Acidic cleaning aqueous solution for aluminum and aluminum alloy and process for cleaning the same

Abstract

Disclosed is an acidic cleaning aqueous solution for aluminum and aluminum alloy and a process for cleaning the same, intended to execute acidic cleaning without using harmful fluoride and chloride ions. The oxidation-reduction potential of a cleaning bath is controlled to be at 0.5 to 0.8 V (vs. Ag-AgCl). The cleaning bath is obtained by diluting an acidic cleaning aqueous solution for aluminum and aluminum alloy to a predetermined volume. The acidic cleaning aqueous solution contains specified amounts of at least one of inorganic acids, Br.sup.- ions and oxidized metal ions, with the addition of a surfactant and oxidizing agent if necessary. It is thus possible to present a uniform etching effect irrespective of low temperature (below 60.degree. C.) without containing fluoride ions and chromic ions within the acidic cleaning aqueous solution. Br.sup.- also has an effect of inhibiting the oxidation-decomposition reaction of the surfactant arising from the oxidizing agent and oxidized metal ions, thereby obtaining a long-life acidic cleaning aqueous solution.

Dependencies are inferred from the claim text.