Aluminum/zirconium alloys obtained by Al underpotential deposition onto Zr from low temperature AlCl3+NaCl molten salts

Contrary to the widely accepted hypothesis that it is not possible, aluminum underpotential deposition (UPD) onto zirconium from a low temperature (200, 250 and 300 °C) equimolar chloroaluminate melt was recorded. Furthermore, it was shown that aluminum UPD facilitates alloy formation between the deposited aluminum monolayer and the zirconium substrate by interdiffusion. The aluminum/zirconium alloys formed at temperatures substantially lower than those needed for thermal preparation of the same alloys were Al3Zr2 and Al3Zr. The experimental techniques linear sweep voltammetry, potential step, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction were used for the characterization of the obtained electrode surfaces

Al-Pd alloy formation by aluminium underpotential deposition onto palladium from chloroaluminate melt

The possibility of electrochemical underpotential deposition of aluminium onto palladium from equimolar AlCl3+NaCl melts at temperatures between 200 ° and 300 °C was investigated. Electrochemical techniques used were cyclic voltammetry, chronoamperometry, potentiodynamic polarization and open circuit measurements. The results were analyzed by SEM, EDX and XRD. It was found that аluminium deposits underpotentially onto palladium at around 0.200 V vs. Al from the chloroaluminate melt used. It was established that under the given conditions, Al underpotential deposition onto the palladium substrate can result in AlPd and Al3Pd4 alloy synthesis by solid-state interdiffusion. The surface alloys synthetized are well adhering, microcrystalline deposits, having highly developed surface area suitable for applications such as hydrogen purification filters

Electrochemical Deposition of Aluminium on Aluminium from Ureabased Electrolyte

Electrochemical deposition/dissolution of aluminium to/from aluminium in deep eutectic solvent (DES), made of the AlCl3+urea, at temperatures of 25 to 60°C have been investigated. The depositions were performed in potentiostatic modes. The morphology of the obtained deposits was characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Critical overpotential of aluminium deposition increased from around – 0.120 V at 25°C to around – 0.050 V at 50°C. All recorded currents were generally speaking small, but would substantially increase with increasing working temperature (from 0.01 mA cm-2 up to 0.25 mA cm-2). Current/time transients recorded at overpotentials over – 0.100 V vs. Al indicate continuous three-dimensional nucleation and growth. Epitaxial growth over aluminium substrate was not observed under applied experimental conditions. Electrodeposition/dissolution processes of aluminium under chosen conditions were reversible, reproducible and slow (relatively small current densities, bellow 0.3 mA cm-2). Polarization curves recorded noticeable dependence of aluminium deposition/dissolution reversible potential on temperature applied. The deposits obtained showed variety of morphological shapes (needles, rods, flakes, Fig.1) depending on the working temperature and potential applied. All the deposits were made of crystallites grouped randomly into more or less separate agglomerates which were positioned over lower layer of densely populated much smaller crystallites. Lower layer showed good adherence to the substrate and exhibited high surface area. Density of the crystallites distribution over the substrate and complicity of the crystal forms increased with the potentials applied

Magnesium-Gold Alloy Formation by Underpotential Deposition of Magnesium onto Gold from Nitrate Melts

Magnesium underpotential deposition on gold electrodes from magnesium nitrate-ammonium nitrate melts has been investigated. Linear sweep voltammetry and potential step were used as electrochemical techniques. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) were used for characterization of obtained electrode surfaces. It was observed that reduction processes of nitrate, nitrite and traces of water (when present), in the Mg underpotential range studied, proceeded simultaneously with magnesium underpotential deposition. There was no clear evidence of Mg/Au alloy formation induced by Mg UPD from the melt made from eutectic mixture [Mg(NO3)(2).6H(2)O + NH4NO3.XH2O]. However, EDS and XRD analysis showed magnesium present in the gold substrate and four different Mg/Au alloys being formed as a result of magnesium underpotential deposition and interdiffusion between Mg deposit and Au substrate from the melt made of a nonaqueous [Mg(NO3)(2) + NH4NO3] eutectic mixture at 460 K

Formation and characterization of alloys obtained through underpotential deposition of aluminum onto zirconium, palladium and vanadium from aluminum (III) chloride and sodium chloride equimolar melts.

Ovaj rad je imao za cilj da ustanovi mogućnost elektrotaloženja aluminijuma pri potpotencijalima (underpotential deposition - UPD) na cirkonijumu, paladijumu i vanadijumu iz ekvimolarnih rastopa bezvodnog aluminijum(III)-hlorida i natrijum-hlorida na temperaturama znatno nižim od onih neophodnih za uobičajenu metalurgiju aluminijuma. U slučaju da dolazi do taloženja aluminijuma, elektrohemijskim metodama i metodama karakterizacije materijala utvrdila bi se pojava eventualno formiranih legura. Preliminarna procena izvedena na osnovu trenutne literature je ustanovila da bi se taloženje aluminijuma pri potpotencijalima trebalo odvijati na podlozi od paladijuma, verovatno na podlozi od vanadijuma i najverovatnije ne na podlozi od cirkonijuma. Paladijum, vanadijum i cirkonijum, kao radne elektrode, ispitivane su u okviru sistema koji je sadržao ekvimolarni rastop bezvodnog aluminijum(III)-hlorida i natrijum-hlorida, na temperaturama od 200°C, 250°C i 300°C u inertnoj atmosferi argona. Elektrohemijske studije površina paladijuma, vanadijuma i cirkonijuma pokazale su da dolazi do taloženje aluminijuma pri potpotencijalima. Dalja analiza cikličkih voltamograma, krivih „otvorenog kola“ i polarizacije su pokazale pojavu formiranja površinskih legura. Ovi nalazi su potvrđeni EDX, EDS, XRD i AFM rezultatima. Na osnovu dobijenih rezultata, dostupnih faznih dijagrama i dostupne literature, sledeće površinske faze su identifikovane kao formirane legure: - AlPd, Al3Pd2 i Al3Pd4 za podlogu od Pd, - Al23V4, Al8V5 i AlV3 za podlogu od V, - AlZr, AlZr2, Al2Zr, Al3Zr5, Al3Zr2 i Al3Zr za podlogu od Zr. Prikazani su parametri procesa za industrijsku primenu. Iako nije optimalan za masovnu proizvodnju, dati proces bi se mogao konzistentno primeniti u slučajevima gde bi cilj bio razvijanje površinskih legura na prethodno termalno ili mehanički formiranim komponentama.This work looked to estabilish the possibility of underpotential deposition (UPD) of aluminum onto palladium, vanadium and zirconium samples from equimolar melts of anhydrous aluminum chloride and sodium chloride at temperature that are significantly less than those of conventional alluminum metallurgy. Also, if any deposits were to be generated, confirmation was to be conducted if any alloy formation was to take place by use of electrochemical and material characterization techniques. Preliminary assessment based on the current literature on the topic concluded that UPD deposition should occur on palladium potentially would occur on vanadium and mostly would not occur on the zirconium substrates. Palladium, vanadium and zirconium substrates as working electrodes were evaluated within systems containing melts consisting of anhydrous aluminum chloride and sodium chloride, at temperatures of 200°C, 250°C and 300°C in inert argon atmosphere. Palladium, vanadium and zirconium substrate electrochemical studies showed aluminium UPD took place. Further evaluation of cyclic voltammograms, “open circuit” and polarization curves showed that surface alloy formation occurred as well. These findings were confirmed by EDX, EDS, XRD and AFM characterization results. Based on these results and current phase diagrams and other contemporary literature, following phases were identified as resulting alloys: - AlPd, Al3Pd2 and Al3Pd4 for Pd substrate, - Al23V4, Al8V5 and AlV3 for V substrate, - AlZr, AlZr2, Al2Zr, Al3Zr5, Al3Zr2, and Al3Zr for Zr substrate. General parameters for potential proces industrialization were considered. While not optimal for mass production, this proces can be applied consistently and repeatably for specialized, targeted applications of introducing surface alloys to already thermally or mechanically formed components

Formation and characterization of alloys obtained through underpotential deposition of aluminum onto zirconium, palladium and vanadium from aluminum (III) chloride and sodium chloride equimolar melts.

Ovaj rad je imao za cilj da ustanovi mogućnost elektrotaloženja aluminijuma pri potpotencijalima (underpotential deposition - UPD) na cirkonijumu, paladijumu i vanadijumu iz ekvimolarnih rastopa bezvodnog aluminijum(III)-hlorida i natrijum-hlorida na temperaturama znatno nižim od onih neophodnih za uobičajenu metalurgiju aluminijuma. U slučaju da dolazi do taloženja aluminijuma, elektrohemijskim metodama i metodama karakterizacije materijala utvrdila bi se pojava eventualno formiranih legura. Preliminarna procena izvedena na osnovu trenutne literature je ustanovila da bi se taloženje aluminijuma pri potpotencijalima trebalo odvijati na podlozi od paladijuma, verovatno na podlozi od vanadijuma i najverovatnije ne na podlozi od cirkonijuma. Paladijum, vanadijum i cirkonijum, kao radne elektrode, ispitivane su u okviru sistema koji je sadržao ekvimolarni rastop bezvodnog aluminijum(III)-hlorida i natrijum-hlorida, na temperaturama od 200°C, 250°C i 300°C u inertnoj atmosferi argona. Elektrohemijske studije površina paladijuma, vanadijuma i cirkonijuma pokazale su da dolazi do taloženje aluminijuma pri potpotencijalima. Dalja analiza cikličkih voltamograma, krivih „otvorenog kola“ i polarizacije su pokazale pojavu formiranja površinskih legura. Ovi nalazi su potvrđeni EDX, EDS, XRD i AFM rezultatima. Na osnovu dobijenih rezultata, dostupnih faznih dijagrama i dostupne literature, sledeće površinske faze su identifikovane kao formirane legure: - AlPd, Al3Pd2 i Al3Pd4 za podlogu od Pd, - Al23V4, Al8V5 i AlV3 za podlogu od V, - AlZr, AlZr2, Al2Zr, Al3Zr5, Al3Zr2 i Al3Zr za podlogu od Zr. Prikazani su parametri procesa za industrijsku primenu. Iako nije optimalan za masovnu proizvodnju, dati proces bi se mogao konzistentno primeniti u slučajevima gde bi cilj bio razvijanje površinskih legura na prethodno termalno ili mehanički formiranim komponentama.This work looked to estabilish the possibility of underpotential deposition (UPD) of aluminum onto palladium, vanadium and zirconium samples from equimolar melts of anhydrous aluminum chloride and sodium chloride at temperature that are significantly less than those of conventional alluminum metallurgy. Also, if any deposits were to be generated, confirmation was to be conducted if any alloy formation was to take place by use of electrochemical and material characterization techniques. Preliminary assessment based on the current literature on the topic concluded that UPD deposition should occur on palladium potentially would occur on vanadium and mostly would not occur on the zirconium substrates. Palladium, vanadium and zirconium substrates as working electrodes were evaluated within systems containing melts consisting of anhydrous aluminum chloride and sodium chloride, at temperatures of 200°C, 250°C and 300°C in inert argon atmosphere. Palladium, vanadium and zirconium substrate electrochemical studies showed aluminium UPD took place. Further evaluation of cyclic voltammograms, “open circuit” and polarization curves showed that surface alloy formation occurred as well. These findings were confirmed by EDX, EDS, XRD and AFM characterization results. Based on these results and current phase diagrams and other contemporary literature, following phases were identified as resulting alloys: - AlPd, Al3Pd2 and Al3Pd4 for Pd substrate, - Al23V4, Al8V5 and AlV3 for V substrate, - AlZr, AlZr2, Al2Zr, Al3Zr5, Al3Zr2, and Al3Zr for Zr substrate. General parameters for potential proces industrialization were considered. While not optimal for mass production, this proces can be applied consistently and repeatably for specialized, targeted applications of introducing surface alloys to already thermally or mechanically formed components

Al-Pd alloy formation by aluminium underpotential deposition onto palladium from chloroaluminate melt

Aluminium was underpotentially deposited onto palladium substrate from the equimolar AlCl3+NaCl melt at 250º and 300 ºC. Electrochemical methods used were linear sweep voltammetry and potential step. The obtained samples were analysed by scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy and X-ray diffraction. The aluminium underpotential deposition is followed by interdiffusion of very thin Al deposit and Pd substrate which lead to the formation of surface Al-Pd intermetallic compounds. The constant-potential regions measured during the low-current stripping method corresponded to the coexistence of three pairs of the metallicintermetallic phases. This indicated that formation of Al-Pd alloys in a very controlled way and under technologically suitable conditions can be done at temperatures equal to and below 250ºC

Aluminium electrodeposition under novel conditions from AlCl3–urea deep eutectic solvent at room temperature

The electrodeposition of aluminium on glassy carbon and aluminium substrates from AlCl3–urea deep eutectic solvent (DES) system at near room temperatures was investigated, without additional purification of the chemicals used to prepare the electrolyte and without rigorous control of moisture and oxygen present in the working space. The effects of changing temperature, working potential, controlled deposition current density and deposition time on the morphology of deposited aluminium without stirring of the electrolyte were recorded. Using potentiostatic and galvanostatic techniques, aluminium was electrodeposited from the deep eutectic solvent (n(AlCl3):n(urea)=1.6:1) onto glassy carbon and aluminium substrates at temperatures ranging from 25 to 50 °C. Using SEM, EDS and XRD techniques, substrates were studied and confirmed the presence of aluminium deposits following both potentiostatic and galvanostatic regimes. The shape and size of Al grains deposited depended on the time of deposition and varied in size from nanometers to micrometers and in shape from regular crystal forms to needle-like and flake-like structures

Aluminium underpotential deposition onto zirconium

Attempts were made to electrodeposit aluminium at aluminium underpotential-UPD from a low temperature equimolar ch/oroa/uminate melt (200 °C, 250 °C and 300 °C) onto zirconium. Experimental techniques used were linear sweep voltammetry, potential step and analytical techniques were scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Contrary to the widely accepted hypothesis aluminium UPD on zirconium was observed. It was shown that aluminium UPD facilitates alloy formation between the deposited aluminium monolayer and the zirconium substrate by interdiffusion. XRD analysis revealed a number of aluminium/zirconium alloys formed at the temperatures substantially lower than those needed for thermal preparation of those same alloys