| YE Zheng-wei,ZHAO Qi-zhi,WANG Ke-jun,LI Xiao-qiong,YANG Jian-jian.Preparation and Electromagnetic Wave Absorbing Properties of Light Magnetic Carbon Aerogel[J],52(8):397-405 |
| Preparation and Electromagnetic Wave Absorbing Properties of Light Magnetic Carbon Aerogel |
| |
| View Full Text View/Add Comment Download reader |
| DOI：10.16490/j.cnki.issn.1001-3660.2023.08.035 |
| KeyWord:carbon aerogel ferroferric oxide particle size electromagnetic wave absorbing material impedance matching |
| Author | Institution |
| YE Zheng-wei |
Chemical Defense Research Institute, Academy of Military Sciences, Wuhan , China |
| ZHAO Qi-zhi |
Chemical Defense Research Institute, Academy of Military Sciences, Wuhan , China |
| WANG Ke-jun |
Chemical Defense Research Institute, Academy of Military Sciences, Wuhan , China |
| LI Xiao-qiong |
Chemical Defense Research Institute, Academy of Military Sciences, Wuhan , China |
| YANG Jian-jian |
Chemical Defense Research Institute, Academy of Military Sciences, Wuhan , China |
|
| Hits: |
| Download times: |
| Abstract: |
| With the rapid spread of wireless communication devices using electromagnetic waves in the range around GHz, several problems such as electromagnetic interference and information leakage have emerged and need to be solved. Microwave absorption materials can absorb electromagnetic waves effectively and convert electromagnetic energy into thermal energy, thus are highly demanded to eliminate adverse electromagnetic waves effectively in electronic safety, and national defense security. Porous carbon materials are always employed to absorb microwave energy due to the very large surface area and great potential for further functionalization. In this paper, ferrite/carbon aerogel composites were fabricated to endow the carbon aerogel magnetic property and also lower density of composites. First, Fe3O4 particles of different sizes were prepared by a simple co-precipitation (using sodium hydroxide or ammonia as co-precipitator) through controlling the Fe ions concentration of the reaction system. Then the aqueous solution of Fe3O4 modified by CTAB was prepared and added to the resorcinol- formaldehyde sol. After sufficient mixing, the solution was left to gel by elevating the temperature and supercritical drying subsequently. The final magnetic carbon aerogel composites were obtained by pyrolysis of the organic polymeric aerogel at 690 ℃. SEM (FEI Company Sirion200) and TEM (Japan Electronics Corporation JEM-1400Plus) were used to characterize the Fe3O4 particle size and microstructure of the composites. A laser particle size analyzer (Malvern Company Zetasizer Nano ZSP) was used to characterize the particle size and distribution of the Fe3O4 particles. The surface area and pore size of the magnetic carbon aerogels were characterized by a specific surface and micropore analyzer (BSD-PM). The static magnetic properties of the materials were characterized by a vibrating sample magnetometer (Lake Shore model 7 404G). The complex permeability and permittivity of materials were measured with a N5 230A vector network analyzer by coaxial wire method over the frequency range of 2~18 GHz. The results showed that, Fe3O4/carbon aerogel composites had rich three-dimensional network structure, and carbon aerogel provided a large contact surface for individual and uniform dispersion of well-adhered Fe3O4 particles on it. Fe3O4/CA had typical ferromagnetic properties, and the saturation magnetization of Fe3O4/CA increased as the Fe3O4 particle size decreased. The saturation magnetization of 75 nm-Fe3O4/CA was the largest, reaching 29.26 emu.g–1. When the size of incorporated Fe3O4 particle was 330 nm, the minimum reflection loss value of the composite was only –10.61 dB, and the microwave absorption performance was poor. When the particle size of Fe3O4 was 75 nm and the thickness of the composite was 2.1 mm, the minimum reflection loss value could reach –52.43 dB at 17.15 GHz. When the particle size of Fe3O4 was 120 nm, the effective absorption bandwidth of the composite at the thickness of 2.5 mm could reach 6.98 GHz (10.97~17.95 GHz). The mechanism of the microwave absorption of Fe3O4/carbon aerogel composites could be concluded by following:firstly, carbon aerogel acting as perfect 3D substrate provides a large specific surface area for the dispersion of Fe3O4 particles, which gives rise to dielectric loss and magnetic loss respectively and makes the hybrid perform better microwave absorption properties. Secondly, the microwave absorption capability can be attributed to a strong conductivity loss, and it can be optimized by phase component and microstructure with an interfacial polarization capability. When the particle size of Fe3O4 is small, the complex dielectric constant of the composites is relatively large. However, when the particle size of Fe3O4 is large, the three-dimensional conductive network structure of carbon aerogel would be destroyed by the large Fe3O4 particles, which will reduce the dielectric loss ability of the composite. In addition, the porous structure could prolong the propagation paths for electromagnetic wave reflection and scattering in the composites. |
| Close |
|
|
|