# US 9,435,047 B2 · Process for corrosion protection of iron containing materials > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,435,047 B2 - Document ID: US9435047B2 - Status: Granted - Kind: B2 - Application number: 14/647,458 - Filed: 2014-01-07 - Published: 2016-01-07 - Granted: 2016-09-06 - Earliest claimed: 2013-03-26 - Assignees: Atotech Deutschland GmbH - Applicants: Atotech Deutschland GmbH - Inventors: Björn Dingwerth; Mike Krüger - Web page: https://patentgrep.com/patent/US9435047B2 ## CPC - C25D 3/565: {containing more than 50% by weight of zinc} - C23C 22/83: Chemical after-treatment - C25D 5/48: After-treatment of electroplated surfaces - C23C 2222/10: Use of solutions containing trivalent chromium but free of hexavalent chromium - C25D 5/14: two or more layers being of nickel or chromium, e.g. duplex or triplex layers - C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR - 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 process for corrosion protection of an iron-containing substrate wherein a first zinc-nickel alloy layer, a second zinc-nickel alloy layer and a black passivate layer are deposited onto the substrate. The nickel concentration in the second zinc-nickel alloy layer is higher than the nickel concentration in the first zinc-nickel alloy layer. The substrate surface obtained is homogenously black with an appealing decorative appearance and both resistance against white rust and red rust are improved. ## Claims ### Claim 1 A process for corrosion protection of an iron-containing substrate comprising, in this order, the steps of (i) providing a substrate made of an iron-containing material, (ii) electroplating onto said substrate a first zinc-nickel alloy layer having a nickel concentration in the range of 6 to 15 wt.-%, (iii) thereon, electroplating a second zinc-nickel alloy layer having a nickel concentration in the range of 12 to 30 wt.-% onto the first zinc-nickel alloy layer with the proviso that the concentration of nickel in the second zinc-nickel alloy layer is higher than the nickel concentration in the first zinc-nickel alloy layer, and (iv) depositing a black passivation layer onto the second zinc-nickel alloy layer, wherein an acidic zinc-nickel electrolyte used for electroplating the first zinc-nickel alloy layer and an acidic zinc-nickel electrolyte used for electroplating the second zinc-nickel alloy layer are the same acidic zinc-nickel electrolyte and wherein the nickel concentrations in both zinc-nickel alloy layers are adjusted by changing pH value, temperature, or both the pH value and the temperature of one or both of the acidic zinc-nickel electrolyte used for electroplating the first zinc-nickel alloy layer and the acidic zinc-nickel electrolyte used for electroplating the second zinc-nickel alloy layer during the electroplating steps. ### Claim 2 (depends on 1) The process for corrosion protection of a substrate according to claim 1 wherein the substrate is made of cast iron. ### Claim 3 (depends on 1) The process for corrosion protection of a substrate according to claim 1 wherein the concentration of nickel in the first zinc-nickel alloy layer ranges from 10 to 15 wt.-%. ### Claim 4 (depends on 1) The process for corrosion protection of a substrate according to claim 1 wherein the concentration of nickel in the first zinc-nickel alloy layer ranges from 12 to 15 wt.-%. ### Claim 5 (depends on 1) The process for corrosion protection of a substrate according to claim 1 wherein the concentration of nickel in the second zinc-nickel alloy layer ranges from 13 to 20 wt.-%. ### Claim 6 (depends on 1) The process for corrosion protection of a substrate according to claim 1 wherein the concentration of nickel in the second zinc-nickel alloy layer ranges from 15 to 18 wt.-%. ### Claim 7 (depends on 1) The process for corrosion protection of a substrate according to claim 1 wherein the concentration represented in weight-% of nickel in the first zinc-nickel alloy layer is 50 to 99% of the concentration represented in weight-% of nickel in the second zinc-nickel alloy layer. ### Claim 8 (depends on 1) The process for corrosion protection of a substrate according to claim 1 wherein the concentration represented in weight-% of nickel in the first zinc-nickel alloy layer is 60 to 95% of the concentration represented in weight-% of nickel in the second zinc-nickel alloy layer. ### Claim 9 (depends on 1) The process for corrosion protection of a substrate according to claim 1 wherein the concentration represented in weight-% of nickel in the first zinc-nickel alloy layer is 70 to 90% of the concentration represented in weight-% of nickel in the second zinc-nickel alloy layer. ### Claim 10 (depends on 1) The process for corrosion protection of a substrate according to claim 1 wherein the black passivation layer is deposited from an acidic aqueous solution comprising chromium(III) ions, a complexing agent and an oxidizing agent. ### Claim 11 (depends on 1) The process for corrosion protection of a substrate according to claim 1 wherein at least one further layer selected from sealing layer and non pigmented chromium(III) containing passivation layer is deposited onto the black passivate layer obtained in step (iv).