纳米碳纤维的制备方法及其吸波特性

论述了高温吸波材料--纳米碳纤维的制备方法、吸波性能,并通过比较给出了不同制备方法的特点;讨论了温度、掺杂和表面改性等对纳米碳纤维吸波性能的影响,展望了纳米碳纤维及其复合材料的应用前景.     

空间反射镜新材料研究进展

传统的反射镜材料已满足不了反射镜大口径超轻量化的发展要求。碳纤维复合材料因其出众的性能优势,必将成为未来反射镜材料领域中的重要一员。综述了碳纤维增强SiC复合材料(C/SiC)、碳纤维增强树脂基复合材料(CFRP)、碳纤维增强碳基体复合材料(C/C)这3种具有巨大潜力的反射镜材料,并重点论述了这3种材料的性能特点、应用现状、制备方法及技术瓶颈等问题。最后展望了碳纤维复合材料在反射镜领域的发展前景。     

甲基硅油浸渍对纤维抗氧化性能的影响

采用浸渍工艺在碳纤维和Ｃ／Ｃ复合材料上制备了甲基硅油热解涂层,对涂层中碳纤维和Ｃ／Ｃ复合材料的抗氧化性能进行了研究。结果表明,经浸渍处理后,碳材料的抗氧化性能有一定的提高。另外,由碳纤维编织物经ＣＶＩ方法制备的Ｃ／Ｃ复合材料比碳纤维的抗氧化性增强。     

轨道交通车辆用碳纤维复合材料的性能研究

为了探究轨道交通车辆用的碳纤维复合材料性能,本文制备了一组碳纤维试样和一组玄武岩-碳纤维复合材料试样,通过拉伸试验和压缩试验,分析2组材料的拉伸性能和压缩性能。结果表明,与单一碳纤维组成材料相比,碳纤维复合材料的拉伸性能和压缩性能均更优,更适用于轨道交通车辆,可提升轨道交通安全性。可见碳纤维复合材料能有效改进单一纤维材料,同时还能降低材料成本,具有广阔的应用前景。     

PI-C/Cf的耐热性能和抗磨损性能

采用热解碳(PyC)原位改性碳纤维(CF),制备改性碳纤维增强聚酰亚胺树脂复合材料(PI-C/Cf)。采用热重分析、静态热氧老化等手段表征材料的耐热性能。发现该方法能显著提升复合材料的耐热性能,材料初始分解温度达到了540℃,结合复合材料的高温磨损试验,发现该材料在450℃的磨损率低于1×10~(-6) mm~3/mm,具有较好的高温抗磨损性能,是一种新型的高温抗磨复合材料。在此基础上,结合PI-C/Cf复合材料的微观形貌和元素分布,研究了材料的耐高温、抗磨损机理。     

碳纤维增强酚醛树脂/石墨复合材料双极板的低温热模压试验研究

介绍了国外制备树脂/石墨复合材料双极板的研究结果.研究了低温热模压成型工艺制备酚醛树脂/石墨复合材料双极板,结果表明:酚醛树脂含量为15wt%时,复合材料的导电性能满足双极板的要求,但力学性能偏低.提出了碳纤维增强的解决方案,研究了碳纤维表面处理方法以及碳纤维含量对复合材料导电性能与力学性能的影响.得到对碳纤维进行液相氧化处理,碳纤维含量3wt%是综合性能较好的一种试验方案.采用低温热模压工艺制备低成本酚醛树脂/石墨复合材料双极板,双极板材料的性能突破必将促进燃料电池的商业化发展.     

短碳纤维增强铜基复合材料的摩擦磨损性能研究

采用冷压烧结工艺制备了短碳纤维增强铜基复合材料,考察了该复合材料的干摩擦磨损性能.讨论了短碳纤维含量、载荷、转速等对复合材料摩擦性能的影响.结果表明:复合材料的耐磨性能明显优于基体材料;随着碳纤维含量的增加复合材料的耐磨性能进一步提高;随载荷和转速的提高,摩擦系数和磨损量也随之增加;复合材料由纯铜的粘着磨损转变为剥层磨损,并均伴有一定的氧化磨损.     

碳纤维增强复合材料中改性木质素的应用

目的 解决碳纤维增强环氧树脂复合材料中由双酚A合成的环氧树脂成本高、危害环境与健康、耐化学性差的问题,使木质素代替双酚A合成环氧树脂来制备碳纤维复合材料。方法 通过综述木质素在环氧树脂合成中的改性方法与合成方案的研究进展,分析碳纤维复合材料成型工艺的优缺点。结论 采用不同方法对木质素进行化学改性,可在降低成本的同时提高热稳定性与耐化学性等各项性能。用改性或降解木质素来合成碳纤维复合材料的环氧树脂基体为碳纤维增强材料的研究提供了新的研究方向,对碳纤维增强材料降低成本、提高性能和促进行业发展都具有积极作用。     

气相生长碳纤维增强水泥基复合材料的制备及性能

研究了脱油沥青(De-oiled asphalt)基气相生长碳纤维(VGCFs)增强水泥基复合材料的制备方法及其性能。以脱油沥青作原料,采用化学气相沉积法(CVD)制备出气相生长碳纤维,以此纤维制备水泥基功能复合材料。结果表明:低含量VGCFs的碳纤维增强水泥基复合材料具有良好的抗压强度和导电性能,在VGCFs的掺量由0增至0.6 %范围内,随着VGCFs掺量的增加,碳纤维增强水泥基复合材料的电阻率下降,抗压强度提高。当VGCFs为0.4 %时,VGCFs水泥基复合材料电阻率降低2个数量级,从3.25 ×105 Ω·cm 降为1.49 ×103 Ω· cm ,抗压强度提高28.8 %,为最佳掺量。      

3D编织碳纤维复合材料的制备及其屏蔽性能的研究

用三维五向3D编织技术和模压成型工艺制备了碳纤维增强环氧树脂基电磁屏蔽复合材料,测试结果表明,三维五向编织结构可形成良好的导电网络,基于该结构制成的碳纤维复合材料屏蔽效能最高可达85dB,编织体整体化学镀镍可使材料的屏蔽效能提高约15dB,镀镍后的复合材料在14kHz～18GHz频段内具有较高的屏蔽效能,最高可达95dB。同时发现,该材料的屏蔽性能显示各向异性,这与编织体的纤维取向和电磁波的极化方向有关。     

碳纤维增强铜基复合材料研究进展

本文综述了碳纤维在铜基复合材料中的作用及其表面处理技术的发展现状。总结了近年来碳纤维表面改性方法以及存在的主要问题,分析了碳纤维对铜基复合材料组织的形成及其性能的影响。最后展望了碳纤维的发展前景。     

碳纤维含量对短碳纤维－铜复合材料性能的影响

用粉末冶金法制造了碳纤维分布均匀的碳纤维一铜复合材料，测定了复合材料的力学性能和物理性能，表明在碳纤维与铜基体之间存在界面结合，碳纤维含量对复合材料性能影响极大。     

碳纤维含量对短碳纤维-铜复合材料性能的影响

用粉末冶金法制造了碳纤维分布均匀的碳纤维一铜复合材料,测定了复合材料的力学性能和物理性能,表明在碳纤维与铜基体之间存在界面结合,碳纤维含量对复合材料性能影响极大。     

碳纤维增强铜基复合材料的性能研究

采用粉末冶金法制备了短碳纤维增强铜基复合材料。经对不同碳纤维含量试样的硬度及导电性能的测定，并在干摩擦的条件下研究了碳纤维增强铜基复合材料的摩擦磨损性能，同时对磨损表面的微观结构进行观察来分析其磨损机理。实验结果表明，随着碳纤维含量的增加，该材料的硬度和耐磨性均有所增加，但其导电性有所下降。     

短碳纤维-铜复合材料的研制

研究了用粉未冶金方法制造短碳纤维-铜复合材料,对这种复合材料的力学性能及物理性能进行了测试,证明该复合材料中,碳纤维与铜基体间存在着界面结合。     

Formicary-like carbon nanotube/copper hybrid nanostructures for carbon fiber-reinforced composites by electrophoretic deposition

An electrophoretic deposition process has been applied to produce unique carbon nanotube (CNT)/copper nanostructures on the carbon fiber surfaces. During the deposition process, ionized copper and positively charged CNTs are accelerated towards the carbon fiber under applied electric fields. An interconnected formicary-like network of nanotubes and nanoparticles is formed where copper nucleation and growth occurs predominantly at nanotube crossing and edge-contact locations. When embedded in a structural composite the CNT/copper structures create a highly conductive and strongly bonded network shown by significant enhancements in both electrical conductivity and interlaminar shear strength as compared to composites without the CNT/copper nanostructures.     

Experimental description of thermomechanical properties of carbon fiber-reinforced TiC matrix composites

Titanium carbide ceramic is a good potential material used in high temperature environment for its good strength, erosion resistance and thermal stability. Unfortunately, the low thermal shock resistance and low fracture toughness are the well-known impediments to its application as high temperature structure components. In order to extend the application of TiC ceramics at high temperature, 20 vol.% short carbon fiber was added into TiC matrix to improve the thermomechanical properties. With the incorporation of carbon fiber, the thermal expansion coefficient of TiC composites was decreased and the thermal conductivity was increased slightly below 900 °C. The flexural strength was improved from 471 MPa for monolithic TiC to 593 MPa for TiC composites, and the strengthening effect of carbon fiber became more prominent at high temperatures. The addition of fiber decreased the elastic modulus of TiC composite. The elastic modulus of the composite decreased with increasing temperature. The improvement of high temperature strength and thermal conductivity and the decrease of thermal expansion will benefit the application of TiC composites in high temperature environment where the temperature usually varies.     

Mechanical properties and corrosion behavior of lead-silicon carbide fiber and lead-carbon fiber composites made by electrodeposition

Multifilament silicon carbide fibers (Nippon Carbon, Nicalon type) and carbon fibers (Thornel, Pan T 300 and Pitch type) were used to produce lead-matrix composite materials for battery plate grid applications. Lead was impregnated into the fibers by electrodeposition from fluoborate baths. The electrical conductivity of carbon fibers was sufficient for direct electroplating; silicon carbide fibers were electroless plated with copper beforehand. The experimental conditions for good penetration of lead into the fiber tows were determined.Unidirectional composite samples with a fiber volume fraction of 5 to 25% were prepared from both lead impregnated fiber sheets and rods by hot-pressing (280°C, 50 MPa, 5–30 mm). The flexural strength and modulus of these samples were measured as a function of the infiltration current density and of the fiber volume fraction. Ultimate strengths in the range 300–400 MPa were attained for both lead-silicon carbide and lead-carbon composites, at a fiber volume fraction of about 25%. These latter composites exhibited a good corrosion resistance towards 38.5 wt-% sulfuric acid under non-anodic conditions.     

Influence of the interface structure on the thermo-mechanical properties of Cu–X (X = Cr or B)/carbon fiber composites

This study focuses on the fabrication, for power electronics applications, of adaptive heat sink material using copper alloys/carbon fibers (CF) composites. In order to obtain composite material with good thermal conductivity and a coefficient of thermal expansion close to the ceramic substrate, it is necessary to have a strong matrix/reinforcement bond. Since there is no reaction between copper and carbon, a carbide element (chromium or boron) is added to the copper matrix to create a strong chemical bond. Composite materials (Cu–B/CF and Cu–Cr/CF) have been produced by a powder metallurgy process followed by an annealing treatment in order to create the carbide at the interphase. Chemical (Electron Probe Micro-Analysis, Auger Electron Spectroscopy) and microstructural (Scanning and Transmission Electron Microscopies) techniques were used to study the location of the alloying element and the carbide formation before and after diffusion. Finally, the thermo-mechanical properties have been measured and a promising composite material with a coefficient of thermal expansion 25% lower than a classic copper/carbon heat sink has been obtained.     

碳纤维随机填充橡胶复合材料导热性能的数值模拟

运用随机顺序添加算法RSA(Random sequential addition method),基于均匀化理论建立了碳纤维填充橡胶复合材料代表体积单元RVE(Representative volume element)模型,利用有限元方法数值模拟研究了碳纤维对橡胶复合材料导热性能的影响。结果表明:在相同的填充分数下,碳纤维根数对复合材料导热性能的影响较小;合理安排碳纤维空间分布及纤维取向能有效提高复合材料的导热性能;复合材料的导热性随着碳纤维填料含量及长径比的增加而增大;与理论模型相比,基于碳纤维填料随机分布模型所得模拟结果与实验值较接近,尤其在高填充分数时与实验值吻合较好,可以更好地预测纤维填料填充复合材料的导热性能,对制备具有高填充分数的高导热复合材料具有一定的指导意义。