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
In-Young Yang
,
Kwang-Hee Im
,
Uk Heo
,
David K Hsu
,
Je-Woong Park
,
Hak-Joon Kim
,
Sung-Jin Song
材料科学技术（英文）
CFRP (carbon fiber reinforced plastics) composite materials have wide applicability because of their inherent design flexibility and improved material properties. However, impacted composite structures have 50%–75% less strength than undamaged structures. In this work, a CFRP composite material was nondestructively characterized in order to ensure product quality and structural integrity of CFRP and one-sided pitch-catch technique was developed to measure impacted-damaged area by using an automated-data acquisition system in an immersion tank. A pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave under defect conditions in the composite.
关键词:
Impact damages
,
null
,
null
,
null
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
Shiushichi Kimura
,
Kouichi Yasuda
,
Yohtaro Matsuo
,
Aira Hotta
材料科学技术（英文）
Theoretical consideration was conducted on a relation between pore diameter and interfacial area between pores and fibers when pores uniformly distribute in C/C composites. It was shown that bonding at the fiber/matrix interface apparently decreased with decreasing a pore diameter, and consequently a new idea of microspace modification concept was proposed for controlling fracture behavior of C/C composites. Four types of C/C composites with various pore structures were fabricated by hot-pressing, and their fracture behavior was investigated by three point bending tests. The fracture behavior of the C/C composites was changed from brittle one to pseudo ductile one with decreasing the pore diameter. This result supported the validity of the microspace modification concept proposed in this paper.
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