MoO42- as a soluble inhibitor for Zn in neutral and alkaline solutions.

International audienceThe inhibitive action of soluble Na2MoO4 on the spontaneous reactivity of hot dip galvanized steel in 0.5 M NaCl was studied at pH 4–13 by a direct measurement of Zn dissolution rate in the flowing electrolyte and postmortem surface analysis. The stability and the composition of Mo-rich films depended on the solution pH and flow conditions. The inhibition efficiency of soluble Mo(VI) correlated with the composition of the films: Mo(V)-rich films were immediately formed under uniform flow at pH 6–12, and the inhibition efficiency of Mo(VI) in these conditions (>92%) was comparable with the efficiency of Cr(VI)