Effect of pH on sacrificial anode aluminum alloy in acidic chloride solution

Abstract

In this study, the effect of pH on sacrificial anode effect of aluminum alloy in acidic chloride solutions containing copper ion was investigated by using immersion corrosion tests and electrical polarization measurements. The corrosion tests were performed for A3003 alone and A3003 coupled with A7072 simulated clad material. A3003 was sacrificially protected by A7072 under the solution of over pH3 at 200 ppmCl^‒. In contrast, in the case of a solution below pH2, the corrosion weight loss of A3003 coupled with A7072 did not decrease compared to that of A3003 alone. Additionally, A3003 coupled with A7072 actively dissolved similar to A3003 alone. These are because the corrosion potential of A3003 did not become less noble when coupled with A7072 due to nobler pitting potential of A7072.