石墨烯复合吸波剂的制备及电磁防护性能研究

发布时间：2018-04-23 17:11

本文选题：石墨烯 + 丁腈橡胶　；参考：《北京理工大学》2015年硕士论文

【摘要】：电磁污染广泛存在于环境中，电磁波吸收是防治电磁污染的有效途径之一。随着科技的进步，对吸波材料的需求越来越大，研发具有厚度薄、质量轻、频带宽、吸收强吸波材料是未来的发展方向。石墨烯具有优良的导电性、热稳定性好、电子迁移率高、低密度的优点，是一种极有发展前景的吸波材料。本文首先用化学还原氧化石墨法制备了还原氧化石墨烯，对比了不同厚度的高品质石墨烯与还原氧化石墨烯的吸波性能。高品质石墨烯吸波性能较弱，且随厚度和缺陷增加吸波性能有微小的增加，KNG-180反射损耗最低只有-0.85dB。还原氧化石墨烯由于低介电常数阻抗匹配性能好，存在的缺陷有利于电子通过从连续态到费米能级的跃迁，并且有三元弛豫过程，具有较强的电磁波吸收能力。还原氧化石墨烯比高品质石墨烯的吸波性能好得多。在7.4GHz处反射损耗峰值达-6.88dB。均匀混合还原氧化石墨烯与丁腈橡胶于二甲苯溶剂中，在常温下固化成弹性体，制成石墨烯/丁腈橡胶复合吸波材料。石墨烯片在丁腈橡胶中能均匀分散，形成大的导电网络和反角，有利于提高吸波性能。还原氧化石墨烯/丁腈橡胶复合材料在还原氧化石墨烯质量分数为10%下的计算反射损耗在2mm厚度下，16.2GHz处反射损耗最小值达到-38.70dB，反射损耗＜-10dB的频率范围在14.6GHz～18GHz。复合材料结合了还原氧化石墨烯轻质和高电磁波吸收性能与丁腈橡胶高柔韧性、可加工性以及耐高温性能优点，可以制成结构型吸波材料，具有很好的发展前景。羰基铁粉在2～18GHz频率范围具有一定的吸波性能，但只有在16～18GHz很窄的带宽下反射损耗在-10dB以下。通过简易湿法化学法制备还原氧化石墨烯/羰基铁粉复合材料，该复合材料吸波性能优越，氧化石墨和羰基铁粉质量比为3:20，在3mm厚度下可以产生以9.4GHz为中心的强而宽的吸波峰，峰值可达-52.18dB。在7.8～11.6GHz频率范围内，反射损耗低于-10dB，在8.8～10.0GHz频率范围内，反射损耗低于-20dB。提出碳桥理论解释吸波机理，该复合材料兼具磁损耗与介电损耗，，有利于实现阻抗匹配和吸收频带的拓宽，且能降低复合材料的密度。
[Abstract]:Electromagnetic pollution exists widely in the environment, and electromagnetic wave absorption is one of the effective ways to prevent electromagnetic pollution. With the development of science and technology, the demand for absorbing materials is increasing, and the research and development has the characteristics of thin thickness, light weight, frequency bandwidth, absorption of strong absorbing materials is the future development direction. Graphene has the advantages of excellent electrical conductivity, good thermal stability, high electron mobility and low density. In this paper, reductive graphene was prepared by chemical reduction oxidation graphite method, and the wave absorption properties of high quality graphene with different thickness were compared with those of reduced graphene oxide. The high quality graphene has weak absorbing property, and the minimum reflection loss of KNG-180 is -0.85 dB with the increase of thickness and defect. Because of the good matching performance of the low dielectric constant impedance, the reduced graphene oxide has the advantage of the electron transition from the continuous state to the Fermi energy level, and has a ternary relaxation process, which has a strong electromagnetic wave absorption ability. Reduced graphene oxide is much better than high quality graphene in absorbing wave. The peak value of reflection loss at 7.4GHz is -6.88 dB. Graphene / acrylonitrile-butadiene rubber (NBR) / graphene / nitrile rubber (NBR) composite wave absorbing material was prepared by uniformly mixing reduced graphene and nitrile butadiene rubber in xylene solvent and curing into elastomer at room temperature. Graphene sheet can be dispersed uniformly in NBR, forming a large conductive network and reverse angle, which is helpful to improve the absorbing property of NBR. The composites combine the light weight and high electromagnetic wave absorption properties of reduced graphene with the advantages of high flexibility, processability and high temperature resistance of nitrile rubber. The composites can be made into structural absorbing materials and have a good development prospect. The carbonyl iron powder has a certain absorbing property in the 2~18GHz frequency range, but only under the narrow bandwidth of 16~18GHz, the reflection loss is less than -10 dB. The peak value can reach -52.18 dB. In the 7.8~11.6GHz frequency range, the reflection loss is lower than -10 dB, and in the 8.8~10.0GHz frequency range, the reflection loss is lower than -20 dB. The carbon bridge theory is proposed to explain the absorbing mechanism. The composite has both magnetic loss and dielectric loss, which is helpful to realize impedance matching and broaden the absorption band, and can reduce the density of the composite.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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