Patent Grant
8501144
Apparatuses comprising polycrystalline diamond are utilized for a variety of applications and in a corresponding variety of mechanical systems. Generally, polycrystalline diamond elements are used in drilling tools (e.g., inserts, cutting elements, gage trimmers, etc.), machining equipment, bearing apparatuses, wire drawing machinery, and in other mechanical systems. More specifically, polycrystalline diamond compacts have found utility as cutting elements in drill bits (e.g., roller cone drill bits and fixed cutter drill bits).
A polycrystalline diamond compact (“PDC”) typically includes a diamond layer or table formed by a sintering process employing high temperature and high pressure conditions that causes the diamond table to become bonded to a substrate (such as cemented tungsten carbide substrate), as described in greater detail below. Optionally, the substrate may be brazed or otherwise joined to an attachment member such as a stud or to a cylindrical backing, if desired. A PDC may be employed as a subterranean cutting element mounted to a drill bit either by press-fitting, brazing, or otherwise locking the stud into a receptacle defined by the drill bit, or by brazing the cutting element directly into a preformed pocket, socket, or other receptacle formed in the subterranean drill bit. In one example, cutter pockets may be formed in the face of a matrix-type bit comprising tungsten carbide particles that are infiltrated or cast with a binder (e.g., a copper-based binder), as known in the art. Such subterranean drill bits are typically used for rock drilling and for other operations which require high abrasion resistance or wear resistance. Generally, a rotary drill bit may include a plurality of polycrystalline abrasive cutting elements affixed to the drill bit body.
A PDC is normally fabricated by placing a cemented carbide substrate into a container or cartridge with a layer of diamond crystals or grains positioned adjacent one surface of a substrate. A number of such cartridges may be typically loaded into an ultra-high pressure press. The substrates and adjacent diamond crystal layers are then sintered under ultra-high temperature and ultra-high pressure conditions. The ultra-high pressure and ultra-high temperature conditions cause the diamond crystals or grains to bond to one another to form polycrystalline diamond. In addition, as known in the art, a catalyst may be employed for facilitating formation of polycrystalline diamond. In one example, a so-called “solvent catalyst” may be employed for facilitating the formation of polycrystalline diamond. For example, cobalt, nickel, and iron are among examples of solvent catalysts for forming polycrystalline diamond. In one configuration, during sintering, solvent catalyst comprising the substrate body (e.g., cobalt from a cobalt-cemented tungsten carbide substrate) becomes liquid and sweeps from the region adjacent to the diamond powder and into the diamond grains. Of course, a solvent catalyst may be mixed with the diamond powder prior to sintering, if desired. Also, as known in the art, such a solvent catalyst may dissolve carbon. Such carbon may be dissolved from the diamond grains or portions of the diamond grains that graphitize due to the high temperatures of sintering. The solubility of the stable diamond phase in the solvent catalyst is lower than that of the metastable graphite under high-pressure, high temperature (“HPHT”) conditions. As a result of this solubility difference, the undersaturated graphite tends to dissolve into solution; and the supersaturated diamond tends to deposit onto existing nuclei to form diamond-to-diamond bonds. Thus, diamond grains become mutually bonded to form a polycrystalline diamond table upon the substrate. The solvent catalyst may remain in the polycrystalline diamond layer within the interstitial pores between the diamond grains or the solvent catalyst may be at least partially removed from the polycrystalline diamond, as known in the art. For instance, the solvent catalyst may be at least partially removed from the polycrystalline diamond by acid leaching. A conventional processes for forming polycrystalline diamond cutters is disclosed in U.S. Pat. No. 3,745,623 to Wentorf, Jr. et al., the disclosure of which is incorporated herein, in its entirety, by this reference. Optionally, another material may replace the solvent catalyst that has been at least partially removed from the polycrystalline diamond.
One of ordinary skill in the art may appreciate that providing polycrystalline diamond, polycrystalline diamond compacts apparatuses, structures, or other articles of manufacture including polycrystalline diamond with improved properties and methods of manufacture may be advantageous.
One aspect of the instant disclosure relates to a method of manufacturing polycrystalline diamond. More particularly, a mixture may be provided, the mixture comprising: at least about 80% by weight diamond and fullerenes. Further, the mixture may be exposed to a pressure of at least about 60 kilobar and the mixture may be heated to a temperature of at least about 1350° Celsius. In another embodiment, the mixture may be exposed to a pressure of at least about 52 kilobar and the mixture may be heated to a temperature of at least about 1320° Celsius. In a further embodiment, the mixture may be exposed to a pressure of at least about 48 kilobar and the mixture may be heated to a temperature of at least about 1160° Celsius. For example, such a process may be used in combination with a non-cobalt catalyst, such as INVAR®.
Another aspect of the present invention relates to an article of manufacture. Specifically, an article of manufacture may comprise a volume of polycrystalline diamond bonded to a substrate (e.g., a compact, a cutting element, a wire die, a heat sink, a wear element, etc.). In addition, the volume of polycrystalline diamond may be formed by providing a mixture comprising at least about 80% by weight diamond and fullerenes, exposing the mixture to a pressure of at least about 60 kilobar, and heating the mixture to a temperature of at least about 1350° Celsius. In another embodiment, the mixture may be exposed to a pressure of at least about 52 kilobar and the mixture may be heated to a temperature of at least about 1320° Celsius. In a further embodiment, the mixture may be exposed to a pressure of at least about 48 kilobar and the mixture may be heated to a temperature of at least about 1160° Celsius. For example, such a process may be used in combination with a non-cobalt catalyst, such as INVAR®.
A further aspect of the present invention relates to a drill bit for drilling a subterranean formation. Such a drill bit may include a bit body comprising a leading end having generally radially extending blades structured to facilitate drilling of a subterranean formation. Further, the drill bit may include at least one cutting element comprising a substrate including a volume of polycrystalline diamond bonded to the substrate on an end surface of the substrate. Additionally, the volume of polycrystalline diamond may be formed by providing a mixture comprising at least 80% by weight diamond and fullerenes, exposing the mixture to a pressure of at least about 60 kilobar, and exposing the mixture to a temperature exceeding 1350° Celsius. In another embodiment, the mixture may be exposed to a pressure of at least about 52 kilobar and the mixture may be heated to a temperature of at least about 1320° Celsius. In a further embodiment, the mixture may be exposed to a pressure of at least about 48 kilobar and the mixture may be heated to a temperature of at least about 1160° Celsius. For example, such a process may be used in combination with a non-cobalt catalyst, such as INVAR®.
In addition, one aspect of the present invention relates to a polycrystalline diamond compact comprising a volume of polycrystalline diamond bonded to a substrate; wherein the polycrystalline diamond includes less than about 1% by weight carbon in a non-fullerenes, non-diamond form. A further aspect of the present invention relates to a polycrystalline diamond compact comprising a volume of polycrystalline diamond bonded to a substrate wherein the polycrystalline diamond is substantially free of non-fullerenes, non-diamond carbon.
A further aspect of the present invention relates to polycrystalline diamond exhibiting a relatively high diamond volume fraction. In one embodiment, such polycrystalline diamond may form a polycrystalline diamond compact. The present invention contemplates that such polycrystalline diamond may exhibit an increased diamond volume fraction due to the presence of fullerenes during manufacture relative to polycrystalline diamond formed without fullerenes. In one embodiment, a polycrystalline diamond compact may comprise a volume of polycrystalline diamond bonded to a substrate, wherein the volume of polycrystalline diamond exhibits a diamond volume fraction exceeding about 90% due to the presence of fullerenes during manufacture of the volume of polycrystalline diamond.
Features from any of the above-mentioned embodiments may be used in combination with one another, without limitation. In addition, other features and advantages of the instant disclosure will become apparent to those of ordinary skill in the art through consideration of the ensuing description, the accompanying drawings, and the appended claims.
Further features of the subject matter of the instant disclosure, its nature, and various advantages will be more apparent from the following detailed description and the accompanying drawings, which illustrate various exemplary embodiments, are representations, and are not necessarily drawn to scale, wherein:
The present invention relates generally to structures comprising polycrystalline diamond and methods of manufacturing such structures. As described above, during sintering, small diamond particles or grains (i.e., diamond powder) are caused to bond together to form a larger, substantially coherent structure.
As described above, manufacturing polycrystalline diamond involves the compression of diamond particles under extremely high pressure. Such compression may occur at room temperature, at least initially, and may result in the reduction of void space in the diamond powder (e.g., due to brittle crushing, sliding, and/or stacking of diamond particles). Of course, diamond particles are very hard and may not pulverize easily. Thus, the diamond particles may sustain very high local pressures where they come in contact with each other, but the pressures experienced on noncontacting surfaces of the diamond particles and in the interstitial voids may be relatively low. Manufacturing polycrystalline diamond further involves heating the diamond powder during compression of the diamond powder. Such heating may increase the temperature of the diamond powder from room temperature at least to the melting point of a solvent catalyst. At elevated temperature, regions of the diamond powder that are not under high local pressure may graphitize. As a solvent-catalyst melts, it may infiltrate or “sweep” through the diamond particles. In addition, as known in the art, a solvent catalyst (e.g., cobalt, nickel, iron, etc.) may dissolve and transport carbon between the diamond grains and facilitate diamond formation. Particularly, the presence of a solvent catalyst may facilitate formation of diamond-to-diamond bonds comprising polycrystalline diamond and resulting in a coherent skeleton of diamond.
The present invention generally contemplates that a mixture may comprise diamond and fullerenes and may be exposed to a high-pressure, high-temperature (HPHT) sintering process to form polycrystalline diamond. Such a method may enhance graphite-to-diamond conversion, diamond formation, or bonding of the diamond particles during HPHT sintering of diamond powder. The term “fullerenes,” as used herein, refers to any polygonal form of carbon. One common form of fullerenes comprises 60 carbon atoms arranged in a geodesic dome structure. Such a carbon structure is termed a “Buckminsterfullerene” or “fullerene,” although such structures are also sometimes referred to as “buckyballs.” Fullerenes are commonly denoted as Cn fullerenes (e.g., n=24, 28, 32, 36, 50, 60, 70, 76, 84, 90, or 94) with “n” corresponding to the number of carbon atoms in the “complete” fullerenes structure. Further, elongated fullerenes structures can contain millions of carbon atoms, forming a hollow tube-like structure just a few atoms in circumference. These fullerenes structures are commonly known as carbon “nanotubes” or “buckytubes” and may have single or multi-walled structures. Any portion of such dome structures or tubes (i.e., any polygonal form of carbon) is encompassed by the term “fullerenes.”
Thus, generally, the present invention contemplates that a mixture may be provided comprising diamond and fullerenes. Further, such a mixture may be exposed to a pressure of at least about 60 kilobar and may be heated to a temperature of at least about 1350° Celsius (i.e., HPHT sintered). For example, such a process may be used with a catalyst such as cobalt. Such a method 100 is schematically shown in
In addition, many variations in the weight percentage of diamond as well as the weight percentage of fullerenes may be employed in a process for forming polycrystalline diamond. For example, as shown in the method 100 illustrated in
In another embodiment, an overall fullerenes concentration may be between about 0.01% by weight and about 0.30% by weight. For example, as shown in the method 100 illustrated in
As may be appreciated by one of ordinary skill in the art, it may be beneficial for fullerenes to be relatively pure. Such purity may limit contaminants, non-fullerenes carbon content of the mixture, or both. For example, fullerenes may be at least 99% pure (e.g., 99.5% pure). As a further aspect of the present invention, limiting a non-fullerenes, non-diamond carbon content of the mixture to be HPHT sintered (i.e., process actions 110 and 112) may be beneficial. For example, a non-fullerenes, non-diamond carbon content of the mixture may be less than about 0.003% by weight of the mixture (i.e., less than 1% of a 0.3% by weight fullerenes concentration). In another example, a non-fullerenes, non-diamond carbon content of the mixture may be less than about 0.0001% by weight of the mixture (i.e., less than 1% of 0.01% by weight fullerenes concentration).
In a further embodiment, the present invention contemplates that a mixture comprising C60 fullerenes and diamond may be exposed to a HPHT sintering process.
Any mixture of one or more Cn fullerenes (e.g., n=24, 28, 32, 36, 50, 60, 70, 76, 84, 90, and 94) may comprise a mixture that is HPHT sintered (i.e., process actions 110 and 112) to form polycrystalline diamond. For example, in another embodiment, as shown in the method 100 illustrated in
In a further embodiment, a mixture may be provided comprising fullerenes containing soot and diamond.
It should be understood that polycrystalline diamond is utilized in many applications. For instance, wire dies, bearings, artificial joints, inserts, cutting elements, and heat sinks may include polycrystalline diamond. Thus, the present invention contemplates that any of the methods encompassed by the above-discussion related to forming polycrystalline diamond may be employed for forming an article of manufacture comprising polycrystalline diamond. Generally, the present invention contemplates that a volume of polycrystalline diamond may be formed upon a substrate.
In one example of an article of manufacture comprising polycrystalline diamond, the present invention contemplates that any process encompassed by the above discussion may be employed for forming polycrystalline diamond compacts. Generally, polycrystalline diamond compacts are manufactured by positioning a mixture comprising diamond adjacent to a substrate (e.g., a cobalt-cemented tungsten carbide substrate) and subjecting the mixture and substrate to a HPHT sintering process. Thus, a polycrystalline diamond layer or table (i.e., a volume of polycrystalline diamond) may be formed upon the substrate. As known in the art, a polycrystalline diamond compact may be used as a cutting element or a bearing element, as discussed in further detail below.
Thus, the present invention contemplates that a mixture may be provided comprising diamond and fullerenes for forming a polycrystalline diamond cutting element. Such a mixture may be positioned adjacent to a substrate, such as, for instance, a cobalt-cemented tungsten carbide substrate. In other embodiments, a substrate may comprise at least one of the following: titanium carbide, niobium carbide, tantalum carbide, vanadium carbide, iron, and nickel, without limitation. Further, the mixture and the substrate may be exposed to a pressure of at least about 60 kilobar and may be heated to a temperature of at least about 1350° Celsius (i.e., HPHT sintered). Such a method 201 is schematically shown in
Thus, the present invention contemplates that any apparatus as known in the art comprising polycrystalline diamond may include polycrystalline diamond formed (i.e., sintered) with fullerenes as described above. In one example, a rotor and a stator (i.e., a thrust bearing apparatus) may each comprise polycrystalline diamond and may be operably assembled to downhole drilling assembly, as known in the art. U.S. Pat. Nos. 4,410,054, 4,560,014, 5,364,192, 5,368,398, and 5,480,233, the disclosure of each of which is incorporated herein, in its entirety, by this reference, disclose exemplary subterranean drilling systems within which bearing apparatuses according to the present invention may be incorporated. Of course, polycrystalline diamond sintered with fullerenes may comprise heat sinks, wire dies, bearing elements, cutting elements, cutting inserts (e.g., on a roller cone type drill bit), machining inserts, or any other article of manufacture as known in the art. Other examples of articles of manufacture comprising polycrystalline diamond may be disclosed by, inter alia, U.S. Pat. Nos. 4,811,801, 4,274,900, 4,268,276, 4,468,138, 4,738,322, 4,913,247, 5,016,718, 5,092,687, 5,120,327, 5,135,061, 5,154,245, 5,460,233, 5,544,713, and 6,793,681, the disclosure of each of which is incorporated herein, in its entirety, by this reference.
As known in the art, during sintering, a catalyst material (e.g., cobalt, nickel, etc.) may be employed for facilitating formation of polycrystalline diamond. More particularly, as known in the art, diamond powder or material placed adjacent to a cobalt-cemented tungsten carbide substrate and subjected to a HPHT sintering process may wick or sweep molten cobalt into the diamond. Such cobalt may remain in the polycrystalline diamond table upon sintering and cooling. In other embodiments, catalyst may be provided within the diamond material, as a layer of material between the substrate and diamond, or as otherwise known in the art. As also known in the art, such a catalyst material may be at least partially removed (e.g., by acid-leaching or as otherwise known in the art) from at least a portion of the volume of polycrystalline diamond (e.g., a table) formed upon the substrate. Catalyst removal may be substantially complete to a selected depth from an exterior surface of the polycrystalline diamond table, if desired, without limitation. As known in the art, such catalyst removal may provide a polycrystalline diamond material with increased thermal stability, which may also beneficially affect the wear resistance of the polycrystalline diamond material.
The present invention contemplates that mixture 10 as shown in
Further, the inventors of the present invention have discovered that increases in wear resistance of polycrystalline diamond cutting elements may result from including fullerenes with diamond to form polycrystalline diamond cutting elements or compacts. Particularly, laboratory tests indicate that polycrystalline diamond cutting elements manufactured with fullerenes exhibit increased wear resistance and thermal stability in comparison to conventionally manufactured polycrystalline diamond cutting elements. More specifically, diamond having a nominal size of about 20 microns was mixed with various concentrations of 99.5% pure C60 fullerenes to produce three cutting elements. Such C60 fullerenes material may be commercially available from, for example, MER Corporation, of Tucson, Ariz. Generally, the diamond and C60 fullerenes mixture was placed adjacent to a cemented tungsten carbide substrate and loaded into a niobium vessel. One polycrystalline diamond cutting element was manufactured without any fullerenes. The niobium vessel was subjected to a pressure of at least about 60 kbar and a temperature of about 1400° C. for about 5 minutes. All four of the polycrystalline diamond cutting element cutters referenced in Table 1 were sintered in the same HPHT process. The polycrystalline diamond cutting elements manufactured according to this sintering process were subsequently used to machine Sierra White granite both with and without added coolant. The results of these experimental tests are summarized in Table 1, shown below.
Additional laboratory tests for three polycrystalline diamond cutting elements cutters that were manufactured during another HPHT cycle were performed. More specifically, results of this experimental test are summarized in Table 2, shown below.
The above data may indicate relative wear resistance and thermal stability as a function of fullerenes weight percentage for the cutting elements included within each experimental group. More particularly, the overall distances cut without coolant (prior to failure of the cutting element) associated with cutting elements that were manufactured with various concentrations of C60 fullerenes are shown in the second columns of Tables 1 and 2. Also, the third columns of Tables 1 and 2 show wearflat volumes generated by cutting a given amount (about 400 in3) of Sierra White granite with cutting elements that were manufactured with various concentrations of C60 fullerenes.
Further,
Generally, a distance cut by a cutting element without coolant may indicate a thermal stability of the cutting elements. In addition, a wearflat volumes (i.e., amount of diamond worn from the diamond table during cutting) generated with coolant (for a given or selected volume of material cut) may relate to a wear resistance of a cutting element. Explaining further, a relatively longer distance cut without coolant may indicate a relatively high thermal stability. In addition, a relatively small wearflat volume may indicate a relatively high wear resistance. As shown in
As noted above, polycrystalline diamond cutting compacts that are formed by the processes discussed above may exhibit wear resistance and thermal stability that exceed conventionally manufactured polycrystalline diamond cutting elements. Thus, the experimental results discussed above may indicate that polycrystalline diamond that is formed according to the processes of present invention is structurally different from polycrystalline diamond that is formed conventionally. For example, employing fullerenes in a sintering process comprising pressure of at least about 60 kilobar and temperature of at least about 1350° Celsius may result in increased diamond-to-diamond bonding or overall diamond formation in comparison to polycrystalline diamond formed by conventional processes.
Further, polycrystalline diamond formed by the methods described above may exhibit structural differences in comparison to conventionally manufactured polycrystalline diamond. For example, one of ordinary skill in the art may appreciate that, subsequent to HPHT sintering, at least some fullerenes may remain within the polycrystalline diamond. Thus, the nature of any remaining fullerenes within the polycrystalline diamond may be structurally distinguishable and detectable in comparison to nondiamond carbon, if any, that may be present within a conventionally formed polycrystalline diamond.
As a further structural characteristic, polycrystalline diamond formed by the above-described methods may include a relatively small amount of non-fullerenes (and non-diamond) carbon. In one example, a non-fullerenes, non-diamond carbon content of polycrystalline diamond formed by any of the above-referenced methods (or variants thereof) may be less than about 1% by weight of the polycrystalline diamond. In another example, a non-fullerenes, non-diamond carbon content of polycrystalline diamond formed by any of the above-referenced methods (or variants thereof) may be less than about 0.003% by weight of the polycrystalline diamond. In another example, a non-fullerenes, non-diamond carbon content of the polycrystalline diamond may be less than about 0.0001% by weight of the polycrystalline diamond. In a further embodiment, polycrystalline diamond may be substantially free of a non-fullerenes, non-diamond carbon. Of course, other unique structural aspects of polycrystalline diamond formed with fullerenes may be detectable and may indicate the temperature and pressure of the HPHT sintering process employed to form the polycrystalline diamond.
As a further structural aspect of polycrystalline diamond formed by any of the methods described above, such polycrystalline diamond may exhibit a relatively high diamond volume fraction (i.e., a diamond density). More specifically, results of experimentally-determined diamond volume fractions relating to polycrystalline diamond formed with varying fullerenes concentrations are summarized in Table 3, shown below.
In general, as shown in Table 3, polycrystalline diamond formed without fullerenes may exhibit a diamond volume fraction of about 89.33%. Relative to the data shown in Table 3, a diamond powder having a nominal size of about 20 μm was employed for forming the polycrystalline diamond. As shown in Table 3, each fullerenes weight percentage correlates with a diamond volume fraction exceeding about 90%. In one embodiment, the present invention contemplates that polycrystalline diamond formed with fullerenes or including fullerenes may exhibit a diamond volume fraction that exceeds 90%. In addition, the present invention contemplates that, in a different embodiment, polycrystalline diamond formed with fullerenes may exhibit a diamond volume fraction that exceeds about 90.5%. In another embodiment, the present invention contemplates that polycrystalline diamond formed with fullerenes may exhibit a diamond volume fraction that exceeds about 90.6%. In a further embodiment, the present invention contemplates that polycrystalline diamond formed with fullerenes may exhibit a diamond volume fraction that is about 90.7% or exceeds about 90.7%. Of course, a polycrystalline diamond compact (i.e., a polycrystalline diamond volume bonded to a substrate) may comprise polycrystalline diamond exhibiting a relatively high diamond volume fraction. One of ordinary skill in the art will appreciate that diamond volume fraction may be influenced by, among other considerations, pressures and temperatures of a HPHT sintering process, catalyst composition, and initial diamond powder grain size. Accordingly, in general, the present invention contemplates that a volume of polycrystalline diamond may exhibit an increased diamond volume fraction due to the presence of fullerenes during manufacture relative to polycrystalline diamond formed without fullerenes. Thus, given substantially identical (within controllable parameters) HPHT processes and material compositions, polycrystalline diamond formed in the presence of fullerenes may exhibit a higher diamond volume fraction relative to polycrystalline diamond formed without fullerenes.
As may be appreciated from the foregoing discussion, the present invention further contemplates that at least one cutting element manufactured according to the above-described processes may be coupled to a rotary drill bit. Such a configuration may provide a cutting element with enhanced wear resistance in comparison to a conventionally formed cutting element. For example,
It should be understood that although rotary drill bit 301 includes cutting element 340 and 342 the present invention is not limited by such an example. Rather, a rotary drill bit according to the present invention may include, without limitation, one or more cutting elements according to the present invention. Optionally, all of the cutting elements (i.e., 340, 342, and 308) shown in
While certain embodiments and details have been included herein and in the attached invention disclosure for purposes of illustrating the invention, it will be apparent to those skilled in the art that various changes in the methods and apparatus disclosed herein may be made without departing form the scope of the invention, which is defined in the appended claims. The words “including” and “having,” as used herein, including the claims, shall have the same meaning as the word “comprising.”
This application is a divisional of U.S. patent application Ser. No. 11/351,564, filed Feb. 10, 2006, now U.S. Pat. No. 7,841,428, the disclosure of which is incorporated, in its entirety, by reference.
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| Number | Date | Country | |
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| Child | 12909716 | US |
