8results about How to "Enhanced interfacial polarization" patented technology

The invention discloses a self-repairing wave-absorbing composite material as well as a preparation method and application thereof. The self-repairing wave-absorbing composite material provided by the invention comprises the following components in percentage by mass: 30-80% of a polyurethane matrix; 20%-70% of composite wave absorbing powder; the composite wave-absorbing powder is prepared by performing plasma ball milling on graphene oxide and soft magnetic metal powder. The preparation method of the self-repairing wave-absorbing composite material comprises the following steps: 1) preparing a polyurethane prepolymer solution; and 2) dispersing the composite wave-absorbing powder in a polyurethane prepolymer solution, injecting the solution into a mold, and carrying out curing molding to obtain the self-repairing wave-absorbing composite material. The self-repairing wave-absorbing composite material disclosed by the invention is excellent in wave-absorbing property and mechanical property, the material can realize quick self-repairing, the stability of the wave-absorbing property and the mechanical property is ensured, and the composite material is suitable for the fields of 5G communication, new energy automobiles, national defense and military industry and the like.

The invention provides a preparation method of a carbon / magnetic metal / aramid nanofiber composite aerogel wave-absorbing material, and belongs to the field of wave-absorbing material preparation, and the preparation method comprises the following steps: (1) respectively preparing a polyvinyl alcohol solution, an aramid nanofiber solution, a polyphenol solution and a magnetic metal salt solution; (2) sequentially adding the aramid nanofiber solution, the polyphenol solution and the magnetic metal salt solution into the polyvinyl alcohol solution, and stirring at room temperature to uniformly disperse the mixed solution; and (3) pouring the uniformly dispersed solution into a mold for freezing and freeze-drying. And (4) finally, carbonizing the dried sample in an inert atmosphere to obtain the carbon / magnetic metal / aramid nanofiber composite aerogel. The method is easy to operate and environmentally friendly, and the prepared carbon / magnetic metal / aramid nanofiber composite aerogel has excellent wave absorbing performance and mechanical performance.

The invention relates to a preparation method of a lightweight reduced graphene oxide-silicon dioxide electromagnetic wave absorbing material. The invention belongs to the technical field of electromagnetic wave absorbing materials. The invention solves the problems that the impedance of the existing reduced graphene oxide is mismatched, the density of the modified reduced graphene oxide composite wave-absorbing material is increased and the preparation method is complicated. The method comprises the following steps: performing chemical crosslinking on graphene oxide, silicon dioxide and a silane coupling agent to obtain a precursor; and drying and sintering the precursor. The material prepared in the invention has good impedance matching and abundant interface polarization and relaxation effects, can effectively reduce the reflection loss value of electromagnetic waves and increase the effective absorption bandwidth of the electromagnetic waves, and has excellent electromagnetic wave absorption performance. When the thickness of the material is only 1.5 mm, the RL of the material can reach-54.08 dB, and when the thickness of the material is 1.7 mm, the effective absorption bandwidth of the material can reach 5.12 GHz. In addition, the density of the material is only 0.083 g / cm < 3 >, the process is simple, and stable batch production can be realized.

The present invention provides a method for preparing a carbon / magnetic metal / aramid nanofiber composite aerogel absorbing material, which belongs to the field of absorbing material preparation. The preparation method comprises the following steps: (1) respectively preparing a polyvinyl alcohol solution, an aramid nanofiber solution, a polyphenol solution and a magnetic metal salt solution. (2) sequentially adding the aramid nanofiber solution, the polyphenol solution and the magnetic metal salt solution to the polyvinyl alcohol solution, and stirring at room temperature to make the mixed solution uniformly dispersed. (3) pouring the uniformly dispersed solution into a mold, freezing and freeze-drying. (4) Finally, carbonizing the dried sample under an inert atmosphere to obtain a carbon / magnetic metal / aramid nanofiber composite aerogel. The present invention is simple to operate and environmentally friendly. The prepared carbon / magnetic metal / aramid nanofiber composite aerogel has excellent absorbing performance and mechanical properties.

This invention belongs to the field of electromagnetic wave absorbing materials technology, specifically relating to an absorbing material, its preparation method, and its application. This invention uses multi-walled carbon nanotubes (MWCNTs), potassium permanganate (KMnO4), and divalent manganese as raw materials, based on Mn... 2+ With MnO4 ‑ The redox reaction between the two components allows for in-situ uniform loading of MnO2 nanoparticles onto the MWCNT surface through simple stirring in a room-temperature liquid environment, resulting in microwave absorption performance superior to most similar absorbing materials. Compared to traditional methods for preparing absorbing materials, the technical route of this invention offers significant advantages, including simple preparation process, no pollutant emissions, energy-saving and environmentally friendly process, adjustable and controllable material structure, excellent microwave absorption performance, and scalability. This method effectively overcomes the technical limitations in the preparation of absorbing materials, providing a scalable new paradigm for the green and large-scale production of high-performance absorbing materials.

The application discloses a preparation method of a high-strength flexible self-supporting hydrophobic electromagnetic shielding film, which comprises the following steps: weighing a certain amount of carbon titanium-aluminum, slowly adding the carbon titanium-aluminum into a lithium fluoride / hydrochloric acid etching solution, magnetically stirring in a water bath at a certain temperature for a period of time, obtaining an etched carbon titanium-aluminum dispersion liquid, carrying out acid pickling on the carbon titanium-aluminum dispersion liquid by using dilute hydrochloric acid, and then washing the carbon titanium-aluminum dispersion liquid until neutral, so as to obtain multi-layer titanium carbide; carrying out ultrasonic treatment on the multi-layer titanium carbide, so as to obtain few-layer titanium carbide; mixing the prepared few-layer titanium carbide and bacterial cellulose with nano-iron oxide respectively; alternately performing vacuum filtration on the mixed solutions of bacterial cellulose / nano-iron oxide and few-layer titanium carbide / nano-iron oxide; and naturally airing the obtained film at room temperature. Finally, methyltrimethoxysilane is deposited on the surface of the film to form a hydrophobic network. The film prepared by the method has the characteristics of good flexibility, high electromagnetic shielding performance and high mechanical strength.

This invention relates to the field of functional material preparation technology, and discloses an epoxy resin-based composite microwave absorbing material and its preparation method. The method includes preparing a polyaniline / ferric oxide / titanium dioxide ternary composite microwave absorbing agent, surface-coating it with boron nitride nanosheets to obtain a modified composite microwave absorbing agent; preparing a thermally conductive matrix layer slurry and a microwave absorbing functional layer slurry respectively; applying the microwave absorbing functional layer slurry to the bottom of a mold using a doctor blade coating method, pre-curing it, then pouring the thermally conductive matrix layer slurry onto it, and finally curing it to obtain a two-layer composite material. This invention enhances dielectric loss through the microcapacitance effect within the microwave absorbing functional layer, while simultaneously utilizing the thermally conductive matrix layer to construct a continuous thermally conductive network, thus alleviating the problem of mutual constraint between microwave absorption and thermal conductivity performance.

The invention belongs to the technical field of wave-absorbing materials, and particularly discloses a low-dimensional mixed carbon network based on iron-based MOF and a preparation method thereof.The preparation method comprises the following steps that S1, ferrite, zinc salt, 2-methylimidazole and polyvinylpyrrolidone are dissolved in water to form a mixed solution for compounding, and then centrifugal drying is conducted to obtain Fe-ZIF-L of a two-dimensional hexagonal sheet structure; and S2, pyrolyzing the precursor iron-based MOF at the pyrolysis temperature of 600-750 DEG C, so that the precursor iron-based MOF is converted into a low-dimensional mixed carbon network in which two-dimensional carbon sheets and carbon nanotubes are connected with each other. The low-dimensional mixed carbon network prepared by utilizing a one-step pyrolysis method is simple and easy to operate and has excellent wave absorbing performance, and relatively high reflection loss and relatively wide effective bandwidth are realized under relatively low matching thickness.