Effect Of Peak Current Density Research Articles

Effect of Peak Current Density on Tensile Properties of AZ31B Magnesium Alloy.

An investigation into the effects, including the athermal effect, of a pulsed current on AZ31B magnesium alloy was carried out. Different peak current densities were applied at the same temperature under uniaxial tensile testing. The results indicate that the stress reduction caused by the increasing peak current density is independent of temperature. The strain hardening coefficient also shows a similar trend. The fracture strain shows the optimum value due to the current crowding effect.

Effect of Peak Current Density on Inner-wall Deposition of Ti Films by High-power Impulse Magnetron Sputtering

Effect of Peak Current Density on Inner-wall Deposition of Ti Films by High-power Impulse Magnetron Sputtering

Effect of electropulsing on springback during V-bending of Ti-6Al-4V titanium alloy sheet

Effect of frequency and peak current density of electropulsing on springback behaviors of Ti-6Al-4V titanium alloy was investigated during electrically assisted V-bending tests. The experiments were carried out by controlling variable parameters with a frequency of 0–450 Hz and peak current density of 0–62.5 A/mm2. The results show that springback angle and V-bending load value decrease with increasing frequency and peak current density. Springback can almost be eliminated at 450 Hz and 43.1 A/mm2. Based on neutral layer offset and microstructure analysis, it demonstrates that the reductions of neutral layer radius, bending moment, and residual stress are responsible for the springback reduction. In addition, the refined β phase particles, dissolution of clustered β phase, the reduction of β particle spacing at outer layer, and enhancement of β particle spacing at inner layer contribute to the balance of tensile and compression residual stress, contributing to springback reduction. Effect of peak current densities on the springback behavior under similar RMS current density was carried out and it was found that athermal effect could promote the dislocation motion and unraveling of dislocation pile-ups, further promoting to the springback reduction.

Effect of DC pulsed-current on deformation behavior of magnesium alloy thin sheets

A uniaxial tensile test was developed to investigate material deformation behavior under DC pulsed current load. Duty cycle was kept low to provide wide gap between peak current density and average current density. With average current density preserved at low value, the Joule heating effect can be minimized thus keeping temperature low. Tensile tests were carried out by changing peak current density value while keeping temperature near 40 ˚C. That approach can further distinguish effect of Joule Heating. In this research, it was observed that the effect of peak current density was not present.

Synergistic effect of peak current density and nature of surfactant on microstructure, mechanical and electrochemical properties of pulsed electrodeposited Ni-Co-SiC nanocomposites

Ni-Co-nano SiC composite coatings were electrodeposited from a modified Watt's bath containing CTAB or SDS by pulse electrodeposition at four different peak current densities. The synergistic effect of the pulse peak current density and surfactant results in distinct morphological characteristics (characterized by SEM & TEM) and structural properties (characterized by XRD) producing nanocomposites with different mechanical (microhardness testing and nanoindentation testing) and electrochemical properties which can be traced to a multitude of factors such as nano SiC content and distribution, Cobalt content, grain refinement and texture. CTAB acts as a better dispersing agent for stabilising SiC nanoparticles compared to SDS, producing non-agglomerated SiC nanoparticles with a narrow size distribution. Increasing current density changes microstructure from spherical aggregates of polyhedral crystals (at 0.2 Acm−2) to uniform globular morphology (at 0.3 Acm−2) and finally to spherical aggregates (at 0.4 and 0.5 Acm−2), decreases cobalt content, increases SiC incorporation (up to a peak current density of 0.4Acm−2) and decreases coating thickness. Peak current density of the pulse electrodeposition is a vital factor in determining the crystallite size whereas both peak current density and nature of surfactant used are important factors in determining the texture. Electrodeposits with CTAB as surfactant provided higher values of hardness compared to SDS as surfactant, with C3 having the maximum hardness of 582 VHN because of nanosized grains and uniform dispersion of nano sized SiC. Nanocomposite electrodeposited using SDS as surfactant at a peak current density of 0.3Acm−2 has the highest corrosion resistance with a corrosion current density of 0.47 μAcm−2 and polarization resistance of 120.37 KOhm cm−2 in 3.5 wt% NaCl solution.

Effects of peak current density on the structure and property of PbO2–CeO2 nanocomposite electrodes prepared by pulse electrodeposition

PbO2–CeO2 nanocomposite electrodes were prepared by pulse electrodeposition method in the lead nitrate solution containing CeO2 nanoparticles with different peak current density. The content of CeO2 nanoparticles in the electrodes increase with the increase of peak current density. The effects of peak current density on the morphology and structure of PbO2–CeO2 nanocomposite electrodes were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The SEM and XRD results show that the increase of peak current density can make the morphology finer and more compact, and the crystal size decreases with the increase of peak current density. The oxygen evolution overpotential and stability of PbO2–CeO2 nanocomposite electrodes enhance with the increase of peak current density. The electrocatalytic property of PbO2–CeO2 nanocomposite electrodes was examined for the electrochemical oxidation of rhodamine B (RhB). The results show that the RhB removal efficiency on PbO2–CeO2 nanocomposite electrodes increase with the increase of peak current density, which can be attributed to the higher oxygen evolution overpotential and CeO2 content in the composite electrodes.

Three-dimensional Sn rich Cu6Sn5 negative electrodes for Li ion batteries

Three-dimensional Sn rich Cu6Sn5 electrodes were fabricated by the pulse electrodeposition process on a porous nickel foam substrate to improve discharge capacity and cycleability of the SnCu alloy negative electrodes for Li-ion batteries. It was aimed to investigate the effect of peak current density on the structure and electrochemical performance of the Sn rich Cu6Sn5 electrodes. The morphology and the structures of the SnCu alloy electrodes were characterized by scanning electron microscopy (SEM). X-ray diffraction (XRD) analyses was also performed to investigate the structure of electrodeposited SnCu based electrodes. The electrochemical features of the electrodes were investigated by charge/discharge tests, cyclic voltammetry experiments and the ac impedance technique. Results showed that morphology of the electrodes exhibited a strong effect on the electrochemical performances and the best electrochemical performances were achieved in the alloy electrodes, which has dendritic like structure obtained using high peak current density.

Influence of Substrate, Additives, and Pulse Parameters on Electrodeposition of Gold Nanoparticles from Potassium Dicyanoaurate

Gold nanoparticles (AuNPs) of less than 50 nm diameter were electrodeposited from cyanide solution by pulsating electric current on modified copper and indium tin oxide (ITO) films coated on glass. Morphology, size, and composition of the deposited AuNPs were studied by X-ray photoelectron spectroscopy, atomic force microscopy, and field emission scanning electron microscopy. Effects of peak current density, pulse frequency, potassium iodide and cysteine on grain size, and morphology of the AuNPs were determined. Experiments showed that cathode current efficiency increases with the pulse frequency and the iodide ion. Size of the AuNPs increased with the current density. The number of nucleation sites was larger on ITO than on Cu layer; while the average diameter of the crystallites on ITO was smaller than on Cu layer.

Double Buffering Effect on the Electrochemical Behavior of Pulse Electro co-deposited Sn-Ni/MWCNT Nanocomposite Electrodes for Lithium-ion Batteries

Tin–Nickel/multiwalled carbon nanotube (MWCNT) composite plating was performed using a pyrophosphate bath. To reduce irreversible capacity and improve cycle performance of tin electrodes, Sn–Ni/MWCNT nanocomposite electrodes were prepared with different peak current density by pulse electrodeposition method using copper substrate as current collector. The effects of peak current density on the surface morphology, microstructure and electrochemical properties were investigated. Produced Composites were characterized by scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS).X-ray diffraction (XRD) analysis was carried out to investigate structure of Sn-Ni/MWCNT composites. The electrochemical performances of Sn-Ni/MWCNT composite electrodes have been investigated by charge/discharge tests, cyclic voltammetry experiments and the ac impedance spectroscopy (EIS). The peak current density was shown to be a crucial factor to improve Sn-Ni/MWCNT composite anodes for cycleability and reversible capacity.

Pulse electrodeposition and characterization of nano Ni–W alloy deposits

Pulse plating was employed to obtain Ni–W alloy nanodeposits from ammonical citrate bath. Effects of peak current density, pH, tungstate ion concentration and temperature on the cathodic current efficiency were studied. Ni-32.8 weight (wt)% of W alloy coating was obtained using optimized bath composition. Ni–W solid solution was found in the alloy deposit. Surface morphology studies revealed that the alloy surface was covered by long needle like crystals. XRD patterns of the electrodeposits showed only fcc (nickel) peaks. The hardness of the deposits obeyed Hall–Petch relation. Electrochemical polarization studies revealed that the corrosion potentials of nickel became nobler with W addition and corrosion current density values decreased. Electrochemical impedance studies found that, the increased charge transfer resistances suggesting decreased corrosion current density values. The capacitance values of the double layer decreased with W additions.

Effect of peak current density on the mechanical and electrical properties of copper/polymide fabricated by a pulsed electrodeposition process

Copper (Cu) was deposited on a polyimide via pulsed electrodeposition for use as a conduction layer in flexible copper clad laminates. The influence of the peak current density on the mechanical hardness and electrical resistivity of the Cu films was investigated. In the fabrication process, electroless deposition was first employed to create a Cu seed layer on the polyimide. A Cu film was subsequently electro-deposited using a square wave pulse with different peak current densities. As the peak current density was increased from 1.5 to 4.0 A/dm 2, the grain size and degree of (220) preferred orientation decreased, while the hardness and electrical resistivity increased from 0.75 to 1.19 GPa and from 17.00 to 26.26 nΩm, respectively. Such changes were believed to be due to grain refinement. The relationship between grain size and resistivity was correlated with the Mayadas and Shatzkes’s model.

Effects of Direct Current and Pulse Electrodeposition Parameters on the Properties of Nano Cobalt Coatings

The aim of this study was to investigate the effects of direct current (DC) and pulse current (PC) parameters on the properties of cobalt (Co) coatings electrodeposited from a chloride acidic bath. The effects of peak current density, frequency and duty cycle on the surface morphology, crystal size, thickness, current efficiency, and preferred orientation of the deposits were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The experimental thickness of the deposit was lower for pulse plating compared to that of DC plating. The current efficiency was comparatively higher for pulse plating. Less porosity and fine grains were formed by pulse plating. From XRD analysis, the calculated grain sizes of nano and micro Co coatings were around 65nm and 430nm, respectively. The results showed that, with an increase in duty cycle, grain sizes would increase, too. As pulse frequency was increased to 50Hz, grain sizes would also decrease. However, at higher frequencies, grain sizes would increase again.

Effects of peak current density on the mechanical properties of nanocrystalline Ni–Co alloys produced by pulse electrodeposition

Cobalt content, grain size, microhardness and tensile strength of nanocrystalline Ni–Co deposits produced from a solution containing saccharin and cobalt sulfate at constant electrodeposition conditions (pulse on-time T on at 1 ms and pulse off-time T off at 15 ms) but varying the peak current density J p were investigated. It is found that an increase in J p makes the deposit Co content lower, colony-like morphology more obvious, grain size smaller, and hardness and tensile strength higher. All of the facts are believed to result from the higher overpotential and nucleation rates caused by the J p increase. But its further increase could lead to reduction in the hardness and tensile strength. Peak current densities in the range of 100–120 A dm −2 are recommended for the preparation of nanostructured Ni–Co alloy deposits with grain sizes in the range of 15–20 nm, containing 7–8% Co, possessing hardness of 590–600 kg mm −2 and tensile strength of 1180–1200 MPa—significantly higher than the strength of pure nickel deposit which is produced by the similar method and gets similar grain size.