Corrosion inhibition of 304 stainless steel in H 3 PO 4 –Cl − solutions by chromium,molybdenum,nitrogen,tungsten,and boron anions: Part 1: Polarisation measurements

Abstract

Corrosion inhibition studies of 304 stainless steel in phosphoric acid–chloride solutions with chromium, molybdenum, nitrogen, tungsten, and boron anions have been undertaken. The effect of dichromate, molybdate, tungstate, borate, nitrite, and nitrate ions on the behaviour of the alloy has been studied using potentiodynamic and potentiostatic polarisation techniques. The potentiodynamic results showed that most of these additives improve the corrosion resistance of the alloy. The additives retard both active and pitting attack to an extent depending on the type and concentration of the additive. The potentiostatic (i–t curve) results showed that only nitrite and nitrate salts could achieve complete inhibition of pitting corrosion. The results have been correlated with the beneficial action of the corresponding alloying elements.