# US 2019/0169753 A1 · Method for reducing surface roughness > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0169753 A1 - Document ID: US20190169753A1 - Status: Published application - Kind: A1 - Application number: 16/205,926 - Filed: 2018-11-30 - Published: 2019-06-06 - Earliest claimed: 2017-12-01 - Assignees: General Electric Company - Applicants: General Electric Company - Inventors: Wusheng Xu; Laura C. Laura; Lawrence Bernard Kool; Dalong Zhong; Hong Zhou - Web page: https://patentgrep.com/patent/US20190169753A1 ## CPC - C23C 26/00: Coating not provided for in groups C23C2/00 - C23C24/00 - B33Y 40/20: Post-treatment, e.g. curing, coating or polishing - C23C 10/48: Aluminising - C23C 10/60: After-treatment - C23F 1/00: Etching metallic material by chemical means (manufacture of printing surfaces B41C; manufacture of printed circuits H05K) - C23F 1/10: Etching compositions (C23F1/44 takes precedence) - C23F 1/14: Aqueous compositions - C23F 1/16: Acidic compositions (C23F1/42 takes precedence) - C23F 1/20: for etching aluminium or alloys thereof - H10P 14/40: of conductive or resistive materials - H10P 14/693: {the material containing hafnium, e.g. HfSiOx or HfSiON} - H10P 14/69391: {the material containing aluminium, e.g. Al2O3} - H10P 50/264: {by chemical means} - H10P 50/667: {by liquid etching only} - 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) - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING - C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25 - H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10 ## Abstract A surface of an article is modified by aluminizing an initial surface at a first temperature to form a first aluminized layer and a sublayer, removing at least a portion of the first aluminized layer, aluminizing the sublayer at a second temperature to form a second aluminized layer, and finally removing at least a portion of the second aluminized layer to form a processed surface. The second temperature is less than the first temperature and a roughness of the processed surface is less than the roughness of the initial surface. ## Claims ### Claim 1 A method comprising (a) aluminizing an initial surface at a first temperature to form a first aluminized layer and a sublayer; (b) removing at least a portion of the first aluminized layer to expose the sublayer; (c) aluminizing the sublayer at a second temperature to form a second aluminized layer, wherein the second temperature is less than the first temperature; and (d) removing at least a portion of the second aluminized layer to form a processed surface, wherein a roughness of the processed surface is less than the roughness of the initial surface. ### Claim 2 (depends on 1) The method of claim 1, wherein a thickness of the first aluminized layer is greater than 100 micrometers. ### Claim 3 (depends on 1) The method of claim 1, wherein the sublayer is in between a non-aluminized bulk portion and the first aluminized layer. ### Claim 4 (depends on 1) The method of claim 1, wherein the sublayer comprises a sigma phase. ### Claim 5 (depends on 1) The method of claim 1, wherein the first temperature is greater than 1000 degrees Celsius. ### Claim 6 (depends on 1) The method of claim 1, wherein the second temperature is less than 800 degrees Celsius. ### Claim 7 (depends on 1) The method of claim 1, wherein the initial surface is a cobalt-rich surface. ### Claim 8 (depends on 1) The method of claim 1, wherein aluminizing the initial surface comprises coating with a first slurry comprising aluminum and aluminum oxide. ### Claim 9 (depends on 8) The method of claim 8, wherein an amount of aluminum oxide in the first slurry is greater than 20 weight percentage of the first slurry. ### Claim 10 (depends on 1) The method of claim 1, wherein aluminizing the sublayer comprises coating with a second slurry comprising aluminum. ### Claim 11 (depends on 1) The method of claim 1, wherein removing the first aluminized layer, removing the second aluminized layer, or removing both the first aluminized layer and the second aluminized layer comprises acid etching. ### Claim 12 (depends on 1) The method of claim 1, wherein the roughness of the processed surface is less than about 60% of the roughness of the initial surface. ### Claim 13 (depends on 1) The method of claim 1, further comprising iterating at least once the steps a, b, c, and d. ### Claim 14 A method comprising (a) coating an initial surface using a first slurry to form a coated surface; (b) heat-treating the coated surface at a first temperature to form a first aluminized layer and a sublayer; (c) removing at least a portion of the first aluminized layer by acid etching to expose the sublayer; (d) coating the sublayer using a second slurry to form a coated sublayer; (e) heat-treating the coated sublayer at a second temperature to form a second aluminized layer, wherein the second temperature is less than the first temperature; and (f) removing at least a portion of the second aluminized layer by acid etching to form a processed surface, wherein a roughness of the processed surface is less than the roughness of the initial surface. ### Claim 15 (depends on 14) The method of claim 14, wherein the first slurry comprises aluminum, aluminum oxide, and ammonium chloride. ### Claim 16 (depends on 14) The method of claim 14, wherein the second slurry comprises aluminum and ammonium chloride. ### Claim 17 (depends on 14) The method of claim 14, wherein the first temperature is greater than 1000 degrees Celsius. ### Claim 18 (depends on 14) The method of claim 14, wherein the second temperature is less than 800 degrees Celsius. ### Claim 19 A method comprising (a) aluminizing an initial cobalt-rich surface at a temperature greater than 1000 degrees Celsius to form a first aluminized layer and a sublayer; (b) removing at least a portion of the first aluminized layer to expose the sublayer; (c) aluminizing the sublayer at a temperature less than 800 degrees Celsius to form a second aluminized layer; and (d) removing at least a portion of the second aluminized layer to form a processed cobalt-rich surface, wherein a roughness of the processed cobalt-rich surface is less than the roughness of the initial cobalt-rich surface. ### Claim 20 (depends on 19) The method of claim 19, wherein an amount of cobalt in the initial cobalt-rich surface is greater than 60 atomic percentage.