EFFECT OF ELECTROLYTE VOLUME ON THE ACID DISSOLUTION OF ALUMINUM-ALLOY-7075

Dissolution of aluminum alloy 7075 (UNS A97075) was studied using weig ht-loss measurements in a series of hydrochloric acid (HCl) solutions varying in concentration from 0.5 M to 2 M. The open-circuit reaction was observed to be first order in the hydrogen ion. In acid solutions having a fixed supply of hydrogen ions, corrosion of Al 7075 was arres ted by depletion of that available supply. For a given initial acid mo larity (M) and a given initial surface area, the total amount of corro sion (weight loss [G]) is given by G = 0.0101 VM where V is the volume of solution. For a given set of conditions (initial acid concentratio n, initial surface area, and volume of solution), the time for cessati on of the corrosion reaction as calculated from first-order reaction k inetics was in agreement with experimentally determined values. Two co rrosion systems were discussed as possible applications involving cess ation of a corrosion, reaction in acid environments caused by depletio n of the hydrogen ion supply.