A metal article comprises two metals, and a first hole and an oxide layer are set correspondingly on the surfaces of the two metals. To avoid the electrolytic corrosion on the interface between the two metals during the formation of the first hole, the disclosure provides a method of manufacturing the metal article. By putting a metal substrate in a first electrolyte including an etching agent and a passivating agent and applying electricity on the metal substrate, the metal article with the first hole is formed without electrolytic corrosion. The disclosure also provides a metal composite, which is formed by setting a material part in the first hole of the metal article.

The present invention relates to an acidic aqueous composition for coating metallic surfaces, particularly of aluminium materials, that comprises, besides water and optionally further components, a) at least one compound selected from the group consisting of organoalkoxysilanes, organosilanols, polyorganosilanols, organosiloxanes and polyorganosiloxanes, b) at least one compound selected from the group consisting of titanium, zirconium, hafnium and aluminium compounds and silicon complex fluoride, and c) at least one copolymer which is stable at least in a segment of the pH range below 6 and which comprises, in alternating configuration, monomer units containing at least one carboxylic and/or phosphonic acid group and monomer units containing no acid group. The invention further relates to a corresponding coating method and to the use of the substrates coated by this method.

The present invention relates to an acidic aqueous composition for coating metallic surfaces, particularly of aluminium materials, that comprises, besides water and optionally further components, a) at least one compound selected from the group consisting of organoalkoxysilanes, organosilanols, polyorganosilanols, organosiloxanes and polyorganosiloxanes, b) at least one compound selected from the group consisting of titanium, zirconium, hafnium and aluminium compounds and silicon complex fluoride, and c) at least one copolymer which is stable at least in a segment of the pH range below 6 and which comprises, in alternating configuration, monomer units containing at least one carboxylic and/or phosphonic acid group and monomer units containing no acid group. The invention further relates to a corresponding coating method and to the use of the substrates coated by this method.

The invention relates to a method for operating a treatment system, by means of which an optimized workpiece treatment is facilitated. The method for operating a treatment system comprises the following steps: guiding workpieces through a treatment basin filled with a treatment medium in order to treat the workpieces; rinsing the workpieces with a rinsing medium while and/or after the workpieces are removed from the treatment basin; and producing the rinsing medium from the treatment medium, wherein the rinsing medium is produced using a preparation device preferably by filtering, in particular nano-filtering, the treatment medium.

The invention relates to a method for operating a treatment system, by means of which an optimized workpiece treatment is facilitated. The method for operating a treatment system comprises the following steps: guiding workpieces through a treatment basin filled with a treatment medium in order to treat the workpieces; rinsing the workpieces with a rinsing medium while and/or after the workpieces are removed from the treatment basin; and producing the rinsing medium from the treatment medium, wherein the rinsing medium is produced using a preparation device preferably by filtering, in particular nano-filtering, the treatment medium.

An aqueous solution for metal surface treatment includes an alkyl silicate or an oligomer thereof in a concentration of 0.005 mass % or more and less than 1 mass %, and an organic silane compound in a concentration of 0.005 mass % or more and less than 1 mass %. The aqueous solution has a pH of 2 or more and 7 or less.

The invention relates to a method for producing a silane-modified silicate. In order to obtain optimal corrosion protection properties, a silane compound according to the invention is at least partially hydrolyzed and/or condensed in the presence of a silicate compound at a pH value greater than or equal to 8 and then a pH value less than or equal to 7 is set by adding acid. The invention further relates to an aqueous acidic passivation composition for metal substrate coated with the passivation composition.

The invention relates to a method for producing a silane-modified silicate. In order to obtain optimal corrosion protection properties, a silane compound according to the invention is at least partially hydrolyzed and/or condensed in the presence of a silicate compound at a pH value greater than or equal to 8 and then a pH value less than or equal to 7 is set by adding acid. The invention further relates to an aqueous acidic passivation composition for metal substrate coated with the passivation composition.

The present invention relates to a method for the corrosion-protective and cleaning pretreatment of metallic components, produced at least partially from metallic materials from the elements iron, zinc and/or aluminum, with the use of an acid aqueous composition containing, in addition to the water-soluble compounds of the elements Zr and/or Ti causing the conversion of the metal surface, a mixture of an aliphatic diol and an aliphatic saturated polyhydroxy compound. It also comprises a chrome(VI)-free aqueous composition based on the constituents mentioned above which delivers outstanding results in cleaning and simultaneous corrosion-protective conversion of technical metal surfaces in one method step.

A method for post-treatment of a chromium finish surface to improve corrosion resistance comprising a) providing a substrate having a chromium finish surface, and at least one intermediate layer between the chromium finish surface and the substrate, selected from the group consisting of nickel, nickel alloys, copper and copper alloys, wherein the chromium finish surface is a surface of a trivalent chromium plated layer, obtained by electroplating the substrate, having the at least one intermediate layer, in a plating bath, the plating bath comprising chromium (III) ions; b) contacting the chromium finish surface with an aqueous solution, comprising a permanganate, at least one compound which is selected from a phosphorus-oxygen compound, a hydroxide, a nitrate, a borate, boric acid, a silicate, or a mixture of two or more of these compounds; c) forming a transparent corrosion protection layer onto the chromium finish surface during step b.