# US 8,770,926 B2 · Rough dense ceramic sealing surface in turbomachines > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,926 B2 - Document ID: US8770926B2 - Status: Granted - Kind: B2 - Application number: 12/910,973 - Filed: 2010-10-25 - Published: 2012-04-26 - Granted: 2014-07-08 - Earliest claimed: 2010-10-25 - Assignees: United Technologies Corporation - Applicants: Changsheng Guo; Christopher W. Strock; Thomas W. Stowe; Paul W. Baumann - Inventors: Changsheng Guo; Christopher W. Strock; Thomas W. Stowe; Paul W. Baumann - Web page: https://patentgrep.com/patent/US8770926B2 ## CPC - C23C 4/18: After-treatment - C23C 4/073: containing MCrAl or MCrAlY alloys, where M is nickel, cobalt or iron, with or without non-metal elements - C23C 4/11: Oxides - C23C 30/00: Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process (C23C26/00, C23C28/00 take precedence) - F01D 11/122: {with erodable or abradable material (blades having cutting or grinding tips F01D5/20)} - F05D 2230/14: Micromachining - F05D 2230/31: Layer deposition - F05D 2230/90: Coating; Surface treatment - F05D 2300/21: Oxide ceramics - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - Y10T 428/24355: Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.] - 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) - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract An abrasive coating is formed on a rotor shaft that rotates with respect to cantilevered vanes. The coating is formed by thermal spray techniques and comprises a ceramic layer on a metal bond coat. The coating surface is roughened by crush grinding or by grit blasting to increase the abradability of the surface. ## Claims ### Claim 1 A method of conditioning a dense ceramic coating to form an abrasive seal comprising: forming a part with a surface; depositing a bond coat on the surface; depositing a ceramic coating on the bond coat; grinding the ceramic surface to a surface finish of 20 to 30 microinches (0.51 microns to 0.76 microns); and roughening the ceramic surface to a roughness from about 100 Ra in microinches to about 300 Ra (2540 Ra to 7620 Ra in microns) to form an abrasive seal. ### Claim 2 (depends on 1) The method of claim 1 wherein the bond coat is MCrAlY where M is Ni or Co or alloys thereof. ### Claim 3 (depends on 2) The method of claim 2 wherein the bond coat is deposited by air plasma spraying. ### Claim 4 (depends on 1) The method of claim 1 wherein the ceramic coating is zirconia containing yttria. ### Claim 5 (depends on 4) The method of claim 4 wherein the yttria stabilized zirconia contains 11-14 wt. % yttria. ### Claim 6 (depends on 1) The method of claim 1 wherein the ceramic surface is roughened by crush grinding. ### Claim 7 (depends on 1) The method of claim 1 wherein the ceramic surface is roughened by grit blasting. ### Claim 8 An abrasive coating for a rotor that moves relative to cantilevered vanes, the coating comprising: a metal bond coat layer on the rotor shaft; a ceramic layer on the metal bond coat layer providing thermal insulation of the rotor; and a roughened surface on the ceramic layer for abrading bare vane tips that contact the rotor during operation with a roughness of from about 100 Ra to about 300 Ra in microinches (2540 Ra to 7620 Ra in microns). ### Claim 9 (depends on 8) The abrasive coating of claim 8 wherein the metal bond layer ranges in thickness between about 3 mils (76 microns) to about 7 mils (178 microns). ### Claim 10 (depends on 8) The abrasive coating of claim 8 wherein the metal bond layer is formed of a nickel aluminum alloy, MCrAl, or MCrAlY wherein M is nickel, iron, cobalt, or alloys thereof. ### Claim 11 (depends on 10) The abrasive coating of claim 10 wherein the metal bond layer is formed of 15-40 wt % Cr, 6-15 wt % Al, 0.6-1.0 wt % Y and the balance nickel, iron, cobalt, or combinations thereof. ### Claim 12 (depends on 10) The abrasive coating of claim 10 wherein the ceramic layer is yttria stabilized zirconia containing 11-14 wt. % yttria. ### Claim 13 (depends on 12) The abrasive coating of claim 12 wherein the ceramic layer is zirconia containing 12 weight percent yttria. ### Claim 14 (depends on 12) The abrasive coating of claim 12 wherein the ceramic layer ranges in thickness between about 3 mils (76 microns) and 25 mils (635 microns). ### Claim 15 A compressor for a gas turbine engine comprising: a rotor having a plurality of blades extending radially outward from the rotor; a plurality of cantilevered vanes between the rotor blades and extending radially inward toward the rotor; and a coating on the portion of the rotor facing bare vane tips of the vanes, the coating including a metal bond coat layer on the outer surface, a ceramic layer over the bond layer, and an abrasive surface on the ceramic layer with a surface roughness of from about 100 Ra to about 300 Ra in microinches (2540 Ra to 7620 Ra in microns), whereby the ceramic layer provides insulation of the rotor shaft during operation and abrades the bare vane tips during rub interaction events. ### Claim 16 (depends on 15) The compressor of claim 15 wherein the first metal bond layer is a nickel aluminum alloy, MCrAl, or MCrAlY wherein M is nickel, iron, cobalt, or alloys thereof. ### Claim 17 (depends on 15) The compressor of claim 15 wherein the ceramic layer is zirconia containing 11-14 wt. % yttria. ### Claim 18 (depends on 15) The compressor of claim 15 wherein the abrasive surface on the ceramic layer is produced by crush grinding. ### Claim 19 (depends on 15) The compressor of claim 15 wherein the abrasive surface on the ceramic layer is produced by grit blasting.