Techniques for forming poly crystalline superabrasives and related methods and cutting elements for earth-boring tools

Abstract

Methods of making cutting elements for earth-boring tools can involve mixing discrete particles of superabrasive with a binder material in a solvent to form a slurry. The slurry can be vacuum dried or spray dried to deagglomerate individual precursor agglomerates from one another, the precursor agglomerates including a set of discrete particles suspended in a discrete amount of binder material. The precursor agglomerates can be sintered while exposing the precursor agglomerates to an amount of catalyst material to form agglomerates including discrete amounts of polycrystalline superabrasive while inhibiting formation of interparticle bonds between the agglomerates themselves. The agglomerates can then be sintered while exposing the agglomerates to another amount of catalyst material to form a table of the cutting element including interparticle bonds between adjacent grains of the agglomerates.

Description

[0001] Priority Statement

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 62 / 972,555, filed on February 10, 2020, entitled “Techniques for forming polycrystalline superabrasives and related methods, materials, cutting elements and drilling tools”. Technical Field

[0003] This disclosure relates overall to techniques and related methods for forming polycrystalline superabrasive agglomerates for use in drilling tools and their components, as well as other industrial applications, cutting elements, and drilling tools. More specifically, the disclosed embodiments relate to techniques for forming polycrystalline superabrasive agglomerates for use in drilling tools, the agglomerates being easier to produce, exhibiting desired size and shape characteristics, and configured to better balance performance characteristics when incorporated into larger mass polycrystalline materials, such as, for example, the table of a cutting element. Background Technology

[0004] Drilling tools used to form wellbores in underground formations may include multiple cutting elements fixed to a body. For example, a fixed-cutting-edge rotary drill bit (also known as a "scraper bit") includes multiple cutting elements fixedly attached to the drill bit body. Similarly, a roller cone rotary drill bit may include roller cones mounted on bearing pins extending from legs of the drill bit body, allowing each roller cone to rotate about its mounted bearing pin. Multiple cutting elements may be mounted to each roller cone of the drill bit.

[0005] Cutting elements used in such drilling tools typically comprise polycrystalline diamond composite (PDC) cutting elements, also known as "cutting edges," which are cutting elements comprising polycrystalline diamond (PCD) material, which can be characterized as a superabrasive or superhard material. This type of polycrystalline diamond material is formed by sintering and bonding relatively small synthetic, natural, or combinations of synthetic and natural diamond grains or crystals (referred to as "grit") together under high temperature and high pressure conditions in the presence of a catalyst such as, for example, cobalt, iron, nickel, or alloys and mixtures thereof, to form a layer of polycrystalline diamond material, also known as a diamond mesa. These processes are commonly referred to as high-temperature / high-pressure ("HTHP") processes. The cutting element substrate can comprise ceramic materials, i.e., ceramic-metal composites, such as, for example, cobalt-tungsten cemented carbide. In some cases, the polycrystalline diamond mesa can be formed on the cutting element, for example, during the HTHP sintering process. In such cases, during sintering, cobalt or other catalyst materials from the cutting element substrate can be swept into the diamond grains or crystals and used as catalyst materials for forming diamond mesa from the diamond grains or crystals. Powdered catalyst materials can also be mixed with the diamond grains or crystals before sintering the grains or crystals together in the HTHP process. However, in other methods, the diamond mesa can be formed separately from the cutting element substrate and subsequently attached to it. Summary of the Invention

[0006] In some embodiments, a method for preparing a cutting element for a drilling tool may involve mixing discrete particles of a superabrasive with a binder material in a solvent to form a slurry. The slurry may be vacuum-dried or spray-dried to depolymerize the individual precursor agglomerates, which comprise a group of discrete particles suspended in a discrete amount of binder material. The precursor agglomerates may be sintered while exposing them to a catalyst material to form an agglomerate comprising a discrete amount of polycrystalline superabrasive, while suppressing the formation of intergranular bonds between the agglomerates themselves. Optionally, the agglomerates may then be sintered while exposing them to another amount of catalyst material to form a mesa of the cutting element comprising intergranular bonds between adjacent grains of the agglomerates.

[0007] In other embodiments, the cutting element for a drilling tool may include a base and a platform supported on an end of the base. The platform may include a polycrystalline superabrasive and a filling material located in the interstitial spaces between the interbonded grains of the polycrystalline superabrasive. The polycrystalline superabrasive may include concentrated agglomerates of the interbonded grains of the superabrasive, interbonding between adjacent agglomerates, and interstitial spaces between the agglomerates, the size and shape of which are configured as if the individual grains of the superabrasive had the same size and shape as the agglomerates defining the interstitial spaces. Attached Figure Description

[0008] Although this disclosure concludes with claims that specifically point out and clearly claim protection for certain embodiments within the scope of this disclosure, various features and advantages of illustrative embodiments discussed below with reference to the accompanying drawings are also within the scope of this disclosure, wherein:

[0009] Figure 1 This is a flowchart of a method for preparing polycrystalline super abrasive agglomerates and incorporating the agglomerates into the cutting elements of a drilling tool;

[0010] Figure 2 It is a cross-sectional side view of a container used to form cutting elements for drilling tools;

[0011] Figure 3 This is a cross-sectional view of how polycrystalline superabrasives including agglomerates can appear at a magnification according to the present disclosure;

[0012] Figure 4 yes Figure 3 The shaded view highlights certain features of the polycrystalline superabrasive.

[0013] Figure 5 yes Figure 3 Another shaded view, highlighting other features of the polycrystalline superabrasive; and

[0014] Figure 6 This is a perspective side view of a drilling tool including one or more cutting elements with polycrystalline superabrasive according to the present disclosure. Detailed Implementation

[0015] The illustrations presented in the accompanying drawings are not intended to be actual views of any particular polycrystalline superabrasive, cutting element, drilling tool, or component thereof, but are merely idealized representations used to describe exemplary embodiments. Therefore, the drawings are not necessarily drawn to scale.

[0016] The disclosed embodiments typically relate to techniques for forming polycrystalline superabrasive agglomerates for use in drilling tools. These agglomerates are easier to produce, exhibit desired size and shape characteristics, and are configured to better balance performance characteristics when incorporated into larger-mass polycrystalline materials, such as, for example, the platform of a cutting element. More specifically, embodiments of methods for preparing platforms for cutting elements of drilling tools are disclosed, which may involve two sintering processes: a first sintering process for forming agglomerates comprising polycrystalline superabrasives and a second sintering process for bonding the agglomerates together to form larger-mass polycrystalline superabrasives. Larger-mass polycrystalline superabrasives can be characterized, for example, by the small average grain size of the individual grains of the polycrystalline superabrasive, the small bond lengths between adjacent bonded grains of the polycrystalline superabrasive, and the large gap regions between the bonded agglomerates of multiple bonded grains of superabrasive in a cluster. When compared with other polycrystalline super abrasives known to the inventors, the resulting polycrystalline super abrasive may have higher fracture strength, higher fracture toughness, higher wear resistance, higher resistance to crack propagation, or any combination or sub-combination of these properties.

[0017] As used herein, the terms “substantially” and “about” refer to, and include, the degree to which a given parameter, characteristic, or condition satisfies a certain degree of variance (such as within acceptable manufacturing tolerances), as would be understood by one of ordinary skill in the art. For example, a parameter that is substantially or about a specified value may be at least about 90% of the specified value, at least about 95% of the specified value, at least about 99% of the specified value, or even at least about 99.9% of the specified value.

[0018] As used herein, the term "drilling tool" means and includes any type of drill bit or tool used for drilling during the formation or enlargement of a wellbore in underground formations. For example, drilling tools include fixed-cutting-edge drill bits, roller cone drill bits, percussion drill bits, core drill bits, eccentric drill bits, bicentric drill bits, reamers, milling drills, scraper drill bits, hybrid drill bits (e.g., drill bits that include rolling elements combined with fixed cutting elements), and other drill bits and tools known in the art.

[0019] As used herein, the term "super abrasive" refers to and includes any material with a Knoop hardness of about 3,000 kgf / mm² (29,420 MPa) or greater. Super abrasives include, for example, diamond and cubic boron nitride. Super abrasives may also be referred to as "superhard" materials.

[0020] As used herein, the term "polycrystalline material" refers to and includes any structure containing multiple material grains (i.e., crystals) directly bonded together by intergranular bonds. The crystal structure of individual material grains can be randomly oriented in space within the polycrystalline material.

[0021] As used herein, the terms “intergranular bond” and “mutual bond” refer to and include any direct atomic bond (e.g., covalent bond, metallic bond, etc.) between atoms in adjacent grains of a superabrasive.

[0022] As used herein, terms for relative positioning, such as “above,” “above,” “below,” etc., refer to the orientation and positioning shown in the figures. During the formation and use of the real world, the depicted structures may take on other orientations (e.g., they may be vertically inverted, rotated about any axis, etc.). Therefore, descriptions of relative positioning must be reinterpreted according to such differences in orientation (e.g., due to reorientation, the positioning structure may be described as being “above” or to the side of other structures below it).

[0023] Figure 1 This is a flowchart of a method 100 for preparing polycrystalline superabrasive agglomerates according to the present disclosure and incorporating the agglomerates into the cutting element of a drilling tool. Method 100 may involve mixing discrete particles of superabrasive with a binder material in a solvent to form a slurry, as shown in action 102. For example, the discrete particles of superabrasive may comprise discrete grains of superabrasive in powder form (e.g., grit). More specifically, the discrete particles of superabrasive may comprise diamond grit. The average particle size of the discrete particles may be fine. For example, the average particle size of the discrete particles may be less than about 30 micrometers. More specifically, the average particle size of the discrete particles may be between about 500 nanometers and about 20 micrometers. As a specific, non-limiting example, the average particle size of the discrete particles may be between about 1 micrometer and about 10 micrometers (e.g., about 5 micrometers, about 6 micrometers, about 7 micrometers, about 8 micrometers).

[0024] Discrete particles can be mixed with a binder material, for example, by milling agglomerates with a binder material. More specifically, the discrete particles can be milled in a solvent with a certain amount of catalyst material. The catalyst material can be configured to catalyze the formation of intergranular bonds between the grains of the superabrasive particles and can include, for example, a metal-solvent catalyst (e.g., cobalt, nickel, iron, mixtures or alloys including these). The catalyst material can constitute, for example, between about 5% by weight and about 25% by weight (e.g., about 10% by weight) of the milled contents. The solvent can include, for example, isopropanol, acetone, hexane, or heptane. In some embodiments, the discrete particles, binder material, and solvent can also be milled with a wax material. The wax material can include, for example, paraffin wax or polyethylene glycol (PEG). The wax material can constitute, for example, between about 1% by weight and about 5% by weight (e.g., about 2% by weight) of the milled contents. The resulting output of the mixture can be, for example, a slurry comprising, at least partially coated with a binder material including the catalyst material and any wax material, all of which can be suspended in the solvent.

[0025] The slurry can be vacuum dried or spray-dried to depolymerize the individual precursor agglomerates, which comprise a set of discrete particles at least partially coated with discrete amounts of binder material, as shown in action 104. The resulting depolymerized precursor agglomerates may comprise, for example, discrete fine grains of a limited amount of superabrasive, surrounded and suspended within the binder material, which includes catalyst material and any wax material. The depolymerized precursor agglomerates may also have few sharp edges and irregular shapes. For example, the precursor agglomerates may have at least a substantially oval (e.g., spherical, elliptical, oblong, pear-shaped) shape.

[0026] In some embodiments, precursor agglomerates can be filtered into groups of predetermined average sizes after the precursor agglomerates have deagglomerated. Filtering can be achieved, for example, by passing the agglomerates through a mesh with openings of predetermined size. The average size of the precursor agglomerates can be, for example, about 5 mm or less. More specifically, the average diameter of the precursor agglomerates can be, for example, between about 10 micrometers and about 5 mm. As a specific, non-limiting example, the average size of the precursor agglomerates can be, for example, between about 20 micrometers and about 1 mm (e.g., about 50 micrometers, about 100 micrometers, about 250 micrometers, about 500 micrometers, about 750 micrometers). The average number of discrete superabrasive particles within a given precursor agglomerate can be, for example, between about 3 and about 20. More specifically, the average number of discrete superabrasive particles within a given precursor agglomerate can be, for example, between about 4 and about 10. As a specific, non-limiting example, the average number of discrete superabrasive particles within a given agglomerate can be between about 5 and about 7.

[0027] Precursor agglomerates comprising a binder material can be sintered while exposing the precursor agglomerates to a certain amount of catalyst material to form agglomerates comprising polycrystalline superabrasives, as shown in action 106. More specifically, sintering can produce, for example, discrete amounts of polycrystalline superabrasives in each agglomerate, comprising intergranular bonds between discrete particles of each agglomerate in each agglomerate, while suppressing the formation of intergranular bonds between the agglomerates themselves. The agglomerates can be placed, for example, in a container (e.g., Figure 2 In a container (as shown or similar), it is mixed with another amount of catalyst material in powder form. In some embodiments, a large amount of graphite may also be introduced into the container to reduce the possibility that given discrete particles may shrink and / or dissolve into the catalyst material when it is in a molten state.

[0028] In other embodiments, the agglomerates can be mixed with a pressure transmission medium before being introduced into the container and sintered. The pressure transmission medium can be used to transmit pressure to the agglomerates, maintain distance between the agglomerates to reduce the likelihood that different agglomerates can bond to each other, and is configured not to significantly change the size and shape of the agglomerates during the bonding of the grains that form the agglomerates themselves. The pressure transmission medium can have a bulk modulus, for example, between 100 GPa and 500 GPa, which can promote the formation of high-density agglomerates during sintering. The pressure transmission medium can be configured to remain solid (i.e., not melt) during sintering (e.g., during the HPHT process).

[0029] The agglomerates can, for example, be mixed with fine powder of a superabrasive and at least substantially randomly distributed among its grains. More specifically, the agglomerates can be mixed with grains of the same superabrasive as the agglomerates and at least substantially uniformly distributed therebetween, but with an average particle size of 10% or less of the average size of the agglomerates. As a specific, non-limiting example, the agglomerates can be mixed with diamond powder with an average particle size between about 10 nm and about 1 micrometer (e.g., about 0.05 micrometers, about 0.1 micrometers, about 0.5 micrometers, about 0.7 micrometers).

[0030] In some embodiments, the material used for the pressure transmission medium can be derived, for example, from materials that might otherwise be considered waste, from processes used to form individual grains located within the agglomerates. For example, the material used for the pressure transmission medium can be those superabrasive particles corresponding to a particular mesh or range of meshes: too small to be included in a batch of particles with a larger average particle size. More specifically, the material used for the pressure transmission medium can be derived from the smallest grains produced by extruding or grinding (e.g., jet grinding) superabrasives (e.g., diamond, cubic boron nitride) to produce superabrasive grit, which can typically be waste (e.g., materials sometimes referred to as "diamond powder" when diamond is a superabrasive). Thus, the pressure transmission medium according to this disclosure can advantageously use materials that would otherwise be waste. In still other embodiments, the pressure transmission medium can include powders of hard materials, such as, for example, tungsten carbide particles with a suitable average particle size.

[0031] The small size of the individual particles in the pressure transport medium can inhibit the flow of molten catalyst material from the agglomerates into the pressure transport medium. This inhibition of catalyst material flow between the particles of the pressure transport medium reduces the likelihood that adjacent agglomerates can bond to each other, the likelihood that the grains of the pressure transport medium can bond to each other and / or to a given agglomerate, and the likelihood that the size of the agglomerates can change significantly during sintering.

[0032] In some embodiments, the particles of the agglomerate and / or pressure transmission medium may be at least partially coated with a coating material to further reduce the likelihood of catalyst material from within the agglomerate flowing into the pressure transmission medium and to inhibit the diffusion of carbon material from within the agglomerate into the pressure transmission medium, and vice versa. For example, the agglomerate may be at least partially coated with a metal carbide, metal nitride, or metal carbonitride material. More specifically, the agglomerate may be coated with titanium carbide, titanium nitride, and / or titanium carbonitride (e.g., Ti(C)). X N 1-X (where X is between 0 and 1). Coating can be achieved, for example, by immersing the precursor agglomerate in a solution comprising the coating material, mixing the precursor agglomerate with a powder or slurry comprising the coating material, physical vapor deposition (PVD), chemical vapor deposition (CVD), or grinding the precursor agglomerate with powder or particles of the coating material in a manner different from applying the coating material so as not to alter the size or shape of the precursor agglomerate (e.g., by ball milling with powder or particles in solution and water as a solvent).

[0033] In some embodiments, the mixed powder, including precursor agglomerates, any powdered catalyst material, any powdered graphite material, and any pressure transmission medium, may be pre-compacted to form a green body before being introduced into the container. The mixed powder, either in powder or green form, inside the container may undergo dewaxing before hot pressing cycles. Dewaxing may be performed in a furnace under vacuum or an atmosphere consisting of hydrogen, argon, or a mixture of both. Dewaxing may be performed at a temperature between about 400°C and about 900°C and may last for a period of about 15 minutes to about 2 hours. Dewaxing can at least partially remove wax from the mixed powder or green body.

[0034] Heating the precursor agglomerates and catalyst material under pressure can bond the previously discrete grains of the individual precursor agglomerates together to form a certain mass of polycrystalline superabrasive for each given agglomerate. More specifically, the container, precursor material, and any other contents of the container (e.g., additional amounts of catalyst material, graphite material, pressure transmission medium) can be subjected to pressures of at least 5 GPa (e.g., up to 8 GPa) and exposed to at least 1,100 °C (e.g., about 1,200 °C, about 1,400 °C, about 1,450 °C) during a process sometimes referred to as “high pressure / high temperature” (HPHT) (e.g., in the HPHT process).

[0035] The growth of individual grains of the agglomerates and the mutual bonding between the previously discrete precursor agglomerates themselves can also be limited by controlling, for example, the concentration of the precursor agglomerates within the container, the time at peak temperature and pressure, or both. For example, in embodiments where the agglomerates are placed in the container along with additional catalyst material and optionally graphite material, the superabrasive of the precursor agglomerates may constitute about 50% by weight or less of the container contents. More specifically, in these embodiments, the superabrasive of the precursor agglomerates may constitute about 10% by weight to about 45% by weight (e.g., about 35% by weight, about 40% by weight) of the container contents.

[0036] As another example, relative amounts of precursor agglomerates and pressure transmission media can be selected to increase the packing density of the precursor agglomerates while reducing the likelihood that adjacent agglomerates will come into contact with each other. More specifically, the agglomerates may occupy about 72.5% by weight or less of the container contents, while the pressure transmission media constitutes the remainder (about 27.5% by weight or more). As a specific, non-limiting example, the agglomerates may occupy about 50% by weight to about 72.5% by weight (e.g., 60% by weight, 70% by weight) of the container contents, while the pressure transmission media and any accompanying materials constitute the remainder.

[0037] In some implementations, the pressure transmission medium may occupy a volume in the container equal to or greater than the percolation threshold of the pressure transmission medium within the container (i.e., the amount of pressure transmission medium that ensures continuous connectivity between particles of the pressure transmission medium and occupies additional empty space in the container, while attempting to increase the available space for agglomerates in the container). For the purposes of this document, the term "percolation threshold" means PT, as defined in Equation 1 below.

[0038] Equation 1:

[0039] Where PT is the percolation threshold, Φ is the average aspect ratio (length / width) of the pressure transmission medium, and Pʹ is defined by the following Equation 2.

[0040] Equation 2:

[0041] Where Z represents the coordination fill number calculated using the following Equation 3.

[0042] Equation 3:

[0043] Where Vf is the volume fraction of the pressure transmission medium in the container. The volume fraction Vf of the pressure transmission medium in the container can be determined by analyzing the area fraction of the pressure transmission medium in one or more two-dimensional images of the microstructure of the container's volume, and then estimating the three-dimensional volume fraction Vf based on the measured two-dimensional area fraction using standard techniques known in the field of microstructure analysis. Therefore, once the volume fraction Vf is determined from the measured two-dimensional area fraction, the Z value of Equation 3 above can be calculated using standard methods. The value of Z then allows the calculation of the Pʹ value of Equation 2 above. The same two-dimensional images of the microstructure used to measure the area fraction of the pressure transmission medium can be analyzed to measure the average aspect ratio Φ (length / width) of the pressure transmission medium. The percolation threshold PT can then be calculated according to Equation 3 above using the calculated Pʹ value and the measured average aspect ratio Φ of the pressure transmission medium.

[0044] Although the filling of the container with agglomerates and any other materials (e.g., pressure transmission media, additional catalyst materials, graphite materials) may seek to maintain separation and inhibit bonding between adjacent agglomerates while increasing the packing density, some accidental cross-bonding between adjacent previous precursor agglomerates may occur.

[0045] The average grain size of the individual grains bonded to each other within a given agglomerate can be, for example, about 10 micrometers or less. More specifically, the average grain size of the individual grains in the agglomerate can be, for example, between about 2 micrometers and about 8 micrometers. As a specific, non-limiting example, the average grain size of the individual grains forming the agglomerate can be between about 4 micrometers and about 6 micrometers. The average size of the agglomerate can be, for example, about 5 mm or less. More specifically, the average diameter of the agglomerate can be, for example, from about 10 micrometers to about 5 mm. As a specific, non-limiting example, the average size of the agglomerate can be, for example, from about 20 micrometers to about 1 mm (e.g., about 50 micrometers, about 100 micrometers, about 250 micrometers, about 500 micrometers, about 750 micrometers). The average number of grains of the superabrasive bonded to each other to form a given agglomerate can be, for example, between about 3 and about 10. More specifically, the average number of grains of the superabrasive bonded to each other to form a given agglomerate can be, for example, between about 4 and about 8. As a specific, non-limiting example, the average number of grains in a superabrasive that bond to each other to form a given agglomerate can be between about 5 and about 7.

[0046] Compared to agglomerates produced by extruding polycrystalline superabrasives into smaller particles (although still polycrystalline), the resulting agglomerates can also have fewer sharp edges and irregular shapes. For example, the agglomerates can have at least substantially oval (e.g., spherical, elliptical, oval, pear-shaped) shapes.

[0047] The agglomerates can be removed from the container and filtered into predetermined average size groups, such as, for example, any of those sizes, utilizing any of the techniques previously discussed in conjunction with the precursor agglomerates. In embodiments where the agglomerates are sintered with additional amounts of catalyst material and optionally graphite material, the agglomerates can be depolymerized by a leaching process (e.g., placement in an acid bath). In embodiments where the pressure transmission medium is placed in the container along with the precursor agglomerates, sintering can transform the particles of the pressure transmission medium into glassy aggregates bonded to each other (e.g., by weak amorphous carbon bonds). In other words, the result of sintering can be a partially sintered (e.g., “brown”) portion, comprising agglomerates of polycrystalline superabrasive confined within a matrix of single-crystal, glass-bonded grains of superabrasive. Depolymerization can involve grinding (e.g., ball milling) the brown portion and separating larger agglomerates from the reseparated grains of the pressure transmission medium by size filtration. In some embodiments, the pressure transmission medium can be reused.

[0048] In some embodiments, at least a portion of the catalyst material used in forming the agglomerates can be removed from the agglomerates. For example, the agglomerates can be exposed (e.g., immersed in) an acid (e.g., aqua regia), which can dissolve at least a portion of the catalyst material from the surfaces and interstitial spaces within the agglomerates in a process commonly referred to as "leaching." In some embodiments, the resulting agglomerates may be at least substantially free of catalyst material used to form intergranular bonds between adjacent grains of the superabrasive. For example, most of the catalyst material can be removed, and residual catalyst material can remain on one or more surfaces, and the isolation bags within the agglomerates that cannot enter the interstitial spaces can still contain catalyst material. In other embodiments, leaching can only remove excess catalyst material from the agglomerates.

[0049] In some embodiments, the agglomerates can then be sintered again while exposing them to another amount of catalyst material to form a mesa of a cutting element comprising intergranular bonds between adjacent grains of the agglomerates, as shown in action 108. For example, the agglomerates can be placed together with a substrate and another amount of catalyst material (e.g., in the form of a composite metal matrix of the substrate, a powdered catalyst material mixed with the agglomerates, or a foil of catalyst material positioned adjacent to the agglomerates) in a container (e.g., Figure 2 As shown in the diagram. Adjacent agglomerates can be bonded together to form a large-mass polycrystalline superabrasive with mesa by heating diamond gravel and catalyst material under pressure (e.g., in another HPHT process). In some embodiments, the second sintering process can be carried out using unconventional agglomerates disclosed herein as input materials according to conventional techniques known to the inventors.

[0050] In some embodiments, the resulting mesa can be at least partially leached to remove at least a portion of the catalyst material from the interstitial spaces between the interbonded grains of the agglomerated superabrasive. As known to the inventors, such leaching or partial leaching can make the mesa more resistant to temperature variations that could otherwise cause stress due to the difference in the coefficients of thermal expansion between the polycrystalline superabrasive and the catalyst and / or filler material (e.g., can make the mesa more “thermally stable”).

[0051] After the second sintering process, the concentration of the polycrystalline superabrasive on the mesa can be, for example, from about 85% to about 94% by weight. After the second sintering process, the concentration of the catalyst material on the mesa can be, for example, from about 6% to about 15% by weight.

[0052] In other embodiments, the agglomerates produced by the first sintering process may not undergo subsequent sintering processes. The agglomerates can be used as individual particles having a selectable average size, a generally smooth and rounded shape, and formed from polycrystalline superabrasives. For example, the agglomerates can be used as abrasive media in ball bearings (e.g., as a durable powder lubricant), as an additive in materials used in additive manufacturing processes (e.g., for binder spraying, polymer 3D printing), as particles in hybrid composites, as particles in wear-resistant weld overlay materials, as a particulate component in coating materials, or as a particulate additive in any concentrated heat input, high-temperature melting applications.

[0053] Figure 2 This is a cross-sectional side view of a container 202 used to form a cutting element 204 for a drilling tool. The container 202 may include, for example, two or more cup-shaped members 206 welded and / or forged together to form an inner cavity in which a base 208 for forming a platform 210 and precursor material (e.g., agglomerates, additional catalyst material) may be located. In some embodiments, the precursor material may also include unbonded particles of a superabrasive mixed with the agglomerates (e.g., diamond gravel).

[0054] After the sintering process, the cutting element 204 may include a substrate 208 and a mesa 210 supported on an end of the substrate 208. The mesa 210 may include polycrystalline superabrasive and filling material located in the interstitial spaces between the bonded grains of the polycrystalline superabrasive. Figure 2 The cutting element 204 depicted is generally shaped as a straight column, but the agglomerates and polycrystalline super abrasives according to this disclosure can be used to form cutting elements with other shapes known to the inventors, such as tooth tips, monuments and chisels.

[0055] In other embodiments, and as previously noted, the agglomerates may not be sintered a second time, but may be otherwise incorporated into components of the drilling tool or used for other applications. For example, the agglomerates may be abrasive particles within an abrasive impregnation material (e.g., agglomerates dispersed in other particles of a metal matrix bonded to a tungsten carbide composite). Such materials can be used, for example, as wear-resistant weld overlays, cutting blades, pads, the body of drilling tools, and other tools and components known to the inventors.

[0056] Figure 3 This is a cross-sectional view of how the polycrystalline super abrasive 300 including agglomerates can appear at a magnification according to the present disclosure. Figure 4 yes Figure 3 The shaded view highlights certain features of the polycrystalline super abrasive 300. Figure 5 yes Figure 3 Another shaded view, highlighting other features of the polycrystalline super abrasive 300. (By combining references) Figure 3 , Figure 4 and Figure 5 The polycrystalline super abrasive 300 can be characterized by the concentrated agglomerates 302 of the mutually bonded grains 304 of the super abrasive, the mutual bonding between adjacent agglomerates 302, and the gap space 306 between the agglomerates 302. The size and shape of the gap space are set as if each grain of the super abrasive has the same size and shape as the agglomerate 302 that defines the gap space 306.

[0057] For more specific examples Figure 4 As highlighted, agglomerates 302 can generate large clusters of concentrated polycrystalline superabrasive 300, with corresponding large interstitial spaces 306 between the agglomerates 302, where catalyst material 308 or another filling material can be positioned. For example, the distribution of individual grains 304 of the superabrasive throughout the polycrystalline superabrasive 300, as well as the distribution of the interstitial spaces 306 and the catalyst material 308 located therein, may not be uniform throughout the polycrystalline superabrasive 300. More specifically, Figure 4 The microstructures depicted can generally resemble, for example, the microstructures of polycrystalline superabrasive 300 formed by grains of superabrasive having the same average grain size as the agglomerates 302.

[0058] For more specific examples Figure 5 As highlighted in the image, the actual grain size and the bond length between adjacent grains 304 can be small.

[0059] By forming polycrystalline superabrasive 300 as disclosed herein (e.g., using a dual-sintering process), the resulting material can exhibit higher fracture strength, higher fracture toughness, and higher wear resistance than polycrystalline superabrasives formed using a single-sintering process. For example, a larger region of catalyst material 308 or other filler material occupying the interstitial spaces 306 between mutually bonded agglomerates 302 can better increase fracture strength and fracture toughness compared to other polycrystalline superabrasives with the same average grain size of the mutually bonded grains. As another example, a smaller bond length between small grains 304 and adjacent grains 304 can increase wear resistance and improve resistance to crack propagation compared to other polycrystalline superabrasives with a larger average grain size.

[0060] Figure 6 This is a perspective side view of a drilling tool 600 according to the present disclosure, including one or more cutting elements 204 having polycrystalline superabrasive. For example, the drilling tool 600 may include a body 602 and one or more cutting elements 204 that are fixedly attached to the body 602 as previously described herein (e.g., brazed in a recess extending into the body 602). Figure 6 The drilling tool 600 depicted is configured as a fixed-cutting-edge drilling bit, but the cutting element 204, which includes material according to this disclosure, can be deployed on other drill bits and tools known to the inventors.

[0061] Compared to polycrystalline superabrasives known to the inventors, polycrystalline superabrasives comprising agglomerates formed according to this disclosure can better balance performance characteristics such as, for example, fracture strength, fracture toughness, wear resistance, and resistance to crack propagation. For example, the polycrystalline superabrasives according to this disclosure can include large concentrated regions of catalyst material or other filler material, occupying the interstitial spaces between mutually bonded agglomerates, which can better increase fracture strength and fracture toughness. More specifically, compared to polycrystalline superabrasives with the same average particle size formed using conventional techniques known to the inventors, the polycrystalline superabrasives formed according to this disclosure can have larger concentrated regions of catalyst material. As another example, small bond lengths between small grains and adjacent grains can increase wear resistance and improve resistance to crack propagation. More specifically, compared to polycrystalline superabrasives with the same mean free path through interstitial spaces and / or the same density of superabrasives formed using conventional techniques known to the inventors, the polycrystalline superabrasives formed according to this disclosure can have smaller average particle size and shorter average bond lengths.

[0062] In addition, compared with other particles of super abrasives in similar size ranges known to the inventors, agglomerates formed according to this disclosure can have an optional average size spanning a range of desired average sizes, a more consistent shape and a smoother outer surface, as well as higher fracture strength, fracture toughness and resistance to crack propagation.

[0063] Additional non-limiting embodiments within the scope of this disclosure include the following aspects:

[0064] Implementation Scheme 1: A method for preparing a cutting element for a drilling tool, comprising: mixing discrete particles of a superabrasive with a binder material in a solvent to form a slurry; vacuum drying or spray drying the slurry to depolymerize the aggregates, the aggregates comprising a group of discrete particles suspended in a discrete amount of the binder material; and sintering the aggregates comprising the binder material while exposing the aggregates to a catalyst material to form a discrete amount of polycrystalline superabrasive, the polycrystalline superabrasive comprising intergranular bonds between the discrete particles of each of the aggregates, while suppressing the formation of intergranular bonds between the aggregates themselves.

[0065] Implementation Scheme 2: The method according to Implementation Scheme 1 further includes subsequently sintering the agglomerates comprising the polycrystalline super abrasive while exposing the agglomerates to another amount of catalyst material to form a mesa of the cutting element comprising intergranular bonds between adjacent grains of the agglomerates.

[0066] Implementation Scheme 3: The method according to Implementation Scheme 1 or Implementation Scheme 2, wherein forming the agglomerates comprises: placing diamond gravel and catalyst material in a container; bonding the diamond grains of the diamond gravel to each other by heating the diamond gravel and the catalyst material under pressure to bring the diamond grains of the diamond gravel into proximity to each other, thereby forming the polycrystalline superabrasive of the agglomerates; and removing the agglomerates from the container and filtering the agglomerates into predetermined average size groups to deagglomerate the agglomerates to each other.

[0067] Implementation Scheme 4: The method according to Implementation Scheme 3 further includes maintaining the concentration of the diamond grit at about 50% by weight or less when evaluating the entire contents of the container.

[0068] Implementation Scheme 5: The method according to Implementation Scheme 3 or Implementation Scheme 4 further includes selecting the average particle size of the diamond gravel to be about 30 micrometers or less.

[0069] Implementation Scheme 6: The method according to Implementation Scheme 1 or Implementation Scheme 2, wherein forming the agglomerates comprises: placing a precursor agglomerate comprising diamond gravel and catalyst material mixed with a pressure transmission medium into a container; bonding the diamond grains of the diamond gravel to each other by heating the diamond gravel and the catalyst material under pressure to bring the diamond grains of the diamond gravel into proximity to each other, thereby forming the polycrystalline superabrasive of the agglomerates; and removing the agglomerates from the container and deagglomerating the agglomerates to each other.

[0070] Implementation Scheme 7: The method according to Implementation Scheme 6, wherein depolymerizing the agglomerates comprises ball milling the agglomerates.

[0071] Implementation Scheme 8: The method according to Implementation Scheme 6 or Implementation Scheme 7, wherein placing the pressure transmission medium into the container includes placing powder of the super abrasive with an average particle size of 10% or less of the average size of the precursor agglomerates into the container.

[0072] Implementation Scheme 9: The method according to Implementation Scheme 8 further includes maintaining the concentration of the pressure transmission medium at about 27.5% by weight or more when evaluating the entire contents of the container.

[0073] Implementation Scheme 10: The method according to Implementation Scheme 8 or Implementation Scheme 9 further includes coating the precursor agglomerate with a coating material before placing the precursor agglomerate into the container.

[0074] Implementation Scheme 11: The method according to Implementation Scheme 10, wherein coating the precursor agglomerate with the coating material includes coating the precursor agglomerate with a metal carbide, metal nitride or metal carbonitride material.

[0075] Implementation Scheme 12: The method according to any one of Implementation Schemes 1 to 11 further includes controlling the exposure time to peak temperature and pressure to inhibit the growth and mutual bonding of the agglomerates.

[0076] Implementation Scheme 13: The method according to Implementation Scheme 12, wherein controlling the exposure time to peak temperature and pressure to inhibit the growth of the agglomerates includes maintaining the average size of the agglomerates at less than 100 micrometers.

[0077] Implementation Scheme 14: The method according to any one of Implementation Schemes 1 to 13, wherein mixing the discrete particles with the binder material includes grinding the discrete particles with another amount of catalyst material.

[0078] Implementation Scheme 15: The method according to any one of Implementation Schemes 1 to 14, wherein mixing the discrete particles with the solvent comprises milling the discrete particles with isopropanol, acetone, hexane or heptane.

[0079] Implementation Scheme 16: The method according to any one of Implementation Schemes 1 to 15 further includes filtering the agglomerates into predetermined average size groups before subsequently sintering the agglomerates to form the table of the cutting element.

[0080] Implementation Scheme 17: The method according to Implementation Scheme 16, wherein filtering the agglomerates into the predetermined average size group includes filtering the agglomerates into an average size of about 5 mm or less.

[0081] Implementation Scheme 18: A cutting element for a drilling tool, comprising: a base; and a platform supported on an end of the base, the platform comprising: a polycrystalline superabrasive and a filling material located in the interstitial spaces between mutually bonded grains of the polycrystalline superabrasive; wherein the polycrystalline superabrasive is characterized by concentrated agglomerates of the mutually bonded grains of the superabrasive, interbonding between adjacent agglomerates, and interstitial spaces between the agglomerates, the size and shape of the interstitial spaces being configured as if the individual grains of the superabrasive had the same size and shape as the agglomerates defining the interstitial spaces.

[0082] Implementation Scheme 19: The cutting element according to Implementation Scheme 18, wherein the distribution of the individual grains of the super abrasive is non-uniform.

[0083] Implementation Scheme 20: The cutting element according to Implementation Scheme 18 or Implementation Scheme 19, wherein the distribution of the gap space of the super abrasive is non-uniform.

[0084] Although certain exemplary embodiments have been described in conjunction with the accompanying drawings, those skilled in the art will recognize and understand that the scope of this disclosure is not limited to those embodiments expressly shown and described herein. Rather, many additions, deletions, and modifications can be made to the embodiments described herein to produce embodiments within the scope of this disclosure, such as the particularly claimed embodiments, including legal equivalents. Furthermore, features from one disclosed embodiment can be combined with features from another disclosed embodiment while still remaining within the scope of this disclosure.

Claims

1. A method for manufacturing a cutting element for a drilling tool, comprising: Discrete particles of superabrasive are mixed with binder materials in a solvent to form a slurry; The slurry is vacuum dried or spray dried to deagglomerate the individual agglomerates, the agglomerates comprising a set of discrete particles suspended in discrete amounts of the binder material; as well as The sintering process involves the agglomerates comprising the binder material, while exposing the agglomerates to a certain amount of catalyst material to form discrete amounts of polycrystalline superabrasive. Prior to sintering the agglomerates, the agglomerates are mixed with a pressure transmission medium to transmit pressure to the agglomerates and maintain the distance between the agglomerates. The polycrystalline superabrasive comprises intergranular bonds between the discrete particles of each of the agglomerates, while suppressing the formation of intergranular bonds between the agglomerates themselves.

2. The method of claim 1, further comprising subsequently sintering the agglomerate comprising the polycrystalline superabrasive while exposing the agglomerate to another amount of catalyst material to form a mesa of the cutting element comprising intergranular bonds between adjacent grains of the agglomerate.

3. The method of claim 1, wherein forming the agglomerate comprises: Precursor agglomerates, comprising diamond gravel and catalyst materials, mixed with a pressure transmission medium, are placed in a container; When the diamond grains of the diamond gravel and the catalyst material are heated under pressure to bring them close together, the diamond grains bond together to form the polycrystalline super abrasive aggregates. as well as Remove the agglomerates from the container and deagglomerate the agglomerates from each other.

4. The method of claim 3, wherein depolymerizing the agglomerates comprises ball milling the agglomerates.

5. The method of claim 3, wherein placing the pressure transmission medium into the container comprises placing powder of the superabrasive having an average particle size of 10% or less of the average size of the precursor agglomerates into the container.

6. The method of claim 5, further comprising maintaining the concentration of the pressure transmission medium at 27.5% by weight or more when evaluating the entire contents of the container.

7. The method of claim 5, further comprising coating the precursor agglomerate with a coating material before placing the precursor agglomerate into the container.

8. The method of claim 7, wherein coating the precursor agglomerate with the coating material comprises coating the precursor agglomerate with a metal carbide, metal nitride, or metal carbonitride material.

9. The method of claim 1, further comprising controlling the exposure time to peak temperature and pressure to inhibit the growth and interbonding of the agglomerates.

10. The method of claim 9, wherein controlling the exposure time to peak temperature and pressure to inhibit the growth of the agglomerates comprises maintaining the average diameter of the agglomerates at less than 100 micrometers.

11. The method of claim 1, wherein mixing the discrete particles with the binder material comprises milling the discrete particles with another amount of catalyst material.

12. The method of claim 1, wherein mixing the discrete particles with the solvent comprises milling the discrete particles with isopropanol, acetone, hexane or heptane.

13. The method of claim 2, further comprising filtering the agglomerates into predetermined average size groups before subsequently sintering the agglomerates to form the table of the cutting element.

14. The method of claim 13, wherein filtering the agglomerates into the predetermined average size group comprises filtering the agglomerates into an average diameter of 1 mm or less.

15. A cutting element for a drilling tool, comprising: Base; and A platform manufactured by the method for preparing a cutting element for a drilling tool according to any one of claims 1 to 14, the platform being supported on an end of the substrate, the platform comprising: a polycrystalline superabrasive and a filling material located in the interstitial space between the mutually bonded grains of the polycrystalline superabrasive; The polycrystalline super abrasive is characterized by concentrated agglomerates of mutually bonded grains of the super abrasive, mutual bonding between adjacent agglomerates, and gap spaces between the agglomerates, the size and shape of which are set as if each grain of the super abrasive has the same size and shape as the agglomerate defining the gap space.

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