scholarly journals Electrochemical Behaviour of Chalcopyrite in Chloride Solutions

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 67 ◽  
Author(s):  
Luis Beiza ◽  
Víctor Quezada ◽  
Evelyn Melo ◽  
Gonzalo Valenzuela
Keyword(s):  
Current Density ◽  
Electrochemical Behaviour ◽  
Sweep Rate ◽  
Chloride Ions ◽  
Ferrous Ions ◽  
Maximum Current Density ◽  
Maximum Current ◽  
Density Values ◽  
Current Densities ◽  
Copper Ores

Due to the depletion of oxidized copper ores, it necessitates the need to focus on metallurgical studies regarding sulphide copper ores, such as chalcopyrite. In this research, the electrochemical behaviour of chalcopyrite has been analysed under different conditions in order to identify the parameters necessary to increase the leaching rates. This was carried out through cyclic voltammetry tests at 1 mV/s using a pure chalcopyrite macro-electrode to evaluate the effect of scan rate, temperature, and the addition of chloride, cupric, and ferrous ions. Lastly, the feasibility of using seawater for chalcopyrite dissolution was investigated. An increase in the sweep rate and temperature proved to be beneficial in obtaining highest current densities at 10 mV/s and 50 °C. Further, an increase of chloride ions enhanced the current density values. The maximum current density obtained was 0.05 A/m2 at concentrations of 150 g/L of chloride. An increase in the concentration of cupric ions favoured the oxidation reaction of Fe (II) to Fe (III). Finally, the concentration of chloride ions present in seawater has been identified as favourable for chalcopyrite leaching.

Facet Topography and Dislocation Structure as a Possible Source for Electrical Heterogeneity in [001] TILT Bicrystals of YBa2Cu3O7-δ

1996 ◽  
Vol 54 ◽  
pp. 338-339
Author(s):  
I-Fei Tsu ◽  
D.L. Kaiser ◽  
S.E. Babcock
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Electromagnetic Properties ◽  
Length Scale ◽  
Density Values ◽  
Current Densities ◽  
Applied Fields ◽  
A Current

A current theme in the study of the critical current density behavior of YBa2Cu3O7-δ (YBCO) grain boundaries is that their electromagnetic properties are heterogeneous on various length scales ranging from 10s of microns to ˜ 1 Å. Recently, combined electromagnetic and TEM studies on four flux-grown bicrystals have demonstrated a direct correlation between the length scale of the boundaries’ saw-tooth facet configurations and the apparent length scale of the electrical heterogeneity. In that work, enhanced critical current densities are observed at applied fields where the facet period is commensurate with the spacing of the Abrikosov flux vortices which must be pinned if higher critical current density values are recorded. To understand the microstructural origin of the flux pinning, the grain boundary topography and grain boundary dislocation (GBD) network structure of [001] tilt YBCO bicrystals were studied by TEM and HRTEM.

Controlling factors in localised corrosion morphologies observed for magnesium immersed in chloride containing electrolyte

2015 ◽  
Vol 180 ◽  
pp. 313-330 ◽  
Author(s):  
Geraint Williams ◽  
Nick Birbilis ◽  
H. Neil McMurray
Keyword(s):  
Current Density ◽  
Radial Growth ◽  
Cathodic Current Density ◽  
Nacl Solution ◽  
High Concentration ◽  
Cathodic Current ◽  
Density Distributions ◽  
Filiform Corrosion ◽  
Density Values ◽  
Current Densities

The early stages of localised corrosion affecting magnesium (Mg) surfaces when immersed in aqueous sodium chloride (NaCl) solutions involves the propagation of dark regions, within which both anodic metal dissolution and cathodic hydrogen evolution occur. For nominally “pure” Mg, these dark areas can either take the form of discs which expand radially with time, or filiform-like tracks which lengthen with time. For Mg surfaces which display disc-form corrosion features in concentrated NaCl electrolyte, a transition to filiform corrosion (FFC) is observed as the concentration is decreased, indicating ohmic constraints on radial propagation. A similar effect is observed when Mg specimens of different iron impurity are immersed in a fixed, high concentration NaCl solution, where disc-form corrosion is observed on samples having ≥280 ppm Fe, but FFC predominates at ≤80 ppm Fe. An in situ scanning vibrating electrode technique (SVET) is used to determine current density distributions within the propagating corrosion features. Cathodic current density values of between −100 and −150 A m−2 measured in central areas of disc-like features are sufficient to sustain the radial growth of a local anode at the perimeter of the discs. However, for high purity Mg specimens (≤80 ppm Fe), cathodic current densities of −10 A m−2 or less are measured over FFC affected regions, indicating that linear propagation arises when there is insufficient cathodic current produced on the corroded surface to sustain radial growth. The results are consistent with surface control of localised corrosion propagation in concentrated electrolyte, but ohmic control in dilute, lower conductivity NaCl solution.

scholarly journals Computer-based Finite Element Modeling of Insulated Tuohy Needles Used in Regional Anesthesia

2009 ◽  
Vol 110 (6) ◽  
pp. 1229-1234 ◽  
Author(s):  
Meredith B. Cantrell ◽  
Warren M. Grill ◽  
Stephen M. Klein
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Nerve Fiber ◽  
Current Density ◽  
Three Dimensional ◽  
Element Modeling ◽  
Maximum Current Density ◽  
Maximum Current ◽  
Distal Edge ◽  
Computer Based

Background Differences in needle design may impact nerve localization. This study evaluates the electrical properties of two insulated Tuohy needles using computational finite element modeling. Methods Three-dimensional geometric computer-based models were created representing two 18-gauge, insulated Tuohy needles: (1) with an exposed metal tip and (2) with an insulated tip. The models were projected in simulated human tissue. Using finite element methodology, distributions of current-density were calculated. Voltages in the modeled medium were calculated, and activation patterns of a model nerve fiber around the tip of each needle were estimated using the activating function. Results Maximum current density on the exposed-tip needle occurred along the edge of the distal tip; the distal edge was 1.7 times larger than the side edges and 3.5 times larger than the proximal edge. Conversely, maximum current density occurred along the proximal edge of the insulated-tip Tuohy opening; the proximal edge was 1.9 times larger than the side edges of the opening and 3.5 times larger than the distal edge of the opening. Voltages generated by the exposed-tip needle were larger and had a wider spatial distribution than that of the insulated-tip needle, which restricted to the area immediately adjacent to the opening. Different changes in threshold were predicted to excite a nerve fiber as the needles were rotated or advanced toward the modeled nerve. Conclusions The needles displayed different asymmetric distributions of current density and positional effects on threshold. If this analysis is validated clinically, it may prove useful in testing stimulating needles before clinical application.

scholarly journals Pt-Amorphous Barium Aluminum Oxide/Carbon Catalysts for an Enhanced Methanol Electrooxidation Reaction

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 708
Author(s):  
Tzu Hsuan Chiang ◽  
Wan-Yu Hou ◽  
Jia-Wei Hsu ◽  
Yu-Si Chen
Keyword(s):  
Aluminum Oxide ◽  
Current Density ◽  
Electrochemical Impedance ◽  
Synergistic Effects ◽  
Methanol Electrooxidation ◽  
Pt Catalyst ◽  
Thermal Method ◽  
Active Surface Area ◽  
Maximum Current Density ◽  
Maximum Current

A new type of amorphous barium aluminum oxide was synthesized using a polyol thermal method involving a mixture with Vulcan XC-72 carbon and supported with 20%Pt catalysts to enhance the activity of a methanol electrooxidation reaction (MOR). The maximum current density, electrochemically active surface area (ECSA), and electrochemical impedance spectra (EIS) of the obtained catalysts for MOR were determined. The MORs of barium aluminum oxide with different calcination temperatures and Ba and Al contact ratios were studied. The MOR of the uncalcined amorphous Ba0.5AlOx catalysts prepared with a mole ratio of 2/1 Ba/Al mixed with Vulcan XC-72 carbon and supported with 20%Pt catalyst (Pt-Ba0.5AlOx/C) was enhanced compared with that of 20%Pt-Al2O3/C and 20%Pt/C catalysts due to its obtained largest maximum current density of 3.89 mA/cm2 and the largest ECSA of 49.83 m2/g. Therefore, Pt-Ba0.5AlOx/C could provide a new pathway to achieve a sufficient electrical conductivity, and possible synergistic effects with other active components improved the catalytic activity and stability of the prepared catalyst in MOR.

scholarly journals Polarization Potential Has No Effect on Maximum Current Density Produced by Halotolerant Bioanodes

Energies ◽  
2018 ◽  
Vol 11 (3) ◽  
pp. 529 ◽  
Author(s):  
Muriel González-Muñoz ◽  
Xochitl Dominguez-Benetton ◽  
Jorge Domínguez-Maldonado ◽  
David Valdés-Lozano ◽  
Daniella Pacheco-Catalán ◽  
...  
Keyword(s):  
Current Density ◽  
Polarization Potential ◽  
Maximum Current Density ◽  
Maximum Current

Superconducting Interconnections in Future High Performance Systems

1987 ◽  
Vol 108 ◽  
Author(s):  
R. C. Frye
Keyword(s):  
Critical Current ◽  
High Speed ◽  
High Performance ◽  
Electronic Systems ◽  
Maximum Current Density ◽  
Maximum Current ◽  
High Performance Systems ◽  
Current Densities ◽  
Very High ◽  
Scaling Rule

ABSTRACTNew, high temperature superconducting materials could eventually be used for interconnections in electronic systems. Such interconnections would undoubtedly cost more to implement than conventional ones, so the most likely applications would be for complex, high-speed systems that could benefit from the performance advantages of a resistance-free interconnecting medium. The problem with conventional conductors in these systems is that the resistance of wires increases quadratically as dimensions are scaled down. The most important advantage offered by superconductors is that they are not linked to this scaling rule. Their principal limitation is the maximum current density that they will support and this determines the range of applications for which they are superior to conventional conductors. An analysis will be presented which examines the relative advantages of superconductors for different critical current densities, wire dimensions and system sizes.If their critical current densities are adequate, and if they can statisfy a number of processing criteria, then superconductors could find useful applications in a number of high performance electronic systems. The most likely applications will be those demanding very high interconnection densities. Several of these systems will be discussed.

Preparation and Hydrogen Pumping Characteristics of BaCe0.8Y0.2O3-δ Thin Film

2004 ◽  
Vol 835 ◽  
Author(s):  
T. H. Lee ◽  
B. J. Harder ◽  
C. Zuo ◽  
S. E. Dorris ◽  
U. Balachandran
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Grain Size ◽  
Current Density ◽  
Applied Voltage ◽  
Spray Deposition ◽  
High Hydrogen ◽  
Maximum Current Density ◽  
Maximum Current ◽  
Very High

ABSTRACTThin films of BaCe0.8Y0.2O3-δ (BCY) were prepared by colloidal spray deposition. Dense, crack-free BCY films having a grain size of 2–7 μm were successfully deposited on NiO/BCY substrates. Electrochemical hydrogen pumping with the BCY films showed that the maximum current density increased with temperature. The maximum current density was sensitive to the moisture in the cathode gas; the value obtained with a dry cathode gas was only half that with a wet cathode gas. A very high hydrogen-pumping current density of 3.4 A/cm2 was measured at 700°C with an applied voltage of 1.5 V.

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