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### 碳化硅块状气凝胶的制备及应用

1. 海军工程大学动力工程学院 武汉 430033
• 收稿日期:2021-02-03 修回日期:2021-05-02 出版日期:2021-09-20 发布日期:2021-09-06
• 通讯作者: 杨自春
• 基金资助:
国家自然科学基金项目(51802347)

### Preparation and Applications of Silicon Carbide Monolithic Aerogels

Zhen Zhang, Shuang Zhao, Guobing Chen, Kunfeng Li, Zhifang Fei, Zichun Yang()

1. School of Power Engineering, Naval University of Engineering,Wuhan 430033, China
• Received:2021-02-03 Revised:2021-05-02 Online:2021-09-20 Published:2021-09-06
• Contact: Zichun Yang
• Supported by:
National Natural Science Foundation of China(51802347)

Silicon carbide aerogels have excellent properties such as high temperature stability, low thermal expansion coefficient, good thermal shock resistance, oxidation resistance and corrosion resistance, etc. They have great application potential in the fields of high temperature thermal insulation, electromagnetic wave adsorbing, filtration and adsorption under high temperature and high corrosive environment. However, the controllable preparation of bulk silicon carbide aerogels has always been a major challenge. As a new kind of aerogels, the preparation process of bulk SiC aerogels is more complicated than that of traditional oxide and carbon aerogels. In recent years, the research on preparation and application of SiC aerogels has entered a new stage. Many new strategies for preparing SiC aerogels have been developed, and many important progress has been made in the research of SiC aerogels in the fields of heat insulation and electromagnetic wave adsorbing. In this paper, the research progress on preparation and application of monolithic silicon carbide aerogels is reviewed. Firstly, the advantages and disadvantages of various preparation technologies are analyzed and summarized, including carbon thermal reduction method with organic/SiO2 composite aerogels, cracking method with pre-ceramic polymer, chemical vapor deposition method, high-temperature vapor-phase silicon cementation method and self-assembly method of SiC nanowire. Then the application research progress of SiC aerogel in high temperature insulation and electromagnetic wave adsorbing are introduced in detail. Finally, the development trend of SiC aerogel in the future is prospected.

Contents

1 Introduction

2 Preparation of SiC aerogels

2.1 Carbon thermal reduction of organic/SiO2 composite aerogels

2.2 Cracking of pre-ceramic polymer

2.3 Chemical vapor deposition

2.4 High-temperature vapor-phase silicon cementation

2.5 Assembly of SiC nanowire

3 Applications of SiC aerogels

3.1 High-temperature thermal insulation

3.3 Other applications

4 Conclusion and outlook

()

Fig.1 Flow chart of the SiC aerogel preparation[14]

Fig.2 (a) Photograph, (b) SEM image, (c) TEM image, (d) HRTEM image of SiC aerogels. Insets in (c): SAED patterns[59]

Fig.3 Macro and micro characters of the SiC NWAGs. (a) SiC NWAG with density of about 3 mg·cm-3 on the stamen of a peach blossom. (b) Large-size SiC NWAG tube and column with density of about 11 mg·cm-3. (c) SiC NWAGs with different shapes on the leaves of a plant. (d) and (e) SEM images of the SiC NWAG with different magnifications showing the network with numerous highly entangled SiC nanowires. Inset in (d) showing the EDS of nanowires. (f) TEM image with the insets showing corresponding HRTEM image and SAED pattern[61]

Fig.4 Schematic of the formation of RF/SiO2 gels and SiC aerogels[47]

Fig.5 Fabrication process and overview of the mechanical performance and fire resistance of the SiC@SiO2 aerogel. (A) Fabrication process of the AH-SSCSNWA. (B) Photograph of a piece of the AH-SSCSNWA with a volume of ~15 cm3, standing on a leaf, indicating its ultralow density. (C) Photograph showing that a 20 g weight can be supported by a piece of the AH-SSCSNWA with a weight of 5 mg, demonstrating the high stiffness of the AH-SSCSNWA. (D) Vertical burning test showing the good fire resistance of the AH-SSCSNWA[103]

Fig.6 Thermal insulation performance and fire erosion resistance of the SiC NWAGs. (a) Thermal conductivities of the SiC NWAGs as a function of density. (b) Insulation behavior (density 5 mg·cm-3) and (c) resilience of SiC NWAG under alcohol lamp and butane blowtorch flame, respectively. (d) Optical and (e)~(h) infrared images of SiC NWAG with density of 11 mg·cm-3 exposed to a butane blowtorch flame for 1000s. (i) Time-dependent temperature evolution of three reference points on the back side of the SiC NWAG. (j) Optical images of the sample before and after butane blowtorch flame erosion. (k) SEM image of SiC NWAG after the butane blowtorch flame erosion. (l) Thermal conductivities at room temperature in air versus maximum working temperature for aerogel-like materials.[61]

Fig.7 EMI shielding efficiency of samples: (a) dense SiC ceramic and (b) hierarchical porous SiC foam. (c) Specific EMI SE of dense SiC ceramic and hierarchical porous SiC foam at 11 GHz and (d) proposed EMI shielding mechanism are also shown[94]

Fig.8 Schematic illustration of the preparation process for SiC nanowire nonwoven fabric. (1) The first stage is growth of SiC nanowires on carbon fiber, (2) the second is the formation of the ultralong SiC nanowire felt, and (3) the third is the fabrication of SiC fabric by the compression of ultralong SiC nanowire felt. (a) Carbon fiber, (b) SiC nanowires grown on carbon fiber, (c) SiC nanowire mat, (d) SiC fabric[117]