Methods of Leaching Elements Including Superabrasive or Superhard Materials

This application is a continuation of U.S. patent application Ser. No. 16/841,339, filed 6 Apr. 2020, which application is a divisional of U.S. patent application Ser. No. 14/879,907, filed 9 Oct. 2015, which claims priority to U.S. Provisional Application Nos. 62/062,553, filed 10 Oct. 2014, and 62/096,315, filed on 23 Dec. 2014, the disclosure of each of which is hereby incorporated by reference in its entirety.

Wear-resistant, superabrasive materials are traditionally utilized for a variety of mechanical applications. For example, polycrystalline diamond (“PCD”) materials are often used in drilling tools (e.g., cutting elements, gage trimmers, etc.), machining equipment, bearing apparatuses, wire-drawing machinery, and in other mechanical systems. Conventional superabrasive materials have found utility as superabrasive cutting elements in rotary drill bits, such as roller cone drill bits and fixed-cutter drill bits. A conventional cutting element may include a superabrasive layer or table, such as a PCD table. The cutting element may be brazed, press-fit, or otherwise secured into a preformed pocket, socket, or other receptacle formed in the rotary drill bit. In another configuration, the substrate may be brazed or otherwise joined to an attachment member such as a stud or a cylindrical backing. Generally, a rotary drill bit may include one or more PCD cutting elements affixed to a bit body of the rotary drill bit.

As mentioned above, conventional superabrasive materials have found utility as bearing elements, which may include bearing elements utilized in thrust bearing and radial bearing apparatuses. A conventional bearing element typically includes a superabrasive layer or table, such as a PCD table, bonded to a substrate. One or more bearing elements may be mounted to a bearing rotor or stator by press-fitting, brazing, or through other suitable methods of attachment. Typically, bearing elements mounted to a bearing rotor have superabrasive faces configured to contact corresponding superabrasive faces of bearing elements mounted to an adjacent bearing stator.

Cutting elements having a PCD table may be formed and bonded to a substrate using an ultra-high pressure, ultra-high temperature (“HPHT”) sintering process. Often, cutting elements having a PCD table are fabricated by placing a cemented carbide substrate, such as a cobalt-cemented tungsten carbide substrate, into a container or cartridge with a volume of diamond particles positioned on a surface of the cemented carbide substrate. A number of such cartridges may be loaded into a HPHT press. The substrates and diamond particle volumes may then be processed under HPHT conditions in the presence of a catalyst material that causes the diamond particles to bond to one another to form a diamond table having a matrix of bonded diamond crystals. The catalyst material is often a metal-solvent catalyst, such as cobalt, nickel, and/or iron, that facilitates intergrowth and bonding of the diamond crystals.

In one conventional approach, a constituent of the cemented-carbide substrate, such as cobalt from a cobalt-cemented tungsten carbide substrate, liquefies and sweeps from a region adjacent to the volume of diamond particles into interstitial regions between the diamond particles during the HPHT process. The cobalt may act as a catalyst to facilitate the formation of bonded diamond crystals. A metal-solvent catalyst may also be mixed with a volume of diamond particles prior to subjecting the diamond particles and substrate to the HPHT process.

The metal-solvent catalyst may dissolve carbon from the diamond particles and portions of the diamond particles that graphitize due to the high temperatures used in the HPHT process. The solubility of the stable diamond phase in the metal-solvent catalyst may be lower than that of the metastable graphite phase under HPHT conditions. As a result of the solubility difference, the graphite tends to dissolve into the metal-solvent catalyst and the diamond tends to deposit onto existing diamond particles to form diamond-to-diamond bonds. Accordingly, diamond grains may become mutually bonded to form a matrix of polycrystalline diamond, with interstitial regions defined between the bonded diamond grains being occupied by the metal-solvent catalyst. In addition to dissolving carbon and graphite, the metal-solvent catalyst may also carry tungsten, tungsten carbide, and/or other materials from the substrate into the PCD layer of the cutting element.

The presence of the metal-solvent catalyst and/or other materials in the diamond table may reduce the thermal stability of the diamond table at elevated temperatures. For example, the difference in thermal expansion coefficient between the diamond grains and the solvent catalyst is believed to lead to chipping or cracking in the PCD table of a cutting element during drilling or cutting operations. The chipping or cracking in the PCD table may degrade the mechanical properties of the cutting element or lead to failure of the cutting element. Additionally, at high temperatures, diamond grains may undergo a chemical breakdown or back-conversion with the metal-solvent catalyst. Further, portions of diamond grains may transform to carbon monoxide, carbon dioxide, graphite, or combinations thereof, thereby degrading the mechanical properties of the PCD material.

Accordingly, it is desirable to remove metallic materials, such as metal-solvent catalysts, from a PCD material in situations where the PCD material may be exposed to high temperatures. Chemical leaching is often used to dissolve and remove various materials from the PCD layer. For example, chemical leaching may be used to remove metal-solvent catalysts, such as cobalt, from regions of a PCD layer that may experience elevated temperatures during drilling, such as regions adjacent to the working surfaces of the PCD layer.

During conventional leaching of a PCD table, exposed surface regions of the PCD table are immersed in a leaching solution until interstitial components, such as a metal-solvent catalyst, are removed to a desired depth from the exposed surface regions. The process of chemical leaching often involves the use of highly concentrated and/or corrosive solutions, such as aqua regia and mixtures including hydrofluoric acid (HF), to dissolve and remove metal-solvent catalysts from polycrystalline diamond materials. Moreover, in addition to dissolving metal-solvent catalysts from a PCD material, leaching solutions may be difficult to control, may take a long time, and may dissolve any accessible portions of a substrate to which the PCD material is attached. Therefore, improved methods for leaching PCD materials that reduce or mitigate difficulties with conventional leaching are desired.

The instant disclosure is directed to methods and assemblies for processing superabrasive elements. In some examples, the method may comprise exposing at least a portion of a polycrystalline diamond material to a processing solution, exposing an electrode to the processing solution, applying a positive charge to the polycrystalline diamond material, and applying a negative charge to the electrode. The polycrystalline diamond material may comprise a metallic material (e.g., cobalt, nickel, iron, and/or tungsten) disposed in interstitial spaces defined within the polycrystalline diamond material.

The processing solution may comprise a suitable solution that leaches the metallic material from interstitial spaces within at least a volume of the polycrystalline diamond material. According to at least one embodiment, the rate at which the processing solution leaches the metallic material from the interstitial spaces within at least the volume of the polycrystalline diamond material is increased in the presence of an electrical current between the polycrystalline diamond material and the electrode. According to various embodiments, the electrode may be disposed near at least the portion of the polycrystalline diamond material. The electrode may be disposed such that the electrode does not directly contact the polycrystalline diamond material.

The processing solution may at least partially oxidize the metallic material when the polycrystalline diamond material is processed. According to at least one embodiment, the processing solution may comprise an aqueous solution. According to some embodiments, the processing solution may comprise a buffered or a non-buffered electrolyte solution. In various embodiments, the processing solution may comprise at least one of acetic acid, ammonium chloride, arsenic acid, ascorbic acid, citric acid, formic acid, hydrobromic acid, hydrofluoric acid, hydroiodic acid, lactic acid, malic acid, nitric acid, oxalic acid, phosphoric acid, propionic acid, pyruvic acid, succinic acid, tartaric acid, and/or any suitable carboxylic acid (e.g., monocarboxylic acid, polycarboxylic acid, etc.); the processing solution may additionally or alternatively comprise at least one of an ion, a salt, and an ester of at least one of the foregoing. The electrode may comprise at least one of copper, tungsten carbide, cobalt, zinc, iron, platinum, palladium, niobium, graphite, graphene, nichrome, gold, and silver. According to various embodiments, a masking layer may be disposed over at least a portion of the polycrystalline diamond material.

In some embodiments, a cation of the metallic material may be present in the processing solution following application of the positive charge to the polycrystalline diamond material and application of the negative charge to the electrode. The cation of the metallic material may be reduced and electrodeposited on the electrode. The processing solution may comprise a first processing solution and the method may further comprise exposing at least the portion of the polycrystalline diamond material to a second processing solution (e.g., a more acidic solution than the first processing solution). At least a portion of the polycrystalline diamond material may be exposed to the second processing solution following exposure of at least the portion of the polycrystalline diamond material to the first processing solution. Additionally, at least the portion of the polycrystalline diamond material may be exposed to the second processing solution prior to exposure of at least the portion of the polycrystalline diamond material to the first processing solution. In some embodiments, an electrode for applying the positive charge abuts the polycrystalline diamond material.

According to some embodiments, a method of processing a superabrasive element may include providing a superabrasive element, exposing at least a portion of the superabrasive element to a processing solution, exposing an electrode to the processing solution, applying a first charge to the polycrystalline diamond table, and applying a second charge to the electrode. The polycrystalline diamond element may comprise a substrate and a polycrystalline diamond table bonded to the substrate, the polycrystalline diamond table comprising a metallic material disposed in interstitial spaces defined within the polycrystalline diamond table. According to various embodiments, the first charge may be applied to the polycrystalline diamond table via the substrate. In some examples, a masking layer may be disposed over at least a portion of the polycrystalline diamond table.

According to at least one embodiment, an assembly for processing a polycrystalline diamond body may include a volume of processing solution, a polycrystalline diamond body, an electrode, and a power source configured to apply a positive charge to the polycrystalline diamond body and a negative charge to the electrode. The polycrystalline diamond body and the electrode may both be in electrical communication with the processing solution. The polycrystalline diamond body may comprise a metallic material disposed in interstitial spaces defined within the polycrystalline diamond body. At least a portion of the polycrystalline diamond body and the electrode may be exposed to the volume of processing solution. The assembly may additionally include a first wire electrically connecting the power source to the polycrystalline diamond body and a second wire electrically connecting the power source to the electrode. The assembly may further include a substrate bonded to the polycrystalline diamond body, the first wire being electrically connected to the substrate by an electrode disposed on a surface portion of the substrate.

In at least one embodiment, a leached polycrystalline diamond element is disclosed. The leached polycrystalline diamond element may be fabricated according to a method. The method includes exposing an electrode and at least a portion of a polycrystalline diamond material to a processing solution. The polycrystalline diamond material includes a plurality of diamond grains defining a plurality of interstitial regions, with at least a portion of the plurality of interstitial regions including a metallic material and at least one tungsten-containing material disposed therein. The method further includes, while the electrode and the at least the portion of the polycrystalline diamond material are exposed to the processing solution, applying an electrical potential between the electrode and the polycrystalline diamond material to cause electrochemical and preferential leaching of at least a portion of the metallic material from the polycrystalline diamond material over the at least one tungsten-containing material.

In an embodiment, a polycrystalline diamond compact is disclosed. The polycrystalline diamond compact includes a substrate and a polycrystalline diamond table bonded to the substrate. The polycrystalline diamond table includes a plurality of bonded diamond grains defining a plurality of interstitial regions. The polycrystalline diamond table defines an upper surface spaced from an interfacial surface bonded to the substrate. The polycrystalline diamond table further includes an unleached volume extending inwardly from the interfacial surface, with at least a portion of the plurality of interstitial regions of the unleached volume including a metallic material and at least one tungsten-containing material disposed therein. The polycrystalline diamond table includes a leached volume extending between the unleached volume and the upper surface. The metallic material may be present in the leached volume in a first concentration and the at least one tungsten-containing material may be present in the leached volume in a second concentration of greater than 0 to about 4 weight %.

Features from any of the disclosed embodiments may be used in combination with one another in accordance with the general principles described herein. These and other embodiments, features, and advantages will be more fully understood upon reading the following detailed description in conjunction with the accompanying drawings and claims.

Throughout the drawings, identical reference characters and descriptions indicate similar, but not necessarily identical, elements. While the embodiments described herein are susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, the embodiments described herein are not intended to be limited to the particular forms disclosed. Rather, the instant disclosure covers all modifications, equivalents, and alternatives falling within the scope of the appended claims.

The instant disclosure is directed to leached superabrasive elements and leaching systems, methods, and assemblies for processing superabrasive elements. Such superabrasive elements may be used as cutting elements for use in a variety of applications, such as drilling tools, machining equipment, cutting tools, and other apparatuses, without limitation. Superabrasive elements, as disclosed herein, may also be used as bearing elements in a variety of bearing applications, such as thrust bearings, radial bearings, and other bearing apparatuses, without limitation.

The terms “superabrasive” and “superhard,” as used herein, may refer to any material having a hardness that is at least equal to a hardness of tungsten carbide. For example, a superabrasive article may represent an article of manufacture, at least a portion of which may exhibit a hardness that is equal to or greater than the hardness of tungsten carbide. Additionally, the term “solvent,” as used herein, may refer to a single solvent compound, a mixture of two or more solvent compounds, and/or a mixture of one or more solvent compounds and one or more dissolved compounds. The term “molar concentration,” as used herein, may refer to a concentration in units of mol/L at a temperature of approximately 25° C. For example, a solution comprising solute A at a molar concentration of 1 M may comprise 1 mol of solute A per liter of solution. Moreover, the term “cutting,” as used herein, may refer to machining processes, drilling processes, boring processes, and/or any other material removal process utilizing a cutting element and/or other cutting apparatus, without limitation.

illustrate a superabrasive elementaccording to at least one embodiment. As illustrated in, superabrasive elementmay comprise a superabrasive tableaffixed to or formed upon a substrate. Superabrasive tablemay be affixed to substrateat interface, which may be a planar or non-planar interface. Superabrasive elementmay comprise a rear surface, a superabrasive face, and an element side surface. In some embodiments, element side surfacemay include a substrate side surfaceformed by substrateand a superabrasive side surfaceformed by superabrasive table. Rear surfacemay be formed by substrate.

Superabrasive elementmay also comprise a chamfer(i.e., sloped or angled) formed by superabrasive table. Chamfermay comprise an angular and/or rounded edge formed at the intersection of superabrasive side surfaceand superabrasive face. Any other suitable surface shape may also be formed at the intersection of superabrasive side surfaceand superabrasive face, including, without limitation, an arcuate surface (e.g., a radius, an ovoid shape, or any other rounded shape), a sharp edge, multiple chamfers/radii, a honed edge, and/or combinations of the foregoing. At least one edge may be formed at the intersection of chamferand superabrasive faceand/or at the intersection of chamferand superabrasive side surface. For example, cutting elementmay comprise one or more cutting edges, such as an edgeand/or or an edge. Edgeand/or edgemay be formed adjacent to chamferand may be configured to be exposed to and/or in contact with a mining formation during drilling.

In some embodiments, superabrasive elementmay be utilized as a cutting element for a drill bit, in which chamferacts as a cutting edge. The phrase “cutting edge” may refer, without limitation, to a portion of a cutting element that is configured to be exposed to and/or in contact with a subterranean formation during drilling. In at least one embodiment, superabrasive elementmay be utilized as a bearing element (e.g., with superabrasive faceacting as a bearing surface) configured to contact oppositely facing bearing elements.

According to various embodiments, superabrasive elementmay also comprise a substrate chamferformed by substrate. For example, a chamfer comprising an angular and/or rounded edge may be formed by substrateat the intersection of substrate side surfaceand rear surface. Any other suitable surface shape may also be formed at the intersection of substrate side surfaceand rear surface, including, without limitation, an arcuate surface (e.g., a radius, an ovoid shape, or any other rounded shape), a sharp edge, multiple chamfers/radii, a honed edge, and/or combinations of the foregoing.

Superabrasive elementmay comprise any suitable size, shape, and/or geometry, without limitation. According to at least one embodiment, at least a portion of superabrasive elementmay have a substantially cylindrical shape. For example, superabrasive elementmay comprise a substantially cylindrical outer surface surrounding a central axisof superabrasive element, as illustrated in. Substrate side surfaceand superabrasive side surfacemay, for example, be substantially cylindrical and may have any suitable diameters relative to central axis, without limitation. According to various embodiments, substrate side surfaceand superabrasive side surfacemay have substantially the same outer diameter relative to central axis. Superabrasive elementmay also comprise any other suitable shape, including, for example, an oval, ellipsoid, triangular, pyramidal, square, cubic, rectangular, and/or composite shape, and/or a combination of the foregoing, without limitation.

According to various embodiments, superabrasive elementmay also comprise a rear chamfer. For example, a rear chamfercomprising an angular and/or rounded edge may be formed by superabrasive elementat the intersection of substrate side surfaceand rear surface. Any other suitable surface shape may also be formed at the intersection of substrate side surfaceand rear surface, including, without limitation, an arcuate surface (e.g., a radius, an ovoid shape, or any other rounded shape), a sharp edge, multiple chamfers/radii, a honed edge, and/or combinations of the foregoing.

Substratemay comprise any suitable material on which superabrasive tablemay be formed. In at least one embodiment, substratemay comprise a cemented carbide material, such as a cobalt-cemented tungsten carbide material and/or any other suitable material. In some embodiments, substratemay include a suitable metal-solvent catalyst material, such as, for example, cobalt, nickel, iron, and/or alloys thereof. Substratemay also include any suitable material including, without limitation, cemented carbides such as titanium carbide, niobium carbide, tantalum carbide, vanadium carbide, chromium carbide, and/or combinations of any of the preceding carbides cemented with iron, nickel, cobalt, and/or alloys thereof. Superabrasive tablemay be formed of any suitable superabrasive and/or superhard material or combination of materials, including, for example PCD. According to additional embodiments, superabrasive tablemay comprise cubic boron nitride, silicon carbide, polycrystalline diamond, and/or mixtures or composites including one or more of the foregoing materials, without limitation.

Superabrasive tablemay be formed using any suitable technique. According to some embodiments, superabrasive tablemay comprise a PCD table fabricated by subjecting a plurality of diamond particles to an HPHT sintering process in the presence of a metal-solvent catalyst (e.g., cobalt, nickel, iron, or alloys thereof) to facilitate intergrowth between the diamond particles and form a PCD body comprised of bonded diamond grains that exhibit diamond-to-diamond bonding therebetween. For example, the metal-solvent catalyst may be mixed with the diamond particles, infiltrated from a metal-solvent catalyst foil or powder adjacent to the diamond particles, infiltrated from a metal-solvent catalyst present in a cemented carbide substrate, or combinations of the foregoing. The bonded diamond grains (e.g., sp-bonded diamond grains), so-formed by HPHT sintering the diamond particles, define interstitial regions with the metal-solvent catalyst disposed within the interstitial regions of the as-sintered PCD body. The diamond particles may exhibit a selected diamond particle size distribution. Polycrystalline diamond elements, such as those disclosed in U.S. Pat. Nos. 7,866,418 and 8,297,382, the disclosure of each of which is incorporated herein, in its entirety, by this reference, may have magnetic properties in at least some regions as disclosed therein and leached regions in other regions as disclosed herein.

Following sintering, various materials, such as a metal-solvent catalyst, remaining in interstitial regions within the as-sintered PCD body may reduce the thermal stability of superabrasive tableat elevated temperatures. In some examples, differences in thermal expansion coefficients between diamond grains in the as-sintered PCD body and a metal-solvent catalyst in interstitial regions between the diamond grains may weaken portions of superabrasive tablethat are exposed to elevated temperatures, such as temperatures developed during drilling and/or cutting operations. The weakened portions of superabrasive tablemay be excessively worn and/or damaged during the drilling and/or cutting operations.

Removing the metal-solvent catalyst and/or other materials from the as-sintered PCD body may improve the heat resistance and/or thermal stability of superabrasive table, particularly in situations where the PCD material may be exposed to elevated temperatures. A metal-solvent catalyst and/or other materials may be removed from the as-sintered PCD body using any suitable technique, including, for example, electrochemical leaching. In at least one embodiment, a metal-solvent catalyst, such as cobalt, may be removed from regions of the as-sintered PCD body, such as regions adjacent to the working surfaces of superabrasive table. Removing a metal-solvent catalyst from the as-sintered PCD body may reduce damage to the PCD material of superabrasive tablecaused by expansion of the metal-solvent catalyst.

At least a portion of a metal-solvent catalyst, such as cobalt, as well as other materials, may be removed from at least a portion of the as-sintered PCD body using any suitable technique, without limitation. For example, electrochemical, chemical and/or gaseous leaching may be used to remove a metal-solvent catalyst from the as-sintered PCD body up to a desired depth from a surface thereof. The as-sintered PCD body may be electrochemically leached by immersion in an acid or acid solution, such as a solution including acetic acid, ammonium chloride, arsenic acid, ascorbic acid, citric acid, formic acid, hydrobromic acid, hydrofluoric acid, hydroiodic acid, lactic acid, malic acid, nitric acid, oxalic acid, phosphoric acid, propionic acid, pyruvic acid, succinic acid, tartaric acid, and/or any suitable carboxylic acid (e.g., monocarboxylic acid, polycarboxylic acid, etc.), in the presence of an electrode, such as copper, tungsten carbide, cobalt, zinc, iron, platinum, palladium, niobium, graphite, graphene, nichrome, gold, and/or silver electrode, wherein a charge is applied to the as-sintered PCD body and an opposite charge is applied to the electrode or subjected to another suitable process to remove at least a portion of the metal-solvent catalyst from the interstitial regions of the PCD body and form superabrasive tablecomprising a PCD table. For example, the as-sintered PCD body may be immersed in an acid solution in the presence of an electrode, a positive charge may be applied to the as-sintered PCD body and a negative charge may be applied to the electrode for a selected amount of time. For example, a PCD body may be positively charged and an electrode may be negatively charged for more than 4 hours, more than 10 hours, between 24 hours to 48 hours, about 2 to about 7 days (e.g., about 3, 5, or 7 days), for a few weeks (e.g., about 4 weeks), or for 1-2 months, depending on the process employed.

Even after leaching, a residual, detectable amount of the metal-solvent catalyst may be present in the at least partially leached superabrasive table. It is noted that when the metal-solvent catalyst is infiltrated into the diamond particles from a cemented tungsten carbide substrate including tungsten carbide particles cemented with a metal-solvent catalyst (e.g., cobalt, nickel, iron, or alloys thereof), the infiltrated metal-solvent catalyst may carry tungsten and/or tungsten carbide therewith and the as-sintered PCD body may include such tungsten and/or tungsten carbide therein disposed interstitially between the bonded diamond grains. The tungsten and/or tungsten carbide may be at least partially removed by the selected leaching process or may be relatively unaffected by the selected leaching process. For example, in some embodiments, the electrochemical leaching processes disclosed herein may preferentially remove metal-solvent catalyst or other metallic material (e.g., cobalt or other Group VIII metal) over other materials such as tungsten or carbide material (e.g., tungsten carbide).

In some embodiments, only selected portions of the as-sintered PCD body may be leached, leaving remaining portions of resulting superabrasive tableunleached. For example, some portions of one or more surfaces of the as-sintered PCD body may be masked or otherwise protected from exposure to a processing solution and/or gas mixture while other portions of one or more surfaces of the as-sintered PCD body may be exposed to the processing solution and/or gas mixture. Other suitable techniques may be used for removing a metal-solvent catalyst and/or other materials from the as-sintered PCD body or may be used to accelerate an electrochemical leaching process, as will be described in greater detail below. For example, exposing the as-sintered PCD body to heat, pressure, microwave radiation, and/or ultrasound may be employed to leach or to accelerate an electrochemical leaching process, without limitation. Following leaching, superabrasive tablemay comprise a volume of PCD material that is at least partially free or substantially free of a metal-solvent catalyst.

The plurality of diamond particles used to form superabrasive tablecomprising the PCD material may exhibit one or more selected sizes. The one or more selected sizes may be determined, for example, by passing the diamond particles through one or more sizing sieves or by any other method. In an embodiment, the plurality of diamond particles may include a relatively larger size and at least one relatively smaller size. As used herein, the phrases “relatively larger” and “relatively smaller” refer to particle sizes determined by any suitable method, which differ by at least a factor of two (e.g., 40 μm and 20 μm). More particularly, in various embodiments, the plurality of diamond particles may include a portion exhibiting a relatively larger size (e.g., 100 μm, 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20 μm, 15 μm, 12 μm, 10 μm, 8 μm) and another portion exhibiting at least one relatively smaller size (e.g., 30 am, 20 μm, 15 μm, 12 μm, 10 μm, 8 μm, 4 μm, 2 μm, 1 μm, 0.5 μm, less than 0.5 μm, 0.1 μm, less than 0.1 μm). In another embodiment, the plurality of diamond particles may include a portion exhibiting a relatively larger size between about 40 am and about 15 am and another portion exhibiting a relatively smaller size between about 12 am and 2 μm. In some embodiments, the plurality of diamond particles may also include three or more different sizes (e.g., one relatively larger size and two or more relatively smaller sizes), without limitation. Different sizes of diamond particle may be disposed in different locations within a polycrystalline diamond volume, without limitation. According to at least one embodiment, disposing different sizes of diamond particles in different locations may facilitate control of a leach depth, as will be described in greater detail below. It should be understood that reference to “particle sizes” herein refers to the average particle size of a plurality of particles, allowing for some slight deviation in individual particle sizes of some of the plurality of particles.

illustrate a superabrasive elementaccording to various embodiments. Superabrasive elementmay comprise a superabrasive tablethat is not attached to a substrate. As shown in, superabrasive elementmay include a rear surface, a superabrasive face, and an element side surfaceformed by superabrasive table. Superabrasive elementmay also comprise a chamfer(i.e., sloped or angled) and/or any other suitable surface shape at the intersection of element side surfaceand superabrasive face, including, without limitation, an arcuate surface (e.g., a radius, an ovoid shape, or any other rounded shape), a sharp edge, multiple chamfers/radii, a honed edge, and/or combinations of the foregoing. At least one edge, such as an edgeand/or or an edge, may be formed at the intersection of chamferand each of superabrasive faceand element side surface, respectively. Element side surfaceof superabrasive elementmay radially surround a central axisof superabrasive element.

According to various embodiments, superabrasive elementmay also comprise a rear chamfer. For example, a rear chamfercomprising an angular and/or rounded edge may be formed by superabrasive elementat the intersection of element side surfaceand rear surface. Any other suitable surface shape may also be formed at the intersection of element side surfaceand rear surface, including, without limitation, an arcuate surface (e.g., a radius, an ovoid shape, or any other rounded shape), a sharp edge, multiple chamfers/radii, a honed edge, and/or combinations of the foregoing.

Superabrasive elementmay be formed using any suitable technique, including, for example, HPHT sintering, as described above. In some examples, superabrasive elementmay be created by first forming a superabrasive elementthat includes a substrateand a superabrasive table, as detailed above in reference to. Once superabrasive elementhas been produced, superabrasive tablemay be separated from substrateto form superabrasive element. For example, prior to or following leaching, superabrasive tablemay be separated from substrateusing any suitable process, including a lapping process, a grinding process, a wire-electrical-discharge machining (“wire EDM”) process, or any other suitable material-removal process, without limitation.

According to some embodiments, superabrasive elementmay be processed and utilized either with or without an attached substrate. For example, following leaching, superabrasive elementmay be secured directly to a cutting tool, such as a drill bit, or to a bearing component, such as a rotor or stator. In various embodiments, following processing, superabrasive elementmay be attached to a substrate. For example, rear surfaceof superabrasive elementmay be brazed, welded, soldered, threadedly coupled, and/or otherwise adhered and/or fastened to a substrate, such as tungsten carbide substrate or any other suitable substrate, without limitation. Polycrystalline diamond elements having pre-sintered polycrystalline diamond bodies including an infiltrant, such as those disclosed in U.S. Pat. No. 8,323,367, the disclosure of which is incorporated herein, in its entirety, by this reference, may be leached a second time according to the processes disclosed herein after reattachment of the pre-sintered polycrystalline diamond bodies.

is a cross-sectional side view of a portion of a superabrasive table, such as the superabrasive tablesandillustrated in. Superabrasive tablemay comprise a composite material, such as a PCD material. A PCD material may include a matrix of bonded diamond grains and interstitial regions defined between the bonded diamond grains. Such interstitial regions may be at least partially filled with various materials. In some embodiments, a metal-solvent catalyst may be disposed in interstitial regions in superabrasive table. Tungsten and/or tungsten carbide may also be present in the interstitial regions.

According to various embodiments, materials may be deposited in interstitial regions during processing of superabrasive table. For example, material components of substratemay migrate into a mass of diamond particles used to form a superabrasive tableduring HPHT sintering. As the mass of diamond particles is sintered, a metal-solvent catalyst may melt and flow from substrateinto the mass of diamond particles. As the metal-solvent flows into superabrasive table, it may dissolve and/or carry additional materials, such as tungsten and/or tungsten carbide, from substrateinto the mass of diamond particles. As the metal-solvent catalyst flows into the mass of diamond particles, the metal-solvent catalyst, and any dissolved and/or undissolved materials, may at least partially fill spaces between the diamond particles. The metal-solvent catalyst may facilitate bonding of adjacent diamond particles to form a PCD layer. Following sintering, any materials, such as, for example, the metal-solvent catalyst, tungsten, and/or tungsten carbide, may remain in interstitial regions within superabrasive table.

To improve the performance and heat resistance of a surface of superabrasive table, at least a portion of a metal-solvent catalyst, such as cobalt, may be removed from at least a portion of superabrasive table. Optionally, tungsten and/or tungsten carbide may be removed from at least a portion of superabrasive table. A metal-solvent catalyst, as well as other materials, may be removed from superabrasive tableusing any suitable technique, without limitation.

For example, electrochemical leaching may be used to remove a metal-solvent catalyst from superabrasive tableup to a depth D from a surface of superabrasive table, as illustrated in. As shown in, depth D may be measured relative to an external surface of superabrasive table, such as superabrasive face, superabrasive side surface, and/or chamfer. In some examples, a metal-solvent catalyst may be removed from superabrasive tableup to a depth D of approximately 2500 μm. In additional examples, a metal-solvent catalyst may be removed from superabrasive tableup to a depth D of between approximately 100 and 1000 μm, such as about 100 am to about 250 μm, about 250 am to about 500 μm, about 500 am to about 750 μm, about 750 am to about 1000 μm, about 100 am to about 500 μm, or about 500 am to about 1000 μm.

Following leaching, superabrasive tablemay comprise a first volumeand a second volume. Following leaching, superabrasive tablemay comprise, for example, a first volumethat contains a metal-solvent catalyst. An amount of metal-solvent catalyst in first volumemay be substantially the same prior to and following leaching. In various embodiments, first volumemay be remote from one or more exposed surfaces of superabrasive table.

Second volumemay comprise a volume of superabrasive tablehaving a lower concentration of the interstitial material than first volume. For example, second volumemay be substantially free of a metal-solvent catalyst. However, small amounts of catalyst may remain within interstices that are inaccessible to the leaching process. Second volumemay extend from one or more surfaces of superabrasive table(e.g., superabrasive face, superabrasive side surface, and/or chamfer) to a depth D from the one or more surfaces. Second volumemay be located adjacent to one or more surfaces of superabrasive table. An amount of metal-solvent catalyst in first volumeand/or second volumemay vary at different depths in superabrasive table.

In at least one embodiment, superabrasive tablemay include a transition regionbetween first volumeand second volume. Transition regionmay include amounts of metal-solvent catalyst varying between an amount of metal-solvent catalyst in first volumeand an amount of metal-solvent catalyst in second volume. In various examples, transition regionmay comprise a relatively narrow region between first volumeand second volume.

are magnified cross-sectional side views of a portion of the superabrasive tableillustrated inaccording to various embodiments. As shown in, superabrasive tablemay comprise grainsand interstitial regionsbetween grainsdefined by grain surfaces. Grainsmay comprise grains formed of any suitable superabrasive material, including, for example, diamond grains. At least some of grainsmay be bonded to one or more adjacent grains, forming a polycrystalline diamond matrix.

Interstitial materialmay be disposed in at least some of interstitial regions. Interstitial materialmay comprise any suitable material, such as, for example, a metal-solvent catalyst, tungsten, and/or tungsten carbide. As shown in, interstitial materialmay not be present in at least some of interstitial regions. At least a portion of interstitial materialmay be removed from at least some of interstitial regionsduring a leaching procedure. For example, a substantial portion of interstitial materialmay be removed from second volumeduring a leaching procedure. In some embodiments, as shown in, at least some of interstitial regionsof second volumemay be partially filled with interstitial materialthat is not removed by leaching. Additionally interstitial materialmay remain in a first volumefollowing a leaching procedure.

In some examples, interstitial materialmay be removed from tableto a depth that improves the performance and/or heat resistance of a surface of superabrasive tableto a desired degree. In some embodiments, interstitial materialmay be removed from superabrasive tableto a practical limit. In order to remove interstitial materialfrom superabrasive tableto a depth beyond the practical limit, for example, significantly more time, temperature, and/or other process parameter(s) may be required. In some embodiments, interstitial materialmay be removed from superabrasive tableto a practical limit or desired degree where interstitial material remains in at least a portion of superabrasive table. In various embodiments, superabrasive tablemay be fully leached so that interstitial materialis substantially removed from a substantial portion of superabrasive table.

In at least one embodiment, as will be described in greater detail below, interstitial materialmay be leached from a superabrasive material, such as a PCD material in superabrasive table, by exposing the superabrasive material to a suitable processing solution in the presence of an electrode and applying a charge (e.g., a positive charge) to the superabrasive material and an opposite charge (e.g., a negative charge) to the electrode. Interstitial materialmay include a metal-solvent catalyst, such as cobalt, nickel, iron, and/or alloys thereof.