Mechanism of Silver Nanoparticles Deposition by Electrolysis and Electroless Methods on a Graphite Substrate

This study shows a silver electrodeposition model (EDM) on a graphite ‎substrate. The electrolyte was a 0.01 M solution of pure silver and chromium nitrate using an ‎electrolyzing cell. EDC with current density up to 20 mA/cm2 and 15 mV and pulse current were studied. Results revealed that silver deposited at a ‎rate of 0.515 mg/cm2/min with 12 mA /cm2 that decreases to 0.21 and 0.16 mg/cm2.min ‎with the decrease of current density to 6 and 5 mA/cm2 respectively. The model postulates that ‎silver ions (a) were first hydrated before diffusing (b) from the solution bulk to ‎the cathode vicinity, the next step (c) involved the chemical adsorption of these ions on certain ‎accessible sites of the graphite substrate (anode), the discharged entities (d) adhere to the graphite ‎surface by Van der Vales force. Silver ions are deposited because the ‎discharge potential of silver is low (0.38 mV) as compared to other metal ions like chromium (0.82 mV). Pulse ‎current controls silver deposition due to flexibility in controlling steps (a) - (c) of the ‎deposition mechanisms.

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Bimetallic Core–Shell Nanoparticles of Gold and Silver via Bioinspired Polydopamine Layer as Surface-Enhanced Raman Spectroscopy (SERS) Platform

Nanomaterials ◽

10.3390/nano10040688 ◽

2020 ◽

Vol 10 (4) ◽

pp. 688 ◽

Cited By ~ 4

Author(s):

Asli Yilmaz ◽

Mehmet Yilmaz

Keyword(s):

Raman Spectroscopy ◽

Low Cost ◽

Silver Ions ◽

Surface Enhanced Raman Spectroscopy ◽

Core Shell ◽

Silver Deposition ◽

Shell Nanoparticles ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Core Shell Nanoparticles

Despite numerous attempts to fabricate the core–shell nanoparticles, novel, simple, and low-cost approaches are still required to produce these efficient nanosystems. In this study, we propose the synthesis of bimetallic core–shell nanoparticles of gold (AuNP) and silver (AgNP) nanostructures via a bioinspired polydopamine (PDOP) layer and their employment as a surface-enhanced Raman spectroscopy (SERS) platform. Herein, the PDOP layer was used as an interface between nanostructures as well as stabilizing and reducing agents for the deposition of silver ions onto the AuNPs. UV-vis absorption spectra and electron microscope images confirmed the deposition of the silver ions and the formation of core–shell nanoparticles. SERS activity tests indicated that both the PDOP thickness and silver deposition time are the dominant parameters that determine the SERS performances of the proposed core–shell system. In comparison to bare AuNPs, more than three times higher SERS signal intensity was obtained with an enhancement factor of 3.5 × 105.

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

Hemijska industrija ◽

10.2298/hemind111215035b ◽

2012 ◽

Vol 66 (5) ◽

pp. 749-757 ◽

Cited By ~ 1

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).

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Electrodeposition process and composition of Zn-Cr alloy coatings

Inżynieria Powierzchni ◽

10.5604/01.3001.0012.2088 ◽

2018 ◽

Vol 23 (2) ◽

pp. 3-10

Author(s):

Ewa Osuchowska ◽

Zofia Buczko ◽

Klaudia Olkowicz

Keyword(s):

Surface Morphology ◽

Current Efficiency ◽

Direct Current ◽

Current Density ◽

Pulse Current ◽

Electrodeposition Process ◽

Cr Content ◽

Zinc Coatings ◽

Deposition Current Density

In the present work, the electrodeposition process of Zn-Cr alloy coatings under the conditions of direct and pulse current was discussed. Changes in the Cr content in the obtained alloy coatings, current efficiency of the process, surface morphology, structure and microhardness as a function of chromium(III) concentration in the bath to deposition, current density (direct and pulse) and solution mixing were determined. Surface morphology, structure and hardness of the obtained coatings were investigated. The Zn-Cr alloy coatings of good quality contained up to 0.25 %Cr (for direct current) and up to 9% Cr (for pulse current). The tested Zn-Cr alloy coatings obtained under pulse current conditions showed higher microhardness than the Zn-Cr coatings obtained under direct current conditions and than zinc coatings.

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Complexing agent study for environmentally friendly silver electrodeposition(ii): electrochemical behavior of silver complex

RSC Advances ◽

10.1039/c5ra23766a ◽

2016 ◽

Vol 6 (9) ◽

pp. 7348-7355 ◽

Cited By ~ 7

Author(s):

Anmin Liu ◽

Xuefeng Ren ◽

Jie Zhang ◽

Deyu Li ◽

Maozhong An

Keyword(s):

Electrochemical Behavior ◽

Environmentally Friendly ◽

Silver Complex ◽

Complexing Agent ◽

Silver Deposition ◽

Plating Bath ◽

Electrochemical Behaviors ◽

Silver Electrodeposition

Silver deposition and electrochemical behaviors of silver complex in the environmentally friendly silver plating bath were studied.

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

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.395-396.174 ◽

2013 ◽

Vol 395-396 ◽

pp. 174-178 ◽

Cited By ~ 1

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.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1049-1050.31 ◽

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.

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Electro-plastic metal cutting

Ferrous Metallurgy Bulletin of Scientific Technical and Economic Information ◽

10.32339/0135-5910-2019-6-735-740 ◽

2019 ◽

Vol 75 (6) ◽

pp. 735-740

Author(s):

O. A. Troitskii ◽

V. I. Stashenko

Keyword(s):

Cast Iron ◽

Friction Force ◽

Current Density ◽

Metal Cutting ◽

Pulse Current ◽

High Strength ◽

Heating Zone ◽

Current Density Vector ◽

Plastic Metal ◽

Density Vector

In the process of cutting of steels, high strength and heat-resistant alloys a strong warming-up of the cutting instrument takes place, necessitating its cooling by special emulsions and resulting in quick wear and increase of products cost. It was determined by experiment, that during a metal with current cutting, an electro-plastic effect arises. During the lector-plastic cutting, the plastic deformation of a metal under pulse current effect becomes easier, making the friction force between the metal chips and the cutting instrument front edge lower. The electro-plastic metal cutting method accounting the current polarity, current density vector directions, as well as pulse current parameters, can considerably improve the cut surface microstructure and increase the instrument service life. At that, the thermal regime of the cutting can be lowered due to cutting force lowering and heating zone shifting inside the piece or the instrument due to Thomson effect. It was shown, that during the electro-plastic metal cutting the friction force can decrease by 25–30% at the favorable current density vector orientation, as it takes place during electro-static metal drawing and rolling. The current plasticizing action results in decreasing friction force and the chips twisting radius, which can be confluent even for cast iron. At the example of metal drilling with the pulse current, the important current effects on the cutting mechanical parameters revealed. The conditions of metal electro-plastic cutting stated. Results of the experiment study of metal electro-plastic cutting quoted for the processes of steel and cast iron drilling.

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Porosification Analysis on the Effect of Resistivity Dependence on N-Type Pulsed Porous Silicon

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.301.12 ◽

2020 ◽

Vol 301 ◽

pp. 12-17

Author(s):

Nurul Hanida Abd Wahab ◽

Alhan Farhanah Abd Rahim ◽

Ainorkhilah Mahmood ◽

Noorezal Atfyinna Mohammed Napiah ◽

Rosfariza Radzali ◽

...

Keyword(s):

Porous Silicon ◽

Surface Morphology ◽

Direct Current ◽

Current Density ◽

Cycle Time ◽

Pulse Generator ◽

Pulse Current ◽

Etching Process ◽

Homogeneous Structure ◽

Photoelectrochemical Etching

A set of n-type porous silicon (PS) layers were fabricated by photoelectrochemical etching using direct current (DC) and pulse current (PC) techniques. The study aims to compare the effect of different resistivity (5 Ω and 10 Ω) on the formation of the PS structure. The samples were etched in a solution of HF:C2H6O with a composition ratio of 1:4. The etching process were done for 30 minutes with the current density of J = 10 mA/cm2. In the time of PC etching process, the current was supplied through a pulse generator with 14 ms cycle time (T) which the on time (Ton) set to 10 ms and pause time (Toff) set to 4 ms respectively. The samples were then being characterized in terms of surface morphology by using FESEM, AFM and XRD. Through the FESEM results, it can be seen that sample with 10 Ω resistivity which using PC form a more homogeneous structure of pores as compared to other samples.

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Calcium Phosphate Based Bioactive Ceramic Layers on Implant Materials Preparation, Properties, and Biological Performance

Coatings ◽

10.3390/coatings10090823 ◽

2020 ◽

Vol 10 (9) ◽

pp. 823

Author(s):

Monika Furko ◽

Csaba Balázsi

Keyword(s):

Calcium Phosphate ◽

Current Density ◽

Pulse Current ◽

Ph Value ◽

Biological Response ◽

Biological Properties ◽

Implant Materials ◽

Foreign Materials ◽

Biological Performance ◽

Implant Coatings

Calcium phosphate based bioactive ceramics (CPCs) can be successfully applied as implant coatings since they are chemically similar to the inorganic constituent of hard tissues (bones, teeth). Nowadays, in orthopedic surgeries, it is still common to use metallic implants. However, the biological response of the human body to these foreign materials can be adverse, causing the failure of implant materials. This disadvantage can be avoided by bioactive coatings on the surface of implants. CPCs can be prepared by different routes that provide coatings of different quality and properties. In our paper, we compared the morphological, chemical, and biological properties of CPC coatings prepared by the pulse current electrochemical method. The size and thickness of the pulse current deposited platelets largely depended on the applied parameters such as the length of ton and the current density. The decrease in the ton/toff ratio resulted in thinner, more oriented platelets, while the increase in current density caused a significant decrease in grain size. The higher pH value and the heat treatment favored the phase transformation of CPCs from monetite to hydroxyapatite. The contact angle measurements showed increased hydrophilicity of the CPC sample as well as better biocompatibility compared to the uncoated implant material.

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