PRETREATMENT OF ALUMINUM SURFACES WITH COMPOUNDS CONTAINING ZIRCONIUM AND MOLYBDENUM Russian patent published in 2021 - IPC C23C22/44 C23C22/73 C23C22/80 

FIELD: chemistry; etching.

SUBSTANCE: group of inventions relates to the pretreatment of workpieces having a surface of aluminum or aluminum alloys for forming without cutting and/or joining by welding or adhesive connection with pretreated or optionally precoated workpieces or with optionally pretreated parts consisting of steel and/or galvanized and/or galvanized alloy steel. The workpieces are etched, washed with water and brought into contact with an aqueous acidic chromium-free solution containing Zr in the form of complex fluoride and Mo in the form of molybdate, in a mass ratio of Zr:Mo, calculated as metallic Zr/Mo, ranging from 15:1 to 3.5:1 or from 2:1 to 1:2. In this case, the workpieces are treated in such a way that after subsequent drying, in each case, the mass of the Zr and Mo layer is obtained, which is from 2 to 15 mg/m². A solution is used containing 100 to 800 mg/l Zr and 30 to 100 mg/l Mo calculated as metallic Zr/Mo and having a pH of 2.5 to 4.5, or a solution containing 0.4 to 7.5 g/l Zr and 0.4 to 7.5 g/l Mo calculated as metallic Zr/Mo and having a pH of 1.0 to 3.0.

EFFECT: obtaining workpieces that have corrosion protection, good phosphatibility and adhesion, as well as a low volumetric resistivity, which is almost the same on all parts of the workpiece surface.

15 cl, 4 tbl