Preparation and properties of Cu matrix composite reinforced by carbon nanotubes

Cu matrix composites reinforced by carbon nanotubes(CNTs) were prepared. The effect of carbon nanotubes on mechanical and tribological properties of the Cu matrix composites were investigated. The chemical method for coating CNTs was reported. The morphology of the fracture surfaces and worn surface were examined by SEM.The results show that Cu/coated-CNTs composites have higher hardness, much better wear resistance and antifriction properties than those of the reference Cu alloy (Cu-10Sn) and Cu/uncoated-CNTs composite sintered under the same conditions. The optimal mechanical properties of the composites occurred at 2. 25%(mass fraction) of CNTs. The excellent wear resistance and anti-friction properties are attributed to the fiber strengthening effect of CNTs and the effect of the spherical wear debris containing carbon nanotubes on the tribo-surface.     

碳纤维表面改性对Cf/Mg复合材料微观组织和界面的影响

研究在碳纤维表面分别用化学法镀Ni和溶胶-凝胶法涂SiO2两种涂层,用真空压力浸渗法制备Cf/Mg复合材料.用SEM、EDS和TEM对Cf/Mg复合材料微观组织和界面特征进行分析.结果表明:无涂层的碳纤维与Mg基体浸润性较差,碳纤维在Cf/Mg复合材料微观组织巾分布不均匀,界面结合强度较弱.碳纤维表面包覆Ni或SiO2涂层改善了碳纤维与Mg基体的润湿性;包覆Ni涂层的碳纤维在Mg基体中分布均匀,并在其界面处生成金属间化合物Mg2Ni,界面为强结合;碳纤维表面的SiO2涂层与Mg进行少量的反应生成MgO和Si,界面结合好.能很好地传递载荷.     

SiC纤维表面去碳处理对PIP-SiCf/SiC复合材料力学性能以及界面影响

采用强度测试、SEM、HRTEM等分析测试手段对纤维表面去碳前后SiC纤维强度、复合材料力学性能、纤维表面形貌、复合材料断口形貌以及复合材料界面特征进行分析表征.结果表明,去碳处理后,纤维表面的固有缺陷暴露出来,纤维强度下降约15%,但由其制备的复合材料强度下降只有原纤维制备复合材料的1/6;复合材料断口非常平整,纤维...     

The reinforcing mechanism of carbon fiber in composite adhesive for bonding carbon/carbon composites

A carbon fiber reinforced adhesive was developed for bonding carbon/carbon composites. The Weibull distribution method was used to analyze the bonding strength data, and the results showed that when the volume fraction of carbon fiber was 6 vol.%, the Weibull modulus was 42.9393 and the bonding strength of the adhesive was 11.3763 MPa. A model was proposed to explain the reinforcement of carbon fiber, and it was found that the strength of adhesive was a cubic function of the volume fraction of carbon fiber, and the function model was consistent with the Weibull data. We investigated that the carbon fiber could bridge adhesive matrix as a bridging effect for releasing the residual stress and inhibiting the extension of micro-crack.     

碳纤维表面生长纳米碳管及其增强的炭/炭复合材料

采用化学气相沉积工艺在碳纤维表面生长了纳米碳管,将此种碳纤维作为增强材料,以中间相沥青为基体炭前驱体采用浸渍炭化工艺制备了炭/炭复合材料.观察了所得复合材料断口的微观形貌,测试了抗弯强度及热物理性能.结果表明,碳纤维表面的纳米碳管可以有效地提高纤维与基体的粘结力,复合材料的抗弯性能提高了50%,而对复合材料的导热性能影响较小.     

碳纤维含量对Al2O3+C/ZL109混杂复合材料摩擦磨损性能的影响

利用挤压铸造法制备了A1203 C／ZLl09短纤维混杂金属基复合材料，并探讨了A1203纤维体积分数为12％时，C纤维含量对该混杂复合材料摩擦磨损性能的影响。结果表明：随着C纤维体积分数的增加，复合材料的摩擦因数和磨损率逐渐降低。12％A1203和4％C短纤维的协同作用使复合材料从轻微磨损到急剧磨损的临界转变载荷比基体合金提高了1倍。当载荷低于临界载荷时，复合材料的主要磨损机制为犁沟磨损和层离，C纤维的加入有利于磨损表面裂纹尺寸的减小。但随着载荷的逐渐增加并发生严重磨损时，基体和复合材料的磨损机制均为严重的粘着磨损甚至局部熔化磨损。     

聚醚醚酮骨植入体生物改性研究进展

聚醚醚酮是一种热塑性材料,凭其良好的生物相容性和X射线可透射性,被广泛用于生物医学领域。而PEEK骨植入体与人体骨骼强度存在一定差距,与人体骨组织结合能力较差和抗菌性能等不足,使其在生物领域的应用受到了限制。为了使PEEK更好地应用于人体骨植入领域,获得优异生物性能的PEEK骨植入体已成为研究的重点。概述了PEEK的加工技术、力学性能、骨整合性能和抗菌性能的研究。在此基础上,重点综述了近年来提高PEEK骨植入体力学性能与生物性能的各种改性方法的研究进展。在力学性能方面,对PEEK常用的填充材料碳纤维进行了概述,由于PEEK与碳纤维界面结合强度影响其整体力学性能,重点介绍了提高其结合强度的改性方法。在骨整合性能方面,对钛、二氧化钛和羟基磷灰石涂层材料及喷涂方法进行了概述,以及对等离子喷涂、喷砂、激光蚀刻和浓硫酸刻蚀表面处理方法的优缺点进行了分析。在抗菌性能方面,银离子释放浓度过高时会导致细胞毒性,重点阐述了如何控制银离子释放速度的研究。最后展望了PEEK骨植入体加工和改性的未来发展方向。     

医用碳材料对骨组织的响应及其生物活化改性

对骨种植医用碳材料的种类、碳材料对骨组织间的响应及碳／碳复合材料表面生物活化改性研究现状进行了综述。提出了碳／碳复合材料表面生物活性改性涂层结构，认为碳／碳复合材料表面活性改性的结构应由硬质阻挡层和不降解生物活化层组成；根据目前已研究的生物活性陶瓷种类，提出了碳／碳复合材料表面生物活性涂层具体结构思路，同时展望了医用骨种植碳材料的前景。     

无钯镀镍碳纤维增强Sn-3.0Ag-0.5Cu复合钎料的制备

采用化学镀法在碳纤维表面制备无钯镍镀层,用粉末冶金法制备了以镀镍碳纤维为增强相的Sn-3.0Ag-0.5Cu复合钎料,借助于SEM、EDS、OM等检测手段对其微观组织进行分析,研究镀镍碳纤维含量对复合钎料微观组织和基本性能的影响。结果表明:镀镍碳纤维主要分布在复合钎料的晶界处;随着复合钎料中镀镍碳纤维含量的增加,其弥散度逐渐降低,熔点变化不大;当镀镍碳纤维含量(质量分数)大于1%时,镀镍碳纤维在晶界处的团聚现象严重,复合钎料的电阻率显著升高。添加1%的镀镍碳纤维有助于减小液态复合钎料在助焊剂界面和Cu基板处的表面张力,降低钎料基体的电流密度,使得复合钎料的润湿性提高,电阻率有所降低。     

Structure formation during processing short carbon fiber- reinforced aluminum alloy matrix composites

Nickel- and copper-coated, as well as uncoated, short carbon fibers were dispersed in melts of aluminum or aluminum alloys by stirring followed by solidification of composite melts. Microstructural examina-tion of cast composites indicated extensive damage to the surface of the carbon fibers when uncoated carbon fibers were introduced into the melt under the conditions of the present investigation. When nickel- or copper-coated carbon fibers were used to make composites under similar conditions, the fibers generally did not exhibit observable amounts of fiber surface degradation at the interface, except for small islands of an Al₄C₃ phase. When nickel-coated carbon fibers were used to make composites, the coating reacted with the melt, and NiAl₃ intermetallic phase particles were observed in the matrix away from the fibers, indicating a preference for nucleation of NiAl₃ away from the fiber surfaces. Under a transmission electron microscope (TEM), the NiAl₃ phase was not observed on the surface of carbon fi-bers, except in some regions where the NiAl₃ phase engulfed the carbon fibers during growth. When cop-per-coated carbon fibers were used to make composites, the coating reacted with the melt, and particles of CuAl₂ intermetallic compound were generally dispersed in the matrix away from the fibers, except for a few locations where the CuAl₂ phase was found at the interface under TEM observation. These micro-structures are discussed in terms of nucleation of primary α aluminum and NiAl₃ or CuAl₂ phases and the interaction between short carbon fibers and these phases during growth while the composite was so-lidifying. Additionally, the role of the reaction between nickel or copper coatings and the melt on struc-ture formation is discussed; some of the differences between the nickel and copper coatings are attributed to the fact that nickel dissolves with an exothermic reaction. The differences between solidification of short fiber composites and particle or fiber composite are also discussed.     

Barrier and self‐healing coating with fluoro‐organic compound for zinc

The barrier and self‐healing abilities of a corrosion‐protective coating with a fluoro‐organic compound for zinc was investigated. Several types of fluoro‐organic compounds, having different terminal groups and various numbers of carbon atoms, were coated on a pure zinc plate by dip coating. A fluoro‐organic compound having the terminal group of COF showed excellent barrier resistance, which increased as the number of carbon atoms in the compound increased. The optimal conditions — concentration of fluoro‐organic compound in the solution and the pH of the solution — were determined for coating, based on those that demonstrated more ability than chromate conversion coating. Monitoring the corrosion resistance of a scratched specimen in corrosive solution and observing the surface appearance of the specimen after the corrosion test confirmed the self‐healing ability of the coating with the fluoro‐organic compound. The fluoro‐organic coating had excellent self‐healing ability — equivalent to that of a chromate conversion coating. The self‐healing effect of the coating appeared to be due to the release of the fluoro‐organic compound as a result of the pH increase caused by cathodic reaction in the corrosion process, and the formation of a film on the defect.     

炭纤维增强镁基复合材料的制备

对炭纤维进行了表面化学镀镍处理并通过扫描电镜(SEM)评价了炭纤维化镀层。利用粉末冶金热挤压方法制备了短切炭纤维增强镁合金复合材料并通过超景深金相显微镜观察了纤维在复合材料中的分布。研究了材料中炭纤维含量为0～4%时对复合材料的影响。结果表明,镀镍炭纤维在复合体中均匀分散,炭纤维质量分数为4.0%的镁预制体采用压制压力为420MPa,烧结温度为550℃,保温0.5h后在480℃用280MPa的压力进行热挤压得到的复合材料力学性能较佳。     

Microstructure of carbon fiber preform and distribution of pyrolytic carbon by chemical vapor infiltration

The carbon/carbon composites were made by chemical vapor infiltration(CVI) with needled felt preform. The distribution of the pyrolytic carbon in the carbon fiber preform was studied by polarized light microscope (PLM) and scanning electronic microscope(SEM). The experimental results indicate that the amount of pyrolytic carbon deposited on the surface of chopped carbon fiber is more than that on the surface of long carbon fiber. The reason is the different porosity between the layer of chopped carbon fiber and long carbon fiber. The carbon precursor gas which passes through the part of chopped carbon fibers decomposes and deposits on the surface of chopped carbon fiber. The pyrolytic carbon on the surface of long carbon fibers is produced by the carbon precursor gas diffusing from the chopped fiber and the Z-d fiber. Uniform pore distribution and porosity in preform are necessary for producing C/C composites with high properties.     

Drilling delamination and thermal damage of carbon nanotube/carbon fiber reinforced epoxy composites processed by microwave curing

The drilling-induced delamination and thermal damage of carbon fiber reinforced epoxy composite materials are serious problems especially for high value components of the aviation industry. To suppress the delamination and drilling ablation, an innovative approach was employed in this study. The multiwalled carbon nanotubes (MWCNTs) were introduced to the matrix resin to improve the interlaminar strength and thermal conductivity. The as-prepared composite was processed by microwave curing to enhance the interface strength between carbon fiber and the carbon nanotubes modified matrix. During the drilling processes, optical fiber Bragg grating sensors were utilized to precisely measure the drilling temperature. Experimental results indicated that the interlaminar fracture toughness was increased by more than 66% compared to that of the traditional thermal cured samples without MWCNTs. And the delamination factor was decreased by 16% according to the computerized tomography scanning results. The maximum drilling temperature of the MWCNTs reinforced composite was below the glass transition temperature of the matrix resin and declined by 23 °C compared to traditional composites. With this novel method of carbon nanotube modification and microwave curing, we provide the capability of reducing the drilling delamination and thermal damage of carbon fiber composites simultaneously, and explored the possibility of manufacturing and machining integration.     

Tensile Properties of Polyimide Composites Incorporating Carbon Nanotubes-Grafted and Polyimide-Coated Carbon Fibers

The tensile properties and fracture behavior of polyimide composite bundles incorporating carbon nanotubes-grafted (CNT-grafted) and polyimide-coated (PI-coated) high-tensile-strength polyacrylonitrile (PAN)-based (T1000GB), and high-modulus pitch-based (K13D) carbon fibers were investigated. The CNT were grown on the surface of the carbon fibers by chemical vapor deposition. The pyromellitic dianhydride/4,4′-oxydianiline PI nanolayer coating was deposited on the surface of the carbon fiber by high-temperature vapor deposition polymerization. The results clearly demonstrate that CNT grafting and PI coating were effective for improving the Weibull modulus of T1000GB PAN-based and K13D pitch-based carbon fiber bundle composites. In addition, the average tensile strength of the PI-coated T1000GB carbon fiber bundle composites was also higher than that of the as-received carbon fiber bundle composites, while the average tensile strength of the CNT-grafted T1000GB, K13D, and the PI-coated K13D carbon fiber bundle composites was similar to that of the as-received carbon fiber bundle composites.     

碳界面层制备工艺对SiC_f/SiC材料力学性能的影响

用低压化学气相沉积(LPCVD)法,以丙烯(C_3H_6)为碳源,氮气(N_2)为稀释气制备了2.5维连续碳化硅纤维增韧碳化硅(SiC_f/SiC)复合材料的碳界面层,其厚度为～0.1 mm.研究了不同丙烯含量(体积分数,下同)(60%,50%,45%)对碳层形貌、微观结构及SiC_f/SiC力学性能的影响.结果表明:当C_3H_6含量为60%时,热解碳层表面光滑,石磨化度高;当C_3H_6为50%和45%时,碳层粗糙,有很多较大颗粒存在,石磨化度低.3种复合材料的弯曲强度差别不大,分别为303,311和320 MPa.然而,当C_3H_6含量为60%时,材料韧性断裂,断裂功高;为50%和45%时,材料脆性断裂,断裂功低.不同的纤维拔出滑移阻力是SiC_f/SiC断裂行为不同的原因.     

CeO2在镀镍碳纤维增强铝合金基复合材料中的作用

以稀土氧化物CeO2为添加剂,研究CeO2对镀镍碳纤维增强铝合金基复合材料碳纤维的分布、气孔率以及力学性能的影响,利用扫描电镜分析和拉伸力学性能检测等探讨了CeO2在镀镍碳纤维增强铝合金基复合材料中的行为。结果表明:CeO2能够使碳纤维均匀分布在复合材料中,而不产生分层及团聚;而且能够降低复合材料的气孔率,使轧制态复合材料的抗拉强度、屈服强度分别提高23%和26%。     

载荷下碳纤维复合材料电阻变化研究进展

碳纤维复合材料中具有良好导电性能的碳纤维相互接触形成了导电网络,在外部载荷作用下会发生分层损伤、纤维断裂等损伤或破坏,从而引起导电网络发生变化,改变导电性能,导致电阻发生变化。阐述了国内外在碳纤维复合材料常见导电理论和计算模型相关方面的研究结果,及载荷下碳纤维复合材料电阻变化的研究情况等,指出碳纤维复合材料电阻变化研究存在的不足,并提出了碳纤维复合材料电阻变化研究的趋势。     

TENSILE PROPERTIES OF COATED CARBON FIBER REINFORCED MAGNESIUM COMPOSITES

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Processing and properties of copper-coated carbon fibre reinforced aluminium alloy composites

Aluminium alloy matrix composites with carbon fibre reinforcement were prepared by stir casting method. In order to avoid any interfacial reactions in the carbon fibre reinforced composites, the carbon fibres were coated with copper. The fibres were coated by electroless coating method and then characterized. Composites containing different amounts of carbon fibres were prepared by stir casting and then subjected to age-hardening treatment. Fibre distribution was fairly uniform in the composites containing up to 4 wt% carbon fibres. Tensile strength of the composites was found to be increasing up to 4 wt% carbon fibre.