Corrosion and sulphate ion reduction studies on Ni and Pt surfaces in with and without V2O5 in (Li,Na,K)2SO4 melt

Abstract In the present investigation corrosion and sulphate ion reduction on the nickel and platinum surfaces, respectively have been studied in (Li,Na,K) 2 SO 4 melt in the presence and absence of V 2 O 5 at 550 °C. The corrosion or oxidation rate of nickel was derived by Tafel extrapolation method while cyclic voltammetry measurement was employed for the determination of electrochemical behaviour of sulphate ion. According to result obtained, corrosion of nickel increases very fast after the addition of V 2 O 5 and becomes more than two orders of magnitude higher in the presence of 3% V 2 O 5 in the melt. Three well defined cathodic peaks related to vanadate ion reduction, were clearly observed in the cyclovoltammogram obtained on the Pt surfaces in presence of V 2 O 5 in the melt. Observation of three reduction peaks could be due to subsequent reduction of vanadate ion to its lower oxidation state. From the results, a conclusion has been drawn that a strong ability of vanadium to reduce in its lower oxidation state by consuming electrons released by sulphate ion oxidation, is mainly responsible for enhancement of corrosion or oxidation of the nickel in the sulphates melt.