共查询到18条相似文献,搜索用时 203 毫秒
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浸渍中间相沥青使炭/炭复合材料致密化1前言热固性树脂或煤焦油沥青被用作炭/炭复合材料[1]的基体前驱物,但它们的碳含量并不高。中间相沥青的碳含量高,且在高温下具有流动性,但在炭化过程中由于热解气体释出而大幅度膨胀。本文作者用炭纤维布和热固性树脂制造了... 相似文献
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将高温煤沥青和浸渍剂沥青在不同压力下炭化,在2500℃下对所得沥青炭进行石墨化处理;测试了所得沥青炭的体积密度、开孔率;利用扫描电子显微镜(SEU)观察了所得沥青炭的显微结构;利用XRD检测了所得沥青炭石墨化处理后的石墨化度;测试了所得沥青炭的压缩强度。结果表明:随着炭化压力的增大,沥青炭的体积密度增大而开孔率减小,压缩强度也随之增大;随着炭化压力的增大沥青炭显微结构呈由流线型向镶嵌型和域型转变的趋势;流线型结构沥青炭石墨化度较高,但也导致沥青炭的压缩强度降低。 相似文献
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炭化压力对沥青成焦形貌及航空刹车用C/C复合材料浸渍增密效果的影响 总被引:14,自引:6,他引:14
将武钢中温沥青和太钢高温沥青在不同压力下炭化,进一步对所得沥青焦进行了高温热处理,利用扫描电子显微镜(SEM)和光学显微镜观察所得沥青焦形貌。结果表明;低压炭化时,沥青焦体积密度小,疏松、多大孔,主要为流线区域型各向异性结构;高压炭化时,沥青焦体积密度明显变大,孔变小且均匀分布,主要为小区域和细镶嵌型各向异笥显微结构。考察了不同炭化压力对浸渍增密航空刹车用C/C复合材料的增密效率的影响,结果显示,对整个沥青而言的宏观残炭率明显高于只针对样品而言的实际残炭率,因此有必要进行高压浸渍/炭化实现快速增密。利用XRD和显微硬度测试仪检测了不同炭化压力所得沥青焦热处理后的石墨化度和显微硬度,发现高压下形成的沥青炭更难于石墨化,但石墨化度与显微硬度的热处理后的粗糙层(RL)CVD炭有较好的可比性。 相似文献
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煤焦油沥青对炭/炭复合材料成型和性能的影响 总被引:2,自引:0,他引:2
煤焦油沥青对炭/炭复合材料成型和性能的影响0引言用高压、高温浸渍工艺生产沥青基炭/炭复合材料减少了致密化循环次数,也提高了复合材料的最终密度。炭基体的微观结构极大地影响着复合材料的最终性能。反过来炭基体的微观结构又受到沥青前驱体物理—化学特性的影响。... 相似文献
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一、引言人们用热重分析仪研究了浸入炭电极中各种煤焦油沥青的热解。就沥青对浸渍过程的适用性而言,本文提供了一种评价其性能的技术。 相似文献
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高压浸渍-炭化制备炭/炭复合材料的组织结构 总被引:1,自引:1,他引:0
为研究高压浸渍-炭化制备的炭/炭复合材料的组织结构,以1 K PAN基高强度炭纤维为增强体,以调制中温煤沥青为基体前驱体,采用超高压浸渍-炭化工艺制备出2.5D沥青基炭/炭复合材料.采用偏光显微镜及SEM电镜对材料内部的组织形态进行了观察.研究表明:以中温沥青为基体前驱体所制备的炭/炭复合材料,在纤维束内,由于纤维之间的孔隙较小,形成的基体组织主要为镶嵌组织;而在纤维束之间,由于空间较大,出现的基体组织既有镶嵌型组织,也有域型组织.在沥青基炭基体中,有孔洞、裂纹、沟槽等缺陷. 相似文献
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为通过快速增密和低设备成本降低C/C复合材料的成本,采用中压浸渍、炭化多次循环的工艺制备了快速增密的C/C复合材料。该工艺以Z向增强的层叠炭布为增强体,不同软化点的中间相沥青和改性沥青为浸渍剂。考察了浸渍工艺,并研究了所得C/C复合材料的力学性能和断裂形貌。结果表明,中间相沥青及改性沥青等高残炭收率沥青是C/C复合材料极佳的浸渍剂,有利于快速增密。8次循环后(约2周时间),复合材料的密度从0.84g/cm^3增至1.76g/cm^3。炭布层叠Z向增强的C/C复合材料有良好的力学性能,而且其性能随着密度的增加而提高。所得复合材料的密度达到1.76g/cm^3时,拉伸强度为87.03MPa,弯强为113.56MPa,压缩强度为199.49MPa。 相似文献
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Ana Méndez Ricardo Santamaría Marcos Granda Rosa Menéndez 《Journal of Materials Science》2008,43(3):906-921
This article deals with the study of carbon composites behavior during their carbonization. Composites were prepared using
four granular carbons (graphite, anthracite, green petroleum coke, and foundry coke) and four pitches (a commercial impregnating
coal-tar pitch, an air-blown and two thermally treated pitches). The evolution of the optical microstructure, porosity, volume,
and weight of carbon composites was monitored at different intermediate carbonization temperatures (350, 500, 700, and finally
1000 °C). The porosity of composites increases with carbonization due to volume changes and weight loss of pitches. Weight
loss of carbon composites during their carbonization mainly depends on the pitch characteristics and it was slightly influenced
by the presence of granular carbon. On the other hand, carbon composites with the commercial coal-tar pitch and foundry coke,
anthracite, or graphite deform in the initial stages of carbonization (<350 °C) probably due to the lower porosity of the
green pellets and the high amount of low-molecular weight compounds of the pitch. Carbon composites with green petroleum coke
underwent important dimensional changes during their carbonization, expanding initially and then shrinking at temperatures
above 700 °C. The type of granular carbon strongly influenced the microstructure of the final carbon composite, as a result
of its effect on the development of mesophase. Graphite, anthracite and foundry coke delays mesophase development, whereas
green petroleum coke accelerates mesophase formation. 相似文献
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为了研究石油沥青(PP)作为煤沥青添加剂对沥青焦结构及导电性能的影响,将精制煤沥青(RCTP)与PP混合共炭化,同时在机械搅拌的作用下制焦,并对共炭化过程中PP和机械作用产生的影响机理进行了探讨和分析.采用偏光显微镜、X射线衍射仪、热重分析仪、比表面分析仪对所制半焦的结构进行了分析,利用电化学石英晶体微天平及电阻率仪对所制针状焦的性能进行了考察.结果表明:当PP质量分数为10%、搅拌速率为100 r/min、以间歇搅拌方式所制针状焦,其纤维组织占比达到了67.9%,电阻率降为676Ω·mm~2/m,即PP和机械搅拌二者联合作用存在下可显著增加中间相各向异性组织和纤维组织的含量,有利于改善半焦结构,使其结构更加趋于有序,所得针状焦电阻率也得到明显降低. 相似文献
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以高温煤沥青为浸渍剂,国产PAN基炭纤维编织的轴棒法预制体为增强材料,采用浸渍炭化致密工艺制备了沥青基炭/炭(C/C)复合材料,考察不同制备步骤下预制体致密效率的变化情况,并用扫描电子显微镜观察了C/C复合材料及基体炭的微观形貌。研究表明,随循环次数的增多,材料密度逐渐增大,密度增量逐渐减小;中间石墨化处理略微降低材料的密度,但材料的最终密度可大于1.90g/cm3。通过显微镜发现沥青基C/C复合材料内部在微观上仍存在少量裂纹和孔隙,基体炭的形态主要有区域型、流线型和镶嵌型。 相似文献
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Relationships between the characteristics of petroleum feedstocks and the graphitizability of the petroleum cokes 总被引:1,自引:0,他引:1
To clarify relationships between characteristics of raw materials and physical properties of derived petroleum cokes, studies are made of the carbonization of petroleum fractions and the graphitization of cokes made by pyrolysis in an autoclave under constant pressures. The coke derived from the saturate fraction which has a low aromaticity had a needle coke structure. The fluidity of carbonization processes is important in controlling the microscopic texture of coke. A relationship was obtained between the chemical structural parameters of the fractions and X-ray peak intensity of the graphitized cokes derived therefrom. It was shown that coke quality had a bearing on the number of condensed aromatic rings and the substituted side chain groups of the raw materials. 相似文献
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Sao Mochida You Qing Fei Takashi Oyama Yozo Korai Hiroshi Fujitsu 《Journal of Materials Science》1987,22(11):3989-3994
The carbonization of coal-tar pitches and their QI (quinoline insoluble)-free fractions was studied by evaluating their lump cokes produced in a tube bomb at various temperatures (470 to 550° C) and pressures (0 to 75 kg cm–2 gauge). The lump coke from QI-free fractions had a comparable anisotropic development and coefficient of thermal expansion (CTE). The carbonization temperature and pressure were found to influence strongly the properties of the cokes. At the highest temperature of 550° C, the most appropriate pressure for the best needle coke was 15 kg cm–2 G (gauge). Either higher or lower pressure increased the CTE value of coke. In contrast, at a moderate temperature of 500° C, the higher pressure produced the better coke. At the lowest temperature of 470° C, it took 10 h to complete the carbonization, and the lowest pressure allowed the best extent of uniaxial arrangement. Among the cokes prepared under the present conditions, the Carbonization at 500° C under 40 kg cm–2 G produced the best needle coke with a CTE value as low as 0.1 × 10–6° C–1. The carbonization scheme leading into the needle coke is discussed for a better understanding of how the carbonization temperature and pressure cooperatively influence the quality of the resultant coke, in relation to the carbonization reactivity of coal-tar pitch. 相似文献