Electrochemical and surface characterization of ternary alloys of the system Ag-Cu-Zn in near neutral chloride solutions.

Predmet istraživanja disertacije bile su legure sistema Ag-Cu-Zn sličnog sastava faza u širokom opsegu sadržaja srebra. Metali za sve ispitivane legure dobijeni su reciklažom elektronskog otpada. Nakon dobijanja dvostrukim topljenjem i homogenizacionog žarenja u trajanju od 24h u atmosferi azota izvršena je površinska i elektrohemijska karakterizacija ovih legura. Kao legure za uporednu analizu korišene su legure sistema Ag-Zn i Cu-Zn, sastava sličnog fazama ispitivanih legura i legura Ag40Cu30Zn30 čiji se fazni sastav značajno razlikuje od preostale tri trokomponentne legure istog sistema. Termodinamička analiza Ag-Cu-Zn sistema izvršena je korišćenjem faznih dijagrama i Pandat softvera. Za površinsku karakterizaciju homogenizovanih legura korišćena je skenirajuća elektronska mikroskopija sa rentgenskom analizom (SEM/EDS) i rentgenskom difrakcijom (XRD). Elektrohemijsko ponašanje legura sistema Ag-Cu-Zn ispitivano je u deaerisanim i prirodno aerisanim neutralnim rastvorima NaCl koncentracije 3,5% (masenih), sintetičkoj morskoj vodi, prirodnim filtriranim morskim vodama i boratnom puferu (pH=8.1) sa (masenih) 3,5% NaCl, korišćenjem potenciodinamičkih merenja, linearne polarizacije, ciklične voltametrije i potenciostatskih merenja. Anodni film formiran na ispitivanim legurama hronoampermetrijski na 0,0 V i +0,25 V (vs. ZKE) je ispitivan: rentgenskom difrakcijom, FE SEM/EDS metodom, Raman spektroskopijom i MALDI masenom spektrometrijom. Utvrđen je isti mehanizam korozije prilikom anodne polarizacije za sve legure u svim hloridnim rastvorima, osim u puferisanom rastvoru NaCl. Naročito je slično ponašanje legura Ag43Cu37Zn20 i Ag25Cu52,5Zn22,5. Legura sa 25% (mas.) srebra ima sličnu otpornost na koroziju u 3,5% rastvoru NaCl kao legura sa 40% (mas.) srebra, što je nedvosmisleno uticaj faznog sastava. Pri sličnom faznom sastavu legura koroziona otpornost raste sa većim udelom srebra (faze bogate srebrom). Sve ispitivane legure sistema Ag-Cu-Zn nemaju pasivnu oblast u svim rastvorima osim puferskog, gde se javlja pseudo-pasivna oblast na polarizacionim krivama...Alloys of the Ag-Cu-Zn system with wide range of silver content, selected to have similar phase compositions, were the subject of the research. Metals for all examined alloys are obtained by recycling of electronic waste. After obtaining alloys by double melting and homogenization annealing for 24 h under nitrogen, surface and electrochemical characterization of these alloys were performed. For comparative analysis, binary alloys of Ag-Zn and Cu-Zn systems were used. They had similar composition as the phases of the examined alloys. For the same purposes the Ag40Cu30Zn30 alloy with different phase composition than three other alloys of the same system was used. Thermodynamic analysis of the Ag-Cu-Zn system was performed using phase diagrams and Pandat software. Surface characterization of the homogenizated alloys was performed by Scanning Electron Microscopy with X-ray microanalysis (SEM/EDS) and X-diffraction (XRD). Electrochemical behavior of the alloys of the Ag-Cu-Zn system in deaerated and naturally aerated neutral 3.5 wt.% NaCl solution, synthetic seawater, natural filtered seawaters and borate buffer (pH=8.1) with 3,5% NaCl has been investigated using the potentiodynamic measurements, linear polarization, cyclic voltammetry and potentiostatic measurements. The anodic layer formed on examined alloys by chronoamperometry at 0.0 and +0.25 V (vs. SCE) has been characterized by X-ray diffraction, FE SEM/EDS, Raman spectroscopy and MALDI mass spectrometry. The same mechanism of corrosion under anodic polarization was found for all alloys in all chloride solutions except buffered 3.5% NaCl solution. The behavior of alloys Ag43Cu37Zn20 and Ag25Cu52.5Zn22.5 is particularly similar. The alloy with 25 wt. % content of silver has similar corrosion resistance in 3.5% NaCl solution as the alloy with 40 wt. % silver, which is clearly the consequence of phase composition. For a similar phase composition of alloy, corrosion resistance increases with higher content of silver (Ag-rich phase). All investigated alloys of the Ag-Cu-Zn system have no passive area in all solutions, except in buffered solution, where a pseudo-passive area appears on polarization curves. Copper rich phase (Cu) is critical for corrosion resistance of alloys. Preferentially dissolution of this phase is determined by polarization curves analysis, chemical..

Influence of reducing agents and surfactants on size and shape of silver fine powder particles

Silver fine powder with different shapes and sizes were prepared by chemical reduction and characterized by scanning electron microscope. In this paper was presented the method for the preparation of the fine Ag powder with particles size smaller than 2.5 µm with suitability for the mass-production scale. Reduction was performed from nitrate solution directly by vigorous stirring at room temperature by three different reduction agents, with and without presence of two dispersants. Scanning electron microscopy revealed the preferred size of the particles obtained in all experiments with aim of the protecting agent. Larger particles and wider size distribution were obtained without surfactants although with average size of about 1 µm and small quantity of larger clusters of primary particles that is out of the fine powder classification. High purity, 99.999%, of silver was obtained in every experiment.  http://dx.doi.org/10.5937/metmateng1402073

THE INFLUENCE OF RHODIUM CONTENT ON THE MECHANICAL PROPERTIES OF PLATINUM

The paper presents the results of investigation the influence of rhodium as an alloying element on the mechanical properties of platinum. A short-term and tensile strength were tested, at room and high temperatures, and also sliding rate and time to the destruction of the Pt-Rh system alloys at high temperatures. The results showed that alloying with rhodium strengthens the platinum while reducing its plasticity. Time to destruction is much longer in Pt-Rh alloys compared to pure platinum

Prospective of the LDI MS to characterization the corrosion products of silver-copper alloys on an example of the Ag-Cu-X (X- Zn, Pd, In) system

This work presents the perspective of applying the laser desorption/ionization mass spectrometry (LDI MS) for characterization the anode film of the Ag60Cu26Zn14, Ag58.5Cu31.5Pd10, and Ag63Cu27In10 alloys (at high concentrations of chloride ions in solutions). The reference LDI mass spectra of anode films of pure Ag and Cu have been used for the identification of product corrosion. Knowing the clusters detected in the reference spectra lead to the facilitating identification of the LDI mass spectrum of the sample and reduces the analysis time. The LDI MS analysis of these alloys revealed that the predominant corrosion product are AgCl (from AgnCln+1−/+, n = 1–3), and CuCl (from “superhalogen” CumCln− clusters, m = 1–2, n = 2–6); it also revealed Cu2(OH)3Cl (from Cu2(OH)(H2O)2+) and Cu2O (from Cu(H2O)+, Cu2O doped with chlorine). These results are in accordance with the X-ray diffraction and Raman analysis. The LDI MS spectra of alloys contain the additional peaks formed due to the mutual influences of different metals in the alloys (AgCuCl3− (AgCl-CuCl2−), AgCu2Cl4− (AgCl-CuCl-CuCl2−), and Ag2CuCl4− (AgCl-AgCl-CuCl−), which is consistent with the identified corrosion products. It should be noted that the LDI MS suggest the presence of CuCl2, which can be interpreted as the corrosion products retained in the porous films of alloys, and not detected by the other methods due to a small amount. The future theoretical and experimental studies of metal clusters, significant for metallurgy, can contribute that the LDI MS is becoming a powerful analytical tool for characterization the metal surfaces

Mechanical Properties of Electrolytically Produced Copper Coatings Reinforced with Pigment Particles

Copper from sulfate baths without and with added inorganic pigment particles based on strontium aluminate doped with europium and dysprosium (SrAl2O4: Eu2+, Dy3+) was electrodeposited on a brass cathode by a galvanostatic regime. Morphological, structural, and roughness analysis of the pigment particles, the pure (pigment-free) Cu coating, and the Cu coatings with incorporated pigment particles were performed using SEM, XRD, and AFM techniques, respectively. Hardness and creep resistance were considered for the examination of the mechanical properties of the Cu coatings, applying Chicot–Lesage (for hardness) and Sargent–Ashby (for creep resistance) mathematical models. The wettability of the Cu coatings was examined by the static sessile drop method by a measurement of the water contact angle. The incorporation of pigment particles in the Cu deposits did not significantly affect the morphology or texture of the coatings, while the roughness of the deposits rose with the rise in pigment particle concentrations. The hardness of the Cu coatings also increased with the increasing concentration of pigments and was greater than that obtained for the pigment-free Cu coating. The presence of the pigments caused a change in the wettability of the Cu coatings from hydrophilic (for the pigment-free Cu coating) to hydrophobic (for Cu coatings with incorporated particles) surface areas

Recikliranje metala iz obnovljivih izvora energije u legure koje se koriste u zelenim energijama

Recycling specific e-waste from renewable energy provides an opportunity to integrate it with a pyrometallurgical production process of various types of non-ferrous alloys. One type of alloy is used for brazing of different types of materials like copper and stainless steel and they are often used for solar collector installations. Other obtained alloys belong to the new type of tarnish-resistant silver alloys that can be used in electronics and various renewable applications. All recycled metals from the process are used for the later ingot metallurgy and could be further processed to obtain these alloys' wire, sheet metal, or other suitable shapes (rods, strips). This study presents the recycling process with the technology parameters and material flowsheets. Special attention in the paper is given to the structure of selected alloys. Optical microscopy, SEM with EDS, and the XRD method were used to characterize the microstructure of the alloys.Reciklaža specifičnog elektronskog otpada iz obnovljivih izvora energije pruža mogućnost da se on integriše sa pirometalurškim proizvodnim procesom različitih vrsta obojenih legura. Jedna vrsta legura se koristi za lemljenje različitih vrsta materijala kao što su bakar i nerđajući čelik i često se koriste za instalacije solarnih kolektora. Ostale dobijene legure pripadaju novom tipu legura srebra otpornih na tamnjenje koje se mogu koristiti u elektronici i raznim aplikacijama obnovljivih izvora energije. Svi reciklirani metali iz procesa se koriste za kasniju ingot metalurgiju i mogu se dalje prerađivati da bi se dobila žica, lim ili drugi odgovarajući oblici (šipke, trake). Ova studija prezentuje proces reciklaže sa tehnološkim parametrima i tokovima materijala. Posebna pažnja u radu je posvećena strukturi odabranih legura. Za karakterizaciju mikrostrukture legura korišćeni su optička mikroskopija, SEM sa EDS-om i XRD metoda

Electrochemical and surface characterization of ternary alloys of the system Ag-Cu-Zn in near neutral chloride solutions.

Predmet istraživanja disertacije bile su legure sistema Ag-Cu-Zn sličnog sastava faza u širokom opsegu sadržaja srebra. Metali za sve ispitivane legure dobijeni su reciklažom elektronskog otpada. Nakon dobijanja dvostrukim topljenjem i homogenizacionog žarenja u trajanju od 24h u atmosferi azota izvršena je površinska i elektrohemijska karakterizacija ovih legura. Kao legure za uporednu analizu korišene su legure sistema Ag-Zn i Cu-Zn, sastava sličnog fazama ispitivanih legura i legura Ag40Cu30Zn30 čiji se fazni sastav značajno razlikuje od preostale tri trokomponentne legure istog sistema. Termodinamička analiza Ag-Cu-Zn sistema izvršena je korišćenjem faznih dijagrama i Pandat softvera. Za površinsku karakterizaciju homogenizovanih legura korišćena je skenirajuća elektronska mikroskopija sa rentgenskom analizom (SEM/EDS) i rentgenskom difrakcijom (XRD). Elektrohemijsko ponašanje legura sistema Ag-Cu-Zn ispitivano je u deaerisanim i prirodno aerisanim neutralnim rastvorima NaCl koncentracije 3,5% (masenih), sintetičkoj morskoj vodi, prirodnim filtriranim morskim vodama i boratnom puferu (pH=8.1) sa (masenih) 3,5% NaCl, korišćenjem potenciodinamičkih merenja, linearne polarizacije, ciklične voltametrije i potenciostatskih merenja. Anodni film formiran na ispitivanim legurama hronoampermetrijski na 0,0 V i +0,25 V (vs. ZKE) je ispitivan: rentgenskom difrakcijom, FE SEM/EDS metodom, Raman spektroskopijom i MALDI masenom spektrometrijom. Utvrđen je isti mehanizam korozije prilikom anodne polarizacije za sve legure u svim hloridnim rastvorima, osim u puferisanom rastvoru NaCl. Naročito je slično ponašanje legura Ag43Cu37Zn20 i Ag25Cu52,5Zn22,5. Legura sa 25% (mas.) srebra ima sličnu otpornost na koroziju u 3,5% rastvoru NaCl kao legura sa 40% (mas.) srebra, što je nedvosmisleno uticaj faznog sastava. Pri sličnom faznom sastavu legura koroziona otpornost raste sa većim udelom srebra (faze bogate srebrom). Sve ispitivane legure sistema Ag-Cu-Zn nemaju pasivnu oblast u svim rastvorima osim puferskog, gde se javlja pseudo-pasivna oblast na polarizacionim krivama...Alloys of the Ag-Cu-Zn system with wide range of silver content, selected to have similar phase compositions, were the subject of the research. Metals for all examined alloys are obtained by recycling of electronic waste. After obtaining alloys by double melting and homogenization annealing for 24 h under nitrogen, surface and electrochemical characterization of these alloys were performed. For comparative analysis, binary alloys of Ag-Zn and Cu-Zn systems were used. They had similar composition as the phases of the examined alloys. For the same purposes the Ag40Cu30Zn30 alloy with different phase composition than three other alloys of the same system was used. Thermodynamic analysis of the Ag-Cu-Zn system was performed using phase diagrams and Pandat software. Surface characterization of the homogenizated alloys was performed by Scanning Electron Microscopy with X-ray microanalysis (SEM/EDS) and X-diffraction (XRD). Electrochemical behavior of the alloys of the Ag-Cu-Zn system in deaerated and naturally aerated neutral 3.5 wt.% NaCl solution, synthetic seawater, natural filtered seawaters and borate buffer (pH=8.1) with 3,5% NaCl has been investigated using the potentiodynamic measurements, linear polarization, cyclic voltammetry and potentiostatic measurements. The anodic layer formed on examined alloys by chronoamperometry at 0.0 and +0.25 V (vs. SCE) has been characterized by X-ray diffraction, FE SEM/EDS, Raman spectroscopy and MALDI mass spectrometry. The same mechanism of corrosion under anodic polarization was found for all alloys in all chloride solutions except buffered 3.5% NaCl solution. The behavior of alloys Ag43Cu37Zn20 and Ag25Cu52.5Zn22.5 is particularly similar. The alloy with 25 wt. % content of silver has similar corrosion resistance in 3.5% NaCl solution as the alloy with 40 wt. % silver, which is clearly the consequence of phase composition. For a similar phase composition of alloy, corrosion resistance increases with higher content of silver (Ag-rich phase). All investigated alloys of the Ag-Cu-Zn system have no passive area in all solutions, except in buffered solution, where a pseudo-passive area appears on polarization curves. Copper rich phase (Cu) is critical for corrosion resistance of alloys. Preferentially dissolution of this phase is determined by polarization curves analysis, chemical..

E-scrap processing: Theory and practice

The importance of recycling the waste electrical and electronic equipment (WEEE), in recent years, has been taken into increasing concern and consideration not only by the government, but also by their hazardous material contents. Electronic waste can be defined as a mixture of various metals, particularly copper, aluminum and steel, with various types of plastics and ceramics. Recycling of electronic waste is an important subject not only from the point of waste treatment, but also from the recovery aspect of valuable materials. Pyrometallurgical processing has been a traditional technology for recovery of the precious metals from waste electronic equipment. In the past two decades, the most active research area on recovery of metals from electronic scraps is recovering the precious metals using the hydrometallurgical techniques. Compared with the pyrometallurgical processing, the hydrometallurgical method is more exact, more predictable and more easily controlled. In the last decade, the recovery of metals by biotechnology has been one of the most promising technologies. Biometallurgy has the potential for a major technology breakthrough for the materials and minerals industry due to a great interest shown by the major international companies for this new technology. Understanding the biochemical processes, involved in treatments of metals, has been the subject to growing investigations for the last 20 years. At present, the research and development are in progress for a number of metals such as copper, nickel, cobalt, zinc, gold and silver. However, the activity of leaching bacteria is applied for recovery of gold and silver only to remove the interfering metal sulfides from ore bearing the precious metals prior to the cyanidation treatment. Recent research trend is to use the combined methods for optimal results

Prezentacija softvera za primenu simpleks metoda

This paper presents original software, developed for the needs of mathematical modeling of complex processes using the simplex method. The software was developed in the Delphi programming language for the Windows environment. The idea was to use the developed software to determine the efficiency of the simplex method in choosing the optimal mode of heat treatment of PdNi5 alloy, and simplex triangle can visually monitor the legality of the behavior of the test process depending on the influential parameters.U radu je predstavljen originalni softver, razvijen za potrebe matematičkog modeliranja složenih procesa primenom simpleks metode. Softver je razvijen u programskom jeziku Delphi za Vindovs okruženje. Ideja je bila da se razvijenim softverom utvrdi efikasnost simpleks metode u izboru optimalnog načina termičke obrade legure PdNi5, a simpleks trouglom se može vizuelno pratiti zakonitost ponašanja procesa ispitivanja u zavisnosti od uticajnih parametara