Papers by Keyword: Copper

Abstract: Solid-state diffusion bonding effectively joins dissimilar materials, even with varying metallurgical properties and melting points. In this study, a Cu/Ni joint was produced at a bonding temperature of 950°C for 60 minutes under a vacuum. The microstructural and mechanical properties of the bonding interface were evaluated using scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS), microhardness tests, and X-ray diffraction (XRD). It was found that the EDS point scan analysis revealed the formation of a solid solution of Cu-Ni at the bonding interface. Since Cu-Ni exhibit complete solubility with each other, no intermetallic compounds (IMCs) were formed. The microhardness indicated that the bonding interface had a microhardness of 20% and 54% higher than the base metals (BM) of Ni and Cu, respectively.

Abstract: An experimental method to calculate average charge of metal ions by electrolysis at different temperatures is proposed. Aluminium undergoes dissolution to the Al³⁺ ions at all temperatures. Iron undergoes dissolution to the Fe²⁺ or the Fe³⁺ ions and copper undergoes dissolution to the Cu⁺ or the Cu²⁺. It depends on temperature and electric current density. Direct electric current value and anode mass decreasing were measured during electrolysis into concentrated NaCl solution in water (5 mol/kg or 23.1%, freezing point equals -22°C, pH 6.5–7.5) at room temperature and 100°C. The average charges of copper, iron, and aluminium ions were calculated using Faraday’s law of electrolysis at electric current density 3,000 A/m² (or 30 A/dm²): +3 for aluminium; +2 for iron; and +1 for copper at room temperature, and +3 for aluminium; +2 for iron; and +1.5 for copper at temperature 100°C. The main condition was z_Al=3. We concluded that calculations of the average metal ions charges, z_Fe and z_Cu, were correct since z_Al=3. The result is as follows: the Al³⁺, the Fe²⁺, and the Cu⁺ ions dissolve into concentrated NaCl solution in water at room temperature; the Al³⁺, the Fe²⁺, the Cu⁺ and the Cu²⁺ ions (50%/50%) dissolve into the solution at temperature 100°C. We have obtained experimentally and by mathematical modelling that aluminium anodes (cylindrical or spherical) dissolve into the solution more rapidly with temperature increasing during electrolysis accordingly to the Arrhenius law, while copper anodes (cylindrical or spherical) dissolve more slowly with temperature increasing from room temperature to temperature 180°C like “inverse Arrhenius law”. Iron electrochemical corrosion rate practically does not depend on temperature below 100°C (and, obviously, up to 180°C) like “zeroth Arrhenius law”. The spherical anode effect is greater than the cylindrical anode effect in 1.5 times.

Abstract: The extraction and processing of silver minerals produce significant amounts of waste, which poses environmental challenges due to their low metal content and the potential release of toxic elements. The study investigates the application of Acidithiobacillus ferrooxidans (AF) bacteria to the bioleaching of these waste materials, with the aim of maximizing the recovery of iron, copper and arsenic. The objectives of the study include characterizing waste materials, optimizing the bioleaching process parameters and evaluating metal extraction efficiency. The samples were leached with additives (CuSO₄ 5H₂O and AgNO₃) to accelerate the kinetics of metal dissolution in solution and reduce the bacterial leaching time. The results showed that samples 1-2 and 2-2 containing additives had higher values of dissolved iron and copper in the leachate compared to samples 1-1 and 2-1 without additive application.

Abstract: This study utilized friction stir welding for butt joining of A1050 and C1020 plates, investigating the effects of cold rolling and annealing on the structure of the bonding interface and the hardness of the materials. The experiments revealed successful joint formation with minimized copper dispersion in aluminum and the formation of intermetallic compounds. Cold rolling resulted in increased hardness without significant crack propagation along the bonding interface. Annealing effectively reduced the difference in hardness, indicating that copper recrystallizes earlier than aluminum.

Abstract: In this paper, the effect of rotary friction welding on hardness and microstructures of weld zones and base metal zones of Ti-6Al-4V and Cu have been investigated. A rotary friction welding technique was used to perform dissimilar joining of Cu and Ti-6Al-4V bars. Friction welding process parameters were optimized process parameters of a 5-ton rotary friction welding machine. The upset pressures were applied from 30 kg/mm^2, 40 kg/mm² and 50 kg/mm². The dissimilar joint was successfully formed at upset pressure of 50 kg/mm². The friction welded joints were failed in drop test after welding at the lower upset pressures (30 kg/mm² and 40 kg/mm²).The hardness and microstructures were characterized for weld joint formed at 50 kg/mm². The weld zone, base metal and weld interface and base metals were analysed to understand microstructures and elemental diffusion of Ti and Cu. The welded specimens were examined by using an optical microscope and scanning electron microscope. Grain refinement was seen in Cu near the interface of the joint whereas in the case of titanium circular patterns of grains were seen near the interface of the joint. The micro hardness of Ti-6Al-4V was increased from 307 HV to 365 HV and for Cu increased from 240 HV to 290 HV. Intermetallic compounds such TiCu₄ and Ti₂Cu were found at weld zone by X-ray diffraction analysis.

Abstract: Recently, copper (Cu) and silver (Ag) nanowires have been widely employed as conductive fillers in flexible electronic devices due to their high aspect ratios leading to the formation of conductive networks in a polymeric substrate. This study combined Cu and Ag as a 1-dimensional nanostructures through galvanic replacement with a core-shell configuration. The effects of the galvanic replacement factors on the Cu-Ag core-shell nanostructures morphology was studied by varying the reaction time, temperature, and Ag concentration. SEM images show a more extensive Cu dealloying and Kirkendall voiding with longer reaction times, resulting in the Cu core dissolution. Homogenous nucleation of Ag occurs at higher reaction temperatures and Ag concentrations, producing separate Ag particles.

Abstract: A novel add-on hardware device is placed near the point of slurry dispense that can instantaneously activate slurry performance during polishing via megasonic irradiation. This new technology (Flucto-CMP® is able to overcome the inherent polisher-slurry weaknesses such as wafer-level defects, process vibrations, cost of ownership, slurry waste, remval rate (RR), and RR selectivity. Flucto-CMP® has been successfully applied to various types of CMP slurries resulting in significant increases in the removal rates of copper, SiC, borosilicate hard mask, ILD, TiN, and silicon carbide through chemical alteration of the passivation layer needed for material removal. Specifically, for copper CMP, using Flucto-CMP®, we see an up to 31% boost in RR which is well correlated with the amount of reactive oxidizing species generated through irradiation as well as the measured relative indentation depth of the passivation layer. In addition to boosts in RR, for copper, we see a 50X drop in the variance of shear force and a 5X drop in the variance of normal force when Flucto-CMP® is used. This dramatic reduction in process vibration for copper soft-landing processes ought to reduce wafer-level defects. Much greater rate improvements are observed when polishing SiC, and borosilicate hard masks.

Abstract: Chitosan/Alginate Nanoparticles (CANPs) were produced via microemulsion method. SEM images captured that CANPs has rough, irregular, and porous surfaces. The particle sizes were in the range of 1-15 nm with an average diameter of 8.31 nm. CANPs were applied for trace metals removal. Optimum adsorption capacity of Zn(II) and Cu(II) were 8.144 and 5.582 mg g^-1, respectively. Kinetic studies show that the adsorption of Zn(II) and Cu(II) onto CANPs fitted pseudo second order model. Isotherm studies determined that the sorption followed Dubinin-radushkevich model. Zn(II) adsorbed CANPs (Zn/CANPs) and Cu(II) adsorbed CANPs (Cu/CANPs) were investigate their antibacterial activity againts E. coli and S. aureus. Zone of Inhibition (ZOI) of Zn/CANPs were 19.3 mm (E. coli) and 17.5 mm (S. aureus). ZOI of Cu/CANPs were 14.17 mm (E. coli) and 10.75 mm (S. aureus). The results revealed that CANPs were a promising bifunctional material for metals removal and has good antibacterial activity.

Abstract: Lacquered copper membranes are sometimes used in operate equipment containing low aggressive corrosive water-based fluids. In some cases, the lacquer coating does not prevent the occurrence of corrosive processes leading to through damage to the product and equipment failure. In this work, a review of the most common copper corrosion mechanisms is carried out. During a visual inspection of the products, the peculiarities of the state of the membrane surfaces and corrosive damage were noted. On the basis of metallographic, X-ray structural and electrochemical studies, the assumptions put forward at the stage of visual inspection were confirmed. The conclusions contain assumptions about the reasons for the formation of pitting corrosion on copper membranes.

Abstract: This study aims to determine the effect of installing modified copper C-SiO₂-ZSM5 in the exhaust, installing modified copper in the exhaust to reduce CO and HC. The two methods used to reduce CO and HC exhaust emissions are as follows: the first method is by mixing fossil fuels with ethanol. The fuel used is a mixture of gasoline + ethanol with variations of gasoline, E10, and E20. The second method is to provide a CO and HC reformer catalyst made of modified copper with the addition of SiO₂ and MZM5 as much as 10% and 20%, respectively. The test uses a four-stroke two-wheel motor in a neutral gear position. Exhaust emission data retrieval is at 1500, 3000, 5000, 7000, 9000 rpm. With gasoline fuel mixed with ethanol with E 10 and E 20. There is a decrease in CO at each engine speed in each fuel variation, because the more ethanol content, the greater the supply of O₂ in combustion because ethanol has oxygen bonds that can increase combustion. The emission of CO and HC gas on gasoline-fueled motors are greater than those of E 10 and E 20 motors. The use of a copper converter catalyst SiO₂-C-ZSM5 is very significant and can reduce CO levels for gasoline fuel from the highest value of 4,7% to 2.82%, gasohol fuel E 10 with the highest value of CO 3.02% decreased to 1.2% and gasohol fuel E 20 the highest value of CO 2.78% decreased to 0.17%. Changes were seen visually on the surface of the copper used for the CO and HC reduction test, the surface copper became darker in color, especially when testing using gasoline. When using a mixture of ethanol and gasoline, copper is purplish brown color.