碳化硅增强铝基复合材料界面改善对力学性能的影响

用粉末冶金法制备了致密度较好的镀铜碳化硅增强铝基复合材料,并对碳化硅的表面化学镀工艺进行了分析.通过化学镀前后复合材料力学性能的对比研究表明,碳化硅表面镀铜较好地解决了碳化硅与基体的相容性问题,使复合材料的力学性能得到明显提高.     

Cu-FeS复合材料导热性能的计算研究

为了研究质量分数为15%FeS的Cu-FeS自润滑材料内部结构与导热性能的关联, 采用分子动力学的方法, 在考虑界面热阻的情况下构建原子模型, 对增强相和复合材料导热性能进行模拟研究。结果表明: FeS在600K、 900K时会发生有利于热传导的结构变化, 系统界面热阻随着FeS尺寸的增大而减小, 颗粒大于100nm时, 界面热阻趋于一定值。通过计算所得导热率与实验数值较接近, 误差的引起是由于计算没有考虑温度升高对界面结合的破坏、 界面的不完整性、 基体内部缺陷、 弥散相的大小等因素。验证了HasselmanJohnson方法对于预测该复合材料的合理性。      

碳化硼颗粒增强Cu基复合材料的研究

研究了用表面涂覆含钛金属涂层的碳化硼颗粒增强Cu基复合材料[B4Cp/(TiB2 TiN)/Cu],并与未经涂覆的B4C颗粒增强Cu基复合材料（B4Cp/Cu)进行了对比。实验结果表明,前者的致密度和电导率比后者好。磨损实验结果表明,使用有涂层颗粒的复合材料的耐磨性比无涂层颗粒的好。通过对复合材料界面和磨损表面的电镜观察表明,B4C颗粒经过涂覆处理后,改善了复合材料的界面粘结性能,颗粒与基体间有良好的浸润性。     

Microstructure evolution and tribological properties for new AlSi9Cu3/5%GrCu composite

A metallic matrix composite, with AlSi9Cu3 matrix reinforced with 5% copper coated graphite (Gr_Cu) was processed in semi solid state by centrifugal casting. This technique allows the uniform controlled distribution of the reinforcing material to provide improved tribological properties in certain area. The graphite particles were copper coated for a better embedding in the matrix. The microstructure evolution revealed compounds containing Mn, Si and Mg in the matrix alloy and the final composite and controlled distribution of the copper coated graphite as reinforcing material. The hardness measurement showed 48% improvement towards the matrix alloy and the Young modulus showed 27% improvement. The friction coefficient and wear rate obtained revealed a very good and promising behavior of the composite processed in semi solid state for ball bearings ring application.     

Preparation of 3YSZ/Cu composite by in-situ chemical route

To improve electrical and mechanical properties of electrodes for contact welding, a 3 mol% yttria stabilized zirconia (3YSZ) to reinforced copper matrix composite was developed by an in-situ chemical process. The microstructure and properties of the in-situ composite were investigated. The results showed that in-situ nano-scale particles were uniformly dispersed in the copper matrix by dispersed nano-particle and its cluster. Due to their reinforcement, the hardness of the in-situ 3YSZ/Cu composite significantly increased. Moreover, the electrical conductivity of the in-situ composite decreased with the increase of 3YSZ content.     

碳毡／铜复合材料的制备及其物理性能研究

选用廉价的碳毡作为增强体，成功地摸索出用电沉积法制取碳毡／铜复合材料的工艺。研究了碳毡／铜复合材料的导电性能、热膨胀性能及电磁屏蔽性能。实验结果表明，该材料是一种较廉价且性能优越的新型功能复合材料。     

Computational assessment of the influence of load ratio on fatigue crack growth in fibre-reinforced metal matrix composites

A three-dimensional finite element model of a composite tensile specimen consisting of a Ti–6Al–4V matrix reinforced with unidirectional, continuous SiC fibres under cyclic loading has been developed. The model includes the fibre/matrix morphology, with the interface interaction being governed by the Coulomb friction law. The influence of the applied load ratio on the true crack-tip load ratio has been investigated for three different applied load ratios. The results from the model show that due to a combination of thermal residual stresses from processing and fibre bridging, the crack-tip load ratio becomes independent of the applied load ratio after a small amount of crack growth. With the fatigue threshold depending strongly on the load ratio, crack arrest occurs at a later stage than would be predicted from the applied load ratio.     

石墨烯负载铜增强铜基块体复合材料的制备及其性能

石墨烯具有独特的二维结构及性能已成为金属基复合材料制备过程中理想的增强相备选材料之一。而铜因具有良好的导热性、导电性和化学稳定性已被广泛应用到电子产品中,但其存在机械强度低、硬度低等缺点成为其应用亟需解决的瓶颈问题。目前,将石墨烯和铜基材料进行结合,虽然在一定程度上可以改善铜基材料的的综合性能。但由于石墨烯易产生团聚,石墨烯与铜之间的润湿性差,使其两者难以形成良好的界面结合,进而导致复合材料的性能变差。因此,为了解决上述问题,本文通过化学还原法在石墨烯上负载铜粒子对石墨烯进行改性处理,成功制备了石墨烯负载铜复合粉体(Cu-rGO),并将其作为增强相,与纳米铜粉混合,运用放电等离子烧结(SPS)工艺制备了石墨烯负载铜增强铜基块体复合材料(Cu-rGO/Cu),研究Cu-rGO复合粉体含量对铜基体组织和性能的影响。研究发现,在50 mg氧化石墨烯(GO)和200 mg硫酸铜(CuSO4·5H2O)时,获得Cu-rGO复合粉体中还原氧化石墨烯较薄且分布均匀。同时结合TEM结构分析发现铜基体与增强相接触界面紧密,且增强相的引入可以有效地细化块体复合材料的晶粒。另外,随着增强相含量的递增,硬度呈...     

Electroforming of TiB2-Reinforced Copper Matrix Electrode for EDM

TiB₂ particle-reinforced copper matrix composite is electroformed in copper sulfate on stainless steel plate. The impact of the particle content in electroforming solution on the surface morphology, hardness, and electrical conductivity of the electroformed composite are studied, and the influence of electroforming current density on the effective content of particles in the composite is also analyzed. The results show that when the content of particles in electroforming solution is 25 g/L, the current density is 4 A/dm², particles in the electroformed composite are well-distributed, and the average grain diameter can be reduced to 20 µm. The microhardness of Cu/TiB₂ composite reinforced by particles with diameter of 3 µm is 25% higher than that of electroformed copper, and its conductivity remains 86% of the copper.     

Synergistic electro-co-deposition and molecular mixing for reinforcement of multi-walled carbon nanotube in copper

Carbon nanotube-reinforced copper composite powder was prepared by a modified electro-co-deposition method that was carried out on small diameter (3 mm) tip of the cathode. The deposition was done at room temperature and atmospheric pressure. Samples were prepared under constant stirring by a magnetic stirrer. Transmission and scanning electron microscopy confirms the dispersion of multiwalled carbon nanotubes (MWCNT) in the copper matrix. Dispersion of MWCNTs in copper matrix by this method is very easy and the set up can be easily scaled up for the bulk production of MWCNT reinforced copper powder. The method for the fabrication of MWCNT reinforced copper powder; microstructure and morphology of the powder formed are reported.     

Effect of size and shape of metal particles to improve hardness and electrical properties of carbon nanotube reinforced copper and copper alloy composites

Utilizing the extra-ordinary properties of carbon nanotube (CNT) in metal matrix composite (MMC) for macroscopic applications is still a big challenge for science and technology. Very few successful attempts have been made for commercial applications due to the difficulties incorporating CNTs in metals with up-scalable processes. CNT reinforced copper and copper alloy (bronze) composites have been fabricated by well-established hot-press sintering method of powder metallurgy. The parameters of CNT–metal powder mixing and hot-press sintering have been optimized and the matrix materials of the mixed powders and composites have been evaluated. However, the effect of shape and size of metal particles as well as selection of carbon nanotubes has significant influence on the mechanical and electrical properties of the composites. The hardness of copper matrix composite has improved up to 47% compared to that of pure copper, while the electrical conductivity of bronze composite has improved up to 20% compared to that of the pure alloy. Thus carbon nanotube can improve the mechanical properties of highly-conductive low-strength copper metals, whereas in low-conductivity high-strength copper alloys the electrical conductivity can be improved.     

Werkstoffverhalten eines metallischen Faserverbundes und seiner Komponenten bei LCF‐Wechselbeanspruchung

Behaviour of a metallic fibre composite material and its components in LCF‐test The mechanical behaviour of unidirectional metallic fiber composite materials is investigated in the low cycle fatigue tests. The material consists of a copper matrix reinforced by continuous unidirectional fibers of austenitic steel with two different volume fractions. A comparative investigation carried out on the component materials. In addiction to the result of the strain controlled tension‐compression‐tests, the fatigue life is estimated using the Manson‐Coffin relation. The fracture characteristics are studies metallographically.     

碳纤维/铜纤维混编酚醛树脂基摩擦材料的制备及其弯曲性能

以碳纤维和铜纤维为原料制备了三维四层深交联机织物,并将酚醛树脂和其他填料组成树脂体系,然后将二者进行复合成型,制成三维深交联摩擦材料。通过改变织物纬向的铜纤维含量及位置获得四种深交联机织摩擦材料,探究不同位置和含量的铜纤维对摩擦材料纬向弯曲性能的影响。结果表明:摩擦材料的弯曲性能随着铜纤维含量的增加而减小;当铜纤维处在摩擦材料预制体中间层时,会降低复合材料的弯曲性能。材料的破坏模式具体表现为树脂基体的碎裂,以及纤维的抽拔及断裂。     

Strengthening mechanisms of aluminum matrix composite containing Cu-coated SiC particles produced by friction stir processing

ABSTRACT

A friction stir processing (FSP) method has been developed to fabricate a locally reinforced aluminum matrix composite (AMC) by stirring electroless-copper-coated SiC particles into AA6061 matrix. The interfacial bonding between particulate reinforcement and the matrix was enhanced by the copper coating. Effective improvement in hardness and in tensile strengths has been proved. Microstructural investigation and analyses were conducted to correlate the microstructural evidences with the possible strengthening mechanisms. The effect of copper coating on the bonding between SiC particles and Al-matrix; the role of the dispersed Cu debris and the increased Cu content in solid solution on the strengthening; and the effect of friction stir on dislocation density and on the recrystallization behavior were analyzed. Multiple strengthening mechanisms due to diffusion between copper film and matrix; dispersion of fine copper debris and Al-Cu intermetallic compounds (IMCs) in the matrix; solid solution due to increased copper content and dislocation punching were four major mechanisms in interpreting the strengthening phenomena in AMC containing copper coated SiC reinforcements.     

石墨烯增强铜基复合材料研究进展

石墨烯是一种新兴的二维碳纳米材料,具有良好的力学、导电以及润滑性能,是铜基复合材料中最具潜力的增强体.本文综述了石墨烯增强铜基复合材料的制备工艺,详细分析并归纳了石墨烯增强铜基复合材料的界面结构对于复合材料力学性能的影响及增强机制,总结了石墨烯增强铜基复合材料摩擦学行为研究的最新进展,并深入阐述了石墨烯增强铜基复合材料...     

碳纤维含量对短碳纤维-铜复合材料性能的影响

用粉末冶金法制造了碳纤维分布均匀的碳纤维一铜复合材料,测定了复合材料的力学性能和物理性能,表明在碳纤维与铜基体之间存在界面结合,碳纤维含量对复合材料性能影响极大。     

Influence of Fiber Orientation and Fillers on Low Velocity Impact Response of the Fabric Reinforced Epoxy Composites

The low velocity impact response of the epoxy composite materials, which were reinforced with various hybrid contents, such as plain pure or hybrid fabrics (carbon, aramid and glass fibers and copper wires) and filler mixtures into the epoxy matrix (aramid powder, potatoes starch, barium ferrite and carbon black) was investigated using a drop weight impact machine. The aim of this study was to characterize and assess the effects of fiber orientation at various angles and filler mixtures into epoxy matrix on the impact response. All the tests were carried out at constant impact energy, namely 90.629 J. Results indicated that the fiber orientation at various angles has a positive effect on impact response, mainly in the case of aramid fabric reinforced composites. In terms of influence of fillers addition into matrix, it was obtained an improvement on the impact response of hybrid fabric reinforced composite as compared to the pure fabric reinforced composites.

     

(Al2O3)f/Al复合材料在强界面结合下的疲劳损伤模式

在拉-拉载荷下测定了(Al₂O₃)_f/Al复合材料的疲劳寿命(S-N)曲线。通过夭折试验以及SEM疲劳断口和纵截面组织结构分析,研究了复合材料的疲劳损伤模式。研究结果表明,(Al₂O₃)_f/Al复合材料的疲劳极限为750MPa,远高于SCS-6碳化硅纤维增强钛基复合材料。该复合材料兼有钛基和树脂基纤维复合材料疲劳损伤的特点,高应力下由单个裂纹的起源和生长导致复合材料的失效;低应力下,疲劳损伤模式包括纤维劈裂、众多基体裂纹和单个基体裂纹的横向扩展。其中纤维劈裂是主控机制。其更高的疲劳极限可归因于低应力下纤维的纵向劈裂。     

Influence of the P/M process on the microstructure and properties of WC reinforced copper matrix composite

The influence of powder metallurgy pressing procedure on 9%WC reinforced copper matrix composite was investigated, and the fracture surfaces of the composite in different states of process were observed by scanning electron microscope. The mechanism of fracture of the composite was analyzed. The results show that the pressing process apparently influences the properties and microstructure of the composite. The properties improved with processing sequence progression and the microstructure in terms of the distribution of WC particles in the composite became more uniform. The pressing process can improve the bonding at the interface between copper and WC particles and increases the critical stress for crack extension.     

碳纤维含量对短碳纤维－铜复合材料性能的影响

用粉末冶金法制造了碳纤维分布均匀的碳纤维一铜复合材料，测定了复合材料的力学性能和物理性能，表明在碳纤维与铜基体之间存在界面结合，碳纤维含量对复合材料性能影响极大。