(19)
(11)EP 3 080 047 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
02.10.2019 Bulletin 2019/40

(21)Application number: 14870030.5

(22)Date of filing:  13.11.2014
(51)International Patent Classification (IPC): 
C04B 35/536(2006.01)
C04B 35/532(2006.01)
C01B 32/05(2017.01)
(86)International application number:
PCT/US2014/065389
(87)International publication number:
WO 2015/088698 (18.06.2015 Gazette  2015/24)

(54)

CARBON COMPOSITES AND METHODS OF MANUFACTURE

KOHLENSTOFFVERBUNDSTOFFE UND VERFAHREN ZUR HERSTELLUNG

COMPOSITES DE CARBONE ET LEURS PROCÉDÉS DE FABRICATION


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 11.12.2013 US 201314103095
06.11.2014 US 201414534356

(43)Date of publication of application:
19.10.2016 Bulletin 2016/42

(73)Proprietor: Baker Hughes, a GE company, LLC
Houston, TX 77073 (US)

(72)Inventors:
  • ZHAO, Lei
    Houston, TX 77019-2118 (US)
  • XU, Zhiyue
    Houston, TX 77019-2118 (US)

(74)Representative: BRP Renaud & Partner mbB Rechtsanwälte Patentanwälte Steuerberater 
Königstraße 28
70173 Stuttgart
70173 Stuttgart (DE)


(56)References cited: : 
US-A- 4 799 956
US-A1- 2002 114 952
US-A1- 2005 202 245
US-A1- 2009 059 474
US-A1- 2011 157 772
US-A- 5 247 005
US-A1- 2004 127 621
US-A1- 2008 279 710
US-A1- 2010 003 530
  
  • YANG, W. ET AL.: 'Effect of tungsten addition on thermal conductivity of graphite/copper composites' COMPOSITES PART B: ENGINEERING vol. 55, 31 May 2013, pages 1 - 4, XP028713069
  • ETTER, T. ET AL.: 'Aluminium carbide formation in interpenetrating graphite/ aluminium composites' MATERIALS SCIENCE AND ENGINEERING: A vol. 448, no. 1, 15 March 2007, pages 1 - 6, XP005879837
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

BACKGROUND



[0001] This disclosure is directed to carbon composites, and in particular to carbon composites comprising expanded graphite, their methods of manufacture, and articles formed therefrom.

[0002] Elastomers are relatively soft and deformable, thus have been widely used in seals, adhesives, and molded flexible parts. Elastomers have also been used as sealing materials in downhole applications. However, as oil and gas production activities continue to shift toward more hostile and unconventional environments, the performance of elastomers becomes less than satisfactory as they are susceptible to decomposition under harsh conditions, posing limits for heavy oil exploration.

[0003] Metals have been proposed as alternative sealing materials for downhole applications due to their high corrosion resistance and excellent high pressure and high temperature tolerance. However, metals have low ductility and low elasticity. Accordingly, metals are less effective in sealing rough casing surfaces as compared to elastomers.

[0004] Carbon materials such as flexible graphite could be one of the promising alternative sealing materials to replace elastomers or metals due to their high thermal and chemical stability, flexibility, compressibility, and conformability. However, certain carbon materials may have weak mechanical strength affecting the structural integrity of the element and tools comprising these materials.

[0005] Therefore, there remains a need in the art for sealing materials that have a good balance of properties such as stability, elasticity, and mechanical strength.

[0006] US 2009/059474 is concerned with a graphite-carbon composite electrode for supercapacitors.

[0007] US 2008/279710 is concerned with a method of producing exfoliated graphite composite compositions for fuel cell flow field plates.

BRIEF DESCRIPTION



[0008] According to an aspect of the present invention, there is provided a carbon composite as claimed in claim 1.

[0009] According to another aspect of the present invention, there is provided a method of forming a carbon composite as claimed in claim 6. Optionally the filler has an average particle size of about 0.05 to about 250 microns.

[0010] An article comprising the carbon composite is also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS



[0011] The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIGs. 1(a)-1(c) are scanning electron microscopic ("SEM") images of an expanded graphite structure before (1(a)) and after (1(b) and 1(c)) compression;

FIG. 2 is a schematic illustration of exemplary mechanisms to enhance the mechanical strength of expanded graphite;

FIG. 3 is a flow chart illustrating the formation of a carbon composite via a thermal diffusion process;

FIG. 4 is a flow chart illustrating the formation of a carbon composite via a vapor deposition process; and

FIG. 5 is a flow chart illustrating the formation of a carbon composite via polymer carbonization.


DETAILED DESCRIPTION



[0012] Graphites are made up of layer planes of hexagonal arrays or networks of carbon atoms. These layer planes of hexagonally arranged carbon atoms are substantially flat and are oriented or ordered so as to be substantially parallel and equidistant to one another. The substantially flat, parallel equidistant sheets or layers of carbon atoms are usually referred to as basal planes. Accordingly, graphites may be characterized as laminated structures of carbon.

[0013] The basal planes of graphite are held together by weak van der Waals forces. Graphites, especially natural graphites, can be treated so that the spacing between the superposed carbon layers or laminae can be appreciably opened up so as to provide a marked expansion in the direction perpendicular to the layers, thus form an expanded graphite structure in which the laminar character of the carbon layers is substantially retained.

[0014] In considering the graphite or expanded graphite structure, two axes or directions are usually noted: the "c" axis or direction and the "a" axes or directions. The "c" axis or direction may be considered as the direction perpendicular to the carbon layers. The "a" axes or directions may be considered as the directions parallel to the carbon layers or the directions perpendicular to the "c" direction.

[0015] The expanded graphite particles are vermiform in appearance, and are therefore commonly referred to as worms. Figure 1(a) is a microscopic ("SEM") image of an expanded graphite structure. As shown in figure 1(a), the expanded graphite comprises parallel basal planes perpendicular to the axis of the worm.

[0016] The worms may be compressed together into articles, which unlike the original graphite, are flexible, and have good elastic properties. However, during compression, these worm-like particles collapse and are orientated in such a way that the basal planes of the expanded graphite particles are substantially perpendicular to the compression direction. Without wishing to be bound by theory, it is believed that there are only weak Van de Waals forces exist between basal planes within an expanded graphite particle, and there are no forces exist between basal planes of different expanded graphite particles, thus the expanded graphite bulk materials have weak mechanical strength. Figures (1b) and (1c) are SEM images of an expanded graphite structure after compression.

[0017] Applicants have found methods to improve the mechanical strength of expanded graphite bulk materials. Advantageously, the methods enhance the mechanical strength of the expanded graphite at the basal plane level by introducing a second phase into the worm-like structure of expanded graphite rather than onto the surface of the structure. The second phase can bond basal planes within one expanded graphite particle as illustrated as mechanism A in figure 2. Alternatively, the second phase bonds basal planes of the same graphite particle as well as basal planes of different graphite particles. This mechanism is illustrated in figure 2 as mechanism B.

[0018] One way of forming a second phase at the basal plane level is to compress a combination comprising expanded graphite particles and a filler to provide a pre-form; and to heat the pre-form to a temperature which is 20°C to 100°C higher than the melting point of the filler thus forming a second phase bonding at least two adjacent basal planes of the same expanded graphite particle together.

[0019] The expanded graphite can be synthesized by chemical intercalation of natural graphite and sudden expansion at high temperature. In an embodiment, the expanded graphite is produced through the steps of: treating a graphite material such as natural graphite, kish graphite, pyrolytic graphite, etc., with sulfuric acid, nitric acid, chromic acid, boric acid, or halides such as FeCl3, ZnCl2, SbCl5, to form an expandable graphite; and rapidly heating the expandable graphite at a high temperature of, e.g., 800 °C or higher, so as to generate pyrolysis gas whose pressure is used to expand a space between graphite layers thereby forming the expanded graphite.

[0020] The expanded graphite particles can have any shape or size suitable for their intended use. As used herein, "graphite particles" includes graphite grains, graphite flakes, or graphite crystals.

[0021] The expanded graphite particles are mixed evenly with a filler to provide a combination. The mixing can be accomplished by any known mixing method to thoroughly disperse the filler throughout the graphite particles. The filler includes SiO2, Si, B, B2O3, or a metal or an alloy. The metal is aluminum, copper, titanium, nickel, tungsten, chromium, or iron. The alloy includes the alloys of aluminum, copper, titanium, nickel, tungsten, chromium, or iron. One exemplary alloy is steel. These materials can be in different shapes, such as particles, fibers, and wires. Combinations of the materials can be used. In an embodiment, the filler 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 filler has a size within these ranges, it disperses uniformly among the expanded graphite particles. Particle size can be determined by an appropriate method of sizing particles such as, for example, static or dynamic light scattering (SLS or DLS) using a laser light source.

[0022] In the combination, the expanded graphite particles is present in an amount of 25 wt.% to 95 wt.% or 50 wt.% to 80 wt.%, based on the total weight of the combination. The filler is present in an amount of 5 wt.% to 75 wt.% or 20 wt.% to 50 wt.%, based on the total weight of the combination.

[0023] Next, the combination comprising the expanded graphite particles and the filler is compressed to provide a pre-form. Optionally the pre-form comprises pores. After the filler is melted, the filler can fill the pores and maximize its contact with the expanded graphite particles.

[0024] The pre-form can be heated at a temperature that is 20°C to 100°C higher or 20°C to 50°C higher than the melting point of the filler for 5 minutes to 3 hours or 30 minutes to 3 hours. The heating can be conducted at an atmospheric pressure or at a super-atmospheric pressure of 34.47 MPa (5,000 psi) to 206.84 MPa (30,000 psi). The heating can also be conducted under an inert atmosphere, for example, under argon or nitrogen. The means of heating is not particularly limited. In an embodiment, the heating is conducted in an oven.

[0025] Without wishing to be bound theory, it is believed that under the process conditions, the filler penetrates the walls of the worm-like structures of expanded graphite particles and reacts with the carbon of expanded graphite forming a carbide thus bonding the basal planes together. The filler can also be present at the boundaries of different expanded graphite particles. Thus the second phase can further bond at least one basal plane of a graphite particle with at least one basal plane of a different graphite particle. In an embodiment, the second phase is a continuous matrix holding different graphite particles as well as the basal planes of the same graphite particle together.

[0026] The second phase comprises a metallic carbide, for example, a carbide of aluminum, titanium, nickel, tungsten, chromium, iron, an aluminum alloy, a copper alloy, a titanium alloy, a nickel alloy, a tungsten alloy, a chromium alloy, or an iron alloy. These carbides are formed by reacting the corresponding metal or metal alloy with the basal plane carbon of the expanded graphite. The second phase can also comprise SiC formed by reacting SiO2 or Si with the carbon of expanded graphite, or B4C formed by reacting B or B2O3 with the carbon of expanded graphite. The second phase can comprise a combination of these carbides when a combination of filler materials is used.

[0027] An exemplary scheme to prepare a carbon composite according to this method is illustrated in figure 3. As shown in figure 3, expanded graphite and metal power is mixed and compressed to form a pre-form. Then the pre-formed is heated causing the metal to be disposed between the basal planes of the same graphite particle as well as the basal planes of different graphite particles through infiltration and penetration. The heat treatment also causes the metal to react with the carbon of the expanded graphite thus forming the final composite.

[0028] In another embodiment, a method for the manufacture of a carbon composite comprises providing a plurality of expanded graphite particles; depositing a filler on a basal plane of an expanded graphite particle through vapor deposition to provide a filled-expanded graphite; compressing the filled-expanded graphite to provide a pre-form; and heating the pre-form to form a second phase bonding at least two adjacent basal planes of the same expanded graphite particle together.

[0029] The expanded graphite and the filler have been described hereinabove. The filler can be deposited on the basal planes of an expanded graphite particle by vapor deposition. A "vapor deposition" process refers to a process of depositing materials on a substrate through the vapor phase. Vapor deposition processes include physical vapor deposition, chemical vapor deposition, atomic layer deposition, laser vapor deposition, and plasma-assisted vapor deposition. Examples of the filler precursors include triethylaluminum and nickel carbonyl. Different variations of physical deposition, chemical deposition, and plasma-assisted vapor deposition can be used. Exemplary deposition processes can include plasma assisted chemical vapor deposition, sputtering, ion beam deposition, laser ablation, or thermal evaporation. Without wishing to be bound by theory, it is believed that the worm-like structure of expanded graphite is a highly porous structure with strong absorption capacity, thus the filler precursor gases can diffuse through the worm wall and form the filler deposited on the basal planes of the expanded graphite.

[0030] The vapor deposition provides a filled-expanded graphite, which can be in the form of a powder. The filled-expanded graphite can be compressed to form a pre-form. The pre-form is then heated to allow the filler to react with the carbon of the expanded graphite thus forming a second phase holding the basal planes of an expanded graphite particle together.

[0031] The heating temperature is higher than the melting point of the filler. Under this circumstance, the second phase comprises carbides formed by liquid phase bonding. In an embodiment, the heating temperature is 600°C to 1400 or 600°C to 1000°C. The heating can be conducted at an atmospheric pressure or at a super-atmospheric pressure of 5,000 psi to 30,000 psi. The heating can also be conducted under an inert atmosphere, for example, under argon or nitrogen.

[0032] The amount of the filler in the carbon composite can vary depending on the concentration of the deposition material, the vapor deposition temperature, and the time that the expanded graphite is left in a vapor deposition reactor. The filler can be present in an amount of 2 wt.% to 50 wt.% or 10 wt.% to 25 wt.%, based on the total weight of the carbon composite. The expanded graphite can be present in an amount of 50 wt.% to 98 wt.% or 75 wt.% to 90 wt.%, based on the total weight of the carbon composite.

[0033] An exemplary scheme to prepare a carbon composite according to this method is illustrated in figure 4. As shown in figure 4, metal is deposited on the basal planes of expanded graphite through vapor deposition techniques. After compressing, the pre-form is heated causing metal to react with carbon of the expanded graphite thus forming the final composite.

[0034] A method for the manufacture of a carbon composite can also comprise compressing a combination comprising expanded graphite particles, a filler, a crosslinkable polymer, and a crosslinker to provide a pre-form; crosslinking the crosslinkable polymer with the crosslinker to provide a composition comprising a crosslinked polymer; heating the composition to form a carbonization product of the crosslinked polymer; wherein the carbonization product bonds at least two adjacent basal planes of the same expanded graphite particle together; and the carbonization product further bonds at least one basal plane of a graphite particle with at least one basal plane of a different graphite particle. An exemplary scheme to prepare a carbon composite according to this method is illustrated in figure 5.

[0035] The crosslinkable polymer is selected from a polyphenol, polyacrylonitrile, an epoxy resin, a rayon, a pitch, or a combination comprising at least one of the foregoing. Exemplary crosslinkers include amines, cyclic acid anhydrides, and the like. The combination can comprise 2 wt.% to 50 wt.% of the crosslinkable polymer, 2 wt.% to 20 wt.% of the filler, and 30 wt.% to 96 wt.% of the expanded graphite particles.

[0036] The crosslinking conditions can vary depending on the specific crosslinkable polymer and the crosslinker used. In an embodiment, the crosslinking is conducted at a temperature of 50°C to 300°C, specifically 100°C to 200°C.

[0037] The composition comprising the crosslinked polymer, the expanded graphite particles, and the filler can be heated to a temperature of 700°C to 1,400 °C or 700°C to 1,200°C, specifically 800°C to 1,000°C, under which temperature, the crosslinked polymer forms a carbonization product bonding the basal planes of the expanded graphite together.

[0038] As used herein, "carbonization" refers to the conversion of a polymer into carbon and/or a carbon-containing residue. A "carbonization product" refers to an amorphous carbon and/or a carbon-containing residue. By converting the crosslinked polymer into a carbonization product, the basal planes are bonded together through carbon-carbon bonds.

[0039] The disclosure also provides a carbon composite made by the above described methods. The composite comprises a plurality of expanded graphite particles; and a second phase comprising a carbide; wherein the second phase bonds at least two adjacent basal planes of the same expanded graphite particle together. An amount of the expanded graphite particles can be 50 to 98 wt.%, based on the total weight of the carbon composite.

[0040] The second phase can further bond at least one basal plane of a graphite particle with at least one basal plane of a different graphite particle. An amount of the expanded graphite particles is 25 to 95 wt.%, based on the total weight of the carbon composite.

[0041] The second phase may comprise a carbide of aluminum, titanium, nickel, tungsten, chromium, iron, an aluminum alloy, a copper alloy, a titanium alloy, a nickel alloy, a tungsten alloy, a chromium alloy, or an iron alloy, or SiC, or B4C. In addition to the second phase, the composite comprises a filler selected from SiO2, Si, B, B2O3, a metal selected from aluminum, copper, titanium, nickel, tungsten, chromium, or iron, an alloy of the metal, or a combination comprising at least one of the foregoing.

[0042] In an embodiment, the second phase comprises a carbonization product of a crosslinked polymer, which is not claimed. The croslinked polymer is derived from a polyphenol, polyacrylonitrile, an epoxy resin, a rayon, a pitch, or a combination comprising at least one of the foregoing. The composite comprises a filler selected from SiO2, Si, B, B2O3, a metal selected from aluminum, copper, titanium, nickel, tungsten, chromium, or iron, an alloy of the metal, or a combination comprising at least one of the foregoing. The carbon composite comprises 2 wt.% to 50 wt.% of the filler, 2 wt.% to 20 wt.% of the second phase, and 30 wt.% to 96 wt.% of the expanded graphite particles.

[0043] Articles can be made from the carbon composites. Thus, in an embodiment, an article comprises the carbon composite. The carbon composite may be used to form all or a portion of an article. 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, The article can be a downhole element. In an embodiment, the article is a packer, a seal, or an O-ring.

[0044] 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). "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.

[0045] 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).

[0046] Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.


Claims

1. A carbon composite comprising:

a plurality of expanded graphite particles; and

a second phase comprising a carbide;

the second phase bonding at least two adjacent basal planes of the same expanded graphite particle together,

wherein the carbon composite further comprises a filler selected from SiO2, Si, B, B2O3, a metal selected from aluminum, copper, titanium, nickel, tungsten, chromium, or iron, an alloy of the metal, or a combination comprising at least one of the foregoing materials.


 
2. The carbon composite of claim 1, wherein the second phase comprises a carbide of aluminum, titanium, nickel, tungsten, chromium, iron, an aluminum alloy, a copper alloy, a titanium alloy, a nickel alloy, a tungsten alloy, a chromium alloy, an iron alloy, SiC, B4C, or a combination comprising at least one of the foregoing carbides.
 
3. The carbon composite of claim 1, wherein an amount of the expanded graphite particles is 50 to 98 wt.%, based on the total weight of the carbon composite.
 
4. The carbon composite of claim 1 or 2, wherein the second phase further bonds at least one basal plane of a graphite particle with at least one basal plane of a different graphite particle.
 
5. The carbon composite of claim 4, wherein an amount of the expanded graphite particles is 25 to 95 wt.%, based on the total weight of the carbon composite.
 
6. A method for the manufacture of a carbon composite, the method comprising:

compressing a combination comprising expanded graphite particles and a filler to provide a pre-form; and

heating the pre-form to a temperature which is 20°C to 100°C higher than the melting point of the filler to form a second phase bonding at least two adjacent basal planes of the same expanded graphite particle together, the second phase comprising a carbide;

wherein the filler is selected from SiO2, Si, B, B2O3, a metal selected from aluminum, copper, titanium, nickel, tungsten, chromium, or iron, an alloy of the metal, or a combination comprising at least one of the foregoing materials.


 
7. The method of claim 6, wherein the filler has an average particle size of about 0.05 to about 250 microns.
 
8. The method of claim 6 or 7, wherein the second phase further bonds at least one basal plane of a graphite particle with at least one basal plane of a different graphite particle.
 
9. The method of claim 6 or 7, wherein:

the heating is conducted for 5 minutes to 3 hours; and/or

the heating is conducted at a pressure of 34.47 MPa (5,000 psi) to 206.84 MPa (30,000 psi).


 
10. The method of claim 6 or 7, wherein the combination comprises 20 wt.% to 50 wt.% of the filler and 50 wt.% to 80 wt.% of the expanded graphite particles, based on the total weight of the combination.
 
11. An article comprising the carbon composite of claim 1.
 
12. The article of claim 11, wherein the article comprises seals, components of frac plug, bridge plug, packing elements, expanding packing elements, O-rings, bonded seals, bullet seals, subsurface safety valve dynamic seals, subsurface safety valve flapper seals, V rings, back up rings, drill bit seals, or ESP seals.
 


Ansprüche

1. Kohlenstoffverbundstoff, umfassend:

eine Vielzahl von expandierten Graphitteilchen und

eine zweite Phase, die ein Carbid umfasst;

wobei die zweite Phase mindestens zwei aneinander angrenzende Basisebenen desselben expandierten Graphitteilchens miteinander verbindet,

wobei der Kohlenstoffverbundstoff ferner einen Füllstoff umfasst, der ausgewählt ist aus SiO2, Si, B, B2O3, einem Metall, das ausgewählt ist aus Aluminium, Kupfer, Titan, Nickel, Wolfram, Chrom oder Eisen, einer Legierung des Metalls oder einer Kombination, die mindestens eines der vorgenannten Materialien umfasst.


 
2. Kohlenstoffverbundstoff nach Anspruch 1, wobei die zweite Phase ein Carbid von Aluminium, Titan, Nickel, Wolfram, Chrom, Eisen, einer Aluminiumlegierung, einer Kupferlegierung, einer Titanlegierung, einer Nickellegierung, einer Wolframlegierung, einer Chromlegierung, einer Eisenlegierung, SiC, B4C oder eine Kombination aus mindestens einem der vorgenannten Carbide umfasst.
 
3. Kohlenstoffverbundstoff nach Anspruch 1, wobei eine Menge der expandierten Graphitteilchen, bezogen auf das Gesamtgewicht des Kohlenstoffverbundstoffs, 50 bis 98 Gew.-% beträgt.
 
4. Kohlenstoffverbundstoff nach Anspruch 1 oder 2, wobei die zweite Phase ferner mindesten eine Basisebene eines Graphitteilchens an mindestens eine Basisebene eines anderen Graphitteilchens bindet.
 
5. Kohlenstoffverbundstoff nach Anspruch 4, wobei eine Menge der expandierten Graphitteilchen, bezogen auf das Gesamtgewicht des Kohlenstoffverbundstoffs, 25 bis 95 Gew.-% beträgt.
 
6. Verfahren zur Herstellung eines Kohlenstoffverbundstoffs, wobei das Verfahren umfasst:

Komprimieren einer Kombination, die expandierte Graphitteilchen und einen Füllstoff umfasst, um eine Vorform bereitzustellen; und

Erhitzen der Vorform auf eine Temperatur, die um 20 °C bis 100 °C höher ist als der Schmelzpunkt des Füllstoffs, zur Bildung einer zweiten Phase, die mindestens zwei aneinander angrenzende Basisebenen desselben expandierten Graphitteilchens aneinander bindet, wobei die zweite Phase ein Carbid umfasst;

wobei der Füllstoff ausgewählt ist aus SiO2, Si, B, B2O3, einem Metall, das ausgewählt ist aus Aluminium, Kupfer, Titan, Nickel, Wolfram, Chrom oder Eisen, einer Legierung des Metalls oder einer Kombination, die mindestens eines der vorgenannten Materialien umfasst.


 
7. Verfahren nach Anspruch 6, wobei der Füllstoff eine durchschnittliche Teilchengröße von etwa 0,05 bis etwa 250 Mikrometer aufweist.
 
8. Verfahren nach Anspruch 6 oder 7, wobei die zweite Phase ferner mindestens eine Basisebene eines Graphitteilchens an mindestens eine Basisebene eines anderen Graphitteilchens bindet.
 
9. Verfahren nach Anspruch 6 oder 7, wobei:

das Erwärmen für 5 Minuten bis 3 Stunden durchgeführt wird und/oder

das Erwärmen bei einem Druck von 34,47 MPa (5.000 psi) bis 206,84 MPa (30.000 psi) durchgeführt wird.


 
10. Verfahren nach Anspruch 6 oder 7, wobei die Kombination, bezogen auf das Gesamtgewicht der Kombination, 20 Gew.-% bis 50 Gew.-% Füllstoff und 50 Gew.-% bis 80 Gew.-% expandierte Graphitteilchen umfasst.
 
11. Gegenstand, den Kohlenstoffverbundstoff nach Anspruch 1 umfassend.
 
12. Gegenstand nach Anspruch 11, wobei der Gegenstand Dichtungen, Komponenten eines Frac-Plugs, eines Brückensteckers, Packungselemente, expandierende Packungselemente, O-Ringe, Klebdichtungen, Kugeldichtungen, dynamische Untertage-Sicherheitsventildichtungen, Untertage-Sicherheitsventil-Klappendichtungen, V-Ringe, Stützringe, Bohrerdichtungen oder ESP-Dichtungen umfasst.
 


Revendications

1. Composite de carbone comprenant :

une pluralité de particules de graphite expansé ; et

une deuxième phase comprenant un carbure ;

la deuxième phase liant au moins deux plans basaux adjacents de la même particule de graphite expansé ensemble,

dans lequel le composite de carbone comprend en outre une charge choisie parmi SiO2, Si, B, B2O3, un métal choisi parmi l'aluminium, le cuivre, le titane, le nickel, le tungstène, le chrome, ou le fer, un alliage du métal, ou une combinaison comprenant au moins l'un des matériaux qui précèdent.


 
2. Composite de carbone selon la revendication 1, dans lequel la deuxième phase comprend un carbure d'aluminium, du titane, du nickel, du tungstène, du chrome, du fer, un alliage d'aluminium, un alliage de cuivre, un alliage de titane, un alliage de nickel, un alliage de tungstène, un alliage de chrome, un alliage de fer, du SiC, du B4C, ou une combinaison comprenant au moins l'un des carbures qui précèdent.
 
3. Composite de carbone selon la revendication 1, dans lequel une quantité des particules de graphite expansé est de 50 à 98 % en poids, sur la base du poids total du composite de carbone.
 
4. Composite de carbone selon la revendication 1 ou 2, dans lequel la deuxième phase lie en outre au moins un plan basal d'une particule de graphite avec au moins un plan basal d'une particule de graphite différente.
 
5. Composite de carbone selon la revendication 4, dans lequel une quantité des particules de graphite expansé est de 25 à 95 % en poids, sur la base du poids total du composite de carbone.
 
6. Procédé de fabrication d'un composite de carbone, le procédé comprenant :

la compression d'une combinaison comprenant des particules de graphite expansé et une charge pour fournir une préforme ; et

le chauffage de la préforme à une température qui est de 20 °C à 100 °C supérieure au point de fusion de la charge pour former une deuxième phase liant au moins deux plans basaux adjacents de la même particule de graphite expansé ensemble, la deuxième phase comprenant un carbure ;

dans lequel la charge est choisie parmi SiO2, Si, B, B2O3, un métal choisi parmi l'aluminium, le cuivre, le titane, le nickel, le tungstène, le chrome, ou le fer, un alliage du métal, ou une combinaison comprenant au moins l'un des matériaux qui précèdent.


 
7. Procédé selon la revendication 6, dans lequel la charge a une taille moyenne de particule d'environ 0,05 à environ 250 microns.
 
8. Procédé selon la revendication 6 ou 7, dans lequel la deuxième phase lie en outre au moins un plan basal d'une particule de graphite avec au moins un plan basal d'une particule de graphite différente.
 
9. Procédé selon la revendication 6 ou 7, dans lequel :

le chauffage est réalisé pendant 5 minutes à 3 heures ; et/ou

le chauffage est effectué à une pression de 34,47 MPa (5 000 psi) à 206,84 MPa (30 000 psi).


 
10. Procédé selon la revendication 6 ou 7, dans lequel la combinaison comprend de 20 % en poids à 50 % en poids de la charge et de 50 % en poids à 80 % en poids des particules de graphite expansé, sur la base du poids total de la combinaison.
 
11. Article comprenant le composite de carbone selon la revendication 1.
 
12. Article selon la revendication 11, dans lequel l'article comprend des joints, des composants de bouchon de fracturation, un bouchon de support, des éléments d'emballage, des éléments d'emballage expansés, des joints toriques, des bagues composites, des joints de type balle, des joints dynamiques de soupape de sécurité de subsurface, des joints de soupape de sécurité à battant de subsurface, des joints en V, des bagues antiextrusion, des joints de foret, ou des joints ESP.
 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



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Patent documents cited in the description