可膨胀石墨的制备及谱学特性研究

Preparation and study of spectra characteristics of expandable graphite

采用化学氧化法,以石墨粉(≤30μm)为原料,硫酸与高锰酸钾为氧化剂,以及磷酸为辅助插层剂制备出具有高膨胀体积的可膨胀石墨(EG)。通过XRD、Raman、SEM、EDS、FT-IR以及TG-DTA等测试手段对材料的微观结构、形貌、谱学特性及热稳定性进行表征分析。实验结果表明,当硫酸与磷酸体积比为2∶1时,EG氧化-插层效果最好,在400℃时膨胀体积达102ml/g。同时EG片层中含有P、S、Mn等元素,表明可能插入了磷酸、硫酸以及Mn的磷酸二氢盐、硫酸盐等物质。TG-DTA显示,EG的起始膨胀温度在160℃左右,且石墨在氧化-插层后,有序结构没有被完全破坏,部分石墨仍具有很好的耐热氧性。另外,探讨了EG可能的形成及膨胀机理。

In this work,the expandable graphite（EG） with high expanding volume has been successfully prepared by chemical oxidation method using graphite powders（≤30μm） as raw materials,H2SO4 and KMnO4 as oxidant,and H3PO4 as assisted intercalation agent.The micro-structure,morphology,spectral properties and thermal stability of the obtained products are characterized by XRD,Raman,SEM,EDS,FT-IR and TG-DTA.The experimental results show that the optimum volume ratio of H2SO4 and H3PO4 is 2∶1,while the swelling volume at 400℃ gets to 102ml/g.The elements such as P,S and Mn have been found in the layers of EG,therefore,there could be H3PO4,H2SO4,and dihydric phosphate ＆ sulphate containing Mn in the layers of EG.It is also demonstrated that the initial expanding temperature of EG is about 160℃ through TG-DTA curves.The ordered structure of graphite hasn＇t been absolutely destroyed after it is oxidized and intercalated,and part of EG sill has a good thermal stability under air atmosphere.In addition,the possible mechanism of EG formation and expansion has been discussed.