# US 2013/0156958 A1 · Aqueous slurry for the production of thermal and environmental barrier coatings and processes for making and applying the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0156958 A1 - Document ID: US20130156958A1 - Status: Published application - Kind: A1 - Application number: 13/720,571 - Filed: 2012-12-19 - Published: 2013-06-20 - Earliest claimed: 2011-12-19 - Assignees: Praxair S.T. Technology, Inc. - Inventors: Vladimir V. Belov; Irina Belov - Web page: https://patentgrep.com/patent/US20130156958A1 ## CPC - C09D 5/00: Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced {(electrically insulating plastics, resins or waxes H01B3/30)}; Filling pastes - C04B 28/26: Silicates of the alkali metals - C04B 28/344: {the phosphate binder being present in the starting composition solely as one or more phosphates} - C23C 24/08: by application of heat or pressure and heat (C23C24/04 takes precedence) - C23C 24/085: {Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides} - C23C 24/103: {Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides} - E04B 1/78: Heat insulating elements {(E04B1/7662 takes precedence)} - F01D 5/288: {Protective coatings for blades} - C04B 2111/00551: {Refractory coatings, e.g. for tamping} - F05D 2300/2118: Zirconium oxides - F05D 2300/514: Porosity - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) - 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 - 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) - E04B: GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS (border constructions of opening in walls, floors or ceilings E06B1/00; {electromagnetic shielding H05K9/0001}) - 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 ## Abstract An improved slurry formulation for the production of a thermal and environmental barrier coatings are provided which can withstand high temperature applications. The slurry includes a combination of a coarse ceramic powder fraction having close porosity particles and a fine ceramic powder fraction. The combination of the two powders produces a bimodal particle size distribution having a controlled amount of closed porosity that imparts desirable properties to the coating produced. The finer solid particles are interdispersed within an aqueous binder to produce a ceramic matrix with sufficient mechanical strength. The closed porosity containing coarse particles are embedded within the resultant ceramic matrix and do not disintegrate under high temperature conditions to impart a temperature resistant, non-collapsing closed porosity to the coating which can also act as an environmental barrier. ## Claims ### Claim 1 An aqueous slurry composition for production of a porous thermal or environmental barrier coating on a metallic or a ceramic substrate, comprising: a first powder comprising an oxide material with a thermal conductivity lower than about 5 W/m K, coarse particles having a first median size ranging from about 5 microns to about 60 microns, with at least a portion of the coarse particles having a closed porosity that is temperature resistant and substantially impermeable to gas and liquid; a second powder comprising an oxide material with a thermal conductivity lower than about 5 W/m K, the second powder characterized as fine particles having a second median size ranging from about 0.1 to about 5 microns, wherein the second median size is at least about 5 times smaller than the first median size of the first powder, whereby the coarse particles of the first powder and the fine particles of the second powder form a bimodal particle size distribution in the slurry; a plurality of elemental Boron particles provided in an effective amount; and an inorganic binder suspending at least a portion of the plurality of elemental Boron particles, the coarse particles and the fine particles in an aqueous solution; wherein the closed porosity of the coarse particles is temperature resistant and imparts a non-collapsing closed porous structure to the coating. ### Claim 2 (depends on 1) The aqueous slurry composition of claim 1, the first median particle size ranging from about 20 microns to about 50 microns, and the second median particle size ranging from about 1.0 micron to about 4.0 microns, wherein the closed porosity of the coarse particles is no less than 14 percent. ### Claim 3 (depends on 1) The aqueous slurry composition of claim 1, the first median particle size ranging from about 20 microns to about 50 microns, and the second median particle size ranging from about 1.0 micron to about 4.0 microns, wherein the coarse and the fine particles are composed of yttria-stabilized zirconia. ### Claim 4 (depends on 1) The aqueous slurry composition of claim 1, wherein the coarse particles and the fine particles are composed of yttria stabilized zirconia, calcia stabilized zirconia, magnesia stabilized zirconia or mixtures thereof. ### Claim 5 (depends on 1) The aqueous slurry composition of claim 1, wherein the first powder comprises from about 30 wt. % to about 60 wt. % of the aqueous slurry composition, and the first and the second powders in combination comprise a total of at least 55 wt. % up to about 85 wt. % of the aqueous slurry composition. ### Claim 6 (depends on 1) The aqueous slurry composition of claim 1, wherein the binder is selected from the group consisting of a metal silicate binder or a metal phosphate binder. ### Claim 7 (depends on 6) The aqueous slurry composition of claim 6, wherein the binder is a metal silicate binder with a SiO2/M2O ratio higher than about 2.5, wherein M is a metal selected from Na, K and Li or a combination thereof. ### Claim 8 (depends on 6) The aqueous slurry composition of claim 6, wherein the binder is a metal phosphate binder with a P2O5/M ratio of not less than 0.1, wherein M is a metal selected from Group I, II, III or IV of Periodic Chart of Elements or a combination thereof. ### Claim 9 (depends on 1) The aqueous slurry composition of claim 1, further comprising an anticorrosive pigment, a viscosity modifier or a combination thereof. ### Claim 10 (depends on 1) The aqueous slurry composition of claim 1, wherein the fine oxide particles comprise a mixture of oxide compound with a median particle size distribution ranging from about 0.1 microns to about 5 microns, the mixture of the oxide compounds having a pyrochlore-type crystal structure represented by the formula Ln2M2O7, wherein M is Zr, Ce, and/or Hf; and Ln is La, Gd, Sm, Nd, Eu, Yb or any combination thereof. ### Claim 11 (depends on 1) The aqueous slurry composition of claim 1, wherein the fine oxide particles comprise a mixture of oxide compounds having a perovskite-type crystal structure represented by the formula AMO3, and wherein M is Zr and/or Ti; A is an alkali earth element, rare earth element or any combination thereof. ### Claim 12 (depends on 1) The aqueous slurry composition of claim 1, wherein the fine oxide particles are a mixture of oxide compounds comprising aluminates of rare earth metals. ### Claim 13 (depends on 3) The aqueous slurry composition of claim 3, the first powder and the second powder comprise yttria stabilized zirconia, the binder selected from the group consisting of an alkali metal silicate binder and metal phosphate binder, wherein said first powder comprises from 35% to 55% by weight, ratio of the second powder to the first powder is in the range from about 1:1 up to about 1:2.5 by weight, and the first and the second powders combined comprise between about 60% to about 80% by weight of the aqueous slurry composition. ### Claim 14 (depends on 13) The aqueous slurry composition of claim 13 comprising elemental Boron in the amount from 0.2 to 2.0 weight % ### Claim 15 A slurry composition for the production of a thermal or environmental barrier coating comprising: a first ceramic material comprising oxide-based particles having a first median particle size ranging from about 5 microns to about 60 microns, the particles being temperature resistant and substantially impermeable to gas and liquid; a second ceramic material comprising oxide-based particles that are substantially solid, the substantially solid particles having a second median particle size ranging from about 0.1 to about 5 microns; and a binder in combination with at least a portion of the first and the second materials in relative proportions to form a bimodal particle distribution therein; wherein in a cured state the closed porosity of the first ceramic material provides a non-degrading, high temperature stable porous structure to the produced thermal barrier coating ### Claim 16 (depends on 15) The slurry composition of claim 15, further comprising elemental Boron. ### Claim 17 (depends on 15) The aqueous slurry composition of claim 15, wherein a portion of the closed-containing pores of the first ceramic material are submicron sized, nanoscale sized or a mixture thereof. ### Claim 18 (depends on 15) The aqueous slurry composition of claim 15, the first median particle size ranging from about 20 microns to about 50 microns, and the second median particle size ranging from about 1.0 micron to about 4.0 microns. ### Claim 19 (depends on 15) The aqueous slurry composition of claim 15, wherein the first and the second ceramic materials comprise yttria stabilized zirconia. ### Claim 20 A thermal or environmental barrier coating comprising: a glass-ceramic matrix, said matrix is formed by a binder and a fine fraction of powder particles, said particles having a first median particle size; and a plurality of particles having a closed porosity that is non-collapsing at elevated temperatures of at least about 1000° C., and substantially impermeable to gas and liquid, the plurality of closed porosity containing particles having a second median particle size that is substantially non-overlapping with the first median particle size to form a bimodal particle distribution, the second median particle size being at least about five times larger than the first median particle size, wherein the plurality of closed porosity containing particles are dispersed in the glass-ceramic matrix in an effective amount to lower a thermal conductivity of the coating to about 2 W/m K or lower. ### Claim 21 (depends on 20) The coating of claim 20, wherein the plurality of closed porosity containing particles comprise yttria-stabilized zirconia, calcia-stabilized zirconia, magnesia-stabilized zirconia or a mixture thereof. ### Claim 22 (depends on 20) The coating of claim 20, wherein glass-ceramic matrix further comprises Boron. ### Claim 23 (depends on 20) The coating of claim 20, wherein the weight ratio of the closed porosity-containing particles of the coarse fraction to the powder particles of the fine fraction in the bimodal particle size distribution is in the range from about 1:1 to about 2.5:1. ### Claim 24 (depends on 20) The coating of claim 20, wherein the mean particle size of the fine particles is in the range of 1.0-4.0 microns and the mean particle size of the coarse, closed porosity containing particles is in the range of 20-50 microns. ### Claim 25 (depends on 20) The coating of claim 20, wherein the closed porosity of the coarse particles is no less than 14 percent, ### Claim 26 (depends on 20) The coating of claim 20, disposed along a surface of a substrate. ### Claim 27 A method for the production of an aqueous slurry comprising: introducing into an aqueous binder a first powder and a second powder, wherein each of the first and the second powders comprise oxide materials, with a thermal conductivity of not higher than about 5 W/m K, further wherein the first powder is composed of a first plurality of particles comprising closed porosity with a median particle size in the range of about 10 micron to about 60 micron and the second powder is composed of a second plurality of dense particles with a median particle size in the range of about 0.1 micron to about 5.0 micron; forming a bimodal particle size distribution comprising the first plurality of particles and the second plurality of particles, introducing elemental Boron; mixing the first and the second powders and the elemental Boron with the aqueous, mostly inorganic binder to form a particle suspension in the aqueous binder. ### Claim 28 A method for applying a thermal or a environmental barrier coating with an aqueous slurry comprising: providing an aqueous slurry comprising: a first ceramic powder comprising particles having closed porosity and having a first median particle size between about 10 micron to about 60 micron; a second ceramic powder comprising dense particles having a second median particle size between about 0.1 micron to about 5 micron, whereby the first and the second powders form a bimodal particle size distribution; elemental Boron; an aqueous, substantially inorganic binder; applying the aqueous slurry onto a surface of a substrate; and curing the slurry into the coating.