石墨烯水泥基复合材料吸波性能及机理研究

Cement based electromagnetic wave absorbing material, which is compounded by the cement matrix and absorbing agent, possesses high microwave absorption property and enhanced bearing capacity, and thus has a promising prospect in military stealth technology and civil electromagnetic wave pollution protection. Graphene sheet is a sp2-hybridization carbon nanomaterial with extraordinary mechanical, thermal and electrical properties. The graphene sheet cement based composites are expected to have good electromagnetic wave absorption performance. The present research aims to investigate electromagnetic wave absorbing properties and mechanism of graphene sheet cement based composites. To achieve the above research goal, the following tasks will be performed. (1) To improve the homogeneity of graphene sheet in suspension and cement matrix, physical/chemical dispersion technologies will be studied.(2)To reveal the impact of graphene sheet on electromagnetic wave attenuation and absorption of cement based composites, the electromagnetic parameters like dielectric constant, magnetic conductivity, resistivity and wave absorption properties like impedance matching property, reflectivity, absorbance bandwidth of cement based composites will be investigated through the transmission network simulation of electromagnetic wave in cement based composites by transmission line theory.(3) To regulate and control the electromagnetic wave impedance matching characteristics and absorbing performance of cement based composites, the impact of combined addition of other absorbing agent and the multi-layer structure design on electromagnetic parameter and wave absorption performance of cement based composites will be researched.(4)To provide theoretical basis for the design and preparation of new cement based electromagnetic wave absorbing composite, the electromagnetic wave absorption mechanism of graphene sheet cement composite will be investigated.

水泥基吸波材料是由水泥基体与吸波剂复合而成，同时具备良好的电磁波吸收能力和结构承载能力，在解决军事隐身技术、民用电磁波污染等方面具有重要发展前景。石墨烯是由碳原子经sp2杂化而成的二维碳纳米材料，具有优异的电学、热学和力学性能。石墨烯水泥基复合材料预期具备良好的吸波性能。课题通过研究石墨烯的物理、化学分散技术，解决其在水泥基材料中的分散均匀性问题；通过传输线理论模拟电磁波在水泥基材料中的传输网络，研究石墨烯水泥基复合材料介电常数、磁导率、电阻率等电磁参数以及电磁波阻抗匹配特性、反射率、吸波频宽等吸波性能，掌握石墨烯对水泥基复合吸波材料电磁波衰减及吸收作用的影响规律；通过研究复合其它吸波剂及多层结构设计对石墨烯水泥基复合材料电磁参数及吸波性能的影响规律，掌握调控电磁波阻抗匹配特性及吸波效能的方法；通过研究石墨烯水泥基复合材料吸波作用机理，为新型水泥基复合吸波材料设计及制备提供重要理论依据。

石墨烯(GNPs)具有优异的电磁学、力学性能，因此石墨烯水泥基复合材料(GNPs/CC)通常具备较好的电学、磁学、力学性能。课题研究了GNPs的水性分散及机理、GNPs/CC电磁波吸波性能及机理、GNPs/CC多层结构吸波性能优化以及GNPs/CC吸波性能数值模拟。.①GNPs的水性分散。采用表面活性剂溶液取代去离子水作为基准液，可提高紫外吸光度表征GNPs分散效果的准确性。分散剂单掺时GNPs水性分散效果最好的分散剂是2.5g/L的SDBS，分散剂复掺时GNPs水性分散效果最优的分散剂组合是2.5g/L的 SDBS与0.4g/L的 CO890，二者复掺优于单掺分散剂。.②GNPs/CC吸波性能及机理。GNPs、镍锌铁氧体(Ni0.4Zn0.6Fe2O3)、导电聚苯胺(PANI)、电解二氧化锰(EMD)改善水泥基材料吸波性能最优掺量分别为1.0%、30.0%、3.0%、10.0%。当GNPs、Ni0.4Zn0.6Fe2O3复配掺量分别为1.0%、30%时，具有最优吸波性能，其最低电磁波反射率、有效吸波频宽分别为-32.1dB、5.4GHz。GNPs可显著改善水泥基材料的介电常数，GNPs、PANI对水泥基复合材料电阻率降低效果显著，而Ni0.4Zn0.6Fe2O3可明显改善水泥基材料磁导率。.③GNPs/CC多层结构设计研究。随水泥基材料设计层数增加，基体电磁波反射率曲线逐渐平缓，当三层水泥基复合材料的阻抗匹配层、阻抗过渡层、损耗吸波层中的吸波介质分别为EMD、GNPs/EMD、GNPs/ Ni0.4Zn0.6Fe2O3时，基体试样最低电磁波反射率、有效吸波频宽分别为-12.6dB、7.7GHz。在三层水泥基复合材料的阻抗匹配层中掺入粒径为3mm，掺量为0.2%的EPS颗粒后，试样最低电磁波反射率值可低至-54dB，有效吸波频宽接近11.2GHz。外凸型异形结构表面对基体电磁波反射率的降低作用优于内凹型异形结构。.④GNPs/CC吸波性能数值模拟。GNPs、PANI主要通过影响基体对入射电磁波的电响应调控电磁波入射及损耗，Ni0.4Zn0.6Fe2O3主要通过影响基体对入射电磁波的磁响应调控电磁波的损耗。同时，三层水泥基材料细化了水泥基材料与空气介质间电磁波阻抗梯度，增加了电磁波入射量，基体内部各吸波介质与电磁波损耗衰减作用几率增大，降低了基体电磁波反射率。