INFLUENCE OF CL- ON THE PASSIVITY OF FE AND NI IN ACID ORGANIC-SOLVENTS

The influence of HCl on the anodic behaviour of Fe and Ni in DMSO/1 M H2SO4 depends on the water content of the solution. In completely anhydrous solutions the current density at the same voltage is in no case enlarged and pittings are certainly not observed. At water contents in the range 2-50% the two metals show pitting corrosion, but the current density at the same voltage is much lower than in aqueous solutions. The true anodic polarization measured with an interrupting potentiostat is very high and probably caused by a salt layer. It may be the source of the inhibition effect of DMSO. Fe in DMF/1 M H2SO4 has a similar anodic behaviour depending on the HCl concentration, but the polarization in this anhydrous solvent is much lower. The inhibition effect also seems to be lower. © 1979 Chapman and Hall Ltd.