【作者】 陈敏；

【导师】 孙润军； 董子靖；

【作者基本信息】 西安工程大学 ， 纺织材料与纺织品设计， 2021， 硕士

【摘要】 在信息化飞速发展的时代,电磁波作为信息传播的载体,已广泛应用于生活的方方面面,为物质文明的发展和社会进步作出了巨大贡献。与此同时,电磁波给环境带来的污染以及对人体健康造成的伤害也不容忽视。因此吸波材料的研究成为一大热点。目前吸波材料存在的共性问题是难以同时兼顾“质量轻、频带宽、厚度薄、吸波能力强”这四大要求。针对上述问题,本文选取钡铁氧体(Ba Fe₁₂O₁₉,石墨烯（graphene）、聚苯胺（PANI）为吸收剂,采用机械混合法制备多元吸收剂单层及三层涂层织物。从吸波机理出发,通过吸收剂配比的调控以及涂层结构的设计优化涂层织物的吸波性能,最终制备出厚度薄、吸波性能优异且兼具承载性能的柔性吸波材料。首先,采用微波水热法制备六角片状结构的纯相Ba Fe₁₂O₁₉,以其为吸收剂制备吸波涂层织物,涂层厚度为1.2 mm时,在13.15GHz处的最小反射损耗RL值为-17.19d B,有效吸收带宽（RL﹤-10）为1.22 GHz,平均吸收率为37.21%。可见,单一损耗机制的涂层织物吸波效果不佳,采取与graphene复合来弥补其损耗机制单一、密度大、阻抗匹配不佳的问题。采用流延法制备五种不同质量比的Ba Fe₁₂O₁₉/graphene单层涂层织物,实验结果表明,涂层厚度为1.2 mm,Ba Fe₁₂O₁₉:graphene=6:1时,吸波性能最佳,最小反射损耗RL值可达-36.83 d B,有效吸收带宽可达4.04 GHz,且平均吸收率为78.79%。吸波性能大大提高。为了进一步优化织物吸波性能,通过流延法制备六种不同吸收剂配比的Ba Fe₁₂O₁₉/graphene/PANI单层涂层织物,织物的涂层厚度为1.2 mm时,在13.76 GHz处的最小反射损耗RL值可达-37.36 d B,有效吸收带宽达到5.40 GHz。由于三相吸收剂之间的相互作用及协同效应,织物的吸波性能进一步得到提高。对涂层结构进行设计,制备Ba Fe₁₂O₁₉/graphene/PANI三层涂层织物,相对单层涂层织物而言,其吸波频段发生了变化,单层涂层织物吸波频段主要为11.9-18 GHz,而三层涂层织物吸波频段在6.57-9.99 GHz之间。试验结果表明,在确定吸波涂层厚度和吸收剂比例前提下,涂层顺序的改变对织物吸波性有一定影响。1.2 mm的涂层厚度下,当涂层上层为PNAI、中层为Ba Fe₁₂O₁₉、底层为graphene时,涂层织物的吸波性能达到最佳,在9.53 GHz处的最小反射损耗RL值为-25.45 d B,平均吸收率可达86.69%。根据试验结论可知,通过涂层结构的设计可实现吸波频段的选择,这为材料吸波频段的可选择性提供实验基础。更多还原

【Abstract】 In the era of rapid development of information technology,electromagnetic wave,as the carrier of information dissemination,has been widely used in all aspects of life,and has made great contributions to the development of material civilization and social progress.At the same time,the environmental pollution caused by electromagnetic wave and the harm to human health cannot be ignored.Therefore,the research of absorbing materials has become a hot spot.At present,the common problem of absorbing materials is that it is difficult to take into account the four requirements of"light weight,wide frequency band,thin thickness and strong absorbing ability".In order to solve these problems,Ba Fe₁₂O₁₉,graphene,PANI were selected as absorbents to prepare multi absorbent single-layer and three-layer coated fabrics by mechanical mixing method.Based on the absorbing mechanism,the absorbing property of coated fabric is optimized by adjusting the ratio of absorbent and designing the coating structure.Finally,the thin flexible absorbing material with excellent absorbing property and bearing property is prepared.Firstly,pure phase Ba Fe₁₂O₁₉ with hexagonal sheet structure was prepared by microwave hydrothermal method,and microwave absorbing coated fabric was prepared with Ba Fe₁₂O₁₉as absorbent.When the coating thickness is 1.2 mm,the minimum reflection loss RL at 13.15GHz is-17.19 d B,the effective absorption bandwidth（RL﹤-10）is 1.22 GHz,and the average absorption rate is 37.21%.The single loss mechanism makes its absorbing effect poor,and the composite with graphene is used to make up for the problems of single loss mechanism,high density and poor impedance matching.Ba Fe₁₂O₁₉/graphene coated fabrics with five different mass ratios were prepared by tape casting.The experimental results show that when the thickness of the coating is 1.2 mm and the ratio of Ba Fe₁₂O₁₉ to graphene is 6:1,the microwave absorption performance is the best,the minimum reflection loss RL value can reach-36.83d B,the effective absorption bandwidth can reach 4.04 GHz,and the average absorption rate is78.79%.The absorbing performance is greatly improved.In order to further optimize the absorbing properties of the fabric,Ba Fe₁₂O₁₉/graphene/PANI single-layer coated fabrics with six different absorbent ratios were prepared by tape casting.When the coating thickness of the fabric is 1.2mm,the minimum reflection loss RL at 13.76GHz can reach-37.36,and the absorption bandwidth can reach 5.40 GHz.Due to the interaction and synergistic effect of the three-phase absorbents,the microwave absorbing properties of the fabric are further improved.The coating structure was designed to prepare Ba Fe₁₂O₁₉/graphene/PANI three-layer coating fabric.Compared with the single-layer coated fabric,the absorbing frequency band of the fabric has changed.The absorption band of single-layer coated fabric is mainly 11.9-18 GHz,while that of three-layer coated fabric is between 6.57-9.99 GHz.The experimental results show that the change of coating sequence has a certain influence on the microwave absorbing property of the fabric under the premise of determining the thickness of the absorbing coating and the proportion of absorbent.The absorbing property of the coated fabric with the 1.2 mm thickness of the coating is the best when the upper layer is PNAI,the middle layer is Ba Fe₁₂O₁₉,and the bottom layer is graphene.The minimum reflection loss RL at 9.53 GHz is-25.45d B,and the average absorptivity is 86.69%.According to the experimental results,the selection of absorbing frequency band can be realized through the design of coating structure,which provides an experimental basis for the selectivity of absorbing frequency band of materials.更多还原