Ceramic particles reinforced copper matrix composites manufactured by advanced powder metallurgy:preparation, performance, and mechanisms

Copper matrix composites doped with ceramic particles are known to effectively enhance the mechanical properties,thermal expansion behavior and high-temperature stability of copper while maintaining high thermal and electrical conductivity.This greatly expands the applications of copper as a functional material in thermal and conductive components,including electronic packaging materials and heat sinks,brushes,integrated circuit lead frames.So far,endeavors have been focusing on how to choose suitable ceramic components and fully exert strengthening effect of ceramic particles in the copper matrix.This article reviews and analyzes the effects of preparation techniques and the characteristics of ceramic particles,including ceramic particle content,size,morphology and interfacial bonding,on the diathermancy,electrical conductivity and mechanical behavior of copper matrix composites.The corresponding models and influencing mechanisms are also elaborated in depth.This review contributes to a deep understanding of the strengthening mechanisms and microstructural regulation of ceramic particle reinforced copper matrix composites.By more precise design and manipulation of composite microstructure,the comprehensive properties could be further improved to meet the growing demands of copper matrix composites in a wide range of application fields.

Fabrication of homogeneously dispersed graphene/Al composites by solution mixing and powder metallurgy

Graphene-reinforced aluminum （AI） matrix composites were successfully prepared via solution mixing and powder metallurgy in this study. The mechanical properties of the composites were studied using microhardness and tensile tests. Compared to the pure Al alloy, the graphene/Al composites showed increased strength and hardness. A tensile strength of 255 MPa was achieved for the graphene/Al com- posite with only 0.3wt% graphene, which has a 25% increase over the tensile strength of the pure Al matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to investigate the morphol- ogies, chemical compositions, and microstructures of the graphene and the graphene/A1 composites. On the basis of fractographic evidence, a relevant fracture mechanism is proposed.

Synthesis and Tribological Properties of Graphene-Copper Nanoparticle Composites as Lithium Grease Additive

In this paper, the graphene-copper nanoparticle composites(GN/Cu NPs) were prepared by in situ chemical reduction in aqueous solution. The influence of pH value and the concentration of PVP on the particle size and structure of the GN/Cu NPs as well as the element distribution were analyzed via the scanning electron microscopy(SEM), the transmission electron microscopy(TEM), the X-ray diffraction(XRD), and the energy dispersive spectroscopy(EDS). The tribological properties of the grease with GN/Cu NPs composites have been studied by SRV-IV. It was found that compared to the base grease, the GN/Cu NPs composites could help to reduce the wear loss of the disk by 85.5% and the average friction coefficient by 15.5%. The test results clearly indicated that the addition of the GN/Cu NPs composites significantly enhanced the tribological properties of grease.

Effect of graphene nanoplatelets(GNPs)addition on strength and ductility of magnesium-titanium alloys

Effect of graphene nanoplatelets(GNPs)addition on mechanical properties of magnesium–10wt%Titanium(Mg–10Ti)alloy is investigated in current work.The Mg-(10Ti+0.18GNPs)composite was synthesized using the semi powder metallurgy method followed by hot extrusion.Microstructural characterization results revealed the uniform distribution of reinforcement(Ti+GNPs)particles in the matrix,therefore(Ti+GNPs)particles act as an effective reinforcing filler to prevent the deformation.Room temperature tensile results showed that the addition of Ti+GNPs to monolithic Mg lead to increase in 0.2%yield strength(0.2%YS),ultimate tensile strength(UTS),and failure strain.Scanning Electron Microscopy(SEM),Energy-Dispersive X-ray Spectroscopy(EDS)and X-Ray Diffraction(XRD)were used to investigate the surface morphology,elemental dispersion and phase analysis,respectively.

Preparation and characterization of molybdenum powders with copper coating by the electroless plating technique

Molybdenum powders with a diameter of approximately 3 μn were coated with copper using the electroless plating technique in the pH 12.5-13 and temperature range of 55-75℃. The optimization of the electroless copper bath was evaluated through the combination of process parameters like pH and temperature. The optimized values ofpH and temperature were found to be 12.5 and 60℃, respectively, which attributes to the bright maroon color of the coating with an increase in weight of 46%. The uncoated and coated powders were subjected to microstructural studies using scanning electron microscope （SEM） and the phases were analyzed using X-my diffrction （XRD）. An attempt was made to understand the growth mechanism of the coating. The diffusion-shrinkage autocatalytic model was suggested for copper growth on the molybdenum surface.

Microstructure and Mechanical Performance of Cu-SnO_2-rGO based Composites Prepared by Plasma Activated Sintering

A novel chemical technique combined with unique plasma activated sintering（PAS） was utilized to prepare consolidated copper matrix composites（CMCs） by adding Cu-SnO2-rGO layered micro powders as reinforced fillers into Cu matrix. The repeating Cu-SnO2-rGO structure was composed of inner dispersed reduced graphene oxide（r GO）, SnO2 as intermedia and outer Cu coating. SnO2 was introduced to the surface of rGO sheets in order to prevent the graphene aggregation with SnO2 serving as spacer and to provide enough active sites for subsequent Cu deposition. This process can guarantee rGO sheets to suffi ciently disperse and Cu nanoparticles to tightly and uniformly anchor on each layer of rGO by means of the SnO2 active sites as well as strictly control the reduction speed of Cu^2＋. The complete cover of Cu nanoparticles on rGO sheets thoroughly avoids direct contact among rGO layers. Hence, the repeating structure can simultaneously solve the wettability problem between rGO and Cu matrix as well as improve the bonding strength between rGO and Cu matrix at the well-bonded Cu-SnO2-rGO interface. The isolated rGO can effectively hinder the glide of dislocation at Cu-rGO interface and support the applied loads. Finally, the compressive strength of CMCs was enhanced when the strengthening effi ciency reached up to 41.

Tribological properties of copper matrix composites reinforced with homogeneously dispersed graphene nanosheets

Graphene reinforced copper matrix composites （Gr/Cu） were fabricated by electrostatic self-assembly and powder metallurgy. The morphology and structure of graphene oxide, graphene oxide-Cu powders and Gr/Cu composites were characterized by scanning electronic microscopy, transmission electronic microscopy, X-ray diffraction and Raman spectroscopy, respectively. The effects of graphene contents, applied loads and sliding speeds on the tribological behavior of the composites were investigated. The results indicate that the coefficient of friction of the composites decreases first and then increases with increasing the graphene content. The lowest friction coefficient is achieved in 0.3 wt~ Gr/Cu composite, which decreases by 65% compared to that of pure copper. The coefficient of friction of the composite does not have significant change with increasing the applied load, however, it increases with increasing the sliding speed. The tribological mechanisms of the composite under different conditions were also investigated.

Mechanical and tribological properties of graphene nanoplatelets-reinforced titanium composites fabricated by powder metallurgy

Titanium matrix composite reinforced by graphene nanoplatelets(GNPs)was fabricated via powder metallurgy route.Hot isostatic pressing and hot extrusion were used to consolidate the mixed powder of GNPs and TC4 titanium(Ti)alloy.The microstructures,mechanical properties and sliding wear performance of Ti/GNPs composite had been researched to evaluate the rein forcing effect of GNPs on tita nium matrix.Microstructure observation indicates that GNPs could restrain grai n growth slightly in titanium matrix.Titanium matrix and graphene exhibit a clean and firm interface formed by means of metallurgical bonding on atomic scale.Compared with the monolithic titanium alloy,the composite with 1.2 vol.%GNPs exhibits significantly improved elastic modulus and strength.The sliding wear test shows that there is an obvious enhancement in the tribological performance of Ti/GNPs composite with 1.2 vol.%GNPs.The results of this work indicate that GNP is an efficient reinforcenient material in titanium matrix.The strengthening mechanism including precipitates strengthening,load transfer and grain refinement mechanism of GNPs in titanium matrix was discussed.A modified shear-lag model was used to analyze the reinforcement contribution of the stress transfer mechanism.The calculation shows that the stress load mechanism constitutes the main strengthening mechanism in Ti/GNPs composite.

An approach to prepare uniform graphene oxide/aluminum composite powders by simple electrostatic interaction in water/alcohol solution

The homogenous dispersion of graphene in Al powders is a key challenge that limits the development of graphene-reinforced metal matrix composites with high performance.Here,uniform distribution of graphene oxide(GO)coated on flake Al powders were obtained by a simply stirring and ultrasonic treatment in the water/alcohol solution.The effect of water volume content on the formation of GO/Al composite powders was investigated.The results showed that GO adsorbed with synchronous reduction on the surface of Al powders,but when the water content was higher than 80%in the solution,Al powders were totally changed into Al(OH)3.With optimizing the water content of 60%in the solution,reduced GO was homogenously coated onto the surface of flake Al powders.The formation mechanism can be ascribed to the balance control between the liquid/solid interaction and the hydrolysis reaction.

电爆法制备石墨烯及其铜基复合涂层的性能研究

石墨烯与金属粉末混合后容易团聚,不能有效均匀分散,无法充分发挥其优异特性。为解决石墨烯在复合材料中的团聚问题,采用自主研制的电爆设备制备了石墨烯气溶胶,将其与铜粉混合得到石墨烯/铜复合粉体,并制备出石墨烯/铜复合涂层。使用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和原子力显微镜(AFM)对石墨烯气溶胶及复合材料进行表征分析,并测试涂层的硬度和耐磨性。结果表明,电爆法制备的石墨烯主要为小片径石墨烯,片径尺寸为5~40 nm,层数为3~7层。在浓度0.875 mg/L的石墨烯气溶胶中,衬底放置时间少于10 min时,单个的小片径石墨烯片碰撞吸附在衬底上,未发现凝并后的石墨烯气溶胶凝胶;衬底放置时间超过10 min后,许多小片径石墨烯堆叠在一起,形成石墨烯气溶胶凝胶,且衬底放置时间越长,凝并越严重,石墨烯气溶胶凝胶团也在不断长大。石墨烯/铜复合粉体中小片径石墨烯均匀吸附在铜粉表面,制备出的复合涂层其表面C元素分布均匀,有效解决了团聚问题。0.5 wt.%石墨烯/铜涂层平均硬度为74.8 HV0.05、摩擦系数为0.18,与纯铜涂层相比均有不同程度的提升。结果表明,电爆法制备的石墨烯气溶胶可用于制备石墨烯/铜复合涂层,提高涂层的硬度和耐磨性。该方法有望为制备高性能石墨烯/金属复合材料提供新的途径。

壳核结构氧化铝@石墨烯复合粉末增强铜基复合材料摩擦学性能研究

如何充分发挥润滑组元和耐磨组元的协同作用以提高铜基复合材料摩擦学性能仍面临具大的挑战。以石墨烯为润滑组元,氧化铝为耐磨组元,对比了氧化铝和石墨烯组装为壳核结构前后对铜基复合材料摩擦学性能的影响。结果表明,与氧化铝和石墨烯分别以独立相分布于铜基体的情况相比,氧化铝和石墨烯组装为壳核结构后可以提高铜基复合材料的致密度、硬度,并有利于在磨痕表面形成连续且具有保护性的摩擦层。因此,在10~40 N载荷范围内干摩擦,后者比前者具有更低的摩擦因数和磨损率。

石墨烯化学镀铜对放电等离子烧结石墨烯增强铝基复合材料组织和性能的影响

通过化学镀方法得到镀铜石墨烯粉末,再通过静电自组装方法将镀铜石墨烯粉末与铝粉混合,然后经放电等离子烧结工艺制备镀铜石墨烯增强铝基复合材料,研究了不同质量分数(0.1%,0.2%,0.3%,0.4%,0.5%)镀铜石墨烯增强铝基复合材料的微观结构和性能,并与质量分数0.1%未镀铜石墨烯增强铝基复合材料进行对比。结果表明:镀铜石墨烯在复合材料中分散均匀,复合材料的相对密度均在99%以上;铝和铜发生反应生成了中间相Al_(2)Cu,但未有Al_(4)C_(3)界面相生成;镀铜石墨烯增强铝基复合材料的硬度和耐磨性能均优于未镀铜石墨烯增强铝基复合材料;随着镀铜石墨烯含量的增加,复合材料的硬度先升高后降低,磨损质量损失和摩擦因数均呈先减小后增加的趋势。当镀铜石墨烯的质量分数为0.2%时,复合材料具有优异的综合性能,其硬度为74.7 HV,磨损质量损失和摩擦因数均最小,分别为0.0023 g和0.259,磨损机制为氧化磨损。

原位生长CNTs对于铜基复合材料性能的影响

通过化学气相沉积(chemical vapor deposition,CVD)法成功制备了CNTs/Cu-Al_(2)O_(3)复合材料。采用内氧化法制备Cu-Al_(2)O_(3)粉末,利用CVD技术改善碳纳米管(carbon nanotubes,CNTs)在铜基体中的分散性和界面结合,提高复合材料的性能。在制备的铜基复合材料中,Al_(2)O_(3)和CNTs双增强相的加入能够提高复合材料的力学性能,且CNTs独特的纤维结构有助于阻止熔融铜脱离基体表面,保持液态熔池稳定,避免复合材料导电率降低。双增强相的添加提高了复合材料的耐磨性、抑制了腐蚀坑的形成。Al的质量分数为0.35%的CNTs/Cu-Al_(2)O_(3)复合材料能够保证导电率较高的情况下得到较高的维氏硬度与致密度。为制备高性能铜基电接触材料提供了新思路。

基体铬合金化增强石墨烯/铜复合材料摩擦学性能研究

如何通过优化石墨烯/铜复合材料的界面结构来提高复合材料的摩擦学性能成为石墨烯增强铜基复合材料领域重要的研究方向之一。采用铜铬合金(CuCr)作为基体材料,还原氧化石墨烯(RGO)作为增强相,通过溶液搅拌混合和热压烧结工艺制备得到了RGO/CuCr复合材料。对比了添加铬元素前后复合材料的减摩耐磨性能,基于磨痕表面成份和形貌的分析探讨了铜基体铬合金化对石墨烯/铜复合材料摩擦学性能的作用机制。结果表明,铜基体铬合金化使复合材料具有更小更稳定的摩擦因数和更低的比磨损率,特别是在高载荷工况下。性能提高的原因归结为铜基体铬合金化有利于在摩擦过程中复合材料表面形成致密而连续的富石墨烯摩擦层。

氧化石墨烯负载氧化铈对铜基复合材料性能的影响

为了提高铜基复合材料的综合性能,本试验设计了三种高强度、高导电性的电触头材料。将氧化石墨烯(GO)和CeO_(2)纳米粒子优良的电学和力学性能引入到电接触性能稳定的铜基复合材料中,采用放电等离子烧结(SPS)的方法制备了Cu/30Cr、0.5GO/CeO_(2)-Cu/30Cr、1.0GO/CeO_(2)-Cu/30Cr三种电触头材料,研究氧化石墨烯负载氧化铈对铜基复合材料性能的影响。研究结果显示在烧结过程中,GO被还原为rGO,原位形成的Cr_(3)C_(2)和CeO_(2)纳米颗粒的位错钉扎效应对材料起到了强化作用,氧化石墨烯负载氧化铈的加入提高了复合材料的综合性能。

基于分子动力学模拟的铜-石墨烯复合材料耐烧蚀性能提升方法

直线推进机构的轨道因滑动电弧烧蚀严重易导致发射失败,研究新的耐烧蚀金属材料是提高发射效率的关键,目前鲜有性能优异的铜-石墨烯复合材料(CuGr)在极端工况下滑动电弧烧蚀的研究。该文对石墨烯层叠式分布CuGr模型进行分子动力学模拟,揭示模拟烧蚀中模型表层温度和材料微观结构的演变规律,并提出石墨烯在材料中合适的掺杂方式。结果表明:石墨烯质量分数越高,层数越少,CuGr导热性能越好。石墨烯能有效的减少轰击最大侵入距离。基体中石墨烯也可阻挡位错深入,不引起反尺寸效应时石墨烯层数越多,质量分数越大,应变残留深度越小。石墨烯可以降低最终侵蚀坑的深度和减少基体材料的质量损失,CuGr模型的侵蚀坑深度类似,质量损失方面各模型相差较小但随着层数增加呈现减小趋势,且都优于Cu模型。综合对比模拟结果,效果最优的是石墨烯6层分布Cu Gr1%。上述结果可揭示铜-石墨烯复合材料耐烧蚀作用规律和微观机理,为制备耐烧蚀性能更高的CuGr材料提供理论依据和技术支持。

CVD合成三维石墨烯-铜复合材料及其超高导电性(英文)

石墨烯-铜复合材料具有广阔的应用前景。然而,具有超高导电性的石墨烯-铜复合材料仍未成功开发和应用。本研究利用铜粉烧结内部形成三维微孔,并通过化学气相沉积(CVD)法合成石墨烯-铜异质结构。将其挤压成直径为4 mm的铜-石墨烯复合线材,测量了其在室温和高温下的电导率,获得了导电率(101.0%IACS)高于国际退火铜(100%IACS)的铜-石墨烯复合材料,且石墨烯-铜复合导线的高温载流量比纯铜线高5.45%。本研究为获得超高导电性铜基复合材料提供了新的思路。

石墨烯增强铜复合材料摩擦性能研究

通过原位合成石墨烯结合粉末烧结法制备了石墨烯增强铜复合材料,然后在空气环境中研究石墨烯增强铜复合材料的摩擦性能。实验选用直径为6 mm的WC磨球与复合材料组成摩擦副,利用摩擦磨损试验机对材料进行摩擦磨损测试。采用SEM、EBSD、EDS和三维轮廓形貌仪等相关检测设备对复合材料的微观组织结构以及磨损的表面形貌结构进行分析表征。结果表明,相比于纯铜材料,石墨烯增强铜复合材料具有更低的摩擦系数,这主要归功于复合材料较高的硬度以及石墨烯的自润滑效应。最后结合复合材料的磨损形貌给出了相关的磨损机制。

有机硅单体合成用复合铜粉催化剂的研究

采用硅粉与氯甲烷,于直管式固定搅拌床反应器中合成甲基氯硅烷,通过计算二甲基二氯硅烷(M2)的选择性和硅转化率,评价3种复合铜催化剂的催化性能。结果表明,自产复合铜粉C的催化性能相对较佳,采用复合铜粉C的体系在整个反应期间的M2选择性均值为91.89%,硅转化率为59.24%。复合铜粉C具有更薄、更细、比表面积更高、松装密度更低、粒度更细的特点,有利于其在甲基氯硅烷合成反应中与硅粉形成更多的活性中心。