Kinetic of corrosion reactions in acid and neutral solutions on electrochemically deposited Ni-W alloys

Abstract

Ni-W alloys were electrochemically deposited from an ammonia-citrate electrolyte on rotating disc electrode with a gold disc, by direct and pulsating current. The corrosion potential and kinetics of cathodic and anodic reaction were investigated on the alloys with molar fraction of tungsten from 0.11 to 0.25 in acid and neutral sulfate solutions of various pH. On the basis of kinetic equations resulting from these data, it was proposed that a barrier lazer of nickel and tungsten oxide was formed on the alloy surface preventing further alloy dissolution.

Prevlake legure Ni-W su elektrohemijski taložene iz amonijačno-citratnog elektrolita, na rotirajuću disk elektrodu od zlata, konstantnom i pulsirajućom strujom. Korozioni potencijal, kinetika katodne i anodne reakcije na elektrohemijski taloženim prevlakama legura Ni-W, sa udelom volframa od 0,11 do 0,25, su ispitivani u kiselim i neutralnim sulfatnim rastvorima, različitih pH vrednosti. Na osnovu dobijenih rezultata izvedene su kinetičke jednačine za katodnu i anodnu reakciju, koje ukazuju na formiranje barijernog sloja oksida volframa i nikla koji sprečava rastvaranje legure i delimično se redukuje pri katodnoj polarizaciji.