INFLUENCE OF CATIONS ON THE CORROSION BEHAVIOUR OF ALUMINIUM ALLOYS IN DRINKING WATER AND MODEL TAP WATER

摘要

The corrosion behaviour of aluminium alloys in small amounts of chloride ions containing solutions was examined by focusing on the effect of added cations and solution pH (buffer reaction of added 0.5 kmol/m~3 H_3BO_3/0.05 kmol/m~3 Na_2B_4O_7). The effect of Cu deposition on corrosion behaviour of aluminium alloys was also investigated. The 3003 aluminium alloy shows lower corrosion resistance than 5005 aluminium alloy in the tap water and model tap waters. Corrosion of aluminium alloys is accelerated by addition of Ca~(2+) ions to the model tap waters especially at low pH. This behaviour may be explained by H~+ concentration increases caused by CaCO_3 formation. Without Cl~- ions, Cu~(2+) ions do not increase the corrosion rate of the aluminium alloys.