Vladimir Volgin - Academia.edu (original) (raw)

Papers by Vladimir Volgin

Diffuse-charge effects are of importance for the transport processes in the electrochemical syste... more Diffuse-charge effects are of importance for the transport processes in the electrochemical systems, especially when the ultra-short pulses are used. At present, two main approaches to the consideration of the effects of electrical double layer are commonly used: (a) an approach, which is based on the generalized Frumkin-Butler- Volmer theory; it takes into account the effect of diffuse double layer and the variation in the concentrations of ions on its outer boundary; (b) an approach, which takes into account the ohmic losses in the bulk electrolyte solution and a potential drop in the Helmholtz layer. In the first approach, the Poisson’s equation is used to determine the electric field in the diffuse and diffusion layers. This hampers significantly the numerical solution of the problem; the highly efficient methods, which are used to advantage for the electrically neutral systems, cannot be used in this case. In the second approach, the variations in the concentrations in the diff...

2019 International Russian Automation Conference (RusAutoCon), 2019

The paper deals with modeling of dimensional electrochemical machining using nanosecond voltage p... more The paper deals with modeling of dimensional electrochemical machining using nanosecond voltage pulses with different duration of the front and rear edges of the voltage pulse. A differential equation that takes into account the ohmic losses in the electrolyte solution, the charging of the double electric layer and the resistance of the electrochemical reaction was used as a mathematical model. The influence of the nanopulse current parameters on the anodic dissolution rate and the initial inaccuracy reducing was revealed. The investigation of the choice of the voltage pulse duration to ensure effective reducing of the initial inaccuracy was carried out.

Procedia CIRP, 2016

The process of the micro electrochemical machining with the ultra small interelectrode gap withou... more The process of the micro electrochemical machining with the ultra small interelectrode gap without the electrode-tool displacement for the flushing with the workpiece scanning by the electrode-tool and with F et /F wp = 0.5-25 % is considered in the publication. The modeling of the MECM process at the various electrode-tool paths on X-and Y-axes with periodic updating of the UIEG on Z-axis during the anode dissolution of the workpiece is executed.

Procedia CIRP, 2015

Ke 1. I nan fiel bio nan inte bet fun sup pro tou cha exp den am nan fab tem M ele orresponding a... more Ke 1. I nan fiel bio nan inte bet fun sup pro tou cha exp den am nan fab tem M ele orresponding aut stract ectrochemical d riodical nanostr position, in par face evolution tential and depo e numerical exp initial distribut 2015 The Autho lection and peer rson of the Conf eywords: Elec

The work is devoted to the theoretical study of natural-convective instability of electrolyte lay... more The work is devoted to the theoretical study of natural-convective instability of electrolyte layer between horizontal plane electrodes, which execute harmonic high frequency vibrations along a fixed direction. The high-frequency vibrations were taken into consideration by the method of averaging. The method enables one to analyze stability using the Navier-Stokes equations for the velocity, which is averaged over the vibration period, and the equation for the solenoidal part of buoyancy force projection onto the vibration direction. Otherwise, the mathematical description of the problem, which allowed us to take into consideration the kinetics of electrode reaction and the perturbations of electrode potentials, corresponded to [1]. In the mathematic model, the effect of vibration is characterized by three parameters: the dimensionless amplitude, angular velocity and direction of vibration. Stability of undisturbed state of the system for averaged velocity, concentration, and potent...

The model of electrochemical growth of ordered arrays of high aspect ratio nanowires in the nonco... more The model of electrochemical growth of ordered arrays of high aspect ratio nanowires in the nonconducting template is developed.1 The initial non-steady-state period of the process is ignored, because its duration is by two orders of magnitude shorter than the pore filling time. It is taken into account that the metal deposition depends both on the conditions of metal cations diffusion and on the overpotential by the Tafel equation. The mass transfer in the outer diffusion layer above the template surface and a possible difference between the diffusion coefficients of electroactive ions in the inner diffusion layer (in the pore) and in the outer diffusion layer are considered. An approximation of uniform outer diffusion layer is used. Within the model, the exact solution is obtained for the potentiostatic mode of metal deposition in the pores. With regard for the template porosity, several characteristics of the process are obtained: the time dependences of current and concentration...

Pulsatile and oscillative flows are frequently encountered in various engineering systems with he... more Pulsatile and oscillative flows are frequently encountered in various engineering systems with heat and mass transfer. In the electrochemistry, pulsatile flow is used for determining the amplitude-frequency dependences of current or electrode potential on the modulation frequency of hydrodynamic velocity or gradient of pressure (the method of electrohydrodynamic impedance, the electrochemical transducers), and also for enhancing mass transfer for detecting ultra-small concentrations of environmental and biological analytes (the hydrodynamic modulation voltammetry). In almost all of the works devoted to the theoretical analysis of mass transfer in the electrolyte solutions in the cases of the pulsatile and oscillative flows, the migration transfer of ions is ignored. This simplifies significantly the problem solution and enables one to apply the methods, which were developed for the heat systems. However, this restricts the range of applicability of calculated results by two limiting...

Template-assisted electrodeposition is an important technique for synthesizing metallic nanomater... more Template-assisted electrodeposition is an important technique for synthesizing metallic nanomaterials with controlled shape and size. In spite of increasing interest in this method, the majority of the works devoted to the template-assisted electrodeposition are the experimental studies. The development of the theory and time-saving methods of simulating the transfer processes in the electrochemical systems with templates is a condition for effective application of template-assisted electrodeposition. Earlier, simple models of transfer processes through a template with regularly arranged pores were developed. The multi-level approach was realized. The space near the cathode surface was divided into several zones with different characteristics of transfer processes. In these works, the migration transfer of ions was ignored. The cases of the electrodeposition under different types of kinetic limitations were considered. Here, we develop the method of simulation of template-assisted e...

The metal electrodeposition through a colloidal crystal mask is simulated by using the multi-leve... more The metal electrodeposition through a colloidal crystal mask is simulated by using the multi-level approach. The space near the cathode surface is divided into several zones with different characteristics of transport processes. In each zone, 1D or 3D approximation may be used. In the zones of 1D type, the distributions of electroactive ion concentration and potential are calculated by the analytical equations; in the zones of 3D type, the numerical finite element method is used 1. The transport processes in the neighboring zones are conjugated by using the condition of equal currents through the boundary between these zones. In this work, we develop the method of modeling the metal electrodeposition in the solution with an excess of supporting electrolyte: the migration transfer of all ions is taken into account and the electrode reaction governed by the equation of Butler-Volmer is considered. The developed mathematical model involves the Laplace equation for the concentration of ...

Russian Journal of Electrochemistry, 2005

Introduction. When a current is passed through a stagnant solution between two horizontal electro... more Introduction. When a current is passed through a stagnant solution between two horizontal electrodes, two states of the system can be observed: (1) The solution remains stagnant in spite of the variation in its density ρ near the electrodes. The buoyancy forces are balanced by the viscosity forces. (2) The buoyancy force initiates convective instability, the initially stagnant solution starts to flow: a solution with a higher density, which forms near the upper electrode, flows downward, and a solution with a lower density, which forms near the lower electrode, flows upward. For the limiting-current mode, to the approximation of solution electroneutrality, the problem of Rayleigh-Benard instability for a binary electrolyte is equivalent to the problem of heat convection that has been much studied [1, 2, 3, 4, 5]. In this case, only a monotonic convective instability can arise [6]. In a solution with a more complex composition, an oscillatory instability can arise along with the monotonic one. Several works were devoted to the study of monotonic and oscillatory instabilities in electrochemical systems with three types of ions [7, 8]. In these works, approximate solutions of the problem for the cathodic deposition (anodic dissolution) of metal were obtained. Systems with redox reactions were not considered in the literature. Moreover, the Rayleigh numbers, which were used in these studies, differ from the commonly accepted values. The problem of Rayleigh-Benard for heat convection in the magnetic field was studied by Chandrasekhar [1]. In this work, we will theoretically analyze the conditions of the onset of monotonic and oscillatory free-convective instabilities in the solution with three types of ions with concentrations c 1 , c 2 , and c 3 , diffusion coefficients D 1 , D 2 and D 3 , and charges z 1 , z 2 and z 3 , which is placed in the space between two plane horizontal electrodes, taking into account the migration transfer of a supporting electrolyte. The effect of applied magnetic field on the onset of free convective instability is discussed.

Russian Journal of Electrochemistry, 2004

Basic problems of metal electrochemical shaping theory are considered. Exact and approximate (qua... more Basic problems of metal electrochemical shaping theory are considered. Exact and approximate (quasi-steady-state, locally one-dimensional) methods for solving direct and inverse problems are analyzed. Experimental methods for improving the electrochemical shaping accuracy are considered.

Russian Journal of Electrochemistry, 2006

ABSTRACT

Russian Journal of Electrochemistry, 2008

Russian Journal of Electrochemistry, 2010

ABSTRACT The mass transfer in the rotating electrochemical cell with vertical cylindrical electro... more ABSTRACT The mass transfer in the rotating electrochemical cell with vertical cylindrical electrodes containing a binary electrolyte is theoretically studied. The Navier-Stokes equations in the rotating system of coordinates, the equations of ionic transfer of electrolyte components, which is caused by diffusion, convection, and migration, and the condition of electroneutrality are used as the mathematic model of the process. The effects of centrifugal force and Coriolis force are studied by using the numerical simulation; the effect of geometry of electrochemical cell on the limiting mass transfer rate is determined.

Physics of Fluids, 2013

The stability of a mechanical quasi-equilibrium state of a binary electrolyte layer between plana... more The stability of a mechanical quasi-equilibrium state of a binary electrolyte layer between planar horizontal electrodes subjected to high-frequency vibration is studied theoretically. It is assumed that reversible anodic metal dissolution and cathodic reactions proceed at the layer boundaries (metal electrode surfaces). A linear analysis of the convective stability is based on a system of equations for averaged fields of hydrodynamic velocity, concentration, and electric potential. An analytical solution to the stability problem with respect to the long-wave perturbations is obtained for positive and negative Rayleigh numbers. It is shown that the Rayleigh number corresponding to the boundary of long-wave instability depends on the direction of vibration, transport properties of the solution, and vibration frequency and amplitude. Approximate analytical solutions of the problem for monotonic instability under horizontal and vertical vibrations are obtained. The stability boundaries...

Journal of Membrane Science, 2005

ABSTRACT

Journal of Materials Processing Technology, 2004

ABSTRACT

Journal of Electroanalytical Chemistry, 2007

ABSTRACT

Diffuse-charge effects are of importance for the transport processes in the electrochemical syste... more Diffuse-charge effects are of importance for the transport processes in the electrochemical systems, especially when the ultra-short pulses are used. At present, two main approaches to the consideration of the effects of electrical double layer are commonly used: (a) an approach, which is based on the generalized Frumkin-Butler- Volmer theory; it takes into account the effect of diffuse double layer and the variation in the concentrations of ions on its outer boundary; (b) an approach, which takes into account the ohmic losses in the bulk electrolyte solution and a potential drop in the Helmholtz layer. In the first approach, the Poisson’s equation is used to determine the electric field in the diffuse and diffusion layers. This hampers significantly the numerical solution of the problem; the highly efficient methods, which are used to advantage for the electrically neutral systems, cannot be used in this case. In the second approach, the variations in the concentrations in the diff...

2019 International Russian Automation Conference (RusAutoCon), 2019

The paper deals with modeling of dimensional electrochemical machining using nanosecond voltage p... more The paper deals with modeling of dimensional electrochemical machining using nanosecond voltage pulses with different duration of the front and rear edges of the voltage pulse. A differential equation that takes into account the ohmic losses in the electrolyte solution, the charging of the double electric layer and the resistance of the electrochemical reaction was used as a mathematical model. The influence of the nanopulse current parameters on the anodic dissolution rate and the initial inaccuracy reducing was revealed. The investigation of the choice of the voltage pulse duration to ensure effective reducing of the initial inaccuracy was carried out.

Procedia CIRP, 2016

The process of the micro electrochemical machining with the ultra small interelectrode gap withou... more The process of the micro electrochemical machining with the ultra small interelectrode gap without the electrode-tool displacement for the flushing with the workpiece scanning by the electrode-tool and with F et /F wp = 0.5-25 % is considered in the publication. The modeling of the MECM process at the various electrode-tool paths on X-and Y-axes with periodic updating of the UIEG on Z-axis during the anode dissolution of the workpiece is executed.

Procedia CIRP, 2015

Ke 1. I nan fiel bio nan inte bet fun sup pro tou cha exp den am nan fab tem M ele orresponding a... more Ke 1. I nan fiel bio nan inte bet fun sup pro tou cha exp den am nan fab tem M ele orresponding aut stract ectrochemical d riodical nanostr position, in par face evolution tential and depo e numerical exp initial distribut 2015 The Autho lection and peer rson of the Conf eywords: Elec

The work is devoted to the theoretical study of natural-convective instability of electrolyte lay... more The work is devoted to the theoretical study of natural-convective instability of electrolyte layer between horizontal plane electrodes, which execute harmonic high frequency vibrations along a fixed direction. The high-frequency vibrations were taken into consideration by the method of averaging. The method enables one to analyze stability using the Navier-Stokes equations for the velocity, which is averaged over the vibration period, and the equation for the solenoidal part of buoyancy force projection onto the vibration direction. Otherwise, the mathematical description of the problem, which allowed us to take into consideration the kinetics of electrode reaction and the perturbations of electrode potentials, corresponded to [1]. In the mathematic model, the effect of vibration is characterized by three parameters: the dimensionless amplitude, angular velocity and direction of vibration. Stability of undisturbed state of the system for averaged velocity, concentration, and potent...

The model of electrochemical growth of ordered arrays of high aspect ratio nanowires in the nonco... more The model of electrochemical growth of ordered arrays of high aspect ratio nanowires in the nonconducting template is developed.1 The initial non-steady-state period of the process is ignored, because its duration is by two orders of magnitude shorter than the pore filling time. It is taken into account that the metal deposition depends both on the conditions of metal cations diffusion and on the overpotential by the Tafel equation. The mass transfer in the outer diffusion layer above the template surface and a possible difference between the diffusion coefficients of electroactive ions in the inner diffusion layer (in the pore) and in the outer diffusion layer are considered. An approximation of uniform outer diffusion layer is used. Within the model, the exact solution is obtained for the potentiostatic mode of metal deposition in the pores. With regard for the template porosity, several characteristics of the process are obtained: the time dependences of current and concentration...

Pulsatile and oscillative flows are frequently encountered in various engineering systems with he... more Pulsatile and oscillative flows are frequently encountered in various engineering systems with heat and mass transfer. In the electrochemistry, pulsatile flow is used for determining the amplitude-frequency dependences of current or electrode potential on the modulation frequency of hydrodynamic velocity or gradient of pressure (the method of electrohydrodynamic impedance, the electrochemical transducers), and also for enhancing mass transfer for detecting ultra-small concentrations of environmental and biological analytes (the hydrodynamic modulation voltammetry). In almost all of the works devoted to the theoretical analysis of mass transfer in the electrolyte solutions in the cases of the pulsatile and oscillative flows, the migration transfer of ions is ignored. This simplifies significantly the problem solution and enables one to apply the methods, which were developed for the heat systems. However, this restricts the range of applicability of calculated results by two limiting...

Template-assisted electrodeposition is an important technique for synthesizing metallic nanomater... more Template-assisted electrodeposition is an important technique for synthesizing metallic nanomaterials with controlled shape and size. In spite of increasing interest in this method, the majority of the works devoted to the template-assisted electrodeposition are the experimental studies. The development of the theory and time-saving methods of simulating the transfer processes in the electrochemical systems with templates is a condition for effective application of template-assisted electrodeposition. Earlier, simple models of transfer processes through a template with regularly arranged pores were developed. The multi-level approach was realized. The space near the cathode surface was divided into several zones with different characteristics of transfer processes. In these works, the migration transfer of ions was ignored. The cases of the electrodeposition under different types of kinetic limitations were considered. Here, we develop the method of simulation of template-assisted e...

The metal electrodeposition through a colloidal crystal mask is simulated by using the multi-leve... more The metal electrodeposition through a colloidal crystal mask is simulated by using the multi-level approach. The space near the cathode surface is divided into several zones with different characteristics of transport processes. In each zone, 1D or 3D approximation may be used. In the zones of 1D type, the distributions of electroactive ion concentration and potential are calculated by the analytical equations; in the zones of 3D type, the numerical finite element method is used 1. The transport processes in the neighboring zones are conjugated by using the condition of equal currents through the boundary between these zones. In this work, we develop the method of modeling the metal electrodeposition in the solution with an excess of supporting electrolyte: the migration transfer of all ions is taken into account and the electrode reaction governed by the equation of Butler-Volmer is considered. The developed mathematical model involves the Laplace equation for the concentration of ...

Russian Journal of Electrochemistry, 2005

Introduction. When a current is passed through a stagnant solution between two horizontal electro... more Introduction. When a current is passed through a stagnant solution between two horizontal electrodes, two states of the system can be observed: (1) The solution remains stagnant in spite of the variation in its density ρ near the electrodes. The buoyancy forces are balanced by the viscosity forces. (2) The buoyancy force initiates convective instability, the initially stagnant solution starts to flow: a solution with a higher density, which forms near the upper electrode, flows downward, and a solution with a lower density, which forms near the lower electrode, flows upward. For the limiting-current mode, to the approximation of solution electroneutrality, the problem of Rayleigh-Benard instability for a binary electrolyte is equivalent to the problem of heat convection that has been much studied [1, 2, 3, 4, 5]. In this case, only a monotonic convective instability can arise [6]. In a solution with a more complex composition, an oscillatory instability can arise along with the monotonic one. Several works were devoted to the study of monotonic and oscillatory instabilities in electrochemical systems with three types of ions [7, 8]. In these works, approximate solutions of the problem for the cathodic deposition (anodic dissolution) of metal were obtained. Systems with redox reactions were not considered in the literature. Moreover, the Rayleigh numbers, which were used in these studies, differ from the commonly accepted values. The problem of Rayleigh-Benard for heat convection in the magnetic field was studied by Chandrasekhar [1]. In this work, we will theoretically analyze the conditions of the onset of monotonic and oscillatory free-convective instabilities in the solution with three types of ions with concentrations c 1 , c 2 , and c 3 , diffusion coefficients D 1 , D 2 and D 3 , and charges z 1 , z 2 and z 3 , which is placed in the space between two plane horizontal electrodes, taking into account the migration transfer of a supporting electrolyte. The effect of applied magnetic field on the onset of free convective instability is discussed.

Russian Journal of Electrochemistry, 2004

Basic problems of metal electrochemical shaping theory are considered. Exact and approximate (qua... more Basic problems of metal electrochemical shaping theory are considered. Exact and approximate (quasi-steady-state, locally one-dimensional) methods for solving direct and inverse problems are analyzed. Experimental methods for improving the electrochemical shaping accuracy are considered.

Russian Journal of Electrochemistry, 2006

ABSTRACT

Russian Journal of Electrochemistry, 2008

Russian Journal of Electrochemistry, 2010

ABSTRACT The mass transfer in the rotating electrochemical cell with vertical cylindrical electro... more ABSTRACT The mass transfer in the rotating electrochemical cell with vertical cylindrical electrodes containing a binary electrolyte is theoretically studied. The Navier-Stokes equations in the rotating system of coordinates, the equations of ionic transfer of electrolyte components, which is caused by diffusion, convection, and migration, and the condition of electroneutrality are used as the mathematic model of the process. The effects of centrifugal force and Coriolis force are studied by using the numerical simulation; the effect of geometry of electrochemical cell on the limiting mass transfer rate is determined.

Physics of Fluids, 2013

The stability of a mechanical quasi-equilibrium state of a binary electrolyte layer between plana... more The stability of a mechanical quasi-equilibrium state of a binary electrolyte layer between planar horizontal electrodes subjected to high-frequency vibration is studied theoretically. It is assumed that reversible anodic metal dissolution and cathodic reactions proceed at the layer boundaries (metal electrode surfaces). A linear analysis of the convective stability is based on a system of equations for averaged fields of hydrodynamic velocity, concentration, and electric potential. An analytical solution to the stability problem with respect to the long-wave perturbations is obtained for positive and negative Rayleigh numbers. It is shown that the Rayleigh number corresponding to the boundary of long-wave instability depends on the direction of vibration, transport properties of the solution, and vibration frequency and amplitude. Approximate analytical solutions of the problem for monotonic instability under horizontal and vertical vibrations are obtained. The stability boundaries...

Journal of Membrane Science, 2005

ABSTRACT

Journal of Materials Processing Technology, 2004

ABSTRACT

Journal of Electroanalytical Chemistry, 2007

ABSTRACT