# US 10,871,256 B2 · Property enhancement of surfaces by electrolytic micro arc oxidation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,256 B2 - Document ID: US10871256B2 - Status: Granted - Kind: B2 - Application number: 14/810,155 - Filed: 2015-07-27 - Published: 2017-02-02 - Granted: 2020-12-22 - Earliest claimed: 2015-07-27 - Assignees: Schlumberger Technology Corporation - Applicants: Schlumberger Technology Corporation - Inventors: You Lu; Manuel P. Marya; Virendra Singh; Tatiana Reyes Ayers - Web page: https://patentgrep.com/patent/US10871256B2 ## CPC - F16L 58/08: by metal - C23C 16/06: characterised by the deposition of metallic material - C23C 16/56: After-treatment - C23C 28/32: {including at least one pure metallic layer} - C23C 28/321: {with at least one metal alloy layer} - C23C 28/322: {only coatings of metal elements only} - C23C 28/345: {with at least one oxide layer} - C25D 5/48: After-treatment of electroplated surfaces - C25D 7/04: Tubes; Rings; Hollow bodies - C25D 11/022: {Anodisation on selected surface areas} - C25D 11/024: {Anodisation under pulsed or modulated current or potential} - C25D 11/026: {Anodisation with spark discharge} - C25D 11/04: of aluminium or alloys based thereon - C25D 11/06: characterised by the electrolytes used - C25D 11/246: {for sealing layers} - C25D 11/26: of refractory metals or alloys based thereon - C25D 11/30: of magnesium or alloys based thereon - E21B 17/1085: {Wear protectors; Blast joints; Hard facing} - F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL - 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) - C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract Embodiments of the present technology may include a tubular product for oilfield applications. The tubular product may include a tubular substrate, which may include a ferrous alloy. The tubular substrate may have an inner surface characterized by an inner diameter and an outer surface characterized by an outer diameter. The tubular product may also include a first layer deposited over at least one of the inner surface or the outer surface. The first layer may include aluminum. The tubular product may further include a second layer, which may include aluminum oxide formed by micro arc oxidation of a portion of the first layer. ## Claims ### Claim 1 A tubular product for oilfield applications, the tubular product comprising: a tubular substrate comprising a ferrous alloy, wherein the tubular substrate has an inner surface characterized by an inner diameter and an outer surface characterized by an outer diameter; a first layer deposited directly onto at least one of the inner surface or the outer surface of the tubular substrate, wherein the first layer comprises aluminum; a second layer being between 1 μm and 40 μm thick and comprising aluminum oxide formed by micro arc oxidation of a portion of the first layer, wherein the second layer comprises an amount of aluminum oxide that is stoichiometrically equivalent to an amount of aluminum oxidized in the first layer, and wherein the second layer defines a plurality of pores, including at least one pore extending into the first layer; and a third layer filling the plurality of pores in the second layer, wherein the portion of the at least one pore in the first layer is filled with the third layer. ### Claim 2 (depends on 1) The tubular product of claim 1, wherein nanoparticles are embedded in the second layer. ### Claim 3 (depends on 2) The tubular product of claim 2, wherein the nanoparticles include a material selected from the group consisting of tungsten carbide, silicon carbide, boron carbide, silicon nitride, aluminum nitride, cubic boron nitride, a carbon nanotube (CNT), graphene nano platelet, and reduced graphene oxide. ### Claim 4 (depends on 2) The tubular product of claim 2, wherein the nanoparticles comprise a H2S sensing material. ### Claim 5 A tubular product for oilfield applications, the tubular product, comprising: a tubular substrate comprising a ferrous alloy, wherein the tubular substrate has an inner surface characterized by an inner diameter and an outer surface characterized by an outer diameter; a first layer deposited directly onto at least one of the inner surface or the outer surface of the tubular substrate, wherein the first layer comprises aluminum; a second layer being between 1 μm and 50 μm thick and comprising aluminum oxide formed by micro arc oxidation of a portion of the first layer, wherein the second layer comprises an amount of aluminum oxide that is stoichiometrically equivalent to an amount of aluminum oxidized in the first layer, and wherein nanoparticles are embedded in the second layer, the nanoparticles comprising a H2S sensing material comprising CuO—SnO2 Core/Shell PN-Junction nanorods, CuO modified SnO2 nanoribbons, CuO doped SnO2 nanowires, WO3 nanoparticle, or ZnO nanorods. ### Claim 6 (depends on 2) The tubular product of claim 2, wherein the tubular product has greater corrosion resistance than the tubular substrate without the first layer and the second layer. ### Claim 7 (depends on 1) The tubular product of claim 1, wherein the inner diameter is greater than or equal to about 0.25 inches and less than or equal to about 6 inches. ### Claim 8 (depends on 1) The tubular product of claim 1, wherein the tubular product is characterized by a length, and the length is between about 18 feet and about 25 feet. ### Claim 9 An oilfield tubular comprising: a substrate comprising a ferrous alloy; a first layer directly on a surface of the substrate, wherein the first layer comprises aluminum deposited by a thermal spray process, a cold spray process, a hot dip aluminizing (liquid) process, a vapor aluminizing process, a plasma and ion deposition process, or an electrolytic deposition process; and a second layer over a second portion of the first layer, wherein the second layer is between 1 μm and 40 μm thick and comprises aluminum oxide, and wherein the second layer is formed by oxidizing a first portion of the first layer by micro arc oxidation, wherein the second layer comprises an amount of aluminum oxide that is stoichiometrically equivalent to an amount of aluminum oxidized in the first layer, and wherein the second layer defines a plurality of pores, including at least one pore extending into the first layer; and a third layer filling the plurality of pores in the second layer, wherein the portion of the at least one pore in the first layer is filled with the third layer. ### Claim 10 (depends on 9) The oilfield tubular of claim 9, wherein formation of the second layer includes immersing the substrate and the first layer in an alkaline electrolytic liquid bath. ### Claim 11 (depends on 1) The tubular product of claim 1, wherein the second layer is between 1 μm and 30 μm thick. ### Claim 12 (depends on 11) The tubular product of claim 11, wherein the second layer is between 5 μm and 30 μm thick. ### Claim 13 (depends on 9) The oilfield tubular of claim 9, wherein the second layer is between 1 μm and 30 μm thick. ### Claim 14 (depends on 13) The oilfield tubular of claim 13, wherein the second layer is between 5 μm and 30 μm thick. ### Claim 15 (depends on 1) The tubular product of claim 1, the third layer including a lubricant. ### Claim 16 (depends on 15) The tubular product of claim 15, the lubricant including a solid lubricant that includes one or more of graphite, polytetrafluorethylene, MoS2, or WS2. ### Claim 17 (depends on 1) The tubular product of claim 1, the third layer including a triplex coating. ### Claim 18 (depends on 1) The tubular product of claim 1, the third layer including one or more of epoxy phenolics, polyphenylene sulfide, polytetrafluorethylene, or MoS2. ### Claim 19 (depends on 4) The tubular product of claim 4, the H2S sensing material comprising CuO—SnO2 Core/Shell PN-Junction nanorods, CuO modified SnO2 nanoribbons, CuO doped SnO2 nanowires, WO3 nanoparticle, or ZnO nanorods.