AC-electrochemical cleaning of aluminium

The effect of AC-electrochemical cleaning on rolled AA1050 and AA5182 is in vestigated in sulphuric and phosphoric acid under constant AC-current condi tions. Potential response and oxide thickness measurements demonstrate the difference between AC-cleaning and AC-anodising. The roles of the anodic an d cathodic charge cycles in creating the cleaned surface features are studi ed. For;AA1050 no contribution of the the cathodic hydrogen evolution react ion is witnessed. while for AA5182 an extra metal loss due to the reduction process is apparent. The cleaned surface is covered with a thin oxide laye r (<20 nm). Scanning electron micrographs show a rough and cratered surface after AC-cleaning rn phosphoric acid. The surface roughening is less sever e in sulphuric acid. No etchfilm formation is observed; the oxidised alumin ium is removed from the substrate into the solution. The AC-cleaning is mor e efficient in terms of metal loss (10 to 100 times faster in respectively sulphuric and phosphoric acid) than the traditional acid etching.