.025 mm polyethylene release film.

[0090] Example 3

[0091] Preparation method of C / NiFe composite functional aerogel powder:

[0092] S1: Take 3 parts by weight of resorcinol and 6 parts by weight of formaldehyde and add them to 60 parts by weight of deionized water. Add 0.06 parts by weight of sodium carbonate to make the system weakly alkaline. Gel at 30°C and age for 12 hours. Then replace with anhydrous ethanol 4 times and dry at 50°C for 12 hours to obtain RF dry gel.

[0093] S2: Under nitrogen atmosphere, at 3℃·min -1 The RF dry gel was heated to 900℃ and held for 2 hours to complete the carbonization. The resulting carbon aerogel was pulverized and classified to make the particle size D50=80μm and D90≤180μm.

[0094] S3: Ten parts of carbon aerogel particles were dispersed in an ethylene glycol / water mixed solvent, and 1.17 parts of FeCl3·6H2O and 0.6 parts of FeSO4·7H2O were added. The pH was adjusted to 10 with ammonia water, and the mixture was reacted at 80℃ for 60 min and matured. After washing and drying at 70℃ for 2 h, C@Fe3O4 was obtained.

[0095] S4: Take 10 parts of C@Fe3O4 composite particles and place them in a system consisting of 80 parts of sensitizing solution, wherein the sensitizing solution is a 0.5wt% hydrochloric acid aqueous solution containing 0.10 parts of stannous chloride, and immerse for 10 minutes.

[0096] The sensitized particles were transferred into a system consisting of 80 parts of an activation solution containing 0.003 parts of palladium chloride. The activation solution was adjusted to pH 1.5 with hydrochloric acid, and the particles were soaked for 10 minutes before being removed and rinsed with deionized water until pH 6.5 was reached.

[0097] Ten parts of activated particles were added to 150 parts of a chemical plating solution for electroless nickel plating. The chemical plating solution consisted of 3.0 parts nickel sulfate as the main salt, 0.8 parts sodium hypophosphite as the reducing agent, 1.0 part a complexing agent, and a buffer system. During plating, the pH was adjusted to 9.3 with ammonia water, and the reaction was carried out at 75°C for 25 minutes. After plating, the solution was annealed at 340°C for 1 hour in nitrogen. The complexing agent was sodium citrate.

[0098] S5: Take 10 parts of C / NiFe composite aerogel particles, add them to 80 parts of anhydrous ethanol, add 1.0 part of silane coupling agent, react at 50℃ for 2 hours, wash twice with anhydrous ethanol, and vacuum dry at 80℃ for 2 hours to complete surface modification. The silane coupling agent is APTES.

[0099] Prepare silicone conductive foam.

[0100] S10: Using 100 parts of vinyl-terminated polydimethylsiloxane as the matrix, add 0.5 parts of platinum vulcanizing agent, add 12 parts of surface-modified C / NiFe composite functional aerogel powder, and add 0.10 parts of crosslinking inhibitor 2-methyl-3-butyn-2-ol and 0.5 parts of organosilicon surfactant polydimethylsiloxane copolyol; disperse at 1200 r / min for 2 min under 0.06 MPa vacuum to obtain the first mixture, and vacuum dry at 115℃ for 1.5 h before adding the other materials.

[0101] S20: 20 parts of hydrogen-containing silicone oil PMHS are used as the hydrogen source for crosslinking and foaming, 80 parts of vinyl-terminated polydimethylsiloxane are used for viscosity matching, 2.0 parts of hydroxyl-terminated polysiloxane and 0.12 parts of deionized water are added as a chemical foaming promotion system, and the mixture is stirred evenly to obtain the second mixture.

[0102] S30: Mix the first mixture and the second mixture at a mass ratio of 1:(1.1), mix at 30°C for 3 min, and degas under a vacuum of 0.06 MPa for 2 min to obtain the foaming reaction material.

[0103] S40: The foaming reactant is injected into the mold and pre-cured at 90°C for 15 minutes to form stable cells, and then cured at 140°C for 40 minutes to complete the cross-linking molding and obtain a silicone conductive foam preform.

[0104] S50: The foam preform is heat-treated at 165°C for 1.5 hours to stabilize its dimensions and electrical properties; a conductive cloth is provided on one side of the foam, the conductive cloth being nickel-plated copper conductive cloth (thickness 0.04 mm), and hot-pressed at 130°C and 5.5 MPa for 12 minutes to bond it; an adhesive layer of acrylic pressure-sensitive adhesive (coating thickness 0.055 mm) is provided on the other side and covered with a 0.025 mm polyethylene release film.

[0105] Comparative Example 1

[0106] Preparation method of C / NiFe composite functional aerogel powder:

[0107] S1: Take 3 parts by weight of resorcinol and 6 parts by weight of formaldehyde and add them to 60 parts by weight of deionized water. Add 0.06 parts by weight of sodium carbonate to make the system weakly alkaline. Gel at 30°C and age for 12 hours. Then replace with anhydrous ethanol 4 times and dry at 50°C for 12 hours to obtain RF dry gel.

[0108] S2: Under nitrogen atmosphere, at 3℃·min -1 The RF dry gel was heated to 900℃ and held for 2 hours to complete the carbonization. The resulting carbon aerogel was pulverized and classified to make the particle size D50=80μm and D90≤180μm.

[0109] S3: Ten parts of carbon aerogel particles were dispersed in an ethylene glycol / water mixed solvent, and 1.17 parts of FeCl3·6H2O and 0.6 parts of FeSO4·7H2O were added. The pH was adjusted to 10 with ammonia water, and the mixture was reacted at 80℃ for 60 min and matured. After washing and drying at 70℃ for 2 h, C@Fe3O4 was obtained.

[0110] S5: Take 10 parts of C@Fe3O4, add it to 80 parts of anhydrous ethanol, add 1.0 part of silane coupling agent, react at 50℃ for 2 hours, wash twice with anhydrous ethanol, and vacuum dry at 80℃ for 2 hours to complete the surface modification. The silane coupling agent is APTES.

[0111] Prepare silicone conductive foam.

[0112] S10: Using 100 parts of vinyl-terminated polydimethylsiloxane as the matrix, add 0.5 parts of platinum vulcanizing agent, add 12 parts of surface-modified C / Fe composite functional aerogel powder, and add 0.10 parts of crosslinking inhibitor 2-methyl-3-butyn-2-ol and 0.5 parts of organosilicon surfactant polydimethylsiloxane copolyol; disperse at 1200 r / min for 2 min under 0.06 MPa vacuum to obtain the first mixture, and vacuum dry at 115℃ for 1.5 h before adding the materials.

[0113] S20: 20 parts of hydrogen-containing silicone oil PMHS are used as the hydrogen source for crosslinking and foaming, 80 parts of vinyl-terminated polydimethylsiloxane are used for viscosity matching, 2.0 parts of hydroxyl-terminated polysiloxane and 0.12 parts of deionized water are added as a chemical foaming promotion system, and the mixture is stirred evenly to obtain the second mixture.

[0114] S30: Mix the first mixture and the second mixture at a mass ratio of 1:(1.1), mix at 30°C for 3 min, and degas under a vacuum of 0.06 MPa for 2 min to obtain the foaming reaction material.

[0115] S40: The foaming reactant is injected into the mold and pre-cured at 90°C for 15 minutes to form stable cells, and then cured at 140°C for 40 minutes to complete the cross-linking molding and obtain a silicone conductive foam preform.

[0116] S50: The foam preform is heat-treated at 165°C for 1.5 hours to stabilize its dimensions and electrical properties; a conductive cloth is provided on one side of the foam, the conductive cloth being nickel-plated copper conductive cloth (thickness 0.04 mm), and hot-pressed at 130°C and 5.5 MPa for 12 minutes to bond it; an adhesive layer of acrylic pressure-sensitive adhesive (coating thickness 0.055 mm) is provided on the other side and covered with a 0.025 mm polyethylene release film.

[0117] Compared with Comparative Example 1 and Example 3, the nickel plating process in S4 was omitted, while other process flows and parameters were the same.

[0118] Comparative Example 2

[0119] Preparation method of C / NiFe composite functional aerogel powder:

[0120] S1: Take 3 parts by weight of resorcinol and 6 parts by weight of formaldehyde and add them to 60 parts by weight of deionized water. Add 0.06 parts by weight of sodium carbonate to make the system weakly alkaline. Gel at 30°C and age for 12 hours. Then replace with anhydrous ethanol 4 times and dry at 50°C for 12 hours to obtain RF dry gel.

[0121] S2: Under nitrogen atmosphere, at 3℃·min -1 The RF dry gel was heated to 900℃ and held for 2 hours to complete the carbonization. The resulting carbon aerogel was pulverized and classified to make the particle size D50=80μm and D90≤180μm.

[0122] S4: Take 10 parts of carbon aerogel particles and place them in a system consisting of 80 parts of sensitizing solution, wherein the sensitizing solution is a 0.5wt% hydrochloric acid aqueous solution containing 0.10 parts of stannous chloride, and immerse for 10 minutes.

[0123] The sensitized particles were transferred into a system consisting of 80 parts of an activation solution containing 0.003 parts of palladium chloride. The activation solution was adjusted to pH 1.5 with hydrochloric acid, and the particles were soaked for 10 minutes before being removed and rinsed with deionized water until pH 6.5 was reached.

[0124] Ten parts of activated particles were added to 150 parts of a chemical plating solution for electroless nickel plating. The chemical plating solution consisted of 3.0 parts nickel sulfate as the main salt, 0.8 parts sodium hypophosphite as the reducing agent, 1.0 part a complexing agent, and a buffer system. During plating, the pH was adjusted to 9.3 with ammonia water, and the reaction was carried out at 75°C for 25 minutes. After plating, the solution was annealed at 340°C for 1 hour in nitrogen. The complexing agent was sodium citrate.

[0125] S5: Take 10 parts of C / Ni composite aerogel particles, add them to 80 parts of anhydrous ethanol, add 1.0 part of silane coupling agent, react at 50℃ for 2 hours, wash twice with anhydrous ethanol, and vacuum dry at 80℃ for 2 hours to complete surface modification. The silane coupling agent is APTES.

[0126] Prepare silicone conductive foam.

[0127] S10: Using 100 parts of vinyl-terminated polydimethylsiloxane as the matrix, add 0.5 parts of platinum vulcanizing agent, add 12 parts of surface-modified C / Ni composite functional aerogel powder, and add 0.10 parts of crosslinking inhibitor 2-methyl-3-butyn-2-ol and 0.5 parts of organosilicon surfactant polydimethylsiloxane copolyol; disperse at 1200 r / min for 2 min under 0.06 MPa vacuum to obtain the first mixture, and vacuum dry at 115℃ for 1.5 h before adding the other materials.

[0128] S20: 20 parts of hydrogen-containing silicone oil PMHS are used as the hydrogen source for crosslinking and foaming, 80 parts of vinyl-terminated polydimethylsiloxane are used for viscosity matching, 2.0 parts of hydroxyl-terminated polysiloxane and 0.12 parts of deionized water are added as a chemical foaming promotion system, and the mixture is stirred evenly to obtain the second mixture.

[0129] S30: Mix the first mixture and the second mixture at a mass ratio of 1:(1.1), mix at 30°C for 3 min, and degas under a vacuum of 0.06 MPa for 2 min to obtain the foaming reaction material.

[0130] S40: The foaming reactant is injected into the mold and pre-cured at 90°C for 15 minutes to form stable cells, and then cured at 140°C for 40 minutes to complete the cross-linking molding and obtain a silicone conductive foam preform.

[0131] S50: The foam preform is heat-treated at 165°C for 1.5 hours to stabilize its dimensions and electrical properties; a conductive cloth is provided on one side of the foam, the conductive cloth being nickel-plated copper conductive cloth (thickness 0.04 mm), and hot-pressed at 130°C and 5.5 MPa for 12 minutes to bond it; an adhesive layer of acrylic pressure-sensitive adhesive (coating thickness 0.055 mm) is provided on the other side and covered with a 0.025 mm polyethylene release film.

[0132] Compared with Comparative Example 2 and Example 3, the in-situ generation of Fe3O in S3 was omitted. 4， The other processes and parameters are the same.

[0133] Comparative Example 3

[0134] Silica aerogel was used instead of carbon. Everything else was the same as in Example 3.

[0135] S1–S2: No RF carbon framework is prepared / carbonized; instead, silica aerogel is used as an inert porous support.

[0136] S3: 10 parts of silica aerogel particles were dispersed in an ethylene glycol / water mixed solvent, and 1.17 parts of FeCl3·6H2O and 0.6 parts of FeSO4·7H2O were added. The pH was adjusted to 10 with ammonia water, and the mixture was reacted at 80℃ for 60 min and matured. After washing and drying at 70℃ for 2 h, SiO2@Fe3O4 was obtained.

[0137] S4: Take 10 parts of SiO2@Fe3O4 composite particles and place them in a system consisting of 80 parts of sensitizing solution, wherein the sensitizing solution is a 0.5wt% hydrochloric acid aqueous solution containing 0.10 parts of stannous chloride, and immerse for 10 min;

[0138] The sensitized particles were transferred into a system consisting of 80 parts of an activation solution containing 0.003 parts of palladium chloride. The activation solution was adjusted to pH 1.5 with hydrochloric acid, and the particles were soaked for 10 minutes before being removed and rinsed with deionized water until pH 6.5 was reached.

[0139] Ten parts of activated particles were added to 150 parts of a chemical plating solution for electroless nickel plating. The chemical plating solution consisted of 3.0 parts nickel sulfate as the main salt, 0.8 parts sodium hypophosphite as the reducing agent, 1.0 part a complexing agent, and a buffer system. During plating, the pH was adjusted to 9.3 with ammonia water, and the reaction was carried out at 75°C for 25 minutes. After plating, the solution was annealed at 340°C for 1 hour in nitrogen. The complexing agent was sodium citrate.

[0140] S5: Take 10 parts of SiO2 / NiFe composite aerogel particles, add them to 80 parts of anhydrous ethanol, add 1.0 part of silane coupling agent, react at 50℃ for 2 hours, wash twice with anhydrous ethanol, and vacuum dry at 80℃ for 2 hours to complete surface modification. The silane coupling agent is APTES.

[0141] Prepare silicone conductive foam.

[0142] S10: Using 100 parts of vinyl-terminated polydimethylsiloxane as the matrix, add 0.5 parts of platinum vulcanizing agent, add 12 parts of surface-modified SiO2 / NiFe composite functional aerogel powder, and add 0.10 parts of crosslinking inhibitor 2-methyl-3-butyn-2-ol and 0.5 parts of organosilicon surfactant polydimethylsiloxane copolyol; disperse at 1200 r / min for 2 min under 0.06 MPa vacuum to obtain the first mixture, and vacuum dry at 115℃ for 1.5 h before adding the other materials.

[0143] S20: 20 parts of hydrogen-containing silicone oil PMHS are used as the hydrogen source for crosslinking and foaming, 80 parts of vinyl-terminated polydimethylsiloxane are used for viscosity matching, 2.0 parts of hydroxyl-terminated polysiloxane and 0.12 parts of deionized water are added as a chemical foaming promotion system, and the mixture is stirred evenly to obtain the second mixture.

[0144] S30: Mix the first mixture and the second mixture at a mass ratio of 1:(1.1), mix at 30°C for 3 min, and degas under a vacuum of 0.06 MPa for 2 min to obtain the foaming reaction material.

[0145] S40: The foaming reactant is injected into the mold and pre-cured at 90°C for 15 minutes to form stable cells, and then cured at 140°C for 40 minutes to complete the cross-linking molding and obtain a silicone conductive foam preform.

[0146] S50: The foam preform is heat-treated at 165°C for 1.5 hours to stabilize its dimensions and electrical properties; a conductive cloth is provided on one side of the foam, the conductive cloth being nickel-plated copper conductive cloth (thickness 0.04 mm), and hot-pressed at 130°C and 5.5 MPa for 12 minutes to bond it; an adhesive layer of acrylic pressure-sensitive adhesive (coating thickness 0.055 mm) is provided on the other side and covered with a 0.025 mm polyethylene release film.

[0147] Compared with Example 3, Comparative Example 3 uses silica aerogel instead of carbon aerogel, while other process flows and parameters are the same.

[0148] The foam preforms obtained in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests. The test methods are as follows:

[0149] Sample preparation and humidity conditioning.

[0150] Thickness: 0.60mm (±0.03mm); cut into standard test pieces.

[0151] Humidity conditioning: Test after 24 hours of placement at 23℃ / 50%RH.

[0152] (1) Volume resistivity ρ (Ω·cm)

[0153] Method: Four-probe method (the foam was pre-compressed by 10% deformation to obtain stable contact before testing).

[0154] Three points were measured on each piece and the average value was taken to reduce random errors caused by non-uniformity of the bubble cells.

[0155] (2) Electromagnetic shielding effectiveness SE (dB)

[0156] Method: ASTM D4935 coaxial clamp method, frequency band 1–10 GHz; first establish the baseline of the empty clamp, then load the sample.

[0157] Indicator: Calculate the full-band SE(f) = 20·log10(|E0 / E t |), the arithmetic mean of the frequency domain from 1 to 10 GHz is denoted as SE_avg (dB). Where E0 is the electric field strength of the empty fixture, E t It measures the electric field strength of the sample.

[0158] (3) Compression permanent deformation CS (%)

[0159] Method: Refer to ASTM D3574 (foam), compress 25%, and maintain pressure at 70℃ for 22 hours; after unloading, let stand at 23℃ for 30 minutes to measure the thickness recovery.

[0160] CS = (t0-t1) / t0 × 100% (t0 is the initial thickness, t1 is the thickness after recovery).

[0161] The smaller the CS, the better the springback / creep resistance, and the higher the long-term reliability of the assembly.

[0162] (4) Heat aging retention (heat resistance stability)

[0163] Conditions: Air oven 150℃ × 168h.

[0164] Further measurements were taken of ρ and SE, yielding the following results.

[0165] SE retention rate = SE_after / SE_before × 100%, where SE_after is the electromagnetic shielding effectiveness after thermal aging, and SE_before is the electromagnetic shielding effectiveness before thermal aging.

[0166] Δρ / ρ0 = (ρ_after - ρ_before) / ρ_before × 100%, where ρ_after is the resistivity after thermal aging, and ρ_before is the resistivity before thermal aging, i.e., ρ0. Δρ represents the change in volume resistivity of the sample under thermal aging conditions. The calculation formula is: Δρ = ρ_after - ρ_before.

[0167] The test data is shown in Table 1 below.

[0168] Table 1

[0169]

[0170] As can be seen from Table 1.

[0171] Examples 2 and 3 simultaneously achieve: low resistance (10 -2 Ω·cm level) + high SE_avg (≥55dB) + low CS (≤9.5%) + high heat aging retention (≥93%).

[0172] This demonstrates that the conductive network is not only interconnected, but also geometrically and interfaceally stable under thermal / mechanical conditions; shielding is not solely based on reflection, but rather a combination of reflection, absorption, and scattering.

[0173] Ni (metallic phase): provides through-conductivity and skin effect reflection; the Ni / Ni3P+ thin passivation layer formed after chemical plating and annealing reduces oxygen / water penetration and suppresses resistance drift.

[0174] Fe3O4 (magnetic phase): provides magnetic loss (μ″) and particle-level multiple scattering, changing the electromagnetic wave "escape after one reflection" into a long-path dissipation of "reflection-absorption-rescattering-reabsorption"; at the same time, it acts as a heat diffusion micronode, weakening network instability caused by hot spots.

[0175] Carbon aerogel framework (structural phase): Three-dimensional interconnected channels enable Ni / Fe3O4 to be anchored in situ, significantly reducing the percolation threshold, and improving network stability and resilience (reduced CS) through dielectric loss (ε″) and in-plane thermal conductivity.

[0176] As can be seen from Comparative Example 1 (without nickel plating), the conductivity / shielding / heat resistance properties decrease. ρ decreases from 10 -2 Increased to 0.25Ω·cm; SE_avg36dB; thermal aging Δρ / ρ0+48%, SE retention 77%.

[0177] This is because the absence of Ni leads to a lack of metal bridging (broken through channels) and skin effect reflection (weak high-frequency reflection), resulting in an upward shift in the percolation threshold and a downward shift in SE. At the same time, the absence of a Ni / Ni3P passivation film makes it easier for oxygen / water to penetrate, deteriorating the interfacial resistance and interparticle contact, leading to amplified resistance drift and continuous SE decay after thermal aging.

[0178] As can be seen from Comparative Example 2, the lack of Fe3O4 has a relatively small impact on conductivity; however, the SE retention rate is significantly reduced. ρ is similar to that of Example 3, but SE_avg is only 41 dB, and 83% of the SE is retained after thermal aging.

[0179] This is because SE = reflection (σ) + absorption (ε″ / μ″) + multiple scattering. Ni only provides reflection channels; without the μ″ and micro-scattering of Fe3O4, there is a lack of long-chain dissipation for "reabsorption," which is particularly noticeable at high frequencies. Simultaneously, the lack of Fe3O4's thermal diffusion nodes makes the network more prone to hotspots / contact deterioration under thermal stress, leading to a decrease in retention rate. This is because Fe3O4 and Ni are functionally complementary, jointly supporting "high-frequency shielding and thermal stability," and cannot replace each other.

[0180] Comparative Example 3 exhibits a comprehensive degradation with increased ρ, decreased SE, and increased CS, with ρ rising to 0.60 Ω·cm, SE avg 19 dB, and CS 12.0%. The carbon framework provides a three-dimensional connectivity carrier and short-range skip bridges, significantly reducing the percolation threshold and assisting in energy dissipation, hotspot suppression, and stress concentration through dielectric loss and in-plane thermal conductivity. SiO2 is an inert insulator, and Ni / Fe3O4 only forms discrete point contacts, making network connectivity difficult. Poor interfacial compatibility makes it difficult for the pores to fully rebound after compression, leading to an increase in CS. It can be seen that the carbon framework is a structure-function integrated base, and cannot be equivalently replaced by "replacing the pores with other porous materials."

[0181] In summary, this invention achieves synergistic enhancement in multiple dimensions of conductivity, shielding, mechanical durability, and heat resistance through the in-situ construction of carbon skeleton (three-dimensional connectivity / dielectric loss / springback), Fe3O4 (magnetic loss / multi-scattering / thermal diffusion), and Ni (through-conductivity / skin effect / antioxidation) and the synergistic process of chemical plating-annealing.

[0182] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing high-performance conductive foam, characterized in that, Comprising the following steps: S10: 100 parts of end-vinyl polydimethylsiloxane as a base, 0.2-2.0 parts of platinum sulfuration agent, 8-22 parts of C / NiFe composite functional aerogel powder, and 0.05-0.15 parts of cross-linking inhibitor 2-methyl-3-butyn-2-ol and 0.2-1.0 parts of silicone surfactant polydimethylsiloxane copolyol are added; the first mixture is obtained by dispersing at 800-1500 r / min under 0.05-0.08 MPa vacuum for 1-3 min, and vacuum drying at 110-120°C for 1-2 h before feeding; S20: 15-30 parts of hydrogen-containing silicone oil is used as a cross-linking and foaming hydrogen source, 70-100 parts of end-vinyl polydimethylsiloxane is used for viscosity matching, 1.0-5.0 parts of hydroxyl-terminated polysiloxane and 0.05-0.30 parts of deionized water are added as a chemical foaming promotion system, and the second mixture is obtained by stirring uniformly; S30: The first mixture and the second mixture are mixed at a mass ratio of 1:(1.0-1.2), mixed at 25-35°C for 2-5 min, and defoamed under 0.05-0.08 MPa vacuum for 1-3 min to obtain a foaming reaction material; S40: The foaming reaction material is injected into a mold, pre-cured at 80-100°C for 10-20 min to form stable cells, and then post-cured at 120-150°C for 30-60 min to complete cross-linking and molding, to obtain a silicone conductive foam body; S50: The foam body is heat treated at 150-180°C for 1-2 h; a conductive cloth is arranged on one side of the foam, the conductive cloth is a nickel-plated copper conductive cloth, and the other side is provided with an adhesive layer of acrylic pressure-sensitive adhesive and covered with a 0.02-0.03 mm polyethylene release film; The preparation method of the C / NiFe composite functional aerogel powder is as follows: S1: 2-4 parts of resorcinol and 3-6 parts of formaldehyde are added to 40-80 parts of deionized water, 0.02-0.10 parts of sodium carbonate is added to make the system weakly alkaline, and the system is gelled and aged at 25-35°C for 6-24 h; then anhydrous ethanol or acetone is used for replacement for 3-5 times, and the system is dried at 40-60°C for 8-16 h to obtain an RF dry gel; S2: heating at 2-5℃ min under nitrogen atmosphere -1 The RF dry gel is heated to 800-1000℃ and kept for 1-3h to complete carbonization, and the obtained carbon aerogel is crushed and classified to make the particle size D50=50-120μm, D90≤180μm; S3: 10 parts of carbon aerogel particles are dispersed in an ethylene glycol / water mixed solvent, 1.0-2.5 parts of ferric chloride and 0.3-1.2 parts of ferrous sulfate are added, the pH is adjusted to 9-11 with ammonia water, and the system is reacted at 60-90°C for 30-90 min and aged, then washed and dried at 60-80°C for 1-3 h to obtain C@Fe3O4; S4: 10 parts of C@Fe3O4 composite particles are placed in a system composed of 50-100 parts of a sensitization liquid, the sensitization liquid is 0.1-1.0 wt% hydrochloric acid aqueous solution containing 0.05-0.20 parts of stannous chloride, and the system is immersed for 5-15 min; The sensitized particles are transferred into a system consisting of 50-100 parts of activation solution containing 0.001-0.010 parts of palladium chloride, and the activation solution is adjusted to pH=1-2 with hydrochloric acid, immersed for 5-15 min, taken out and rinsed with deionized water to pH=6-7; 10 parts of the activated particles are added into 100-200 parts of electroless plating solution for electroless nickel plating, the electroless plating solution is composed of 1.0-5.0 parts of nickel sulfate as main salt, 0.3-1.5 parts of sodium hypophosphite as reducing agent, 0.5-2.0 parts of complexing agent and buffer system, and ammonia is used to adjust pH=8.5-10.0 during plating, the reaction is carried out at 60-85℃ for 10-40 min, and the plated particles are annealed in nitrogen at 300-400℃ for 0.5-2h; the complexing agent is sodium citrate and / or lactic acid; S5: 10 parts of C / NiFe composite aerogel particles are added into 50-100 parts of anhydrous ethanol or toluene, 0.5-2.0 parts of silane coupling agent is added, and the reaction is carried out at 40-60℃ for 1-3h, the surface modification is completed by washing with anhydrous ethanol for 2-3 times and vacuum drying at 80℃ for 1-3h; the silane coupling agent is APTES and / or VTMS.

2. The method for preparing high-performance conductive foam according to claim 1, characterized in that, The thickness of the electric cloth is 0.03-0.05mm.

3. The method for preparing high-performance conductive foam according to claim 1, characterized in that, The coating thickness of the acrylic pressure-sensitive adhesive is 0.05-0.06mm.

4. A high performance conductive foam, characterized by, The preparation method is prepared according to any one of claims 1-3. The preparation method is prepared according to any one of claims 1-3.

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