| 摘要 |
The invention concerns a method of pretreating aluminum or aluminum all oy 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 solution s 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 plate d steel, and/or aluminum or aluminum alloy plated steel.
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