Inhibition of Corrosion of Commercial Aluminum In Alkaline Solutions

Abstract

The corrosion rates for commercial aluminum, containing 4 percent manganese and 3 percent iron, have been determined in sodium hydroxide solutions under different conditions. The inhibitor efficiencies have been calculated for the following substances, the efficiency decreasing from 90 to 60 percent in the order: agar-agar, gum-acaciae, dextrin, gelatin, glue. Corrosion potentials have been measured with and without dextrin inhibitor, and cathodic and anodic polarization studies made. The results show that the dissolution of the metal is electrochemical in character. The corrosion process appears to be under mixed control with predominance of action of dextrin inhibitor on the anodic areas of the metal surface. 6.4.2, 4.3.3, 5.8.2