Research On Surface Metallization Of Continuous Carbon Fiber And The Electromagnetic Shielding Property Of Its Composite

With rapid development of electronic devices with high frequency and digitization, the unprecedent deterioration of the electromagnetic environment in the limited space seriously impacts on social process and human survival, and harmonious environment and sustainable development of ecological environment. Therefore, the research and development of the electromagnetic shielding material have attracted extensive attention. With the development of technology, the research of electromagnetic shielding materials focus on the high shielding efficiency and low density direction. Due to high strength, light weight and good conductivity properties of carbon fiber, it can be directly used for preparation of light shielding material. In this work, metalized carbon fiber was filled in low density polymer matrix materials and used to fabricate novel high efficiency and low weight electromagnetic shielding composites, and is expected to play an important role in the electromagnetic shielding material field.In this work, the surface modification process of electroless and elecdeposition of carbon fiber was investigated. Especially, the manufactured equipment to synthesis of the long carbon fiber prepared by the continuous nickel electrodeposition was developed for the first time, which was applied for the fabrication of as-prepard carbon fiber with the dense and uniformly coatings with the adjustable thickness.The electromagnetic shielding effectiveness of three-dimensional braided nickel-plated carbon fiber/epoxy (Ni-CF_3D/EP) composite is about 40 dB higher than that of three-dimensional braided carbon fiber/epoxy (CF_3D/EP) composite in the frequency of 30¹50 MHz. By correction of calculation model of electromagnetic shielding efficiency of Shapi Luo screen materials, we get a suitable calculation model of electromagnetic shielding efficiency to woven materialsThe silicone rubber filled with nickel-plated carbon fiber (Ni-CF/VMQ) composite, when the fiber content is 80 phr, the composite achieves the best overall performance. The electromagnetic shielding effectiveness is more than 80 dB in the frequency of 30¹200 MHz. The tensile strength is 3.23 MPa, and the density is 1.37 g/cm³.According to Schelkunoff electromagnetic shielding theory, we studied the high conductivity and high permeability composite coatings of nickel/Fe₃O₄ nanoparticles (Ni/Fe₃O₄-NPs) on the surface of carbon fiber, and the deposition mechanism of composite coating. It was founded that the experimental data were fully consistent with the model of two-step adsorption theory. It demonstrates that the deposition process of Ni/Fe₃O₄-NPs composite coating is suitable for model of the two-step adsorption theory. We also prepared the composite of Ni/Fe₃O₄-NPs carbon fiber. The test results show that the electromagnetic shielding effectiveness of the composite of carbon fiber with Ni/Fe₃O₄-NPs coatings is 10 dB higher than that without Fe₃O₄-NPs.In conclusion, the filling electromagnetic shielding composite material filled with metalized carbon fiber have excellent electromagnetic shielding performance. It was confirmed in this work that the theory of material with both high conductivity and high permeability could obtain high electromagnetic shielding performance, providing the new train of thought and research foundation for the design and research of novel electromagnetic shielding materials.