Highly (111) Textured Copper Foils with High Hardness and High Electrical Conductivity by Pulse Reverse Electrodeposition
TL;DR: In this article, the pulse reverse electrodeposition of highly textured freestanding copper foils, in an additive-free electrolyte, exhibiting hardness as high as 2.2-2.7 GPa with an electrical conductivity equal to that of bulk copper, was reported.
Abstract: The present article reports the pulse reverse electrodeposition of highly (111) textured freestanding copper foils, in an additive-free electrolyte, exhibiting hardness as high as 2.2―2.7 GPa with an electrical conductivity equal to that of bulk copper. The short anodic pulse applied and the absence of organic additives allowed the formation of highly dense foils with room-temperature stability in terms of mechanical and electrical properties. The process involves a fast electrodeposition method with a deposition rate of 25―50 μm/h. The (111) texture and twin boundaries contribute to the high hardness and better electrical conductivity of the copper foils.
Citations
More filters
TL;DR: Annealing of these nanocomposite foils at 300°C, neither causes grain growth of the Cu matrix nor deteriorates the mechanical properties, indicating the role of graphene as an excellent reinforcement material as well as a grain growth inhibitor.
Abstract: Graphene has proved its significant role as a reinforcement material in improving the strength of polymers as well as metal matrix composites due to its excellent mechanical properties. In addition, graphene is also shown to block dislocation motion in a nanolayered metal-graphene composites resulting in ultra high strength. In the present paper, we demonstrate the synthesis of very hard Cu-Graphene composite foils by a simple, scalable and economical pulse reverse electrodeposition method with a well designed pulse profile. Optimization of pulse parameters and current density resulted in composite foils with well dispersed graphene, exhibiting a high hardness of ~2.5 GPa and an increased elastic modulus of ~137 GPa while exhibiting an electrical conductivity comparable to that of pure Cu. The pulse parameters are designed in such a way to have finer grain size of Cu matrix as well as uniform dispersion of graphene throughout the matrix, contributing to high hardness and modulus. Annealing of these nanocomposite foils at 300°C, neither causes grain growth of the Cu matrix nor deteriorates the mechanical properties, indicating the role of graphene as an excellent reinforcement material as well as a grain growth inhibitor.
208 citations
TL;DR: In this paper, the elastic moduli of six commercial copper current collector (CCC) foils were measured using three techniques: a standard microtensile testing machine equipped with a laser sensor, dynamic mechanical analysis (DMA), and nanoindentation.
Abstract: The functionality and reliability of the current collector (CC) are crucial to design and fabricate electrodes for Li-ion batteries because the CC serves as the bridge between external electronic and internal Li-ion transports. Therefore, understanding the mechanical behavior of CCs is of great importance for battery design and manufacturing. In this paper, we report the measured values of the elastic moduli of six commercial copper current-collector (CCC) foils. Measurements were performed using three techniques: a standard microtensile testing machine equipped with a laser sensor, dynamic mechanical analysis (DMA), and nanoindentation. For electrolytic copper (E-Cu) foils, we find elastic moduli of approximately 70 GPa, and for rolled copper (R-Cu) foils, we find elastic moduli of approximately 50 GPa. Values for yield strength and fracture strength of the foils were determined from load-deflection curves; the results are consistent with values recommended by the manufacturer. Crystalline structures, which influence values for the elastic moduli of the foils, were investigated by X-ray diffraction. Surface morphologies of the foils before testing and the fracture morphologies after testing were studied by scanning electron microscopy.
38 citations
TL;DR: In this paper, the texture evolution in copper foils prepared by a rapid pulse reverse electrodeposition (PRED) technique using an additive-free electrolyte and the subsequent correlation with the mechanical and electrical properties is investigated.
Abstract: The texture evolution in copper foils prepared by a rapid pulse reverse electrodeposition (PRED) technique using an “additive-free” electrolyte and the subsequent correlation with the mechanical and electrical properties is investigated in this study. Control over (111), (100), and (101) crystallographic textures in copper foils has been achieved by optimization of the pulse parameters and current density. A hardness as high as 2.0–2.7 GPa, while the electrical conductivity was maintained in the same range as that of bulk copper, was exhibited by these foils. A complete study of controlling the (111), (100), and (101) textures, CSL Σ3 coherent twin boundaries, grain refinement, and their effect on the mechanical and electrical properties is performed in detail by characterizing the foils with electron backscatter diffraction, X-ray diffraction, nanoindentation, and electrical resistivity measurements. The PRED technique with short and high-energy pulses allowed the (111) texture with increase in forward o...
36 citations
TL;DR: In this paper, the structural and tribological behavior of pure Ni coating and Ni-WSe2 composite coatings at different WSe2 loading level (0, 0.5, 1 and 2) was investigated.
Abstract: The present work investigates correlation between the structural and tribological behavior of pure Ni coating and Ni-WSe2 composite coatings at different WSe2 loading level (0, 0.1, 0.2, 0.5, 1 and 2 g/l). The developed coatings were characterized by X-ray diffraction technique (XRD), field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) for phase, structure and compositional verifications, respectively. Structural and phase evolution of the coatings were correlated with roughness, microhardness and wear behavior. Characterization confirmed that beyond 0.5 g/l WSe2 content in the electrolyte, the composite coatings turned brittle and non-uniform with high surface roughness. The maximum hardness of 665 HV was observed in case of Ni-0.5 g/l WSe2 coating, whereas, the lowest average coefficient of friction of 0.068 was found in Ni-1 g/l WSe2 followed by 0.07 for Ni-0.5 g/l WSe2 coating. It was observed that Ni-0.5 g/l WSe2 coating possessed optimum mechanical properties and wear resistance.
23 citations
References
More filters
TL;DR: Pure copper samples with a high density of nanoscale growth twins are synthesized and show a tensile strength about 10 times higher than that of conventional coarse-grained copper, while retaining an electrical conductivity comparable to that of pure copper.
Abstract: Methods used to strengthen metals generally also cause a pronounced decrease in electrical conductivity, so that a tradeoff must be made between conductivity and mechanical strength. We synthesized pure copper samples with a high density of nanoscale growth twins. They showed a tensile strength about 10 times higher than that of conventional coarse-grained copper, while retaining an electrical conductivity comparable to that of pure copper. The ultrahigh strength originates from the effective blockage of dislocation motion by numerous coherent twin boundaries that possess an extremely low electrical resistivity, which is not the case for other types of grain boundaries.
2,584 citations
TL;DR: In this paper, a superimposed dislocation network is proposed for the cubic system, which is a natural extension of previous dislocation models and models based on coincidence relationships, and explains many of the observed properties of grain boundaries.
Abstract: A coincidence model of high-angle grain boundaries can be extended to include deviations from coincidence. The generalised boundary has a terraced structure, corresponding to the densely packed planes in the coincidence lattice, and a superimposed dislocation network, corresponding to a sub-boundary in the coincidence lattice. This model is a natural extension of previous dislocation models and models based on coincidence relationships. The model explains many of the observed properties of grain boundaries and should have wide validity for the cubic system.
1,665 citations
TL;DR: A review on pulse and pulse reverse techniques for electrodeposition has been attempted as mentioned in this paper, where the effects of mass, transport, electrical double layer pulse parameters and current distribution on surface roughness and morphology are presented.
Abstract: A review on pulse and pulse reverse techniques for electrodeposition have been attempted. Pulse electrodeposition (PED) of some metals and alloys are reported. The effects of mass, transport, electrical double layer pulse parameters and current distribution on surface roughness and morphology are presented. Applications, advantages and disadvantages of PC and PRC techniques are discussed along with theoretical aspects and mechanism.
731 citations
TL;DR: In this article, the authors investigated the rate sensitivity of flow stress and the extent of strengthening in polycrystalline copper containing different volume fractions of nano-sized twins, but having the same average grain size.
Abstract: We have investigated the rate sensitivity of flow stress and the extent of strengthening in polycrystalline copper containing different volume fractions of nano-sized twins, but having the same average grain size. The specimens were produced by pulsed electrodeposition, wherein the concentration of twins was varied systematically by varying the processing parameters. Depth-sensing instrumented indentation experiments performed at loading rates spanning three orders of magnitude on specimens with the higher density of twins (twin lamellae width � 20 nm) revealed an up to sevenfold increase in rate-sensitivity of hardness compared to an essentially twin-free pure Cu of the same grain size. A reduction in twin density for the same grain size (with twin lamellae width � 90 nm) also resulted in a noticeable reduction in rate-sensitivity and hardness. The presence of a high density of nano-scale twins is also seen to impart significant hardness, which is comparable to that achieved in nano-grained Cu. Post-indentation analyses of indented Cu with nano-scale twins in the transmission electron microscope reveal deformation-induced displacement of coherent twin boundaries (CTBs), formation of steps and jogs along CTBs, and blockage of dislocations at CTBs. These processes appear to significantly influence the evolution of thermal activation volume for plastic flow which is some three orders of magnitude smaller than that known for microcrystalline Cu. Transmission electron microscopy also reveals CTBs with a high density of dislocation debris and points to the possibility that displaced CTBs may serve as barriers to dislocation motion and that they may also provide sources for dislocation nucleation, especially near stress concentrations, very much like grain boundaries. Possible consequences of these trends for deformation are explored.
620 citations
TL;DR: In this article, the fundamental concepts of grain boundary engineering (GBE) accompanied by a critical appraisal of GBE investigations are reported, and several variants on processing route schedules to produce successfully a GBE microstructure with improved properties.
Abstract: This overview reports the fundamental concepts of grain boundary engineering (GBE) accompanied by a critical appraisal of GBE investigations. The main conclusions are as follows. There are many variants on processing route schedules to produce successfully a GBE microstructure with improved properties. The role of twinning is indirect and twins have several functions at different stages of the GBE process, which are necessary for the development of microstructure and properties: firstly to retain strain, then to generate non-coherent Σ3s (and other `special' boundaries), and finally to break up the random boundary network. Connectivity of boundary types is more important than the absolute fraction of special boundaries. The `strain recrystallisation' description of GBE processing is in fact a recovery process. Accordingly, strain-recrystallisation and strain-anneal GBE do not involve separate mechanisms. The CSL model has ambiguities with regard to recognition of special boundaries. Finally, near-future challenges for GBE are identified.
559 citations