Research About Metallization On The Surface Of Carbon Fibers And Shielding Properties Of Composite Materials

With the increasing severity of electromagnetic radiation, most countries devote to study electromagnetic shielding materials with high efficiency and low density. Because of their excellent properties, such as light quality, good mechanical performance and so on, carbon fibers(CFs) were widely used as reinforced materials. However, relatively low electrical and magnetic properties of CFs limit their broad applications in electromagnetic shielding materials. Traditional plating process was used to fabricate iron nickel(Fe-Ni) alloy coated continuous CFs(Fe-Ni-CFs), and their microstructures, compositions, magnetic properties and formation mechanism were also studied. The Fe-Ni-CFs combined with the ABS resin were used to prepare composites and the electromagnetic shielding performances were also evaluated. The composite materials possess many outstanding advantages and are expected to have wide applications in the field of electromagnetic shielding materials.The main results proposed in this thesis were shown as follow:(1) Co-electrodeposition method was adopted to obtain the Fe-Ni-CFs successfully, and effects of the process parameters on microstructures and properties of the Fe-Ni-CFs were discussed. The results showed that oxidation treatment of CFs at 400 °C and electrodepositing at 60 °C for 15 min were the best parameters to get Fe-Ni-CFs. And the coatings were mainly composed by FeNi3 and Fe content in the coatings could reach 9 wt%. Besides, coatings showed good adhesion with the CFs. Line resistance value of Fe-Ni-CFs could maintain under 12 ?/m. However, the saturation magnetization only reached 20 emu/g and needed to be further improved.(2) In order to improve Fe content in the coatings, two-step electrodeposition method was firstly used to fabricate Fe-Ni-CFs and the effects of annealing treatment on the morphology and phase composition were also studied. The results showed that Fe content of coatings was enhanced to 18.4 wt%, and saturation magnetization value could reach 50 emu/g. After annealed, surface quality of the Fe-Ni-CFs was improved obviously and the line resistance value could maintain under 5 ?/m. Although the magnetic saturation value of Fe-Ni-CFs decreased slightly after annealed, it still could reach 25 emu/g and showed typical soft magnetic performances.(3) Hot pressing molding process was adopted to prepare the Fe-Ni-CFs/ABS composites. It was shown that the composites had better shielding effectiveness performance in 30~1200 MHz frequency range than the CFs/ABS. In addition, the Fe-Ni-CFs could effectively reduce the surface resistance and volume resistance of the composite materials, indicating that the Fe-Ni-CFs proposed in this thesis will be novel filler in electromagnetic shielding composites.