Carbon–Carbon Composite Materials

Data are summarized on the performance characteristics and properties of Russian-produced and foreign carbon–carbon composite materials for various engineering applications. The effect of neutron irradiation on their macroscopic properties and structure is examined. The relationships between the radiation-induced dimensional changes and properties of the composites are established, which can be used in assessing the engineering performance and optimizing the fabrication of carbon–carbon composites.     

碳/碳复合材料基体用中间相沥青

中间相沥青具有高残碳率、高密度、低的密度变化及易石墨化等优点 ,是较理想的碳 /碳 (C/C)复合材料基体前驱体。本文从 C/ C复合材料制备工艺的角度 ,阐述了制备 C/ C复合材料用的中间相沥青的主要特性 ,其中包括中间相沥青的流动性、在碳化过程中的稳定化、微观结构以及中间相沥青基 C/ C复合材料的界面结构。     

纳米碳管增强炭/炭复合材料的研究进展

纳米碳管(CNTs)具有独特的结构、优异的力学性能、热稳定性与传导性能,是炭/炭(C/C)复合材料理想的增强体.综述了纳米碳管增强炭/炭(CNTs/C/C)复合材料的制备方法,讨论了该复合材料的微观结构、摩擦学性能和传导性能,并展望了CNTs/C/C复合材料的潜在应用和发展趋势.     

粉末涂层碳纤维制备碳/碳复合材料研究进展

综述了国内外碳/碳复合材料的主要用途和制备方法,通过比较发现粉末预涂层制备碳/碳复合材料是一种低成本、短制备周期的理想方法,它包括基体树脂和碳纤维的选择、碳纤维的表面处理及碳纤维丝束的铺展.采取层压成型制备试样,经高温炭化和石墨化制备碳/碳复合材料.     

炭/炭复合材料表面预炭层的制备及其性能研究

为在炭/炭复合材料表面制备C/SiC浓度梯度高温抗氧化涂层,预先用料浆涂刷-高温处理工艺在其表面制备了预炭层.借助XRD、Raman和SEM等测试手段对所制备预炭层的组织结构和微观形貌进行了表征,讨论了不同的原料配比和炭化温度对预炭层结构的影响,并对预炭层与基体的结合性能进行了测定.研究结果表明：制备的预炭层结构致密,与基体具有较好的结合性能,其结合强度可达10.95MPa.不同的原料配比和炭化温度影响了炭层序态结构的形成,最终形成了不同结构的预炭层.     

Increasing the Tensile Property of Unidirectional Carbon/Carbon Composites by Grafting Carbon Nanotubes onto Carbon Fibers by Electrophoretic Deposition

Although in-situ growing carbon nanotubes(CNTs) on carbon fibers could greatly increase the matrix-dominated mechanical properties of carbon/carbon composites(C/Cs),it always decreased the tensile strength of carbon fibers.In this work,CNTs were introduced into unidirectional carbon fiber(CF) preforms by electrophoretic deposition(EPD) and they were used to reinforce C/Cs.Effects of the content of CNTs introduced by EPD on tensile property of unidirectional C/Cs were investigated.Results demonstrated that EPD could be used as a simple and efficient method to fabricate carbon nanotube reinforced C/Cs(CNT—C/Cs) with excellent tensile strength,which pays a meaningful way to maximize the global performance of CNT—C/Cs.     

Carbon/Carbon Composite Friction Discs for Aerospace

Carbon/carbon friction discs are produced at Newmet Composites (a division of New Metals & Chemicals Ltd.) for flap jam systems in airplanes. They offer excellent mechanical and friction properties. New carbon/carbon composite grades have been developed at Newmet Composites during the last few years. Another material that is used for this applications is bronze. Different material grades and different designs are compared in this paper. The key‐properties discussed are compression strength, flexural strength and friction behaviour. The friction tests were simulating the friction behavior during the application of such discs. Compression tests were made to define the possible application: For the application in the flap jam system the compression strength has to be 207 MPa at the minimum, for other applications this is not necessarily required. A test described briefly in this paper was developed for flexural strength. The flexural strength is not very important during the application, but important when the discs are being handled and built in. It could be shown that both production parameters and design have a significant influence on the performance of carbon/carbon friction discs. These results are needed to define further applications for these materials. Finally the material carbon/carbon is briefly compared with alternative materials.     

Effect of Growth Temperature on Carbon Nanotube Grafting Morphology and Mechanical Behavior of Carbon Fibers and Carbon/Carbon Composites

High-purity carbon nanotubes(CNTs) with different orientation and lengths were grafted on carbon fibers(CFs) in woven fabrics by using double injection chemical vapor deposition and adjusting the growth temperature.Scanning electron microscopy(SEM),transmission electron microscopy(TEM) and Raman investigations reveal that the grafted CNTs change from being predominantly aligned and uniform in diameter to absolutely disordered and variable in diameter,whilst they show significantly increased crystallinity,as the growth temperature is increased from 730 °C to 870 °C.In tensile tests of fiber bundles,much more strength degradation of CFs was observed after the growth process at higher temperature than that at lower temperature.These hybrid preforms produced at different growth temperatures were used to reinforce carbon/carbon(C/C) composites.An increment of 34.4% in out-of-plane compressive strength(OCS) was obtained for the composites containing CNTs grown at 730 °C,while the OCS increment exhibits an obvious decrease with increasing the growth temperature.Compared with the higher growth temperature,the lower temperature contributes to the decrease in the strength loss of reinforcing fibers and meanwhile the growth of large extending length of CNTs,which can provide long reinforcement to the pyrocarbon matrix,and thus increase the compressive strength better.     

碳纳米管

概述了碳纳米材料的发展及它们的性能和应用,同时介绍了一些比较成熟的制备纳米材料的技术。在此基础上分析了碳纳米管的形成过程和碳纳米管的微观结构,以及碳纳米管制备工艺对微观结构的影响。     

碳／碳复合材料的氧化与防护

碳/碳复合材料的氧化敏感性限制了它的应用,为满足未来宇航飞行器等对高温结构材料的需要,必须彻底解决碳/碳复合材料的氧化防护问题。本文在认真分析碳/碳复合材料氧化过程的基础上,全面总结了提高碳/碳复合材料的抗氧化途径,其具体方法包括:材料内部结构、纤维、基体的改进和用各种方法在其表面施加保护涂层。同时,进一步发现:一种包括硼酸盐玻璃作内涂层,以SiC、Si_3N_4、SiO_2等作为外涂层的多层涂层系统,能在1700℃以下对碳/碳复合材料提供较好的防护。     

Carbon/Carbon – an inverse composite structure

Carbon/carbon composites are a type of material, which combines the refractory properties of carbon with the high strength and stiffness of carbon fibres. Although one could not expect a reinforcement by the combination of a carbon matrix with carbon fibres the fibre properties can be used. Additionally the material shows a pseudoplastic fracture behaviour in spite of its ceramic nature. Explanations for this inverse behaviour in comparison to other composite structures will be presented including mechanical viewpoints, interactions at the interface between fibre and matrix, their influence to the fracture characteristics and micromechanical behaviour as well as the interactions between modulus and microstructure. Furtheron examples for some industrial applications are described.     

Carbon microflowers

Micro- or nanoflowers are self-organized, planar or 3D microstructures similar to macroscopic flowers. The interest in microflowers has increased in recent years because of many potential applications of microflowers, due to their high specific surface area. The analysis of the morphology of carbon flower-like microstructures produced in low-current plasma, generated by high voltage electrical discharge in a mixture of cyclohexane with argon as the carrier gas has been presented in the paper. It was shown that various carbon microstructures, including microfibers and microflowers of different pattern, can be synthesized on the electrodes by the same plasma method, at various process parameters.     

炭膜

炭膜是由炭构成的膜状物质,也可以说,具有不同杂化轨道形成的碳所组成的膜体.按其制法、结构、性能和用途分类,它又可细分为热解炭膜、四配位非晶炭膜、纳米管炭膜、玻璃状炭膜、无定形炭膜、高结晶度石墨炭膜;机械用炭膜、分离用炭膜、工具领域用金刚石炭膜、为消除静电堆积用晶须炭膜等.