<p>Cilj ovog rada bio je da se ustanovi da li dolazi do elektrohemijskog taloženja niobijuma i aluminijuma iz hloroaluminatnih rastopa obogaćenih niobijumom na podlogama od staklastog ugljenika, platine i zlata. Nadalje, ako dolazi do rečenog taloženja, da li pri tome dolazi i do formiranja legura niobijuma sa izabranim podlogama kao i da li dolazi do formiranja legura niobijuma sa zajednički taloženim aluminijumom. I na kraju, cilj je bio da se navedeni fenomeni ostvare na što nižim temperaturama.</p><p>Nb i Al su elektrohemijski taloženi na staklastom ugljeniku, platini i zlatu pri 200 °C, pod atmosferom argona, iz rastopa napravljenog od ekvimolarne smeše AlCl<sub>3</sub> + NaCl kome je dodat niobijum.</p><p>U istraživanjima su korišćene: linearna i ciklička voltametrija, metoda potenciodinamičke polarizacione krive, metoda „otvorenog kola“, hronoamperometrija, SEM, EDS, AFM i XRD analiza.</p><p>Elektrohemijsko taloženje Nb i Al iz primenjenih rastopa pri potpotencijalima uočeno je na podlozi od zlata. Taloženje niobijuma pri potpotencijalima na zlatu je novost, a taloženje Al na zlatu pri potpotencijalima poznato je od ranije. Elektrotaloženje Al i Nb iz primenjenih rastopa pri potpotencijalu na zlatu prethodi procesima elektrotaloženja niobijuma i aluminijuma pri natpotencijalima. Rezultat ovih procesa su Nb/Au i Al/Au legure nastale zajedničkim taloženjem i interdifuzijom istaloženog Nb, odnosno Al i podloge - zlata (AlAu, AlAu<sub>2</sub> , AlAu<sub>4</sub>, AlNb<sub>2</sub> , AlNb<sub>3</sub> , Au<sub>2</sub>Nb, Au<sub>2</sub>Nb<sub>3</sub> , AuNb<sub>3</sub> , AlNb<sub>3</sub>).</p><p>Elektrohemijsko taloženje Nb iz primenjenih rastopa pri potpotencijalima uočeno je na platini i prethodi procesima elektrotaloženja Nb i Al. Rezultat su formirane Nb/Pt legure nastale interdifuzijom istaloženog Nb i podloge - platine (Nb<sub>3</sub>Pt). Pri natpotencijalima aluminijuma na platini dolazi do taloženja metalnog niobijuma, metalnog aluminijuma i zajedničkog taloženja Nb i Al. Kao posledica ovih procesa dolazi i do formiranja legura (AlNb<sub>3</sub>, Al<sub>3</sub>Pt<sub>5</sub> , Nb<sub>3</sub>Pt).</p><p>Elektrohemijsko taloženje niobijuma iz primenjenih rastopa na izabranim podlogama odigrava se na potencijalima koji su pozitivniji od potencijala elektrotaloženja aluminijuma.</p><p>Sve dobijene legure formirane su pri temperaturi od 200 °C što je nekoliko stotina stepeni niže od odgovarajućih temperatura potrebnih da se formiraju termičkim putem. </p> / <p>The aim of this study was to establish electrodeposition of niobium and aluminium from chloroaluminate melt (AlCl<sub>3</sub> + NaCl) enriched with niobium onto gold, platinum and glassy carbon substrates. Furthermore, if such deposition is shown to occur, to assess if it can lead to formation ofniobium alloys with chosen substrates or formation of Nb/Al alloys as a result of codeposition. And finally, if the deposition is indeed confirmed, to establish the lowest operational temperature at which it is possible.</p><p>Niobium and aluminium were electrodeposited onto glassy carbon, gold and platinum at 200 °C, under an argon atmophere from the melt made of equimolar mixture AlCl<sub>3</sub> + NaCl with niobium being added.</p><p>Research methods used were: cyclic voltammetry, potentiodynamic polarization curves, "open circuit”, chronoamperometry, SEM, EDS, AFM and XRD analysis. Underpotential deposition of Nb and Al from the melt onto gold substrate was observed. Of the two, niobium deposition is a novelty, while alumininum deposition has been previously studied. Underpotential deposition of NB and Al onto gold from given melt precedes the overpotential deposition of aluminium and niobium onto gold. The result of these processes are Nb/Au and Al/Au alloys formed by codeposition of the two metals and interdiffusion between the Nb and Al deposits and the substrate -gold (AlAu, AlAu<sub>2</sub>, AlAu<sub>4</sub>, AlNb<sub>2</sub>, AlNb<sub>3</sub>, Au<sub>2</sub>Nb, Au<sub>2</sub>Nb<sub>3</sub>, AuNb<sub>3</sub>, AlNb<sub>3</sub>). Underpotential deposition of niobium onto platinum from used melts was recorded and it precedes the processes of overpotential deposition of niobium and aluminium. The result is formation of Nb/Pt alloys as a consequence of interdiffusion between the substrate and the deposited Nb (Nb<sub>3</sub>Pt). The potentials more negative than the aluminium deposition potential in the used system lead to deposition of niobium and aluminium individually and jointly. Thus, a number of alloys are formed (AlNb<sub>3</sub>, Al<sub>3</sub>Pt<sub>5</sub>, Nb<sub>3</sub>Pt). Niobium electrodeposition onto chosen substrates from the melt applied takes place at potentials which are more positive than the potential of electrodeposition of aluminium. Formation of the obtained alloys occurred at a temperature of 200 °C which is several hundred degrees lower than the temperatures needed for their formation by thermal methods.</p>
| Identifer | oai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)104330 |
| Date | 18 May 2017 |
| Creators | Vukićević Nataša |
| Contributors | Jovanović Ljiljana, Cvetković Vesna, Vaštag Đenđi, Stevanović Jasmina |
| Publisher | Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, University of Novi Sad, Faculty of Sciences at Novi Sad |
| Source Sets | University of Novi Sad |
| Language | Serbian |
| Detected Language | English |
| Type | PhD thesis |
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