PROCESS OF AFTERTREATING CONVERSION LAYERS

摘要

The invention teaches that conversion layers formed an surfaces of aluminum or aluminum alloys by a treatment with solutions based on titanium, zirconium and/or hafnium ions should be aftertreated with aqueous solutions which contain aluminum, zirconium and fluoride and have been adjusted to a pH value ? 5. In the solutions used for aftertreating the total concentration of Al + Zr + F preferably lies between 0.1 and 8.0 g/l, preferably between 0.2 and 5.0 g/l, and the Al : Zr : F mole ratios have been adjusted to (0.15 to 8.0) : 1 : (5 to 52), particularly to (0.15 to 2.0) : 1 : (5 to 16) and most desirably to (0.15 to 0.67) : 1 : (5 to 7). The aftertreating solutions should be at a temperature of 20 to 80.degree.C, preferably of 20 to 50.degree.C, and are preferably applied for 1 to 30 seconds. The process in accordance with the invention is particularly used to pretreat the surfaces before a succeeding painting, film laminating or adhesive coating operation.