铜基石墨复合材料的研究进展

铜基石墨复合材料是一种广泛应用于摩擦材料和电接触材料等领域的金属基复合材料.综述了铜基石墨复合材料在改善铜基体与石墨增强体结合方面的研究进展,主要包括基体合金化、石墨的表面处理、添加粘结剂等,重点介绍了铜基石墨复合材料的制备工艺方法,并概述了其导电导热性能、摩擦磨损性能、工艺性能及应用,最后展望了铜基石墨复合材料的研究重点和发展方向,认为取代现有的易切削铅黄铜合金将成为铜基石墨复合材料今后研究和应用的一个亮点.     

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.     

不同陶瓷颗粒增强Cu基复合材料的制备及导电性能

以纯铜为基体,以WC、AlN、TiN、MgB2等具有不同导电性能与密度的陶瓷颗粒为增强相,采用球磨-冷压-烧结工艺制备了WCp/Cu、AlNp/Cu、TiNp/Cu和MgB2p/Cu系列复合材料.研究了制备工艺的不同环节对铜基复合材料导电性能的影响,讨论了不同陶瓷颗粒增强铜基复合材料的导电性能.结果表明相同制备工艺及体积分数条件下,以具有不同导电性能与密度的陶瓷颗粒作为增强相的铜基复合材料的导电性能相近,球磨、冷压、烧结、复压及复烧等工艺环节对铜基复合材料导电性能有不同程度的影响,提高铜基复合材料的致密度为提高其导电性能的关键.     

碳纤维(短纤)增强Cu基复合材料的研究

碳纤维增强 Cu 基复合材料以其优良的导电、导热、减摩擦、抗磨损性能而受到重视~([1])。我们研究了用非连续碳纤维增强 Cu 基复合材料的制造工艺及性能。针对碳纤维与 Cu 化学相容性好,但润湿性差~([2]),两者直接复合、界面结合很弱的     

颗粒种类及制备工艺对铜基材料性能影响

以纯铜为基体,以WC、AlN、TiN、MgB2等具有不同导电性能与密度的陶瓷颗粒为增强相,采用粉末冶金工艺制备了WCp/Cu、AlNp/Cu、TiNp/Cu和MgB2p/Cu系列复合材料.研究了不同增强颗粒、制备工艺的不同环节对铜基复合材料导电性能的影响.结果表明:相同制备工艺及体积分数条件下,以具有不同导电性能与密度的陶瓷颗粒作为增强相的铜基复合材料的导电性能相近,混粉、压制、烧结、复压及复烧等工艺环节对铜基复合材料导电性能有不同程度的影响,提高铜基复合材料的致密度为提高其导电性能的关键.     

石墨烯/铜复合材料的制备及其性能与应用

石墨烯具有特殊的二维平面蜂窝状结构和优异的性能,是理想的金属复合材料的增强体。粉末冶金法作为制备石墨烯/铜复合材料的传统的方法,面临着石墨烯难以分散以及与金属基底结合差等困境,尽管该法可有效提高复合材料力学性能,但也降低了其导热导电性能。随着人们对石墨烯/铜的结构与界面问题的深入研究,一些新的粉体制备工艺如原位生长法制备出了优异性能铜基复合材料,这将有助于开发出优异性能的铜基电接触材料。从石墨烯/铜复合材料的制备工艺(化学气相沉积法、机械混合以及原位生长石墨烯等)、性能(机械性能、导热性能以及抗氧化和防腐蚀性能等)及其在电接触材料的应用和石墨烯/铜的未来发展趋势等方面进行阐述。     

石墨烯/铜复合材料的制备及其性能与应用

石墨烯具有特殊的二维平面蜂窝状结构和优异的性能,是理想的金属复合材料的增强体。粉末冶金法作为制备石墨烯/铜复合材料的传统的方法,面临着石墨烯难以分散以及与金属基底结合差等困境,尽管该法可有效提高复合材料力学性能,但也降低了其导热导电性能。随着人们对石墨烯/铜的结构与界面问题的深入研究,一些新的粉体制备工艺如原位生长法制备出了优异性能铜基复合材料,这将有助于开发出优异性能的铜基电接触材料。从石墨烯/铜复合材料的制备工艺(化学气相沉积法、机械混合以及原位生长石墨烯等)、性能(机械性能、导热性能以及抗氧化和防腐蚀性能等)及其在电接触材料的应用和石墨烯/铜的未来发展趋势等方面进行阐述。     

铜基复合材料的摩擦磨损性能研究现状

铜基复合材料具有优异的性能及广泛的应用,而随着其应用的愈加广泛,对其摩擦磨损性能的要求也愈加严格。综述了国内外颗粒增强、石墨自润滑、纤维增强和碳纳米管增强铜基复合材料的摩擦磨损性能,并简述了目前铜基复合材料存在的一些问题及展望。     

碳纳米管增强铜基复合材料的研究进展

本文针对碳纳米管增强铜基复合材料研究中的关键问题进行了综述。对碳纳米管增强铜基复合材料的制备技术进行了分类,总结了粉末冶金法、电化学法以及其他方法的研究进展,并强调了制备方法和复合材料性能之间的关系。分析了碳纳米管增强铜基复合材料的界面特征,并概述和总结了其力学性能、电学性能、热学性能、摩擦磨损性能等方面的研究进展和存在问题。指出改善复合材料的制备方法,获得分散均匀的碳纳米管且与铜基体结合良好的复合材料是提高其综合性能的关键。     

镁合金高速冲击载荷下的变形行为研究进展

概述了国内外对镁合金在高应变率加载条件下的力学行为及其高速变形时组织中绝热剪切带形成机制的研究现状,归纳了在镁合金动态力学行为及微观变形机制方面以及镁合金中形成绝热剪切带带内组织成因研究方面存在的不足。基于此,提出了镁合金动态力学行为及其在动态变形过程中微观组织演变机制的研究重点,并指出了进一步尚需开展的工作。     

关于金属纳米材料力学性能的几个问题

金属纳米材料具有独特的力争陛能,如高强度、超高延展性和理想弹塑性等。本文通过对几种纳米金属材料的力学性能的阐述,讨论了它们的强度、应变硬化、超塑性、理想弹塑性等相关的力学性能。并简要地指出了影响其力学性质的主要因素。     

Improvement of Creep and High Temperature Tensile Properties by Adding W to Orthorhombic Ti2AlNb-Based Alloys

The Orthorhombic Ti2AlNb-based alloys (O alloys) are potential high temperature materials for applications in aircraft engines for their high specific strength. In this paper, with the purpose of enhancing the mechanical properties, W is added to O alloys as the quarternary alloying element. The effects of W additive on the high temperature tensile properties and creep resistance are investigated. The effects of boron doping on these properties are also studied.     

油气井射孔器用炸药及其安全性

介绍了中国和美国射孔器所用的单质和混合炸药43种.根据耐热性,射孔器可分为普通型、高温型和超高温型三类.射孔器和炸药的耐热性与其受热时间有关,最后文中叙述了射孔器的安全性能.     

Aluminum oxynitride dielectrics for multilayer capacitors with higher energy density and wide temperature properties

Amorphous aluminum oxynitride (AlON) possesses unique properties of high dielectric strength, high resistivity, low loss, high decomposition temperature, chemical inertness, and high thermal conductivity. These properties make it a candidate for a next generation capacitor dielectric. DC pulsed magnetron reactive sputtering is used to produce amorphous AlON films on various substrates. Dielectric properties are optimized by adjusting DC power, pulse frequency, total pressure, substrate temperature, and gas ratio. Simple parallel plate structures are utilized to characterize the dielectric properties. Clearable electrodes are evaluated in device performance. Defects cleared without significant loss of capacitance. Temperature dependent dielectric properties were evaluated from − 200 °C to + 400 °C. Stacked multilayer capacitor device is developed for high energy density and wide temperature applications.     

Evaluation of the consistency of fiber reinforced cementitious composites

The rheological properties of fresh concrete, mortar or cement paste are among the most important parameters when cementitious building materials are placed. New material designs, like high or ultrahigh performance concretes, include the addition of a high volume of fibers to the fresh mix influencing its workability properties. However, the analysis of the rheological properties of fiber reinforced cementitious composites is difficult. Conventional methods mostly do not apply, especially when a high fiber content and relatively stiff mixtures are used. For this reason, a new method was developed to evaluate the workability of fiber reinforced composites. This method was applied to carbon and PVA fiber reinforced high performance composites and was used to optimize the rheological properties of these composites for an application in a centrifugation casting process.     

高速搅拌对淀粉／聚乙烯醇共混物薄膜性能的影响

通过高速搅拌，将淀粉与聚乙烯醇进行溶液共混，制备了淀粉／ＰＶＡ共混薄膜。测定了高速搅拌前后共混薄膜的力学性能。透明性，耐水性及生物降解性。结果表明，高速搅拌改善了淀粉／ＰＶＡ薄膜的力学性能，透明性与耐水性，并可提高共混膜的全用稳定性。     

Determination of moisture effects on impact properties of composite materials

Many applications of structural materials involving composites include impact or dynamic loading in a humid environment. Composite materials are known to degrade when subjected to humid conditions, and therefore the humidity confounds the difficulty of determining the high strain rate behavior of composites. Several researchers have found that water absorption by composites causes degradation of matrix dominated quasi-static properties. However, very little is known of the effect of absorbed moisture on the high strain rate properties of polymer matrix composites, that are useful in the automotive, aerospace, and naval applications of composite structures. A Split-Hopkinson Pressure Bar facility is used herein to study the effect of absorbed moisture in high strain rate tests (200–1200/s) of a unidirectional IM7/8551-7 graphite/epoxy composite. The study includes dry, medium, and saturated moisture conditions. The tests show significant variation of high strain rate properties from static properties, and the reasons are identified. In addition, a better understanding of the effect of the matrix and fiber/matrix interface on the high strain rate properties of composites is achieved.     

高渗透孔隙水压对混凝土力学性能的影响试验研究

模拟高坝混凝土工作环境,将混凝土标准试件浸没于高压水体中,在混凝土内造成高渗透孔隙水压,研究高孔隙水压作用后混凝土产生的强度、弹性模量,含水量和声速等宏观指标的变化。试验中具体开展了混凝土试块外不同水压（孔隙水压）、不同时间、不同混凝土等级、不同最大骨料粒径4个因素的影响研究。试验采用正交试验设计法进行设计,关于高渗透...     

The mechanical properties of high stiffness hot-compacted polypropylene: a new development

Recent research on the mechanical properties of hot-compacted polypropylene composites is reported. It is shown that incorporation of new high performance polypropylene tapes leads to significant improvements in tensile and flexural properties. The high temperature properties of these new composites are outstanding, showing higher stiffness and very low creep under permanent load. Comparisons are presented with both chopped glass-reinforced and continuous glass-reinforced polypropylene composites.