Carbon composites

Information

  • Patent Grant
  • 10202310
  • Patent Number
    10,202,310
  • Date Filed
    Thursday, March 3, 2016
    8 years ago
  • Date Issued
    Tuesday, February 12, 2019
    5 years ago
  • Inventors
  • Original Assignees
    • BAKER HUGHES, A GE COMPANY, LLC (Houston, TX, US)
  • Examiners
    • Park; Lisa S
    Agents
    • Cantor Colburn LLP
Abstract
A carbon composite comprises: at least two carbon microstructures; and a binding phase disposed between the at least two carbon microstructures; wherein the binding phase includes a binder comprising one or more of the following SiO2; Si; B; B2O3; a metal; or an alloy of the metal, and the metal is at least one of aluminum; copper; titanium; nickel; tungsten; chromium; iron; manganese; zirconium; hafnium; vanadium; niobium; molybdenum; tin; bismuth; antimony; lead; cadmium; or selenium.
Description
BACKGROUND

Graphite is an allotrope of carbon and has a layered, planar structure. In each layer, the carbon atoms are arranged in hexagonal arrays or networks through covalent bonds. Different carbon layers however are held together only by weak van der Waals forces.


Graphite has been used in a variety of applications including electronics, atomic energy, hot metal processing, coatings, aerospace and the like due to its excellent thermal and electrical conductivities, lightness, low friction, and high heat and corrosion resistances. However, graphite is not elastic and has low strength, which may limit its further applications. Thus, the industry is always receptive to new graphite materials having improved elasticity and mechanical strength. It would be a further advantage if such materials also have improved high temperature corrosion resistance.


BRIEF DESCRIPTION

The above and other deficiencies in the prior art are be overcome by, in an embodiment, a carbon composite comprising carbon microstructures having interstitial spaces among the carbon microstructures; and a binder disposed in at least some of the interstitial spaces; wherein the carbon microstructures comprises unfilled voids within the carbon microstructures.


In another embodiment, a carbon composite comprises: at least two carbon microstructures; and a binding phase disposed between the at least two carbon microstructures; wherein the binding phase includes a binder comprising SiO2, Si, B, B2O3, a metal, an alloy of the metal, or a combination comprising at least one of the foregoing; wherein the metal is at least one of aluminum, copper, titanium, nickel, tungsten, chromium, iron, manganese, zirconium, hafnium, vanadium, niobium, molybdenum, tin, bismuth, antimony, lead, cadmium, and selenium.


The composites can be in the form of a bar, block, sheet, tubular, cylindrical billet, toroid, powder, or pellets.





BRIEF DESCRIPTION OF THE DRAWINGS

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



FIG. 1 is a scanning electron microscopic (“SEM”) image of a composition containing expanded graphite and a micro- or nano-sized binder blended at room temperature and atmospheric pressure;



FIG. 2 is a SEM image of a carbon composite formed from expanded graphite and a micro- or nano-sized binder under high pressure and high temperature conditions according to one embodiment of the disclosure;



FIG. 3 is a SEM image of carbon microstructures according to another embodiment of the disclosure;



FIG. 4 is a schematic illustration of a carbon composite according to an embodiment of the disclosure;



FIG. 5 shows stress-strain curves of (A) natural graphite; (B) expanded graphite; (C) a mixture of expanded graphite and a micro- or nano-sized binder, where the sample is compacted at room temperature and high pressure; (D) a carbon composite according to one embodiment of the disclosure compacted from a mixture of expanded graphite and a micro- or nano-sized binder at a high temperature and a low pressure (also referred to as “soft composite”); and (E) a carbon composite according to another embodiment of the disclosure formed from expanded graphite and a micro- and nano-sized binder under high pressure and high temperature conditions (also referred to as “hard composite”);



FIG. 6 shows loop test results of a carbon composite at different loadings;



FIG. 7 shows hysteresis results of a carbon composite tested at room temperature and 500° F. respectively;



FIG. 8 compares a carbon composite before and after exposing to air at 500° C. for 25 hours;



FIG. 9(A) is a photo of a carbon composite after a thermal shock; FIG. 9(B) illustrates the condition for the thermal shock;



FIG. 10 compares a carbon composite sample (A) before and (B) after exposing to tap water for 20 hours at 200° F., or (C) after exposing to tap water for 3 days at 200° F.;



FIG. 11 compares a carbon composite sample (A) before and (B) after exposing to 15% HCl solution with inhibitor at 200° F. for 20 hours, or (C) after exposing to 15% HCl solution at 200° F. for 3 days; and



FIG. 12 shows the sealing force relaxation test results of a carbon composite at 600° F.





DETAILED DESCRIPTION

The inventors hereof have found that carbon composites formed from graphite and micro- or nano-sized binders at high temperatures have improved balanced properties as compared to graphite alone, a composition formed from the same graphite but different binders, or a mixture of the same graphite and the same binder blended at room temperature under atmospheric pressure or high pressures. The new carbon composites have excellent elasticity. In addition, the carbon composites have excellent mechanical strength, heat resistance, and chemical resistance at high temperatures. In a further advantageous feature, the composites keep various superior properties of the graphite such as heat conductivity, electrical conductivity, lubricity, and the alike.


Without wishing to be bound by theory, it is believed that the improvement in mechanical strength is provided by a binding phase disposed between carbon microstructures. There are either no forces or only weak Van der Waals forces exist between the carbon microstructures, thus the graphite bulk materials have weak mechanical strength. At high temperatures, the micro- and nano-sized binder liquefies and is dispersed evenly among carbon microstructures. Upon cooling, the binder solidifies and forms a binding phase binding the carbon nanostructures together through mechanical interlocking.


Further without wishing to be bound by theory, for the composites having both improved mechanical strength and improved elasticity, it is believed that the carbon microstructures themselves are laminar structures having spaces between the stacked layers. The binder only selectively locks the microstructures at their boundaries without penetrating the microstructures. Thus the unbounded layers within the microstructures provide elasticity and the binding phase disposed between the carbon microstructures provides mechanical strength.


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.


There are two types of voids in the carbon composites—voids or interstitial spaces between carbon microstructures and voids within each individual carbon microstructures. The interstitial spaces between 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.


The interstitial spaces between 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 between the carbon microstructures. However, the binder does not penetrate the individual carbon microstructures and the voids within 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 composite, particularly, expanded carbon composite can be preserved.


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/cm3, or about 0.1 to about 2 g/cm3.


As used herein, graphite includes natural graphite, synthetic graphite, expandable graphite, expanded graphite, or a combination comprising at least one of the foregoing. 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, SO3, or halides such as FeCl3, ZnCl2, and SbCl5. 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.


Advantageously, the carbon composites comprise expanded graphite microstructures. Compared with other forms of the graphite, expanded graphite has high flexibility and compression recovery, and larger anisotropy. The composites formed from expanded graphite and micro- or nano-sized binder under high pressure and high temperature conditions can thus have excellent elasticity in addition to desirable mechanical strength.


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 bounded 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.


Exemplary binders include SiO2, Si, B, B2O3, a metal, an alloy, or a combination comprising at least one of the foregoing. The metal can be aluminum, copper, titanium, nickel, tungsten, chromium, iron, manganese, zirconium, hafnium, vanadium, niobium, molybdenum, tin, bismuth, antimony, lead, cadmium, and selenium. The alloy includes the alloys of aluminum, copper, titanium, nickel, tungsten, chromium, iron, manganese, zirconium, hafnium, vanadium, niobium, molybdenum, tin, bismuth, antimony, lead, cadmium, and selenium. In an embodiment, the binder comprises copper, nickel, chromium, iron, titanium, an alloy of copper, an alloy of nickel, an alloy of chromium, an alloy of iron, an alloy of titanium, or a combination comprising at least one of the foregoing metal or metal alloy. 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, 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.


The binder used to make the carbon composite is micro- or nano-sized. In an embodiment, the binder has an average particle size of about 0.05 to about 10 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.


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.


The interface layer comprises a C-metal bond, a C—B bond, a C—Si bond, a C—O—Si bond, a C—O-metal bond, a metal carbon solution, or a combination comprising at least one of the foregoing. The bonds are formed from the carbon on the surface of the carbon microstructures and the binder.


In an embodiment, the interface layer comprises carbides of the binder. The carbides include carbides of aluminum, titanium, nickel, tungsten, chromium, iron, manganese, zirconium, hafnium, vanadium, niobium, molybdenum, or a combination comprising at least one of the foregoing. 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 SiO2 or Si with the carbon of carbon microstructures, or B4C formed by reacting B or B2O3 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, B4C, interstitial carbides such as carbides of the group 4, 5, and 5 transition metals, or intermediate transition metal carbides, for example the carbides of Cr, Mn, Fe, Co, and Ni.


In another embodiment, the interface layer comprises a solid solution of carbon and the binder. Carbon have solubility in certain metal matrix or at certain temperature range, which helps both wetting and binding of metal phase onto carbon microstructures. Through heat-treatment, high solubility of carbon in metal can be maintained at low temperature. These metals include Co, Fe, La, Mn, Ni, or Cu. The binder layer can also comprises a combination of solid solutions and carbides.


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 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 composites. In the carbon composites, the weight ratio of carbon relative to the binding is about 1:4 to about 20:1, or about 1:4 to about 4:1, or about 1:1 to about 4:1.



FIG. 1 is a SEM image of a composition containing expanded graphite and a micro- or nano-sized binder blended at room temperature and atmospheric pressure. As shown in FIG. 1, the binder (white area) is only deposited on the surface of some of the expanded graphite worms.



FIG. 2 is a SEM image of a carbon composite formed from expanded graphite and a micro- or nano-sized binder under high pressure and high temperature conditions. As shown in FIG. 2, a binding phase (light area) is evenly distributed between the expanded graphite microstructures (dark area).


A SEM image of carbon graphite microstructures are shown in FIG. 3. An embodiment of a carbon composite is illustrated in FIG. 4. As shown in FIG. 4, the composite comprises carbon microstructures 1 and binding phase 2 locking the carbon microstructures. The binding phase 2 comprises binder layer 3 and an optional interface layer 4 disposed between the binder layer and the carbon microstructures. The carbon composite contains interstitial space 5 among carbon microstructures 1. Within carbon microstructures, there are unfilled voids 6.


The carbon composites can optionally comprise a filler. Exemplary filler includes carbon fibers, carbon black, mica, clay, glass fiber, ceramic fibers, and ceramic hollow structures. Ceramic materials include SiC, Si3N4, SiO2, BN, and the like. The filler can be present in an amount of about 0.5 to about 10 wt. % or about 1 to about 8%.


The composites can have any desired shape including a bar, block, sheet, tubular, cylindrical billet, toroid, powder, pellets, or other form that may be machined, formed or otherwise used to form useful articles of manufacture. The sizes or the dimension of these forms are not particularly limited. Illustratively, the sheet has a thickness of about 10 μm to about 10 cm and a width of about 10 mm to about 2 m. The powder comprises particles having an average size of about 10 μm to about 1 cm. The pellets comprise particles having an average size of about 1 cm to about 5 cm.


One way to form the carbon composites is to compress a combination comprising carbon and a micro- or nano-sized binder to provide a green compact by cold pressing; and to compressing and heating the green compact thereby forming the carbon composites. In another embodiment, the combination can be pressed at room temperature to form a compact, and then the compact is heated at atmospheric pressure to form the carbon composite. These processes can be referred to as two-step processes. Alternatively, a combination comprising carbon and a micro- or nano-sized binder can be compressed and heated directly to form the carbon composites. The process can be referred to as a one-step process.


In the combination, the carbon such as graphite is present in an amount of about 20 wt. % to about 95 wt. %, about 20 wt. % to about 80 wt. %, or about 50 wt. % to about 80 wt. %, based on the total weight of the combination. 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 combination. The graphite in the combination can be in the form of chip, powder, platelet, flake, or the like. In an embodiment, the graphite is in the form of flakes having a diameter of about 50 microns to about 5,000 microns, preferably about 100 to about 300 microns. The graphite flakes can have a thickness of about 1 to about 5 microns. The density of the combination is about 0.01 to about 0.05 g/cm3, about 0.01 to about 0.04 g/cm3, about 0.01 to about 0.03 g/cm3 or about 0.026 g/cm3. The combination can be formed by blending the graphite and the micro- or nano-sized binder via any suitable methods known in the art. Examples of suitable methods include ball mixing, acoustic mixing, ribbon blending, vertical screw mixing, and V-blending.


Referring to the two-step process, cold pressing means that the combination comprising the graphite and the micro-sized or nano-sized binder is compressed at room temperature or at an elevated temperature as long as the binder does not significantly bond with the graphite microstructures. In an embodiment, greater than about 80 wt. %, greater than about 85 wt. %, greater than about 90 wt. %, greater than about 95 wt. %, or greater than about 99 wt. % of the microstructures are not bonded in the green compact. The pressure to form the green compact can be about 500 psi to about 10 ksi and the temperature can be about 20° C. to about 200° C. The reduction ratio at this stage, i.e., the volume of the green compact relative to the volume of the combination, is about 40% to about 80%. The density of the green compact is about 0.1 to about 5 g/cm3, about 0.5 to about 3 g/cm3, or about 0.5 to about 2 g/cm3.


The green compact can be heated at a temperature of about 350° C. to about 1200° C., specifically about 800° C. to about 1200° C. to form the carbon composites. In an embodiment, the temperature is above the melting point of the binder, for example, about 20° C. to about 100° C. higher or about 20° C. to about 50° C. higher than the melting point of the binder. When the temperature is higher, the binder becomes less viscose and flows better, and less pressure may be required in order for the binder to be evenly distributed in the voids between the carbon microstructures. However, if the temperature is too high, it may have detrimental effects to the instrument.


The temperature can be applied according to a predetermined temperature schedule or ramp rate. The means of heating is not particularly limited. Exemplary heating methods include direct current (DC) heating, induction heating, microwave heating, and spark plasma sintering (SPS). In an embodiment, the heating is conducted via DC heating. For example, the combination comprising the graphite and the micro- or nano-sized binder can be charged with a current, which flows through the combination generating heat very quickly. Optionally, the heating can also be conducted under an inert atmosphere, for example, under argon or nitrogen. In an embodiment, the green compact is heated in the presence of air.


The heating can be conducted at a pressure of about 500 psi to about 30,000 psi or about 1000 psi to about 5000 psi. The pressure can be a superatmospheric pressure or a subatmospheric pressure. Without wishing to be bound by theory, it is believed that when a superatmospheric pressure is applied to the combination, the micro- or nano-sized binder is forced into the voids between carbon microstructures through infiltration. When a subatmospheric pressure is applied to the combination, the micro- or nano-sized binder can also be forced into the voids between the carbon microstructures by capillary forces.


In an embodiment, the desirable pressure to form the carbon composites is not applied all at once. After the green compact is loaded, a low pressure is initially applied to the composition at room temperature or at a low temperature to close the large pores in the composition. Otherwise, the melted binder may flow to the surface of the die. Once the temperature reaches the predetermined maximum temperature, the desirable pressure required to make the carbon composites can be applied. The temperature and the pressure can be held at the predetermined maximum temperature and the predetermined maximum temperature for 5 minutes to 120 minutes.


The reduction ratio at this stage, i.e. the volume of the carbon composite relative to the volume of the green compact, is about 10% to about 70% or about 20 to about 40%. The density of the carbon composite can be varied by controlling the degree of compression. The carbon composites have a density of about 0.5 to about 10 g/cm3, about 1 to about 8 g/cm3, about 1 to about 6 g/cm3, about 2 to about 5 g/cm3, about 3 to about 5 g/cm3, or about 2 to about 4 g/cm3.


Alternatively, also referring to a two-step process, the combination can be first pressed at room temperature and a pressure of about 500 psi to 30,000 psi to form a compact; the compact can be further heated at a temperature higher than the melting point of the binder to make the carbon composite. In an embodiment, the temperature can be about 20° C. to about 100° C. higher or about 20° C. to about 50° C. higher than the melting point of the binder. The heating can be conducted at atmospheric pressure.


In another embodiment, the carbon composite can be made from the combination of the graphite and the binder directly without making the green compact. The pressing and the heating can be carried out simultaneously. Suitable pressures and temperatures can be the same as discussed herein for the second step of the two-step process.


Hot pressing is a process that applies temperature and pressure simultaneously. It can be used in both the one-step and the two-step processes to make carbon composites.


The carbon composites can be made in a mold through a one-step or a two-step process. The obtained carbon composites can be further machined or shaped to form a bar, block, tubular, cylindrical billet, or toroid. Machining includes cutting, sawing, ablating, milling, facing, lathing, boring, and the like using, for example, a miller, saw, lathe, router, electric discharge machine, and the like. Alternatively, the carbon composite can be directly molded to the useful shape by choosing the molds having the desired shape.


Sheet materials such as web, paper, strip, tape, foil, mat or the like can also be made via hot rolling. In an embodiment, the carbon composite sheets made by hot rolling can be further heated to allow the binder to effectively bond the carbon microstructures together.


Carbon composite pellets can be made by extrusion. For example, a combination of the graphite and the micro- or nano-sized binder can be first loaded in a container. Then combination is pushed into an extruder through a piston. The extrusion temperature can be about 350° C. to about 1200° C. or about 800° C. to about 1200° C. In an embodiment, the extrusion temperature is higher than the melting point of the binder, for example, about 20 to about 50° C. higher than the melting point of the binder. In an embodiment, wires are obtained from the extrusion, which can be cut to form pellets. In another embodiment, pellets are directly obtained from the extruder. Optionally, a post treatment process can be applied to the pellets. For example, the pellets can be heated in a furnace above the melting temperature of the binder so that the binder can bond the carbon microstructures together if the carbon microstructures have not been bonded or not adequately bonded during the extrusion.


Carbon composite powder can be made by milling carbon composites, for example a solid piece, through shearing forces (cutting forces). It is noted that the carbon composites should not be smashed. Otherwise, the voids within the carbon microstructures may be destroyed thus the carbon composites lose elasticity.


The carbon composites have a number of advantageous properties for use in a wide variety of applications. In an especially advantageous feature, by forming carbon composites, both the mechanical strength and the elastomeric properties are improved.


To illustrate the improvement of elastic energy achieved by the carbon composites, the stress-strain curves for the following samples are shown in FIG. 5: (A) natural graphite, (B) expanded graphite, (C) a mixture of expanded graphite and a micro- or nano-sized binder formed at room temperature and atmospheric pressure, (D) a mixture of expanded graphite and a micro- or nano-sized binder formed by at a high temperature and atmospheric pressure; and (E) a carbon composite formed from expanded graphite and a micro- and nano-sized binder under high pressure and high temperature conditions. For the natural graphite, the sample was made by compressing natural graphite in a steel die at a high pressure. The expanded graphite sample was also made in a similar manner.


As shown in FIG. 5, the natural graphite has a very low elastic energy (area under the stress-strain curve) and is very brittle. The elastic energy of expanded graphite and the elastic energy of the mixture of expanded graphite and a micro- or nano-sized binder compacted at room temperature and high pressure is higher than that of the natural graphite. Conversely, both the hard and soft carbon composites of the disclosure exhibit significantly improved elasticity shown by the notable increase of the elastic energy as compared to the natural graphite alone, the expanded graphite alone, and the mixture of expanded graphite and binder compacted at room temperature and high pressure. In an embodiment, the carbon composites have an elastic elongation of greater than about 4%, greater than about 6%, or between about 4% and about 40%.


The elasticity of the carbon composites is further illustrated in FIGS. 6 and 7. FIG. 6 shows loop test results of a carbon composite at different loadings. FIG. 7 shows hysteresis results of a carbon composite tested at room temperature and 500° F. respectively. As shown in FIG. 7, the elasticity of the carbon composite is maintained at 500° F.


In addition to mechanical strength and elasticity, the carbon composites can also have excellent thermal stability at high temperatures. FIG. 8 compares a carbon composite before and after exposing to air at 500° C. for 25 hours. FIG. 9(A) is a photo of a carbon composite sample after a thermo shock for 8 hours. The condition for the thermal shock is shown in FIG. 9(B). As shown in FIGS. 8 and 9(A), there are no changes to the carbon composite sample after exposing to air at 500° C. for 25 hours or after the thermal shock. The carbon composites can have high thermal resistance with a range of operation temperatures from about −65° F. up to about 1200° F., specifically up to about 1100° F., and more specifically about 1000° F.


The carbon composites can also have excellent chemical resistance at elevated temperatures. In an embodiment, the composite is chemically resistant to water, oil, brines, and acids with resistance rating from good to excellent. In an embodiment, the carbon composites can be used continuously at high temperatures and high pressures, for example, about 68° F. to about 1200° F., or about 68° F. to about 1000° F., or about 68° F. to about 750° F. under wet conditions, including basic and acidic conditions. Thus, the carbon composites resist swelling and degradation of properties when exposed to chemical agents (e.g., water, brine, hydrocarbons, acids such as HCl, solvents such as toluene, etc.), even at elevated temperatures of up to 200° F., and at elevated pressures (greater than atmospheric pressure) for prolonged periods. The chemical resistance of the carbon composite is illustrated in FIGS. 10 and 11. FIG. 10 compares a carbon composite sample before and after exposing to tap water for 20 hours at 200° F., or after exposing to tap water for 3 days at 200° F. As shown in FIG. 10, there are no changes to the sample. FIG. 11 compares a carbon composite sample before and after exposing to 15% HCl solution with inhibitor at 200° F. for 20 hours, or after exposing to 15% HCl solution at 200° F. for 3 days. Again, there are no changes to the carbon composite sample.


The carbon composites are medium hard to extra hard with harness from about 50 in SHORE A up to about 75 in SHORE D scale.


As a further advantageous feature, the carbon composites have stable sealing force at high temperatures. The stress decay of components under constant compressive strain is known as compression stress relaxation. A compression stress relaxation test also known as sealing force relaxation test measures the sealing force exerted by a seal or O-ring under compression between two plates. It provides definitive information for the prediction of the service life of materials by measuring the sealing force decay of a sample as a function of time, temperature and environment. FIG. 12 shows the sealing force relaxation test results of a carbon composite sample 600° F. As shown in FIG. 12, the sealing force of the carbon composite is stable at high temperatures. In an embodiment, the sealing force of a sample of the composite at 15% strain and 600° F. is maintained at about 5800 psi without relaxation for at least 20 minutes.


The carbon composites are useful for preparing articles 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 seals, bearings, bearing seats, packers, valves, engines, reactors, cooling systems, and heat sinks. Thus, in an embodiment, an article comprises the carbon composites. The carbon composites may be used to form all or a portion of an article.


The article can be a downhole element. Illustrative articles include seals, seal bore protector, swabbing element protector, components of frac plug, bridge plug, compression packing elements (premier seal), expanding packing elements (ARC seal), O-rings, bonded seals, bullet seals, subsurface safety valve (SSSV) dynamic seals, SSSV flapper seals, V rings, back up rings, drill bit seals, or ESP seals. In an embodiment, the article is a packer, a seal, or an O-ring.


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. All references are incorporated herein by reference.


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).


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.

Claims
  • 1. A carbon composite comprising: at least two carbon microstructures, the carbon microstructures having basal planes stacked together, and the carbon microstructures having an aspect ratio of about 10 to about 500 and being substantially parallel to each other; anda binding phase disposed between the at least two carbon microstructures;the binding phase including a binder comprising one or more of the following: SiO2; Si; B; B2O3; a metal; or an alloy of the metal; wherein the metal is at least one of aluminum; copper; titanium; nickel; tungsten; chromium; iron; manganese; zirconium; hafnium; vanadium; niobium; molybdenum; tin; bismuth; antimony; lead; cadmium, or selenium,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, and the interface layer comprises one or more of the following: a C—O-metal bond; or a metal carbon solution.
  • 2. The carbon composite of claim 1, wherein the weight ratio of the at least two carbon microstructures relative to the binding phase is about 1:1 to about 4:1.
  • 3. The carbon composite of claim 1, wherein the binding phase binds the at least two carbon microstructures through mechanical interlocking.
  • 4. The carbon composite of claim 1, wherein each of the at least two carbon microstructures comprises voids having a size of about 20 nm to about 1,000 nm.
  • 5. The carbon composite of claim 4, wherein the carbon microstructures have a thickness of about 1 to about 200 microns, a diameter of about 10 to about 500 microns, and a density of about 0.1 to 2 g/cm3.
  • 6. The carbon composite of claim 1, wherein the carbon microstructures comprise microstructures of graphite.
  • 7. The carbon composite of claim 6, wherein the graphite comprises one or more of the following: expanded graphite; expandable graphite; natural graphite; or synthetic graphite.
  • 8. The carbon composite of claim 1, wherein the carbon microstructures comprise microstructures of expanded graphite.
  • 9. The carbon composite of claim 1, wherein the binder comprises one or more of the following: steel; nickel-chromium based alloys; or nickel-copper based alloys.
  • 10. The carbon composite of claim 1, further comprising one or more of the following: carbon fibers; carbon black; mica; clay; glass fiber; ceramic fibers; or ceramic hollow structures.
  • 11. The carbon composite of claim 1, wherein the interface layer comprises a C—O-metal bond.
  • 12. The carbon composite of claim 1, comprising about 50 to about 80 wt. % of the carbon, based on the total weight of the carbon composite.
  • 13. The carbon composite of claim 1, wherein the carbon composite has a density of about 0.5 to about 10 g/cm3.
  • 14. The carbon composite of claim 1, wherein the composite has at least one of the following properties: the composite has thermal resistance with a range of operation temperatures from about −65° F. up to about 1200° F.;the composition has an elastic elongation of greater than 4%;the composite is chemically resistant to water, oil, brine; and acids;the composite has a hardness from about 50 in SHORE A up to about 75 in SHORE D scale; anda sealing force of a sample of the composite at 15% strain and 600° F. is maintained at about 5800 psi without relaxation for at least 20 minutes.
  • 15. The carbon composite of claim 1, wherein the composite is in the form of a bar, block, sheet, tubular, cylindrical billet, toroid, powder, or pellets.
  • 16. A sheet comprising the carbon composite of claim 1, wherein the sheet has a thickness of about 10 μm to about 10 cm.
  • 17. A powder comprising the carbon composite of claim 1, wherein the powder comprises particles having an average size of about 10 μm to about 1 cm.
  • 18. A plurality of pellets comprising the carbon composite of claim 1, wherein the pellets comprise particles having an average size of about 0.5 cm to about 5 cm.
  • 19. The carbon composite of claim 5, wherein the carbon microstructures comprise microstructures of expanded graphite.
DOMESTIC PRIORITY

This application is a divisional of U.S. patent application Ser. No. 14/488,851, filed Sep. 17, 2014, the disclosure of which is incorporated by reference herein in its entirety.

US Referenced Citations (159)
Number Name Date Kind
3246369 Rhoads et al. Apr 1966 A
3561770 Corsi et al. Feb 1971 A
3666852 Burke May 1972 A
3807996 Sarah Apr 1974 A
3904405 Russell et al. Sep 1975 A
3967935 Frehn Jul 1976 A
3981427 Brookes Sep 1976 A
4116451 Nixon et al. Sep 1978 A
4205858 Shimazaki et al. Jun 1980 A
4234638 Yamazoe et al. Nov 1980 A
4270569 Reay et al. Jun 1981 A
4372393 Baker Feb 1983 A
4383970 Komuro May 1983 A
4426086 Fournie et al. Jan 1984 A
4567103 Sara Jan 1986 A
4582751 Vasilos et al. Apr 1986 A
4743033 Guess May 1988 A
4780226 Sheets et al. Oct 1988 A
4789166 Rericha et al. Dec 1988 A
4798771 Vogel Jan 1989 A
4799956 Vogel Jan 1989 A
4826181 Howard et al. May 1989 A
4885218 Andou et al. Dec 1989 A
5117913 Thernig Jun 1992 A
5134030 Ueda et al. Jul 1992 A
5163692 Schofield et al. Nov 1992 A
5195583 Toon et al. Mar 1993 A
5201532 Salesky et al. Apr 1993 A
5225379 Howard Jul 1993 A
5228701 Greinke et al. Jul 1993 A
5247005 Von Bonin et al. Sep 1993 A
5257603 Bauer et al. Nov 1993 A
5283121 Bordner Feb 1994 A
5286574 Foster et al. Feb 1994 A
5362074 Gallo et al. Nov 1994 A
5392982 Li Feb 1995 A
5455000 Seyferth et al. Oct 1995 A
5467814 Hyman et al. Nov 1995 A
5494753 Anthony Feb 1996 A
5495979 Sastri et al. Mar 1996 A
5499827 Suggs et al. Mar 1996 A
5509555 Chiang et al. Apr 1996 A
5522603 Naitou et al. Jun 1996 A
5597168 Antonini Jan 1997 A
5730444 Notter Mar 1998 A
5765838 Ueda et al. Jun 1998 A
5791657 Cain et al. Aug 1998 A
5968653 Coppella et al. Oct 1999 A
5992857 Ueda et al. Nov 1999 A
6020276 Hoyes et al. Feb 2000 A
6027809 Ueda et al. Feb 2000 A
6065536 Gudmestad et al. May 2000 A
6075701 Ali et al. Jun 2000 A
6105596 Hoyes et al. Aug 2000 A
6128874 Olson et al. Oct 2000 A
6131651 Richey, III Oct 2000 A
6152453 Kashima et al. Nov 2000 A
6161838 Balsells Dec 2000 A
6182974 Harrelson Feb 2001 B1
6183667 Kubo et al. Feb 2001 B1
6234490 Champlin May 2001 B1
6258457 Ottinger et al. Jul 2001 B1
6273431 Webb Aug 2001 B1
6383656 Kimura May 2002 B1
6506482 Burton et al. Jan 2003 B1
6585053 Coon et al. Jul 2003 B2
6789634 Denton Sep 2004 B1
6880639 Rhodes et al. Apr 2005 B2
6933531 Ishikawa Aug 2005 B1
7105115 Shin Sep 2006 B2
7132077 Norville Nov 2006 B2
7138190 Bauer et al. Nov 2006 B2
7470468 Mercuri et al. Dec 2008 B2
7666469 Weintritt et al. Feb 2010 B2
7758783 Shi et al. Jul 2010 B2
9325012 Xu et al. Apr 2016 B1
20010003389 Pippert Jun 2001 A1
20010039966 Walpole et al. Nov 2001 A1
20020114952 Ottinger et al. Aug 2002 A1
20020140180 Waltenberg et al. Oct 2002 A1
20030137112 Richter et al. Jul 2003 A1
20040043220 Hirose et al. Mar 2004 A1
20040097360 Benitsch et al. May 2004 A1
20040127621 Drzal et al. Jul 2004 A1
20040155382 Huang et al. Aug 2004 A1
20040186201 Stoffer et al. Sep 2004 A1
20040256605 Reinheimer et al. Dec 2004 A1
20060042801 Hackworth et al. Mar 2006 A1
20060220320 Potier et al. Oct 2006 A1
20060241237 Drzal Oct 2006 A1
20060249917 Kosty Nov 2006 A1
20060272321 Mockenhaupt et al. Dec 2006 A1
20070009725 Noguchi et al. Jan 2007 A1
20070054121 Weintritt et al. Mar 2007 A1
20070243407 Delannay Oct 2007 A1
20070257405 Freyer Nov 2007 A1
20080128067 Sayir et al. Jun 2008 A1
20080152577 Addiego Jun 2008 A1
20080175764 Sako Jul 2008 A1
20080279710 Zhamu et al. Nov 2008 A1
20080289813 Gewily et al. Nov 2008 A1
20090059474 Zhamu et al. Mar 2009 A1
20090075120 Cornie et al. Mar 2009 A1
20090130515 Son et al. May 2009 A1
20090151847 Zhamu et al. Jun 2009 A1
20090302552 Leinfelder et al. Jun 2009 A1
20090194205 Loffler et al. Aug 2009 A1
20100003530 Ganguli et al. Jan 2010 A1
20100098956 Sepeur et al. Apr 2010 A1
20100122821 Corre et al. May 2010 A1
20100143690 Romero et al. Jun 2010 A1
20100159357 Otawa Jun 2010 A1
20100163782 Chang et al. Jul 2010 A1
20100203161 Gehri Aug 2010 A1
20100203340 Ruoff et al. Aug 2010 A1
20100207055 Ueno et al. Aug 2010 A1
20100266790 Kusinski et al. Oct 2010 A1
20110033721 Rohatgi Feb 2011 A1
20110045724 Bahukudumbi Feb 2011 A1
20110140365 Dietle et al. Jun 2011 A1
20110157772 Zhamu et al. Jun 2011 A1
20110187058 Curry et al. Aug 2011 A1
20110200825 Chakraborty et al. Aug 2011 A1
20110278506 Toyokawa Nov 2011 A1
20120107590 Xu et al. May 2012 A1
20120205873 Turley Aug 2012 A1
20130001475 Christ et al. Jan 2013 A1
20130045423 Lim et al. Feb 2013 A1
20130096001 Choi et al. Apr 2013 A1
20130114165 Mosendz et al. May 2013 A1
20130284737 Ju et al. Oct 2013 A1
20130287326 Porter et al. Oct 2013 A1
20130292138 Givens et al. Nov 2013 A1
20140051612 Mazyar et al. Feb 2014 A1
20140127526 Etschmaier et al. May 2014 A1
20140224466 Lin et al. Aug 2014 A1
20140272592 Thompkins et al. Sep 2014 A1
20150027567 Shreve et al. Jan 2015 A1
20150034316 Hallundbäk et al. Feb 2015 A1
20150068774 Hallundbäk et al. Mar 2015 A1
20150158773 Zhao et al. Jun 2015 A1
20150267816 Boskovski Sep 2015 A1
20160032671 Xu et al. Feb 2016 A1
20160089648 Xu et al. Mar 2016 A1
20160108703 Xu et al. Apr 2016 A1
20160130519 Lei et al. May 2016 A1
20160136923 Zhao et al. May 2016 A1
20160136928 Zhao et al. May 2016 A1
20160138359 Zhao et al. May 2016 A1
20160145965 Zhao et al. May 2016 A1
20160145966 Zhao et al. May 2016 A1
20160145967 Zhao et al. May 2016 A1
20160146350 Zhao et al. May 2016 A1
20160160602 Ruffo Jun 2016 A1
20160176764 Xu et al. Jun 2016 A1
20160186031 Zhao et al. Jun 2016 A1
20160333657 Zhao et al. Nov 2016 A1
20170321069 Zhao et al. Nov 2017 A1
20170342802 Zhao et al. Nov 2017 A1
Foreign Referenced Citations (23)
Number Date Country
2429780 Dec 2003 CA
0539011 Apr 1993 EP
0747615 Oct 2001 EP
2056004 May 2009 EP
2586963 May 2013 EP
S5424910 Feb 1979 JP
S5491507 Jul 1979 JP
S58181713 Oct 1983 JP
S59129142 Jul 1984 JP
S6131355 Feb 1986 JP
H0238365 Feb 1990 JP
H0616404 Jan 1994 JP
2014141746 Aug 2014 JP
9403743 Feb 1994 WO
03102360 Dec 2003 WO
2004015150 Feb 2004 WO
2005115944 Dec 2005 WO
2007138409 Dec 2007 WO
2008021033 Feb 2008 WO
2011039531 Apr 2011 WO
2014028149 Feb 2014 WO
2015021627 Feb 2015 WO
2016085594 Jun 2016 WO
Non-Patent Literature Citations (10)
Entry
Baxter et al., “Microstructure and solid particle erosion of carbon-based materials used for the protection of highly porous carbon-carbon composite thermal insulation”, Journal of Materials Science, vol. 32, 1997, pp. 4485-4492.
Etter et al., “Aluminium carbide formation in interpenetrating graphite/aluminium composites”, Materials Science and Engineering, Mar. 15, 2007, vol. 448, No. 1, pp. 1-6.
Hutsch et al., “Innovative Metal-Graphite Composites as Thermally Conducting Materials”, PM2010 World Congress—PM Functional Materials—Heat Sinks, 2010, 8 pages.
Levin et al., “Solid Particle Erosion Resistance and High Strain Rate Deformation Behavior of Inconel-625 Alloy”, Superalloys 718, 625, 706 and Various Derivatives, The Minerals, Metals & Materials Society, 1997, 10 pages.
Miyamoto et al., “Development of New Composites; Ceramic Bonded Carbon”, Transactions of JWRI, vol. 38, No. 2, 2009, pp. 57-61.
Moghadam et al, “Functional Metal Matrix Composites: Self-lubricating, Self-healing, and Nanocomposites—An Outlook”, The Minerals, Metals & Materials Society, Apr. 5, 2014, 10 pages.
Pohlmann et al., “Magnesium alloy-graphite composites with tailored heat conduction properties for hydrogen storage applications”, International Journal of Hydrogen Energy, 35 (2010), pp. 12829-12836.
Rashad et al. “Effect of of Graphene Nanoplatelets addition on mechanical properties of pure aluminum using a semi-powder method”, Materials International, Apr. 20, 2014, vol. 24, pp. 101-108.
Tikhomirov et al., “The chemical vapor infiltration of exfoliated graphite to produce carbon/carbon composites”, Carbon, 49 (2011), pp. 147-153.
Yang et al., “Effect of tungsten addition on thermal conductivity of graphite/copper composites”, Composites Part B: Engineering, May 31, 2013, vol. 55, pp. 1-4.
Related Publications (1)
Number Date Country
20160176764 A1 Jun 2016 US
Divisions (1)
Number Date Country
Parent 14488851 Sep 2014 US
Child 15059351 US