碳磁异质结构吸收剂的设计、制备与电磁特性

发布时间：2018-01-13 14:08

本文关键词：碳磁异质结构吸收剂的设计、制备与电磁特性　出处：《浙江师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：理想的吸波剂要求质量轻,厚度薄,吸收强,频带宽,吸收频带可调及多功能性,传统的吸波材料难以满足当前民用和军用的高要求。目前,研究优良的吸波剂面临两大难题： (1)高吸收和阻抗匹配是矛盾体； (2)复合吸波剂的界面是影响性能的关键,但仍然难以控制。纵观前人的研究与吸波机理,将碳纳米管与纳米磁性金属复合成异质结构吸波剂可以摒弃传统单一碳材料和磁性金属材料吸波剂的自身限制,进而获得具有成分、结构和性能完全可控的新异质结构复合吸波材料。基于当前碳磁复合吸波材料的研究现状,本论文设计和制备了红毛丹状Ni/MWCNTs异质结构、蜈蚣状Fe/Fe3C/MWCNT异质结构和EG/Ni/MWCNT杂化异质结构三类杂化吸波材料,通过调节实验工艺条件,实现了成分、物相、形貌和性能的可控,深入地探究了异质结构吸波材料的形成过程及微波吸收机理。主要成果如下：(1)采用催化CVD法制备了形态和组成可控的红毛丹状Ni/MWCNT异质结构,详尽地研究了异质结构的静磁性能及微波吸收特性;研究发现,当PEG20000与NiO的投料比δ从3增到15,随着样品的C含量增加,形貌从Ni/C膜核壳结构演变为红毛丹状Ni/MWCNT异质结构；同时,δ的变化导Ms降低和介电常数增加,当δ=7.5时获得的Ni/MWCNT异质结构具有优异的吸波性能,其在12.8 GHz处有最小RL值为-37.9 dB,且在5.0至9.2 GHz内RL均低于-20 dB。(2)首次采用一种简便的气流诱导两步CVD法制备了成分和形貌可控的蜈蚣状Fe/Fe3C/MWCNTs异质结构,并且详尽地研究了该异质结构的静磁性能及微波吸收特性；蜈蚣状异质结构的形成归因于气流与自发磁化的协同作用；与Fe纳米纤维相比,蜈蚣状Fe/Fe3C/MWCN异质结构因其特殊的结构,具有多重共振特性、更高的介电损耗和微波吸收特性。(3)采用浸渍法和CVD法成功地制备了形态和成分可控的轻质EG/Ni/CNT杂化材料。研究了镍盐的浓度及不同碳源与前驱物比例对产物的组成、结构和形貌的影响。静磁和电磁特性的研究表明：控制Ni颗粒的含量、晶粒尺寸能有效地调节软磁和微波吸收特性。
[Abstract]:Ideal absorbent requires light weight, thin thickness, strong absorption, frequency bandwidth, adjustable absorption band and multifunction. Traditional absorbing materials are difficult to meet the high requirements of civil and military. There are two problems in the study of excellent absorbers: (1) High absorption and impedance matching are contradictions; The interface of composite absorbent is the key to influence the performance, but it is still difficult to control. The composite of carbon nanotubes and magnetic nanometallic materials to form heterogeneous structure microwave absorbers can abandon the limitations of traditional single carbon materials and magnetic metal materials and then obtain the components. Based on the current research status of carbon-magnetic composite absorbing materials, this paper designs and fabricates a novel red-wool Ni/MWCNTs heterostructure with completely controllable structure and properties. Three kinds of hybrid absorbing materials, centipede Fe/Fe3C/MWCNT heterostructure and EG/Ni/MWCNT hybrid heterostructure, were obtained by adjusting the experimental conditions. The morphology and properties are controllable. The formation process and microwave absorption mechanism of heterostructure absorbing materials are studied in depth. The main results are as follows: 1). Ni/MWCNT heterostructures with controllable morphology and composition were prepared by catalytic CVD method. The magnetostatic properties and microwave absorption characteristics of heterostructures are studied in detail. It is found that when the feed ratio 未 of PEG20000 to NiO increases from 3 to 15, the C content of the sample increases. The morphology changed from the core shell structure of Ni/C film to the Ni/MWCNT heterostructure. At the same time, the conductance Ms decreases and the dielectric constant increases. The Ni/MWCNT heterostructure obtained by 未 -7. 5 has excellent absorbing property. The minimum RL value at 12.8 GHz is -37.9 dB. Between 5.0 and 9.2 GHz, RL was lower than -20 dB. For the first time, a simple two-step CVD method was used to prepare the centipede-like Fe/Fe3C/MWCNTs heterostructure with controllable composition and morphology. The magnetostatic properties and microwave absorption characteristics of the heterostructure are studied in detail. The formation of centipede-like heterostructure is attributed to the synergistic effect of airflow and spontaneous magnetization. Compared with Fe nanofibers, centipede Fe/Fe3C/MWCN heterostructure has multiple resonance characteristics because of its special structure. Higher dielectric loss and microwave absorption. Lightweight EG/Ni/CNT hybrid materials with controllable morphology and composition were successfully prepared by impregnation and CVD. The concentration of nickel salt and the composition of the products with different carbon source to precursor ratio were studied. The effects of structure and morphology on the magnetostatic and electromagnetic properties show that the soft magnetic and microwave absorption characteristics can be effectively adjusted by controlling the content of Ni particles and grain size.
【学位授予单位】：浙江师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33;O611.3

【参考文献】