Influences of Pulse Current Density on the Characteristics of Ni-W-P-CeO2-SiO2 Composite Coatings

2011 ◽  
Vol 418-420 ◽  
pp. 856-860 ◽  
Author(s):  
Rui Dong Xu ◽  
Da Cheng Zhai ◽  
Shuang Li Hu
Keyword(s):  
Chemical Composition ◽  
Current Density ◽  
Pulse Current ◽  
Composite Coatings ◽  
Average Current Density ◽  
Fine Grained ◽  
Fine Grained Structure ◽  
Average Current ◽  
S Deposition ◽  
Microhardness Tester

Square-wave double pulse current was used to electrodeposit Ni-W-P-CeO2-SiO2composite coatings in fine-grained structure on the surface of carbon steel, influences of forward pulse average current density, +Jm, in the range of 5~25A/dm2on characteristics of the composite coatings were researched, and the chemical compositionSubscript texts, deposition rate, microhardness and microstructures were evaluated by EDX, SEM and Microhardness tester. The results show that the uniform composite coatings can be obtained at +Jmof 20A/dm2, which possess higher microhardness of 735Hv. The grains sizes of the composite coatings decrease when +Jmis increased from 5A/dm2to 20A/dm2, while the reappearance of large grains structure at 25A/dm2.

Pulse Electrodepositon of Ni-W-P-CeO2-SiO2 Composite Coatings

2010 ◽  
Vol 97-101 ◽  
pp. 1389-1392 ◽  
Author(s):  
Rui Dong Xu ◽  
Jun Li Wang ◽  
Yu Zhi Zhang ◽  
Zhong Cheng Guo
Keyword(s):  
Pulse Current ◽  
Composite Coatings ◽  
Chemical Compositions ◽  
Peak Current ◽  
Wave Pulse ◽  
Fine Grained ◽  
Fine Grained Structure ◽  
Current Densities ◽  
Pulse Peak ◽  
Microhardness Tester

Square-wave pulse current was used to electrodeposit Ni-W-P-CeO2-SiO2 composite coatings. The influence of pulse on-times, off-times and peak current densities on properties of the composite coatings was researched. The microhardness, chemical compositions and microstructures were evaluated by EDX, SEM and microhardness tester. The results show that the composite coatings possessed higher microhardness and fine-grained structure. The crystal sizes of the composite coatings were found initially to decrease with the rise of pulse on-times before it started to increase with further increasing pulse on-times. Decreasing pulse off-times or increasing pulse peak current densities resulted in considerable refinement of crystal sizes.

scholarly journals The study of Zn–Co alloy coatings electrochemically deposited by pulse current

2012 ◽  
Vol 66 (5) ◽  
pp. 749-757 ◽  
Author(s):  
Jelena Bajat ◽  
Miodrag Maksimovic ◽  
Milorad Tomic ◽  
Miomir Pavlovic
Keyword(s):  
Surface Roughness ◽  
Current Efficiency ◽  
Direct Current ◽  
Current Density ◽  
Pulse Current ◽  
Pulse Plating ◽  
Cathodic Current ◽  
Average Current Density ◽  
Corrosion Stability ◽  
Average Current

The electrochemical deposition by pulse current of Zn-Co alloy coatings on steel was examined, with the aim to find out whether pulse plating could produce alloys that could offer a better corrosion protection. The influence of on-time and the average current density on the cathodic current efficiency, coating morphology, surface roughness and corrosion stability in 3% NaCl was examined. At the same Ton/Toff ratio the current efficiency was insignificantly smaller for deposition at higher average current density. It was shown that, depending on the on-time, pulse plating could produce more homogenous alloy coatings with finer morphology, as compared to deposits obtained by direct current. The surface roughness was the greatest for Zn-Co alloy coatings deposited with direct current, as compared with alloy coatings deposited with pulse current, for both examined average current densities. It was also shown that Zn-Co alloy coatings deposited by pulse current could increase the corrosion stability of Zn-Co alloy coatings on steel. Namely, alloy coatings deposited with pulse current showed higher corrosion stability, as compared with alloy coatings deposited with direct current, for almost all examined cathodic times, Ton. Alloy coatings deposited at higher average current density showed greater corrosion stability as compared with coatings deposited by pulse current at smaller average current density. It was shown that deposits obtained with pulse current and cathodic time of 10 ms had the poorest corrosion stability, for both investigated average deposition current density. Among all investigated alloy coatings the highest corrosion stability was obtained for Zn-Co alloy coatings deposited with pulsed current at higher average current density (jav = 4 A dm-2).

Preparation of Ni-ZrO2-CeO2 Nanocomposite Coatings by Pulse Electrodeposition

2013 ◽  
Vol 395-396 ◽  
pp. 174-178 ◽  
Author(s):  
Yang Yang Xu ◽  
Yu Jun Xue ◽  
Fang Yang ◽  
Chun Yang Liu ◽  
Ji Shun Li
Keyword(s):  
Current Density ◽  
Smooth Surface ◽  
Pulse Current ◽  
Nanocomposite Coating ◽  
Pulse Electrodeposition ◽  
Nanocomposite Coatings ◽  
Duty Ratio ◽  
Average Current Density ◽  
Average Current ◽  
Surface Morphologies

Ni-ZrO2-CeO2nanocomposite coatings were prepared by pulse electrodeposition. The effect additions of ZrO2and CeO2nanoparticles, average current density, duty ratio and frequency of pulse current on nanoparticle contents of Ni-ZrO2-CeO2nanocomposites were studied. The surface morphologies and microhardness of different nanocomposite coatings (Ni-ZrO2, Ni-CeO2, Ni-ZrO2-CeO2) were analyzed. The results show that, with the average current density, duty ratio and frequency increased, the nanoparticle contents increased at first and then decreased. Compared with Ni-ZrO2and Ni-CeO2, the surface morphology of Ni-ZrO2-CeO2nanocomposite coating showed better smooth surface and more compact microstructure, the microhardness was also higher.

Effect of Pulse Electrodeposition Parameters on Microhardness of Ni-ZrO2-CeO2 Nanocomposite Coating

2014 ◽  
Vol 1049-1050 ◽  
pp. 31-34
Author(s):  
Shuang Shuang Liu ◽  
Yu Jun Xue ◽  
Yang Yang Xu ◽  
Ji Shun Li
Keyword(s):  
Composite Coating ◽  
Current Density ◽  
Pulse Current ◽  
Pulse Frequency ◽  
Nanocomposite Coating ◽  
Pulse Electrodeposition ◽  
Duty Ratio ◽  
Positive Duty ◽  
Average Current Density ◽  
Average Current

Ni-ZrO2-CeO2 nanocomposite coating was prepared by pulse electrodeposition. The effect of addition of ZrO2 and CeO2 nanoparticles, average current density, duty cycle and pulse current on microhardness of Ni-ZrO2-CeO2 nanocomposites were studied. The results show that microhardness of nanocomposite is increased at first and then decreased with the increasing additive amounts of two kinds of nanoparticles. With increasing reverse the average current density, the microhardness of the composite coating increases. Also, the microhardness of nanocomposite fall with the increasing of pulse frequency. With the positive duty ratio increasing, the microhardness of the composite coating increase at first and then decreased, but with the increasing of the reverse duty ratio, the microhardness of nanocomposite coating is gradually decreased.

scholarly journals Morphology, Structure and Mechanical Properties of Copper Coatings Electrodeposited by Pulsating Current (PC) Regime on Si(111)

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 488 ◽  
Author(s):  
Ivana O. Mladenović ◽  
Jelena S. Lamovec ◽  
Dana G. Vasiljević Radović ◽  
Rastko Vasilić ◽  
Vesna J. Radojević ◽  
...  
Keyword(s):  
Current Density ◽  
Diffusion Control ◽  
Copper Electrodeposition ◽  
Average Current Density ◽  
Fine Grained ◽  
Average Current ◽  
Hardness Model ◽  
Xrd Techniques ◽  
Composite Hardness ◽  
Pulsating Current

Copper electrodeposition on (111)-oriented Si substrate was performed by the pulsating current (PC) regime at various average current densities in the range of 15–70 mA·cm−2, obtained by varying either the frequency (30, 50, 80 and 100 Hz for the current density amplitude of 100 mA·cm−2) or the current density amplitude (120 and 140 mA·cm−2 at 100 Hz). The produced Cu coatings were examined by SEM, AFM and XRD techniques. The morphology of the coatings changed from those with large grains to fine-grained and globular, while the crystal structure changed from the strong (220) to the strong (111) preferred orientation by increasing the average current density. The mechanical characteristics of coatings were examined using Vickers micro-indentation tests, applying the Chicot–Lesage (C–L) composite hardness model for the analysis of microhardness. The maximum microhardness was obtained for the Cu coating produced at an average current density of 50 mA·cm−2, with a current density amplitude of 100 mA·cm−2 and a frequency of 100 Hz. This copper coating was fine-grained and showed the smallest roughness in relation to the other coatings, and it was obtained in the mixed activation–diffusion control between the end of the effect of the activation control and the beginning of the dominant effect of diffusion control.

Technology on Ni-ZrO2-CeO2 Nanocomposites by Pulse Electroforming in an Ultrasonic Field

2013 ◽  
Vol 579-580 ◽  
pp. 138-143
Author(s):  
Yang Yang Xu ◽  
Yu Jun Xue ◽  
Ji Shun Li ◽  
Yi Liu ◽  
Fang Yang
Keyword(s):  
Surface Morphology ◽  
Current Density ◽  
Pulse Current ◽  
Ultrasonic Field ◽  
Double Pulse ◽  
Duty Ratio ◽  
Positive Duty ◽  
Average Current Density ◽  
Average Current ◽  
Positive Frequency

Ni-ZrO2-CeO2 nanocomposites were prepared by double-pulse current in an ultrasonic field. The effect of average current density, duty ratio and frequency of double-pulse current on nanoparticles content of Ni-ZrO2-CeO2 nanocomposites was studied. Meanwhile, surface morphology and microhardness of nanocomposites were analyzed. The results show that, with the positive average current density, positive duty ratio and positive frequency increased, the nanoparticles contents increased at first and then decreased. On the contrary, it reduced while reverse average current density, reverse duty ratio and reverse frequency were increasing. Compared with Ni-ZrO2-CeO2 prepared by direct current and monopulse current, grain of Ni-ZrO2-CeO2 nanocomposite prepared by double-pulse current is finer, the microhardness is also higher.

scholarly journals Application of the Composite Hardness Models in the Analysis of Mechanical Characteristics of Electrolytically Deposited Copper Coatings: The Effect of the Type of Substrate

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 111
Author(s):  
Ivana O. Mladenović ◽  
Nebojša D. Nikolić ◽  
Jelena S. Lamovec ◽  
Dana Vasiljević-Radović ◽  
Vesna Radojević
Keyword(s):  
Mechanical Characteristics ◽  
Dislocation Creep ◽  
Average Current Density ◽  
Fine Grained ◽  
Copper Coatings ◽  
Electrochemically Deposited ◽  
Composite Models ◽  
Average Current ◽  
Composite Hardness ◽  
Coating Hardness

The mechanical characteristics of electrochemically deposited copper coatings have been examined by application of two hardness composite models: the Chicot-Lesage (C-L) and the Cheng-Gao (C-G) models. The 10, 20, 40 and 60 µm thick fine-grained Cu coatings were electrodeposited on the brass by the regime of pulsating current (PC) at an average current density of 50 mA cm−2, and were characterized by scanning electron (SEM), atomic force (AFM) and optical (OM) microscopes. By application of the C-L model we determined a limiting relative indentation depth (RID) value that separates the area of the coating hardness from that with a strong effect of the substrate on the measured composite hardness. The coating hardness values in the 0.9418–1.1399 GPa range, obtained by the C-G model, confirmed the assumption that the Cu coatings on the brass belongs to the “soft film on hard substrate” composite hardness system. The obtained stress exponents in the 4.35–7.69 range at an applied load of 0.49 N indicated that the dominant creep mechanism is the dislocation creep and the dislocation climb. The obtained mechanical characteristics were compared with those recently obtained on the Si(111) substrate, and the effects of substrate characteristics such as hardness and roughness on the mechanical characteristics of the electrodeposited Cu coatings were discussed and explained.

The efficient use of stabilizing materials in superconducting solenoids

1969 ◽  
Vol 47 (13) ◽  
pp. 1401-1407 ◽  
Author(s):  
Richard Stevenson
Keyword(s):  
Current Density ◽  
Transient Heat Conduction ◽  
Point Of View ◽  
Average Current Density ◽  
Initial Current ◽  
Current Sharing ◽  
Purity Aluminium ◽  
High Purity Aluminium ◽  
Average Current ◽  
Composite Conductor

The problem of stability of superconducting solenoids is considered from a thermal point of view. The transient heat conduction equation for a superconducting tape clad with normal material and operated in a current sharing mode is studied, and a solution for the temperature distribution is obtained. The composite conductor is considered stable if its final temperature in the current sharing mode corresponds to the critical temperature for the initial current density in the superconductor. Using this criterion, the operating point of the superconductor and its stabilizing cladding thickness can be chosen to give a maximum average current density in the composite conductor at any field. Calculations are given for Nb3Sn tape clad with OFHC copper and with high purity aluminium.

Study on the Influence of Electrode Collocation to Electric Field Characteristic of ESP

2014 ◽  
Vol 875-877 ◽  
pp. 1683-1686
Author(s):  
Cheng Liang Jia ◽  
You Shan Sun ◽  
Chao Huang ◽  
Wan Peng Zhang ◽  
Fang Chen
Keyword(s):  
Electric Field ◽  
Current Density ◽  
Surface Current ◽  
Electrode Configuration ◽  
Electrode Gap ◽  
Average Current Density ◽  
Surface Current Density ◽  
Discharge Electrode ◽  
Field Characteristic ◽  
Average Current

A laboratory-scale ESP with new electrode configuration was established to investigate the electric field characteristic. Eight teeth prick line and prick plate with the length of 20mm were employed as discharge electrodes, respectively. The effects of discharge electrode type and electrode gap on V-I characteristic and surface current density were studied. The results showed that the optimum electrode gaps were 350-400mm for eight teeth line and 300-350mm for prick plate, which could obtained higher average current density and lower variance.

Current Distribution in a Polymer Electrolyte Membrane Fuel Cell Under Flooding Conditions

2009 ◽  
Author(s):  
A. Jamekhorshid ◽  
G. Karimi ◽  
X. Li
Keyword(s):  
Fuel Cell ◽  
Polymer Electrolyte ◽  
Current Distribution ◽  
Current Density ◽  
Polymer Electrolyte Membrane ◽  
Operating Conditions ◽  
Average Current Density ◽  
Electrolyte Membrane ◽  
Wide Range ◽  
Average Current

Non-uniform current distribution in polymer electrolyte membrane fuel cells results in local over-heating, accelerated ageing, and lower power output than expected. This issue is very critical when fuel cell experiences water flooding. In this work, the performance of a PEM fuel cell is investigated under cathode flooding conditions. A partially flooded GDL model is proposed to study local current density distributions along flow fields over a wide range of cell operating conditions. The model results show as cathode inlet humidity and/or cell pressure increase the average current density for the unflooded portions of the cell increases but the system becomes more sensitive to flooding. Operating the cell at higher temperatures would lead to higher average current densities and the chance of system being flooded is reduced. In addition, higher cathode stoichiometries prevent system flooding but the average current density remains almost constant.

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