# US 2021/0340659 A1 · Activation of self-passivating metals using reagent coatings for low temperature nitrocarburization > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0340659 A1 - Document ID: US20210340659A1 - Status: Published application - Kind: A1 - Application number: 17/242,555 - Filed: 2021-04-28 - Published: 2021-11-04 - Earliest claimed: 2020-04-29 - Assignees: Swagelok Company - Applicants: Swagelok Company - Inventors: Christina Semkow; Cyprian Adair William Illing; Peter C. Williams; Wayne Ostrosky - Web page: https://patentgrep.com/patent/US20210340659A1 ## CPC - C23C 8/02: Pretreatment of the material to be coated (C23C8/04 takes precedence) - C23C 8/04: Treatment of selected surface areas, e.g. using masks - C23C 8/08: only one element being applied - C23C 8/24: Nitriding - C23C 8/30: Carbo-nitriding - C23C 8/32: of ferrous surfaces - C23C 8/42: only one element being applied - C23C 8/64: Carburising - C23C 8/80: After-treatment - 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 A method for treating a workpiece made of self-passivating metal and having a Beilby layer including applying a coating to a surface of the workpiece, the coating including a reagent, treating the coating to thermally alter the reagent, wherein the thermal altering of the reagent activates and/or hardens the surface. ## Claims ### Claim 1 A method for treating a workpiece made of self-passivating metal and having a Beilby layer including: applying a coating to at least a portion of a surface of the workpiece, the coating including a reagent; and treating the coating to thermally alter the reagent, wherein the thermal altering of the reagent activates the surface for hardening. ### Claim 2 (depends on 1) The method of claim 1, wherein the treating the coating includes heating to a temperature that decomposes the reagent. ### Claim 3 (depends on 1) The method of claim 1, further including hardening the surface. ### Claim 4 (depends on 3) The method of claim 3, wherein the hardening includes at least one of nitriding, carburizing, nitrocarburizing, and carbonitriding. ### Claim 5 (depends on 3) The method of claim 3, wherein the thermal altering the reagent supplies at least one of nitrogen and carbon for the hardening. ### Claim 6 (depends on 1) The method of claim 1, wherein: the surface is one of a plurality of surfaces on the workpiece; and applying the coating includes applying the coating selectively to the surface but not to one or more of the other surfaces of the plurality of surfaces on the workpiece. ### Claim 7 (depends on 1) The method of claim 1, wherein applying the coating includes applying the coating selectively to a portion of the surface. ### Claim 8 (depends on 1) The method of claim 1, wherein the coating is at least one of a powder coating, electrostatic powder coating, fluidized bed, and centrifugal force-controlled spin coating. ### Claim 9 (depends on 8) The method of claim 8, wherein the coating includes a polymer with a staged, non-reacted monomer. ### Claim 10 (depends on 9) The method claim 9, wherein the polymer is melamine. ### Claim 11 (depends on 8) The method of claim 8, wherein the reagent is associated with HCl when in the powder. ### Claim 12 (depends on 1) The method of claim 1, wherein the coating is water based. ### Claim 13 (depends on 12) The method of claim 12, wherein the coating includes a vehicle including at least one of water, water-based polyethylene oxide coating, water-based polyvinyl acetate coating, and a water-based polypropylene oxide coating. ### Claim 14 (depends on 12) The method of claim 12, further including drying the coating. ### Claim 15 (depends on 14) The method of claim 14, wherein drying the coating removes the vehicle from the coating. ### Claim 16 (depends on 1) The method of claim 1, wherein the coating is oil based. ### Claim 17 (depends on 16) The method of claim 16, wherein the oil includes at least one of mineral oil, finely distilled oil, food-grade oil, a paraffinic oil, a hydrocarbon based machining oil, and an emulsion based machining oil. ### Claim 18 (depends on 17) The method of claim 17, wherein the oil is evaporated in a furnace to leave the reagent. ### Claim 19 (depends on 18) The method of claim 18, wherein the evaporating includes at least one of: applying a vacuum; and evaporating at a temperature below an activation or hardening temperature of the reagent. ### Claim 20 (depends on 16) The method of claim 16, wherein the oil does not chemically interfere with an activation or hardening process. ### Claim 21 (depends on 16) The method of claim 16, wherein HCl is complexed with the reagent. ### Claim 22 (depends on 1) The method of claim 1, wherein the coating is liquid or molten. ### Claim 23 (depends on 1) The method of claim 1, wherein the coating is deposition based. ### Claim 24 (depends on 1) The method of claim 1, wherein the coating is solvent based. ### Claim 25 (depends on 1) The method of claim 1, wherein the reagent includes an oxygen-free nitrogen halide salt. ### Claim 26 (depends on 1) The method of claim 1, wherein the reagent includes a non-polymeric N/C/H compound. ### Claim 27 (depends on 1) The method of claim 1, wherein the surface includes a passivation layer. ### Claim 28 (depends on 1) The method of claim 1, wherein the reagent includes at least one of Dimethylbiguanide HCl, Guanidine HCl, Biguanide HCl, Bis(diaminomethylidene)guanidine HCl, Carbamimidoylimidodicarbonimidic diamide HCl, or Melamine HCl. ### Claim 29 (depends on 1) The method of claim 1, wherein the coating includes a petroleum distillate. ### Claim 30 (depends on 29) The method of claim 29, further including evaporating the petroleum distillate to leave a dry mixture of the reagent. ### Claim 31 (depends on 1) A workpiece having a Beilby layer treated according to the method of claim 1. ### Claim 32 (depends on 31) The workpiece of claim 31, wherein the applying a coating includes providing the reagent as part of a paraffinic oil. ### Claim 33 (depends on 32) The workpiece of claim 32, wherein the paraffinic oil is hydrocarbon or emulsion based. ### Claim 34 (depends on 32) The workpiece of claim 32, wherein the paraffinic oil is evaporated in a furnace to leave the reagent and modify the portion. ### Claim 35 (depends on 34) The workpiece of claim 34, wherein the evaporating includes applying a vacuum. ### Claim 36 (depends on 34) The workpiece of claim 34, wherein the evaporating is performed at a temperature below an activation or hardening temperature of the reagent. ### Claim 37 (depends on 32) The workpiece of claim 32, wherein the paraffinic oil does not chemically interfere with an activation or hardening process. ### Claim 38 A coating composition for treating a workpiece made of self-passivating metal and having a Beilby layer comprising: a reagent vehicle; and a reagent comprising a guanidine [HNC(NH2)2] moiety and associated with HCl to activate the Beilby layer for low temperature interstitial surface hardening. ### Claim 39 (depends on 38) The coating composition of claim 38, wherein the reagent includes at least one of an oxygen-free nitrogen halide salt and a non-polymeric N/C/H compound. ### Claim 40 (depends on 38) The coating composition of claim 38, wherein the reagent vehicle includes at least one of a powder, a water-based liquid, an oil, and a solvent. ### Claim 41 A method for treating a workpiece made of self-passivating metal and having a Beilby layer including: applying a coating to at least a portion of a surface of the workpiece, wherein the coating substantially prevents carburizing, nitriding, or nitrocarburizing of the portion; and one or more of carburizing, nitriding, or nitrocarburizing the workpiece to harden the workpiece. ### Claim 42 (depends on 41) The method of claim 41, wherein the coating is copper or another metal. ### Claim 43 (depends on 41) The method of claim 41, further include thermally treating a reagent to activate uncoated portions of the workpiece for the one or more of carburizing, nitriding, or nitrocarburizing the workpiece to harden the workpiece. ### Claim 44 (depends on 41) The method of claim 41, wherein the reagent includes at least one of Dimethylbiguanide HCl, Guanidine HCl, Biguanide HCl, Bis(diaminomethylidene)guanidine HCl, Carbamimidoylimidodicarbonimidic diamide HCl, or Melamine HCl.