Electrolytic Copper Powder Research Articles

Spark Plasma Sintering of a Cu-Cu2O powder obtained by partial oxidation of electrolytic copper

Studies of consolidation of pre-oxidized powders are interesting from the viewpoint of gaining an understanding of the features of sintering of metallic core-oxide shell particles and the formation of oxide-reinforced composites. If spark plasma sintering (SPS) is selected as a consolidation method, the possibility of the oxide interacting with graphite tooling/foil should be taken into account in the development of metal-oxide composites. In the present work, materials fabricated by SPS of a partially oxidized copper powder containing Cu2O were studied. The pre-oxidized powder obtained by annealing an electrolytic copper powder in air was subjected to SPS in contact with a graphite foil. Pressureless SPS at 700 °C resulted in the formation of a porous structure, in which the morphology of the ligaments was similar to that of the particles of the oxidized powder. The grain structure of the oxide layers could be well distinguished. After SPS at 700 °C and 40 MPa; the Cu2O phase was preserved even in the subsurface layer of the compact. The oxide reduction to metal was observed after SPS at 900 °C and occurred only in the vicinity of the graphite foil. The Cu-Cu2O composites sintered under a pressure of 40 MPa at 700 °C and 900 °C had a porosity of 5% and a Vickers hardness of 140±5 HV0.3 and 120±5 HV0.3, respectively. A reduction in hardness of the composites can be explained by grain growth in the material sintered at a higher temperature.

On The Potential Use of Copper-Modified Geopolymer Incorporating Lead-Smelter Slag for Thermal Energy Storage

Thermal energy storage (TES) system has been widely employed in concentrated solar power (CSP) plants to ensure the system efficiency. With excellent thermal characteristics, electrolytic copper powder (ECP), graphene oxide (GO) and lead-smelter slag (LSS) aggregate – a mining waste material, have been utilised in this study, aiming to fabricate metallurgical geopolymer material as a storage medium in the TES system. This paper investigated the effect of ECP contents (0, 5%, 10%, 15%, 20%) on the strength, specific heat, thermal conductivity and thermal stability of GO-engineered geopolymer mixes incorporating LSS aggregate. With 10% ECP inclusion, the flow rate and compressive strength improved significantly. Increasing ECP content improved the thermal conductivity but reduce specific heat of geopolymers. The results revealed that ECP was a promising component to be incorporated into geopolymer to enhance its physio-mechanical characteristics and thermal stability. The combination of ECP, GO and LSS to produce geopolymer materials for TES system can provide an eco-friendly solution to the CSP plants and the industry waste recovery.

RETRACTED: Vorotilo et al. Manufacturing of Conductive, Wear-Resistant Nanoreinforced Cu-Ti Alloys Using Partially Oxidized Electrolytic Copper Powder. Nanomaterials 2020, 10, 1261.

The Nanomaterials Editorial Office retracts the article, "Manufacturing of Conductive, Wear-Resistant Nanoreinforced Cu-Ti Alloys Using Partially Oxidized Electrolytic Copper Powder" [...].

Influence of copper salts on the physical and mechanical properties of copper–graphite composite materials

We investigated composite materials based on electrolytic copper powder containing 1 and 5 wt. % powder of colloidal graphite the addition of trace amounts of copper sulfate and acetate. The materials were obtained through double cold pressing in a mold at a pressure of 600 MPa, intermediate sintering (annealing) in hydrogen at a temperature of 870 °C, and final sintering in vacuum at the copper premelting temperature. To analyze the influence of copper salts on the density, porosity, electrical resistivity, and strength of copper–graphite composite materials, we employed X-ray phase analysis, scanning electron microscopy, conducted strength tests in three-point bending, and determined electrical resistivity. We established that higher graphite content results in increased porosity and electrical resistivity of composite materials, along with decreased strength. In the materials containing copper sulfate, copper is reduced from the salt in the form of nanodispersed particles on the surfaces and inside graphite flakes, leading to a decrease in electrical resistivity compared to copper–graphite composites without salt additives. When copper acetate was added to the composite material, copper is reduced from the salt mainly on the surfaces of graphite particles in the form of microdispersed particles and their aggregations, as the copper acetate solution does not wet the graphite. In this case, the electrical resistivity was somewhat higher than that of the composite with sulfate but lower than that of the material without salts. The bending strength of the studied materials decreased as salts were introduced due to increased porosity and emerging defects in the crystal structure of graphite during its intercalation with copper.

EFFECT OF PARTICLE SHAPE AND SIZE OF COPPER POWDERS ON THE PROPERTIES OF SINTERED PARTS

The particle shape and size of the starting powders represent the most important physical properties, on which the quality of the compacts and final sintered products depends. Two types of powder were analyzed in the paper - electrolytic copper powder with a dendritic particle shape and water-atomized copper powder with an irregular particle shape. The starting powders were sieved through a sieve system with openings of 45 μm, 80 μm, and 120 μm. The characterization of the obtained fractions of both powders was performed by determining the shape and dimensions of the particles using SEM microscopy in combination with ImageJ software, and the apparent density and flow rate were determined using the Hall flowmeter funnel. Pressing of each powder fraction was done using a pressure of 600 MPa. The compacts were further sintered at 1000°C for 2 hours to obtain the final sintered parts. After sintering, their density, hardness, and electrical conductivity were determined and their microstructure was analyzed. The results indicate a great influence of the characteristics of the starting powders on the properties of the final parts obtained by the powder metallurgy route. The particle shape of the powders had a more pronounced influence compared to the particle size.

Enhancement of electrical and thermal conductivity of low-cost novel Cu–Ag alloys prepared by hot-pressing and electroless plating from recycled electrolytic copper powders

In this study, electrolytic copper powders (ECs) were fabricated by electrolysis method using scrap copper pieces as the main material. Copper-silver bimetallic powders (ESCs) were obtained by electroless silver coating process. Then, copper-silver layered materials (ESC materials) with different process parameters were fabricated by using the hot-pressing method. The effects of hot-pressing temperature (25, 200, 400, 500 and 550 °C) and pressures (400, 500 and 600 MPa) on the properties of ESC materials were investigated. Morpholological examination of ECs and ESCs and microstructure examination of layered copper-silver materials was performed using scanning electron microscopy (SEM). Electrical and thermal conductivity, hardness and density of the materials produced with different hot-pressing parameters were examined. According to the results, it was determined that materials with the best physical and mechanical properties were obtained when the temperature used in hot- pressing was 500 °C and the pressure was 600 MPa. In materials produced at higher temperatures and pressures, a decrease in electrical and thermal conductivity values was determined as a result of the increase in deformation.

Effect of Halide Ions on Electrodeposition Behavior and Morphology of Electrolytic Copper Powder

Effect of Halide Ions on Electrodeposition Behavior and Morphology of Electrolytic Copper Powder

Production of Spherical Electrolytic Copper Powder from the Solution Containing Polyethyleneimine

Production of Spherical Electrolytic Copper Powder from the Solution Containing Polyethyleneimine

Impact of synergy effect of SDBS and PVP on morphology and performance of electrolytic copper powder

Copper powder is prepared by electrolysis, and additives Sodium dodecyl benzene sulfonate (SDBS) and polyvinyl pyrrolidone (PVP) are added to the electrolyte. Through the synergy effect of the two additives, the shielding effect between metal atoms is enhanced, and as a consequence the microscopic morphology is changed and it the powder performance is improved. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and Electrochemical Impedance Spectroscopy (EIS) are used to characterize the copper powder. The results show that when the content of SDBS and PVP is 5 g l−1 and 1.5g l−1 respectively, the new type of thin and long dendrite copper powder can be obtained by electrolysis.

Fine Copper Powders Production

The article is devoted to the description of a method for producing electrolytic copper powder with an average particle size of 3 to 10 μm. In order to increase the proportion of the finely dispersed fraction during the electrolysis process, the composition of the electrolyte was changed. In particular, the content of chloride ions was increased from 6 to 53 mg/dm3. After the growth of the powder in industrial baths, its subsequent drying and sieving on vibrating screens, samples were obtained with a fraction of 5 μm content in the range from 3 to 38 %. Additionally, air classification of powders was carried out at various speeds of the classifier rotor from 800 to 2000 rpm. Based on the results of the study, the optimal ranges of the specific surface area and the size of the initial powder particles before classification, as well as the composition of the electrolyte and the operating modes of the classifier, were determined.

Effect of Polymer Additives and Chloride Ions on Electrodeposition Behavior and Morphology of Electrolytic Copper Powder

To investigate the effect of polymer additives and chloride ions on the electrodeposition behavior and morphology of copper powder, the polarization curves were measured and constant current electrolysis of 300 A·m−2 and 500 A·m−2 was conducted in an electrolytic solution containing 0.079 mol·dm−3 of Cu2+ and 0.5 mol·dm−3 of free H2SO4 at 293K and 393 K without stirring. Polyethylene glycol (PEG) and polyethyleneimine (PEI) were used as polymer additives. PEG and PEI had a suppressing effect on the electrodeposition of copper powder. The current efficiency for Cu deposition decreased with the addition of PEG and PEI. The addition of PEG decreased the average particle size of the copper powder, while PEI didn’t change the average particle size. When Cl− coexisted with PEG, the suppressing effect on the electrodeposition of copper powder became even greater and the particle size of the copper powder became finer than when Cl− or PEG was added alone.

Effect of Halide Ions on Electrodeposition Behavior and Morphology of Electrolytic Copper Powder

Effect of Halide Ions on Electrodeposition Behavior and Morphology of Electrolytic Copper Powder

Effect of carbon type and morphology on the microstructure and properties of carbon/copper composites

Agglomerated brittle graphite and discontinuous matrix have decreased mechanics and friction properties of natural graphite/copper (NG/Cu) composites prepared through spark plasma sintering (SPS) with the blending of graphite and electrolytic copper powder. In that case, microstructure, mechanics and friction properties of NG/Cu composites were compared with that of carbon particles/cooper (CPs/Cu) composites prepared via ball-milling and SPS. CPs/Cu composites had higher strength and excellent friction properties, due to the uniform distribution of high content CPs (~4 μm, with carbon fiber structure) in Cu matrix, and ~36.40% of low angle grain boundaries (LAGBs) of continuous Cu matrix with finest grain size (~0.90 μm). The effective fixation of CPs by higher strength Cu matrix, combined with the consistency of microregion performance came from high-density uniformly dispersed of the micron-sized CPs, which significantly reduced the friction coefficient of the C/Cu composites against the steel disc and improved the stability of friction performance. Even at 400 °C, the softening of the matrix was greatly weakened owing to the pinning effect of CPs with excellent antioxidant properties on grain boundaries, and CPs/Cu composites still maintain good friction properties.

Manufacturing of Conductive, Wear-Resistant Nanoreinforced Cu-Ti Alloys Using Partially Oxidized Electrolytic Copper Powder.

Reactive powder composites Cu-(0–15%)TiH2 containing up to 5% native Cu2O were manufactured by high energy ball milling and then hot-pressed to produce bulk nanostructured copper–matrix alloys reinforced by Cu3Ti3O inclusions. Two high-energy ball-milling (HEBM) protocols were employed for the fabrication of Cu-Ti alloys: single-stage and two-stage ball milling, resulting in an order of magnitude refinement of TiH2 particles in the reactive mixtures. Single-stage HEBM processing led to the partial retention of Ti in the microstructure of hot-pressed specimens as the α-Ti phase and formation of fine-grained (100–200 nm) copper matrix interspersed with 5–20 nm Cu3Ti3O precipitates, whereas the two-stage HEBM led to the complete conversion of TiH2 into the Cu3Ti3O phase during the hot pressing but produced a coarser copper matrix (1–2 μm) with 0.1–0.2 μm wide polycrystalline Cu3Ti3O layers on the boundaries of Cu grains. The alloy produced using single-stage HEBM was characterized by the highest strength (up to 950 MPa) and electrical conductivity (2.6 × 107 Sm/m) as well as the lowest specific wear rate (1.1 × 10−5 mm3/N/m). The tribological performance of the alloy was enhanced by the formation of Cu3Ti3O microfibers in the wear debris, which reduced the friction coefficient against the Al2O3 counter-body. The potential applications of the developed alloys are briefly discussed.

Differences in mechanical behaviors and characteristics between natural graphite/copper composites and carbon-coated graphite/copper composites

Natural graphite/copper (NG/Cu) composites and carbon-coated graphite/copper (CCG/Cu) composites were prepared via powder metallurgy by using electrolytic copper powder, natural graphite and phenolic resin as raw materials. The mechanical deformation behaviors and characteristics and the structure evolution of the two composites under the actual force form during friction (bending and compression) were investigated in detail. The results show that CCG/Cu composites exhibit ductile fracture and can withstand higher loads in the bending test, which is due to a high compactness and continuity matrix and a uniform distribution of intact CCG, while NG/Cu composites show brittle fracture. Owing to the low compactness and continuity matrix and the incomplete NG structure of NG/Cu composites themselves, the deflection and tear of matrix, the deflection and lamellar layers slide of NG and some NG connection occur from deformation to failure in the compression test, and these structural defects are exacerbated until the main crack penetrates through the sample, leading to failure. Although CCG/Cu composites eventually fail in the compression test, carbon coating with phenolic resin on natural graphite effectively delays the deformation and failure and improves the compression strength of CCG/Cu composites. This work provides a reliable mechanical analysis for the failure mechanism of graphite/copper composites during friction.

A new ammunition for forensic needs: FIOCCHI-RIS

To regulate technical demands for ammunitions used by police forces in Germany, the “Technical Guideline for Cartridge 9 mm × 19, pollution reduced” was introduced in 2001. Beyond standard ballistics performances for cartridges, some specific forensic requirements were added, mainly to allow an efficient detection of gunshot residues (GSR) and a sensitive muzzle-to-target distance determination in shooting cases with police officers involved. Two ammunitions on the market, “ACTION IV Forensis” from RUAG Ammotec and “PEP II/s” from MEN, are known to fulfil the guideline requirements. Recently, a new ammunition for law enforcement use produced by Fiocchi Munizioni, named “FIOCCHI-RIS”, has been put forward for testing compliance with the guideline criteria. The FIOCCHI-RIS primer formulation is a modification of Fiocchi's ZetaPi heavy metal free primer mixture, obtained by adding samarium oxide and titanium oxide to the basic commercial composition made of organic explosives and potassium nitrate. Moreover, electrolytic copper powder is added to the ordinary dibasic spherical gunpowder. Most of the residues, found both in the muzzle blast and inside cartridge cases, are of the SmKSiTiCaAl type, to be considered GSR particles of a highly specific composition, easily detected and classified by energy-dispersive X-ray spectrometry. The Dithiooxamide test has been used as specific chemographic/chromophoric test for the presence of copper on targets, obtaining positive and repeatable results for muzzle-to-target distances up to 150 cm.

Effect of jet flow between electrodes on power consumption and the apparent density of electrolytic copper powders

Electrolysis is one of the main methods for producing copper powder, but has the disadvantage of high power consumption. This paper describes an experimental study of a process for electrolytic production of copper powder in which a jet flow of fresh electrolyte is introduced between anode–cathode pairs. The effects of electrolyte inlet mode and circulation rate on the direct current (DC) power consumption and on the morphology and apparent density of the copper powder produced are investigated. The results show that in the conventional bottom-inlet/top-outlet mode, the electrolyte circulation rate has little influence on DC power consumption. In contrast, when a jet flow is used, an increase in electrolyte circulation rate leads to an increase in current efficiency and a decrease in cell voltage, resulting in a significant reduction in DC power consumption, which drops by as much as 37%. In addition, as a result of agitation by the jet flow, the copper powder deposited at the cathode becomes denser, the powder particles become coarser and less dendritic on the microscale, and their apparent density increases from 0.33 g cm−3 to 1.90 g cm−3.

Influence of porogen type and copper powder morphology on property of sintering copper porous materials

Copper porous materials have been manufactured by the method of powder metallurgy. Electrolytic copper powders and atomized copper powders are used as matrix material. Methylcellulose and paraffin are used as porogen. The influence of porogen type and copper powder morphology on the property of copper porous materials is investigated as well. The results show that copper porous materials with paraffin as porogen have lower porosity and permeability compared with materials using methylcellulose as porogen, due to the different pore-forming mechanisms. The pore forming mechanism of methylcellulose is thermal decomposition, while the pore forming mechanism of paraffin is melting–evaporation. The morphology of copper powders affects the contact state between adjacent powders, which further influence the sintering shrinkage. The porous materials using arborescent copper powders as matrix have lower porosity, smaller pore size and lower permeability, compared with materials with atomized copper powders as matrix.

Effect of Flow Pattern on Energy Consumption and Properties of Copper Powder in the Electrolytic Process

Because of distinctive properties, such as dendritic structure, high green strength, and low oxygen content, electrolytic copper powder has been widely used in aviation, aerospace, national defense industry and other domains. But at present, energy consumption of the electrolysis process in copper powder production is high, and the current efficiency is only about 90%. Therefore,the decrease in energy consumption of the electrolysis process has become the major bottlenecks in the development of the enterprises. In this paper, a new electrolysis cell with different electrolyte inlet arranged on the cell was manufactured. Then, the effect of flow pattern of electrolyte on the current efficiency, energy consumption and properties of copper powder was investigated. The experimental results showed that the electrolytic process had the higher current efficiency, lower energy consumption and smaller copper powders when the flow rate is 0.5l/min in the paralleled inlet and 1.5 l/min in the traditional inlet. Under the optimal conditions, the current efficiency, energy consumption and copper powder size were 99.10%, 712.90kw∙h/t and 47.80um respectively. This means an obvious rise in current efficiency and decrease in energy consumption compared to traditional feeding method.

Naphthalene Diimides Prepared by a Straightforward Method and Their Characterization for Organic Electronics

A new approach for the synthesis of acetylene‐substituted naphthalene diimides in polar solvents with PdCl2, Et3N, and electrolytic copper powder was developed. This simplified approach allows for high‐throughput synthesis, and the reaction products can be readily separated. DFT studies revealed that the electronic structures of these compounds are mainly determined by the central naphthalene diimide unit and the acetylene groups. The obtained thermally stable and soluble compounds undergo reversible reduction with electron affinities of 4.18 to 4.28 eV. They emit green light with photoluminescence quantum yields of ca. 6 % in chloroform and in the range 3–12 % as thin films. The compounds were applied as emitting layers for both nondoped and doped single‐layer organic light‐emitting diodes (OLEDs) fabricated by solution processing. Under an applied external voltage, they exhibit orange or red electroluminescence.