Papers by Keyword: Copper

Abstract: The demand for flexible and wearable electrochemical sensors has surged due to their low cost and portability. This study produces and characterizes low-cost and environmentally friendly flexible laser engraved graphene/Cu nanoparticles composite materials as a potential electrode for electronic applications. The electrode is fabricated by directly engraving Polyimide substrate using a CO₂ laser machine to produce Laser Engraved Graphene (LEG). The electrode is then modified with copper nanoparticles via a one-step pulse electrodeposition technique to be characterized structurally, mechanically, and electrochemically using SEM, XRD, bending test, electrochemical impedance spectroscopy, and cyclic voltammetry to assess their stability and electrocatalytic activity. The laser irradiation of PI results in 3D porous graphene structure formation that increases electron transfer rate and the electrochemically active surface area. Copper deposition improves the sensitivity of LEG by its high conductivity.

Abstract: The economical and highly productive method of welding is used to join a dissimilar material. The quality of welded joint with high efficiency is obtained from friction welding process. The intention of the current work is to assess the progress of solid state juncture of dissimilar materials of aluminum 6082 and copper. The strong joints were developed using frictional heat and external pressure. The friction welded joints were tested under welding strength and surface analysis using scanning force microscopy (SFM). Rotational speed, friction pressure and forging pressure were used to evaluate the performance of the welded joints. Optimize the welding strength and hardness was attained through taguchi method.

Abstract: This paper is dedicated to the investigation of selective copper extraction from the black mass of lithium-ion batteries (LIBs) using ammonium sulfate. Thermodynamic analysis performed with the use of Pourbaix diagrams allowed to compare and predict the area of stable copper and cobalt ammine complexes, determine operating pH range (8.7-9.7) for solutions. Concentrations of sodium hydroxide and ammonium sulfate were defined experimentally allowing to achieve high copper extraction (82-87 %) at low cobalt recovery into solutions (0.25-0.52 %). By variation of main leaching parameters optimal process conditions were determined: (NH₄)₂SO₄ 45 g/dm³, NaOH 9 g/dm³, 25 С, l : s = 5 : 1, 120 minutes.

Abstract: This paper discusses Copper Metal Matrix Composites. It is obvious that copper matrix composites have been heavily relied upon by many industries because of their high wear resistance, corrosion resistance, excellent electrocatalytic properties, and high strength. The excellent electrical conductivity of copper-based materials also enables these materials to function as lubricants and anti-frictional materials. These materials were widely used in transportation, electrical contact transmission, and aerospace. Copper-based metal matrix composites have wide application due to their excellent mechanical, electrical, and thermal characteristics. Copper based metal matrix composites are also corrosion resistant and have a high strength. A contemporary study evaluated the effects of different parameters on powder metallurgy fabricated copper matrix metal composites. The focus was on understanding the applications and mechanical properties of copper-based composite materials.

Abstract: During cold wire drawing process, the drawing stress applied to the wire at the exit of the die must be lower than the material yield stress (including strain-hardening) to avoid wire necking and fracture. Several studies have been developed to investigate and model the stress acting on the wire in the single pass drawing and its dependence on the main process parameters. The aim of this work is to apply an analytical model for the calculation of the drawing stresses during the whole complex multi-pass manufacturing process in industrial environment, considering not only the forces acting in the die but also the driving forces of the rotating capstans (drawing tension and back tension). The drawing of ETP Pure Copper (99.9% in weight), using two industrial multi-pass machines with different reduction ratio sequences, is analysed and then discussed in order to understand the different failure rates. Finally, the study compared step by step, the evolution of the drawing stresses respect to material yield stress when different processing conditions (i.e. change of capstan windings, change of friction conditions in the die and in the capstan) are applied.

Abstract: The present study investigates the tensile behavior of the two bimetallic composite wires Cu-Al and Fe-Al. The purpose is to understand the deviation their tensile strengths show from the Rule of Mixtures’ prediction. To that end, an experimental-numerical approach was adopted. Following tensile testing of the above cold-drawn composite wires, the manufacturing process (wire drawing) was simulated via finite element analysis. The prominent role of processing-induced residual stresses on the yield strength of cold-drawn products is known. Therefore, a discussion based on the axial tensile residual stress profile was developed. It was concluded that the higher-magnitude-near-surface tensile residual stresses in the Fe-Al wire causes its tensile curve to show a negative deviation from the Rule of Mixtures (RoM). The Cu-Al wire, on the contrary, exhibits a slight positive deviation.

Abstract: The impact of COVID-19 crisis on global supply chains caused a critical shortage of essential goods like medical devices. Additionally, massive consumption increased mask contamination and waste. 3D printing has become a fast and versatile manufacturing alternative that prevents a single use of masks. However, SARS-CoV-2 virus can persist on plastic surfaces for days. This study proposes the optimization of 3D printed masks, by applying a coating rich in hydrolyzable tannins and copper, in order to diminish the virus presence. Different paints were formulated with copper tannate and applied on thermoplastic polyurethane 3D panels to test bacterial stability. Results showed a significant reduction of colony-forming units on coated polymeric surfaces. Paints pigmented with copper tannates could improve the protection provided by printed masks, even against the COVID-19 virus.

Abstract: Copper (Cu) was deposited on two different types of zinc oxide (ZnO), namely commercial ZnO (CZ) and mesoporous zinc oxide (MZ), using a simple electrolysis technique. The catalysts were characterized by XRD, FTIR, BET and UV-Vis DRS. The synergistic effect between Cu, CZ and MZ was tested in the degradation of 2,4-dichlorophenol (2,4-DCP) under visible light irradiation. Cu-MZ exhibited the best performance with 97% degradation compared to MZ, Cu-CZ, CZ and CuO with 80%, 70%, 55% and 49%, respectively. The introduction of Cu in CZ and MZ was found to decrease the band gap energy of ZnO from 3.20 to 3.05 eV and 2.90 to 2.60 eV, respectively. The role of Cu in reducing the band gap energy of Cu-CZ and Cu-MZ probably contributed significantly to the good photocatalytic degradation of 2,4-DCP.

Abstract: Adsorption is a unit operation of separating solute from solution using another solid material. Modelling of experimental adsorption isotherm data is an essential way for predicting the mechanisms of adsorption, which will lead to an improvement in adsorption science. The main aim of the present work is to analyse various forms of Langmuir isotherm for adsorption of copper from its aqueous solution using cucumber peel from the batch experimental data. The linearized and nonlinearized isotherm models were compared and discussed. In order to determine the best fit isotherm model, the determination coefficient (R²) and sum of square of error (SSE) for each model were used. The modelling results showed that nonlinear Langmuir model could fit the data better than other forms, with relatively higher R² values (0.9879) and smaller SSE (0.013). The linear forms of Langmuir model had the maximum adsorption capacities deviated from the experimental data. The maximum adsorption achieved was 66.61 mg/g after validation with experimental results.

Abstract: The (Zn_0.5Cu_0.5)Al₂O₄ pigments were synthesized by solid state processing with an aim to examine the kinetics of phase formation. The calcining temperature was 1100 °C with firing times of 2, 12, 24, 48 and 96 hours during which intermediate grinding was carried out. All five obtained pigment samples appeared to be single-phase as probed by XRD. However, lattice refinement revealed differences in the lattice constant which kept decreasing and reached constancy after 24 hours of firing. Such reduction in the lattice constant was associated with incorporation of smaller copper cations into the Zn-sites. FTIR spectra also supported this result as the relevant peaks still got broadened and shifted for the calcination times of less than 48 hours. Elemental analysis of the 2-hour sample showed small presence of starting precursor particles, though not detected by XRD, suggesting an incomplete reactivity at a minute scale. These structural changes were resultantly reflected by small but significant alterations in the color parameters. A higher degree of solid solution for the samples fired for longer times, as judged by lowering in the lattice constant, resulted in detectable changes in both a and b parameters. Longer calcination times yielded a brighter (higher L values) brownish tone likely due to both diminution in the averaged particle size from pulverizing and completion of solid solution. The first would be useful for good dispersion in glazes whereas the latter could be directly related to the degree of cationic substitution, confirming the expected “true” color for this specific doping level at a particular calcination temperature.