共查询到20条相似文献,搜索用时 78 毫秒
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超高温本体抗氧化碳/碳复合材料研究 总被引:2,自引:0,他引:2
通过向碳/碳复合材料基体中掺杂难熔金属化合物,研制出了一类集碳/碳材料优异的高温力学、热物理性能和超高温陶瓷材料非烧蚀性能于一体的超高温本体抗氧化碳/碳复合材料。攻克了难熔金属化合物在复合材料中分布以及组元与碳纤维反应控制关键技术,提高了复合材料的力学性能。静态和动态高频等离子风洞超高温本体抗氧化试验表明,在驻点温度达到2 500℃,600 s烧蚀后烧蚀量仅为碳/碳复合材料的1/5,给出了超高温本体抗氧化碳/碳复合材料氧化烧蚀抑制机理。 相似文献
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碳/碳复合材料具有低比重、高比强度、高温下强度保持率高等特点,是各国空天战略急需的国防高技术战略性材料,也是先进航空航天器及其动力系统不可或缺的关键材料,在航空航天及军事领域具有重要应用前景。但制备成本高、性能不稳定、高温易氧化等问题是制约其广泛应用的瓶颈,围绕该类问题开展的研究一直是该领域的热点。 相似文献
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以聚丙烯腈预氧丝整体毡为增强体,采用快速液气相沉积联合沥青浸渍-炭化增密制备高速列车用C/C复合制动材料。研究了所制材料在30℃~800℃时的热扩散率、比热容、导热系数等热物理性能。研究发现:随温度升高,C/C复合材料平行于纤维叠层方向和垂直于纤维叠层方向的热扩散率均呈非线性降低,而比热容呈非线性增大。材料的导热性能表现出明显的各向异性,平行纤维叠层方向的导热系数先升后降,在200℃时出现极大值186.7W.m-.1K-1,是垂直于纤维方向导热系数的5.8倍。而垂直于纤维叠层方向的导热系数表现平稳。通过Wiedmann-Franz比值的分析,认为所制C/C复合材料在低温区以声子导热为主,高温区以电子导热为主。采用本制备工艺可获得导热性能优良的C/C复合材料。 相似文献
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Zhai Y Dou Y Zhao D Fulvio PF Mayes RT Dai S 《Advanced materials (Deerfield Beach, Fla.)》2011,23(42):4828-4850
Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed. 相似文献
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低密度烧蚀防热材料是航天飞行器热防护系统的关键候选材料,其高温力学性能是热防护结构在气动热载荷下结构完整性的关键。本文针对多相纤维增强酚醛树脂低密度烧蚀防热复合材料开展高温压缩性能实验,获得了其压缩强度随温度的变化规律,结合热重、SEM分析了力载荷、热解及氧化反应对压缩强度的影响,揭示了软相碳层弥合和纤维脱黏、拔出两种韧化机制,为多相纤维增强酚醛树脂低密度烧蚀防热复合材料在热防护系统的工程应用提供实验数据支撑。 相似文献
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E. A. Eldridge 《International Journal of Thermophysics》1988,9(2):205-212
The thermal expansion of carbon/carbon material has been measured to 3000 K using a variety of methods. Coupon samples have been measured in a directview dilatometer and an automatic recording dilatometer. Cylindrical or hoop samples, 5 to 50 cm in diameter, have been measured by a fiber-wrap technique. The direct-view or, as it is sometimes referred to, the twintelemicroscope method is generally used when good accuracy is required for measurements to elevated temperatures. The change in length is observed with the use of telemicroscopes aligned on fiducial marks machined on opposite ends of the specimen. An Apple IIe computer controls the automatic recording dilatometer and also provides an output to an X-Y recorder, giving a continuous curve of thermal expansion percentage versus temperature through the range from RT to 300 K. Circumferential thermal expansion is defined as the change in circumference per unit of initial circumference. The change in the circumference of the hoop is measured by wrapping the hoop with a graphite yarn and measuring the change in length with a linear variable differential transformer.Paper presented at the Ninth International Thermal Expansion Symposium, December 8–10, 1986, Pittsburgh, Pennsylvania, U.S.A. 相似文献
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Maoshuai He Alexander I. Chernov Elena D. Obraztsova Jani Sainio Emma Rikkinen Hua Jiang Zhen Zhu Antti Kaskela Albert G. Nasibulin Esko I. Kauppinen Marita Niemelä Outi Krause 《Nano Research》2011,4(4):334-342
Single-walled carbon nanotubes (SWNTs) have been grown on a silica-supported monometallic nickel (Ni) catalyst at temperatures ranging from as low as 450 °C to 800 °C. Different spectroscopic techniques, such as Raman, photoluminescence emission (PLE), and ultra violet-visible-near infrared (UV-vis-NIR) absorption spectroscopy were used to evaluate the diameter and quality of the SWNTs grown over the Ni catalyst at different temperatures. The analysis revealed that high quality SWNTs with a very narrow diameter distribution were obtained at a growth temperature of 500 °C. In the PLE and absorption spectra, differences were observed between the SWNTs grown on Ni and those grown on cobalt (Co). This result expands the potential of growing a specific (n, m) tube species with relatively high abundance by tuning the catalyst composition. Furthermore, the prerequisites for the low temperature growth of SWNTs over a monometallic transition metal catalyst have been elucidated. 相似文献