Inhibition of chloride pitting corrosion of mild steel by sodium gluconate

The effect of gluconate (G) anion on the inhibition of chloride pitting cor rosion of Delta vanadium steel has been studied using potentiodynamic and s canning electron microscopy (SEM) techniques. The effect of concentration o f G ions, pH, potential scanning rate and composition of mild steel are dis cussed. The data show that complete protection of mild steel from pitting c orrosion is achieved with a very low concentration of G ions in weak alkali ne media. Fitting corrosion increases with increasing sodium gluconate (SG) concentrations due to a formation of soluble Fe-G complex. The critical pi tting potential depends on the chloride and G ion concentrations, pH, scan rate and the composition of the steel. An increase of Mn% in the compositio n of the steel leads to the increase of the pitting corrosion potential tow ards the positive direction, i.e., increases the resistance to pitting corr osion. The presence of vanadium in the steel also increases its resistance to pitting corrosion. (C) 2000 Elsevier Science B.V. All rights reserved.