The induced deposition of W in the presence of iron-group metals has been known for a long time without a proper understanding of the mechanism of codeposition. Hints were made by several authors, concerning primarily a similar case of codeposition of Mo, which were not sufficiently substantiated by proper kinetic investigation as the research was oriented mainly toward practical aims. In the present investigation induced deposition of W with Ni was studied primarily from the point of view of the composition and phase structure of the resulting Ni-W alloy. The method of anodic linear sweep voltammetry was used to analyze deposits obtained at a rotating disc electrode, as it was proven to be a good tool for analysis of thin-layered deposits.
The polarisation diagram was found to exhibit a sharp current maximum and a subsequent decay at potentials at which Ni deposition starts. As some W oxide is found to deposit at less negative potential the sharp rise of current and the maximum are ascribed to catalytic effect of the oxide for hydrogen evolution, larger than that of depositing Ni-W alloy.
The deposit was found to exhibit two peaks upon anodic dissolution, both at significantly more positive potentials than that of Ni dissolution. The first peak is of limited quantity of electricity independent of the amount of the deposit, the increase of the latter being reflected in the second peak only.
An aging effect was found rendering an alloy requiring much more positive potentials for dissolution than those for dissolution of freshly deposited alloys.Taloženje volframa u prisustvu metala grupe gvožđa, indukovano taloženje, je fenomemen koji je odavno poznat. Međutim, mehanizam kodepozicije nije razjašnjen. Dosadašnja istraživanja indukovanog taloženja ( i to najčešće molibdena ) prvenstveno su bila usmerena ka primeni u praksi, a nedovoljno praćena odgovarajućim kinetičkim ispitivanjima. U ovom radu ispitivano je indukovano taloženje W sa Ni prvenstveno sa stanovišta sastava i fazne strukture dobijenih Ni-W legura. Metoda anodne linearne promene potencijala (ALSV) upotrebljena je za analizu prevlaka dobijenih na rotirajućoj disk elektrodi.
Na katodnim polarizacionim dijagramima taloženja nađen je oštar strujni maksimum na potencijalu koji odgovara početku taloženja Ni. Pad struje se može pripisati sporijem izdvajanju vodonika na leguri Ni-W, nego na oksidu volframa koji je se dobija pri manje negativnim potencijalima.
Na anodnim voltamogamima rastvaranja javljaju se dva karakteristična strujna vrha, oba na potencijalima znatno pozitivnijim od onih koji odgovaraju rastvaranju čistog Ni. Količina naelektrisanja koja odgovara prvom strujnom vrhu je ograničena odnosno, povećanje količine naelektrisanja pri taloženju odražava se u odgovarajućem porastu naelektrisanja drugog anodnog strujnog vrha.
Nađeno je da se legure, koje su stajale na sobnoj temperaturi u toku nekoliko časova posle taloženja, rastvaraju na znatno pozitivnijim potencijalim od onih koje su ispitivane neposredno posle taloženja, što ukazuje na stabilizaciju procesom u čvrsoj fazi
