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结构炭/炭复合材料力学性能及微观结构研究 总被引:13,自引:1,他引:13
采用四向编织、快速化学气相渗透致密化新工艺制备了炭/炭复合材料,其弯曲强度达320MPa。分析研究了这种材料的力学性能特征。利用SEM和高分辨TEM分析了基体炭、炭纤维/基体灰界面的精细结构,发现炭纤维呈单根被基体炭包围,基体现灰呈层片状,为二维有序的乱层石墨结构;在炭纤维与基体炭之间存在着过渡相,这一过渡相厚度的约几十纳米,随着与炭纤维之间距离的增大,它们之间形成的夹角由小变大,这一过渡相即为炭 相似文献
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热梯度CVI制备炭/炭复合材料及其研究进展 总被引:1,自引:0,他引:1
按预制件内部的温度分布不同,可以认为,均热法及热梯度法是化学气相沉积制备炭/炭复合材料的两种基本工艺。对于圆筒或圆盘形工件,热梯度CVI具有增密快,炭的有效利用率高,可实现工业规模化生产的优点,是一种很有前景的CVI工艺。本文介绍了热梯度CVI制备炭/炭复合材料的工艺原理、工艺特点及其最新研究进展。 相似文献
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对同一种炭/炭复合材料,经过不同温度热处理后的微观结构、石墨化度、导热系数、抗弯强度和摩擦磨损性能进行了对比研究。试验表明:随着最终热处理温度的提高,易石墨化的热解炭偏振光下光学活性增强,而难石墨化的热解炭微观结构几乎没有变化;炭/炭复合材料的晶粒逐渐长大,层面间距缩小,石墨化度有较大提高;平行炭布方向的导热系数和垂直炭布方向的导热系数均有上升。同时,由于基体炭与炭纤维两者热膨胀系数的差别,热处理温度的提高,降低了基体与增强纤维的的结合强度,使炭/炭复合材料的抗弯强度降低。试验还表明:随着热处理温度的提高,炭/炭复合材料的摩擦表面逐渐形成薄而致密的自润滑膜,摩擦系数在经过一个峰值后趋于平稳状态,磨损量下降明显。经l800℃热处理的质量损失主要是由氧化造成的。 相似文献
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高温热处理对炭 /炭复合材料湿态摩擦性能的影响 总被引:2,自引:1,他引:2
研究了高温热处理工艺对快速定向扩散化学气相渗透炭/炭复合材料在湿态下的摩擦磨损性能的影响。实验选择了4种不同的高温热处理工艺,用于比较其对炭/炭复合材料微观结构及湿态下的摩擦磨损性能的影响。分析结果表明湿度对炭/炭复合材料的摩擦性能有显著的影响,在湿态下它的摩擦系数明显低于正常干态下的摩擦系数并且随着刹车压力和刹车惯量的增加下降得更快;高温热处理工艺对炭/炭复合材料微观结构有显著影响,通过改变炭/炭复合材料微观结构,适当的高温热处理工艺可以改善湿态下炭/炭复合材料摩擦磨损性能。结果表明,最适合的热处理温度为2000℃,在2000℃下热处理的炭/炭复合材料有足够的摩擦系数,并且湿度对其摩擦磨损性能影响较其他3种热处理工艺的炭/炭复合材料小。 相似文献
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四种用于制备炭/炭(C/C)复合材料的预制体,即1K发布叠层坯体(1#坯体),3K发布叠层坯体(4#坯体),发市 炭纸叠层坯体(2#坯体),特殊炭毡 发布叠层坯体(3#坯本),并探索了预制体结构对C/C复合材料力学性能影响.研究表明:用1#坯体制备的C/C复合材料弯曲强度最高,2#坏体制备的材料弯曲强度最低,随著炭纤维(CF)体积含量的增加,用四种坯体制备的材料弯曲强度增大。确定了弯曲强度的优化配方. 相似文献
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设定两种不同配比强酸氧化剂,以鳞片石墨为原料,采用Hummers法,制备了氧化石墨烯,再经过高温炭化得到热处理氧化石墨烯。并分别以中间相沥青为基体炭前驱体,炭纤维为增强相,氧化石墨烯及其热处理物为热疏导功能体,制备出掺杂氧化石墨烯的炭/炭复合材料。TEM、SEM等表征表明,选用强酸氧化剂组合配比用量较少的制备出的氧化石墨烯,其形貌整体上要优于用量较多的,具有独特的褶皱结构;相比于氧化石墨烯,掺杂其热处理物的复合材料界面覆盖均匀平滑且结合更优良,且其导热系数可达到60 W.m-1.K-1,是无掺杂的纯复合材料两倍多,导热系数得到了较大幅度提高。 相似文献
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《Ceramics International》2022,48(24):36029-36037
Superior performance fillers are considered as an effective means to enhance the performance of carbon/graphite composites. However, poor interfacial properties and incomplete filler networks limit the performance enhancement of the composites. In this study, a new method was proposed to weaken this impact through the synergistic effect of the electrostatic self-assembly of nano carbon black (NCB) onto carbon nanotubes (CNTs). The results showed that the synergistic effect between NCB and the CNTs significantly improved the mechanical and electrical properties of the composites. NCB reduces the porosity of the composites and increases the interaction between the CNTs and matrix. The compressive strength of the composite was 143.2 Mpa, and the flexural strength was 46.3 MPa, which is 210% higher than that of the pristine carbon/graphite composites. Moreover, NCB and CNTs form a globally connected synergistic network in the carbon skeleton. Composites filled with CNTs/NCB exhibited the lowest resistivity and highest thermal conductivity, with a resistance that was 42% lower than that of pristine carbon/graphite composites at 44.8 μΩ m. All of these results suggest that the synergistic effect of CNTs/NCB show great potential to improve the performance of carbon/graphite composites. 相似文献
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以纳米硅、石墨和马铃薯淀粉为原料制备硅-石墨/炭复合负极材料,探讨复合材料的制备工艺对其电化学性能的影响,并采用扫描电镜和X-射线衍射法对材料的颗粒形貌和微晶结构进行表征。研究表明:当复合材料中m(Si)/m(graphite)为1∶4,球磨时间为10 h时,复合材料经20次循环后其可逆容量仍为466 mA·h/g,显示出良好的电化学性能,进一步分析表明纳米硅和石墨均对复合材料的可逆容量做出贡献,而且复合材料中含量较高的石墨的颗粒形貌和微晶结构对其电化学性能起关键性作用。 相似文献
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采用轴棒法4D预制体、煤沥青为前驱体,经过常压、高压相结合的液相浸渍一炭化的致密工艺,制备出高密度轴棒法C/C复合材料。研究了轴棒法C/C复合材料的微观结构及其对轴向室温、高温(2800℃)拉伸破坏形式的影响。结果表明:轴棒法C/C复合材料轴向增强体采用炭棒,出现了一个特殊的界面,即炭棒与基体的“间隙”,主要原因是炭棒内部结合较强和纤维、基体的热膨胀系数不匹配而引起的;间隙的存在,使得轴棒法C/C复合材料的轴向室温、高温拉伸破坏形式出现较大差异,室温拉伸由于界面结合强度弱而引起的炭棒完整的拔出,未起到纤维应有的增强作用;高温拉伸却由于受热膨胀,间隙愈合,界面结合变强,试样从有效部位断裂,纤维增强作用明显提高。 相似文献
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《Journal of the European Ceramic Society》2023,43(10):4363-4373
A rapid and low-cost carbon/carbon (C/C) composites preparation method is proposed: graphite prepreg-coated carbon fiber fabric (CFF) is formed by hot pressing, followed by hot isostatic pressing and high temperature graphitization, to prepare C/C composite with low porosity and high crystallinity. In this method, the carbon fiber (CF) mass fraction can be precisely regulated in the range of 40–95% by the impregnation process conditions of CFF in graphite prepreg. The graphite particles in the preform were graphitized and bonded with CFF by high temperature graphitization. Finally, a ZrO2 anti-ablative layer was applied using sol-gel method. The results show that when the CF mass fraction is 50%, the C/C composite with a crystallinity of 92.21 and a porosity of 3.47% can be obtained, with mass ablation rate of 0.23 mg/s and density of 1.62 g/m3. The method can prepare C/C composites with uniform density and high ablation resistance. 相似文献
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Rong Xue Jiping Wang Yiming Chen Zhejian Zhang Zhichao Xiao Hongyan Xia 《Journal of the American Ceramic Society》2023,106(10):6317-6329
The appropriate carbon content is indispensable for the application of self-lubricating graphite/SiC composites. However, it is a big challenge to retain high carbon content in the reaction-formed graphite/SiC composites because of drastic consumption of carbon by violent reaction with liquid silicon. In this study, a hybrid powder constructed by graphite particles (G) and glassy carbon derived from phenolic resin (PFC) was used as carbon sources, or PFC@G for short, to reserve higher content of carbon in the reaction-formed composites. The weight ratio of phenolic resin to graphite particles was adjusted to obtain an appropriate PFC@G with dense microstructure and close-grained surface. Compared with the graphite/SiC composites only using raw graphite particles as carbon sources, the carbon content of the composites fabricated with compact and large PFC@G has obviously increased (up to 172%). In particular, the carbon content of the composites fabricated with the weight ratio = 0.8 reached a high value of 44.26 vol.%, which exhibited outstanding self-lubrication properties among the four kinds of the composites. The mechanism of reserving higher content of carbon in the graphite/SiC composites by constructing PFC@G is investigated, revealing that a continuous SiC layer formed on the surface of the larger size PFC@G and most closely packed graphite particles inside of PFC@G were insulate from liquid silicon by the layer. 相似文献