Patent Publication Number: US-2022220629-A1

Title: Methods of leaching a superabrasive body and related apparatuses and systems

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/374,745 titled “Methods of Leaching a Superabrasive Body and Apparatuses and Systems for the Same” and filed 3 Apr. 2019, which application is a continuation of U.S. patent application Ser. No. 15/190,471 titled “Methods of Leaching a Superabrasive Body and Apparatuses and Systems for the Same” and filed 23 Jun. 2016, which claims priority to U.S. Provisional Application No. 62/187,574 filed on 1 Jul. 2015, the disclosure of each of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     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. 
     Superabrasive elements having a superabrasive body or layer (e.g., a PCD table), may be formed and bonded to a substrate to form a compact, such as a polycrystalline diamond compact (“PDC”). Often, superabrasive elements that have a PCD table are fabricated by placing a cemented carbide substrate, such as a cobalt-cemented tungsten carbide substrate, into a container with a volume of diamond particles positioned on a surface of the cemented carbide substrate. The substrate and diamond particle volumes may then be processed under diamond-stable high-pressure high-temperature (“HPHT”) conditions in the presence of a catalyst material, which causes the diamond particles to bond to one another to form a diamond table including a plurality of bonded diamond grains having interstitial regions therebetween. The catalyst material is often a metal-solvent catalyst, such as cobalt, nickel, or iron, which facilitates intergrowth and bonding of the diamond crystals. The catalyst may sweep in from the cemented-carbide substrate, such as cobalt from a cobalt-cemented tungsten carbide substrate, which 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 presence of the metal-solvent catalyst and/or other materials in the PCD table may reduce a thermal stability of the PCD table at elevated temperatures. For example, a difference in the coefficients of thermal expansion between the diamond grains and the metal-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 to graphite catalyzed by the metal-solvent catalyst. 
     Chemical leaching may be used to dissolve and remove the metal-solvent catalyst from the PCD table. Conventional chemical leaching techniques include soaking the PCD or the entire PDC in highly concentrated and corrosive (e.g., strongly acidic or basic) leaching solutions to dissolve and remove metal-solvent catalysts from PCD. 
     However, typical soaking times for the leaching process may include days, weeks, or months. Further, the leaching solutions can dissolve any portions of the substrate exposed to the leaching solution. Accordingly, when a PCD must be leached—in order to limit potential damage to the substrate—the PCD can be formed, leached, and then bonded to a substrate, or a masking technique can be used during leaching of a PDC. 
     Manufacturers and users of superabrasive elements, such as PDCs, continue to seek improved processing techniques. 
     SUMMARY 
     Embodiments of the disclosure relate to methods of removing interstitial constituents from superabrasive bodies, and systems and apparatuses for the same. In an embodiment, a method of removing interstitial constituents from superabrasive body is disclosed. The method includes providing an ionic transfer assembly. The ionic transfer assembly includes a first electrical connection operably coupled to a superabrasive body including a plurality of bonded superabrasive grains and at least one interstitial constituent. The ionic transfer assembly includes an ionic transfer medium in contact with the superabrasive body and an ionic reservoir in ionic communication with the ionic transfer medium and separated from the superabrasive body by the ionic transfer medium. The ionic reservoir includes a second electrical connection operably coupled thereto. The method includes applying a voltage between the first and second electrical connections and removing at least some of the at least one interstitial constituent from the superabrasive body through the ionic transfer medium to the ionic reservoir. 
     In an embodiment, a method of removing interstitial constituents from a PDC is disclosed. The method includes providing an ionic transfer assembly. The ionic transfer assembly includes at least one PDC including a PCD table having a plurality of bonded diamond grains with at least one interstitial constituent disposed therebetween, an upper surface, an interfacial surface, and a lateral surface extending between the upper surface and the interfacial surface. The PDC includes a substrate having a substrate interfacial surface bonded to the interfacial surface of the PCD table. The ionic transfer assembly includes a first electrical connection operably coupled to the substrate. The ionic transfer assembly of the method includes an ionic transfer medium in contact with the PCD table and an ionic reservoir in contact with the ionic transfer medium, the ionic transfer medium positioned between the PCD table and the ionic reservoir. The ionic transfer assembly includes a second electrical connection operably coupled to the ionic reservoir. The method includes applying a voltage between the first and second electrical connections. The method includes removing at least some of the at least one interstitial constituent from the at least one PDC through the ionic transfer medium and the ionic reservoir. 
     In an embodiment, a method of removing interstitial constituents from a PDC is disclosed. The method includes electrically oxidizing one or more interstitial constituents present in a PCD table of the PDC. The method includes moving the oxidized one or more interstitial constituents through a selective ionic transfer medium in contact with the PCD table. The method includes receiving the one or more oxidized interstitial constituents in an ionic reservoir in chemical communication with the selective ionic transfer medium. 
     Features from any of the disclosed embodiments may be used in combination with one another, without limitation. In addition, other features and advantages of the present disclosure will become apparent to those of ordinary skill in the art through consideration of the following detailed description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings illustrate several embodiments of the disclosure, wherein identical reference numerals refer to identical or similar elements or features in different views or embodiments shown in the drawings. 
         FIG. 1A  is a schematic of an apparatus for removing interstitial constituents from a superabrasive body through an ionic transfer medium, according to an embodiment. 
         FIG. 1B  is a schematic flow diagram of a method of removing interstitial constituents from a superabrasive body through an ionic transfer medium, according to an embodiment. 
         FIGS. 2A-2G  are cross-sectional views of a contact surface between a PDC and an ionic transfer medium, and the resulting leached PDCs, according to various embodiments. 
         FIGS. 3-7  are schematic diagrams of ionic transfer assemblies, according to various embodiments. 
         FIG. 8  is a flow diagram of a method of removing interstitial constituents from a PDC including a superabrasive body, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments disclosed herein relate to methods of removing interstitial constituents from superabrasive bodies, and systems and apparatuses for the same. More specifically, embodiments disclosed herein relate to methods of removing interstitial constituents from a superabrasive body (e.g., a PCD body) through an ionic transfer medium by applying a voltage between a substrate of a PDC and an ionic reservoir separated by the ionic transfer medium. 
     An assembly for removing interstitial constituents from a superabrasive body may include a first electrical connection (e.g., electrode) operably coupled to a workpiece (e.g., a PDC) including a superabrasive body bonded to a substrate. The assembly may include an ionic transfer medium (e.g., membrane) contacting or interfacing at least a portion of the superabrasive body and separating the superabrasive body from an ionic reservoir operably coupled to (e.g., in ionic communication with) the ionic transfer medium. The ionic reservoir may include a second electrical connection (e.g., electrode) operably coupled thereto. Upon application of a voltage between the first and second electrical connections, at least some of the interstitial constituents may be oxidized to cationic form, which may then be extracted through the ionic transfer medium into the ionic reservoir, such as by an electrochemical gradient. The ionic transfer medium may act as an ion bridge between the superabrasive body and the ionic reservoir to facilitate movement of ions therebetween. 
     Typical superabrasive compacts may include PDCs, cubic boron nitride (“CBN”) compacts, or tungsten carbide compacts, among others. The embodiments herein may include PDCs (e.g., workpieces). However, any superabrasive material, such as any material having a hardness equal or greater than tungsten carbide, may be used in the methods and apparatuses disclosed herein. 
     PDCs including a PCD table may be 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. The diamond particles may exhibit one or more selected average particle sizes. The one or more selected average particle sizes may be determined, for example, by passing the diamond particles through one or more sizing sieves or by any other sizing method. In an embodiment, the plurality of diamond particles may include a relatively larger average particle size and at least one relatively smaller average particle 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). In various embodiments, the plurality of diamond particles may include a portion exhibiting a relatively larger average particle 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 average particle size (e.g., 30 μm, 20 μm, 10 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 an embodiment, the plurality of diamond particles may include a portion exhibiting a relatively larger average particle size between about 40 μm and about 15 μm and another portion exhibiting a relatively smaller average particle size between about 12 μm and 2 μm. Of course, the diamond particles may also include three or more different average particle sizes (e.g., one relatively larger average particle size and two or more relatively smaller average particle sizes), without limitation. The diamond particles may be placed adjacent to a catalyst, such as a metal-solvent catalyst (e.g., iron, nickel, cobalt, or alloys including one or more of the same) or a carbonate catalyst. The catalyst may be supplied from one or more sources such as the substrate (e.g., a cementing constituent), from a layer of catalyst positioned adjacent to the diamond powder, or may be mixed with the diamond powder (e.g., milled in with the diamond powder). The substrate may include a carbide such as one of tungsten carbide, niobium carbide, tantalum carbide, vanadium carbide, any refractory metal carbide, or combinations of any of the foregoing. The carbide substrate may include a cementing constituent, such as cobalt to form a cobalt-cemented tungsten-carbide substrate. Suitable cementing constituents may include iron, nickel, cobalt, or alloys including one or more of the same. 
     The substrate and diamond particle volumes may then be processed under diamond-stable HPHT conditions in the presence of the catalyst material, which causes the diamond particles to bond to one another to form a diamond table having a plurality of bonded diamond grains including interstitial regions therebetween. The HPHT process may be carried out in a high pressure cubic press. Suitable HPHT conditions may vary depending on the desired properties of the PCD table or PDC. Suitable HPHT temperatures may include 1000° C. and above, such as about 1200° C. to about 1600° C. Suitable HPHT pressures may include about 2 GPa or more, such as about 4 GPa to about 10 GPa, more than about 5 GPa, or more than about 7 GPa. Materials and methods of initially forming PDCs and resulting PDCs may be found in U.S. patent application Ser. No. 12/961,787 filed Dec. 7, 2010; and U.S. Pat. No. 7,866,418 issued on Jan. 11, 2011, the disclosure of each of which is incorporated herein, in its entirety, by this reference. 
     Under HPHT conditions, the catalyst material facilitates intergrowth and bonding of the diamond crystals. The catalyst may sweep in from the cemented-carbide substrate, such as cobalt from a cobalt-cemented tungsten carbide substrate, which 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 presence of the metal-solvent catalyst and/or other materials in the diamond table may reduce a thermal stability of the PCD table at elevated temperatures or during cutting operations. For example, a difference in the coefficients of thermal expansion between the bonded diamond grains and the metal-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 to graphite catalyzed by the metal-solvent catalyst. However, in order to render a PCD table thermally stable, conventional leaching may cause damage to substrates and/or require lengthy time periods (e.g., about a month) to complete. The methods and apparatuses herein may remove an interstitial constituent such as a metal-solvent catalyst from a superabrasive body sufficient to render the superabrasive body thermally stable in a relatively short amount of time and/or may provide better manufacturing yields. 
       FIG. 1A  is a schematic of an ionic transfer assembly  100  for removing at least some of the interstitial constituents from a superabrasive body. The ionic transfer assembly  100  may include a first electrical connection  102  operably coupled to a PDC  110 . The PDC  110  may include a superabrasive body  120  having a substrate  112  bonded thereto. For example, the PDC  110  may include a PDC having a PCD table and substrate bonded thereto. The PDC  110 , such as the superabrasive body  120 , may contact (e.g., electrically or chemically interface with) an ionic transfer medium  130 . The ionic transfer medium may be selected and configured to selectively transport ions therethrough. The ionic transfer medium  130  may contact an ionic reservoir  140 . The ionic transfer medium  130  and the ionic reservoir  140  may be in ionic communication (e.g., fluid or chemical communication) with each other, such that ionic species (e.g., metal cations and/or electrons) may pass from or through one to the other. The ionic transfer medium  130  may serve as a bridge or separation between the PDC  110  and the ionic reservoir  140 . The ionic reservoir  140  may include a fluid (e.g., a solution) having selected ions therein. The ionic reservoir  140  may be operably coupled to a second electrical connection  104 . The first and second electrical connections  102  and  104  may be operably coupled to one or more power sources  148 . 
     The superabrasive body  120  may include a plurality of bonded superabrasive grains (e.g., diamond) having interstitial regions therebetween. The superabrasive body  120  may include an upper surface  122 , an interfacial surface  124 , lateral surface  126  therebetween, and optionally, a peripherally extending chamfer ( FIGS. 2A-2G ) between the lateral surface  126  and the upper surface  122 . The interstitial regions may include one or more constituents therein. Interstitial constituents may include one or more of metal-solvent catalysts, other catalysts (e.g., carbonate catalysts) or reaction products thereof, metallic impurities, chemical impurities (e.g., salts), or substrate materials (e.g., tungsten carbide). The methods disclosed herein may be used to remove any of the foregoing. The techniques disclosed herein may also be used to reclaim materials from the substrate, such as carbide and/or cobalt from a cobalt-cemented tungsten carbide substrate. 
     During use of the ionic transfer assembly  100 , a bias (e.g., voltage) may be applied between the first and second electrical connections  102  and  104 . The first electrical connection  102  may have a positive potential and act as an anode, whereby at least some of the interstitial constituents in the superabrasive body  120  may be electrically removed (e.g., oxidized). For example, a metal-solvent catalyst, such as cobalt may be oxidized to cationic cobalt(II) or cobalt(III) as a result of the electrical current/voltage applied at the first electrical connection  102 . The electrical connection  104  may have a negative potential and act as a cathode, whereby the at least a portion of the ionic reservoir  140  operably coupled thereto may also act as a cathode. For example, the ionic reservoir  140  may include an electrolytic solution therein. The electrolytic solution may include anions and cations (e.g., free cations or anions in an acidic solution), and upon inducing a negative potential to the second electrical connection  104 , electrons may be supplied to the source of the negative potential (e.g., electrode), thereby attracting free cations in the ionic reservoir  140 , which may result in plating of the removed material (e.g., metallic cations) at the second electrical connection. While a bias (e.g., voltage or current) is applied at the first and second electrical connections  102  and  104 , at least some of the interstitial constituent in the PDC  110  may be ionized, dissolved, or oxidized; move through the ionic transfer medium  130 ; and move toward the negative potential at the second electrical connection  104 , thereby removing at least some of the interstitial constituent from the PDC  110 . In such a way, the ionic reservoir  140  may exhibit an ionic gradient in which positively charged ions are attracted to the negative potential upon being oxidized and are removed through the ionic transfer medium  130 . 
     Using the methods and apparatuses disclosed herein, interstitial constituents may be selectively removed from one or more regions of a superabrasive element (e.g., polycrystalline diamond element) to provide a desired leached region therein. For example, the interstitial constituents may be selectively removed from one or more surfaces of a superabrasive element inward to a depth therein, from one or more discrete regions, or in a gradient (e.g., a portions substantially free of interstitial constituents at a surface extending inward and increasing in concentration to a depth therein). The leached regions herein may have any one of differing shapes, depths, or gradients therein. Such leached regions including gradients and methods of making the same are disclosed in U.S. Provisional Patent Application No. 62/096,315 filed on Dec. 23, 2014, the disclosure of which is incorporated herein in its entirety by this reference. The methods disclosed herein may be used to efficiently leach a PCD element or other superabrasive element and provide consistent results (e.g., consistent leach depths, regions, and/or gradients). For example, the consistency of the depth of the leached region and/or an amount of residual material therein, from one PDC to another PDC may be controlled by the techniques disclosed herein. 
     Embodiments of the material and structure of the ionic transfer medium  130  may vary from one embodiment to the next. For example and as discussed more detail below, the ionic transfer medium  130  may include one or more of a gel (e.g., agarose gel); a membrane (e.g., an ion selective membrane; a partially porous membrane, or a size selective membrane); a paper, sponge, or filter material (e.g., nitrocellulose paper); a solid polymer electrode or solid polymer electrode material; a supercritical fluid in combination with a solid polymer electrode, or any other suitable medium capable of selectively transporting ions therethrough. The ionic transfer medium  130  may include an electrolyte solution or another solution configured to transport oxidized species therein. Embodiments of the structure of the ionic reservoir  140  and/or the solution therein may vary. For example, and as discussed in more detail below, the ionic reservoir  140  may include one or more of a housing including a fluid (e.g., electrolytic solution in liquid or supercritical fluid form), a discrete amount of electrolytic solution remote from the surface of a superabrasive body in a gel contacting the superabrasive body, in a gel or fluid disposed in a porous material, or in a solid polymer electrolyte. In some embodiments, the ionic reservoir  140  may be omitted, with the second electrical connection  104  coupled directly to the ionic transfer medium  130 . As discussed in more detail below, the ionic reservoir  140  may include acidic or basic solutions (e.g., a citric acid/citrate solution) of various concentrations and/or pH values. 
       FIG. 1B  is a schematic flow diagram of a superabrasive element at different points during the process of removing at least some of the interstitial constituent therefrom. At point A, the PDC  110  may be operably coupled to the first electrical connection  102 , such as described above. The PDC  110  may include superabrasive body  120  and substrate  112 , substantially as described above. For example, the superabrasive body may include a PCD table having a plurality of bonded diamond grains having at least one interstitial constituent material C in the interstitial regions therebetween. The interstitial constituent material C may include one or more of a metal-solvent catalyst (e.g., iron, nickel, cobalt, or alloys containing one or more of the same), other catalysts (e.g., one or more carbonate catalysts) or reaction products thereof, metallic impurities, chemical impurities, or substrate materials (e.g., tungsten carbide). At least a portion of the interstitial constituent material C may be configured to undergo electrolytic oxidation and/or electro-chemical dissolution upon application of a voltage thereto. For example, the interstitial constituent C may include cobalt, such as cobalt metal-solvent catalyst from the substrate or other source. The cobalt may be oxidized to cobalt(II) or cobalt(III) upon application of a voltage to the PDC  110  through the first electrical connection  102 . 
     The superabrasive body  120  (e.g., table) may be placed adjacent to or in contact with the ionic transfer medium  130 , such as having at least a portion of the upper surface  122  may be in direct contact therewith. The ionic transfer medium  130  may be positioned in contact (e.g., ionic communication) with the ionic reservoir  140 , such as a reservoir having an electrolytic solution or material therein. The ionic transfer medium  130  may be interposed between the PDC  110  and the ionic reservoir  140 . The ionic transfer medium  130  may be configured to selectively allow materials therethrough (e.g., size and/or ion specific transfer) and into the ionic reservoir  140 . The ionic reservoir  140  may include an ionic or electrolyte solution or gel, such as an acidic solution, a basic solution, or any other solution suitable for carrying a voltage. The electrolyte solution may include any number or types of ions therein. The ionic transfer medium  130  may include some of the electrolyte solution, or another solution (e.g., a different electrolyte solution, water, acid, etc.) therein. The ionic reservoir  140  may include the second electrical connection  104  operably coupled thereto (e.g., in electrical communication). The second electrical connection  104  may be configured to apply a bias thereto, which may result in a negative potential at the second electrical connection  104  and/or the portions of the ionic reservoir  140  adjacent to the second electrical connection  104 . The first and second electrical connections  102  and  104  may include any conducting material such as copper, tungsten carbide, cobalt, zinc, iron, steel, platinum, palladium, niobium, graphite, nickel, gold, silver, alloys including of any of the foregoing, or combinations of any of the foregoing. 
     At point B, a positive potential (e.g., voltage) may be applied to the first electrical connection  102 . The voltage may electrically oxidize one or more interstitial constituents C in the superabrasive body  120 . The interstitial constituent C may be oxidized to an anionic or more strongly positive ionic form to an interstitial constituent C+. The interstitial constituent C+ may be extracted from the superabrasive body  120  using one or more methods and apparatuses disclosed below. In an embodiment, the interstitial constituent C may include cobalt that is electrically oxidized to form the interstitial constituent C+, cobalt(II) or cobalt(III). The interstitial constituent C+ may be less strongly attached or attracted to one or more components of the superabrasive body, such that the continued bias may at least partially cause the interstitial constituent C+ to be motivated (e.g., by ionic or electrochemical gradient) away from the first electrical connection  102  and the superabrasive body  120  in electrical connection therewith. The interstitial constituent C+ may then move into and/or through the ionic transfer medium  130 . 
     As shown at point C, application of voltage at the second electrical connection  104  may result in a negative potential therein, whereby one or more portions of the ionic reservoir  140  operably coupled thereto may carry the negative potential. The negative potential may provide motivation (e.g., via electrochemical gradient) for any positive ions or other species in the ionic reservoir attracted to the negative potential to move towards the second electrical connection  104 . For example, the interstitial constituent C+ may be moved (e.g., pushed from the positive portion of the electrically induced gradient at the first electrical connection  102  and pulled toward the negative portion of the electrically induced gradient at the second electrical connection  104 ) toward the second electrical connection  104  by ionic attraction thereto. 
     While shown as separate, points B and C may be carried out substantially simultaneously. For example, points B and C may occur substantially simultaneously when an electrical bias (e.g., voltage) is applied from the power source (not shown) between the first and second electrical connections  102  and  104 . The bias may be supplied at both electrical connections (e.g., electrodes) from the same power source sufficient to cause the ionic transfer assembly  100  to remove at least a portion of the interstitial constituents C from the PDC  110  operably coupled thereto. The electrical bias may include a voltage of less than about 10 V between the first and second electrical connections  102  and  104 , such as about 0.01 V to about 5 V, about 0.5 V to about 3 V, 0.1 V to about 3 V, 0.4 V to about 2.4 V, about 0.5 V, 0.6 V, 0.7 V, 0.8 V, 0.9 V, or about 1.0 V may be applied between the first and second electrical connections  102  and  104 . In some embodiments, the voltage may be adjusted during the application of the electrical bias to accommodate changing conductivity in the ionic reservoir or ionic transfer medium due to migration of the interstitial constituent therein. The voltages above may be used in any of the embodiments disclosed herein. 
     While the electrical bias is applied, interstitial constituents C may be electrically oxidized adjacent to the first electrical connection  102  (e.g., at the superabrasive body  120 ) to provide interstitial constituent C+ and are moved toward the negative potential at or adjacent to the second electrical connection  104 . Specifically, the interstitial constituent C+ at or near the upper surface  122  move into the ionic transfer medium  130  and into the ionic reservoir  140  via gradient (e.g., ionic or electrochemical gradient). The interstitial constituent C+ may move through the ionic reservoir toward the negative potential. 
     As shown at point D, the interstitial constituent C+ may move through the ionic reservoir  140  toward the negative potential at the second electrical connection  104  whereby the interstitial constituent C+ may be reduced thereby allowing the interstitial constituent C to deposit (e.g., plate) at or adjacent to the second electrical connection  104 . Upon terminating the electrical bias, the interstitial constituent C remains plated onto one or more surfaces in the ionic reservoir  140  (such as at or adjacent to the second electrical connection  104 ), or as agglomerates of the interstitial constituent C in the ionic reservoir. As more interstitial constituent C+ is removed from the superabrasive body  120  at or near the upper surface  122 , the superabrasive body  120  may develop at least one region having a reduced amount of the interstitial constituent C therein. For example, the resulting leached PDC may include a superabrasive body  120 ′ having a first region  128  adjacent to the upper surface  122  and a second region  129  extending from the interfacial surface  124  inward. In an embodiment, substantially all of the interstitial constituent C may be removed from one or more portions of the superabrasive body  120  (e.g., the entire body or a discrete region therein). 
     The first region  128  may exhibit a reduced amount of at least one interstitial constituent therein compared to the second region  129 . In an embodiment, the interstitial constituent in an unleached or untreated PCD table may represent about at least about 5 weight % of the weight of the superabrasive body  120 , such as about 5 weight % to about 12 weight % of the weight of a selected region of the PCD table. In an embodiment, the interstitial constituent in the second region  129  may represent about 5 weight % to about 12 weight % of the weight of the second region  129  of the superabrasive body  120 . In an embodiment, the least one interstitial constituent in the first region  128  may represent less than about 6 weight % of the weight of a selected volume or region of the first region  128  of the superabrasive body  120 , such as about 0 weight % to about 6 weight %, about 0.5 weight % to about 3 weight %, about 1 weight % to about 5 weight %, about 0.25 weight % to about 2 weight %, greater than 0 weight percent to about 1.5 weight %, or about 1 weight % of the weight of a selected volume of the first region  128  of the superabrasive body  120 . 
     The first region  128  may extend a discrete (average) depth d into the superabrasive body  120  from the contact surface with the ionic transfer medium  130  to the second region  129 . Generally, the depth d may depend on any number of factors including one or more of duration of electrical bias, the voltage applied, the current applied, the type of ionic transfer medium, the thickness of the ionic transfer medium, the type of interstitial constituent, the electrolyte solution (e.g., composition and/or concentration), or any other suitable criteria. The depth d may extend about 50 μm or more into the superabrasive body from one or more surfaces thereof, such as about 50 μm to about the entire thickness of the superabrasive body, about 100 μm to about 500 μm, about 50 μm to about 400 μm, about 500 μm to about 1000 μm, about 600 μm to about 800 μm, over 1000 μm, 1000 μm to about 1500 μm, about 150 μm to about 250 μm, about 100 μm to about 300 μm, or about 200 μm into the superabrasive body from one or more surfaces thereof. In an embodiment, one or more portions of the superabrasive body  120 ′ may exhibit a gradient of interstitial constituent content therein. For example, after a bias is applied to the electrical connections  102  and  104  for a selected amount of time the superabrasive body  120 ′ may exhibit a gradient having a higher concentration of interstitial constituent adjacent to the interfacial surface  124  which gradually decreases to a lower concentration of interstitial constituent at or near the upper surface  122  (e.g., adjacent to those regions the of superabrasive body  120  in contact with the ionic transfer medium  130 ). Selected amounts of time for application of the bias may include 1 hour or more such as about 1 hour to about 2 weeks, about 4 hours to about 1 week, about 8 hours to about 3 days, about 12 hours to about 48 hours, about 48 hours to about 2 weeks, about 4 days to about 11 days, about 5 days to about 10 days, about 1 week, or about 24 hours. Such electrochemical leaching, (e.g., even for the short durations noted above), may reduce the amount of time necessary to form a thermally stable superabrasive element compared to conventional leaching and/or may selectively remove one or more interstitial constituents while leaving one or more other interstitial constituents within the superabrasive element. 
     While shown as a flat (e.g., planar) surface contacting the superabrasive body  120  along the upper surface  122 , the contact surface between the superabrasive body  120  and the ionic transfer medium  130  may have many configurations. Similarly and as explained in more detail below, the resulting leached superabrasive body  120 ′ may have one or more regions  128  and  129  having different amounts of the at least one interstitial constituent therein in any one of a number of configurations. The one or more regions  128  and  129  may include a gradient (e.g., a concentration gradient) of interstitial constituent therein, such as any of the gradients disclosed in U.S. Provisional Patent Application No. 62/096,315 the disclosure of which is incorporated herein above. Removing at least a portion of the interstitial constituent from at least a portion of the PDC  110  or superabrasive body  120  may include contacting at least a portion of one or more surfaces (e.g., upper surface  122 , lateral surface  126 , or chamfer) of the PDC  110  or superabrasive body  120  with at least a portion of the ionic transfer medium  130 . 
     In some embodiments, the superabrasive body or a portion thereof may be electrically and/chemically contacted (e.g., placed directly adjacent to or placed in electrical and/or chemical communication) with at least a portion of the ionic transfer medium, such that at least a portion of the interstitial constituent in the superabrasive body adjacent to the contact surface may be removed. In some embodiments, one or more of the superabrasive body or the ionic transfer medium may be configured to contact less than the entire outer surface (e.g., only one of or a portion of the upper surface, lateral surface, and/or chamfer) of the superabrasive body with the ionic transfer medium. Such embodiments may allow the interstitial constituent to be selectively removed from only a portion of the superabrasive body. 
       FIGS. 2A-2G  are cross-sectional views of the interface or contact surfaces between a PDC  210  and the ionic transfer medium  230  in various ionic transfer assemblies; and the resulting leached PDCs  210   a - 210   g . The ionic transfer medium  230  may be similar or identical to any ionic transfer medium disclosed herein. The PDC  210  may be similar or identical to the PDC  110 , with like parts having like numbering (e.g., superabrasive body  220  may be similar or identical to superabrasive body  120 ). For example, the PDC  210  may include a substrate  212  bonded to a superabrasive body  220  (e.g., a PCD table bonded to a cobalt-cemented tungsten carbide substrate). The superabrasive body  220  may include an upper surface  222 , an interfacial surface  224 , a lateral surface  226  therebetween, and optionally, a chamfer  227  extending between the lateral surface  226  and the upper surface  222 . The superabrasive body  220  may be in chemical (e.g., ionic) and/or electrical communication with the ionic transfer medium  230 , such that ionized chemical species may be selectively transported from the superabrasive body  220  through the ionic transfer medium  230 . While the following embodiments are described in terms of PDCs, the methods and systems described herein can be used with any superabrasive body. 
     As shown in  FIG. 2A , the ionic transfer medium  230  may include a substantially planar surface that contacts the PDC  210 . The PDC  210  may contact the ionic transfer medium  230  along at least a portion of the upper surface  222 . In an embodiment, positioning the PDC in contact with the ionic transfer medium  230  may include contacting the entire upper surface  222  of the superabrasive body  220  with the ionic transfer medium  230 . The resulting leached PDC  210   a  may include a first region  228  extending inward from the upper surface  222  of the superabrasive body  220   a  to depth d therein. The depth d of the region  228  may extend substantially parallel to the surface contacting the ionic transfer medium  230  (e.g., the upper surface  222 ). The depth d may extend substantially uniformly from the across the entire lateral length of the upper surface  222 . The first region  228  may include a reduced amount (e.g., as compared to the as-sintered PCD) of interstitial constituent therein. The leached PDC  210   a  may include a second region  229  extending inward from the interfacial surface  224 . The second region  229  may include substantially more of the interstitial constituent therein than the first region  228 , such as substantially the same amount of interstitial constituent that was present (in region  229 ) before applying the bias to the electrical connections. The first region  228  may include the chamfer  227  or at least a portion of the superabrasive body  220   a  adjacent to the chamfer  227 . 
     As shown in  FIG. 2B , the ionic transfer medium  230   b  may contact only a portion of the upper surface  222  of the superabrasive body  220 . The ionic transfer medium  230   b  may include a recess  231  configured to prevent or limit contact between a portion of the ionic transfer medium  230   b  with the superabrasive body  220 . For example, the recess  231  may be configured to allow only the peripheral areas of the upper surface  222  to contact the ionic transfer medium  230   b . For example, the recess  231  may extend laterally a distance of about 50% or more of the diameter of the upper surface  222 , such as about 60% to about 95%, about 75% to about 90%, or about 80% of the diameter of the upper surface  222 . The PDC  210  may contact the ionic transfer medium  230   b  along only a portion of the upper surface  222 . In an embodiment, positioning the PDC in contact with the ionic transfer medium  230   b  may include contacting only a portion of the upper surface  222  of the superabrasive body  220  with the ionic transfer medium  230   b . The resulting leached PDC  210   b  may include a first region  228  extending inward from the upper surface  222  about the peripheral portions (e.g., defining an annular first region  228 ) of the upper surface  222  of the superabrasive body  220   b  to the depth d therein. The depth d of the region  228  may extend substantially parallel to the surface contacting the ionic transfer medium  230  (e.g., the upper surface  222 ). The depth d may extend substantially uniformly inward from the periphery of the upper surface  222 , which may include at least a portion of the chamfer  227 . The leached PDC  210   b  may include a second region  229  extending inward from the interfacial surface  224 . In an embodiment, at least a portion of the second region  229  may extend to the upper surface  222 , such as a portion interior to the first region  228 . The first region  228  may include at least a portion of the chamber  227  and/or portions of the superabrasive body  220   b  adjacent to the chamfer  227 . 
     As shown in  FIG. 2C , the ionic transfer medium  230   c  may include a surface contacting the upper surface  222  and at least a portion of the lateral surface  226  of the superabrasive body  220 . The ionic transfer medium  230   c  may include a recess  231   c  configured to accommodate at least a portion of the superabrasive body  220  therein. For example, the recess  231   c  may be configured to allow at least a portion of both of the lateral surface  226  and the upper surface  222  to contact the ionic transfer medium  230   c . For example, the recess  231   c  may extend the entire diameter of the upper surface  222  and at least a portion of the length of the lateral surface  226 . In an embodiment, the recess  231   d  may be configured to extend inward at least about 10% of the length of the lateral surface  226 , such as about 10% to about 100%, about 20% to about 80%, about 40% to about 60%, or about 50% of the length of the lateral surface  226 . The PDC  210  may contact the ionic transfer medium  230   c  along the upper surface  222  and the lateral surface  226 . In an embodiment, positioning the PDC in contact with the ionic transfer medium  230   c  may include contacting the upper surface  222  of the superabrasive body  220  and at least a portion of the lateral surface  226  with the ionic transfer medium  230   c  (e.g., positioning the superabrasive body in the recess  231   c ). The resulting leached PDC  210   c  may include a first region  228  extending inward from the upper surface  222  and at least a portion of the lateral surface  226  of the superabrasive body  220   c  to the depth d therein. The depth d of the first region  228  may extend substantially parallel to the surfaces that contact the ionic transfer medium  230   c . The leached PDC  210   c  may include a second region  229  extending inward from the interfacial surface  224 . In an embodiment, at least a portion of the second region  229  may extend to the lateral surface  226 , such as between the first region  228  and the substrate  212 . The first region  228  may include at least a portion of the chamfer  227  and portions of the superabrasive body  220   c  adjacent to the chamfer  227 . 
     As shown in  FIG. 2D , the ionic transfer medium  230   d  may contact only a portion of the lateral surface  226  of the superabrasive body  220 . The ionic transfer medium  230   d  may include a recess  231   d  configured to accommodate at least a portion of the superabrasive body  220  therein. For example, the recess  231   d  may be configured to allow at least a portion of the lateral surface  226  to contact the ionic transfer medium  230   d . The recess  231   d  may extend the entire diameter of the upper surface  222  and more than the entire length of the lateral surface  226 . The recess  231   d  may be deeper than the lateral surface  226 , such that the entire lateral surface may contact the ionic transfer medium  230   d  while the upper surface  222  remains spaced therefrom, such as by air or an insulating material in the bottom of the recess  231   d . The PDC  210  may contact the ionic transfer medium  230   d  along only a portion of the lateral surface  226  or the entire lateral surface  226 . In an embodiment, positioning the PDC in contact with the ionic transfer medium  230   d  may include contacting only a portion of the lateral surface  226  of the superabrasive body  220  with the ionic transfer medium  230   d . The resulting leached PDC  210   d  may include a first region  228  extending inward from the lateral surface  226  of the superabrasive body  220   d  to the depth d therein. The depth d of the first region  228  may extend substantially parallel to the surface contacting the ionic transfer medium  230  (e.g., the lateral surface  226 ). The leached PDC  210   d  may include a second region  229  extending inward from the interfacial surface  224 . In an embodiment, at least a portion of the second region  229  may extend to the upper surface  222 , such as portion interior to the first region  228 . The first region  228  may exhibit a substantially annular configuration about at least a portion of the second region  229 . In an embodiment, the first region  228  may include at least a portion of the chamber  227  and/or portions of the superabrasive body  220   d  adjacent to the chamfer  227 . 
     As shown in  FIG. 2E , the ionic transfer medium  230   e  may contact the upper surface  222  and at least a portion of the chamfer  227  of the superabrasive body  220 . The ionic transfer medium  230   e  may include a recess  231   e  configured to accommodate at least a portion of the superabrasive body  220  therein. For example, the recess  231   e  may be configured to allow at least a portion of both of the upper surface  222  and the chamfer  227  to contact the ionic transfer medium  230   e . In an embodiment, the recess  231   e  may extend the entire diameter of the upper surface  222  and at least a portion of the length (e.g., both depth and lateral length) of the chamfer  227 . In an embodiment, the recess  231   e  may be configured to extend at least about 10% of the length of the chamfer  227 , such as about 10% to about 100%, about 20% to about 80%, about 40% to about 60%, or about 50% of the length of the chamfer  227 . The PDC  210  may contact the ionic transfer medium  230   e  along the upper surface  222  and the chamfer  227 . In an embodiment, positioning the PDC in contact with the ionic transfer medium  230   e  may include contacting the upper surface  222  of the superabrasive body  220  and at least a portion of the chamfer  227  with the ionic transfer medium  230   e  (e.g., positioning the superabrasive body in the recess  231   e ). The resulting leached PDC  210   e  may include a first region  228  extending inward from the upper surface  222  and at least a portion of the chamfer  227  of the superabrasive body  220   e  to the depth d therein. The depth d of the first region  228  may extend substantially parallel to the surfaces that contact the ionic transfer medium  230   e . The leached PDC  210   c  may include a second region  229  extending inwardly from the interfacial surface  224 . In an embodiment, at least a portion of the second region  229  may extend to the lateral surface  226 , such as between the first region  228  and the substrate  212 . 
     As shown in  FIG. 2F , the ionic transfer medium  230   f  may include a surface configured to contact at least a portion of one or more of the upper surface  222 , the lateral surface  226 , or the chamfer  227  of the superabrasive body  220 . The ionic transfer medium  230   f  may include a recess  231   f  configured to accommodate at least a portion of the superabrasive body  220  therein. The recess  231   f  may be configured to allow at least a portion of one or more of the upper surface  222 , the lateral surface  226 , or the chamfer  227  to contact the ionic transfer medium  230   f . For example, the recess  231   f  may extend along substantially the entirety of the upper surface  222 , at least a portion of the length of the lateral surface  226 , and at least a portion of the length of the chamfer  227 . The recess  231   f  may provide a contact surface for at least a portion of the upper surface  222 , at least a portion of the lateral surface  226 , and/or at least a portion of the chamfer  227 . For example, the ionic transfer medium  230   d  may cover or contact any of the distances or percentages of those surfaces described above for the upper, lateral and/or chamfer surfaces. The recess  231   f  may include a portion being deeper than the rest of the recess, such that lands  233  formed therein may only contact an outer or peripheral portion of the upper surface  222 . In an embodiment, PDC  210  may contact the ionic transfer medium  230   f  along one or more of the upper surface  222 , the lateral surface  226 , and the chamfer  227 . In an embodiment, positioning the PDC in contact with the ionic transfer medium  230   f  may include contacting at least a portion of the upper surface  222 , at least a portion of the lateral surface  226 , and/or at least a portion of the chamfer  227  with the ionic transfer medium  230   f  (e.g., positioning the superabrasive body at least partially into the recess  231   f ). In an embodiment, positioning the PDC in contact with the ionic transfer medium  230   f  may include contacting at least a portion of the upper surface  222  with the lands  233 . The resulting leached PDC  210   f  may include a first region  228  extending inward from peripheral portions of the upper surface  222 , at least a portion of the lateral surface  226 , and at least a portion of the chamfer  227  of the superabrasive body  220   f  to respective depths d therein. The depth(s) d of the first region  228  may extend substantially parallel to the surfaces that contact the ionic transfer medium  230   f . The leached PDC  210   f  may include a second region  229  extending inwardly from the interfacial surface  224 . In an embodiment, at least a portion of the second region  229  may extend to the lateral surface  226 , such as between the first region  228  and the substrate  212 . 
     As shown in  FIG. 2G , the ionic transfer medium  230   g  may include a substantially planar surface having one or more protrusions  237  to contact the PDC. The PDC  210  may contact the ionic transfer medium  230   g  along only a portion of the upper surface  222 . The ionic transfer medium  230   g  may include at least one protrusion  237  configured to contact less than the entire upper surface  222  of the superabrasive body  220 . For example, the at least one protrusion  237  may include a substantially planar surface set off (e.g., raised) from adjacent portions of the ionic transfer medium  230   d . The at least one protrusion may be configured to contact less than 100% of the upper surface  222 , such as about 10% to about 90%, about 25% to about 75%, about 40% to about 60%, about 50%, or about 20%. In an embodiment, the at least one protrusion  237  may be configured to contact a central portion of the upper surface  222 . In an embodiment, the at least one protrusion  237  may be configured to contact a peripheral portion of the upper surface  222 . The at least one protrusion  237  may include a plurality of protrusions configured to contact one or more discrete portions of the upper surface  222 . In an embodiment, positioning the PDC in contact with the ionic transfer medium  230   g  may include contacting a portion of the upper surface  222  of the superabrasive body  220  with the at least one protrusion  237  of the ionic transfer medium  230   g . The resulting leached PDC  210   g  may include a first region  228  extending inward from the central portion of the upper surface  222  of the superabrasive body  220   g  to depth d therein. The depth d of the first region  228  may extend substantially parallel to the surface contacting the ionic transfer medium  230   g  (e.g., the upper surface  222 ). The depth d may extend substantially uniformly across substantially the entirety of the upper surface  222 . The first region  228  may include a reduced amount (e.g., as compared to the as-sintered, non-leached PCD) of interstitial constituent therein. The leached PDC  210   g  may include a second region  229  extending inward from the interfacial surface  224 . The second region  229  may include substantially more of the interstitial constituent therein than the first region  228 , such as substantially the same amount of interstitial constituent that was present before leaching. In an embodiment, the second region  229  may extend along substantially the entire lateral surface  226 . At least a portion of the second region  229  may extend about the first region  228 . The second region  229  may include at least a portion of the chamfer  227  or at least a portion of the superabrasive body  220   g  adjacent to the chamfer  227 . 
     In an embodiment, combinations of any of the configurations disclosed with respect to  FIGS. 2A-2G  may be used by combining any of the materials or acts respectively described therewith. Any of a myriad of configurations for the ionic transfer assembly may be used to remove the interstitial constituents from a PDC (e.g., PCD of a PDC). Various embodiments are depicted in  FIGS. 3-7 . 
       FIG. 3  is a schematic diagram of an embodiment of an ionic transfer assembly  300  having a PDC  110  therein. The ionic transfer assembly  300  may include a first electrical connection  102  and a second electrical connection  104 . The first electrical connection  102  may be operably coupled (e.g., in electrical communication) to the PDC  110 . The PDC  110  may include a substrate  112  bonded to a superabrasive body  120 . In an embodiment, the PDC  110  may include only the superabrasive body  120 . In an embodiment, the first electrical connection  102  may be electrically connected to the substrate  112 . At least a portion of the PDC  110 , such as at least a portion of the superabrasive body  120 , may be in contact with an ionic transfer medium  330  such that the superabrasive body  120  is in chemical and/or electrical communication therewith. In an embodiment, the ionic transfer medium  330  may include a gel  333 . In an embodiment, removing interstitial constituents from a superabrasive body  120  may include using the gel  333  as the ionic transfer medium  330 . The gel  333  may include one or more of an agarose gel, polyethylene glycol (“PEG”) gel, ion exchange resin, or any other gel capable of selectively allowing ions (e.g., oxidized interstitial constituent) therethrough. The first electrical connection  102  or the second electrical connection  104  may include an electrically conducting material (e.g., a metal or metal alloy) configured to deliver an electrical charge, such as a plate, strip, bar, clip, wire, or coil. In an embodiment, the gel  333  may be operably coupled directly to the second electrical connection  104 . In an embodiment, a portion of the gel  333  may at least partially act as an ionic reservoir. For example, the gel  333  may include an ion source (e.g., cation exchange resin and/or electrolyte solution) therein. In such an embodiment, the gel  333  may include a portion that bridges or separates the superabrasive body from the portion of the gel  333  that acts as the ionic reservoir, such as a gradient (e.g., electrochemical, ionic, or porous gradient). As an electrical bias is applied at the first and second electrical connections  102  and  104 , the interstitial constituent present in the superabrasive body  120  may oxidize to an ionic form. Further, such an oxidized constituent may migrate through the superabrasive body and the gel  333  toward the source of negative potential (e.g., second electrical connection  104  in the portion of the gel  333  distal to the superabrasive body  120 ). In an embodiment, the gel  333  may be operably coupled (e.g., in chemical and/or electrical communication) to an ionic reservoir having the second electrical connection operably coupled thereto. 
       FIG. 4  is a schematic diagram of an embodiment of an ionic transfer assembly  400  having a PDC  110  therein. The ionic transfer assembly  400  may include a first electrical connection  102  and a second electrical connection  104 . The first electrical connection  102  may be operably coupled (e.g., in electrical communication) to the PDC  110 . The PDC  110  may include a substrate  112  bonded to a superabrasive body  120 . In an embodiment, the PDC  110  may include only the superabrasive body  120 . In an embodiment, the first electrical connection  102  may be electrically connected to the substrate  112 . At least a portion of the PDC  110 , such as at least a portion of the superabrasive body  120 , may be in contact with an ionic transfer medium  430  such that the superabrasive body  120  is in chemical and/or electrical communication therewith. The ionic transfer medium  430  may include a membrane  434 . The membrane  434  may include one or more of an ion selective membrane, a partially porous membrane, or a size selective membrane. For example, the membrane  434  may exhibit an average pore size sufficient to allow only interstitial constituents below the average pore size therethrough. In some embodiments, the membrane  434  may include one or more of polyacrylamide, one or more PEGs, polyacrylic acid, hydroxyapatite, or other suitable materials. In an embodiment, the membrane  434  may be configured as an ion selective membrane (e.g., cation selective membrane). In an embodiment, substantially only ionic materials (e.g., cationic or anionic) may be transferred therethrough. In some embodiments, suitable cation selective membranes may include polyvinyl chloride (“PVC”) based membranes, graphitic membranes, membranes having chelating resins (e.g., DOWEX™ M4195), any of the foregoing suspended in a matrix, any other material capable of facilitating transport of one or more ionic interstitial constituents from the superabrasive body, or combinations of any of the above. In an embodiment, the membrane  434  may include an ion exchange resin (e.g., cation exchange resin) configured to transport or bind at least one oxidized interstitial constituent therein. 
     In an embodiment, the membrane  434  may be operably coupled (e.g., in chemical/ionic and/or electrical communication) to an ionic reservoir  140  having the second electrical connection  104  operably coupled thereto. Optionally, the membrane  434  may serve to separate (e.g., bridge) the ionic reservoir  140  from the superabrasive body  120 . The ionic reservoir  140  may be configured as a tank, vessel, or other storage medium capable of holding a fluid therein. The second electrical connection  104  may be located (e.g., secured to) in a portion (e.g., side) of the ionic reservoir  140  (e.g., distant from the membrane  434 ). The second electrical connection  104  may include a portion of conducting material disposed at least partially within the ionic reservoir  140 . For example, the second electrical connection  104  may include a conductive plate or coil disposed in and configured to provide a relatively large area of negative potential to the ionic reservoir  140 . The ionic reservoir  140  may include a container constructed of a material configured to remain generally chemically and electrically inert during use of the ionic transfer assembly  400 . Suitable materials may include plastic, acrylic, PVC, polyetheretherketone (“PEEK”), insulated stainless steel, insulated aluminum, or any other material capable of remaining generally stable under acidic conditions, basic conditions, and/or when an electrical voltage and/or current is applied thereto. 
     The ionic reservoir  140  may include an electrolyte solution  142  therein. The electrolyte solution  142  may include any solution configured to provide one or more ions or an ionic gradient therein. In an embodiment, the electrolyte solution  142  may include an ion source having one or more of an inorganic acid (e.g., aqua regia, hydrobromic acid, hydrochloric acid, hydrofluoric acid, hydroiodic acid, nitric acid, mixtures thereof, etc.); an organic acid (e.g., ascorbic acid, benzoic acid, butyric acid, carbonic acid, citric acid, formic acid, lactic acid, malic acid, oxalic acid, propionic acid, pyruvic acid, succinic acid, etc.); or ions, salts, or esters of any of the foregoing. For example, the electrolyte solution  142  may include a citric acid/citrate solution. The electrolyte solution  142  may include any of those electrolytes, in any concentration and/or pH, disclosed in U.S. Provisional Patent Application No. 62/096,315 the disclosure of which is incorporated herein above. The electrolyte solution  142  in the ionic reservoir  140  may be heated or cooled depending on the composition thereof or the desired processing time for the PDC  110 . The temperature of the electrolyte solution  142  may be greater than about 0° C., such as about 20° C. to about 100° C. 
     The ion source may be present in the electrolyte solution in a molarity of 0.01 M or greater, such as about 0.01 M to about 10 M, about 0.1 M to about 5, about 1M to about 3 M, about 0.15 M to about 1 M, about 0.2 M, about 0.3M, about 0.5M, about 1 M, or about 2 M. The pH of the electrolyte solution  142  may be acidic such as 6.9 pH or lower. In an embodiment, the pH of the electrolyte solution  142  may be only slightly acidic, such as between 6.9 pH and about 5 pH or about 6.5 pH and about 6 pH. In an embodiment, the electrolyte solution may be strongly acidic, such as an aqua regia solution having a pH of about 2 or less. In an embodiment, the pH of the electrolyte solution  142  may be basic such as 7.1 pH or higher. In an embodiment, the electrolyte solution may include an at least 0.2 M (e.g., about 0.3 M) citric acid/citrate solution. The citric acid may serve to provide a slightly acidic electrochemical gradient suitable for transporting oxidized interstitial constituent toward the negative potential and/or to chelate the oxidized interstitial constituent (e.g., iron, cobalt, or nickel). 
     In some embodiments, as an electrical bias is applied at the first and second electrical connections  102  and  104 , the interstitial constituent present in the superabrasive body  120  may electrically oxidize to an ionic form and migrate through the superabrasive body  120  and the membrane  434  toward the source of negative potential (e.g., ionic reservoir  140  or the second electrical connection  104  associated therewith). 
       FIG. 5  is a schematic diagram of an embodiment of an ionic transfer assembly  500 . The ionic transfer assembly  500  may include a first electrical connection  102  and a second electrical connection  104 . The first electrical connection  102  may be coupled to the PDC  110 . The PDC  110  may include the substrate  112  and the superabrasive body  120 . The ionic transfer assembly  500  may include an ionic transfer medium  530  positioned and configured to contact a portion of the PDC  110 . For example, the ionic transfer medium  530  may include a filter paper  535 , spongy materials, or porous sponge-like matrix material. Suitable filter paper  535  material may include pulp (e.g., natural cellulose), glass fibers, mineral fibers, plant fibers, polymers, nitrocellulose, or combinations of any of the foregoing. 
     The filter paper  535  may be in contact with one or more of a chemical, fluid, and/or electrical connection with the ionic reservoir  140 . The filter paper  535  may be configured with a porosity sufficient to wick, transfer, and/or retain an electrolyte solution  142  from or to the ionic reservoir  140 . The filter paper  535  may be configured such that only a portion thereof is in contact with the electrolyte solution  142 . For example, the filter paper  535  may include an interfacing section  535   a  and one or more wicking sections  535   b . The interfacing section  535   a  may be positioned and configured to contact at least a portion of one or more PDCs  110  (e.g., the superabrasive body  120 ), but not contact the ionic reservoir  140  directly. The wicking sections  535   b  may extend from the interfacing section  535   a  at a non-parallel angle thereto. For example, the wicking sections  535   b  may extend from the interfacing section  535   a  and into the ionic reservoir  140 . The wicking sections  535   b  may serve to chemically connect the interfacing section  535   a  with the electrolyte solution  142 . In an embodiment, the ionic reservoir  140  may be positioned below superabrasive body  120  such with at least a portion of the filter paper  535 . The electrolyte solution  142  in the ionic reservoir  140  may include any electrolyte solution disclosed herein. 
     The second electrical connection  104  may be positioned adjacent to the filter paper  535  (e.g., in contact with the interfacing section  535   a ). The second electrical connection  104  may be configured as a plate or other surface capable of supporting the filter paper  535  and one or more PDCs  110  thereon. In an embodiment, the second electrical connection  104  may be disposed in the electrolyte solution  142  rather than adjacent (e.g., directly connected) to the filter paper  535 . Upon application of an electrical bias or voltage to the first and second electrical connections  102  and  104 , the interstitial constituent from the superabrasive body  120  may travel through the interfacing section  535   a  toward the source of negative potential at the second electrical connection  104 . The build-up of oxidized interstitial constituent in the interfacing section  535   a  may cause the filter paper to transport the oxidized interstitial constituent to the ionic reservoir  140  via electrochemical gradient. The oxidized interstitial constituent may travel to the ionic reservoir  140  via the one or more wicking sections  535   b , whereupon the interfacing section  535   a  may draw more oxidized interstitial constituent from the superabrasive body  120 . In an embodiment, the ionic transfer assembly  500  may operate without applying an electrical bias or voltage. In a working example, the ionic transfer assembly  500  was able to remove cobalt catalyst from a PCD table to depth of about 100 μm in about 7 days without applying an electrical bias thereto. In an embodiment, the ionic transfer assembly  500  may have a vertical arrangement wherein the ionic reservoir  140  is positioned below the interfacing section  535   a  of the filter paper  535 . The second electrical connection  104  may be positioned below the interfacing section  535   a  of the filter paper  535  and in electrical communication therewith. One or more PDCs  110  may be disposed on the filter paper  535  with the superabrasive body  120  facing downward, such that at least a portion of the upper surface of the superabrasive body  120  may contact (e.g., physically, electrically, or chemically interface with) the filter paper  535 . The first electrical connection  102  may be coupled to the substrate  112  such that a voltage (e.g., a positive potential) may be applied thereto. 
     In another embodiment, rather than the filter paper  535  being disposed in the electrolyte solution, a solid hydrated support (e.g., block of any ionic transfer material disclosed herein) may be disposed in the electrolyte solution  142  and have the second electrode operably connected thereto. The PDC  110  may be in contact with the solid hydrated support (e.g., positioned and configured above the surface of the electrolyte solution  142 ) to allow removal of the interstitial constituent through the solid hydrated support. The solid hydrated support may be configured to contact and/or support one or more portions of the PDC  110  (e.g., hold the PDC  110  above the surface of the electrolyte solution  142 ). 
       FIG. 6  is a schematic diagram of an embodiment of an ionic transfer assembly  600 . The ionic transfer assembly  600  may include one or more first electrical connections  102  and one or more second electrical connections  104 . The one or more first electrical connections  102  may each be coupled to at least one PDC  110 . Each PDC  110  may include the substrate  112  and the superabrasive body  120 . The ionic transfer assembly  600  may include an ionic transfer medium  630  positioned and configured to contact a portion of one or more PDCs  110 . For example, the ionic transfer medium  630  may include a solid polymer electrolyte (“SPE”)  636  having a porous construction. In an embodiment, the solid polymer electrode (“SPE”)  636  may include a dry polymer electrolyte (e.g., including a ceramic material and a polymer such as one or more of polytetrafluoroethylene (“PTFA”), a PEG, a polyethylene oxide (“PEO”), a poly(methyl methacrylate) (“PMMA”), a polyacrylonitrile (“PAN”), siloxanes, etc.), an organic ionic plastic, a gel electrolyte, or combinations of any of the foregoing. In an embodiment, the SPE  636  may also be in ionic communication with or act as the ionic reservoir. The SPE  636  may be in electrical communication with at least one second electrical connection  104 . In an embodiment, the SPE  636  may be in electrical and/or chemical communication with the second electrical connection  104 . The SPE  636  may optionally act as both the ionic transfer medium  630  and the ionic reservoir. For example, a plurality of first and second electrical connections  102  and  104  may be electrically biased such that at least a portion of the interstitial constituent of one or more superabrasive bodies  120  in contact therewith is oxidized and transferred into the SPE  636  via electrochemical gradient therein. The SPE  636  may be configured with selected porosity or chemical composition to transfer at least enough interstitial constituent therethrough or therein to leach the superabrasive body  120  to a desired depth. In an embodiment (not shown), the SPE  636  may be in contact (e.g., ionic communication) with an ionic reservoir (not shown). For example, the SPE  636  may be disposed between an ionic reservoir (not shown) and the PDC  110 . In an embodiment, the SPE  636  may be positioned substantially horizontally and one or more PDCs  110  may be positioned thereon with the superabrasive body  120  facing the SPE  636  (e.g., facing downward on top of the SPE  636 ). In an embodiment, the SPE  636  may be arranged substantially vertically with one or more PDCs  110  in ionic communication with a side surface thereof. During operation, a positive potential may be applied at the first electrical connection  102  and a negative potential may be applied at the second electrical connection  104 , which may oxidize the interstitial constituent in the superabrasive body  120  and facilitate or induce the (oxidized) interstitial constituent to move toward the negative potential at the second electrical connection  104 , thereby removing the interstitial constituent from at least a portion of the superabrasive body  120 . 
       FIG. 7  is a schematic diagram of an embodiment of an ionic transfer assembly  700 . The ionic transfer medium  730  of the ionic transfer assembly  700  may include a SPE and a supercritical fluid disposed against the PDC. The ionic transfer assembly  700  may include one or more first electrical connections  102  and one or more second electrical connections  104 . The one or more first electrical connections  102  may each be coupled to at least one PDC  110 . Each PDC  110  may include the substrate  112  and the superabrasive body  120 . Optionally, the ionic transfer assembly  700  may include a housing  150  configured to hold the PDC  110  under a fluid tight seal therein. For example, the housing  150  may include a metallic tube, pipe, or conduit configured to at least partially provide a seal around the lateral surface of the PDC, such that fluid (e.g., a gas or a liquid) or supercritical fluid may not escape between the housing  150  and the PDC  110 . In an embodiment, the housing  150  may include a sealing member (not shown) such an O-ring, flange, gasket, etc. configured to provide a seal around at least a portion of the PDC  110  in the housing  150 . The ionic transfer assembly  700  may include an ionic transfer medium  730  positioned and configured to contact at least a portion of one or more PDCs  110 , such as the superabrasive body  120 . The ionic transfer medium may include a SPE  736  and a supercritical fluid  738 . The SPE  736  may be similar or identical to the SPE  636  described herein. The SPE  736  may be shaped and positioned within the housing  150  to provide a substantially seal against the housing  150 . The SPE  736  may be spaced from the superabrasive body  120  a distance. The housing may include one or more seals, flanges, gaskets, etc. (not shown) configured to hold the SPE  736  in place and provide a seal between the SPE  736  and the housing  150 . The one or more second electrical connections  104  may be operably coupled to the SPE  736 , whereby a potential (e.g., a negative potential) may be introduced to ionic transfer assembly  700  at the one or more second electrical connections  104  upon activation. 
     The supercritical fluid  738  may be disposed between the SPE  736  and the superabrasive body  120  in the housing  150 . While the ionic transfer assembly  700  is inactive, the supercritical fluid  738  may be in a non-supercritical state, such as in a liquid or gaseous state until supercritical conditions are induced. The supercritical fluid  738  may include a fluid, such as any electrolyte solution disclosed herein, in any concentration or pH disclosed herein. The supercritical fluid  738  or method of making or using the same may include any of the supercritical fluids, individual components thereof (e.g., supercritical fluid component, aqueous component, leaching agent, or chelating agent), or methods of making or using the same disclosed in U.S. patent application Ser. No. 14/520,188, the disclosure of which is incorporated herein, by this reference, in its entirety. For example, the supercritical fluid  738  may include one or more of carbon dioxide, water, methane, ethane, propane, ethylene, propylene, methanol, ethanol, acetone, pentane, butane, hexamine, heptane, sulfur hexafluoride, xenon dichlorodifluoromethane, trifluoromethane, isopropanol, nitrous oxide, ammonia, methylamine, diethyl ether, hydrofluoric acid, nitric acid, hydrochloric acid, aqua regia, one or more chelating agents, or combinations of any of the foregoing in any concentration, ratio, pressure, temperature, or pH disclosed. Upon elevation of temperature and/or pressure of the ionic transfer assembly  700 , the supercritical fluid  738  may be brought to a supercritical state whereby ionic transport (between the superabrasive body  120  and the negative potential at the SPE  736 ) may be effectuated therethrough. The first and second electrical connections  102  and  104  may be activated (e.g., electrically biased) to provide a positive and negative potential, respectively. Upon activation of the first and second electrical connections  102  and  104 , and inducing a supercritical fluid state in the supercritical fluid  738 ; oxidation of at least some of the interstitial constituents in the superabrasive body  120  may occur. Further, ionic transport of the oxidized interstitial constituents through the supercritical fluid  738  (e.g., via electrochemical gradient therein) may transport the oxidized interstitial constituent out of the superabrasive body  120 . 
     In an embodiment, creating or providing the supercritical state may include changing (e.g., raising) one or more of the temperature or pressure of the ionic transfer assembly  700  or portions thereof (e.g., supercritical fluid  738  containing portion of the housing  150 ) from an ambient state. Supercritical conditions may be created by application of elevated heat and/or pressure to or within the housing  150 . The elevated heat and/or pressure necessary to bring the supercritical fluid  738  to a supercritical state may be dependent upon the components of the supercritical fluid  738 . In an embodiment, changing the temperature of the ionic transfer assembly includes changing the temperature of substantially only the supercritical fluid  738  containing portion of the housing  150 . For example, the housing  150  may include one or more substantially adiabatic portions adjacent to the substrate  112  and the SPE  736 , such that heating may be localized in the supercritical fluid, such as by an induction coil adjacent thereto. The housing  150  may include a cap or seal (not shown) at one or more ends thereof, which may additionally seal the contents of the housing  150  therein. 
       FIG. 8  is a flow diagram of a method  800  of removing interstitial constituents from a PDC including a superabrasive body. As explained in more detail below, the method  800  may include an act  810  of providing an ionic transfer assembly, an act  820  of applying a voltage between the first and second electrical connections and an act  830  of removing at least some of the oxidized at least one interstitial constituent from the PDC through the ionic transfer medium. 
     The method  800  may include the act  810  of providing an ionic transfer assembly. The ionic transfer assembly or any component thereof may be configured similar or identical to any ionic transfer assembly or component thereof disclosed herein. For example, the ionic transfer medium may be configured similar or identical to any ionic transfer medium disclosed herein. In an embodiment, the ionic transfer assembly may include a first electrical connection operably coupled to a PDC having a superabrasive body including a plurality of bonded superabrasive grains and at least one interstitial constituent therebetween. The ionic transfer assembly may include an ionic transfer medium configured to be in electrical and/or chemical communication with the PDC along at least one surface therebetween. The ionic transfer assembly may further optionally include an ionic reservoir in electrical and chemical communication with the ionic transfer medium and separated from the PDC by the ionic transfer medium, the ionic reservoir including a second electrical connection operably coupled thereto and configured to apply a voltage to the ionic reservoir. In an embodiment, the ionic reservoir may be configured as a portion of the ionic transfer medium, such as a portion remote from the surface thereof in contact with the PDC  110 . 
     The method  800  may include the act  820  of applying a voltage between the first and second electrical connections. For example, doing so may cause at least some of the at least one interstitial constituent to oxidize. The act  820  may include inducing a positive potential at the first electrical connection and a negative potential at the second electrical connection. The voltage between the first and second electrodes may include any voltage disclosed herein or any other suitable voltage. In an embodiment, applying a voltage between the first and second electrical connections may be carried out for a specific duration, such as any duration disclosed herein or any other suitable duration. The act of applying voltage may include applying any voltage and/or current disclosed herein, for any duration disclosed herein. Applying voltage may include electrically oxidizing one or more interstitial constituents present in a polycrystalline diamond table. 
     The method  800  may include the act  830  of removing at least some of at least one interstitial constituent from the PDC through the ionic transfer medium. In an embodiment, removing at least some of the at least one interstitial constituent from the PDC through the ionic transfer medium may include providing an ionic transfer medium configured (e.g., having pore size, ionic affinity, thickness, etc.) to transport a specific interstitial constituent therethrough. For example, removing at least some of the oxidized at least one interstitial constituent from the PDC through the ionic transfer medium may be performed substantially simultaneously with applying a voltage between the first and second electrical connections. In an embodiment, at least one interstitial constituent may be oxidized and may be removed from the PDC by removing at least some of the interstitial constituent(s) from at least a portion of the superabrasive body adjacent to one or more of the upper surface, the chamfer, and/or the lateral surface. In an embodiment, removing at least some of the at least one interstitial constituent from the PDC includes applying a negative electrical potential (e.g., charge) to an electrolyte solution (e.g., acidic solution) in the ionic reservoir. In an embodiment, the electrolyte solution may include an acidic solution of any concentration disclosed herein, For example, the electrolyte solution may include a slightly acidic citric acid/citrate solution. The method may include moving the oxidized one or more interstitial constituents through a selective ionic transfer medium (e.g., ionic bridge) in contact with the polycrystalline diamond table, such as via one or more of an electrical bias and/or ionic or chemical gradient. The method includes receiving the one or more oxidized interstitial constituents in an ionic reservoir in chemical communication with the selective ionic transfer medium. 
     In an embodiment, providing an ionic transfer assembly may include an act of positioning the PDC in the ionic transfer assembly. In an embodiment, providing an ionic transfer assembly may include an act of positioning the PDC in any of the ionic transfer mediums herein to form a contact surface similar or identical to any of those disclosed in  FIGS. 2A-2G . The PDC may include a superabrasive material (e.g., PCD body or table) having one or more of an upper surface, an interfacial surface, and a lateral surface therebetween. Optionally, the PDC may include a chamfer extending between the upper surface and the lateral surface. In an embodiment, the first electrical connection may be disposed on a portion of the superabrasive body and the superabrasive body may contact the ionic transfer medium along a contact surface therebetween. In some embodiments, the PDC may include a substrate (e.g., cemented tungsten carbide) bonded to the superabrasive body. In an embodiment, the PDC may include a polycrystalline diamond compact having a polycrystalline diamond body bonded to a tungsten carbide substrate. In an embodiment, the first electrical connection may be disposed on a portion of the substrate and the polycrystalline diamond body may contact the ionic transfer medium along at least one surface such that the polycrystalline diamond body is in electrical and/or chemical communication therewith. In an embodiment, positioning the PDC in the ionic transfer assembly includes positioning at least a portion of one or more of the upper surface, the lateral surface, and/or the chamfer in contact with the ionic transfer medium effective to create the contact or communication (e.g., electrical and/or chemical communication) therebetween. In an embodiment, positioning the PDC in the ionic transfer assembly includes positioning only a portion of at least one of the upper surface, the lateral surface, and/or the chamfer in contact with the ionic transfer medium. 
     Thus, the embodiments of workpieces (e.g., superabrasive compacts such as PDCs and/or PCDs) disclosed herein or formed by the leaching processes disclosed herein may be used in any apparatus or structure in which at least one conventional PDC is typically used. In one embodiment, a rotor and a stator, assembled to form a thrust-bearing apparatus, may each include one or more PCD elements and/or PDCs leached according to any of the embodiments disclosed herein and may be operably assembled to a downhole drilling assembly. U.S. Pat. Nos. 4,410,054; 4,560,014; 5,364,192; 5,368,398; and 5,480,233, the disclosure of each of which is incorporated herein, in its entirety, by this reference, disclose subterranean drilling systems within which bearing apparatuses utilizing the superabrasive elements and/or superabrasive compacts disclosed herein may be incorporated. The embodiments of superabrasive bodies and/or superabrasive compacts disclosed herein may also form all or part of heat sinks, wire dies, bearing elements, cutting elements, cutting inserts (e.g., on a roller-cone-type drill bit), machining inserts, or any other article of manufacture as known in the art. Other examples of articles of manufacture that may use any of the superabrasive bodies and/or superabrasive compacts disclosed or leached by the methods herein are disclosed in U.S. Pat. Nos. 4,811,801; 4,268,276; 4,468,138; 4,738,322; 4,913,247; 5,016,718; 5,092,687; 5,120,327; 5,135,061; 5,154,245; 5,180,022; 5,460,233; 5,544,713; and 6,793,681, the disclosure of each of which is incorporated herein, in its entirety, by this reference. 
     While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting. Additionally, the words “including,” “having,” and variants thereof (e.g., “includes” and “has”) as used herein, including the claims, shall be open ended and have the same meaning as the word “comprising” and variants thereof (e.g., “comprise” and “comprises”).