A PDC cutter and method of making it

Abstract

A superabrasive compact and a method of making the superabrasive compact are disclosed. A superabrasive compact may comprise a diamond body and a metallic substrate. The diamond body comprises a first phase comprising a binderless intercrystalline diamond- to-diamond bonded matrix extending throughout the diamond body; and a second phase comprising a binder / catalyst within interstitial regions of intercrystalline bonded diamond matrix. The first phase is substantially free of the binder / catalyst material. The metallic substrate is in direct contact with the diamond body. The diamond body includes a first region comprising the catalyst / binder material and a second region is substantially free of the binder / catalyst. The second region may be positioned along a wear surface of the supcrabrasivc compact.

Description

[0001] A PDC CUTTER AND METHOD OF MAKING IT

[0002] CROSS-REFERENCE AND PRIORITY CLAIM TO RELATED PATENT APPLICATIONS

[0003] This patent application claims priority of U.S. application Ser. No. 18 / 535,587, entitled “A PDC CUTTER AND METHOD OF MAKING IT”, filed Dec. 1 1 , 2023, the entire disclosures of each of which are incorporated herein by reference.

[0004] TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY

[0005] The present invention relates generally to superabrasive materials and a method of making superabrasive materials, and more particularly, to polycrystalline diamond compacts (PCD) made using binderless diamond to manufacture a PDC cutter.

[0006] BACKGROUND OF THE INVENTION

[0007] Polycrystalline diamond (PCD) materials and PDC elements formed therefrom are well known in the art. Conventionally, PDC is formed by combining diamond grains with a suitable binder / catalyst material. The mixture is subjected to conditions of extremely high temperature / high pressure, where the binder / catalyst material promotes desired intercrystalline diamond-to-diamond bonding between the grains, thereby forming a polycrys tailine diamond structure. The resulting PDC structure produces enhanced properties of wear resistance and hardness, making PDC materials extremely useful in aggressive wear and cutting applications where high levels of wear resistance and hardness are desired. Binder / catalyst materials that are typically used for forming PDC include Group VIII elements, cobalt (Co) being the most common. Conventional PDC can comprise from 85 to 95% by volume diamond and a remaining amount of the binder / catalyst material. The binder / catalyst material is present in the PDC material within interstices that exist between the bonded together diamond grains.

[0008] One problem known to exist with such conventional PDC materials is thermal degradation due to differential thermal expansion between the interstitial cobalt binder / catalyst material and the intercrystalline bonded diamond. This is known to occur at temperatures of about 400° C. Upon sufficient expansion, the diamond-to-diamond bonding may be ruptured and cracks and chips may occur.

[0009] Another problem known to exist with convention PDC materials involves the presence of the binder / catalyst material in the interstitial regions adhering to the diamond crystals, and another form of thermal degradation. This presence of the binder / catalyst material is known to catalyze phase transformations in diamond (converting to carbon monoxide, carbon dioxide, or graphite) with increasing temperature, thereby limiting practical use of the PDC material to about 750° C.

[0010] Attempts at addressing this issue are known in the art. Generally, these attempts have involved the formation of a PDC material having an improved degree of thermal stability when compared to the conventional PDC material discussed above. One known technique of producing a thermally stable PDC material involves a multi-step process of first forming a conventional sintered PDC element, i.e., one formed by combining diamond grains and a cobalt binder / catalyst material at high temperature / high pressure, and secondly selectively removing the binder / catalyst material from a working surface of the sintered element.

[0011] While this multi-step process results in the removal of the binder / catalyst from a select portion of the PDC element working surface, and is promoted as providing improved thermal stability in the region of the element where the binder / catalyst has been removed, it involves a multi-step process that is both time consuming and labor intensive.

[0012] It is, therefore, desired that a PDC material be developed that has improved thermal stability when compared to conventional PDC materials.

[0013] SUMMARY

[0014] In one embodiment, a superabrasive compact may comprise a diamond body and a metallic substrate. The diamond body comprises a first phase comprising a binderless intercrystalline diamond-to-diamond bonded matrix extending throughout the diamond body; and a second phase comprising a binder / catalyst within interstitial regions of intercrystalline bonded diamond matrix. The first phase is substantially free of the binder / catalyst material. The metallic substrate is in direct contact with the diamond body. The diamond body includes a first region comprising the catalyst / binder material and a second region is substantially free of the binder / catalyst. The second region may be positioned along a wear surface of the superabrasive compact.

[0015] Optionally in any embodiment, the binder / catalyst material comprises cobalt.

[0016] Optionally in any embodiment, the second region is substantially free of porosity.

[0017] Optionally in any embodiment, the metallic substrate comprise a metal carbide.

[0018] Optionally in any embodiment, the second region is substantially free of metal.

[0019] Optionally in any embodiment, the metal comprises catalyst.

[0020] Optionally in any embodiment, the catalyst comprises cobalt.

[0021] Optionally in any embodiment, the metal carbide comprises tungsten carbide.

[0022] Optionally in any embodiment, the second region of the diamond body extends to a depth of at least about 0.1 mm from the wear surface.

[0023] Optionally in any embodiment, the first region of the diamond body has an average thickness greater than about 0.15 mm.

[0024] Optionally in any embodiment, an amount of catalyst / binder material within the first region of the body continuously increases with distance from the second region.

[0025] In another embodiment, a superabrasive compact may comprise a diamond body. The diamond body may comprise a first region and a second region. The first region may comprise a catalyst / binder material and a second region is substantially free of the binder / catalyst. The second region may be positioned along a wear surface of the superabrasive compact. The second region comprises a binderless polycrystalline diamond material. The second region is substantially free of porosity.

[0026] Optionally in any embodiment, the diamond body may comprise a first phase and a second phase. The first phase may comprise a binderless intercrystalline diamond-to-diamond bonded matrix extending throughout the diamond body. The second phase may comprise a binder / catalyst within interstitial regions of intercrystalline bonded diamond matrix.

[0027] In yet another embodiment, a superabrasive compact may comprise a diamond body and a metallic substrate. The diamond body comprises a first phase and a second phase. The first phase may comprise a bindcrlcss intercrystalline diamond-to-diamond bonded matrix extending throughout the diamond body. The second phase may comprise a binder / catalyst within interstitial regions of intercrystalline bonded diamond matrix. The metallic substrate is in direct contact with the diamond body. The diamond body includes a first region and a second region. The second region is positioned along a wear surface of the superabrasive compact. The second region is substantially free of porosity and has substantially binderless intercrystalline diamond- to-diamond bonded matrix from the wearing surface.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The foregoing summary, as well as the following detailed description of the embodiments, will be better understood when read in conjunction with the appended drawings. It should be understood that the embodiments depicted are not limited to the precise arrangements and instrumentalities shown.

[0030] FIG. 1 is a schematic view of a polycrystalline diamond compact produced in an ultra-high pressure high temperature (HPHT) process according to an embodiment; FIG. 2 is a schematic perspective view of a cylindrical shape thermally stable polycrystalline diamond compact produced in an ultra-high pressure high temperature (HPHT) process according to another embodiment;

[0031] FIG. 3 is a schematic view of an assembly cup loading a plurality of diamonds with a carbide substrate according to one embodiment; and

[0032] FIG. 4 is a schematic view of an assembly cup loading a plurality of diamonds (or solid binderless diamond) with a carbide substrate according to one embodiment.

[0033] DETAILED DESCRIPTION

[0034] Before the description of the embodiment, terminology, methodology, systems, and materials are described; it is to be understood that this disclosure is not limited to the particular terminologies, methodologies, systems, and materials described, as these may vary. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions of embodiments only, and is not intended to limit the scope of embodiments. For example, as used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. In addition, the word “comprising” as used herein is intended to mean “including but not limited to.” Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.

[0035] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as size, weight, reaction conditions and so forth used in the specification and claims are to the understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0036] As used herein, the term “about” means plus or minus 10% of the numerical value of the number with which it is being used. Therefore, about 50% means in the range of 45%-55%.

[0037] As used herein, the term “superabrasive particles” may refer to ultra-hard particles or superabrasive particles having a Knoop hardness of 3500 KHN or greater. The superabrasive particles may include diamond and cubic boron nitride, for example. The term “abrasive”, as used herein, refers to any material used to wear' away softer materials.

[0038] The term “particle” or “particles”, as used herein, refers to a discrete body or bodies. A particle is also considered a crystal or a grain.

[0039] The term “superabrasive compact”, as used herein, refers to a sintered product made using super abrasive particles, such as diamond feed or cubic boron nitride particles. The compact may include a support, such as a tungsten carbide support, or may not include a support. The “superabrasive compact” is a broad term, which may include cutting element, cutters, or polycrystalline cubic boron nitride insert.

[0040] The term “cutting element”, as used herein, means and includes any element of an earthboring tool that is used to cut or otherwise disintegrate formation material when the earth-boring tool is used to form or enlarge a bore in the formation. The term “non-catalytic binder” material, as used herein, may refer to any material, metallic elements, non-metal, or semi-conductor materials, which do not involve or help tungsten carbide substrate chemical formation.

[0041] The term “feed” or “diamond feed”, as used herein, refers to any type of diamond particles, or diamond powder, used as a starting material in further synthesis of PDC compacts.

[0042] The term “polycrystalline diamond”, as used herein, refers to a plurality of randomly oriented or highly oriented monocrystalline diamond particles, which may represent a body or a particle consisting of a large number of smaller monocrystalline diamond particles of any sizes. Polycrystalline diamond particles usually do not have cleavage planes.

[0043] The term “supcrabrasivc”, as used herein, refers to an abrasive possessing superior hardness and abrasion resistance. Diamond and cubic boron nitride are examples of superabrasives and have Knoop indentation hardness values of over 3500.

[0044] The terms “diamond particle” or “particles” or “diamond powder”, which is a plurality of a large number of single crystal or polycrystalline diamond particles, are used synonymously in the instant application and have the same meaning as “particle” defined above.

[0045] Polycrystalline diamond compact (or “PCD”, as used hereinafter) may represent a volume of crystalline diamond grains with embedded foreign material filling the inter-grain space. In one particular case, a superabrasive compact comprises crystalline diamond grains, bound to each other by strong diamond-to-diamond bonds and form a rigid polycrystalline diamond body, and the inter-grain regions, disposed between the bounded grains and filled in one part with a catalyst material (e.g. cobalt or its alloys), which was used to promote diamond bonding during fabrication, and other part may be filled with other materials which may remain after the sintering of diamond compact. Suitable metal solvent catalysts may include the iron group transitional metal in Group VIII of the Periodic table.

[0046] “Thermally stable polycrystalline diamond” as used herein is understood to refer to intercrystalline bonded diamond that includes a volume or region that is or that has been rendered substantially free of the solvent metal catalyst or binder used to form PCD, or the solvent metal catalyst or binder used to form PDC remains in the region of the diamond body but is otherwise reacted or otherwise rendered ineffective in its ability adversely impact the bonded diamond at elevated temperatures as discussed above.

[0047] Polycrystalline diamond compacts (or PDC compacts) may be fabricated in different ways and the examples discussed herein do not limit a variety of different types of diamond composites and PDC compacts which may be produced according to an embodiment.

[0048] PDC materials of this invention and PDC compacts formed therefrom are specially engineered to provide improved thermal stability when compared to conventional PDC materials and are, therefore, referred to as thermally- stable PCD.

[0049] Thermally stable PDC materials of this invention disclosure may be formed during a single process step of consolidating and sintering the PDC material. During this single ultra high pressure high temperature (UHPHT) processing step, the diamond particles are sintered without binder / catalyst material that is used to catalyze diamond-to-diamond intercrystalline bonding to form binderless polycrystalline diamond compacts. This resulting compact has a degree of thermal stability that is greater than that with the binder / catalyst material, thereby contributing to the formation of a PDC element, e.g., a compact, having improved overall thermal stability when compared to conventional PCD. FIG. 1 illustrates a superabrasive compact 10 of this invention having a material microstructure comprising at least two material phases. A first phase 12 comprises a binderless intercrystalline diamond-to-diamond bonded matrix extending throughout the diamond body, and a second phase 14 disposed inters titially between the diamond comprises a binder / catalyst within interstitial regions of intercrystalline bonded diamond matrix. In one embodiment, the binder / catalyst material may comprise cobalt. In one embodiment, the first phase is substantially free of the binder / catalyst material.

[0050] A superabrasive compact 10 in accordance with an embodiment is shown in FIG. 2. Superabrasive compact 10 may be inserted into a downhole of a suitable tool, such as a drill bit, for example. One example of the supcrabrasivc compact 10 may include a diamond table 25 having a top surface 21.

[0051] In one embodiment, the superabrasive compact 10 may be a standalone compact without a substrate. In another embodiment, the superabrasive compact 10 may include a metallic substrate 20 attached to the superabrasive diamond body 25 formed by a plurality of polycrystalline diamond particles.

[0052] The metallic substrate 20 may be a metal carbide, attached to the superabrasive diamond body 25 via an interface 22 separating the superabrasive diamond table 25 and the metallic substrate 20. The metal carbide may comprise tungsten carbide, for example. The interface 22 may have an uneven interface. Substrates useful for forming PDC compacts of this invention can be selected from the same general types of conventional materials used to form substrates for conventional PDC materials, including carbides, nitrides, carbonitrides, cermet materials, and mixtures thereof. In an exemplary embodiment, the substrate can be formed from cemented tungsten carbide (WC-Co). Metallic substrate 20 may be made from hard metal carbides and a binder having carbon at least partially dissolved therein. In one embodiment, the metallic substrate 20 may be cemented cobalt tungsten carbide, while the superabrasive diamond body 25 may be formed from a polycrystalline ultra-hard material, such as polycrystalline diamond or diamond crystals bonded by itself or by a foreign material.

[0053] Still in FIG. 2, the superabrasive diamond body 25 may include at least two regions with a first region 24 and a second region 26. The first region 24 may be closer to the interface 22 and may be sandwiched between the metallic substrate 20 and the second region 26.

[0054] In one embodiment, the first region 24 may comprise the catalyst / binder material. The second region 26 may be substantially free of the bindcr / catalyst and may be positioned along a weai' surface or the top surface 21 of the superabrasive compact 10.

[0055] The second region 26 may be binderless polycrystalline diamond material. The binderless polycrystalline diamond material may have a final plurality of diamonds with an average particle size of greater than about 1 micronmeter diameter, for example. In one embodiment, the second region of the diamond body extends to a depth (D) of at least about 0.1 mm, for example, from the wear surface.

[0056] In one embodiment, the first region of the diamond body has an average thickness greater than about 0.15 mm.

[0057] Due to high pressure high temperature (HPHT) or ultra high pressure high temperature (UHPHT), the catalyst / binder cobalt may sweep from the metallic substrate to the diamond body, which may cause an amount of catalyst / binder material within the first region of the body continuously increases with distance from the second region. The superabrasive compact 10 may be referred to as a polycrystalline diamond compact (“PCD”) when polycrystalline diamond is used to form the superabrasive diamond body 25. PDC compacts are known for their toughness and durability, which allow them to be an effective cutter in demanding applications. Although one type of superabrasive compact 10 has been described, other types of superabrasive compacts 10 may be utilized. For example, in one embodiment, superabrasive compact 10 may have a chamfer (not shown) around an outer peripheral of the top surface 21. The chamfer may have a vertical height of about 0.5 mm or 1 mm, for example, and an angle of about 45° degrees, for example, which may provide a particularly strong and fracture resistant tool component.

[0058] As shown a prc-sintcrcd cup assembly 30 in FIG. 3, a metal cup 38 (Ta or Nb, for example) may be used to load a first portion 36 containing carbons or graphite or modified diamond particles without catalytic materials. A high frequency vibrator may be used to level this portion 36. Then, a second portion 34 containing diamond particles may be carefully loaded on top of the first portion 36. Again a high frequency vibrator is used to level the second portion 34 as the diamond bed. This portion can be just a pure diamond feed. A cemented tungsten carbide substrate 32 is inserted into the cup 38. Its interface touches the diamond bed directly. Subsequently, a load of lOOKg, for example, is applied to densify the loaded materials. The loaded cup is further assembled using HPHT cell components and is subjected to the cubic press for UHPHT sintering process under 16GPa and 2300 C. The sintered piece is further ground and machined to the final size of the PDC product as illustrated in the FIG. 2 suitable binder / catalyst materials useful for forming thermally stable PDC materials of this invention include those metals selected from Group VIII elements of the Periodic table, a particularly preferred binder / catalyst material being cobalt. Alternatively, the second portion (34) may be mixed with catalytic materials such as cobalt, iron or nickel alloy in about 0.1-20 weight percent PDC materials, which is prepared by combining synthetic diamond powder having an average diameter grain size in the range of from submicrometer in size to 100 micrometers, and more preferably in the range of from about 20 to 80 micrometers, with or without cobalt powder to provide a cobalt coating thereon. The diamond powder can contain grains having a mono or multi modal size distribution. In an exemplary embodiment, the cobalt powder has an average grain size in the range of from about submicrometer to tens of micrometers, and more preferably in the range of about 0.1 to about 10 micrometers.

[0059] Another method of achieving a coating of cobalt on the diamond particles would be to coat them with a thin layer of Cobalt by some means known to the ail. Various methods could be used to achieve this such as sputter coating, physical vapor deposition, chemical vapor deposition, decomposition of organo-metallic complexes, electrolytic plating, and the like. It is understood that methods not specifically listed above may be used to obtain a coating on the diamond grains.

[0060] In an exemplary embodiment, the mixture of diamond and cobalt powder comprises in the range of from 80 to 99 percent by volume diamond, and a remaining amount cobalt, based on the total volume of the mixture. The diamond grains and cobalt powder arc combined together by conventional process, such as by ball or attritor milling for as much time as necessary to ensure good cobalt over diamond grain coverage. It is understood that during this process step some of the diamond grains may not be entirely coated with the binder / catalyst material.

[0061] Alternatively, still in FIG. 3, a metal cup 38 (Ta or Nb) may be used to load the first portion 36 containing carbons or graphite or modified diamond particles without catalytic materials. A high frequency vibrator is used to level this portion 36. Then, a second portion 34 may be loaded containing diamond particles on top of the first portion 36. Again a high frequency vibrator may be used to level the second portion 34 as the diamond bed. This portion 34 is premixed with non-catalytic materials, such as Boron, Be, Al, Mo, Nb, Ta, V, Zr. Si, Ti, CaCCh. and MgCCh powders in a 0.1-20 weight percent. A cemented tungsten carbide substrate 32 is inserted into the cup. Its interface touches the diamond bed directly. Subsequently, a load of lOOKg is applied to densify the loaded materials. The loaded cup is further assembled using HPHT cell components and is subjected to the cubic press for HPHT sintering process under 16GPa and 2300 C. The sintered piece is further ground and machined to the final size of the PDC product as illustrated in the FIG.2.

[0062] A non-catalytic material or getter material is combined with the diamond grains, and the mixture is blended together by conventional method such as by ball or attritor milling for as long as necessary to obtain good getter material coverage over or with the diamonds. Suitable getter materials useful for forming thermally stable PDC materials of this invention include those that are capable of reacting with the binder / catalyst material during the consolidation and sintering process, e.g., at a point of the consolidating and sintering process where intercrystalline diamond bonding has started to take place. Suitable getter materials include those that react with the binder / catalyst material to form a compound having a degree of thermal stability that is greater than that of the binder / catalyst material alone, thereby contributing to the overall thermal stability of the PDC material. In forming thermally stable PDC materials of this invention, one or a combination of getter materials can be used.

[0063] In an exemplary embodiment, where the binder / catalyst is cobalt, a desired getter material comprises silicon or a silicon-containing compound provided in the form of a powder. Preferred silicon or silicon-containing compounds include pure silicon (Si) and silicon carbide (SiC). These getter materials can be used alone or in combination. In a preferred embodiment, a combination of silicon and silicon carbide is used. When combined with the cobalt coated diamond grains, the resulting mixture comprises diamond grains that have a sequential coating of the binder / catalyst material and the getter material.

[0064] The resulting mixture is cleaned to enhance the sinterability of the powder by treatment at high temperature in a vacuum or reducing atmosphere. The blended powder mixture is loaded into a desired container for placement within a suitable high pressure / high temperature consolidation and sintering device. The device is then activated to subject the container to a desired high pressure / high temperature condition to effect consolidation and sintering. Thermally stable PDC materials of this invention can be consolidated and sintered by conventional equipment and techniques used to consolidate and sinter conventional PDC materials.

[0065] During the high pressure / high temperature consolidation and sintering process, the cobalt coating on the diamond grains is theorized to provide highly localized catalysis for the rapid creation of strong bonds between the diamond grains or crystals, i.e., producing intercrystalline bonded diamond. As these bonds are formed, the cobalt moves into interstitial regions between the intercrystalline bonded diamond where it combines and reacts with the getter material, in this case Si and / or SiC. The following reactions producing cobalt disilicide (CoSi2) are believed to occur:

[0066] Co+2Si - >CoSi2 Reaction I

[0067] Co+2SiC - >CoSi2+2C Reaction II

[0068] The formation of cobalt disilicide according to the above-noted reactions is a desired result because it is known to have a level of thermal stability that is superior to cobalt alone, thereby producing a PDC material having an overall corresponding improved degree of thermal stability. In the event that the getter material used is SiC, it is believed that the free carbon that is produced according to Reaction II precipitates as diamond since the reaction takes place during the high pressure / high temperature reaction in the diamond- stable region of the diamond phase diagram.

[0069] The formation and presence of this precipitated diamond in the binder phase of the PDC material microstructure is believed to have two advantages. First, it functions to enhance the overall wear and abrasion resistance of the PDC material. Second, it functions to both improve the thermal conductivity of the binder phase, and provide a coefficient of thermal expansion that is closely matched to the intercrystalline diamond bonded phase, thereby contributing to the overall thermal stability of the material.

[0070] The use of pure silicon (Si) as the getter material has the advantage that excess material, e.g., silicon, that has not reacted with cobalt is believed to form a reaction phase with the diamond crystals in the intercrystalline diamond bonded phase according to the reaction:

[0071] Si+C - >SiC Reaction III

[0072] This reaction between the pure silicon and the diamond crystals is desired as it is believed to improve bonding between the binder phase and the intercrystalline diamond phase, thereby providing a PDC material having an overall improved level of structural strength between the phases.

[0073] It is to be understood that the type and amount of getter material(s) that is used can and will vary depending on the particular type and amount of binder / catalyst material that is used, in addition to the particular application for the resulting PDC compact or element that is formed from the PDC material. Additionally, as noted above, the amount of the getter materials that are used, e.g., over the stoichiometric amount, can and will vary depending on the types of reactions products that are formed. For example, as noted above, it may be desired to use a stoichiometric excess of a particular getter material to produce, in addition to a desired reaction product having an improved level of thermal stability, a desired reaction product in the binder or getter material phase of the material construction. In an exemplary embodiment, a stoichiometric excess of up to about 50 percent may be desired, and more preferably a stoichiometric excess in the range of from about 10 to 20 percent.

[0074] It is anticipated that the molar volume changes induced during the reaction may have important effects on the final product. Since the reaction of interest is occurring within the pore spaces between diamond grains, a reaction which promotes an overall increase in molar volume will likely not proceed to completion because the volume between diamond grains is highly limited by the pressure applied by the HPHT or UHPHT apparatus. Conversely, a reaction which promotes a large molar volume reduction may cause microstructural problems such as micro cracking in the reacted material if the reacted volume is not large enough to fill the initial pore size. It is clear that through an engineered combination of reactants (i.e. Si and SiC) the molar volume change can be tailored over a broad range to help solve potential micro structure-related problems. Table I below presents reactant and product molar volume per mole Co data for reactions I and II presented above.

[0075] TABLE 1

[0076] Reactant Product Molar Molar

[0077] Molar Molar Volume Volume

[0078] Volume Volume Change Change

[0079] Reaction (cc) (cc) (cc) (%)

[0080] (I) Co + 2Si - CoSi931.1 21.7 -9.4 -30.2

[0081] (II) Co + 2SiC - 2C 31.7 28.6 -3.1 -9.8

[0082] In an exemplary embodiment, it is desired that the types and amounts of the getter matcrial(s) be carefully selected to enable formation of a PDC material during the consolidation and sintering process that provides a desired level of improvement in thermal stability while also not adversely affecting the sintered product, e.g., displaying minimal sintering defects such as microcracks. Ideally, the type and amount of the getter materials used to form PDC materials of this invention will be that which produces an ideal combination of optimal PDC compact physical properties and enables robust manufacturability.

[0083] While the superabrasive compact 10 is illustrated as having a certain configuration, it is to be understood that PDC compacts of this invention can be configured having a variety of different shapes and sizes depending on the particular end wear and / or cutting application.

[0084] Additionally, it is to be understood that PDC compacts of this invention comprise a PDC body that is either entirely or partially formed from the PDC material of this invention. In the exemplary embodiment illustrated in FIG. 2, the PDC compact comprises a PDC body that is made up entirely of the PDC material of this invention, i.e., comprising the reaction product of the binder / catalyst and getter material distributed throughout. Alternatively, FIG. 2 illustrates a PDC compact embodiment 10 of this invention where only a portion of the PDC body 10 is formed from the PDC material of this invention. In such embodiment, the PDC body 10 comprises a first region 24 that comprises the PDC material of this invention, and a second region 26 positioned adjacent the first region that does not. The second region 26 can be positioned adjacent to a working surface of the PDC compact to take advantage of the improved thermal stability. The first region can comprise any type of conventional PDC material or non- PCD-containing material.

[0085] In addition to the specific silicon getter materials discussed above, PDC materials of this invention can be prepared by using materials or elements other than silicon or silicon-containing compounds that are known to both react with the binder / catalyst material and form a compound having a level of thermal stability that is greater than that of the binder catalyst alone. It is desired that elements useful for this purpose meet the following requirements.

[0086] (a) They must form thermally stable compounds with the binder / catalyst over a wide range of stoichiometry;

[0087] (b) The reaction between the binder / catalyst and the getter element must preferably take place in the liquid phase so that the reactions proceed in a reasonable time, or solid state diffusion of the binder / catalyst in these elements must be rapid (and vice versa). Thus, the binary compound formed should have a eutectic melting temperature reasonably close to typical PDC processing temperatures;

[0088] (c) The element should not have strong solvent-catalyst effects on diamond at typical PDC reaction temperatures and pressures, and must also be a strong carbide former, so that any material that does not react with the binder / catalyst will combine with some of the diamond to provide a stable carbide phase in the matrix.

[0089] Table 2 presented below includes other suitable getter materials useful for preparing PDC materials of this invention according to the principles of this invention discussed above: TABEE 2

[0090] Approximate range of binary compositions that will result in the

[0091] Eutectic Melting formation of stable

[0092] Temperature(s) Stable Compounds compounds

[0093] Element (° C.) Formed with Cobalt (in at % Co)

[0094] Al 1400 AI9C02, AI3C04, 50-76

[0095] AI5C02

[0096] B 1090 BC02, BCo 18-56

[0097] Be 1120, 1200 BeCo, Be2Co5 49-80

[0098] Mo 1340 M0C03, MoeCo? 26-46

[0099] Nb 1235 NbCo, NbCo227-53

[0100] Si 1402 SiCo3, SiCo2, SiCo, 33-88

[0101] Si2Co

[0102] Ta 1276 TaCo, TaCo2 27-55

[0103] Ti 1025, 1135 TiCo2, TiCo, Ti2Co 33-92

[0104] V 1240 VC03, VCo, V3C0 7-92

[0105] Zr 986, 1230 Zr2Co, ZrCo, ZrCo2 33-85

[0106] Still in FIG. 3, in yet another embodiment, a pre-sintered tungsten carbide green body 32 may be inserted into the cup 38 instead of cemented tungsten carbide. Further in another embodiment, a solid binderless polycrystalline diamond disc 36 having a near full density may be used instead of diamond feeds or powders. In another embodiment, instead of loading two separate diamond layers, a first portion containing carbons or graphite or modified diamond particles without catalytic materials is loaded onto the cup 38 and a cemented tungsten carbide 32 is loaded on the top of the first portion. A load of lOOKg to densify the loaded materials. The loaded cup is further assembled using HPHT cell components and is subjected to the cubic press for HPHT sintering process under 16GPa and 2300 C. The sintered piece is further ground and machined to the final size of the PDC product as illustrated in the FIG. 2. The polycrystalline diamond layer 34 is formed through the direct contact of carbon to the catalyst / binder swept from the cemented carbide.

[0107] As shown in FIG. 4, a metal cup 48 (such as Ta or Nb, for example) is loaded with a first portion of a flat solid binderless polycrystalline diamond disc 46 having a near full density. Subsequently, a second portion of a flat fully leached diamond disc 44 may be loaded on top of the first portion 46. A flat cemented carbide substrate 42 is inserted into the cup 48. Its flat interface touches the fully leached diamond disc directly. The loaded cup 40 is further assembled using HPHT cell components and is subjected to a cubic press for HPHT sintering process under >5.5GPa and 1500 C. The sintered piece is further ground and machined to the final size of the PDC product as illustrated in the FIG. 2.

[0108] Alternatively, still in FIG. 4, an unleached PDC diamond table 44 instead of leached PDC diamond table is loaded into the cup 48 with its planar diamond surface directly contacting the first portion 46.

[0109] In the event that thermally stable PDC compacts of this invention include a substrate formed from cemented tungsten carbide, it may be desirable to place a barrier layer between the substrate and the PDC material to prevent unwanted infiltration of extra cobalt therein which could adversely impact the thermal stability of the resultant PDC material. Such a barrier layer can be positioned between the substrate and the PDC material, or can be positioned within the PDC material a desired distance from the substrate. Materials useful for forming such a barrier layer include refractory metals that would tend to form carbides, such as Zr, Nb, Mo, Ta, as well as noble metals such as Ru, Re, Rh and Pt.

[0110] The above-identified PDC material first embodiment will be better understood with reference to the following example: Example 1

[0111] PDC cutters are produced by the methods described in the prior art, composed of a starting diamond powder with a grain size of from about 1-10 microns in diameter with diamond powder of a grain size of from about 10 nm to about 5 microns in diameter and a metal carbide, such as tungsten carbide, attached to the polycrystalline diamond via an interface between the polycrystalline diamond and tungsten carbide.

[0112] The Ta cup is loaded by a volume of diamond feed, followed by inserting a WC substrate (OD 0.711”). The WC substrate is pre-sintered with cobalt. The assembled Ta cup was further encapsulated with salt and graphite sleeves as well as some graphite pills. The Ta cup is fit inside the sleeves tightly. The encapsulated assembly is transferred into cell loading area, and the entire body is loaded into the cell specifically designed for cubic press. The cell is then loaded into the space formed by the cubic press anvils and is applied ultra-high pressure and high temperature (UHPHT) cycle to the cell for 30 minutes. The soak pressure is maintained around 15.0 GPa and the soak temperature was about 1550° C. The soak time for bonding of the thermally stable disc to the carbide was about 10 minutes. After the bonding cycle, the cup is taken out of the pressed cell for further post processing.

[0113] The cutter is ground and finished to 16 mm in diameter, and 13.2 mm in height. A 45 degree bevel is placed on the edge of the diamond, with a thickness of about 0.4 mm.

[0114] While reference has been made to specific embodiments, it is apparent that other embodiments and variations can be devised by others skilled in the art without departing from their spirit and scope. The appended claims are intended to be construed to include all such embodiments and equivalent variations.

Claims

ClaimsWe claims:

1. A superabrasive compact, comprising: a diamond body, wherein the diamond body comprises: a first phase comprising a binderless intercrystalline diamond-to-diamond bonded matrix extending throughout the diamond body; and a second phase comprising a binder / catalyst within interstitial regions of intercrystalline bonded diamond matrix; wherein the first phase is substantially free of the binder / catalyst material; a metallic substrate in direct contact with the diamond body wherein the diamond body includes a first region comprising the catalyst / binder material and a second region is substantially free of the binder / catalyst, and wherein the second region is positioned along a wear surface of the superabrasive compact.

2. The superabrasive compact of claim 1, wherein the binder / catalyst material comprises cobalt.

3. The superabrasive compact of claim 1 or 2, wherein the second region is substantially free of porosity.

4. The superabrasive compact of any one of claims 1-3, wherein the metallic substrate comprises a metal carbide.

5. The superabrasive compact of any one of claims 1-4, wherein the metal carbide comprises tungsten carbide.

6. The superabrasive compact of any one of claims 1-5, wherein second region is substantially free of metal.

7. The superabrasive compact of any one of claims 1-6, wherein the metal comprises a catalyst.

8. The superabrasive compact of any one of claims 1-7, wherein the catalyst comprises cobalt.

9. The superabrasive compact of any one of claims 1-8, wherein an amount of catalyst / binder material within the first region of the body continuously increases with distance from the second region.

10. A superabrasive compact, comprising: a diamond body comprising: a first region; a second region, wherein the first region comprises a catalyst / binder material and a second region is substantially free of the binder, and wherein the second region is positioned along a wear surface of the superabrasive compact, wherein the second region comprises a binderless polycrystalline diamond material, wherein the second region is substantially free of porosity..

11. The superabrasive compact of claim 10, wherein the second region is substantially free of metal.

12. The superabrasive compact of any one of claims 10-11, wherein the metal comprises a catalyst.

13. The superabrasive compact of any one of claims 10-12, wherein the catalyst comprises cobalt.

14. The supcrabrasivc compact of any one of claims 10-13, wherein an amount of catalyst / bindcr material within the first region of the body continuously increases with distance from the second region.

15. The superabrasive compact of any one of claims 10-14, wherein the diamond body comprises: a first phase comprising a binderless intercrystalline diamond-to-diamond bonded matrix extending throughout the diamond body; and a second phase comprising a binder / catalyst within interstitial regions of intercrystalline bonded diamond matrix.

16. A superabrasive compact, comprising: a diamond body, wherein the diamond body comprises:a first phase comprising a binderless intercrystalline diamond-to-diamond bonded matrix extending throughout the diamond body; and a second phase comprising a binder within interstitial regions of intercrystalline bonded diamond matrix; a metallic substrate in direct contact with the diamond body, wherein the diamond body includes a first region and a second region, and wherein the second region is positioned along a wear surface of the superabrasive compact, wherein the second region is substantially free of porosity and has substantially binderless intercrystalline diamond-to-diamond bonded matrix from a wearing surface.

17. The superabrasive compact of claim 16, wherein the metallic substrate comprises carbide.

18. The superabrasive compact of any one of claims 16-17, wherein the carbide comprises tungsten carbide.

19. The superabrasive compact of any one of claims 16-18, wherein an amount of binder material within the first region of the body continuously increases with distance from the second region.

20. The superabrasive compact of any one of claims 16-19, wherein the second region comprises a plurality of diamonds with substantially free of metal.

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