Preparation Of Foils Research Articles

Dual‐Phase Enabled Sinusoidal Current Anodizing for Efficient Preparation of High Specific Capacitance Anode Aluminum Foils

The anodized aluminum oxide prepared by anodizing is the core of aluminum electrolytic capacitors, and its quality determines the performance of aluminum electrolytic capacitors. The traditional direct current (t‐DC) anodizing method commonly used in industrial production today with low current density has the problems of low anodizing efficiency, poor crystallinity, and high formation constants of the oxide film. However, high current density direct current anodizing has the problems of severe defects of the oxide film and much thermal dissolution of aluminum foil. Herein, the dual‐phase enabled sinusoidal current (DESC) anodizing method is proposed for the preparation of 200 V anodized aluminum foil with much higher efficiency and performance. After testing, it is found that the alumina prepared by the DESC method has higher crystallinity and fewer defects. Consequently, the specific capacitance of the DESC sample is 23% greater than that of the t‐DC anodized sample, while the former displays a lower loss angle tangent and leakage current. Meanwhile, DESC anodizing takes 60% time less than t‐DC anodizing due to its high current density. The DESC anodizing method has been identified as a promising avenue for further investigation, exhibiting high efficiency and performance.

The Preparation of Thin Conductive Polyimide Foils for Nuclear Targets.

Thin and conductive plastic foils are of great interest to the target preparation and nuclear physics communities as a backing support for neutron-induced reaction measurements. This paper describes the preparation and characterization of thin, freestanding conductive polyimide films with an areal density suitable for target preparation in nuclear chemistry applications. The films were fabricated by blending a variety of graphene-based nanoparticles, a custom-made graphene suspension, and carbon nanotubes within a polymer matrix. The fabrication of freestanding polyimide films with an areal density of 30 μg/cm2 (∼210 nm) was both time-consuming and difficult. Here, a novel approach is described that employs a sacrificial layer and graphene material to make thin (pure and conductive) polyimide foils readily available within 24 h.

Gelatin Effects on the Kinetic of an Electrodeposition Process in Copper Foil Preparation

Gelatin Effects on the Kinetic of an Electrodeposition Process in Copper Foil Preparation

Prestrain Guided Yield of Large Single-Crystal Nickel Foils with High-Index Facets.

Single-crystal metal foils with high-index facets are currently being investigated owing to their potential application in the epitaxial growth of high-quality van der Waals film materials, electrochemical catalysis, gas sensing, and other fields. However, the controllable synthesis of large single-crystal metal foils with high-index facets remains a great challenge because high-index facets with high surface energy are not preferentially formed thermodynamically and kinetically. Herein, single-crystal nickel foils with a series of high-index facets are efficiently prepared by applying prestrain energy engineering technique, with the largest single-crystal foil exceeding 5×8 cm2 in size. In terms of thermodynamics, the internal mechanism of prestrain regulation on the formation of high-index facets is proposed. Molecular dynamics simulation is utilized to replicate and explain the phenomenon of multiple crystallographic orientations resulting from prestrain regulation. Additionally, large-sized and high-quality graphite films are successfully fabricated on single-crystal Ni(012) foils. Compared to the polycrystalline nickel, the graphite/single-crystal Ni(012) foil composites show more than five-fold increase in thermal conductivity, thereby showing great potential applications in thermal management. This study hence presents a novel approach for the preparation of single-crystal nickel foils with high-index facets, which is beneficial for the epitaxial growth of certain two-dimensionalmaterials.

High-efficiency and low-consumption preparation of ultra-thin and high-performance nanotwinned copper foils by high-gravity intensified direct current electrodeposition

In study, a novel strategy was adopted by the integration of microstructure control and electrodeposition process intensification for high-efficiency, low-consumption and convenient electrodeposition of high performance and ≤4.5 μm ultra-thin copper foils for lithium-ion battery (LIB) collectors. The microstructure and the electrodeposition process of copper foils were effectively controlled and enhanced by the synergy of optimized electrolyte and Multi-Concentric Cylindrical Electrodes-Rotating Bed (MCCE-RB) which was used to generate high-gravity fields. Equiaxed nanotwinned copper (nt-Cu) foils possessed ultra-thin thicknesses ranging from 3.70 to 4.08 μm. They exhibited tensile strength and elongation of 787 MPa and 21.2 %, respectively. In contrast to the conventional direct current electrodeposition, electrodeposition and current efficiency were increased by 15.1 % and 27.2 %, respectively, while the energy consumption was decreased by 23.7 % in the high-gravity field. This is beneficial to improve the weight and energy density of LIBs by applying the strategy and technique of high-gravity intensifying.

Single-crystal Cu(1 1 1) foil preparation by direct bonding technology

Considering the significant advantages of single-crystal Cu(111) in the synthesis of 2D materials and many other fields, its controllable preparation has attracted widespread attention. However, the formation of a single-crystal Cu foil has always been hindered by competition among grains with different orientations. Herein, single-crystal Cu(111) was prepared on the basis of the traditional direct bonding copper method. Cu foil and c-plane sapphire substrate were bonded through Cu2O at high temperature. After the reduction of Cu2O by H2, the surface crystal structure of sapphire will guide Cu to form single-crystal Cu(111). The single-crystallinity of Cu(111) and the specific orientation relationship between Cu(111) and sapphire were confirmed by LEED and XRD. Furthermore, the growth of high-quality single-crystal graphene was performed on single-crystal Cu(111). This work not only facilitates the mass production of 2D materials such as single-crystal graphene, but also provides greater application potential to the direct bonding copper technology and single-crystal Cu.

Preparation and properties of copper-aluminum composite strips and foils by horizontal continuous composite casting and rolling

Cu-Al composite strips and foils show broad application prospects in electric power, new energy and other fields. However, they are difficult to prepare because of brittle interfacial intermetallic compounds and deformation ability difference between two matrix metals. In this study, Cu-Al composite strips and foils with the thickness of 350 µm and 50 µm are successfully prepared by horizontal continuous composite casting and rolling. Moreover, the effects of as-cast interfacial layer thickness on the properties of Cu-Al composite strips are studied. In the rolling, the as-cast interfacial layer is broken into fragments, so as to promote the Cu-Al matrix bonding at atomic scale. The local solid-state amorphous transformation is also observed at the newly formed Cu-Al interface. Therefore, with the as-cast interfacial layer thickness decreasing from 400 µm to 25 µm, the peeling strength of Cu-Al composite strips increasing from 15.1 N/mm to 17.5 N/mm. With the as-cast interfacial layer thickness decreasing from 400 µm to 65 µm, the conductivity of Cu-Al composite strips increases from 62.36%IACS to 72.58%IACS because the size of interfacial layer fragments is reduced. However, with the as-cast interfacial layer thickness decreasing from 65 µm to 25 µm, the conductivity decreases from 72.58%IACS to 68.65%IACS because the copper layer thickness after rolling is reduced. Large interfacial layer fragments hinder current conduction, but a suitable interfacial layer thickness can inhibit the coordinated deformation of Cu and Al, so as to increase the proportion of copper layer thickness in the entire composite strip.

Effect of deformation and annealing process on microstructure and properties of Inconel 718 foil

In this study, the Inconel 718 foil with a thickness of 0.05 mm and an average grain size of 1.78 ⁓ 2.68 μm was prepared by multi-pass rolling and annealing. In the annealing process after rolling, two kinds of multistage heat treatments were designed to improve the plasticity and strength of the foil respectively by regulating precipitation phase. The RT process for plasticity enhancement (900 °C × 4 h + 960 °C × 1 h) provides a better elongation of 12.8% and a tensile strength of 1305 MPa. The sufficient pre-precipitation of the fine δ phase promotes nucleation and growth of recrystallized grain to refine the equiaxed grains and improve the strength of the alloy. Fine grains inhibit crack initiation and delay crack propagation to improve the toughness of the foil. Furthermore, the dispersed δ phase balances the stress at the grain boundaries and within the grain, resulting in uniform deformation of the grains to enhance the plasticity of the foil. Based on RT process, strength enhancement process (RT + DA process, RT process +720 °C × 8 h + 620 °C × 8 h) increases the tensile strength of the foil to 1480 MPa and reaches a suitable elongation of 8.52%. The improved tensile strength indicates a significant contribution of intensive γ” precipitation to impede the movement of dislocations. This paper is anticipated to provide as a reference for foil preparation regarding microstructure and property adjustment.

Defect microstructure of a Ti64 alloy under TI2+ ion irradiation. Influence of dose and temperature

The present paper focuses on the microstructural changes in Ti64 alloy after irradiation. The titanium alloys allow a significant decrease in activation and mass with a similar mechanical strength and a similar corrosion resistance than 304 stainless steels, widely used for core internal structures of Pressurized Water Reactors. The use of titanium alloys could be therefore a significant improvement for reactor exploitation and decommissioning. The nature, size and density of the radiation-induced defects are likely to be important parameters governing the in-reactor behavior of the material. The aim of the study was to devise new achievements in thin foil preparation and Transmission Electron Microscopy (TEM) imaging in order to accurately identify and quantify the Ti64 irradiation defects, at temperatures representative of irradiation temperatures in a reactor. The method to image and count the precipitates was developed with samples irradiated by ions at the temperature of 600 °C. Indeed, the microstructure of the sample irradiated at 600 °C was characterized by a low density of tangled dislocations, and big precipitates, that were easily evidenced. Then the process was applied in samples irradiated with ions at 430 °C and 300 °C characterized by a microstructure of tangled dislocations, loops and small precipitates. In 430 °C irradiation condition, the measurement in dark field with a B∼[11–23]α orientation and with a high magnification micrograph provided similar results than Atom Probe Tomography (APT) analyses. In irradiation condition at 300 °C, the precipitates were imaged by TEM as soon as the dose of 1 dpa. However they were not observed at the dose of 0.4 dpa. The precipitates were so small and their density was so high that the measurement by TEM was very imprecise and APT analyses were needed. The results of this microstructural analysis allowed a discussion on the nucleation mechanism of the irradiation defects in Ti64 alloy.

Preparation of meter-scale Cu foils with decimeter grains and the use for the synthesis of graphene films

Chemical vapor deposition (CVD) is the most promising method for the preparation of high-quality and large-area graphene films, especially the epitaxial growth of graphene on large-area single-crystal Cu foils. While single-crystal Cu foils are normally achieved by thermally annealing the commercial polycrystalline Cu foils, their size and therefore the size of graphene films grown on them are limited to the size of the reaction chamber. We report a simple and feasible method to prepare large-area Cu foils with decimeter grains by thermally annealing the rolled-up Cu foils, where the Cu layers are separated by thin porous carbon fiber cloths. The carbon fiber cloths prevent Cu layers from sticking to each other at high temperatures while do not block the gas transportation. In such a way, the utilization efficiency of the reaction chamber is significantly improved, e.g., 0.2 m × (1–2) m Cu foils can be processed even in a 5 cm diameter quartz tube chamber. High-quality graphene films grown on such Cu foils are then demonstrated. This method may be suitable for the annealing of other metal foils to enlarge grain size and the synthesis of other two-dimensional materials on them such as h-BN.

Preparing ultra-thin copper foil as current collector for improving the LIBs performances with reduced carbon footprint

Adopting ultra-thin copper foil as the current collector is one of the most important strategies for improving the gravimetric energy density of lithium-ion batteries (LIBs), however, stumbled by the quality-control of physicochemical properties for ultra-thin foils. Herein, by utilizing combinative additives, the ≤ 4.5 µm ultra-thin electrolytic copper foil with appealing physicochemical properties is prepared, presenting very low Rz (surface roughness) of 1.74 µm and extraordinarily high tensile strength of 435.65 MPa. When being used as the current collector in LIBs, a high gravimetric energy density of 323.19 Wh/kg was achieved, outperforming both the commercial 9 µm candidate (205.81 Wh/kg) and the purchased 4.5 µm counterpart (310.48 Wh/kg). Also, decreasing the thickness of commercial copper foil (9 µm) to 4.5 µm demonstrates superiorities in both resources saving and environmental benignity, contributing to ∼32 million tons copper savings in 2030 and 40.6 % elimination in carbon footprint for copper foil preparation. The results herein can provide guidance for quality-controlled preparation of ultra-thin copper foil as well as new insights for resource savings and environmentally friendly manufacturing.

Preparation of different carbon stripper foils and application in beam diagnostics

The production of carbon stripper foils that are mounted at different locations of the heavy-ion accelerator is an important task of the target laboratory, and the process for the preparation of carbon foils is constantly improved. Recently, we tested additional heat treatment of the carbon stripping foils following our standard procedure to reduce stress in the foils, since the performance and the durability of these stripping foils is a crucial factor for effective operation. We investigated the properties of foils produced some time ago and of foils freshly produced with the standard procedure, and foils treated thermally after the standard procedure. For the beam diagnostic department at GSI radiation resistant target materials for transverse ion beam profile measurement is an ongoing research topic. In that framework, the feasibility of Optical Transition Radiation (OTR) generation due to ion beam interaction with metal target for beam profile determination has been investigated. Here, carbon stripper foils are applied to enhance the OTR signal. The differently prepared foils were applied in many different experiments of the beam diagnostic department. We describe the performance of the foils during irradiation and compare the features of foils before and after irradiation.

Hematite Exsolutions in Corundum from Cenozoic Basalts in Changle, Shandong Province, China: Crystallographic Orientation Relationships and Interface Characters

Here, we present well-oriented hematite exsolutions in corundum megacrysts from Cenozoic basalt in China. Crystallographic orientation relationships (CORs) and the interface characters between the hematite exsolutions and the corundum host were analyzed by electron backscatter diffraction (EBSD) and high-resolution transmission electron microscope (HRTEM), respectively. The CORs and the regular interface confirm the exsolution and the exsolution was formed under depressurization based on the crystal chemistry theory. There are three groups of exsolutions intersected with ~60°. Two groups of the exsolutions have the same orientation with the host and the other group is twinned to those two groups. Focused ion beam (FIB) for HRTEM foil preparation was carried out. HRTEM photographs show that there are periodic coherency units at (0001) interface. The measured unit lengths are 6.71–6.72 nm, which are in good agreement with every 17-DCrn011¯2projection or 16-DHem011¯2projection. Based on the results, the possibility is that at the interface, the hematite-corundum phases tend to modulate to achieve the maximum coherency in the geological process during exsolution. This research is helpful to understand the interface characters between the exsolution and host.

Preparation and Properties of Cu-Al Bimetallic Strips and Foils by Horizontal Continuous Composite Casting and Rolling

Preparation and Properties of Cu-Al Bimetallic Strips and Foils by Horizontal Continuous Composite Casting and Rolling

The Effect of Ethanol on Abnormal Grain Growth in Copper Foils.

Single-crystal Cu not only has high electrical and thermal conductivity, but can also be used as a promising platform for the epitaxial growth of two-dimensional materials. Preparing large-area single-crystal Cu foils from polycrystalline foils has emerged as the most promising technique in terms of its simplicity and effectiveness. However, the studies on transforming polycrystalline foil into large-area single-crystal foil mainly focus on the influence of annealing temperature and strain energy on the recrystallization process of copper foil, while studies on the effect of annealing atmosphere on abnormal grain growth behavior are relatively rare. It is necessary to carry out more studies on the effect of annealing atmosphere on grain growth behavior to understand the recrystallization mechanism of metal. Here, we found that introduction of ethanol in pure argon annealing atmosphere will cause the abnormal grain growth of copper foil. Moreover, the number of abnormally grown grains can be controlled by the concentration of ethanol in the annealing atmosphere. Using this technology, the number of abnormally grown grains on the copper foil can be controlled to single one. This abnormally grown grain will grow rapidly to decimeter-size by consuming the surrounding small grains. This work provides a new perspective for the understanding of the recrystallization of metals, and a new method for the preparation of large-area single-crystal copper foils.

Scalable Preparation of Ultrathin Graphene-Reinforced Copper Composite Foils with High Mechanical Properties and Excellent Heat Dissipation.

As an important basic material of electronic equipment, copper (Cu) foils should have a small thickness, good mechanical properties, and excellent thermal conductivity. However, preparing an ultrathin Cu foil with good properties remains challenging. Herein, we report an electroless deposition (ELD) strategy for the facile and scalable preparation of an ultrathin freestanding nickel-coated graphene (NCG)/Cu composite foil in a short time of 25 min. The NCG can significantly improve the mechanical and physical properties of composite foils. Experimental results reveal that the NCG/Cu composite foil manifests the best performance when the NCG concentration in an ELD bath was 30 mg/L. The composite foil evidenced a thickness of 1.1 μm, a high tensile strength of 338.7 MPa, and a high thermal conductivity of 431.2 W/mK. Compared with the pure Cu foil, both bending times and elastic modulus are increased by 298.1 and 737.3%, respectively. Remarkably, the composite foil has excellent heat dissipation performance, showing enormous potential as a heat sink material. This work proposes a new method for manufacturing the ultrathin graphene-reinforced Cu composite foil with high performance for numerous applications.

Fast growth of centimeter-scale single-crystal copper foils with high-index planes by the edge-incision effect

Single-crystal copper substrates have gained importance for the preparation of high-quality graphene and hexagonal boron nitride monolayer films by chemical vapor deposition (CVD). Especially, large-scale single-crystal copper foils with high-index planes are synthesized recently and attract great interests. However, the current synthesis methods of single-crystal copper foils and films are energy and time-consuming. Here, we show a rapid and efficient approach for the preparation of centimeter-scale single-crystal copper foils by making small incisions at the edges of polycrystalline copper foils before high-temperature annealing. 1.5 cm × 4 cm pieces of grain-boundary-free copper foils can be prepared by annealing at 1080 °C for 60 min. The annealed copper foil manifests a single high-index plane and is grain-boundary-free over the whole area. We also show that CVD of graphene on the high-index single-crystal copper affords a higher growth rate than on low-index copper substrates.

A Novel Stacked Generalization Ensemble-Based Hybrid PSVM-PMLP-MLR Model for Energy Consumption Prediction of Copper Foil Electrolytic Preparation

At present, the energy consuming during the electrolytic copper foil preparation accounts for more than 75% of the total energy consumption. In real-life production, the process parameters are set by the operator empirically and the system may not work at the operating point with minimum energy consumption. Therefore, it is critical to establish an effective model for predicting electrolysis energy consumption to guide the parameters design. In this paper, a novel hybrid model (named PSVM-PMLP-MLR) based on stacked ensemble learning is proposed. The model is divided into two parts: the base-learning model and the meta-learning model. The support vector machine (SVM) model and multilayer perceptron (MLP) model with different input structures are established by the former first. Then the particle swarm algorithm is employed to determine the optimal value of SVM parameters and the optimal weight of MLP by minimizing the mean absolute percentage error (MAPE). The multiple linear regression (MLR) is finally employed as a meta-learning machine to compute the final predictions. Experimental results show that the regression coefficient of this model reached 0.987, and compared with the traditional SVM and MLP models, the accuracy of the model is improved by 10.29% and 8.28%, respectively.

Electrochemical Signatures of Interface-Dominated Behavior in the Testing of Calcium Foil Anodes

Fundamental research and practical assembly of rechargeable calcium (Ca) batteries will benefit from an ability to use Ca foil anodes. Given that Ca electrochemistry is considered a surface-film-controlled process, understanding the interface’s role is paramount. This study examines electrochemical signatures of several Ca interfaces in a benchmark electrolyte, Ca(BH4)2/tetrahydrofuran (THF). Preparation methodologies of Ca foils are presented, along with Ca plating/stripping through either pre-existing, native calcium hydride (CaH2), or pre-formed calcium fluoride (CaF2) interfaces. In contrast to earlier work examining Ca foil in other electrolytes, Ca foils are accessible for reversible electrochemistry in Ca(BH4)2/THF. However, the first cyclic voltammetry (CV) cycle reflects persistent, history-dependent behavior from prior handling, which manifests as characteristic interface-derived features. This behavior diminishes as Ca is cycled, though formation of a native interface can return the CV to interface-dominated behavior. CaF2 modification enhances such interface-dominance; however, continued cycling suppresses such features, collectively indicating the dynamic nature of certain Ca interfaces. Cell configuration is also found to significantly influence electrochemistry. With appropriate preparation of Ca foils, the signature of interface-dominated behavior is still present during the first cycle in coin cells, but higher current density compared to three-electrode cells along with moderate cycle life are readily achievable.

Reversibility of the β ↔ α Phase Transformations as the Key Factor Determining Whether the Pd–Cu Membrane Foil Texture Depends on the Foil Preparation Process

We have studied the phase composition and texture of a Pd–Cu solid solution with a nearly equiatomic composition in different steps of the preparation of membrane foil by rolling to 300, 175, 100, and 20 μm and 7-μm-thick foil produced by magnetron sputtering of a target having the same composition as the foil. We have identified orientation relationships between the β- and α-phases in the as-prepared two-phase structures and demonstrated that, after heating to 600°C and subsequent cooling, the ordered solid solutions (β-phase) prepared by the two processes, have identical textures, which can be understood in terms of the transformation mechanism.