Carbon
The structures of two types of mesophase pitch-based cal bon fibers (M30 and M70) reinforced SIC composites, prepared by the polycarbosilane impregnation-pyrolysis process, were investigated using transmission electron microscopy (TEM). It was found that M70 possessed a highly-ordered graphite structure despite occasional misorientation of some crystallites. However, the skin of M70 was less ordered than the interior of M70. The structure of M30 was uniform throughout, and was less ordered than that of M70. The fiber and matrix in M70/SiC bonded weakly, whereas the fiber and matrix in M30/SiC bonded tightly and locked together. This difference in. the interface feature originates from the difference of the surface crystalline structures of M30 and M70, and is formed during the first impregnation-pyrolysis cycle of polycarbosilane. (C) 1999 Elsevier Science Ltd. All rights reserved.
关键词:
carbon fibers, carbon composites;transmission electron microscopy;(TEM);microstructure;fiber
李宝华
,
王冠
,
翟登云
,
杜鸿达
,
康飞宇
新型炭材料
以中间相沥青(Mesophase pitch,MP)为前驱体、KOH作为活化剂,分别采用直接活化法、预炭化活化法制备出活性炭(Activated carbons,ACs).采用N2吸附法对所制ACs的比表面积、孔径分布进行分析.将所制ACs应用于电化学电容器电极材料,进行恒流充放电、循环伏安电化学分析.结果表明:电极的电化学性能不仅受活性炭比表面积、孔结构的影响,也与活性炭的微观形貌有关.其中预炭化活化法ACs颗粒具有片层结构,更有利于炭电极与电解液的浸润,提高微孔比表面积对比电容的贡献.
关键词:
中间相沥青
,
直接活化
,
预炭化活化
,
活性炭
,
孔结构
,
微观形貌
李伏虎
,
沈曾民
,
薛锐生
,
迟伟东
新型炭材料
doi:10.3969/j.issn.1007-8827.2004.01.005
为制备高性能中间相炭微球(Mesocarbon Microbeads,简称MCMB),选用三种不同中间相含量的石油渣油沥青为原料(中间相体积含量:PP1 85 %,PP2 90 %,PP3 100 %),采用乳液法制备中间相沥青微球(Mesophase Pitch Microbeads,简称MPMB),再经预氧化和炭化处理,制得圆整度好、收率高、球径分布窄的中间相炭微球.利用扫描电子显微镜(SEM)考察了MPMB的微观形貌,同时还利用激光粒度分析仪测定了MPMB的粒度分布.研究了乳液法制备MPMB的影响因素,研究结果表明:(1)耐高温硅油适宜作为乳液法的导热分散介质;(2)不同中间相含量的沥青制备微球时有其适宜的处理温度和时间(PP1:320 ℃,30 min;PP2:330 ℃,30 min;PP3:355 ℃,30 min),且制得的微球收率(收率:PP1〈PP2〈PP3)和微球形貌也有差异;(3)制备微球适宜的搅拌速度为900 r/min～1 200 r/min;(4)通过控制原料沥青颗粒度分布,制得了不同粒径分布的MPMB.
关键词:
乳液法
,
中间相沥青微球
,
中间相炭微球
,
导热分散介质
,
粒度分布
