【作者】 杨磊；

【导师】 杜耘辰；

【作者基本信息】 哈尔滨工业大学 ， 化学， 2020， 硕士

【摘要】 在当今多元化的时代,我们的生活中出现了各种各样的高科技产品,这些高科技产品在使用的过程中会向我们生存的空间环境中辐射电磁波,从而产生电磁污染问题。电磁波吸收材料能够有效地解决电磁污染问题,电磁波损耗机制包括介电损耗机制和磁损耗机制,将磁性材料与碳材料进行复合可制备两种损耗机制兼备的复合材料。本论文将磁性金属与碳材料进行复合,利用高温热解法制备三维网状的磁性碳基复合材料,研究了材料的不同化学组成对电磁波衰减能力的影响,通过调控碳纳米管的沉积量调节复合材料的介电性能,进而优化材料的吸波性能。利用金属硝酸盐热解产生气体来形成三维多孔空腔碳骨架结构,成功制备了三维网状的Ni/C-X复合材料。三维网状的多孔空腔结构存在多重反射机制,能够延长电磁波与材料间的反复振荡作用时间,通过改变与聚乙烯吡咯烷酮(PVP)的质量比从而改变最终三维网状Ni/C-X复合吸波材料中磁性金属与碳组分的比例,研究表明,当Ni(NO3)2·6H2O与PVP的质量投料比为1:1时,样品Ni/C-1具有最优异的吸波性能,即样品Ni/C-1在厚度为1.7 mm时,最大反射损耗在18.0 GHz处,其数值为-20.7 d B。当Ni/C-1复合材料厚度在2.0 mm时,有效带宽为5.2 GHz(12.8 GHz-18.0 GHz)。为了进一步优化Ni/C-X复合材料的电磁波吸收性能,将三聚氰胺作为碳源,利用气相沉积法在Ni/C-1复合材料上负载碳纳米管,得到Ni/C/CNTs-X复合材料。通过调控碳纳米管的沉积量来对材料进行改性,石墨化的碳纳米管可以有效的改善材料的阻抗匹配能力。研究表明,三聚氰胺与三维网状Ni/C复合材料的质量比为6:1时,即样品Ni/C/CNTs-2复合材料具有相对较好的吸性能。样品Ni/C/CNTs-2在厚度为3.4 mm时,最大反射损耗在6.6 GHz处,其数值为-69.3 d B。当Ni/C/CNTs-2复合材料厚度在1.8 mm时,有效带宽为5.6 GHz(12.4 GHz-18.0 GHz)。该研究为碳基磁性吸波材料的研究在结构构建和组分设计上提供了重要的研究思路。更多还原

【Abstract】 In today’s era of pluralism,we have a variety of high-tech products in our life,these high-tech products in the process of use will radiate electromagnetic waves to our living space environment,resulting in electromagnetic pollution problems.Electromagnetic wave absorption materials can effectively solve the problem of electromagnetic pollution.The mechanism of electromagnetic wave loss mainly depends on the mechanism of dielectric loss and magnetic loss.The composite of magnetic materials and carbon materials can have both dielectric loss and magnetic loss properties.It can also better meet the characteristics of the new absorbing materials "thin,light,wide and strong ".In this paper,magnetic metals are combined with carbon materials,and three-dimensional reticular magnetic carbon matrix composites are prepared by high temperature pyrolysis.The effects of different chemical compositions of the materials on the attenuation ability of electromagnetic waves are studied.The dielectric properties of the composites are adjusted by regulating the deposition of carbon nanotubes,and then the absorbing properties of the materials are optimized.Three-dimensional(3D)mesh Ni/C-X composite was successfully prepared by using metal nitrate pyrolysis to produce gas to form a 3D porous cavity carbon skeleton structure.The 3D reticulated porous cavity structure has multiple reflection mechanism,which can prolong the time of repeated oscillation between electromagnetic wave and material.By changing the mass ratio of Ni(NO3)2·6H2O to PVP,the ratio of magnetic metal to carbon component in the final three-dimensional reticulated Ni/C-X composite absorbing material is changed.The results show that the sample Ni/C-1 has the most excellent absorbing property when the mass feeding ratio of Ni(NO3)2·6H2O to PVP is1:1,that is,the maximum reflection loss is 18.0 GHz,the value is-20.7 d B.The effective bandwidth is 5.2 GHz(12.8 GHz-18.0 GHz)when Ni/C-1 composite thickness is 2.0mmIn order to further optimize the electromagnetic wave absorption performance of Ni/ C-X composites,based on the three-dimensional porous Ni/C-1 composites,the carbon nanotubes were loaded on the three-dimensional porous Ni/C-1 composites by vapor deposition method to improve the wave absorption performance of the materials.Melamine was used as the carbon source,and the amount of carbon nanotubes loadedwith three-dimensional carbon skeleton was adjusted by adjusting the amount of melamine added.By regulating the amount of carbon nanotubes deposited to modify the material,graphitic carbon nanotubes can effectively improve the impedance matching ability of the material.The study showed that the optimal feeding ratio of melamine to three-dimensional reticulated Ni/C skeleton was 6:1.In other words,Ni/C/CNTs-2composites have excellent electromagnetic wave absorption performance.When the thickness of Ni/C/CNTs-2 is 3.4 mm,the maximum reflection loss is 6.6 GHz,and the value is-69.3 d B.The effective bandwidth is 5.6 GHz(12.4 GHz-18.0 GHz)when Ni/C/CNTs-2 composite thickness is 1.8 mm.This study provides an important idea for the study of carbon-based magnetic absorbing materials in structure construction and component design.更多还原