Electrochemical impedance spectroscopy and cyclic voltammetry study of carbon-alloyed iron aluminides in sulfuric acid

The electrochemical behaviour of three carbon-alloyed iron aluminides Fe–11.0Al–0.5C, Fe–10.5Al–0.9C and Fe–10.5Al–0.8C–0.2Ce (in wt%) has been studied in 0.25 mol/l H2SO4 solution using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry techniques. A 0.05% C steel was used for comparison purposes. EIS studies were conducted after 1 h and 24 h of immersion in the acidic solution. The results obtained indicated improved surface film properties in the case Ce-alloyed iron aluminides as compared to the other two iron aluminides. This has been attributed to enhancement in surface passivity with Ce addition. Cyclic voltammetry experiments indicated that addition of Ce modified the electrochemical reactions on the surface.