Vesna Grekulović

University of Belgrade

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Mirjana Rajčić-Vujasinović

University of Belgrade

Zoran Stević

University of Belgrade

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Nada Štrbac

University of Belgrade

Milica Zdravković

University of Belgrade

Aleksandra Mitovski

University of Belgrade

Ivana Marković

University of Belgrade

Milan Gorgievski

University of Belgrade

Miljan Marković

University of Belgrade

Uroš Stamenković

University of Belgrade

Kristina Božinović

University of Belgrade

Cooperative Institutions

University of Belgrade

Mining and Metallurgy Institute Bor

Institute for Technology of Nuclear and other Mineral Raw Materials

University of Prishtina

Institute of Metallurgy

Institute of Chemistry, Technology and Metallurgy

University of Zagreb

Institut za savremenu istoriju

Academy of Engineering Sciences of Serbia

University of Idaho

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Electrochemical behavior of alloy AgCu50 during oxidation in the presence of chlorides and benzotriazole

Materials Testing (2017)

Mirjana Rajčić-Vujasinović Vesna Grekulović Uroš Stamenković Zoran Stević

Abstract The presence of chloride ions in concentrations higher than 0.01 mol × dm −3 significantly intensifies anodic processes at AgCu50 alloy. In order to slow down this reaction, it was looked for the possibility of using benzotriazole known as an effective corrosion inhibitor for copper. This paper shows the influence of benzotriazole in a wide range of concentrations on inhibition of anodic processes as well as its influence on mechanism of the reactions such as formation of copper and silver oxides and chlorides. To determine this influence, open circuit potential measurements, anodic polarization and potentiostatic oxidation followed by optical microscopy were used. It was discovered that benzotriazole in concentrations higher than 0.005 mol × dm −3 almost completely passivates the mentioned alloy in alkaline solutions in the presence of chloride ions in a concentration range from 0.01 to 0.02 mol × dm −3 .

Benzotriazole

10.3139/120.111040

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Citations (1)

Posibilidades de reutilización de la chatarra de acero para la obtención de cuchillas para cortar

Revista de Metalurgia (2017)

Nada Štrbac Ivana Marković Aleksandra Mitovski Ljubiša Balanović Dragana Živković

El trabajo presenta los resultados de la caracterización de diversos tipos de aceros que han llegado al final de su ciclo de vida útil, y de los que se desconocía su composición química, propiedades mecánicas y tratamiento termomecánico aplicado previamente. El estudio se realizó con el objetivo de analizar las posibilidades de reutilización de algunos de estos materiales en aplicaciones agrícolas e industriales, obteniendo hojas de corte. Las formas exigidas a las hojas de corte se consiguieron aplicando diversos tipos de tratamientos termomecánicos. El análisis químico de la chatarra de acero de acero se realizó utilizando Energías Dispersivas de Rayos X. La microestructura se estudió utilizando Microscopía Óptica y Microscopía Electrónica de Barrido. La dureza de la chatarra de acero y de las cuchillas obtenidas se midió utilizando la escala Rockwell C. Los valores de dureza de las cuchillas obtenidas indican una buena selección de los productos finales de acero.

10.3989/revmetalm.086

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Reaction mechanism and kinetics of sulfide copper concentrate oxidation at elevated temperatures

Metallurgical and Materials Engineering (2017)

Aleksandra Mitovski Nada Štrbac Miroslav Sokić Milan Kragović Vesna Grekulović

Sulfide copper concentrate from domestic ore deposit (Bor, Serbia) was subjected to oxidation in the air atmosphere due to a better understanding of reaction mechanism and oxidation of various sulfides present in the copper concentrate at elevated temperatures. Results of the initial sample characterization showed that concentrate is chalcopyrite–enargite-tennantite type, with an increased arsenic content. Characterization of the oxidation products showed the presence of sulfates, oxysulfates, and oxides. Based on predominance area diagrams for Me-S-O systems (Me = Cu, Fe, As) combined with thermal analysis results, the reaction mechanism of the oxidation process was proposed. The reactions which occur in the temperature range 25 – 1000 °C indicate that sulfides are unstable in the oxidative conditions. Sulfides from the initial sample decomposed into binary copper and iron sulfides and volatile arsenic oxides at lower temperatures. Further heating led to oxidation of sulfides into iron oxides and copper sulfates and oxysulfates. At higher temperatures sulfates and oxysulfates decomposed into oxides. Kinetic analysis of the oxidation process was done using Ozawa’s method in the non-isothermal conditions. The values for activation energies showed that the reactions are chemically controlled and the temperature is the most influential parameter on the reaction rates.

Copper sulfide

Isothermal process

Iron sulfide

10.30544/320

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Citations (6)

Electrochemical behavior of Ag-Cu alloy in alkaline media

Hemijska industrija (2010)

Vesna Grekulović Mirjana Rajčić-Vujasinović Zoran Stević

Results of the investigation of electrochemical behaviour of Ag-Cu alloy containing 50 mass% Ag and 50 mass% Cu are presented in this paper. Pure silver and copper were investigated, too. Working electrodes were prepared by metallurgical process. 1 mol dm-3 and 0.5 mol dm-3 solutions of NaOH are chosen as the electrolyte. On the cyclic voltammograms, some current waves corresponding to number and quantity of phases present in the investigated electrodes appeared and they can be used for characterization of investigated alloy. On the voltammogram recorded for pure silver, two anodic and two cathodic peaks appeared. First peak consisted of two joined current waves which can be ascribed to the formation of the two different types of silver(I) oxide, Ag2O. Second peak should correspond to the formation of silver(II) oxide, AgO. Voltammogram obtained for pure copper exhibits one broad current wave corresponding to the formation of copper oxides, followed by a wide potential area in which copper is completely passive. At 0.4 V vs. SCE, current starts to increase again due to oxygen evolution and probably due to simultaneous dissolution of copper with formation of CuO22- as a product. In alkaline solutions copper has no significant influence on the shape and current values of the voltammograms recorded for Ag-Cu alloy; however, it has an influence only on the anodic and cathodic peak potentials, which are shifted to more negative values in comparison to Ag. It could mean an easier formation of oxides and their harder reduction. Comparing voltammograms recorded for Ag-Cu alloy in 0.5 moldm-3 NaOH and in 1 moldm-3 NaOH solutions, one can see that current waves appear at more positive potentials on the voltammograms obtained in the solution of lower concentration and with much higher current densities than those on the voltammograms obtained in the solution of higher concentration.

Copper oxide

Silver oxide

10.2298/hemind100114005g

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The influence of novel organic gold complex on photoresist layers of printed circuit boards

Metallurgical and Materials Engineering (2015)

Silvana Dimitrijević Zoran Stević Mirjana Rajčić-Vujasinović Vesna Grekulović Stevan P. Dimitrijević

The goal of this paper was to study the influence of organic gold complex based on mercaptotriazole on photoresist layers used in manufacturing of printed circuit boards (PCBs). Investigations were performed by immersion the previously prepared boards in electrolytes with different pH values (pH=2, 4, 7, 9 and 12) at gold concentration of 2.5 g/dm3 and in gold complexes with different gold concentrations (1.5; 2.0; 2.5; 3.0 and 3.5 g/dm3) at pH value of pH=9. Investigations showed that photoresist layers on boards are the most resistant at optimal operating conditions, pH=9 and concentration of gold of 2.5 g/dm3.

Photoresist

10.30544/73

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Citations (2)

Electrochemical Characterization of a Commercial Au-Ag-Cu Alloy in an Acidic Medium

International Journal of Electrochemical Science (2016)

Vesna Grekulović Mirjana Rajčić-Vujasinović Zoran Stević

The voltammograms obtained by the cyclic voltammetry method show potentials at which current waves occur successively corresponding to the number and the quantity of the phases present in the alloy, which can be used for characterisation of the investigated alloys. All voltammograms for gold and gold containing alloys exhibit anodic waves corresponding to the formation of the first OH monolayer, low and high valence gold oxides or their hydrated forms. A well-defined cathodic wave can be observed indicating gold oxide reduction. In addition, the voltammograms for the gold-copper alloys exhibit the current waves corresponding to the formation of copper oxides in the anodic region and their reduction in the cathodic region. The voltammograms for the gold-silver alloy also contain the current waves indicating oxidation of silver in the anodic region and its reduction in the cathodic region. The electrodes were obtained metallurgically. This paper presents investigation results of the possibility of using cyclic voltammetry to determine the composition of an commercial gold alloy declared as 14-carat gold [58.5 % Au + the most common alloying elements Ag and Cu, in the proportion 1:1] as well as a verification of pure gold declaration.

Gold alloys

10.1016/s1452-3981(23)15834-2

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Citations (3)

Influence of thermo-mechanical treatment on the electrochemical behavior of cast and sintered dilute Cu–Au alloy

Journal of Alloys and Compounds (2020)

Ivana Marković Vesna Grekulović Mirjana Rajčić Vujasinović Srba Mladenović

Open-circuit voltage

Recrystallization (geology)

Hardening (computing)

10.1016/j.jallcom.2020.154726

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The Influence of Benzotriazole on the Electrochemical Behavior of the AgCu50 Alloy in a Chloride Medium

Protection of Metals and Physical Chemistry of Surfaces (2022)

Milica Zdravković Vesna Grekulović Mirjana Rajčić Vujasinović Aleksandra Mitovski Nada Štrbac

Benzotriazole

Open-circuit voltage

10.1134/s2070205122040268

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Citations (1)

Ekstrakt ruzmarina kao ekološki inhibitor korozije bakra u hloridnoj sredini

Ecologica (2021)

Vesna Grekulović Nada Štrbac Aleksandra Mitovski

Sažetak: Zbog široke

10.18485/ecologica.2021.28.102.24

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Study of low-temperature isothermal annealing in the PM Cu-Pt alloys after plastic deformation

Tehnika (2020)

Ivana Marković Marijana Mladenović Svetlana Ivanov D. Gusković Uroš Stamenković

The investigation was performed on pure sintered (PM) copper and dilute PM copper-based alloys with 3 and 5.9 wt.% of platinum. Investigated PM samples were obtained using the standard powder metallurgy technique by mixing the elemental powders in proper ratio followed by pressing in hydraulic press and sintering in a hydrogen atmosphere. The PM samples were further cold deformed by rolling at ambient temperature to a total rolling reduction of 60 %. On pre-deformed samples, the low-temperature isothermal annealing up to the 100 hours was accomplished. During all stages of isothermal annealing, the values of Vickers hardness, micro-hardness, and electrical conductivity were measured. Also, the microstructure was analyzed using the scanning electron microscopy (SEM). This investigation has shown a slight increase in all measured properties for both dilute Cu-Pt alloys. An increase in mechanical properties was some more pronounced for more alloyed Cu-5.9wt%Pt alloy. During the low-temperature isothermal annealing, there were no significant changes in properties for pure pre-deformed copper.

Isothermal process

Powder Metallurgy

Vickers hardness test

10.5937/tehnika2003313m

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