MANUFACTURE

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Application No. 15/144856, filed on May 3, 2016, which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] This disclosure relates to coatings and in particular to coatings comprising carbon composite fillers and methods of manufacture.

[0003] Coatings have widespread applications in various industries. Polymer coatings have been used in downhole tools to modify surface hydrophilicity, corrosion resistance, or friction and wear resistance. Ceramic coatings are used on bearings and valves to improve wear resistance. Coatings can also be used to change surface electrical or thermal properties. Due to their broad use, there remains a need in the art for new coatings having balanced properties.

BRIEF DESCRIPTION

[0004] An article comprises a substrate, a coating disposed on a surface of the substrate, the coating comprising a carbon composite dispersed in one or more of the following: a polymer matrix; a metallic matrix; or a ceramic matrix, wherein the carbon composite comprises carbon and a binder containing one or more of the following: Si0 ₂ ; Si; B; B ₂ 0 ₃ ; a filler metal; or an alloy of the filler metal, and the filler metal comprises one or more of the following: aluminum; copper; titanium; nickel; tungsten; chromium; iron;

manganese; zirconium; hafnium; vanadium; niobium; molybdenum; tin; bismuth; antimony; lead; cadmium; or selenium.

[0005] A method of coating a substrate comprises depositing a matrix material and a carbon composite on a surface of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

[0007] FIG. 1 is a schematic illustration of an article according to an embodiment of the disclosure; and [0008] FIG. 2 illustrates an exemplary process to coat a substrate.

DETAILED DESCRIPTION

[0009] The inventors hereof have found that carbon composites formed from graphite and micro- or nano-sized binders can be used in various coatings as filler to further improve the coatings' mechanical, chemical, electrical, or thermal properties. In particular, the incorporation of carbon composites can improve the sealing performance of polymer coatings when used in certain applications. The self-lubricating property of carbon composites can improve wear resistance of the coatings. The carbon composite filler can also bring high thermal and electrical conductivity to the coatings. Moreover, carbon composites have excellent thermal and chemical stability and can improve the performance of the coatings in harsh environments.

[0010] An article according to the disclosure comprises a substrate and a coating disposed on a surface of the substrate. The coating includes a matrix and a carbon composite dispersed in the matrix. The matrix can be a polymer matrix; a metallic matrix; a ceramic matrix; or a combination comprising at least one of the foregoing. The amount of the carbon composite in the matrix can vary depending on the desired properties of the coating and the specific composition of the matrix. In an embodiment, the carbon composite is present in an amount of about 0.1 wt.% to about 75 wt.%, about 0.1 wt.% to about 50 wt.%, about 1 wt.% to about 40 wt.% or about 5 wt.% to about 30 wt.%, based on the total weight of the coating.

[0011] The polymer matrix can comprise a thermoplastic polymer, an elastomer, or a combination comprising at least one of the foregoing. The polymer matrix can comprise a blend of polymers. The polymer matrix can also comprise an oligomer, a homopolymer, a copolymer, a crosslinked polymer, or a combination comprising at least one of the foregoing.

[0012] Exemplary polymers in the polymer matrix include a polyaryletherketone, a fluoropolymer, a polyarylene sulfide such as a polyphenylene sulfide, a polyarylene such as a polyphenylene, a polyarylene sulfone such as a polyphenylsulfone, a polyether sulfone, a polyarylene ether, a polyurea, a polyurethane, a polycarbonate, a polyimide such as a polyetherimide, an ethylene-propylene-diene monomer rubber; a butadiene rubber; a styrene- butadiene rubber; a natural rubber; an acrylonitrile butadiene rubber; a styrene-butadiene- acrylonitrile resin; a butadiene-nitrile rubber; a polyisoprene rubber; an acrylate-butadiene rubber; a polychloroprene rubber; an acrylate-isoprene rubber; an ethylene-vinyl acetate rubber; a polypropylene oxide rubber; a crosslinked product thereof, or a combination comprising at least one of the foregoing. [0013] The polyaryletherketone can have a repeat unit that includes a phenylene group, ether group, ketone group, derivatives thereof, or a combination thereof. The phenyl ring of the repeat unit can be substituted in an embodiment. Exemplary polyaryletherketone polymers include polyetherketone (PEK), polyetheretherketone (PEEK),

polyetherketoneketone (PEKK), polyetheretherketoneketone (PEEKK),

polyetherketoneetherketoneketone (PEKEKK), and the like.

[0014] In an embodiment, the polymer is a fluoropolymer. Exemplary fluoropolymer polymers include polytetrafluoroethylene (PTFE, available under the trade name Teflon from DuPont), polyethylenetetrafluoroethylene (ETFE, available under the trade name Teflon ETFE or Tefzel from DuPont), fluorinated ethylene propylene copolymer (FEP, available under the trade name Teflon FEP from DuPont), perfluoroalkoxy polymer (PFA, available under the trade name Teflon PFA from DuPont), polyvinylidene fluoride (PVDF, available under the trade name Hylar from Solvay Solexis S.p.A.), polyvinylfluoride (PVF, available under the trade name Tedlar from DuPont), polychlorotrifluoroethylene (PCTFE, available under the trade name Kel-F from 3M Corp. or Neoflon from Daikin),

polyethylenechlorotrifluoroethylene (ECTFE, available under the trade name Halar ECTFE from Solvay Solexis S.p.A.), chlorotrifluoroethylenevinylidene fluoride (FKM fluorocarbon, available under the trade name Viton from FKM-Industries), perfluoroelastomer such as FFKM (available under the trade name Kalrez from DuPont), tetrafluoroethylene-propylene elastomeric copolymers such as those available under the trade name Aflas from Asahi Glass Co), perfluoropolyether (available under the trade name Krytox from DuPont),

perfluorosulfonic acid (available under the trade name Nafion from DuPont), and the like. Other exemplary fluoropolymers include copolymers of vinylidene fluoride and

hexafluoropropylene and terpolymers of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene.

[0015] In another embodiment, the polymer matrix comprises a self-reinforced polyphenylene (SRP). SRP can have a repeat unit that includes 1,3 -phenylene, benzoyl-1,4- phenylene, phenoxy-benzoyl-l,4-phenylene, derivatives thereof, or a combination thereof. The phenyl ring of the repeat unit can be substituted. As a specific example, the SRP is a copolymer of benzoyl-l,4-phenylene and 1,3-phenylene. This SRP can be made by a method described in U.S. Patent No. 5,976,437.

[0016] In a particular embodiment, the polymer is a crosslinked polyphenylene sulfide (x-PPS), crosslinked polyphenylsulfone (x-PPSU), crosslinked self-reinforced polyphenylene (x-SRP), crosslinked polyethersulfone (x-PESU), or a combination comprising at least one of the foregoing. The crosslinked product includes a crosslink between, for example, x-PPS, x-PPSU, x-SRP, x-PESU, or a combination comprising at least one of the foregoing. Descriptions of x-PPS, x-PPSU, and x-SRP and processes for making each are described in U.S. Patent Nos. 8,604, 157, 8,929, 119, 8,939,222, 9,120,898, and 9, 144,925.

[0017] The metallic matrix in the coating includes Ni, Cu, Ag, Au, Sn, Zn, Fe, In, W, Ti, Co, Al, Mg, Cr, or Mo, or alloys of these metals, or a combination that includes at least one of these materials. In an embodiment, the metallic material includes an Ni-base alloy, Ti-based alloy, or Al-based alloy, where Ni, Ti, or Al is the majority constituent element by weight or atom percent. In another embodiment, the metallic material includes an Ni-B alloy, an Ni-P alloy, or a Ni-W alloy. Exemplary Ni-B alloys contain up to about 10 percent by weight of boron, the balance being Ni and trace impurities. Exemplary Ni-P alloy contains about 14 percent or less by weight P and the balance Ni and trace impurities. An Ni- W alloy (or W-Ni alloy) includes up to about 76 percent by weight of tungsten, and more particularly up to about 30 percent by weight of tungsten. In certain embodiments, this may include about 0.1 to about 76 percent by weight of tungsten, and more particularly about 0.1 to about 30 percent by weight of tungsten. The trace impurities will be those known conventionally for Ni and Ni alloys based on the methods employed to process and refine the constituent element or elements. Exemplary aluminum-based alloys include Al-Cu alloy, Al- Mn alloy, Al-Si alloy, Al-Mg alloy, Al-Mg-Si alloy, Al-Zn alloy, Al-Li alloy, Al-Cu-Mg-X alloy, Al-Zn-Mg-Cu-X, where X represents alloying elements including Zn, Mn, Si, Cr, Fe, Ni, Ti, V, Cu, Pb, Bi, and Zr.

[0018] The ceramic matrix is not particularly limited and can be selected depending on the particular substrate used. Examples of the ceramic matrix include an oxide-based ceramic, nitride-based ceramic, carbide-based ceramic, boride-based ceramic, silicide-based ceramic, or a combination thereof. In an embodiment, the oxide-based ceramic is silica (Si0 ₂ ) or titanium dioxide (T1O ₂ ). The oxide-based ceramic, nitride-based ceramic, carbide- based ceramic, boride-based ceramic, or silicide-based ceramic can contain a nonmetal (e.g., oxygen, nitrogen, boron, carbon, or silicon, and the like), metal (e.g., aluminum, lead, bismuth, and the like), transition metal (e.g., niobium, tungsten, titanium, zirconium, hafnium, yttrium, and the like), alkali metal (e.g., lithium, potassium, and the like), alkaline earth metal (e.g., calcium, magnesium, strontium, and the like), rare earth (e.g., lanthanum, cerium, and the like), or halogen (e.g., fluorine, chlorine, and the like). [0019] The coating comprises a carbon composite, which contains carbon and an inorganic binder. The carbon can be graphite. As used herein, graphite includes one or more of natural graphite; synthetic graphite; expandable graphite; or expanded graphite. Natural graphite is graphite formed by Nature. It can be classified as "flake" graphite, "vein" graphite, and "amorphous" graphite. Synthetic graphite is a manufactured product made from carbon materials. Pyrolytic graphite is one form of the synthetic graphite. Expandable graphite refers to graphite having intercallant materials inserted between layers of natural graphite or synthetic graphite. A wide variety of chemicals have been used to intercalate graphite materials. These include acids, oxidants, halides, or the like. Exemplary intercallant materials include sulfuric acid, nitric acid, chromic acid, boric acid, S0 ₃ , or halides such as FeCl ₃ , ZnCl ₂ , and SbCl _5. Upon heating, the intercallant is converted from a liquid or solid state to a gas phase. Gas formation generates pressure which pushes adjacent carbon layers apart resulting in expanded graphite. The expanded graphite particles are vermiform in appearance, and are therefore commonly referred to as worms.

[0020] In an embodiment, the carbon composites comprise carbon microstructures having interstitial spaces among the carbon microstructures; wherein the binder is disposed in at least some of the interstitial spaces. In an embodiment, the carbon microstructures comprise unfilled voids within the carbon microstructures. In another embodiment, both the interstitial spaces among the carbon microstructures and the voids within the carbon microstructures are filled with the binder or a derivative thereof.

[0021] The carbon microstructures are microscopic structures of graphite formed after compressing graphite into highly condensed state. They comprise graphite basal planes stacked together along the compression direction. As used herein, carbon basal planes refer to substantially flat, parallel sheets or layers of carbon atoms, where each sheet or layer has a single atom thickness. The graphite basal planes are also referred to as carbon layers. The carbon microstructures are generally flat and thin. They can have different shapes and can also be referred to as micro-flakes, micro-discs and the like. In an embodiment, the carbon microstructures are substantially parallel to each other.

[0022] There are two types of voids in the carbon composites - voids or interstitial spaces among carbon microstructures and voids within each individual carbon

microstructures. The interstitial spaces among the carbon microstructures have a size of about 0.1 to about 100 microns, specifically about 1 to about 20 microns whereas the voids within the carbon microstructures are much smaller and are generally between about 20 nanometers to about 1 micron, specifically about 200 nanometers to about 1 micron. The shape of the voids or interstitial spaces is not particularly limited. As used herein, the size of the voids or interstitial spaces refers to the largest dimension of the voids or interstitial spaces and can be determined by high resolution electron or atomic force microscope technology.

[0023] The interstitial spaces among the carbon microstructures are filled with a micro- or nano-sized binder. For example, a binder can occupy about 10 % to about 90 % of the interstitial spaces among the carbon microstructures. In an embodiment, the binder does not penetrate the individual carbon microstructures and the voids within the carbon microstructures are unfilled, i.e., not filled with any binder. Thus the carbon layers within the carbon microstructures are not locked together by a binder. Through this mechanism, the flexibility of the carbon composites, particularly, expanded carbon composites can be preserved. In another embodiment, to achieve high strength, the voids within the carbon microstructures are filled with the binder or a derivative thereof. Methods to fill the voids within the carbon microstructures include vapor deposition.

[0024] The carbon microstructures have a thickness of about 1 to about 200 microns, about 1 to about 150 microns, about 1 to about 100 microns, about 1 to about 50 microns, or about 10 to about 20 microns. The diameter or largest dimension of the carbon microstructures is about 5 to about 500 microns or about 10 to about 500 microns. The aspect ratio of the carbon microstructures can be about 10 to about 500, about 20 to about 400, or about 25 to about 350. In an embodiment, the distance between the carbon layers in the carbon microstructures is about 0.3 nanometers to about 1 micron. The carbon microstructures can have a density of about 0.5 to about 3 g/cm ³ , or about 0.1 to about 2 g/cm ³ .

[0025] In the carbon composites, the carbon microstructures are held together by a binding phase. The binding phase comprises a binder which binds carbon microstructures by mechanical interlocking. Optionally, an interface layer is formed between the binder and the carbon microstructures. The interface layer can comprise chemical bonds, solid solutions, or a combination thereof. When present, the chemical bonds, solid solutions, or a combination thereof may strengthen the interlocking of the carbon microstructures. It is appreciated that the carbon microstructures may be held together by both mechanical interlocking and chemical bonding. For example the chemical bonding, solid solution, or a combination thereof may be formed between some carbon microstructures and the binder or for a particular carbon microstructure only between a portion of the carbon on the surface of the carbon microstructure and the binder. For the carbon microstructures or portions of the carbon microstructures that do not form a chemical bond, solid solution, or a combination thereof, the carbon microstructures can be bound by mechanical interlocking. The thickness of the binding phase is about 0.1 to about 100 microns or about 1 to about 20 microns. The binding phase can form a continuous or discontinuous network that binds carbon

microstructures together.

[0026] Exemplary binders include a nonmetal, a metal, an alloy, or a combination comprising at least one of the foregoing. The nonmetal is one or more of the following: Si0 ₂ ; Si; B; or B ₂ 0 . The metal can be at least one of aluminum; copper; titanium; nickel;

tungsten; chromium; iron; manganese; zirconium; hafnium; vanadium; niobium;

molybdenum; tin; bismuth; antimony; lead; cadmium; or selenium. The alloy includes one or more of the following: aluminum alloys; copper alloys; titanium alloys; nickel alloys;

tungsten alloys; chromium alloys; iron alloys; manganese alloys; zirconium alloys; hafnium alloys; vanadium alloys; niobium alloys; molybdenum alloys; tin alloys; bismuth alloys; antimony alloys; lead alloys; cadmium alloys; or selenium alloys. In an embodiment, the binder comprises one or more of the following: copper; nickel; chromium; iron; titanium; an alloy of copper; an alloy of nickel; an alloy of chromium; an alloy of iron; or an alloy of titanium. Exemplary alloys include steel, nickel-chromium based alloys such as INCONEL, and nickel-copper based alloys such as Monel alloys. Nickel-chromium based alloys can contain about 40-75% of Ni and about 10-35% of Cr. The nickel-chromium based alloys can also contain about 1 to about 15% of iron. Small amounts of Mo, Nb, Co, Mn, Cu, Al, Ti, Si, C, S, P, B, or a combination comprising at least one of the foregoing can also be included in the nickel-chromium based alloys. Nickel-copper based alloys are primarily composed of nickel (up to about 67%) and copper. The nickel-copper based alloys can also contain small amounts of iron, manganese, carbon, and silicon. These materials can be in different shapes, such as particles, fibers, and wires. Combinations of the materials can be used.

[0027] The binder used to make the carbon composites can be micro- or nano-sized. In an embodiment, the binder has an average particle size of about 0.05 to about 250 microns, about 0.05 to about 50 microns, about 1 micron to about 40 microns, specifically, about 0.5 to about 5 microns, more specifically about 0.1 to about 3 microns. Without wishing to be bound by theory, it is believed that when the binder has a size within these ranges, it disperses uniformly among the carbon microstructures.

[0028] When an interface layer is present, the binding phase comprises a binder layer comprising a binder and an interface layer bonding one of the at least two carbon microstructures to the binder layer. In an embodiment, the binding phase comprises a binder layer, a first interface layer bonding one of the carbon microstructures to the binder layer, and a second interface layer bonding the other of the microstructures to the binder layer. The first interface layer and the second interface layer can have the same or different compositions.

[0029] The interface layer comprises one or more of the following: a C-metal bond; a C-B bond; a C-Si bond; a C-O-Si bond; a C-O-metal bond; or a metal carbon solution. The bonds are formed from the carbon on the surface of the carbon microstructures and the binder.

[0030] In an embodiment, the interface layer comprises carbides of the binder. The carbides include one or more of the following: carbides of aluminum; carbides of titanium; carbides of nickel; carbides of tungsten; carbides of chromium; carbides of iron; carbides of manganese; carbides of zirconium; carbides of hafnium; carbides of vanadium; carbides of niobium; or carbides of molybdenum. These carbides are formed by reacting the

corresponding metal or metal alloy binder with the carbon atoms of the carbon

microstructures. The binding phase can also comprise SiC formed by reacting Si0 ₂ or Si with the carbon of carbon microstructures, or B ₄ C formed by reacting B or B ₂ 0 with the carbon of the carbon microstructures. When a combination of binder materials is used, the interface layer can comprise a combination of these carbides. The carbides can be salt-like carbides such as aluminum carbide, covalent carbides such as SiC and B ₄ C, interstitial carbides such as carbides of the group 4, 5, and 6 transition metals, or intermediate transition metal carbides, for example the carbides of Cr, Mn, Fe, Co, and Ni.

[0031] In another embodiment, the interface layer comprises a solid solution of carbon such as graphite and a binder. Carbon has solubility in certain metal matrix or at certain temperature ranges, which can facilitate both wetting and binding of a metal phase onto the carbon microstructures. Through heat-treatment, high solubility of carbon in metal can be maintained at low temperatures. These metals include one or more of Co; Fe; La; Mn; Ni; or Cu. The binder layer can also comprise a combination of solid solutions and carbides.

[0032] The carbon composites comprise about 20 to about 95 wt. %, about 20 to about 80 wt. %, or about 50 to about 80 wt. % of carbon, based on the total weight of the carbon composites. The binder is present in an amount of about 5 wt. % to about 75 wt. % or about 20 wt. % to about 50 wt. %, based on the total weight of the carbon composites. In the carbon composites, the weight ratio of carbon relative to the binder is about 1 :4 to about 20: 1, or about 1 :4 to about 4: 1, or about 1 : 1 to about 4: 1.

[0033] Carbon composites can be manufactured by methods described in U.S.

Publication No. 2016/0089648. [0034] The coating formed on the substrate can completely cover the substrate or a surface of the substrate. The thickness of the coating can be from about 5 μιη to about 10 mm, specifically about 10 μπι to about 5 mm. In an embodiment, the coating is continuous and does not have voids, microvoids, fractures, or other defects, including pinholes and the like.

[0035] The substrate can be a polymer, metal or ceramic material. Exemplary materials for the substrate can include those described herein for the coating matrix. In an embodiment, the substrate comprises a metal of elements from Group 2 to Group 12 of the periodic table, alloys thereof, or a combination thereof. Exemplary metals are magnesium, aluminum, titanium, manganese, iron, cobalt, nickel, copper, molybdenum, tungsten, palladium, chromium, ruthenium, gold, silver, zinc, zirconium, vanadium, silicon, or a combination thereof, including alloys thereof. Metal alloys include, for example, an aluminum-based alloy, magnesium-based alloy, tungsten-based alloy, cobalt-based alloy, iron-based alloy, nickel-based alloy, cobalt and nickel-based alloy, iron and nickel-based alloy, iron and cobalt-based alloy, copper-based alloy, and titanium-based alloy. As used herein, the term "metal-based alloy" means a metal alloy wherein the weight percentage of the specified metal in the alloy is greater than the weight percentage of any other component of the alloy, based on the total weight of the alloy. Exemplary metal alloys include steel, nichrome, brass, pewter, bronze, invar, inconel, hastelloy, MgZrZn, MgAlZn, AlCuZnMn, and AlMgZnSiMn.

[0036] In an embodiment, the substrate comprises one or more of the following: copper; nickel; chromium; iron; titanium; an alloy of copper; an alloy of nickel; an alloy of chromium; an alloy of iron; or an alloy of titanium. Exemplary alloys include steel, nickel- chromium based alloys such as INCONEL, and nickel-copper based alloys such as Monel alloys. Nickel-chromium based alloys can contain about 40-75% of Ni and about 10-35% of Cr. The nickel-chromium based alloys can also contain about 1 to about 15% of iron. Small amounts of Mo, Nb, Co, Mn, Cu, Al, Ti, Si, C, S, P, B, or a combination comprising at least one of the foregoing can also be included in the nickel-chromium based alloys. Nickel- copper based alloys are primarily composed of nickel (up to about 67%) and copper. The nickel-copper based alloys can also contain small amounts of iron, manganese, carbon, and silicon. A reinforcing agent known in the art can be included in the substrate if desired.

[0037] The substrate can be used without surface processing or can be processed, including chemically, physically, or mechanically treating the substrate. For example, the substrate can be treated to roughen or increase a surface area of the substrate, e.g., by sanding, lapping, or sand blasting. A surface of the substrate can also be cleaned to remove contaminants through chemical and/or mechanical means.

[0038] The substrate can be any shape. Exemplary shapes include a cube, sphere, cylinder, toroid, polygonal shape, helix, truncated shape thereof, or a combination thereof. The longest linear dimension of the substrate can be from 500 nm to hundreds of meters, without limitation. The substrate can have a thermal decomposition temperature that can withstand, without decomposition or degradation, exposure to a temperature from -10°C to 800°C. However, coating disposed on the substrate can provide temperature shielding or thermal conductance to carry heat away from the substrate so that the substrate does not experience a temperature near its thermal decomposition temperature.

[0039] Optionally, the coating is bound to the substrate through a binding layer. The thickness of the binding layer can be about 50 nm to about 2 mm or about 100 nm to about 1 mm. The binding layer can comprise a primer, metals, alloys thereof, or solid solutions of metals. Other known inorganic or organic binders can also be used.

[0040] FIG. 1 is a schematic illustration of an article according to an embodiment of the disclosure. As shown in FIG. 1, the article comprises substrate 2 and coating 1 disposed on a surface of substrate 1. The coating 1 comprises matrix 4 and carbon composite 3 disposed in matrix 4.

[0041] Methods of forming a coating comprises combining a carbon composite with a matrix material to provide a coating composition; and disposing the coating composition on a surface of a substrate to form the coating.

[0042] The carbon composite can be in different forms such as powders, fibers, pellets, or the like. The powder comprises particles having an average size of about 1 μπι to about 1 cm. The pellets comprise particles having an average size of about 500 microns to about 5 cm. In an embodiment, the density and the size of the carbon composites are selected in such a way that the carbon composites are uniformly dispersed in the matrix material. In an embodiment, to facilitate uniform distribution of the carbon composite in the matrix material, the carbon composite is in the form of a powder. To ensure uniform dispersion, mixing, blending, or other known method can be used.

[0043] The matrix material can be the material in the polymer matrix.

Alternatively, the matrix material in the coating composition is a precursor of the material in the polymer matrix. For example, the matrix material in the coating composition is an uncrosslinked polymer, which is crosslinked while the coating composition is applied to a surface of a substrate or after the coating composition is disposed on a surface of the substrate. A known crosslinking agent can be included in the coating composition. As another specific example, the matrix material in the coating composition comprises one or more monomers or oligomers, which can be polymerized or cured later forming a coating comprising polymerized or cured matrix material. The matrix material can also include at least one metal or metal alloy which is sintered forming the metallic matrix.

[0044] The coating composition can be in the form of a powder, a dispersion, a paste, a solution, or an emulsion. When the matrix material is a material or a precursor for a polymer matrix, the matrix material can be dispersed or dissolved in a solvent forming a slurry or a solution. For this embodiment, combining the carbon composite with the matrix material includes dispersing the carbon composite in the slurry or the solution comprising the matrix material. Surfactants and dispersing agents can be included in the slurry or solution to facilitate uniform dispersion of the carbon composite and the matrix material. When the matrix material is a material or a precursor for a metallic or ceramic matrix, the matrix material can be combined with the carbon composite and organics forming a paste.

[0045] A coating composition comprising a matrix material for a polymer matrix and a carbon composite can be disposed on a surface of a substrate by known methods such as spray coating, brushing, screen casting, blade casting, drop casting, spin coating, molding, and the like. In the instance where the matrix material in the coating composition is a precursor of the material in the polymer matrix, the coated composition can be further treated to polymerize, cure, or crosslink the matrix material.

[0046] A coating composition such as a paste comprising a matrix material for a metallic or ceramic matrix and a carbon composite can be disposed on a surface of a substrate by brushing, immersion dipping, or molding. If desired, the coated composition can be sintered to form a dense coating layer and/or to form a bonding layer between the coating and the substrate. Methods of sintering are not particularly limited and include hot pressing, spark plasma sintering, and the like.

[0047] In some embodiments, the matrix material and the carbon composite are deposited on a surface of a substrate simultaneously. An exemplary method includes thermal spray coating where a metal or ceramic melt flow and a carbon composite flow optionally carried by a gas are sprayed onto a target substrate simultaneously.

[0048] In other embodiments, the mixture of matrix material and the carbon composite is deposited on a surface of a substrate by all-solid state coating processes. An exemplary method includes cold gas-dynamic spray (or simply cold spray) that is a process of applying coatings by exposing a metallic or dielectric substrate to a high velocity (300-1200 m/s) jet of particles accelerated by a supersonic jet of compressed gas at a temperature that is always lower than the melting point of the material, resulting in a coating on a substrate from particles in the solid state.

[0049] Electroplating can also be used to form a coating comprising a carbon composite and a metallic matrix. In the method, the carbon composite is combined with a precursor for the metallic matrix, and both the carbon composite and the metallic matrix are deposited on a surface of a substrate under an electric field. Illustratively, a coating comprising Ni as metallic matrix material may be deposited using a nickel sulfate bath containing a carbon composite. In another exemplary embodiment, a coating comprising an Ni-P alloy as metallic matrix may be deposited by an electrochemical deposition using a bath that includes nickel sulfate, sodium hypophosphite, and a carbon composite. A coating comprising an Ni-W alloy as metallic matrix may be deposited by an electrochemical deposition using a bath that includes nickel sulfate and sodium tungstate.

[0050] An exemplary method is illustrated in FIG. 2. As shown in FIG. 2, bulk carbon composite 10 is milled into a carbon composite powder 11, which is combined with a matrix material 14 forming a coating composition 12. The coating composition is disposed on a surface of a substrate 15 forming a coated substrate 18. The coating 16 comprises carbon composite 11 disposed in matrix 17.

[0051] If needed, a binding layer can be formed between the coating and the substrate. The binding layer can be formed from a primer layer coating on the substrate. Alternatively, the binding layer can be formed in situ by heating the coating and the coated surface. A pressure may be applied during the heating.

[0052] Articles containing coatings as disclosed herein are useful for a wide variety of applications including but are not limited to electronics, atomic energy, hot metal processing, coatings, aerospace, automotive, oil and gas, and marine applications. Exemplary articles include coated bearings; coated valves such as safety valves; coated pipelines, for example, those used in chemical plants; coated pistons, and coated shafts. Coated bearings can be used in downhole tools such as ESP pump, drilling bit, or the like or in pharmacy or food industry where oil lubricants are prohibited for safety concerns. Coated pistons and coated shafts can be used in various machine or tool parts including engines and gears, and the like for applications in the oil and gas industry, automobile industry, or aerospace industry.

[0053] Set forth below are various embodiments of the disclosure. [0054] Embodiment 1. An article comprising a substrate, a coating disposed on a surface of the substrate, the coating comprising a carbon composite dispersed in one or more of the following: a polymer matrix; a metallic matrix; or a ceramic matrix, wherein the carbon composite comprises carbon and a binder containing one or more of the following: Si0 ₂ ; Si; B; B ₂ 0 ; a filler metal; or an alloy of the filler metal, and the filler metal comprises one or more of the following: aluminum; copper; titanium; nickel; tungsten; chromium; iron; manganese; zirconium; hafnium; vanadium; niobium; molybdenum; tin; bismuth; antimony; lead; cadmium; or selenium.

[0055] Embodiment 2. The article of Embodiment 1, wherein the carbon composite is present in an amount of about 0.1 wt.% to about 75 wt.% based on the total weight of the coating.

[0056] Embodiment 3. The article of Embodiment 1 or Embodiment 2, wherein the coating has a thickness of about 5μπι to about 10 mm.

[0057] Embodiment 4. The article of any one of Embodiments 1 to 3, wherein the carbon composite comprises at least two carbon microstructures; and a binding phase disposed between the at least two carbon microstructures.

[0058] Embodiment 5. The article of Embodiment 4, wherein the binding phase comprises a binder layer and an interface layer bonding one of the at least two carbon microstructures to the binder layer, wherein the interface layer comprises one or more of the following: a C-metal bond; a C-B bond; a C-Si bond; a C-O-Si bond; a C-O-metal bond; or a metal carbon solution.

[0059] Embodiment 6. The article of any one of Embodiments 1 to 5, wherein the carbon comprises graphite.

[0060] Embodiment 7. The article of any one of Embodiments 1 to 6, wherein the coating comprises a metallic matrix including one or more of the following: Ni; Cu; Ag; Au; Sn; Zn; Fe; In; W; Ti; Co; Al; Mg; Cr; or Mo; or an alloy thereof.

[0061] Embodiment 8. The article of any one of Embodiments 1 to 6, wherein the coating comprises a ceramic matrix comprising one or more of the following: an oxide-based ceramic; nitride-based ceramic; carbide-based ceramic; boride-based ceramic; or silicide- based ceramic.

[0062] Embodiment 9. The article of any one of Embodiments 1 to 6, wherein the polymer matrix comprises a thermoplastic polymer, an elastomer, or a combination thereof.

[0063] Embodiment 10. The article of any one of Embodiments 1 to 9, further comprising a binding layer disposed between the coating and the substrate. [0064] Embodiment 11. The article of any one of Embodiments 1 to 10, wherein the substrate comprises one or more of the following: a metal; a polymer; or ceramics.

[0065] Embodiment 12. The article of any one of Embodiments 1 to 1 1, wherein the article is a coated bearing, a coated pipeline, a coated valve, a coated piston, or a coated shaft.

[0066] Embodiment 13. A method of coating a substrate, the method comprising: depositing a matrix material and a carbon composite on a surface of a substrate, the carbon composite comprising carbon and a binder; the binder comprising one or more of the following: Si0 ₂ ; Si; B; B ₂ 0 ; a metal; or an alloy of the metal; and the metal comprising one or more of the following: aluminum; copper; titanium; nickel; tungsten; chromium; iron; manganese; zirconium; hafnium; vanadium; niobium; molybdenum; tin; bismuth; antimony; lead; cadmium; or selenium.

[0067] Embodiment 14. The method of Embodiment 13, further comprising combining a matrix material with a carbon composite to form a coating composition.

[0068] Embodiment 15. The method of Embodiment 14, wherein depositing a matrix material and a carbon composite comprises disposing the coating composition on a surface of the substrate.

[0069] Embodiment 16. The method of Embodiment 15, wherein the matrix material comprises a material or a precursor for the polymer matrix, and combing the matrix material with the carbon composite comprises dispersing the carbon composite in a dispersion of the matrix material.

[0070] Embodiment 17. The method of Embodiment 16, wherein disposing the coating composition comprises one or more of the following: spray coating; brushing; screen casting; blade casting; drop casting; spin coating; or molding.

[0071] Embodiment 18. The method of Embodiment 15, wherein the matrix material comprises a material or a precursor for the metallic or ceramic matrix, and the matrix material is combined with a carbon composite and an organic compound to form a coating composition in the form of a paste.

[0072] Embodiment 19. The method of Embodiment 18, wherein disposing the coating composition comprises brushing, immersion dipping, or molding.

[0073] Embodiment 20. The method of Embodiment 13, wherein disposing the matrix material and the carbon composite is an all-solid state coating process.

[0074] Embodiment 21. The method of Embodiment 14, wherein disposing the matrix material and the carbon composite comprises thermal spraying the matrix material and the carbon composite simultaneously on the surface of the substrate. [0075] Embodiment 22. The method of Embodiment 14, wherein the coating comprises a metallic matrix, and depositing the matrix material and the carbon composite is conducted via electroplating.

[0076] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. The suffix "(s)" as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including at least one of that term (e.g., the colorant(s) includes at least one colorants). "Or" means "and/or." "Optional" or "optionally" means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. As used herein, "combination" is inclusive of blends, mixtures, alloys, reaction products, and the like. "A combination thereof means "a combination comprising one or more of the listed items and optionally a like item not listed." All references are incorporated herein by reference.

[0077] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should further be noted that the terms "first," "second," and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The modifier "about" used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity).

[0078] While typical embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed to be a limitation on the scope herein. Accordingly, various modifications, adaptations, and alternatives can occur to one skilled in the art without departing from the spirit and scope herein.