Inhibition of chloride pitting corrosion of mild steel by sodium gluconate

Abstract The effect of gluconate (G) anion on the inhibition of chloride pitting corrosion of Delta vanadium steel has been studied using potentiodynamic and scanning electron microscopy (SEM) techniques. The effect of concentration of G ions, pH, potential scanning rate and composition of mild steel are discussed. The data show that complete protection of mild steel from pitting corrosion is achieved with a very low concentration of G ions in weak alkaline media. Pitting corrosion increases with increasing sodium gluconate (SG) concentrations due to a formation of soluble Fe–G complex. The critical pitting potential depends on the chloride and G ion concentrations, pH, scan rate and the composition of the steel. An increase of Mn% in the composition of the steel leads to the increase of the pitting corrosion potential towards the positive direction, i.e., increases the resistance to pitting corrosion. The presence of vanadium in the steel also increases its resistance to pitting corrosion.