Synergistic regulation of current-carrying wear performance of resin matrix carbon brush composites with tungsten copper composite powder

Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flake graphite powders that were evenly loaded with tungsten copper composite powder(RMCBCs-W@Cu)exhibited a low wear rate of 1.63 mm^(3)/h,exhibiting 48.6%reduction in the wear rate relative to RCMBCs without additives(RMCBCs-0).In addition,RMCBCs-W@Cu achieved a low friction coefficient of 0.243 and low electric spark grade.These findings indicate that tungsten copper composite powders provide particle reinforcement and generate a gradation effect for the epoxy resin(i.e.,connecting phase)in RMCBCs,which weakens the wear of RMCBCs caused by fatigue under a cyclic current-carrying wear.

Effect of sintering parameters on the microstructure and thermal conductivity of diamond/Cu composites prepared by high pressure and high temperature infiltration

Pure Cu composites reinforced with diamond particles were fabricated by a high pressure and high temperature （HPHT） infiltration technique. Their microstructural evolution and thermal conductivity were presented as a function of sintering parameters （temperature, pressure, and time）. The improvement in interfacial bonding strength and the maximum thermM conductivity of 750 W/（m.K） were achieved at the optimal sintering parameters of 1200℃, 6 GPa and 10 min. It is found that the thermal conductivity of the composites depends strongly on sintering pressure. When the sintering pressure is above 6 GPa, the diamond skeleton is detected, which greatly contributes to the excellent thermal conductivity.

A review of processing of Cu/C base plate composites for interfacial control and improved properties

The increase in both power and packing densities in power electronic devices has led to an increase in the market demand for effective heat-dissipating materials with a high thermal conductivity and thermal expansion coefficient compatible with chip materials while still ensuring the reliability of the power modules.Metal matrix composites,especially copper matrix composites,containing carbon fibers,carbon nanofibers,or diamond are considered very promising as the next generation of thermalmanagement materials in power electronic packages.These composites exhibit enhanced thermal properties,as compared to pure copper,combined with lower density.This paper presents powder metallurgy and hot uniaxial pressing fabrication techniques for copper/carbon composite materials which promise to be efficient heat-dissipation materials for power electronic modules.Thermal analyses clearly indicate that interfacial treatments are required in these composites to achieve high thermal and thermomechanical properties.Control of interfaces(through a novel reinforcement surface treatment,the addition of a carbide-forming element inside the copper powders,and processing methods),when selected carefully and processed properly,will form the right chemical/mechanical bonding between copper and carbon,enhancing all of the desired thermal and thermomechanical properties while minimizing the deleterious effects.This paper outlines a variety of methods and interfacial materials that achieve these goals.

增强体表面改性在高导热金属基复合材料中的应用

随着电子技术的高速发展和电子器件的更新换代,电子封装材料的性能需求越来越高。金属基复合材料,尤其是铝基和铜基复合材料具有高导热、低膨胀、高稳定性等特点,是具有广阔应用前景的电子封装材料。然而,金刚石、石墨烯、硅等增强体与基体的润湿性差,或者在高温下与基体发生有害的界面反应,限制了此类高导热金属基复合材料的开发和应用。本文简述了金属基复合材料的界面研究进展,结合影响金属基复合材料界面结合的因素,提出了几种改善界面结合的方法。增强体表面改性是改善金属基复合材料界面的重要途径之一,常用工艺有磁控溅射法、化学气相沉积法、溶胶凝胶法、化学镀法等;最后,对增强体表面改性在高热导金属基复合材料中的应用进行分析和展望。

Distribution and engulfment behavior of TiB_2 particles or clusters in wedge-shaped copper casting ingot

Wedge-shaped copper casting experiment was conducted to study the engulfment behavior of TiB2 particle and the interaction between particle or cluster and the solid/liquid front in commercial pure aluminum matrix. The experimental results show that the particle size distribution obeys two separate systems in the whole wedge-cast sample. Furthermore, it is found that the big clusters are pushed to the center of the wedge shaped sample and the single particle or small clusters consisting of few particles are engulfed into the α-Al in the area of the sample edge. The cluster degree of particles varies in different areas, and its value is 0.2 and 0.6 for the cluster fraction in the edge and in the center of the wedge sample, respectively. The cluster diameter does not obey the normal distribution but approximately obeys lognormal distribution in the present work. More importantly, in the whole sample, the particle size obeys two separate log-normal distributions.

颗粒增强铜基复合材料的研究现状与发展趋势

铜及铜合金具有优异的导电、导热和延展性,但是较差的力学性能限制了其在工业领域中的进一步应用,而复合化被认为是提升其综合性能的有效途径之一。总结了颗粒增强铜基复合材料常见增强相的选择依据,综述了颗粒增强铜基复合材料的制备方法、影响其性能的关键因素以及性能调控措施,最后结合制备方法中存在的问题对未来研究方向提出了一些新思路。

石墨烯增强铜基复合材料制备工艺及性能的研究进展

作为常用的金属材料,铜因强度较低而应用范围受限,石墨烯具有优异的综合性能,作为极具潜力的增强体而受到广泛关注。石墨烯增强铜基复合材料兼具了铜和石墨烯的优良性能而成为了重要的研究对象。介绍了石墨烯增强铜基复合材料的制备工艺与综合性能,重点讨论了各种制备工艺的特点、强化机制、构型设计,总结了针对复合界面结合弱与石墨烯分散困难这2类主要技术难点的解决途径,最后对石墨烯增强铜基复合材料的制备工艺进行了展望。

球形Cu粉粒径对谐波结构TiB_(2)/Cu复合材料组织及性能的影响

以Cu-Ti-B体系为研究对象,利用球磨和振动混粉方法进行构型设计,通过热压烧结制备出TiB_(2)富集区(硬区)包裹纯Cu区(软区)的谐波结构TiB_(2)/Cu复合材料。研究了球形Cu粉粒径对谐波结构复合材料微观组织、传导性能和力学性能的影响。结果显示:当球形Cu粉粒径较小时,谐波结构特征不明显,且强塑性较差。当球形Cu粉粒径大于15μm时,谐波结构特征逐渐显著。当Cu粉粒径在53~75μm时,谐波结构复合材料的致密度和传导性能最优,同时TiB_(2)富集区与纯Cu区之间的不兼容变形有助于在纯Cu区产生背应力使其强化,并在TiB_(2)富集区产生相应的正应力使其韧化,背应力与正应力的共同作用使谐波结构TiB_(2)/Cu复合材料发挥较好的协调变形能力,获得更优的强塑性匹配。随着球形Cu粉粒径进一步增加,复合材料的强塑性逐渐降低。因此,在谐波结构复合材料中,调控合适的非均匀组织特征对复合材料综合性能至关重要。

Study of metal-ceramic WC/Cu nano-wear behavior and strengthening mechanism

In view of the inherent poor tribological properties of copper,the reinforcement of copper matrix composites with WC particles presents a promising research area with significant industrial influence.Therefore,in the present study,a molecular dynamics approach is used to simulate the process of repeated friction of diamond grinding balls on WC/Cu composites,and the friction force,friction coefficient,abrasion depth,wear rate,abrasion morphology,von-Mises stress,internal defects,workpiece energy,and performance comparison of different layer thicknesses are systematically investigated in the multiple friction process.It is found that the fluctuation amplitude of friction force,friction coefficient,and abrasion depth are smaller and the fluctuation frequency is larger during the initial friction,whereas near the WC phase,there appears extreme values of the above parameters and the von-Mises stress is highly concentrated while the workpiece energy contonues to increase.In the case of the repeated friction,with the increase of friction times,the friction force,friction coefficient,and abrasion depth fluctuation amplitude increase,the fluctuation frequency decreases,the workpiece energy reaches an extreme value near the WC phase,and a large number of dislocations plug,therefore,the region is strengthened.As the distance between the grinding ball and the WC phase decreases,the more obvious the strengthening effect,the stronger the ability of workpiece to resist the wear will be.

AA1050表面Al-Mg-Cu_((p))复合涂层的力学和摩擦学性能

研究添加铜粉和改变耗材转速对AA1050铝合金基体上摩擦堆焊Al-Mg涂层力学和摩擦学性能的影响。铜粉是通过在耗材的横截面上钻孔的方式嵌入的。用光学显微镜和电子显微镜研究涂层的显微组织,用剪切实验研究涂层的力学性能。结果表明,当耗材转速从600 r/min增加到1000 r/min时,铜粉分布更加均匀,铜粉团聚现象减少,涂层的平均晶粒尺寸从(2.0±0.1)μm减小到(0.9±0.2)μm。随着转速的增加,富铜颗粒变小,并形成CuAl_(2)金属间化合物。当耗材转速从600 r/min增加到1000 r/min,使涂层从基体剥离所需的最大力从16.2 kN增加到18.4kN。转速为600、800和1000 r/min制备的涂层其磨损率分别比AA1050基材的低12%、18%和21%。

碳纤维-铜复合材料研究

综述了碳纤维-铜基复合材料的发展历程,总结了目前国内外对碳纤维-铜基复合材料的制备工艺与性能的研究进展,展望了碳纤维-铜基复合材料在我国的发展趋势和前景.

碳纤维增强铜基复合材料的最新研究进展和应用

碳纤维增强铜基复合材料是一种极具发展前途的金属基复合材料。介绍了碳纤维增强铜基复合材料的制备工艺,总结概述了目前短碳纤维增强铜基复合材料的物理力学性能研究进展及其在航空航天、汽车、电子方面的应用现状和前景。探讨分析了碳纤维增强铜基复合材料的研究开发趋向,对碳纤维增强铜基复合材料的研究开发和实际应用具有一定的指导意义。

陶瓷颗粒增强铜基复合材料研究进展

概述了目前研究最为广泛,最具有应用前景的SiC、Al2O3、AlN和Ti3SiC2颗粒增强铜基复合材料在制备及性能特点方面的研究现状,以及陶瓷颗粒增强铜基复合材料常用的制备方法。

氧化铝颗粒增强铜基复合材料

在纯铜粉末冶金工艺的基础上，系统地研究和分析了氧化铝对复合材料组织、性能的影响．在烧结过程中，弥散分布于铜基体中的氧化铝颗粒对致密化以及晶粒长大都有阻止作用．随着复合材料中氧化铝含量的增加，材料的密度、导电性呈下降趋势，而硬度出现极大值．当氧化铝含量为１％左右时材料的导电性和机械性能达到较好的配合．

纳米Cu-Al_2O_3复合材料的烧结法制备研究

研究了纳米Al2 O3陶瓷颗粒增强铜基复合材料制备技术。选用纳米级Al2 O3陶瓷颗粒作为增强相 ,采用超声波增强化学镀的方法完成对纳米Al2 O3陶瓷颗粒金属铜包覆 ,热压烧结成纳米Al2 O3陶瓷颗粒增强铜基复合材料 ,开采用XRD、TEM等分析测试技术对其组织性能进行研究。

镀铬碳纤维增强铜基复合材料的组织与性能

以镀铬碳纤维和铜粉为原料,采用粉末冶金方法制备碳纤维增强铜基体复合材料,用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、聚焦离子束(FIB)、电子天平、数字金属电导率测量仪以及硬度计对碳纤维及复合材料进行显微组织及力学性能的研究,并探讨碳纤维体积分数对复合材料性能的影响。结果表明:碳纤维在铜基体上分布均匀,基体组织致密,随碳纤维体积分数增加,复合材料密度逐渐降低,且复压复烧后材料密度提高,复合材料的密度在碳纤维体积分数为1%时达到最大值(8.640 9 g/cm3);复合材料的硬度值先增加后减小,复压复烧后,碳纤维体积分数为5%时硬度达到最大值(50.6HV);随碳纤维体积分数增加至15%,导电率逐渐减小至75.8%IACS。

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.

Al_2O_3/Cu复合材料的微动摩擦学特性

以纳米Al2O3为增强相,用粉末冶金法制备了铜基复合材料,研究了Al2O3的比例、载荷等对复合材料摩擦因数和磨损量的影响,并和纯铜的性能作了比较。结果表明,Al2O3的质量分数不宜超过4%,以2%为最佳;纯铜的摩擦因数随着载荷的增加而轻微上升,但Cu/Al2O3复合材料的摩擦因数随着载荷的增加变化幅度较大,呈先上升后下降的趋势,且在极小和较大的载荷下,复合材料的摩擦因数均比纯铜低,但复合材料的磨损量始终比纯铜的低,相对耐磨性最高可达1.55,呈现出良好的耐磨性。

纤维状态对碳纤维-铜基复合材料性能的影响

以电解铜粉和碳纤维等为原料,采用冷压烧结法制备碳纤维-铜基复合材料并研究了纤维质量分数、纤维长度以及纤维电镀等对其性能的影响。结果表明,1）碳纤维-铜基复合材料的相对密度和导电性能都随着纤维质量分数的增加不断下降,强度和耐磨性却随着纤维质量分数的增加先上升后下降,当碳纤维质量分数在3.0%~4.5%之间时,复合材料具有较好的综合性能。2）随着纤维长度的增加,碳纤维-铜基复合材料的相对密度、导电性和耐磨性等会由于孔隙率的升高和界面结构变差而下降,强度却随着纤维长度的增加而先上升后下降。3）与预镀镍相比,采用碳纤维预镀铜的方法制备的碳纤维-铜基复合材料,导电性能提高,机械性能下降。

碳纤维增强铜基复合材料的制备与性能

采用磁控溅射法在碳纤维表面制备了镀铬层,用以改善碳纤维与铜基体的润湿性;然后在1 200℃、4×10-1 Pa真空条件下,用纯铜液相浸渗碳纤维2h炉冷后制备了碳纤维增强铜基复合材料;采用扫描电镜、硬度仪对其显微组织及其力学性能进行了研究,并对其导电性能进行了测试。结果表明:采用溅射功率50W、溅射时间40min、气压2.0Pa、氩气流量为20mL·min-1的工艺,可在碳纤维表面制备厚度为400～500nm的铬层,镀铬层表面光亮,与碳纤维结合良好,无"黑心现象";复合材料中的碳纤维与铜基体的界面平整清晰,其轴向导电率达到了83%IACS,硬度为56.3HB,抗拉强度的推算值为303.457～404.768MPa。