INHIBITION EFFECT OF POTASSIUM-IODIDE ON CORROSION OF STAINLESS-STEEL IN HYDROCHLORIC-ACID SOLUTION

The inhibition effect of potassium iodide on the corrosion of stainless steel has been examined using weight loss and electrochemical measurements. Potassium iodide was found to be an excellent inhibitor for stainless steel types 316, 430 and 440 (efficiency more than 95%), and moderate for type 304. The corrosion rates in 1 M HCl and in presence of potassium iodide fit an Arrhenius equation. The presence of potassium iodide lowered both the activation energy and the rate of reaction. Polarization measurements indicated that potassium iodide acts as an anodic inhibitor particularly at higher concentrations and as a cathodic inhibitor at lower concentrations. The synergistic effect of potassium iodide on the inhibitive efficiency of the organic substances was studied.