A body, particularly a thin layer, of aluminium or aluminium alloy is given a corrosion-resistant bright dense barrier-type protective layer. The layer has a thickness in the range 50 to 500 nm and comprises aluminium oxide and a chelate complex of aluminium and at least one organic chelating compound....http://www.google.co.uk/patents/US5055356?utm_source=gb-gplus-sharePatent US5055356 - Aluminium and aluminium alloy having corrosion-resistant protective layer, and methods of making such a layer
