Papers by Keyword: Copper

Abstract: Archaeometallurgical copper-artefacts contain a wide variety of metal admixtures (e.g. Pb, Bi, As, Sb, Sn) which either originate from the ores or were intentionally added. When the melt solidifies, these elements can accumulate in different structural areas and form special phases. The different alloying elements also interact with each other. In order to be able to examine these interactions, model alloys with different elements (Pb, Bi, As, Sb, Sn) and concentrations (5 or 10 wt.% each) were produced. More simple alloys show a dendritic microstructure and the added elements accumulate in the interdendritic areas. This is clearly visible for Pb and Bi additions, as both metals are not soluble in copper. As and Sb form compounds with Cu which precipitate mainly in the interdendritic regions. Sn is soluble in Cu at lower concentrations and Cu-Sn phases are formed only at higher concentrations. The resulting microstructures become very complex if more elements are involved. Finally, they enable us to have a better understanding for microstructures of ancient copper alloys.

Abstract: This study aims to develop an innovative natural rubber latex foam (NRLF) composite by incorporating coconut shell activated carbon (Ac) and 2% copper-modified Ac (2%Cu/Ac). The NRLF was prepared using the Dunlop process and mixed with Ac and 2%Cu/Ac at concentrations of 0, 5, and 10 phr. The mechanical properties, morphology, crosslink density, and cadmium ion adsorption performance were investigated. SEM analysis revealed that the additives improved the stability of the foam’s open-cell structure. The results demonstrated that copper particles deposited on Ac enhanced the overall properties of the NRLF composite. The mechanical strength at 50% strain increased significantly, from 5.81 mN/m² for neat NRLF to 12.81 mN/m² with the incorporation of 10 phr 2%Cu/Ac. Crosslink density also improved with the addition of Ac and further increased with Cu-modified Ac. In terms of cadmium adsorption, the optimal performance was achieved with 5 phr 2%Cu/Ac, yielding an adsorption capacity of 0.89 mg/g. These findings highlight the potential of 2%Cu/Ac as a superior additive for enhancing the Cadmium adsorption and the performance of NRLF composites.

Abstract: Brown seaweed (Sargassum sp.) is one of the most abundant biomass wastes widely available along the Philippine coast and has potential for alginate production. This alginate is a natural polysaccharide, having potential properties in adsorbing contaminants, such as heavy trace metals, through to its properties. In this study, pure sodium alginate (Na-ALG) was extracted and characterized from Sargassum sp. via modified Microwave-Assisted Extraction (MAE), an inexpensive and efficient method for extraction. The Cu (II) ion adsorption capability of the extracted Na-ALG in an aqueous solution was also investigated to address the increasing levels of harmful metals (i.e. Cu) on the coast of Batangas, Philippines. The novel extraction process yielded 44.0±10.8% Na-ALG, with desirable physicochemical properties. Also, Na-ALG’s surface morphology, functionalities, and crystallinity index attested to its capability to adsorb contaminants, such as heavy metals, which is through the presence of pores, functional groups of COO-, and semi-crystalline structures, resulting in adsorption-surface complexation, ionic exchange, and electrostatic interactions. Moreover, the adsorption parameters of Cu (II) concentration, Na-ALG dosage, contact time, and pH were investigated and optimized using the Response Surface Methodology Central Composite Design (RSM-CCD). The optimized adsorption process resulted in a metal concentration of 30 mg/L, alginate dosage of 2.5 g, contact time of 120 min, and pH of 3, exhibiting good adsorption efficiency of 35.96%. Thus, the results proved the adsorption efficiency based on each parameter, and the relationship of the Na-ALG properties to its Cu (II) ion adsorption capability in an aqueous medium. Conclusively, this study showed that Na-ALG extracted from Sargassum sp. via MAE can efficiently adsorb Cu (II) ions in aqueous solutions.

Abstract: Heat pumps are rapidly emerging as a crucial solution in the pursuit of decarbonization, offering significant advantages over traditional boilers due to their superior energy efficiency. The outdoor unit of a heat pump consists of around twenty key components, including a complex network of copper pipes and sheets welded to valves, connectors, and other fittings. With over thirty welded joints, there is substantial potential to reduce manufacturing time through process optimization. Copper, known for its excellent thermal and electrical conductivity, is essential in many applications. However, these same properties make welding copper particularly challenging, especially when automating industrial processes. This study explores the ultrasonic welding of copper, aiming to determine the optimal parameters for maximizing the mechanical strength of overlapping sheet joints. The optimal parameters identified for the welding process are as follows: a welding time of 3 seconds, a pressure of 6 bar, a retention time of 0.62 seconds, an initial pressure of 2 bar, a retention pressure of 2 bar, and a rising pressure for the sonotrode of 3 bar.

Abstract: This study reports the development of an elastomeric dielectric material based on natural rubber (NR) composites reinforced with copper-modified activated carbon (Cu-Ac) derived from coconut shells. The Cu-Ac content was varied systematically (0, 5, 10, and 15 phr) at a fixed Cu concentration (2 wt%). The investigation focused on the influence of Cu-Ac content on various material properties, including curing time (tc⁹⁰), density, crosslink density, mechanical behavior, morphology, and dielectric response. The results revealed a significant impact of Cu-Ac content on the curing process, with an observed decrease in t_c90 at higher Cu-Ac loadings (10 and 15 phr). However, crosslink density exhibited a decreasing trend with increasing Cu-Ac content. Encouragingly, the inclusion of Cu-Ac demonstrated a positive influence on the mechanical properties of the composite. Notably, the dielectric properties confirmed the effect of Cu-Ac on NR, with enhancements observed within the frequency range of 1.35 to 2.03 GHz. This study provides valuable insights into the influence of Cu-Ac content on NR composites, suggesting their potential for improved performance in dielectric applications.

Abstract: Copper and stainless steel possess distinct properties that make them suitable for different applications (i.e. e-mobility, nuclear power plants, etc.). However, the high thermal conductivity of copper presents a significant challenge in welding. In fact, researchers have explored various fusion welding processes for joining copper to steel and concluded that fusion welding is generally difficult or even unsuitable for obtaining sound and defects free joints. The present study investigated the feasibility of dissimilar lap joint between copper and stainless-steel thin plates using Cold Gas Tungsten Arc Welding (CGTAW) without a filler material and with no significant geometrical distortion of welded plates. The weld was created by consecutive partially overlapped spots, whose welding time varied between 100 and 150 ms, in upgraded conventional TIG machine equipped with cold TIG welding function. Samples made with 150 ms welding time showed a near-uniform distribution of equiaxed copper grain microstructure, while those obtained with 100 ms exhibited significant differences in grain size with the presence of steel inclusions in globule and vortex shapes. The joints demonstrated exceptional flexibility, allowing it to be bent up to a 180º angle without any visible damage. The maximum tensile strength of sample obtained with a welding time of 150 ms was 220 MPa with a fracture located in the heat-affected zone. The sample welded with a welding time of 100 ms exhibited 171 MPa of tensile strength with the fracture along the melting spot area due to pronounce mixing of welded materials. All the samples showed ductile behavior in the fracture zone. Eventually, the application of CGTAW resulted in promising at obtaining joint with good mechanical properties.

Abstract: This study proposes a simple method for fabricating metal particles. Metal nanoparticles are synthesized in an aqueous solution. The synthesis method is based on the galvanic replacement of one metal with another, i.e., the deposition of a metal on the surface of another metal using difference between the standard electrode potentials of the metals under ultrasonication. An aqueous colloidal solution of metallic copper (Cu) nanoparticles is prepared using Cu acetate and a metallic zinc (Zn) plate. A similar colloidal solution of metallic Cu nanoparticles is prepared using Cu acetate and a metallic iron plate. No metallic nanoparticles are obtained using metallic aluminum and nickel (Ni) plates because of the formation of passivated layers. An aqueous colloidal solution of metallic Ni nanoparticles is prepared using Ni acetate and a metallic Zn plate; however, Ni_0.7Zn_0.3O is also formed. The results of the study show that the proposed method can be used to produce metallic particles in a simple manner.

Abstract: Sequel to all the published facts on the hydrothermal of pure water on a permeable expanding/contracting surface with thermodynamic irreversibilities convey iron (III) oxide and copper hybrid nanoparticles as applicable in industry and engineering, nothing is known about the importance of viscous dissipation and the Joule heating. The current paper addresses the natural convective flow of pure water, / nanofluid and-hybrid nanofluid, (a novel advanced nanofluid composited of and nanoparticles) induced by a non-linearly stretching permeable sheet with velocity slip using a numerical scheme. The equations obtained are solved numerically via Galerkin Weighted Residual Method (GWRM), in the limiting sense, the present results conform with the existing work. Analyses reveal that a 20% concentration of nanoparticles in a base fluid is more effective in the augmentation of heat transfer than a 10% concentration. Also, the nonlinearity parameter increased the heat transfer rate for the hybrid nanosuspension. The report of this study will be of benefit to chemical engineering and nanotechnology advancement.

Abstract: Intensive global research is focused on advanced conductive materials to meet the electrical requirements of the telecommunication and power industry. The primary aim is to enhance electrical conductivity, resulting of improved current-carrying capacity and reduced energy loss during transmission. Copper and its composites are vital for power transmission and telecommunications due to their electrical, thermal, and mechanical qualities. However, current methods have drawbacks, such as compromised conductivity with alloying. Graphene, an extraordinary carbon allotrope with exceptional properties and high conductivity, offers promising opportunities for the development of superior materials; such as graphene-incorporated copper (GrCu). The incorporation of graphene into copper wire holds significant potential for various industries, including electronics, energy transmission, and telecommunications, where high conductivity and reliability are paramount. This study investigates GrCu characteristics through mixing graphene and copper, vacuum melting, fine copper wire drawing, and GrCu coaxial cable manufacturing. Graphene infusion enhances conductivity and mechanical properties, altering microstructure and inducing twin boundaries in copper grains. Graphene's disruption during wire drawing triggers this effect, elevating wire conductivity to 103.5% by IACS. GrCu coaxial cable demonstrates performance coherence with HFSS simulation up to 6 GHz. Graphene's inclusion offers tailored material properties. Ongoing research promises further optimization and advancement of graphene-copper composites, paving the way for novel technological progress.

Abstract: Copper and its salt are remarkably non-toxic to mammalian tissue. It is possible to ingest a large number of soluble copper salts such as copper sulphide to produce intoxication, nausea, vomiting, diarrhoea, and abdominal cramp. Copper salts are widely employed in agriculture and veterinary practice. Copper is an essential trace element in life and is a component of several metalloenzymes and other proteins such as cytochrome oxidase, heamocyanin, lysin oxidase, ascorbate oxidase and amine oxidase. When copper is present in the body above a particular dosage of greater than 100ppm in rats, it becomes fatal to rats. Copper is transported by blood, and is distributed to tissue and organs which have different retention capacities with the highest level of copper found in the liver, kidney, spleen and lungs. This study investigated the toxicological effect of copper in the liver and kidney of animals, using albino rats as the experimental animal. The serum chemistry report showed that the protein value of the liver homogenate for most of the experimental rats was higher than that of the control whereas the value of globulin for the control was similar to that of the experimental rats. The kidney homogenate revealed that Calcium ion has higher contents in the experimental rats than that in the control. In conclusion, the effect of copper varies with the groups of rats as compared to the control.