# US 11,111,807 B2 · Abradable layer with glass microballoons > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,111,807 B2 - Document ID: US11111807B2 - Status: Granted - Kind: B2 - Application number: 16/717,458 - Filed: 2019-12-17 - Published: 2020-05-07 - Granted: 2021-09-07 - Earliest claimed: 2017-04-25 - Assignees: Raytheon Technologies Corporation - Applicants: United Technologies Corporation - Inventors: Kevin Seymour; Christopher W. Strock - Web page: https://patentgrep.com/patent/US11111807B2 ## CPC - F01D 11/122: {with erodable or abradable material (blades having cutting or grinding tips F01D5/20)} - C23C 4/134: Plasma spraying - F01D 5/02: Blade-carrying members, e.g. rotors (rotors of non-bladed type F01D1/34; stators F01D9/00 {; selecting particular materials F01D5/28}) - F04D 29/083: {especially adapted for elastic fluid pumps} - F04D 29/324: {Blades} - F05D 2220/32: in gas turbines - F05D 2250/241: spherical - F05D 2300/173: Aluminium alloys, e.g. AlCuMgPb - F05D 2300/177: Ni - Si alloys - F05D 2300/2102: Glass - F05D 2300/6032: Metal matrix composites [MMC] - F05D 2300/61: Syntactic materials, i.e. hollow spheres embedded in a matrix - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - 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) - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A gas turbine engine includes a circumferential row of blades, with the blades having respective blade tips. A seal is disposed about the blades. The seal has an abradable layer which the tips of the blades, at times, rub against when the blades rotate. The rubbing produces a maximum temperature at the abradable layer. The abradable layer includes a metal matrix and microballoons dispersed in the metal matrix. The microballoons are formed of a glass that has a glass transition temperature that is approximately 50° F. to 300° F. greater than the maximum temperature. ## Claims ### Claim 1 A gas turbine engine comprising: a circumferential row of blades, the blades having respective blade tips; and a seal disposed about the blades, the seal having an abradable layer which the tips of the blades, at times, rub against when the blades rotate, there being a maximum temperature at the abradable layer without rubbing, the abradable layer including, a metal matrix, and microballoons dispersed in the metal matrix, the microballoons being formed of a glass having a glass transition temperature that is approximately 50° F. to 300° F. greater than the maximum temperature. ### Claim 2 (depends on 1) The gas turbine engine as recited in claim 1, wherein the metal matrix is formed from an alloy and the alloy is a nickel- or cobalt-based alloy. ### Claim 3 (depends on 1) The gas turbine engine as recited in claim 1, wherein the alloy is copper-based alloy. ### Claim 4 (depends on 1) The gas turbine engine as recited in claim 1, wherein the alloy is aluminum-based alloy. ### Claim 5 (depends on 1) The gas turbine engine as recited in claim 1, wherein the glass is fluoroaluminate glass. ### Claim 6 (depends on 1) The gas turbine engine as recited in claim 1, wherein the glass is tellurium dioxide glass. ### Claim 7 (depends on 1) The gas turbine engine as recited in claim 1, wherein the glass is borosilicate glass. ### Claim 8 (depends on 1) The gas turbine engine as recited in claim 1, wherein the glass is soda-lime glass. ### Claim 9 (depends on 1) The gas turbine engine as recited in claim 1, wherein the glass is fused quartz glass. ### Claim 10 (depends on 1) The gas turbine engine as recited in claim 1, wherein the abradable layer has, by volume, 10-60% of the microballoons. ### Claim 11 (depends on 1) The gas turbine engine as recited in claim 1, wherein the abradable layer further comprises a lubricant. ### Claim 12 (depends on 1) The gas turbine engine as recited in claim 1, wherein the circumferential row of blades are part of a compressor or turbine section of the gas turbine engine. ### Claim 13 (depends on 11) The gas turbine engine as recited in claim 11, wherein the lubricant is boron nitride. ### Claim 14 (depends on 13) The gas turbine engine as recited in claim 13, wherein the abradable layer includes up to about 10% by volume of boron nitride particles. ### Claim 15 (depends on 2) The glass turbine engine as recited in claim 2, wherein the alloy is MCrAlY, wherein M is either cobalt or nickel. ### Claim 16 (depends on 15) The gas turbine engine as recited in claim 15, wherein a combined amount of aluminum and chromium is greater than 15% by weight. ### Claim 17 (depends on 3) The gas turbine engine as recited in claim 3, wherein the alloy includes at least 35% of copper by weight. ### Claim 18 (depends on 4) The gas turbine engine as recited in claim 4, wherein the alloy is a eutectic composition having 12% silicon by weight. ### Claim 19 (depends on 4) The gas turbine engine as recited in claim 4, wherein the alloy is a Cu—Ni—Cr—Al alloy.