Abstract: The invention concerns a method of pretreating aluminum or aluminum alloy surfaces before application of a permanent corrosion-protective conversion coating treatment, in particular before phosphating in acidic phosphating baths containing zinc, a chromating treatment, or a chromate free treatment. The method is characterized in that the surfaces are brought into contact with acidic aqueous treatment solutions containing complex fluorides of the elements boron, silicon, titanium, zirconium, or hafnium, alone or in mixtures with each other, at total concentrations between 100 and 4000 mg/L and at a pH between 0.3 and 3.5. Following the pretreatment, the aluminum or aluminum alloy parts may, after shaping if necessary, be joined by adhesive bonding and/or welding to each other or to parts made of steel, zinc plated and/or zinc alloy plated steel, and/or aluminum or aluminum alloy plated steel.

Abstract: Liquid phosphate-free single phase degreasing compositions for aluminum surfaces containing one or more builders, sequestrants and surfactants in aqueous alkaline solution, particularly containing alkali metal and/or ammonium carbonate, alkali metal and/or ammonium hydrogen carbonate, one or more acrylic polymers, optionally one or more other complexing agents which complement or partly replace the acrylic polymers, one or more anionic or nonionic surfactants, optionally other active substances and/or auxiliaries of the type normally used in degreasing compositions and water.

Abstract: A process for sealing anodically produced oxide layers on aluminum and aluminum alloys by treating them with an aqueous solution at a temperature between about 90.degree. C. and its boiling point, wherein the aqueous solution has a pH of from about 4 to about 8 and and contains from about 0.0005 to about 0.5 g/l of at least one phosphinocarboxylic acid or its water-soluble salt.