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.

Abstract

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