炭化压力对石墨化沥青焦微观结构的影响

Effects of Carbonization Pressure on Microstructure of Graphitized Pitch-derived Carbons

以高温煤沥青为原料,分别在30MPa和60MPa炭化压力下制备了石墨化沥青焦,研究了两种炭化压力下制备的石墨化沥青焦的微观结构.结果表明:30MPa所制备试样的流线/流域型组织占优,60MPa制备试样的流域型和镶嵌型组织占优.流线型和流域型结构是易石墨化结构,镶嵌型结构是难石墨化结构.炭化压力对沥青焦微观结构的影响主要是通过影响中间相的成核、生长和融并来实现的,30MPa炭化压力下,中间相小球融并完全,因而形成各向异性流线型结构;60MPa炭化压力下,中间相小球融并受阻,从而形成镶嵌型结构.TEM和SAED分析表明:30MPa制备的石墨化沥青焦以高度取向的流线型组织为主,在片层边缘及片层之间存在各向同性组织;60MPa制备的石墨化沥青焦为多种微观组织并存,分布不均匀,除各向同性组织外,沥青焦微观组织选区电子衍射图谱的(002)环不同程度呈点状分布.以上现象说明30MPa制备的石墨化沥青焦微观组织的均匀性和取向性都要好于60MPa制备的石墨化沥青焦.

Graphitized pitch-derived carbons were prepared under carbonization pressures of 30MPa and 60MPa respectively,using high temperature pitch as raw material.Microstructure of the samples were investigated by SEM and TEM.Results indicate that the samples prepared at 30MPa and 60MPa are dominated by easy graphitized flow/flow domain type texture and non-graphitized mosaic/domain type texture,respectively.Nucleation,growth and amalgamation of carbonaceous mesophase spherule as well as microstructures of as-prepared materials are influenced by carbonization pressures.Carbonaceous mesophase spherule can amalgamate completely to form anisotropic flow type texture at the carbonization pressure of 30MPa,while amalgamation of carbonaceous mesophase spherule is blocked to form mosaic type texture at the carbonization pressure of 60MPa.TEM and SAED results show that main texture of the sample prepared at 30MPa is flow type texture,some isotropic textures exist at the rim of lamellar structures or among them.Samples prepared at 60MPa exhibit non-homogeneous microstructure where（002） rings distribute by spotted state.It can be concluded that uniformity and orientation of the sample prepared at 30MPa are better than those of the sample prepared at 60MPa.