The influence of silicate and sulphate anions on the anodic corrosion and the transpassivity of iron and silicon-rich steel in concentrated KOH solution
By Milan Cekerevac,Miloš Simicic, Ljiljana Nikolic Bujanovic, Negica Popovic
Published in Surface and Coatings Technology
2014
Abstract
The effect of sulphate and silicate addition in a 10 M KOH electrolyte on the anodic corrosion and transpassivity of iron and steel rich in silicon are explored by cyclic and linear sweep voltammetry. Formation of ferrate(VI) in the iron transpassivity region is noticed in all explored electrolytes. The electrochemical sulphato- and silico-ferrate(VI) formation is discussed as a possible result of Fe 3 III ( Si 1.32 Fe 0.68 ) O 5 (OH) 4 and [Fe(II)4Fe(III)2(OH)12]SO4 oxidation in the 10 M KOH electrolytes with silicate and sulphate, respectively. The presence of Fe3(Si1.32Fe0.68)O5(OH)4 in the anodic layer of silicon steel and the crystal structure of electrochemically synthesised Ba(Fe, S)O4 have been revealed by XRD.