熔盐辅助燃烧合成碳泡沫及其电磁屏蔽性能

Molten Salt-assisted Combustion Synthesis of Carbon Foam and its Electromagnetic Shielding Performance

以聚氯乙烯(PVC)为原料,金属镁粉(Mg)为还原剂,二茂铁(Fc)为催化剂,不同种类的熔盐(NaCl,KCl,MgCl2)为造孔剂,采用熔盐辅助燃烧合成法制备了碳泡沫。采用X射线衍射、扫描电子显微镜、Raman光谱仪、比表面积分析仪等对产物进行了表征;以燃烧合成的碳泡沫为吸收剂,石蜡为结合剂,采用矩形波导法测试试样在8.2~12.4 GHz频率范围内的电磁屏蔽效能。结果表明:使用NaCl熔盐作为造孔剂时发泡效果最好,燃烧合成产物经酸洗、水洗后得到发泡较为完整的圆球状碳泡沫,直径为100~500 nm;熔盐的加入有利于燃烧合成产物有序度的提高及泡沫形貌的改善,其中NaCl的促进效果最为显著。燃烧合成产物具有较好的电磁屏蔽性能,且在3种氯盐中,使用NaCl作为熔盐时产物的总电磁屏蔽效能最好,最高可达39.5 dB。

Carbon foams were prepared via molten salt-assisted combustion synthesis with polyvinyl chloride(PVC)as a carbon source,magnesium powder(Mg)as a reducing agent,ferrocene(Fc)as a catalyst and different kinds of molten salts(i.e.,NaCl,KCl,and MgCl2)as a porogen.The products were characterized by X-ray diffraction,scanning electron microscopy,Raman spectroscopy and specific surface area measurement.The electromagnetic shielding specimens were prepared with carbon foam as an absorbent and paraffin as a binder.The electromagnetic shielding effectiveness of the samples in the frequency range of 8.2-12.4 GHz was tested by a rectangular waveguide method.The results show that the optimum foaming effect is achieved when NaCl is used as a porogen,and the well-developed hollow spherical carbon foams with the pore sizes of 100-500 nm are obtained after washing and leaching.Molten salts have a positive effect on the graphitization degree and micro-morphology of carbon foams,in which NaCl shows an optimum accelerating-effect.The combustion synthesized products have a good electromagnetic shielding performance.The carbon foams with NaCl as a molten salt have an optimum electromagnetic shielding efficiency(i.e.,up to 39.5 dB).