Desmutting of aluminium alloy 2024-T3 using rare earth electrolyte

The desmutting of 2024-T3 aluminium alloy using a new rare earth desmutting solution has been studied by SEM and X-ray photoelectron spectroscopy (XPS ). It was evident from SEM that, during desmutting, there was dissolution a nd etching of both the intermetallics and the basic oxide scale left after alkaline cleaning. In addition, copper from the intermetallics was deposite d as a residue on the surface of the desmutted alloy. The residue, in the f orm of precipitates similar to 200 nm in size, proved to be copper with an oxide coating. The addition of oxidants such as hydrogen peroxide (H2O2) an d potassium persulphate (K2S2O8) removed these precipitates. It was apparen t from XPS that the surface was coated with a thin 6 nm aluminium oxide aft er desmutting. MST/4287.