Evaluation of Corrosion Inhibiting Pigments for Aluminum

Laboratory corrosion tests of inhibitors indicate that the inhibitors which contain hexavalent chromium gave the best protection for aluminum. However, potassium permanganate, also an oxidizing agent which deposits manganese dioxide on the aluminum, prevents corrosion. For screening inhibitors, a weighed aluminum coupon was immersed in a 5 sodium chloride solution containing 0.1 of inhibitor. The coupon was left undisturbed for approximately three weeks. It was then rinsed in distilled water, dried, and weighed and examined visually.