镁热反应制备介孔非均质SiO_(2)@SiC@C微球的吸波性能研究

Microwave Absorbing Properties of Mesoporous Heterogeneous SiO_(2)@SiC@C Microsphere Prepared by Magnesiothermic Reaction

以改良Stober法合成的介孔SiO_(2)为前驱体,通过自组装技术在SiO_(2)表面包覆酚醛树脂,碳化后形成SiO_(2)@C,再经800℃镁热反应得到形貌均匀的介孔非均相SiO_(2)@SiC@C微球,并利用XRD、XPS、Raman、BET、SEM和TEM对SiO_(2)@SiC@C进行表征/分析。结果表明,SiO_(2)@SiC@C微球由SiC、非晶SiO_(2)、非晶C和SiO_(x)C_(y)相组成,且表面存在大量介孔结构。介孔非均相SiO_(2)@SiC@C微球展现出优异的吸波性能,当模拟匹配厚度为2 mm时,最小反射损耗在17.74 GHz处达到-36.83 dB,当模拟匹配厚度为2.5 mm时,最大吸收带宽达到了6.63 GHz,完全覆盖了Ku段,表现出强吸收、宽频段的性能,这是介孔结构优化阻抗匹配和非均质界面增强界面极化协同作用的结果。本文制备的介孔非均相SiO_(2)@SiC@C微球可满足电磁波吸收防护领域的应用需求。

The mesoporous SiO_(2)synthesized by modified St ber method was used as precursor.The phenolic resin was coated on the surface of SiO_(2)by self-assembly technology and SiO_(2)@C was formed after carbonization.The mesoporous heterogeneous SiO_(2)@SiC@C microspheres with uniform morphology were obtained by magnesiothermic reaction at 800℃.As shown in the characterization results of XRD,XPS,Raman,BET,SEM and TEM,the SiO_(2)@SiC@C microspheres were composed of SiC,amorphous SiO_(2),amorphous C and SiO_(x)C_(y)phases,and a large number of mesoporous structures can be found on the surface.The mesoporous heterogeneous SiO_(2)@SiC@C microspheres exhibit excellent microwave absorption performance in the simulation results of microwave absorption performance.When the simulated matching thickness is 2 mm,the minimum reflection loss reaches-36.83 dB at 17.74 GHz.The maximum absorption bandwidth reaches 6.63 GHz at the simulated matching thickness of 2.5 mm,completely covering the Ku band.The mesoporous heterogeneous SiO_(2)@SiC@C microspheres show strong absorption and wide frequency band.This is the result of the synergistic effect of mesoporous structure optimizing the impedance matching and heterogeneous interface enhancing the interface polarization.The mesoporous heterogeneous SiO_(2)@SiC@C microspheres prepared in this experiment can meet the application requirements in the field of electromagnetic wave absorption protection.