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。     

非连续增强铜基复合材料的研究现状

非连续增强铜基复合材料具有很高的导电、导热性能,以及优异的摩擦磨损特性和较高的高温力学性能,是导电、导热、耐磨、减摩等领域的理想材料。本文综述了非连续增强铜基复合材料的研究现状,介绍了该类材料的设计原理以及力学、摩擦磨损、导电导热等性能,回顾了材料的制备工艺,指出了各种工艺的优缺点,最后阐述了非连续增强铜基复合材料的发展方向。     

铜基复合材料的研究新进展

主要从增强体材料、增强机理、制备方法等方面简述了铜基复合材料的研究进展情况,总结了铜基复合材料的增强体材料的选用原则、种类和特点,并根据增强体材料的形态重点阐述了4种增强机理,介绍了7种制备铜基复合材料方法的工艺机理、特点,最后指出了铜基复合材料的应用领域,并展望了该类材料的发展方向.     

影响炭/炭复合材料摩擦学性能的因素分析:材料的性质

影响炭/炭复合材料摩擦性能的因素很多,综述了国内外的研究现状,评价了材料的性质对炭/炭复合材料摩擦磨损性能的影响,阐述了模量、石墨化度、密度、预制体的类型、基体类型、热解炭结构等因素.     

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。     

熔融渗硅法制备C/C-SiC复合材料的研究进展

综述了熔融渗硅法制备C/C-SiC复合材料的国内外研究和应用现状,重点分析了碳纤维预制体和C/C多孔体的制备,以及熔融渗硅过程对C/C-SiC复合材料性能和结构的影响,介绍了C/C-SiC复合材料作为热结构和摩擦材料在航空航天和先进摩擦制动系统中的应用,提出了C/C-SiC复合材料制备过程中存在的问题和今后研究的重点.     

注射成形Cu-Fe-C摩擦材料的性能

采用注射成形工艺制备了Cu-Fe-C坯料,通过溶剂脱脂和热脱脂、烧结制备出Cu-Fe-C摩擦材料。研究了Cu-Fe-C摩擦材料的力学性能及摩擦磨损性能,重点分析了Fe含量对Cu-Fe-C摩擦材料性能的影响。实验结果表明:材料中铜颗粒之间存在的孔隙及石墨为主要的裂纹源和扩展途径,使材料发生脆性断裂;高硬度、耐磨的Fe颗粒分布于铜基体中,可以提高材料的硬度、强度;当Fe含量达到8%时,材料的硬度为58HV,抗拉强度为148MPa;当摩擦速度为100～400r/min时,Fe颗粒的加入提高了材料磨损量、摩擦系数,降低了材料的磨损性能;高速摩擦条件下,Fe的加入促进摩擦表面氧化膜的形成,提高了材料的耐磨性能。     

影响炭／炭复合材料摩擦学性能的因素分析：材料的性质

影响炭／炭复合材料摩擦性能的因素很多，综述了国内外的研究现状，评价了材料的譬质对炭／炭复合材料摩擦磨损性能的影响，阐述了模量、石墨化度、密度、预制体的类型、基体类型、热解炭结构等因素。     

镀铜石墨/铜复合材料的组织和摩擦磨损性能

本实验以电解铜粉为基体,镀铜石墨为润滑相,采用放电等离子烧结技术(SPS)制备镀铜石墨/铜复合材料,研究了镀铜石墨含量对复合材料微观组织、硬度、孔隙率和摩擦磨损性能的影响。结果表明:镀铜石墨均匀分散在Cu基体中能细化晶粒、均匀组织,石墨表面镀铜层能够增强石墨与Cu基体的界面结合。当镀铜石墨含量超过4wt%,复合材料的硬度和孔隙率变化幅度明显增大。镀铜石墨具有细晶强化作用,能提升复合材料的硬度,其含量为4wt%时,复合材料的硬度达到最大值57.8HV,但镀铜石墨含量和孔隙率的共同作用使得复合材料的硬度呈先增大后减小的趋势。随着镀铜石墨含量增加,复合材料孔隙率逐渐增大,摩擦系数、磨损量逐渐减少,镀铜石墨含量为8wt%时,复合材料的摩擦系数、磨损量相比纯铜分别降低63.9%、96.3%。镀铜石墨作为润滑相紧密镶嵌在铜基体中,显著提高了复合材料的摩擦磨损性能。复合材料摩擦磨损机理主要为磨粒磨损、粘着磨损和氧化磨损。     

颗粒增强铜基复合材料的研究进展

为了研究颗粒增强相对铜基复合材料的性能的影响,对不同类型铜基复合材料的特点及其制备方法进行对比分析,探讨了颗粒相的生成机制,重点论述了颗粒增强相的类型及铜基复合材料的制备工艺.结果表明在铜基体中引入纳米分散相进行复合,可以使铜合金的力学性能得到极大改善,其中机械合金化和原位复合化学反应获得的纳米陶瓷颗粒在铜基复合材料中效果最佳;反应喷射沉积成型法、液相反应原位生成法和机械合金化法在制备纳米粒子增强铜基复合材料方面有着良好的应用前景.     

Controlled Friction Behaviors of Porous Copper/Graphite Storing Ionic Liquid through Electrical Stimulation

Porous copper/graphite composites storing stimuli‐responsive lubricant can be used to fabricate a new kind of electrical contact friction materials. However, the synergetic lubricating effect of solid and liquid lubricants incorporated into the copper matrix is rarely discussed. In this work, neat copper and its composites storing ionic liquids (ILs) have been successfully prepared via a template‐free strategy. The effect of frictional, electrical, and electro‐frictional coupling stimulation on the tribological behavior of the copper filled with graphite has been investigated using ball‐on‐disk friction tests. Results show that a high voltage may accelerate the release of the ILs stored in the composite to the friction interface, thereby resulting in a low coefficient of friction (COF) (ca. 0.14) at the voltage of 0.5 V, which is superior to those of the pure copper without applying voltage. The COF is more stable in copper/graphite composite storing ILs (SI) than in copper‐SI. Therefore, the graphite efficiently protects the surface of the sample from wear and electrochemical corrosion.

     

热压烧结制备SiC增强石墨复合材料及其性能

以天然鳞片石墨为起始原料,SiC颗粒为增强相,采用热压烧结工艺制备了SiC增强石墨复合材料。研究了SiC含量对SiC增强石墨复合材料微观结构、力学性能和摩擦性能的影响。结果表明:SiC颗粒均匀分布在石墨基体中,降低了基体中的孔隙率;随着SiC含量增加,SiC增强石墨复合材料的相对密度和弯曲强度相应增加,开孔率显著降低,当SiC含量达到40vol%时,SiC增强石墨复合材料中形成了SiC网络骨架结构,相对密度达到了94.2%,比商品高强纯石墨材料提高了11.8%,弯曲强度达到了146 MPa,比商品高强纯石墨材料提高了147%;基体石墨保持了层状结构;SiC含量低于40vol%时,SiC增强石墨复合材料的摩擦系数随SiC含量的增加轻微增加,与纯石墨材料的摩擦系数相当,具有良好的摩擦性能。     

石墨含量对铜-石墨-乳化沥青复合材料组织和性能的影响

以电解铜粉与石墨粉为原料,阴离子乳化沥青为粘结剂,采用粉末冶金技术制备了铜-石墨-乳化沥青复合材料,并通过XRD、EDS和SEM对石墨含量为2wt%~8wt%的铜-石墨-乳化沥青复合材料微观组织进行表征,研究了铜-石墨-乳化沥青复合材料的摩擦磨损性能、力学和电学性能,并与不含乳化沥青的铜-石墨复合材料进行比较。结果表明,乳化沥青可以有效防止石墨颗粒的聚集,对石墨和铜基体起粘结作用;在两相界面处几乎没有间隙,并且产生了层片状石墨;石墨含量为4wt%的试样磨损量最小,仅为0.0049 g,摩擦系数约为0.025;增加载荷和石墨含量会增大磨损量,但会降低摩擦系数;在滑动摩擦期间,磨损表面会出现裂纹、犁沟、凹陷、小颗粒和层片状结构,但其程度要比不含乳化沥青的复合材料低。      

电铸制备铜-石墨复合材料的研究

在酸性硫酸铜溶液中采用电铸技术制备了铜-石墨复合材料.表面活性剂、微粒浓度、电流密度和搅拌速度等工艺条件对微粒含量具有不同的影响.非离子表面活性剂对微粒共沉积具有较好的效果;随着微粒浓度增大,微粒含量也逐渐增大,最后趋于稳定值;电流密度增大使微粒含量降低;搅拌速度增大时微粒含量存在最大值.铜-石墨复合材料的硬度和摩擦系数随着微粒含量增大而减小,但是磨损量先是减小而后增大.摩擦过程中纯铜发生粘着磨损,铜-石墨复合材料却表现为剥层磨损.     

铜石墨复合材料改性研究进展

综述了铜石墨复合材料在改性方面进行的界面、添加剂和纤维增强等方面的研究.研究认为,界面改性、添加剂及纤维特别是纳米碳管等能显著提高铜石墨复合材料导电性能及摩擦磨损性能.     

Accelerated wear testing for evaluating the life characteristics of copper–graphite tribological composite

Sliding wear is a key determinant of the performance of electrical sliding contacts used in electrical machines. The behavior of the contact in sliding couple is controlled by the mutual metal transfer, friction and wear. Product life and reliability of sliding contacts are dictated by wear phenomenon. The present paper focuses on evaluation of tribological performance of copper–graphite composites using reliability theory. These composites are made up of a high electrical and thermal conductivity matrix with a solid lubricant reinforcement, making it most suitable for sliding contacts. Traditional life tests under normal operating condition would be a time consuming process due to a very long expected life of the composite. Hence, accelerated wear testing was carried out for evaluating the life characteristics. Analysis was then performed on the times-to-failure data and reliability models were developed. Life-stress relationship based on the inverse power law-Weibull model was used to make reliability predictions at normal usage level.     

Friction characteristics of aluminium silicon carbide graphite hybrid composites

Hybrid aluminum metal matrix composites reinforced with silicon carbide (SiC) and graphite (Gr) are extensively used due to high strength and wear resistance. Friction behavior of such hybrid composites is quite vital in deciding the optimal combination of SiC and Gr. The sliding friction response of stir cast hybrid aluminum composites reinforced with equal weight fraction of SiC and Gr particulates of 2.5%, 5%, 7.5% and 10% reinforcement is investigated. The influence of % reinforcement, load, sliding speed and sliding distance on friction coefficient is studied using pin-on-disk equipment with tests based on design of experiments. Hardness of the composites decreases with increase in % reinforcement. Friction coefficient is influenced by sliding speed as well as load and its average value is around 0.269. But, % reinforcement and sliding distance do not affect the friction coefficient.     

Thermal-Diffusivity Measurements of Conductive Composites Based on EVA Copolymer Filled With Expanded and Unexpanded Graphite

In this research, the thermal diffusivity of composites based on ethylene- vinyl acetate (EVA) copolymer filled with two kinds of reinforcement graphite materials was investigated. The reinforcement graphite fillers were untreated natural graphite (UG) and expanded graphite (EG). Composite samples up to 29.3 % graphite particle volumetric concentrations (50 % mass concentration) were prepared by the melt- mixing process in a Brabender Plasticorder. Upon mixing, the EG exfoliates in these films having nanosized thicknesses as evidenced by TEM micrographs. Thus, the thermal diffusivity and electrical conductivity of composites based on the ethylene-vinyl acetate matrix filled with nanostructuralized expanded graphite and standard, micro-sized graphite were investigated. From the experimental results it was deduced that the electrical conductivity was not only a function of filler concentration, but also strongly dependent on the graphite structure. The percolation concentration of the filler was found to be (15 to 17) vol% for micro-sized natural graphite, whereas the percolation concentration of the filler in nanocomposites filled with expanded graphite was much lower, about (5 to 6) vol%. The electrical conductivity of nanocomposites was also much higher than the electrical conductivity of composites filled with micro-sized filler at similar concentrations. Similarly, the values of the thermal diffusivity for the nanocomposites, EG-filled EVA, were significantly higher than the thermal diffusivity of the composites filled with micro-sized filler, UG-filled EVA, at similar concentrations. For 29.3 % graphite particle volumetric concentrations, the thermal diffusivity was 8.23 × 10^?7 m² · s^?1 for EG-filled EVA and 6.14 × 10^?7 m² · s^?1 for UG-filled EVA. The thermal diffusivity was measured by the flash method.     

Graphene-reinforced metal matrix nanocomposites – a review

The research works of graphene-reinforced metal matrix composites will be summarised in this paper. Comparatively, much less research works have been undertaken in this field. Graphene has been thought to be an ideal reinforcement material for composites due to its unique two-dimensional structure and outstanding physical and mechanical properties. It is expected to yield structural materials with high specific strength or functional materials with exciting thermal and electrical characteristics. This paper will introduce all kinds of graphene-reinforced metal matrix composites that have been studied. The microstructure and mechanical properties, processing techniques, graphene dispersion, strengthening mechanisms, interfacial reactions between graphene and the metal matrix and future research works in this field will be discussed.     

Enhancing the mechanical–electrical property simultaneously in pure copper composites by using carbonized polymer dots

In the development of copper-based composite materials, the dilemma of improving the mechanical properties without affecting the electrical properties is an important issue that must be solved. Here, carbonized polymer dot (CPD), as a novel reinforcement, was employed to fabricate CPD/Cu (pure copper) composite via powder metallurgy technique for the first time. The microstructure analysis revealed that the CPD was uniformly dispersed in the copper matrix in the form of nanoclusters, and the nanoclusters of CPD are composed of a three-dimensional amorphous carbon (AC) network structure and inserted carbon dots (some of them have a typical graphene structure, while others not). More importantly, excellent interface combination between the CPD and copper matrix is observed due to the existing of plenty of chemical functional groups. Based on this special microstructure, our prepared CPD/Cu composite achieves excellent mechanical and electrical conductivity simultaneously. Compared to pure Cu, the ultra-tensile strength of 0.2CPD/Cu composite is increased by about 17.0%, while the elongation is only?~?2% lower. The electrical conductivity of the composite is?~?98% IACS, which is much higher than that of pure copper prepared under the same condition (only?~?92% IACS). New insights into how to prepare advanced copper matrix composites with simultaneously improved overall performance will be found from our research.