# US 10,501,839 B2 · Methods of removing a ceramic coating from a substrate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,501,839 B2 - Document ID: US10501839B2 - Status: Granted - Kind: B2 - Application number: 15/950,510 - Filed: 2018-04-11 - Published: 2019-10-17 - Granted: 2019-12-10 - Earliest claimed: 2018-04-11 - Assignees: General Electric Company - Applicants: General Electric Company - Inventors: Lawrence Bernard Kool - Web page: https://patentgrep.com/patent/US10501839B2 ## CPC - C23C 8/80: After-treatment - B05D 3/0254: {After-treatment} - B05D 7/14: to metal, e.g. car bodies (involving a chemical reaction between the metal and the coating C23) - C04B 41/009: {characterised by the material treated} - C04B 41/5353: {Wet etching, e.g. with etchants dissolved in organic solvents} - C04B 41/91: involving the removal of part of the materials of the treated articles, e.g. etching - C09K 13/08: containing a fluorine compound - C23C 8/04: Treatment of selected surface areas, e.g. using masks - C23C 8/26: of ferrous surfaces - H01F 41/34: in patterns, e.g. by lithography - H01F 1/147: Alloys characterised by their composition {(treatment thereof for enhancing their electromagnetic properties C21D8/12)} - 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) - B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02) - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ## Abstract A method for removing a ceramic coating from a substrate is presented. The method includes contacting the ceramic coating with a composition including a fluoride source and nitric acid. A method of forming a component having a variation in saturation magnetization is presented. The method includes masking selected portions of a surface of a metallic component using a ceramic coating to form a masked metallic component; selectively diffusing nitrogen into the metallic component by exposing the masked metallic component to a nitrogen-rich atmosphere; and removing the ceramic coating from the surface of the metallic component by contacting the ceramic coating with a composition including the fluoride source and nitric acid. ## Claims ### Claim 1 A method for removing a ceramic coating from a substrate, comprising: applying the ceramic coating as a patterned mask over the substrate to define a masked portion and an unmasked portion thereon, wherein the ceramic coating comprises aluminum silicide, sodium aluminum silicate, potassium aluminum silicate, sodium potassium aluminum silicate, or combinations thereof, and wherein the substrate is a magnetic component; and contacting the ceramic coating with a composition comprising a fluoride source and nitric acid. ### Claim 2 (depends on 1) The method of claim 1, wherein the fluoride source comprises hydrofluoric acid. ### Claim 3 (depends on 1) The method of claim 1, wherein the fluoride source comprises ammonium fluoride, ammonium bifluoride, sodium fluoride, potassium fluoride, lithium fluoride, or combinations thereof. ### Claim 4 (depends on 1) The method of claim 1, wherein an amount of the fluoride source in the composition is in a range from about 5 weight % to about 30 weight %. ### Claim 5 (depends on 1) The method of claim 1, wherein an amount of the nitric acid in the composition is in a range from about 50 weight % to about 95 weight %. ### Claim 6 (depends on 1) The method of claim 1, wherein the ceramic coating is contacted with the composition at a temperature in a range from about 25° C. to about 60° C. ### Claim 7 (depends on 1) The method of claim 1, wherein the ceramic coating is contacted with the composition for a time duration in a range from about 10 min to about 60 min. ### Claim 8 (depends on 1) The method of claim 1, wherein the substrate comprises a metal alloy. ### Claim 9 (depends on 1) The method of claim 1, wherein the ceramic coating comprises the sodium-potassium-aluminum-silicate. ### Claim 10 (depends on 1) The method of claim 1, wherein the ceramic coating includes at least one alkali metal. ### Claim 11 (depends on 10) The method of claim 10, wherein the at least one alkali metal comprises sodium. ### Claim 12 (depends on 10) The method of claim 10, wherein the at least one alkali metal comprises potassium. ### Claim 13 A method for removing a ceramic coating from a substrate, comprising: applying the ceramic coating as a patterned mask over the substrate to define a masked portion and an unmasked portion thereon, wherein the ceramic coating comprises aluminum silicide, sodium aluminum silicate, potassium aluminum silicate, sodium potassium aluminum silicate, or combinations thereof, and wherein the substrate comprises an iron-based alloy; and contacting the ceramic coating with a composition comprising a fluoride source and nitric acid. ### Claim 14 (depends on 13) The method of claim 13, wherein the iron-based alloy includes 14 weight % and 20 weight % chromium and between 2 weight % and 5 weight % of manganese with the balance being iron. ### Claim 15 A method for removing a ceramic coating from a substrate, comprising: applying the ceramic coating as a patterned mask over the substrate to define a masked portion and an unmasked portion thereon, wherein the ceramic coating comprises aluminum silicide, sodium aluminum silicate, potassium aluminum silicate, sodium potassium aluminum silicate, or combinations thereof, exposing the substrate to a nitrogen-rich atmosphere such that nitrogen selectively diffuses into the unmasked portion; and thereafter, contacting the ceramic coating with a composition comprising a fluoride source and nitric acid.