# US 2013/0157040 A1 · System and method for utilization of shrouded plasma spray or shrouded liquid suspension injection in suspension plasma spray processes > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0157040 A1 - Document ID: US20130157040A1 - Status: Published application - Kind: A1 - Application number: 13/715,189 - Filed: 2012-12-14 - Published: 2013-06-20 - Earliest claimed: 2011-12-14 - Inventors: Christopher A. Petorak; Don J. Lemen; Albert Feuerstein; Thomas F. Lewis, III; Mark McCoy - Web page: https://patentgrep.com/patent/US20130157040A1 ## CPC - B05B 7/205: {the material to be sprayed being originally a particulate material} - C23C 4/12: characterised by the method of spraying - C23C 4/123: Spraying molten metal - C23C 4/134: Plasma spraying - Y10T 428/25: Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles - B05B: SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES (spray-mixers with nozzles B01F25/72; processes for applying liquids or other fluent materials to surfaces by spraying B05D) - 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) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A system and method for producing thermal spray coatings on a substrate from a liquid suspension is disclosed. The disclosed system and method include a thermal spray torch for generating a plasma and a liquid suspension delivery subsystem for delivering a flow of liquid suspension with sub-micron particles to the plasma to produce a plasma effluent. The liquid suspension delivery subsystem comprises an injector or nozzle which can produce an inert or reactive gas sheath partially or fully surrounding the plasma effluent. A sheath can also be used to isolate injection of the liquid suspension. A gas assist stream can also be employed at or near the suspension injection point. The shroud, sheath or gas assist technique can retain the sub-micron particles entrained within the plasma effluent and substantially prevent entrainment of ambient gases into the plasma effluent. The liquid suspension delivery subsystem can be arranged as an axial injection system, a radial internal injection system or an external radial injection system. ## Claims ### Claim 1 A thermal spray system for producing coatings on a substrate from a liquid suspension comprising: a thermal spray torch for generating a plasma; a liquid suspension delivery subsystem for delivering a flow of the liquid suspension with sub-micron particles; and a nozzle assembly for delivering the plasma from the thermal spray torch to the liquid suspension to produce a plasma effluent, the nozzle assembly adapted for producing an inert gas shroud substantially surrounding said plasma effluent; wherein the inert shroud is configured to substantially retain entrainment of the sub-micron particles in the plasma effluent and substantially inhibit gases from entering and reacting with the plasma effluent. ### Claim 2 (depends on 1) The thermal spray system of claim 1, wherein the shroud extends from the nozzle assembly to the substrate surface. ### Claim 3 (depends on 1) The thermal spray system of claim 1, wherein the shroud is a laminar flowing shield. ### Claim 4 (depends on 1) The thermal spray system of claim 1, wherein the shroud has an axial distance less than a distance from the nozzle to the substrate surface. ### Claim 5 (depends on 4) The thermal pray system of claim 4, wherein the shroud diverges in a direction towards the substrate. ### Claim 6 (depends on 4) The thermal pray system of claim 4, wherein the shroud converges in a direction towards the substrate. ### Claim 7 (depends on 1) The thermal spray system of claim 1, wherein the liquid suspension delivery subsystem comprises an injector adapted to produce an inert or reactive gas sheath surrounding the flow of the liquid suspension. ### Claim 8 (depends on 1) The thermal spray system of claim 1, wherein the liquid suspension system is configured external to the nozzle. ### Claim 9 (depends on 1) The thermal spray system of claim 1, wherein the liquid suspension system is configured internal to the nozzle. ### Claim 10 (depends on 1) The thermal spray system of claim 1, wherein the liquid suspension system is configured internal to the nozzle so as to deliver an axial flow of the liquid suspension. ### Claim 11 (depends on 8) The thermal spray system of claim 8, wherein the liquid suspension system further comprises a gas assist stream proximate to and contemporaneously with the liquid suspension system. ### Claim 12 A method of producing coatings on a substrate using a liquid suspension with sub-micron particles dispersed therein, the method comprising the steps of: generating a plasma from a thermal spray torch; delivering a flow of liquid suspension with sub-micron particles dispersed therein to the plasma or in close proximity thereto to produce a plasma effluent stream; surrounding the flow of the effluent stream with an inert gas shroud to produce a shrouded effluent; retaining the sub-micron particles entrained within the shrouded effluent; and directing the shrouded effluent with the sub-micron particles contained therein towards the substrate to coat the substrate. ### Claim 13 (depends on 12) The method of claim 12, further comprising the step of—substantially preventing entrainment of gases into the shrouded effluent. ### Claim 14 (depends on 12) The method of claim 12, further comprising the step of fragmenting droplets of the liquid suspension across the shroud. ### Claim 15 (depends on 12) The method of claim 12, further comprising the steps of: selectively removing the shroud at a predetermined axial distance away from the substrate surface; introducing ambient gases at the predetermined axial distance and downstream thereof; oxidizing a portion of the sub-micron particles. ### Claim 16 (depends on 15) The method of claim 15, further comprising the step of converging the shroud at the predetermined axial distance. ### Claim 17 (depends on 15) The method of claim 15, further comprising the step of diverging the shroud away from the effluent stream to allow the introduction of ambient gases at the predetermined axial distance. ### Claim 18 (depends on 12) The method of claim 12, further comprising the step of surrounding the liquid suspension with a gas sheath. ### Claim 19 (depends on 18) The method of claim 18, further comprising the step of introducing a stream of gas injected proximate to and contemporaneously with the suspension injection. ### Claim 20 (depends on 18) The method of claim 18, wherein the sub-micron particles have an average particle size of 10 microns lower. ### Claim 21 (depends on 12) A coating deposited on the substrate prepared according to the process of claim 12.