EFFECT OF CONCENTRATION AND ACIDITY OF SULFATE-SOLUTION ON ANODIC PASSIVATION OF IRON-CHROMIUM ALLOYS

It is shown that in sulfate solutions containing from 10(-2) to 1 N su lfate and having pH from 3 to 0, the passivation potentials E-p of iro n-chromium alloys with low (6%) chromium content, as distinct from E-p of alloys containing 17 and 28% Cr, decrease with an increase in not only pH, but also in the sulfate ion concentration. The effectiveness of the passivating action of sulfate on low-chromium steel, in turn, d epends' on the acidity of the medium. The results are interpreted in t erms of a possible effect of the active dissolution of the alloy on it s passivation potentials. For this purpose, the active dissolution rat es of alloys studied were determined in all of the solutions.