以煤焦油沥青为原料,鳞片石墨为添加剂,在410℃温度下反应7h制得了中间相炭微球(MCMBs).在扫描电子显微镜下对它们的表面和断面进行了分析,并用X射线衍射对其结构进行了研究.结果表明:MCMBs的表面被接近球形的小颗粒所覆盖而呈现出粗糙不平.MCB1(未加石墨)的织构主要是平行层型,而MCB2(加石墨)的织构却是复杂的.加入煤焦油沥青中的大片石墨存在于MCMBs的中心而被认为是它们的核,而小片石墨却不能象大片石墨那样在反应体系内充当核的作用.认为在成核过程中,大片石墨聚集到一起而形成晶种,同时一些低分子量的沥青组分被包裹在这些晶种的内部,石墨片以及它们的积聚体的形状、大小决定了MCMBs的织构.然而,小石墨片只能使MCMBs的织构变得杂乱.MCMBs的XRD谱图表明石墨的添加改变了其结构,并降低了它的石墨化能力和晶体大小 .
Mesocarbon microbeads (MCMBs) were prepared from a coaltar pitch without or with flake-like graphite at 410℃ for 7h. The a s-received MCMBs were named MCB1 and MCB2 respectively and the MCB2 was divided into MCB2L and MCB2S according to the size of the flakes of graphite added. The surface and cross-section of MCMBs were studied using SEM and the microtexture was analyzed by XRD. The surface of the MCMBs was rough with some particles att ached and the beads are almost round. The microtexture of MCB1 (without graphite) was mainly of the parallel layer type, whereas the microtexture of MCB2 (with graphite) was complex. The large flakes of graphite added in the coal tar pitch were regarded as the centers of nucleation of MCMBs, resulting in hamburger type MCMBs (MCB2L), but the small ones could not act in this way in the reaction sys tem, resulting in a distorted microtexture (MCB2S). It was proposed that when th e nucleation occurred the large graphite flakes accumulated to form seed crystal sin which the pitch components with low molecular weight were enwrapped and the shape and size of the flakes and their aggregations decided the microtexure of MCMBs, while the small graphite flakes served only to disorder the microtexture. The XRD spectra show that the addition of graphite decreased the graphitization degree and crystal sizes.
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