【作者】 杨益；

【导师】 肖鹏；

【作者基本信息】 中南大学 ， 粉体材料科学与工程， 2012， 硕士

【摘要】 碳纤维具有低密度、高强度、高导热性和优异的高温力学性能,在高温隐身领域有良好的应用前景。本文通过电镀镍、硅溶胶/wcnt改性、碳纤维排布三组实验,分别研究了镀镍工艺对镀镍层形貌、电磁性能的影响,浸渍溶液成分对Si02涂层形貌及电磁性能的影响,不同碳纤维排布方式对反射率的影响。得到如下结论：电镀时间和电流不同,镍颗粒的形貌和生长机理不同。随时间延长,镍颗粒形貌由初始颗粒变为针状颗粒。电流为O.1A时镍颗粒的生长呈Frank-van der Merwe(F-M)模式,电流为0.2A时镍颗粒的生长Volmler-Weber(V-W)模式。镍颗粒对纤维的电磁性能有重要影响：镍颗粒为孤立的颗粒时,可以提高碳纤维的吸波性能；镍颗粒相互接触时,会降低碳纤维的吸波性能。硅溶胶浓度较高时,涂层连续性较好,随硅溶胶浓度的降低,涂层连续性降低。碳纳米管具有较高的表面能,会促使Si02团聚,提高碳纤维介电常数的实部；短碳纤维及无纬布是低损耗物质,对电磁波有强烈的反射作用。干涉消波对改善材料的吸波性能起重要作用,通过炭纤维预制体的结构控制,可使电磁波产生干涉消波,降低反射率,反射率可达—17.07dB,反射率低于—10dB的带宽为4.3GHz。在实验含量范围内,短切碳纤维含量提高,反射率降低。随频率增加,炭纤维的趋肤效应显著增强,涡流损耗增大,反射率降低。更多还原

【Abstract】 Carbon fiber has excellent properties, such as low density, high strength,high thermal conductivity and excellent high temperature mechanical performance. There are good prospects for application in the field of high temperature stealth. Three sets of experiment including electroless nickel, silica sol/wcnt modified carbon fiber, arranged carbon fiber were designed. The factors affecting the morphology of electroless nickel and silica sol/wcnt modified carbon fiber were investigated respectively. Electromagnetic properties of electroless nickel, silica sol/wcnt modified carbon fiber, arranged carbon fiber were briefly discussed.Under different electroplating conditions,there will be two different morphologies of nickel particles:one is the initial nickel particles; a needle-like particles catalytic growed on the initial particles. With the current changes, the mode of nickel layer growth changes, When the current is0.1A,the nickel particles growas Frank-van der Merwe (FM) mode, the current of0.2A,nickel particles grow as Volmler-Weber (VW) mode. Nickel particles as isolated particles, can improve the absorbing properties of carbon fiber,or it will reduce the absorbing properties of carbon fiberThe silica sol concentration reducing, continuity of the coating is depraved. carbon nanotubes joined lead to SiO2reunion, and improve the real part of dielectric constant of the carbon fiber.The UD plate and short carbon fiber have a strong reflection of electromagnetic waves but electromagnetic interference can reduce the reflectivity. The short carbon fiber content is beneficial for reducing the refiectivity.The electromagnetic interference plays an important roie in improving the absorbing properties of the materials, for sample with vertical-arrangement UD plate,absorption of-16dB,and the-5dB effective bandwidth of7GHz.更多还原