scholarly journals Excellent Properties of Ni-15 wt.% W Alloy Electrodeposited from a Low-Temperature Pyrophosphate System

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1262
Author(s):  
Changwei Su ◽  
Zhaoyao Sa ◽  
Yangyang Liu ◽  
Linfu Zhao ◽  
Fengjing Wu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Low Temperature ◽  
Current Density ◽  
High Current ◽  
Nacl Solution ◽  
Applied Current ◽  
Suitable Candidate ◽  
Applied Current Density ◽  
Microhardness Tester

Electrodeposited Ni-W alloy coatings are considered to be one of the most suitable candidate coatings to replace carcinogenic hexavalent chromium coatings. In this work, Ni-W alloys are electrodeposited from pyrophosphate baths containing different concentrations of Na2WO4 2H2O (CW) at 40 °C. Both CW and the applied current density can affect the W content in the coatings. The effect of CW becomes weaker with the increased current density. The Ni-W alloys with 15 ± 5 wt.% W (Ni-15 wt.% W) are obtained from the bath containing 40 g L−1 CW at a high current of 8 A dm−2. The microhardness, corrosion resistance and hydrogen evolution reaction (HER) are measured with a microhardness tester and an electrochemical workstation. The modified properties are studied by heat treatment from 200 to 700 °C. The highest microhardness of 895.62 HV and the better HER property is presented after heat treatment at 400 °C, while the best corrosion resistance in 3.5 wt.% NaCl solution appears at 600 °C.

scholarly journals Effect of Applied Current Density of Plasma Electrolytic Oxidation Process on Corrosion Resistance of AZ31 Magnesium Alloy

2019 ◽  
Vol 21 (2) ◽  
pp. 32-36 ◽  
Author(s):  
Daniel Kajanek ◽  
Branislav Hadzima ◽  
Matej Brezina ◽  
Martina Jackova
Keyword(s):  
Corrosion Resistance ◽  
Magnesium Alloy ◽  
Current Density ◽  
Plasma Electrolytic Oxidation ◽  
Az31 Magnesium Alloy ◽  
Applied Current ◽  
Applied Current Density ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Peo Coatings

Impact of applied current density during the plasma electrolytic oxidation (PEO) process on corrosion resistance of AZ31 magnesium alloy was studied. The PEO coatings were prepared using four different current densities with values of 0.025 A/cm2, 0.05 A/cm2, 0.1 A/cm2 and 0.15 A/cm2 in electrolyte consisting of 10 g/l Na 3PO4.12H2O and 1 g/l KOH. Morphology and chemical composition of the coatings was examined using the scanning electron microscopy and EDS analysis respectively. Electrochemical characteristics of ground and coated samples were measured by means of electrochemical impedance spectroscopy (EIS) in 0.1M NaCl solution. Obtained data in form of Nyquist diagrams were analysed by equivalent circuit method. Results of experiments showed that value of applied current density had significant effect on protective performance of the PEO coatings prepared on AZ31 magnesium alloy surface.

Effect of Equal Channel Angular Pressing and Annealing on Corrosion Resistance of Al-Cu Alloy

2013 ◽  
Vol 803 ◽  
pp. 226-229
Author(s):  
Da Ran Fang ◽  
Chun Liu ◽  
Feng Fang Liu
Keyword(s):  
Corrosion Resistance ◽  
Low Temperature ◽  
Equal Channel Angular Pressing ◽  
Annealing Treatment ◽  
Coarse Grained ◽  
Nacl Solution ◽  
Angular Pressing ◽  
Cu Alloy ◽  
Low Temperature Annealing ◽  
Ultrafine Grained

Al-3.9wt.%Cu alloy was subjected to equal channel angular pressing (ECAP) and subsequent low temperature annealing treatment, and the corrosion resistance of the samples was investigated by potentiodynamic polarization measurements in 3.5% NaCl solution. The results show that the corrosion rate of the ultrafine-grained alloy increases, in comparison with the coarse-grained alloy. Meanwhile, it is noted that the corrosion resistance of the alloy subjected to ECAP can be improved by relief annealing.

scholarly journals Methiocarb Degradation by Electro-Fenton: Ecotoxicological Evaluation

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5893
Author(s):  
Faléstine Souiad ◽  
Ana Sofia Rodrigues ◽  
Ana Lopes ◽  
Lurdes Ciríaco ◽  
Maria José Pacheco ◽  
...  
Keyword(s):  
Current Density ◽  
Iron Concentration ◽  
Model Organism ◽  
Anodic Current Density ◽  
Applied Current ◽  
Boron Doped Diamond ◽  
Applied Current Density ◽  
Toxic Units ◽  
Boron Doped ◽  
Ecotoxicological Evaluation

This paper studies the degradation of methiocarb, a highly hazardous pesticide found in waters and wastewaters, through an electro-Fenton process, using a boron-doped diamond anode and a carbon felt cathode; and evaluates its potential to reduce toxicity towards the model organism Daphnia magna. The influence of applied current density and type and concentration of added iron source, Fe2(SO4)3·5H2O or FeCl3·6H2O, is assessed in the degradation experiments of methiocarb aqueous solutions. The experimental results show that electro-Fenton can be successfully used to degrade methiocarb and to reduce its high toxicity towards D. magna. Total methiocarb removal is achieved at the applied electric charge of 90 C, and a 450× reduction in the acute toxicity towards D. magna, on average, from approximately 900 toxic units to 2 toxic units, is observed at the end of the experiments. No significant differences are found between the two iron sources studied. At the lowest applied anodic current density, 12.5 A m−2, an increase in iron concentration led to lower methiocarb removal rates, but the opposite is found at the highest applied current densities. The highest organic carbon removal is obtained at the lowest applied current density and added iron concentration.

Electrodeposition of Polyhedral Copper Crystals on Porous Silicon

2011 ◽  
Vol 181-182 ◽  
pp. 434-438
Author(s):  
Ming Meng ◽  
Yuan Ming Huang
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Copper Chloride ◽  
Applied Current ◽  
Sem Images ◽  
Copper Crystal ◽  
Applied Current Density ◽  
Current Density Range ◽  
Tentative Explanation ◽  
Copper Crystals

Electrochemical deposition of copper from copper chloride aqueous electrolyte on porous silicon (PS) substrate was investigated in the current density range of 5 mA/cm2to 35 mA/cm2. Scanning electron microscopy (SEM) was utilized to characterize the surface morphology of as-electrodeposited PS. SEM images illustrate that the applied current density has a profound influence on the shape of copper crystal electrodeposited on the top surface of PS films. When the applied current density was fixed at 5mA/cm2, most of the copper crystals are in the shape of cube along with a small number of cuboid-shape. With the increasing current density, cuboid-shaped copper crystals gradually vanished. When the current density is up to the 35mA/cm2, we surprisingly observe that the cube shape predominates simultaneously with the emergence of truncated tetrahedron. A tentative explanation for the growth mechanism of copper crystal having various shapes is explored.

Corrosion Characteristics of Surface-Modified DET Magnesium Powders

2004 ◽  
Vol 449-452 ◽  
pp. 369-372
Author(s):  
W.S. Chung ◽  
W.Y. Yoon ◽  
Kwang Jin Kim
Keyword(s):  
Corrosion Resistance ◽  
Surface Layer ◽  
Current Density ◽  
Nacl Solution ◽  
Composition Distribution ◽  
Passive Behavior ◽  
Modified Surfaces ◽  
Modified Surface ◽  
Surface Modified ◽  
Modified Surface Layer

Magnesium powders having inactive surface layer have been processed easily and intentionally by DET under fluoride, chromate, and bromide salt. The modified surfaces play an important role in preventing contact with active environments to improve corrosion resistance of Magnesium powders; the image of the surface modified powders was observed using SEM. The composition distribution and characteristics was determined and analyzed by using XRD, XPS, and EIS. Compared with bare Magnesium, the Magnesium having chromate modified surface layer showed a more passive behavior such as smaller current density and nobler potential in 4wt% NaCl solution.

Effects of Heat Treatment and Alloying of Spheroidal Graphite Cast Iron on Corrosion Resistance in Aqueous Environment

2004 ◽  
Vol 449-452 ◽  
pp. 533-536
Author(s):  
M. Aoyama ◽  
K. Tahashi ◽  
K. Matsuno
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Cast Iron ◽  
Current Density ◽  
Electrode Potential ◽  
Corrosion Current ◽  
Spheroidal Graphite ◽  
Spheroidal Graphite Cast Iron ◽  
Graphite Cast Iron ◽  
The Matrix

The present study examined the effects of heat treatment and the addition of Cu-Ni alloy on the corrosion resistance of the matrix of spheroidal graphite cast iron in aqueous environments. Test materials of white cast iron and carbon steel were used for comparison with spheroidal graphite cast iron. The alloy spheroidal graphite cast iron that added Cu and Ni was prepared. The spheroidal graphite cast iron was subjected to three kinds of heat treatment to adjust the matrix: annealing, oil quenching, and austemper heat treatment. In electrochemical tests, measurements of corrosion electrode potential and cathode and anode polarization were used. The following was clarified from the relationship between the electrode potential and current density of each of the materials in each of the solution. The alloy spheroidal graphite cast iron had a high corrosion electrode potential owing to the addition of Cu-Ni, and tended to have a low corrosion current density. This demonstrates that in any of the materials having a matrix adjusted by heat treatment, the addition of Cu-Ni increased the corrosion resistance. The corrosion current density was highest in a sulfuric acid environment.

Electroless Nickel Plating on Copper Foil

2014 ◽  
Vol 926-930 ◽  
pp. 103-107
Author(s):  
Zuo Qin Tang ◽  
Su Rong Hu ◽  
Yin Chun Chao
Keyword(s):  
Corrosion Resistance ◽  
Potentiodynamic Polarization ◽  
Copper Foil ◽  
Electroless Nickel ◽  
Electroless Nickel Plating ◽  
Nickel Plating ◽  
Nacl Solution ◽  
Tribological Behaviour ◽  
Microhardness Tester

A pre-cleaning and an electroless nickel plating (EN-HP) were applied to copper foil to improve its tribological behaviour and corrosion resistance. The coating porosity was measured by the corrodkote, tribological behaviour was measured with microhardness tester and a CSM ball-on-disk tribometer, corrosion resistance was measured by potentiodynamic polarization in 3.5 wt.% NaCl solution. Matte nickel plating (mNi) and moderate compact Ni–P coating (EN-MP) were made as comparisons to EN-HP in those tests. By deposition of EN-HP, both coating porosity and tribological behaviour are greatly improved compared to mNi, and the corrosion resistance is distinctly ameliorated to the comparisons. Above research demonstrates that the copper foil with EN-HP coating is good underlay in assemblage of machine.

Investigation on the conductivity-dependent performance in low voltage cathodoluminescence

2015 ◽  
Vol 17 (15) ◽  
pp. 9936-9941 ◽  
Author(s):  
Chunyu Shang ◽  
Jinxian Zhao ◽  
Xiuqin Wang ◽  
Hongyang Xia ◽  
Hui Kang
Keyword(s):  
Current Density ◽  
Low Voltage ◽  
Generation Rate ◽  
Applied Current ◽  
Electron Hole ◽  
Phosphor Layer ◽  
Applied Current Density ◽  
Hole Generation

With the increase of applied current density in low voltage cathodoluminescence, the exciting power tends to saturate, causing the saturation of electron–hole generation rate in the phosphor layer.

Study of Forward Voltage Drift in Diffused SiC PiN Diodes Doped by Al or B

2005 ◽  
Vol 483-485 ◽  
pp. 989-992 ◽  
Author(s):  
S.I. Maximenko ◽  
Stanislav I. Soloviev ◽  
A.E. Grekov ◽  
A.V. Bolotnikov ◽  
Ying Gao ◽  
...  
Keyword(s):  
Current Density ◽  
Room Temperature ◽  
Stacking Faults ◽  
Applied Current ◽  
Forward Voltage ◽  
Pin Diodes ◽  
Applied Current Density ◽  
Voltage Drift ◽  
Significant Change ◽  
Degradation Testing

The degradation of diffused SiC PIN diodes during forward-biased operation was studied by first fabricating PIN diodes by diffusion of aluminum or boron into 4H-SiC substrates with n-type 10-15 µm thick epilayers doped by nitrogen up to 5x1015cm-3. The formed diodes were subjected to degradation testing under an applied current density of 200A/cm2 at room temperature. The majority of the Al diffused diodes demonstrated a voltage drift, ΔVf, of more than 2 V, while B-doped diodes showed no significant change in forward voltage. The EBIC mode of SEM was employed to monitor nucleation and expansion of stacking faults.

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