scholarly journals Comparative analysis of the polarization and morphological characteristics of electrochemically produced powder forms of the intermediate metals

2014 ◽  
Vol 33 (2) ◽  
pp. 169 ◽  
Author(s):  
Nebojsa D. Nikolic ◽  
Predrag M. Zivkovic ◽  
Bojan Jokic ◽  
Miomir G. Pavlovic ◽  
Jasmina S. Stevanovic
Keyword(s):  
Surface Morphology ◽  
Current Density ◽  
Morphological Characteristics ◽  
Copper Surface ◽  
Diffusion Current ◽  
Copper Electrodeposition ◽  
Continuous Change ◽  
Polarization Characteristics ◽  
High Overpotentials ◽  
Limiting Diffusion Current

The polarization and morphological characteristics of powder forms of the group of the intermediate metals were examined by the analysis of silver and copper electrodeposition processes at high overpotentials. The pine-like dendrites constructed from the corncob-like forms, very similar to each others, were obtained by electrodeposition of these metals at the overpotential belonging to the plateaus of the limiting diffusion current density. The completely different situation was observed by electrodeposition of silver and copper at the overpotential outside the plateaus of the limiting diffusion current density in the zone of the fast increase of the current density with the overpotential. The silver dendrites, very similar to silver and copper dendrites obtained inside the plateaus of the limiting diffusion current density, were obtained at the overpotential outside the plateau. Due to the lower overpotential for hydrogen evolution for copper, hydrogen produced during copper electrodeposition process strongly affected the surface morphology of copper. The same shape of the polarization curves with the completely different surface morphology of Cu and Ag electrodeposited at overpotentials after the inflection point clearly indicates on the importance of morphological analysis in the investigation of polarization characteristics of the electrodeposition systems. Role of hydrogen as crucial parameter in the continuous change of copper surface morphology from dendrites to the honeycomb-like structures was investigated in detail. On the basis of this analysis, the transitional character of the intermediate metals between the normal and inert metals was considered. The typical powder forms characterizing electrodeposition of the intermediate metals were also defined and systematized.

scholarly journals The ionic equilibrium in the CuSO4-H2SO4-H2O system and the formation of the honeycomb-like structure during copper electrodeposition

2008 ◽  
Vol 73 (7) ◽  
pp. 753-760 ◽  
Author(s):  
Nebojsa Nikolic ◽  
Ljubica Pavlovic ◽  
Goran Brankovic ◽  
Miomir Pavlovic ◽  
Konstantin Popov
Keyword(s):  
Hydrogen Evolution ◽  
Current Density ◽  
Diffusion Current ◽  
Copper Electrodeposition ◽  
Hydrodynamic Conditions ◽  
Ionic Equilibrium ◽  
Electrode Layer ◽  
Limiting Diffusion Current

The ionic equilibrium of the species in the CuSO4-H2SO4-H2O system was employed to systematize the conditions of copper electrodeposition leading to the formation of the honeycomb-like structure. The reason why CuSO4 concentrations higher than 0.15 M are unsuitable for the formation of honeycomb-like structures is shown. The range of H2SO4 concentrations enabling the formation of this type of structure was also determined. The conditions leading to the formation of the honeycomb-like structures are: electrodeposition from solutions with lower concentrations of Cu(II) ions (0.15 M CuSO4 and less) in a concentration range from 0.25 to 1.0 M H2SO4, at a temperature of 18.0?1.0 ?C and at overpotentials outside the plateau of the limiting diffusion current density at which hydrogen evolution is vigorous enough to change the hydrodynamic conditions in the near-electrode layer. .

scholarly journals Copper deposits obtained by pulsating overpotential regime with a long pause and pulse duration from sulfated solutions

2020 ◽  
Vol 85 (6) ◽  
pp. 795-807
Author(s):  
Fatemeh Shafiei ◽  
Kourosh Jafarzadeh ◽  
Ali Madram
Keyword(s):  
Current Density ◽  
Sem Analysis ◽  
Diffusion Current ◽  
Electron Microscopic ◽  
Copper Deposits ◽  
H2so4 Concentration ◽  
Scanning Electron Microscopic ◽  
Polarization Characteristics ◽  
Pulsating Overpotential ◽  
Limiting Diffusion Current

The morphologies of the copper deposits obtained by pulsating overpotential regime with prolonged pulse and pause durations from the solution of 0.15 M CuSO4 in 0.50 M H2SO4 at overpotentials lower, higher and belonging to the plateau of limiting diffusion current density were compared with those obtained by the same electrodeposition regime from solutions of 0.075 and 0.30 M CuSO4 in 0.50 M H2SO4 and 0.15 M CuSO4 in 0.25 and 1.00 M H2SO4 at overpotentials outside the plateau of limiting diffusion current density. These samples were characterized by scanning electron microscopic (SEM) analysis and the cathodic polarization characteristics from solutions compared. Increasing the Cu(II) concentration led to an increase in the limiting diffusion current density. Decreasing the H2SO4 concentration shifts both beginning and the end of the plateau of the limiting diffusion current density towards higher electrodeposition overpotentials. Also, electrodeposition in solutions of 0.15 M CuSO4 in 0.25 and 1.00 M H2SO4 led to the formation of morphological forms of copper deposits characteristic for electrodeposition of copper from higher CuSO4 or lower H2SO4 in solution at some higher overpotentials.

scholarly journals Estimation of the exchange current density and comparative analysis of morphology of electrochemically produced lead and zinc deposits

2017 ◽  
Vol 82 (5) ◽  
pp. 539-550
Author(s):  
Nebojsa Nikolic ◽  
Predrag Zivkovic ◽  
Goran Brankovic ◽  
Miomir Pavlovic
Keyword(s):  
Current Density ◽  
Exchange Current ◽  
Exchange Current Density ◽  
Diffusion Current ◽  
Electron Microscopic ◽  
Zinc Electrodeposition ◽  
Lead And Zinc ◽  
Current Densities ◽  
Limiting Diffusion Current ◽  
Zinc Deposits

The processes of lead and zinc electrodeposition from the very dilute electrolytes were compared by the analysis of polarization characteristics and by the scanning electron microscopic (SEM) analysis of the morphology of the deposits obtained in the galvanostatic regime of electrolysis. The exchange current densities for lead and zinc were estimated by comparison of experimentally obtained polarization curves with the simulated ones obtained for the different the exchange current density to the limiting diffusion current density ratios. Using this way for the estimation of the exchange current density, it is shown that the exchange current density for Pb was more than 1300 times higher than the one for Zn. In this way, it is confirmed that the Pb electrodeposition processes are considerably faster than the Zn electrodeposition processes. The difference in the rate of electrochemical processes was confirmed by a comparison of morphologies of lead and zinc deposits obtained at current densities which corresponded to 0.25 and 0.50 values of the limiting diffusion current densities.

scholarly journals Effect of temperature on the electrodeposition of disperse copper deposits

2007 ◽  
Vol 72 (12) ◽  
pp. 1369-1381 ◽  
Author(s):  
Nebojsa Nikolic ◽  
Ljubica Pavlovic ◽  
Miomir Pavlovic ◽  
Konstantin Popov
Keyword(s):  
Current Density ◽  
Sem Analysis ◽  
Diffusion Current ◽  
Effect Of Temperature ◽  
Electron Microscopic ◽  
Copper Deposits ◽  
Disperse Copper ◽  
Average Current ◽  
Limiting Diffusion Current

The effect of temperature on the electrodeposition of copper at overpotentials belonging to the plateau of the limiting diffusion current density and higher was examined by the determination of the average current efficiency of hydrogen evolution and by scanning electron microscopic (SEM) analysis of the morphology of the formed copper deposits. Increasing the temperature of the solution led to a shift of both the beginning and the end of the plateau of the limiting diffusion current density towards lower electrodeposition overpotentials. Also, higher temperatures led to the formation of morphological forms of copper deposits characteristic for electrodeposition of copper at some higher overpotentials. The unexpected trend in the development of copper structures electrodeposited at an overpotential of 800 mV is discussed in terms of the effect of temperature on the viscosity and surface tension of the electroplating solution.

scholarly journals Relationship between cathodic protection current and limit diffusion current as an additional criteria of cathodic protection

2019 ◽  
pp. 23-31
Author(s):  
L. I. Nyrkova ◽  
S. O. Osadchuk ◽  
А. V. Klymenko ◽  
А. О. Rybakov ◽  
S. L. Melnychuk
Keyword(s):  
Oxygen Concentration ◽  
Current Density ◽  
Cathodic Protection ◽  
Diffusion Current ◽  
Effect Of Temperature ◽  
Electrochemical Characteristics ◽  
Time Data ◽  
Limit Diffusion Current ◽  
Effect Of Oxygen ◽  
Limiting Diffusion Current

The influence of the temperature and oxygen concentration in NS4 solution on the electrochemical characteristics of X70 steel for pipelines and the relationship of cathodic protection current density to limiting diffusion current density, in the normalized DSTU 4219 range of protective polarization potentials from -0.75 V to    -1.05 V (сh.s.е.) were investigated. It has been established that with increasing of the temperature from 20 to 80 °C, the corrosion activity of X70 steel increases, which is confirmed by more negative values of corrosion potential and an increasing of the corrosion rate, and indicates on the prevailing effect of temperature on the corrosion process compared to the effect of oxygen concentration. In the temperature range considered, the limiting diffusion current has a maximum value at 40 °C and decreases with increasing of temperature, correlating with a decreasing of the oxygen concentration. Under conditions of free oxygen access to the NS4 solution in the normalized DSTU 4219 range of protective polarization potentials, the ratio of cathodic protection to limiting diffusion  current varies from 0.4 to 1.3 at temperatures (20-40) oС, at temperatures (60-80) oC the ratio  is less than 1. Under conditions of limited oxygen access, the ratio  increases from 1.1 to 4.7. Using calculated and experimental results, it was shown that, at various values of relationship , conditions for excessive hydrogen evolution can be created, which represents a threat to the safe operation of the pipeline over time.  Data on the ratio values  should be taken into account when analyzing the protection state of pipelines.

Study on Electrodeposition of Ni-Graphite Composite Coatings in Sulfamate Bath

2010 ◽  
Vol 150-151 ◽  
pp. 1546-1550 ◽  
Author(s):  
Xiang Zhu He ◽  
Xiao Wei Zhang ◽  
Xin Li Zhou ◽  
Zhi Hong Fu
Keyword(s):  
Surface Morphology ◽  
Process Parameters ◽  
Current Density ◽  
Graphite Particle ◽  
Particle Concentration ◽  
Composite Coatings ◽  
Nickel Matrix ◽  
Graphite Composite ◽  
Surface Morphologies ◽  
Sulfamate Bath

This paper presented the composite coatings of nickel with graphite particle on the aluminum substrate using a nickel sulfamate bath. Effects of graphite particle concentration on the surface morphologies of the composite coatings were investigated. The inclusion of graphite particle into metal deposits was dependent on many process parameters, including particle concentration, current density, pH and temperature. Results of SEM and XRD demonstrated that graphite particle had successfully deposited on that nickel matrix; besides, the surface morphology of coatings obtained from sulfamate bath containing 2g/L graphite particle dispersed more uniformly than the ones with higher concentration.

Polarization Characteristics to Wear Ratio of Anti-Fouling Paint

2015 ◽  
Vol 1110 ◽  
pp. 179-184
Author(s):  
Kyung Man Moon ◽  
Dong Hyun Park ◽  
Yun Hae Kim ◽  
Tae Sil Baek
Keyword(s):  
Current Density ◽  
Corrosion Potential ◽  
Wear Test ◽  
Life Time ◽  
Point Of View ◽  
Limiting Current ◽  
Limiting Current Density ◽  
Wear Ratio ◽  
Polarization Characteristics ◽  
Lower Variation

Recently, anti-fouling paints which does not include the poison components such as tin (Sn) free, copper (Cu) free have been increasingly developed in order to decrease the contamination of marine environment. Moreover, the wear ratios of these anti-fouling paints are very important problem to prolong their life time in economical and environmental point of view. In this study, four types of anti-fouling paints as self-polishing type were investigated on the relationship between their polarization characteristics and wear ratios. Relationship between wear ratio and variation ratio of polarization resistance measured in corrosion potential was not well matched with each other. However, there was a good agreement between the wear ratio and variation ratio of diffusion limiting current density, for example, the higher or the lower variation ratio of diffusion limiting current density, wear ratio also increased or decreased respectively. Consequently, it is suggested that we can qualitatively expect the life time and wear degree of anti-fouling paint by only measuring the polarization characteristics before the wear test is practically performed in the field.Keywords: Anti-fouling paint, Self-polishing type, Polarization characteristics, Wear ratio, Diffusion limiting current density, Corrosion Potential

scholarly journals Numerical Model for Simulation of the Cathodic Protection System with Dynamic Nonlinear Polarization Characteristics

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Numerical Model ◽  
Current Density ◽  
Cathodic Protection ◽  
Electric Potential ◽  
Protection System ◽  
Nonlinear Polarization ◽  
Electrode Surfaces ◽  
Polarization Characteristics ◽  
Cathodic Protection System

Cathodic protection is defined as a method for slowing down or complete elimination of corrosion processes on underground or underwater, insulated or uninsulated metal structures. Protection by cathodic protection system is achieved by polarizing protected object to more negative value, with respect to its equilibrium potential. Design of the cathodic protection system implies determination of the electric potential and current density on the electrode surfaces after installation of the cathodic protection system. Most efficient way for determination of the electric potential and current density in the cathodic protection system is by applying numerical techniques. When modeling cathodic protection systems by numerical techniques, electrochemical reactions that occur on electrode surfaces are taken into account by polarization characteristics. Because of nature of the electrochemical reactions, polarization characteristics are nonlinear and under certain conditions can be time – varying (dynamic nonlinear polarization characteristics). This paper deals with numerical modeling of the cathodic protection system with dynamic nonlinear polarization characteristics. Numerical model presented in this paper is divided in the two parts. First part, which is based on the direct boundary element method, is used for the calculation of the distribution of electric potential and current density on the electrode surfaces in the spatial domain. Second part of the model is based on the finite difference time domain method and is used for the calculation of the electric potential and current density change over time. The use of presented numerical model is demonstrated on two simple geometrically examples.

THE EFFECT OF PREPARED PARAMETERS ON THE MICROSTRUCTURE OF ELECTRODEPOSITED NANOCRYSTALLINE NICKEL COATING

2004 ◽  
Vol 11 (04n05) ◽  
pp. 433-442 ◽  
Author(s):  
C. Y. DAI ◽  
Y. PAN ◽  
S. JIANG ◽  
Y. C. ZHOU
Keyword(s):  
Grain Size ◽  
Surface Morphology ◽  
Current Density ◽  
Crystal Orientation ◽  
Nickel Coating ◽  
Pulse Frequency ◽  
Lattice Parameter ◽  
Nanocrystalline Nickel ◽  
Peak Current Density ◽  
Peak Current

The nanocrystalline nickel coating was synthesized by pulse-jet electrodeposition from modified Watts bath. Pulse and jet plating was employed to increase the deposition current density, decrease diffusion layer, increase the nucleation rate and in this case the prepared method would result in fine-grained deposits. Transmission and scanning electron microscopy and X-ray diffraction (XRD) were used to study the microstructure, the surface morphology, the crystal preferred orientation and the variety of the lattice parameter respectively. The influence of pulse parameters, namely peak current density, the duty cycle and pulse frequency on the grain size, surface morphology, crystal orientation and microstructure was studied. The results showed that with increasing peak current density, the deposit grain size was found to decrease markedly in other parameters at constant. However, in our experiment it was found that the grain size increased slightly with increasing pulse frequency. For higher peak current density, the surface morphology was smoother. The crystal orientation progressively changed from an almost random distribution to a strong (111) texture. This means that the peak current density was the dominated parameter to effect the microstructure of electrodeposited nanocrystalline nickel coating. In addition, the lattice parameter for the deposited nickel is calculated from XRD and it is found that the calculated value is less than the lattice parameter for the perfect nickel single crystal. This phenomenon is explained by the crystal lattice mismatch.

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