论文总字数：18986字

摘 要

随着电子信息技术的迅猛发展，高速飞行器因长时间受气动加热而在表面产生异常高温，其中的高温特殊部件直接暴露在探测雷达波下，极易被雷达发现，因此，迫切需要一种能够耐高温隐身性能的先进材料。研发具有密度低、耐高温、抗氧化能力强以及吸波性能优异的吸波材料具有重要的科学意义和军事应用前景。SiC基泡沫作为一种极具前途的高温隔热材料，同时也是一种优异的介电损耗型吸波材料，具有独特的温度变化属性，其温度越高，吸波性能越好，已成为高温吸波材料中的研究重点。

本实验采用CVD工艺，以三聚氰胺泡沫碳化而成的超轻碳泡沫为模板，在制备出SiC骨架网络基础上进一步基于V-L-S（气-液-固）生长机制，于SiC骨架表面原位生长SiC纳米线（SiC_nw），最后通过氧化去除模板C骨架，从而得到一种具有中空骨架的超轻SiC泡沫/SiC_nw复合材料。极高的孔隙率使得材料与空气界面具有良好的阻抗匹配性，高度发达的SiC网络有助于渗透电磁波多重散射吸收效应，同时中空SiC骨架结构和SiC_nw界面及其中的堆叠缺陷和异质结可进一步增强了电磁波能量的耗散，协同提升超轻SiC_nw/SiC_foam复合材料吸波性能。

通过电镜观察制备得到的超轻SiC_nw/SiC_foam复合材料，SiC_nw的嵌入将显著提高材料的比表面积和界面结构，有助于材料吸波性能的提升。基于前期资料对实验结果进行预测，通过加入Ni(NO₃)₂催化剂，可在SiC泡沫内部基于V-L-S（气-液-固）机制生长SiC_nw，从而制得不同纳米线含量的超轻SiC_nw/SiC_foam复合材料，复合之后材料的吸波性能会有显著提高，并随着SiC_nw含量的增大而增大，但随着SiC_nw含量的进一步增加，吸波性能会有所降低。

关键词：超轻 SiC纳米线 化学气相沉积 SiC泡沫 吸波材料

Preparation and Absorbing Properties of SiC nanowires composite ultra-light SiC foam

Abstract

With the rapid development of electronic and information technology, high-speed aircrafts have been subjected to aerodynamic heating for a long time, resulting in abnormal high temperature on the surface. The special parts of the high temperature are directly exposed to the detection radar waves and are easily detected by radar, there is an urgent need for an advanced material with high temperature resistance and stealthy performance. The research and development of microwave absorbing materials with low density, high temperature resistance, oxidation resistance and excellent microwave absorbing properties have important scientific significance and military application prospects. As a promising high temperature insulation material, SiC based foam is also an excellent dielectric loss absorbing material, which has a unique property of temperature change. The higher the temperature, the better the absorbing property, it has become the research focus of high temperature absorbing materials.

In this experiment, SiC nanowires (SiC_nw) were grown in situ on the surface of SiC framework by using CVD technique and ultralight C foam formed by carbonization of Melamine Foam as template, on the basis of V-L-S (gas-liquid-solid) growth mechanism, finally, an ultra-light SiC_nw/SiC_foam composite with hollow skeleton was obtained by removing the template C skeleton by oxidation. The extremely high porosity makes the material have a good impedance matching with the air interface.The highly developed SiC network helps to penetrate the multi-scattering absorption effect of electromagnetic waves. At the same time, the hollow SiC framework, the SiC_nw interface, the stacking defects and the heterojunction can further enhance the electromagnetic wave energy dissipation, and enhance the microwave absorbing properties of the ultra-light SiC_nw/SiC_foam composites.

The SiC_nw/SiC_foam composites were prepared by SEM.The specific surface area and interface structure of the composites were improved by SiC_nw intercalation, and the microwave absorbing properties were improved. Based on the previous data, the experimental results were predicted. By adding Ni (NO₃)₂ catalyst, the SiC_nw/ultra-light SiC_nw/SiC_foam composites with different nanowire content were prepared by the growth of SiC_nw based on V-L-S (gas-liquid-solid) mechanism in SiC foam, the microwave absorbing properties of the composite will be improved obviously, and increase with the increase of SiC_nw content, but decrease with the increase of SiC_nw content.

Key words: ultra-light；SiC Nanowires；CVD；SiC Foam；Absorbing Material

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1引言 1

1.2吸波性能简介 2

1.2.1吸波材料具有的特性 2

1.2.2吸波材料及吸波机理 2

1.3碳泡沫吸波材料介绍 3

1.3.1超轻碳泡沫的结构性质 3

1.3.2超轻碳泡沫的微波吸收性能 4

1.4 SiC_nw介绍 4

1.4.1 SiC_nw的制备 4

1.4.2 SiC_nw的吸波性能 4

1.4.3 SiC_nw的吸波机理 4

1.5课题的提出及研究思路 5

第二章 实验过程与方法 6

2.1实验原料 6

2.2实验设备 6

2.3实验流程 7

2.4实验方案设计 8

2.4.1 柔性碳泡沫的制备 8

2.4.2 超轻SiC泡沫的制备 8

2.4.3 制备具有中空骨架的超轻SiC泡沫 9

2.4.4 超轻SiC_nw/SiC_foam复合材料的制备 9

2.5表征方法 9

2.5.1 X射线衍射分析 9

2.5.2扫描电子显微分析 9

2.5.3透射电子显微镜分析 10

2.5.4矢量网络分析仪测试 10

第三章 结果与讨论 11

3.1物相分析 11

3.2超轻SiC_nw/SiC_foam复合材料的微观形貌 12

3.3超轻SiC_nw/SiC_foam复合材料吸波性能研究 14

3.4超轻SiC_nw/SiC_foam复合材料的吸波机理研究 16

第四章 结论 17

参考文献 18

致谢 21

第一章 绪论

1.1引言

随着电子信息技术的迅猛发展，人们在生活中使用电子信息产品的频率越来越高。使用电子信息产品固然会为我们的生活带来更多的便利，但是在使用电子产品时会产生许多的电磁辐射，这些电磁辐射会对人们的身体健康^[1]和电子设备的运行产生不利影响^[2]。在这种情况下，研制出吸波性能良好的新型材料已成为目前材料研究的一个重要方向。在军事领域，高速飞行器因长时间受气动加热而在表面产生异常高温，其中的高温特殊部件直接暴露在探测雷达波下，极易被雷达发现，因此，迫切需要一种能够耐高温隐身性能的先进材料。吸波材料除了具备有良好的吸波性能外还需要具有一些其他的良好的性能如密度小，耐高温，抗腐蚀等性能。^[3]

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