Zoran Stević | University of Belgrade (original) (raw)

Papers by Zoran Stević

U ovom radu su praćeni efekti toplote hidratacije različitih betona upotrebom termovizijske kamer... more U ovom radu su praćeni efekti toplote hidratacije različitih betona upotrebom termovizijske kamere i termodavača priključenih na osmokanalni sistem za monitoring temperature na bazi PC i LabVIEW paketa, razvijen za potrebe ovog istraživanja. Temperatura ambijenta (laboratorije) beležena je i memorisana pomoću posebnog digitalnog instrumenta. Praćenje temperature svežeg betona je trajalo 24h. Vršena su poređenja temperatura površine izmerenih termodavačima i termovizijskom kamerom. Na osnovu toga uspostavljene su korelaciju koje bi mogle dovesti do pojednostavljenja daljih ispitivanja, posebno masovnih

This paper describes a realization of a bipolar current source developed by the paper authors. Th... more This paper describes a realization of a bipolar current source developed by the paper authors. The source is intended for the application in galvanic and other industrial plants where pulse-reverse current supply is required (with the desired shape in time). A prototype of the device which provides the outcome current intensity up to ± 50 A, has been constructed. The hardware of the source consists of a PC Pentium IV, a commercial ADDA converter, an interface of authors' original construction as well as a current regulator. The application software is developed using a commercial packet LabView as the basis.

The history of gold deposition began in the early nineteenth century when many art objects were e... more The history of gold deposition began in the early nineteenth century when many art objects were electroplated with gold. It has been traced to the early work of Brugnatelli in 1805. Goldelectroplating formulations based on the double salt gold potassium cyanide was patented in 1840. Since then, gold has been plated from cyanide electrolytes, where (Au + ) is ligated with cyanide (CN - ).With regard to the two main disadvantages of cyanide electrolytes, toxicity and risks for technical personnel, there is a trend for using non-cyanide electrolytes. This article is an overview of the historyof gold coatings and investigations of gold complex based on mecaptotriazole.

Copper and brass, among others, are used in the processing industry, for heat exchangers, various... more Copper and brass, among others, are used in the processing industry, for heat exchangers, various fittings and connectors for water industry, pressure regulators, valves for bottles, parts for PPR fittings, contact blades, manometers, and others. Copper and brass are materials of widespread use for plumbing, hot water and electrical installations. However, regardless of their good corrosion properties, brass corrodes in water and the increased concentration of CO2 increases corrosion. The paper presents the application of lasers for the cleaning of copper and brass after exposure to corrosion. Nd: YAG laser with 1064nm wavelength, a pulse duration of 8ns and a pulse frequency of 20 Hz was used. The obtained results were taken with a light microscope, a spectrophotometer and a scanning electron microscope. The results were discussed and compared to the condition before the laser interaction.

Testiranje superkondenzatora due to the high capacitance, and therefore time constants, zahteva p... more Testiranje superkondenzatora due to the high capacitance, and therefore time constants, zahteva prilične modifikacije i prilagođavanje elektrohemijskih metoda i instrumentalnih tehnika. Ovaj rad obezbeđuje matematičku analizu koja definiše parametre eksperimentalnih metoda (galvanostatska metoda, potenciostatska metoda i ciklična voltametrija). Ključne reči: superkondezatori; elektrohemijske metode; matematički model; ekvivalentno električno kolo Testing supercapacitors due to the high capacitance, and therefore time constants, requires considerable modification and adaptation of classical electrochemical methods and instrumental techniques. This paper provides the mathematical analysis which defines the parameters of the experimental methods (galvanostatic method, potentiostatic method and cycling voltammetry).

International Journal of Electrochemical Science, 2021

In this paper, a computer-controlled voltage and current source, together with a response monitor... more In this paper, a computer-controlled voltage and current source, together with a response monitoring system for electrochemical investigations, is presented. The measuring system consisted of two major parts: the measuring hardware (HW) and the proprietary software. The hardware included the data acquisition USB card NI USB 6211 from National Instruments Company as well as all needed circuits (the analogue front end, the signal conditioning circuits, and power supplies). The software is based on the LabVIEW platform from National Instruments, and it is designed to control the signal generation and measurements, to cancel the noise in the signals, and to calibrate the device. The supported electrochemical methods are potential, potentiostatic and galvanostatic measurements, as well as the cyclic voltammetry and impedance measurments. The system was thoroughly tested, and it was determined that the system characteristics fulfil the requirements for most of the electrochemical and bioelectrochemical measurements, supercapacitor characteristics investigations, and much more. The overall system is modular; the HW and SW can easily be upgraded to support different methods and purposes and, therefore, the performance of the system.

International Journal of Materials Research, 2018

Pulse-reverse power modes are used in galvanotechniques in order to obtain coatings with better c... more Pulse-reverse power modes are used in galvanotechniques in order to obtain coatings with better characteristics in terms of gloss, adhesion, tracking sharp edges and uniform distribution of deposits on complex shape objects, compared with the coatings produced by constant current modes. Pulse-reverse modes also allow the use of a higher current density, and thus the production speed of electroplating cells increases. Systems for standard electroplating of copper, silver and gold are optimised by the suitable choice of duration and intensity of the pulses. It is shown that coatings with satisfactory quality can be deposited using higher current density, different modes of pulsed current in a very short period of time, without expensive and often dangerous additives in the electrolyte. Parameters of the model for certain electrochemical systems were determined by modelling and computer simulation, so the system behaviour under different circumstances becomes predictive.

2016 International Conference on Electronics and Information Technology (EIT), 2016

The paper gives a brief overview of computer controlled thermogravimetric analysis system. The sy... more The paper gives a brief overview of computer controlled thermogravimetric analysis system. The system consists of a personal computer, software, data acquisition card and interface for the provision of the necessary conditions for the analysis and adaptation of input and output signals. The entire control system, as well as the acquisition, recording and processing of measured data is solved by software. Application is based on programming package LabView.

Chemical Industry, 2009

The results of an attempt in using cyclic voltammetry for characterization of gold, silver, coppe... more The results of an attempt in using cyclic voltammetry for characterization of gold, silver, copper and 18-k gold alloys by their anodic behavior in 1 mol/dm3 H2SO4 are presented in this paper. Gold alloys containing 75 mass% Au are named as 18-k gold, but it is usually three component alloy containing 75 mass% Au, 12.5 mass% Ag and 12.5 mass% Cu as the main components. Investigated alloys were obtained by melting powders of pure metals mixed in corresponding ratio, casting, cooling in air, rolling and drawing in the wire shape. To achieve the required mechanical properties, the alloys had heat-treated three times. Each alloy exhibits characteristic current peaks on voltammogram that can be used to recognize the kind of present alloying metal in gold. Also, the content of the alloying metal can be roughly estimated from the peak value of current densities.

Chemical Industry, 2007

This paper describes an electrochemical research system based on the Lab VIEW computer software p... more This paper describes an electrochemical research system based on the Lab VIEW computer software package. An overview of well known electrochemical methods, such as potential measurements, chronopotentiometry, chronoamperometry, cyclic voltammetry and EIS is given. Electrochemical impedance spectroscopy has been adapted for systems containing large capacitances. For signal generation and recording of the response of the investigated electrochemical cell, a measurement and control system was developed, based on a PC P4 computer. The rest of the hardware consists of a commercially available AD-DA converter and an external interface for analog signal processing. The interface is a result of the authors own research. The software platform for the desired measurement methods is Lab VIEW package, which is regarded as a high standard in the area of modern virtual instruments. The developed system was adjusted, tested and compared with other commercially available systems. One such system is...

The corrosion behavior of copper was investigated by a constant sweep rate (0.01 V/s) and in diff... more The corrosion behavior of copper was investigated by a constant sweep rate (0.01 V/s) and in different corrosion media (1 M Na2CO3 water solution without and with the presence of chloride ions). Copper wire produced by dip-forming method was cold worked to the deformation degrees of 83 %, 87 %, 91 %, 95 % and 99 %. Electrochemical potentiodynamic method was used to investigate corrosion behavior of these wires in alkaline solutions. Open circuit potentials as well as peak potentials are given as a function of deformation degree in both the Na2CO3 pure solution and solutions containing chloride ions.

Chemical Industry, 2009

The Au-In-Sb system belongs to the group of potential candidates for new lead-free solder materia... more The Au-In-Sb system belongs to the group of potential candidates for new lead-free solder materials. Therefore, a lot of investigations concerning its phase diagram and thermodynamic, mechanical, physical characteristics are going on at the moment. Having in mind the significance of such materials application in electronics, it is also very important to study their electrochemical characteristics. In order to give such a characterization, the results of cyclic voltammetry measurements for some alloys in the Au-In-Sb system are presented in this paper.

Proceedings of International Conference on Renewable Electrical Power Sources - MKOIEE 6, 2018

"Dimensions reflected - MoNGeometrija 2020", 2020

This project reveals surveying data and architectural design of the major church in the Studenica... more This project reveals surveying data and architectural design of the major church in the Studenica monastery complex in Serbia reflected in a variety of 3D models and the analysis of the church interior and exterior. Architecture-driven computational parametric modeling was done by using two types of data: close range photogrammetry and high precision laser scanning. The modeling, based on geometric parameters and other planimetric and volumetric analysis, is devised during the four-year study as part of the project Parametric Research of the Studenica Church, a UNESCO Heritage Site, as a Model for Advanced Studies of Medieval Architecture. These models allow for better understanding and representation of the proportional, aesthetic and illumination qualities of the Studenica church and for prototyping procedures for examining other medieval domed churches where we lack more detailed references about their architectural design.

Today generators based on vacuum tubes (VT) are used for high-frequency wood drying. Such systems... more Today generators based on vacuum tubes (VT) are used for high-frequency wood drying. Such systems are robust, reliable, energy efficient and economically acceptable. Their development, and in particular the optimization, are by far more complex than the transistor systems, so that development is now compelled to rely on computer modeling and simulation. For the purposes of this research, the HF generator of 20 kW output power was developed based on VT. A prototype was made and tested in real-life conditions.

Data Control and Control Systems (SCADA) provide automated control and remote monitoring of real ... more Data Control and Control Systems (SCADA) provide automated control and remote monitoring of real world processes and are widely used in electric power systems. These systems are directly managing and monitoring very complex processes of critical infrastructure. Most often they interconnect and form an industrial or SCADA network. This network, as such, is limited to exposure to the outside world. In such circumstances, SCADA systems were not viewed from the aspect of the Cyber Security as a possible serious threat. However, with the rapid development of Information and communication technology (ICT), there was a need to connect business ICT systems with industrial control systems, as well as interconnecting industrial control systems on the principles of ICT and the creation of large control systems, the general commercial name "Distributed Control System" (DCS). This change has led SCADA systems to become vulnerable to cyber attacks. Consequently, it has become necessary ...

Developed countries of Europe are heavily investing in the development and manufacture of equipme... more Developed countries of Europe are heavily investing in the development and manufacture of equipment in the field of renewable energy. Mass production has led to a significant drop in the price of basic elements, so the exploitation of those systems is available to a wider audience, in both developed and developing countries, such as Serbia. World and European planning documents and convention obliges states to reach a significant level of OIEE participation, so the energy policy in that regard adjusts. What follows is a brief survey of the situation in Serbia and Europe.

CORROSION, 2012

The electrochemical behavior of AgCu alloy (50 mass% Ag + 50 mass% Cu) has been investigated usin... more The electrochemical behavior of AgCu alloy (50 mass% Ag + 50 mass% Cu) has been investigated using cyclic voltammetry and the potentiostatic method in 0.1 mol/dm 3 sodium hydroxide (NaOH) solution containing Clions in different concentrations. On the cyclic voltammograms recorded in 0.1 mol dm-3 NaOH solution in the absence of Clions, six anodic current peaks can be noticed at the anodic part, while there are six cathodic and one additional anodic current peak at the cathodic part. In the presence of chloride ions with Clconcentrations higher than 0.001 mol dm-3 , an additional current peak appears ascribed to the formation of silver chloride (AgCl), while current waves of formed copper chlorides are very similar to the ones of copper oxides and can only be noticed by the change in the altitude of peaks. Linear dependence between current density peak and square root of the potential scan rate show that ongoing processes are under diffusion control. According to potentiostatic curves recorded on peak potentials, it has been concluded that with the increase of Clion concentration in solution, the value of stationary curve density is growing unequally and results with the appearance of three regions with different slopes on the curve log j = f (log C Cl-).

CORROSION, 2010

The CuAg4at% alloy exhibits the anneal-hardening effect, which has been seen in previous investig... more The CuAg4at% alloy exhibits the anneal-hardening effect, which has been seen in previous investigations in both cast and sintered CuAg4at% alloys. The goal of this work was to study corrosion properties of the cast alloy in different stages of its synthesis and thermomechanical treatment. The electrodes, made of pure metals, were examined under the same conditions. On the voltammograms recorded in alkaline solution, six current waves can be noticed in the anodic part as well as in the cathodic part. A possible electrochemical reaction is attributed to each wave. After the 60% deformation degree, the alloy becomes more corrosion-resistant and some of the current waves present in the voltammograms obtained before cold-rolling are hardly noticeable here. Further annealing of the deformed alloy at 260°C for 90 min leads to the hardening effect. At the same time, the alloy becomes less corrosion-resistant and all six current waves are noticeable. The subsequent 30-min annealing at 600°C leads to a further decrease of corrosion resistance.

U ovom radu su praćeni efekti toplote hidratacije različitih betona upotrebom termovizijske kamer... more U ovom radu su praćeni efekti toplote hidratacije različitih betona upotrebom termovizijske kamere i termodavača priključenih na osmokanalni sistem za monitoring temperature na bazi PC i LabVIEW paketa, razvijen za potrebe ovog istraživanja. Temperatura ambijenta (laboratorije) beležena je i memorisana pomoću posebnog digitalnog instrumenta. Praćenje temperature svežeg betona je trajalo 24h. Vršena su poređenja temperatura površine izmerenih termodavačima i termovizijskom kamerom. Na osnovu toga uspostavljene su korelaciju koje bi mogle dovesti do pojednostavljenja daljih ispitivanja, posebno masovnih

This paper describes a realization of a bipolar current source developed by the paper authors. Th... more This paper describes a realization of a bipolar current source developed by the paper authors. The source is intended for the application in galvanic and other industrial plants where pulse-reverse current supply is required (with the desired shape in time). A prototype of the device which provides the outcome current intensity up to ± 50 A, has been constructed. The hardware of the source consists of a PC Pentium IV, a commercial ADDA converter, an interface of authors' original construction as well as a current regulator. The application software is developed using a commercial packet LabView as the basis.

The history of gold deposition began in the early nineteenth century when many art objects were e... more The history of gold deposition began in the early nineteenth century when many art objects were electroplated with gold. It has been traced to the early work of Brugnatelli in 1805. Goldelectroplating formulations based on the double salt gold potassium cyanide was patented in 1840. Since then, gold has been plated from cyanide electrolytes, where (Au + ) is ligated with cyanide (CN - ).With regard to the two main disadvantages of cyanide electrolytes, toxicity and risks for technical personnel, there is a trend for using non-cyanide electrolytes. This article is an overview of the historyof gold coatings and investigations of gold complex based on mecaptotriazole.

Copper and brass, among others, are used in the processing industry, for heat exchangers, various... more Copper and brass, among others, are used in the processing industry, for heat exchangers, various fittings and connectors for water industry, pressure regulators, valves for bottles, parts for PPR fittings, contact blades, manometers, and others. Copper and brass are materials of widespread use for plumbing, hot water and electrical installations. However, regardless of their good corrosion properties, brass corrodes in water and the increased concentration of CO2 increases corrosion. The paper presents the application of lasers for the cleaning of copper and brass after exposure to corrosion. Nd: YAG laser with 1064nm wavelength, a pulse duration of 8ns and a pulse frequency of 20 Hz was used. The obtained results were taken with a light microscope, a spectrophotometer and a scanning electron microscope. The results were discussed and compared to the condition before the laser interaction.

Testiranje superkondenzatora due to the high capacitance, and therefore time constants, zahteva p... more Testiranje superkondenzatora due to the high capacitance, and therefore time constants, zahteva prilične modifikacije i prilagođavanje elektrohemijskih metoda i instrumentalnih tehnika. Ovaj rad obezbeđuje matematičku analizu koja definiše parametre eksperimentalnih metoda (galvanostatska metoda, potenciostatska metoda i ciklična voltametrija). Ključne reči: superkondezatori; elektrohemijske metode; matematički model; ekvivalentno električno kolo Testing supercapacitors due to the high capacitance, and therefore time constants, requires considerable modification and adaptation of classical electrochemical methods and instrumental techniques. This paper provides the mathematical analysis which defines the parameters of the experimental methods (galvanostatic method, potentiostatic method and cycling voltammetry).

International Journal of Electrochemical Science, 2021

In this paper, a computer-controlled voltage and current source, together with a response monitor... more In this paper, a computer-controlled voltage and current source, together with a response monitoring system for electrochemical investigations, is presented. The measuring system consisted of two major parts: the measuring hardware (HW) and the proprietary software. The hardware included the data acquisition USB card NI USB 6211 from National Instruments Company as well as all needed circuits (the analogue front end, the signal conditioning circuits, and power supplies). The software is based on the LabVIEW platform from National Instruments, and it is designed to control the signal generation and measurements, to cancel the noise in the signals, and to calibrate the device. The supported electrochemical methods are potential, potentiostatic and galvanostatic measurements, as well as the cyclic voltammetry and impedance measurments. The system was thoroughly tested, and it was determined that the system characteristics fulfil the requirements for most of the electrochemical and bioelectrochemical measurements, supercapacitor characteristics investigations, and much more. The overall system is modular; the HW and SW can easily be upgraded to support different methods and purposes and, therefore, the performance of the system.

International Journal of Materials Research, 2018

Pulse-reverse power modes are used in galvanotechniques in order to obtain coatings with better c... more Pulse-reverse power modes are used in galvanotechniques in order to obtain coatings with better characteristics in terms of gloss, adhesion, tracking sharp edges and uniform distribution of deposits on complex shape objects, compared with the coatings produced by constant current modes. Pulse-reverse modes also allow the use of a higher current density, and thus the production speed of electroplating cells increases. Systems for standard electroplating of copper, silver and gold are optimised by the suitable choice of duration and intensity of the pulses. It is shown that coatings with satisfactory quality can be deposited using higher current density, different modes of pulsed current in a very short period of time, without expensive and often dangerous additives in the electrolyte. Parameters of the model for certain electrochemical systems were determined by modelling and computer simulation, so the system behaviour under different circumstances becomes predictive.

2016 International Conference on Electronics and Information Technology (EIT), 2016

The paper gives a brief overview of computer controlled thermogravimetric analysis system. The sy... more The paper gives a brief overview of computer controlled thermogravimetric analysis system. The system consists of a personal computer, software, data acquisition card and interface for the provision of the necessary conditions for the analysis and adaptation of input and output signals. The entire control system, as well as the acquisition, recording and processing of measured data is solved by software. Application is based on programming package LabView.

Chemical Industry, 2009

The results of an attempt in using cyclic voltammetry for characterization of gold, silver, coppe... more The results of an attempt in using cyclic voltammetry for characterization of gold, silver, copper and 18-k gold alloys by their anodic behavior in 1 mol/dm3 H2SO4 are presented in this paper. Gold alloys containing 75 mass% Au are named as 18-k gold, but it is usually three component alloy containing 75 mass% Au, 12.5 mass% Ag and 12.5 mass% Cu as the main components. Investigated alloys were obtained by melting powders of pure metals mixed in corresponding ratio, casting, cooling in air, rolling and drawing in the wire shape. To achieve the required mechanical properties, the alloys had heat-treated three times. Each alloy exhibits characteristic current peaks on voltammogram that can be used to recognize the kind of present alloying metal in gold. Also, the content of the alloying metal can be roughly estimated from the peak value of current densities.

Chemical Industry, 2007

This paper describes an electrochemical research system based on the Lab VIEW computer software p... more This paper describes an electrochemical research system based on the Lab VIEW computer software package. An overview of well known electrochemical methods, such as potential measurements, chronopotentiometry, chronoamperometry, cyclic voltammetry and EIS is given. Electrochemical impedance spectroscopy has been adapted for systems containing large capacitances. For signal generation and recording of the response of the investigated electrochemical cell, a measurement and control system was developed, based on a PC P4 computer. The rest of the hardware consists of a commercially available AD-DA converter and an external interface for analog signal processing. The interface is a result of the authors own research. The software platform for the desired measurement methods is Lab VIEW package, which is regarded as a high standard in the area of modern virtual instruments. The developed system was adjusted, tested and compared with other commercially available systems. One such system is...

The corrosion behavior of copper was investigated by a constant sweep rate (0.01 V/s) and in diff... more The corrosion behavior of copper was investigated by a constant sweep rate (0.01 V/s) and in different corrosion media (1 M Na2CO3 water solution without and with the presence of chloride ions). Copper wire produced by dip-forming method was cold worked to the deformation degrees of 83 %, 87 %, 91 %, 95 % and 99 %. Electrochemical potentiodynamic method was used to investigate corrosion behavior of these wires in alkaline solutions. Open circuit potentials as well as peak potentials are given as a function of deformation degree in both the Na2CO3 pure solution and solutions containing chloride ions.

Chemical Industry, 2009

The Au-In-Sb system belongs to the group of potential candidates for new lead-free solder materia... more The Au-In-Sb system belongs to the group of potential candidates for new lead-free solder materials. Therefore, a lot of investigations concerning its phase diagram and thermodynamic, mechanical, physical characteristics are going on at the moment. Having in mind the significance of such materials application in electronics, it is also very important to study their electrochemical characteristics. In order to give such a characterization, the results of cyclic voltammetry measurements for some alloys in the Au-In-Sb system are presented in this paper.

Proceedings of International Conference on Renewable Electrical Power Sources - MKOIEE 6, 2018

"Dimensions reflected - MoNGeometrija 2020", 2020

This project reveals surveying data and architectural design of the major church in the Studenica... more This project reveals surveying data and architectural design of the major church in the Studenica monastery complex in Serbia reflected in a variety of 3D models and the analysis of the church interior and exterior. Architecture-driven computational parametric modeling was done by using two types of data: close range photogrammetry and high precision laser scanning. The modeling, based on geometric parameters and other planimetric and volumetric analysis, is devised during the four-year study as part of the project Parametric Research of the Studenica Church, a UNESCO Heritage Site, as a Model for Advanced Studies of Medieval Architecture. These models allow for better understanding and representation of the proportional, aesthetic and illumination qualities of the Studenica church and for prototyping procedures for examining other medieval domed churches where we lack more detailed references about their architectural design.

Today generators based on vacuum tubes (VT) are used for high-frequency wood drying. Such systems... more Today generators based on vacuum tubes (VT) are used for high-frequency wood drying. Such systems are robust, reliable, energy efficient and economically acceptable. Their development, and in particular the optimization, are by far more complex than the transistor systems, so that development is now compelled to rely on computer modeling and simulation. For the purposes of this research, the HF generator of 20 kW output power was developed based on VT. A prototype was made and tested in real-life conditions.

Data Control and Control Systems (SCADA) provide automated control and remote monitoring of real ... more Data Control and Control Systems (SCADA) provide automated control and remote monitoring of real world processes and are widely used in electric power systems. These systems are directly managing and monitoring very complex processes of critical infrastructure. Most often they interconnect and form an industrial or SCADA network. This network, as such, is limited to exposure to the outside world. In such circumstances, SCADA systems were not viewed from the aspect of the Cyber Security as a possible serious threat. However, with the rapid development of Information and communication technology (ICT), there was a need to connect business ICT systems with industrial control systems, as well as interconnecting industrial control systems on the principles of ICT and the creation of large control systems, the general commercial name "Distributed Control System" (DCS). This change has led SCADA systems to become vulnerable to cyber attacks. Consequently, it has become necessary ...

Developed countries of Europe are heavily investing in the development and manufacture of equipme... more Developed countries of Europe are heavily investing in the development and manufacture of equipment in the field of renewable energy. Mass production has led to a significant drop in the price of basic elements, so the exploitation of those systems is available to a wider audience, in both developed and developing countries, such as Serbia. World and European planning documents and convention obliges states to reach a significant level of OIEE participation, so the energy policy in that regard adjusts. What follows is a brief survey of the situation in Serbia and Europe.

CORROSION, 2012

The electrochemical behavior of AgCu alloy (50 mass% Ag + 50 mass% Cu) has been investigated usin... more The electrochemical behavior of AgCu alloy (50 mass% Ag + 50 mass% Cu) has been investigated using cyclic voltammetry and the potentiostatic method in 0.1 mol/dm 3 sodium hydroxide (NaOH) solution containing Clions in different concentrations. On the cyclic voltammograms recorded in 0.1 mol dm-3 NaOH solution in the absence of Clions, six anodic current peaks can be noticed at the anodic part, while there are six cathodic and one additional anodic current peak at the cathodic part. In the presence of chloride ions with Clconcentrations higher than 0.001 mol dm-3 , an additional current peak appears ascribed to the formation of silver chloride (AgCl), while current waves of formed copper chlorides are very similar to the ones of copper oxides and can only be noticed by the change in the altitude of peaks. Linear dependence between current density peak and square root of the potential scan rate show that ongoing processes are under diffusion control. According to potentiostatic curves recorded on peak potentials, it has been concluded that with the increase of Clion concentration in solution, the value of stationary curve density is growing unequally and results with the appearance of three regions with different slopes on the curve log j = f (log C Cl-).

CORROSION, 2010

The CuAg4at% alloy exhibits the anneal-hardening effect, which has been seen in previous investig... more The CuAg4at% alloy exhibits the anneal-hardening effect, which has been seen in previous investigations in both cast and sintered CuAg4at% alloys. The goal of this work was to study corrosion properties of the cast alloy in different stages of its synthesis and thermomechanical treatment. The electrodes, made of pure metals, were examined under the same conditions. On the voltammograms recorded in alkaline solution, six current waves can be noticed in the anodic part as well as in the cathodic part. A possible electrochemical reaction is attributed to each wave. After the 60% deformation degree, the alloy becomes more corrosion-resistant and some of the current waves present in the voltammograms obtained before cold-rolling are hardly noticeable here. Further annealing of the deformed alloy at 260°C for 90 min leads to the hardening effect. At the same time, the alloy becomes less corrosion-resistant and all six current waves are noticeable. The subsequent 30-min annealing at 600°C leads to a further decrease of corrosion resistance.