# US 8,771,800 B2 · Method for the local application of chemical conversion layers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,800 B2 - Document ID: US8771800B2 - Status: Granted - Kind: B2 - Application number: 12/849,334 - Filed: 2010-08-03 - Published: 2011-02-10 - Granted: 2014-07-08 - Earliest claimed: 2009-08-04 - Assignees: Airbus Operations GmbH - Applicants: Martin Beneke; Sonja Nixon; Franz Gammel - Inventors: Martin Beneke; Sonja Nixon; Franz Gammel - Web page: https://patentgrep.com/patent/US8771800B2 ## CPC - C23C 22/73: characterised by the process - C23C 22/34: containing fluorides or complex fluorides - C23C 2222/10: Use of solutions containing trivalent chromium but free of hexavalent chromium - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) ## Abstract The present invention relates to a method for producing a chemical conversion layer on a metal surface, comprising the following method steps: (i) providing at least one cloth having a defined area, which is resistant at least in the pH range from 2 to 7 and is tear-proof in the wet state, (ii) bringing the cloth into contact with a liquid, which contains at least one active component for the formation of the chemical conversion layer, so that the cloth is impregnated with the liquid, (iii), applying the cloth impregnated with the liquid to a metal surface, and (iv) removing the cloth from the metal surface at a moment at which the cloth is still at least damp. ## Claims ### Claim 1 A method for producing a chemical conversion layer on a metal surface, comprising: (i) providing at least one cloth having a defined surface, said cloth being resistant at least in the pH range of 2 to 7 and being tear-proof in the wet state, wherein the cloth is manufactured from fibers selected from the group consisting of cellulose, polyester, nylon, polypropylene, polyamide, polyvinyl alcohol, polyurethane fibers, and mixtures thereof, wherein a size of the at least one cloth is generally equal to the size of the metal surface to be treated; (ii) bringing the cloth into contact with a liquid containing at least one active component for the formation of the chemical conversion layer, so that the cloth is impregnated with the liquid, (iii) applying the cloth impregnated with the liquid to a metal surface, wherein the cloth is laid on the metal surface and is left stationary thereon; and (iv) removing the damp cloth from the metal surface, wherein the cloth is removed in step (iv) at earliest after 2 minutes after the application to the metal surface in step (iii). ### Claim 2 (depends on 1) The method according to claim 1, wherein the conversion layer is a chromium(III)-based conversion layer. ### Claim 3 (depends on 2) The method according to claim 2, wherein the conversion layer containing chromium(III) is free of chromium(VI). ### Claim 4 (depends on 1) The method according to claim 1, wherein the conversion layer has a corrosion resistance of greater than 72 hours in the salt spray test according to ASTM B117. ### Claim 5 (depends on 1) The method according to claim 1, wherein the metal is selected from the group consisting of aluminum, zinc, magnesium, and alloys of these metals. ### Claim 6 (depends on 1) The method according to claim 1, wherein the cloth comprises a tissue reinforced using polypropylene. ### Claim 7 (depends on 1) The method according to claim 1, wherein the liquid in step (ii) contains at least one chromium(III) compound. ### Claim 8 (depends on 1) The method according to claim 1, wherein the bringing into contact in step (ii) is performed such that at least one of immersing the cloth in a bath containing the liquid containing the at least one active component, and spraying the cloth with the liquid containing the at least one active component occurs. ### Claim 9 (depends on 1) The method according to claim 1, wherein, in a further method step (v), the treated metal surface is wiped with water after the removal of the cloth. ### Claim 10 (depends on 1) The method of claim 1, further comprising affixing the cloth to the metal surface. ### Claim 11 (depends on 1) The method of claim 1, wherein the at least one cloth comprises a plurality of cloths laid abutting or overlapping one another on the metal surface. ### Claim 12 (depends on 11) The method of claim 11, further comprising pressing in the area of the overlap of at least two of the plurality of cloths.