Copper Metal Powder Research Articles

A new strategy for immobilization of copper on the Fe3O4@EDTA nanocomposite and its efficient catalytic applications in reduction and one-pot reductive acetylation of nitroarenes and also N-acetylation of arylamines

A new and efficient Cu(II)-containing mesoporous nanocatalytic system was synthesized by direct immobilization of copper metal powder on the Fe3O4@EDTA nanocomposite. The as-prepared Fe3O4@EDTA@Cu(II) nanocomposite was then characterized by FT-IR, XRD, SEM, TEM, SEM-based EDX and elemental mapping, XPS, TGA, VSM, and also BET and BJH analyses. The resulting Fe3O4@EDTA@Cu(II) mesoporous nanocomposite exhibited satisfactory catalytic activity towards the reduction and one-pot reductive acetylation of nitroarenes and also N-acetylation of arylamines in water at 60 °C. Notably, the applied Cu(II)-containing nanocatalyst was efficiently recovered from the reaction mixture using an external magnetic field and could be reused successfully for five cycles. The protocol developed in this study offers several advantages in terms of mild reaction conditions, simple workflows, using water as a green solvent, and easy recovery and catalyst reuse, making it more ecologically and economically attractive.

Chemical Behaviour of Copper in the Application of Unconstrained Cr-Ni-Al-Cu Metal Powders in Submerged Arc Welding: Gas Phase Thermodynamics and 3D Slag SEM Evidence

Unconstrained metal powders of Cu, Cr, Ni and Al were applied to submerged arc welding (SAW) to clarify the chemical behaviour of copper in this modified SAW process. Aluminium metal is avoided in SAW because it is easily oxidised. Excessive aluminium oxides in the form of slag or inclusions in the weld metal will lead to poor weld metal materials properties. Aluminium is an effective deoxidiser and can be used to prevent Cr and Ni loss to the slag by preventing oxidation of these metals. The results show that carbon steel was alloyed to 5.3% Cr, 5.3% Ni, 3.6% Al and 5.2% Cu at 80% Cr yield, 81% Ni yield, 54% Al yield and 79% Cu yield. BSE (backscattered electron) images of the three-dimensional (3D) post-weld slag sample show 3D structures within the slag dome. The 3D structures contain features of vapour formation and recondensation. In addition, nano-strands appear in the 3D structures and confirm the vaporisation and recondensation of fluorides. The chemical behaviour of copper metal powder added in SAW is to vaporise as metallic copper and incorporate in the Al-Si-Mg-Ca-Mn-Fe-Cu-Na-Cr-Ni fluoride. Copper, in combination with aluminium, has a stabiliser effect in SAW due to its formation of an initial alloy melt of low liquidus temperature, thus decreasing the temperature required to melt high-melting-point metals such as Cr into the weld pool. Although Al and Cu have similar vapour pressures at specific temperatures, it appears that Cu does not substitute for Al in the gas phase. Gas-slag-alloy thermochemical equilibrium calculations confirm the partial oxygen pressure lowering effect of aluminium and the vaporisation of copper as metallic copper with very little copper-fluoride species expected to form. The quantity of metallic copper vaporisation calculated in the gas-slag-alloy thermochemical equilibrium is much higher than the vaporisation quantity measured in welding. This may be due to recondensation of vaporised copper which is not accounted for in the equilibrium calculation at the set arc cavity temperature, as well as the effect of surface-active elements such as sulphur and oxygen in limiting the vaporisation reaction of copper.

Study of joining copper-mild steel using microwave energy

In the present work, joining of dissimilar metals using electromagnetic energy has been successfully achieved. A 900 W multimode microwave applicator at the fixed frequency of 2450 MHz was used to generate the required heat energy for joining. Copper (Cu) and mild steel (MS) were chosen as the base material to be joined. Copper metal powder in the form of the thick slurry was prepared and used as a joining agent between two bulk interfaces. The joining process was carried out through the controlled emission of microwaves at a particular area for a particular period of time. Due to these controlled emissions of microwaves, the slurry of metal powder got melted and produced a fine bond with the bulk interfaces on cooling. To understand the nature of the joint formation, joints were characterized by using an optical microscope, SEM, X-ray diffractometer, microhardness tester, and Universal testing machine. Analysis of SEM resulted in a well-defined, merged, and fused joint. The microhardness at the joint zone was recorded to be 73 ± 4 HV and 78 ± 6 HV on copper side and MS side respectively. Strength test results showed the UTS of 170 MPa with 13.25% elongation.

Characterization of the Native Oxide Shell of Copper Metal Powder Spherical Particles.

The native oxide layer that forms on copper (Cu) metal spherical particle surfaces under ambient handling conditions has been shown to have a significant effect on sintering behavior during microwave heating in a previous study, where an abnormal expansion was observed and characterized during sintering of Cu compacts using reducing gases. Because microwave (MW) heating is selective and depends greatly on the dielectric properties of the materials, this thin oxide layer will absorb MW energy easily and can consequently be heated drastically starting from room temperature until the reduction process occurs. In the current study, this oxide ceramic layer was qualitatively and quantitatively characterized using the carrier gas hot extraction (CGHE) method, Auger electron spectroscopy (AES), and a dual-beam focused ion beam (FIB)/scanning electron microscope (SEM) system that combines both FIB and SEM in one single instrument. Two different commercial gas-atomized spherical Cu metal powders with different particle sizes were investigated, where the average oxygen content of the powders was found to be around 0.575 wt% using the CGHE technique. Furthermore, AES spectra along with depth profile measurements were used to qualitatively characterize this oxide layer, with only a rough quantitative thickness approximation due to method limitations and the electron beam reduction effect. For the dual-beam FIB-SEM system, a platinum (Pt) coating was first deposited on the Cu particle surfaces prior to any characterization in order to protect and to preserve the oxide layer from any possible beam-induced reduction. Subsequently, the Pt-coated Cu particles were then cross-sectioned in the middle in situ using an FIB beam, where SEM micrographs of the resulted fresh sections were characterized at a 36° angle stage tilt with four different detector modes. Quantitative thickness characterization of this native oxide layer was successfully achieved using the adapted dual-beam FIB-SEM setup with more accuracy. Overall, the native Cu oxide layer was found to be inhomogeneous over the particles, and its thickness was strongly dependent on particle size. The thickness ranged from around 22–67 nm for Cu powder with a 10 µm average particle size (APS) and around 850–1050 nm for one with less than 149 µm.

Atmospheric air plasma sustainment by semiconductor microwave for hydroxyl radical production and powder metal element analysis

A semiconductor microwave device that generates a series of burst microwaves at a sub-microsecond duration has been successfully used in a breakdown plasma spectrometer in atmospheric conditions. Microwave delivery has been changed to couple the microwave with laser sparks and electric sparks which are typical plasma ignition sources in laser-induced breakdown spectroscopy (LIBS) and spark-induced breakdown spectroscopy (SIBS). A helical antenna was used for the laser spark, while a coaxial antenna was considered more appropriate for the electric spark. The weak and transient sparks in LIBS and SIBS are enlarged by the microwaves which are stably sustained in the air. The microwave's output power and pulse duration are easily controllable, resulting in tunable plasma intensity and sustained production of hydroxyl radicals (OH radicals). Even in continuous-wave operation by microwave, the low-energy system prevented the formation of high-temperature thermal plasma (>10,000 K) without any mechanical cooling system. The microwave-enhanced LIBS (MW-LIBS) and microwave-enhanced SIBS (MW-SIBS) could be applied to optical emission spectroscopy analyses. In analytical applications, MW-SIBS produces no shockwave in contrast with MW-LIBS which is a great advantage in powdered samples. The MW-SIBS successfully analyzed the direct introduction of copper metal powders.

Study on fabrication of copper metal powder/epoxy resin composite conductive glue as electrical contacts of the brush to engine

In this paper, the effect of copper metal powder and epoxy resin mixture on the fabrication process of the conductive glue system as electrical contact part of the brush to the engine on the naval battleship was studied. The copper metal/epoxy ratio in the glue was adjusted from 40 to 85 wt%, then evaluated by determining structure, conducting, and other mechanical properties. The optimal glue system has a very small electrical resistance of 0.0010 Ω, and a wire pulling force of 486.0 N. Results showed that the copper metal powder/epoxy composite glue system has properties equivalent to the currently used Russian product.

A performance study of electrochemical micro-machining on SS 316L using suspended copper metal powder along with stirring effect

ABSTRACT Electrochemical micro-machining (ECMM) is widely used for machining small-sized components, intricate shapes, and hard materials. Fabrication of micro-holes in stainless steel 316L (SS 316L) can be effortlessly achieved by the ECMM process rather than other machining methods, owing to its favorable machining characteristics and advantages. This paper tries to elucidate the performance of ECMM on the machining of SS 316L using an eco-friendly citric acid as an electrolyte medium, and the results are compared with copper metal powder suspended in a citric acid electrolyte (suspended electrolyte) and copper metal powder suspended in a citric acid electrolyte with the assistance of a mechanical overhead stirrer (suspended electrolyte with stirrer effect). The output performance parameters such as MRR and overcut are calculated by varying the input response parameters such as machining voltage, duty cycle, and electrolyte concentration. From the experimental results at higher parameter levels, the highest MRR and moderate overcut are obtained for suspended electrolyte with stirrer effect. For suspended electrolyte, moderate MRR and the highest overcut are detected. The least MRR and reduced overcut are found for citric acid electrolyte. SEM and EDAX analysis have been carried out to see the machined micro-hole and the composition present in the specimen.

Characterization of the Native Oxide Shell of Copper Metal Powder Spherical Particles

Characterization of the Native Oxide Shell of Copper Metal Powder Spherical Particles

Ecologically friendly production of copper powder and elimination of cupric ions from aqueous solutions using D-Glucose and ascorbic acid

Copper(II) ions (Cu2+) in copper sulfate solutions (CuSO4) can be reduced with several carbohydrates to produce copper metal powder. In this study glucose was used as a reducing agent. The big challenge in this study was to find the optimum conditions for copper ions reduction because they were entwined with positive conditions for degradation and hydrolyses of sugar (D-glucose). For that reason, the impact of several parameters on these conditions was investigated in a series of experiments in this research study. The glucose concentration (0.2-1.6M), the temperature (30-70 °C), initial sodium hydroxide concentration (0.2-0.4M), the role of adding sulfuric acid (H2SO4) at different volumes (0.6-3 mL) and the addition of ascorbic acid at different doses (4-20 mL) were the considered key parameters that were studied in this research. The synthesis of copper was restricted due to organic acid build up and reactions of the degradation products and copper. Under optimum conditions using glucose as a reducing agent, maximum of 48% of copper ions were transformed to copper metal (Cu). By adding ascorbic acid at the end of the experiment process, reduction efficiency was 100% where total and complete copper reduction was achievable. Most of solid particles were analyzed and the characterization and nature of the produced solid was achieved by X-Ray Diffraction.

Morphological studies and wear behavior of electro discharge coated steel

This paper elaborates on the deposition of tungsten and copper (W-Cu) material on the AISI 1020 steel substrate and the method used for deposition with its surface and wear characteristics. The tool electrode used is of tungsten copper (W-Cu) manufactured by powder metallurgy (PM) route with different ratios of tungsten and copper metal powders. The process carried out for deposition is by electro-discharge coating (EDC). In this, the tool electrode material is melted and deposited on the substrate by the application of heat energy due to sparking between the electrode and the substrate. Then a thick layer of W-Cu coating is formed on the substrate material. The substrate material of AISI 1020 steel was cut in cylindrical shapes of 10 mm diameter and height 10 mm by wire cut EDM machine and was then surface grinded for the accuracy and polished surface. The cylindrical size was considered for holding the specimen in the clamping device of wear testing machine easily during wear testing. The wear behavior of the coated samples is assessed by the pin on disc method. The effect of mixing ratio, micro hardness, Scanning Electron Microscope (SEM), Energy Disperse Spectroscopy (EDS) analysis, Coefficient of friction (COF) etc., for different composition coated samples has been investigated. The results show that the micro hardness achieved in the range 51-84HV for coated specimens of W-Cu of different composite substrates. The COF was achieved in the range of 0.16 to 0.31 after wear experimentation. The microstructures of the coated samples are analyzed before and after wear by using SEM and EDS.

Evaluation of Mechanical Properties of Banana and Glass-Epoxy Hybrid Composites with Addition of Copper Powder

More studies have been made in recent years on the fibre reinforced polymer. Natural fibres play an important role in modern FRPs. To obtain higher mechanical properties, glass fibres are incorporated to prepare hybrid FRP composites. Present study, focuses the effect of adding the copper metal powder in polymer matrix i.e. the metal powder is mixed in the resin with varying proportions along with the banana and glass fibres. Five laminates were fabricated by varying the copper content from 1% to 5% and keeping the banana and glass fibres weight as common. The study concentrates on mechanical properties of the obtained hybrid composites. Good flexural and ultimate tensile strengths were obtained. The flame deflection test shows the hybrid composite is not suitable for high temperature application as it breaks the bond between the resin and the reinforcements due to thermal conductivity of copper.

Experimental evaluation of hybrid composites by the Cu addition

Abstract Natural fibers plays an important role in modern FRPs. To obtain higher mechanical properties glass fibers are incorporated to prepare hybrid FRP composites. This study, focuses the effect of copper metal powder in the polymer matrix i.e. the metal powder is mixed in the resin itself with varying proportions along with the banana and glass fibers. The study concentrates on mechanical properties of the obtained hybrid composites suited for automotive applications. The result showed better mechanical properties.

Experimental evaluation on natural composites with the incorporation of metal powders

Abstract The study is based on the investigation of mechanical properties in hybrid FRP which is fabricated with epoxy polymer, natural and glass fibres, and addition of silicon and copper powder. The natural fibres of chopped banana fibres were also reinforced for increasing the strength of composites. The E-glass fibre were added and analysed its properties. The result showed that, the mechanical properties were improved due to the silicon and copper metal powder additions. The water absorption test was also taken and found the improvement in the hybrid composites due to the added metal powders.

Study of effect of Al and Cu microparticles dispersed in D-Mannitol PCM for effective solar thermal energy storage

A practical use of phase change material (PCM)-based thermal energy storage (TES) system is effectively employed for mitigating the imbalance between energy demand and energy supply. Technological development of TES is essential to overcome the drawback of the poor thermo-physical property of many PCM’s. Otherwise, the PCM-based TES system would exhibit poor thermal management. In this work, D-Mannitol (DM) sugar alcohol is considered as PCM and experimental attempts were made to accelerate the phase change behaviour of the chosen PCM by adding 1 and 2% mass fraction of micron-sized copper and aluminium metal powders. The phase change temperature and enthalpy of fusion of the plain DM and composite DM were determined by differential scanning calorimetry (DSC) measurements, and the thermal stability of composite PCM was analysed using thermogravimetric analysis (TGA). Further, charging and discharging processes were conducted for plain DM and composite DM using Therminol 55 heat transfer fluid (HTF) to study their thermal energy storage performance. The DSC results indicated superior enthalpy of fusion and phase transition temperature and TGA results depicted extended decomposition temperature with an increase of about 2 °C to 32 °C for composite DM, respectively, over plain DM. Further, from charge–discharge studies, it was identified that the total time taken for a complete phase change process for the case of DM-Cu 2% during charging process was 22% and 11% lesser compared to plain DM and DM-Al 2%, respectively. Similarly during discharging process, the total time taken for a complete phase change process of DM-Cu 2% was 16% and 10% lesser compared to plain DM and DM-Al 2%, respectively, indicating superior phase change behaviour of composite DM compared to the plain DM. Thus, when compared to plain DM and Al microparticle in DM, Cu microparticle added DM was found to be more suitable to store thermal energy at a medium temperature range.

Copper(II) oxide nanocatalyst preparation and characterization: green chemistry route

BackgroundGreen synthesis as a technique of preparation of metal/metal oxide nanomaterials is becoming an important and competitive method of preparation replacing the conventional method of preparation. Among metal oxides, nanocatalyst copper(II) oxide is considered as a very important and potent catalyst/photocatalyst with a very wide range of applications.ResultsIn this work, copper(II) oxide nanoparticles were prepared with the assist of aqueous spinach extract from copper metal powder. Spinach extract catalyzes the formation of copper oxide nanoparticles with manipulation of chlorophyll that exists in the extract. The produced copper(II) oxide nanoparticles were characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD).ConclusionsIt was proved that spinach extract catalyzes the preparation of copper(II) oxide nanocatalyst. It was elucidated from the characterization technique that the produced nanoparticles are pure copper oxide with particle size range of 60–100 nm.

Mechanochemical transformation of ZnO2 to highly defective ZnO

The mechanochemical reaction of zinc peroxide (ZnO2) with zinc (Zn) and copper (Cu) metal powders was examined. Ex-situ characterization of samples was adopted to monitor the progress of reaction and to determine the nature of final product. Cubic ZnO2 transformed to hexagonal ZnO after grinding for 4 h. Band gap of the sample, determined by Kubelka-Munk function, was 3.02 eV. Vibration modes at 509 and 557 cm−1 due to defects were prominent for this sample in its Raman spectrum. This was endorsed by intense emission at 440 nm in the photoluminescence spectrum as well. The reaction of ZnO2 with Cu powder was slow and completed after grinding for 11 h yielding hexagonal ZnO. Doping of Cu2+ for Zn2+ in ZnO was confirmed from reduction in the band gap as compared with bulk ZnO. High concentration of defects manifested as emissions at 377, 409 and 419 nm when excited with λ = 320 nm. Both the samples catalyzed photo degradation of Rhodamine-B (Rh-B) dye solution. The recyclable nature of it has also been examined.

High surface area graphene foams by chemical vapor deposition

Three-dimensional (3D) graphene-based structures combine the unique physical properties of graphene with the opportunity to get high electrochemically available surface area per unit of geometric surface area. Several preparation techniques have been reported to fabricate 3D graphene-based macroscopic structures for energy storage applications such as supercapacitors. Although reaserch has been focused so far on achieving either high specific capacitance or high volumetric capacitance, much less attention has been dedicated to obtain high specific and high volumetric capacitance simultaneously. Here, we present a facile technique to fabricate graphene foams (GF) of high crystal quality with tunable pore size grown by chemical vapor deposition. We exploited porous sacrificial templates prepared by sintering nickel and copper metal powders. Tuning the particle size of the metal powders and the growth temperature allow fine control of the resulting pore size of the 3D graphene-based structures smaller than 1 μm. The as-produced 3D graphene structures provide a high volumetric electric double layer capacitance (165 mF cm−3). High specific capacitance (100 Fg−1) is obtained by lowering the number of layers down to single layer graphene. Furthermore, the small pore size increases the stability of these GFs in contrast to the ones that have been grown so far on commercial metal foams. Electrodes based on the as-prepared GFs can be a boost for the development of supercapacitors, where both low volume and mass are required.

An antibacterial copper composite more bioactive than metallic silver.

Although known for its biocidal activity, copper is still not considered as a viable alternative to silver in many of its biocidal applications, mainly because it is generally considered to be a milder antibacterial metal. As copper is much cheaper than silver (1/100), it is potentially more accessible to the health and hygiene needs of third-world countries, to large volume consumer products, and to large-scale agricultural and water treatment needs. Therefore, enhancing the biocidal efficacy of copper is a sought-after goal. We report a method for achieving this goal: by entrapping molecules of the biocidal agent chlorhexidine (CH) within a metallic copper metal powder, using a new materials methodology, the antibacterial efficacy of copper towards two model nosocomial opportunistic bacteria - the Gram-negative Pseudomonas aeruginosa and the Gram-positive Staphylococcus epidermidis- is enhanced to provide a powerful antibacterial agent exceeding the activity of silver. ICP-MS elemental analysis and UV-spectroscopy indicated that the enhanced bactericidal effects of the synthesized composite, CH@Cu, are associated with the sustained release of both copper ions and CH, giving rise to synergistically enhanced activity.

The role of the native oxide shell on the microwave sintering of copper metal powder compacts

Successful microwave sintering of several metal powders had been reported by many researchers with remarkable improvements in the materials properties and/or in the overall process. However, the concept behind microwave heating of metal powders has not been fully understood till now, as it is well known that bulk metals reflect microwaves. The progress of microwave sintering of copper metal powder compacts was investigated via combining both in-situ electrical resistivity and dilatometry measurements that give important information about microstructural changes with respect to the inter-particle electrical contacts during sintering. The sintering behavior of copper metal powders was depending on the type of the gas used, particle size, the initial green density, the soaking sintering time and the thin oxide layer on the particles surfaces. The thin copper oxide native layer (ceramics) that thermodynamically formed on the particles surfaces under normal handling and ambient environmental conditions had a very critical and important role in the microwave absorption and interaction, the sintering behavior and the microstructural changes. This finding could help to have a fundamental understanding of why MW’s interact with copper metal powder in a different way than its bulk at room temperature, i.e. why a given metal powder could be heated using microwaves while its bulk reflects it.

An advanced study on the hydrometallurgical processing of waste computer printed circuit boards to extract their valuable content of metals

This study refers to two chemical leaching systems for the base and precious metals extraction from waste printed circuit boards (WPCBs); sulfuric acid with hydrogen peroxide have been used for the first group of metals, meantime thiourea with the ferric ion in sulfuric acid medium were employed for the second one. The cementation process with zinc, copper and iron metal powders was attempted for solutions purification. The effects of hydrogen peroxide volume in rapport with sulfuric acid concentration and temperature were evaluated for oxidative leaching process. 2M H2SO4 (98% w/v), 5% H2O2, 25°C, 1/10 S/L ratio and 200rpm were founded as optimal conditions for Cu extraction. Thiourea acid leaching process, performed on the solid filtrate obtained after three oxidative leaching steps, was carried out with 20g/L of CS(NH2)2, 6g/L of Fe3+, 0.5M H2SO4, The cross-leaching method was applied by reusing of thiourea liquid suspension and immersing 5g/L of this reagent for each other experiment material of leaching. This procedure has lead to the doubling and, respectively, tripling, of gold and silver concentrations into solution. These results reveal a very efficient, promising and environmental friendly method for WPCBs processing.