METHOD FOR COATING METAL SURFACES OF SUBSTRATES, AND OBJECTS COATED ACCORDING TO THIS METHOD

摘要

The invention relates to a method for coating surfaces, to a corresponding coating, and to the use of the objects coated according to said method. According to the invention, this is achieved by a method for coating metal surfaces of substrates, having the following steps or consisting of the following steps: I. providing a substrate with a cleaned metal surface, II. contacting and coating metal surfaces with an aqueous composition in the form of a dispersion and/or a suspension, III. optionally rinsing the organic coating, and IV. drying and/or baking the organic coating or V. optionally drying the organic coating and coating same with a similar or another coating composition prior to drying and/or baking. The invention is characterized in that the coating process in step II is carried out using an aqueous composition in the form of a dispersion and/or a suspension, said composition containing a complex fluoride selected from the group consisting of hexa- or tetrafluorides of the elements titanium, zirconium, hafnium, silicon, aluminum, and/or boron in a quantity of 1.110 - 6 mol/l to 0.30 mol/l based on the cations, wherein at least one anionic polyelectrolyte, in a quantity of 0.01 to 5.0 wt.% based on the total mass of the resulting mixture, is added to an anionically stabilized dispersion made of film-forming polymers and/or a suspension made of film-forming inorganic particles with a solids content of 2 to 40 wt.% and an average particle size of 10 to 1000 nm, said dispersion and/or suspension being stable in the pH value range of 0.5 to 7Ø The aqueous composition has a pH value ranging from 0.5 to 7.0 and forms a coating based on an ionogenic gel which binds cations released from the metal surface, said cations originating from a pretreatment stage and/or from the contacting process in step II.