Patent Publication Number: US-2016230471-A1

Title: Polycrystalline diamond compacts with partitioned substrate, polycrystalline diamond table, or both

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/452,206 filed on 5 Aug. 2014, which is a continuation of U.S. patent application Ser. No. 13/234,252 filed on 16 Sep. 2011 (now U.S. Pat. No. 8,950,519), which is a continuation-in-part of U.S. patent application Ser. No. 13/116,566 filed 26 May 2011 (now U.S. Pat. No. 8,863,864) and a continuation-in-part of U.S. patent application Ser. No. 13/166,007 filed 22 Jun. 2011 (now U.S. Pat. No. 9,062,505). Each of the foregoing applications is incorporated herein, in its entirety, by this reference. 
    
    
     BACKGROUND 
     Wear-resistant, polycrystalline diamond compacts (“PDCs”) are utilized in a variety of mechanical applications. For example, PDCs are used in drilling tools (e.g., cutting elements, gage trimmers, etc.), machining equipment, bearing apparatuses, wire-drawing machinery, and in other mechanical apparatuses. 
     PDCs have found particular utility as superabrasive cutting elements in rotary drill bits, such as roller-cone drill bits and fixed-cutter drill bits. A PDC cutting element typically includes a superabrasive diamond layer commonly known as a diamond table. The diamond table is formed and bonded to a substrate using a high-pressure/high-temperature (“HPHT”) process. The PDC cutting element may be brazed directly into a preformed pocket, socket, or other receptacle formed in a bit body. The substrate may often be brazed or otherwise joined to an attachment member, such as a cylindrical backing. A rotary drill bit typically includes a number of PDC cutting elements affixed to the bit body. It is also known that a stud carrying the PDC may be used as a PDC cutting element when mounted to a bit body of a rotary drill bit by press-fitting, brazing, or otherwise securing the stud into a receptacle formed in the bit body. 
     Conventional PDCs are normally fabricated by placing a cemented 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 an HPHT press. The substrate(s) and volume(s) of diamond particles are then processed under HPHT conditions in the presence of a catalyst material that causes the diamond particles to bond to one another to form a matrix of bonded diamond grains defining a polycrystalline diamond (“PCD”) table. The catalyst material is often a metal-solvent catalyst (e.g., cobalt, nickel, iron, or alloys thereof) that is used for promoting intergrowth of the diamond particles. 
     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 acts as a catalyst to promote intergrowth between the diamond particles, which results in formation of a matrix of bonded diamond grains having diamond-to-diamond bonding therebetween, with interstitial regions between the bonded diamond grains being occupied by the solvent catalyst. Once the PCD table is formed, the solvent catalyst may be at least partially removed from the PCD table of the PDC by acid leaching. 
     SUMMARY 
     Various embodiments of the present invention are directed to methods of relieving residual stresses within a PCD table of a PDC. At least partial relief of such stresses reduces the tendency of the PCD table (which may be relatively brittle) to crack or otherwise fracture during use as a result of an impact or similar event. According to an embodiment of a method, a PDC including a PCD table bonded to a substrate (e.g., tungsten carbide or other carbide substrate) is provided. The PCD table includes a plurality of diamond grains that are bonded together. In order to at least partially relieve stress, the PCD table, the substrate, or both are partitioned (e.g., by EDM cutting, laser cutting, grinding, etc.). 
     Other embodiments are directed to associated PDCs that include a stress relieving partition formed into at least one of the substrate or PCD table. Such a PDC may include a substrate, a PCD table including a plurality of bonded diamond grains in which the PCD table is bonded to the substrate. The PCD table includes an exterior working surface and at least one lateral surface. At least one stress relieving partition is formed into at least one of the substrate or the PCD table to at least partially relieve stress within the PCD table. 
     The inventors have discovered that such partitioning of at least one of the PCD table or substrate decreases the residual stress within the PCD table, providing improved durability. In addition, partitioning of the PCD table provides a boundary that can stop propagation of a crack within the PCD table, should a crack form. Stopping progression of such a crack allows damage to be limited to and contained within one portion of the PCD table, preventing it from spreading to other portions across the partition. 
     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 invention, wherein identical reference numerals refer to identical or similar elements or features in different views or embodiments shown in the drawings. 
         FIG. 1  is an isometric view of an example PDC; 
         FIG. 2  is a flow diagram describing an embodiment of a method for partitioning a substrate, PCD table, or both of a PDC in order to relieve residual stresses within the PCD table; 
         FIG. 3  is an isometric view of a PDC including a partitioning cut formed into the PCD table according to an embodiment; 
         FIGS. 3A-3C  are cross-sectional views of PDCs including a partition formed into the PCD table and in which the respective partitioning cuts extend to different lengths relative to the location of an interface between the PCD table and the substrate according to various embodiments; 
         FIG. 3D  is an isometric view of a PDC including a domed PCD layer including partitioning cuts formed into the domed PCD table; 
         FIGS. 4A-4C  are top plan views of PDCs similar to that shown in  FIG. 3 , but including different partition configurations according to various embodiments; 
         FIGS. 5A-5D  are cross-sectional views of PDCs including a partition formed into the substrate and in which the respective partitioning cuts extend to different lengths relative to the location of an interface between the substrate and the PCD table according to various embodiments; 
         FIG. 6  is a graph showing residual stresses for PCD tables as a result of various partitioning configurations; 
         FIGS. 7A-7C  are isometric views of various embodiments of PDCs including a spring mechanism formed into the substrate of the PDC in order to increase the ability of the adjacent PCD table to flex and absorb energy as a result of an impact; 
         FIG. 7D  is a cross-sectional view of another embodiment of a PDC including a spring mechanism disposed within the substrate of the PDC; 
         FIG. 8  is an isometric view of an embodiment of a rotary drill bit that may employ one or more PDCs according to any of the disclosed embodiments; 
         FIG. 9  is a top elevation view of the rotary drill bit shown in  FIG. 8 ; 
         FIG. 10  is an isometric cut-away view of an embodiment of a thrust-bearing apparatus that may employ one or more PDCs according to any of the disclosed embodiments; 
         FIG. 11  is an isometric cut-away view of an embodiment of a radial bearing apparatus that may employ one or more PDCs according to any of the disclosed embodiments; and 
         FIG. 12  is a schematic isometric cut-away view of an embodiment of a subterranean drilling system including the thrust-bearing apparatus shown in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     I. Introduction 
     Embodiments of the present invention are directed to PDCs including a substrate, and a PCD table including a plurality of bonded diamond grains that is bonded to the substrate. The PCD table includes an exterior working surface and at least one lateral surface. At least one stress relieving partition is formed into the substrate, the PCD table, or both to at least partially relieve stress within the PCD table. At least partial relief of the residual stresses of the PCD table improves the overall durability of the PCD table. Further embodiments of the present invention are directed to related methods of fabricating such PDCs including one or more stress relieving partitions formed into the substrate, PCD table, or both. 
     II. PDC Embodiments 
     The PCD elements partitioned for at least partial stress relief disclosed herein include PCDs fabricated according to one-step and two-step methods, as discussed in more detail hereinbelow. It may also be possible to form a partition into a freestanding PCD table or substrate, prior to final bonding of the two together. A one-step PDC may include a PCD table integrally formed and bonded to a cemented carbide substrate. The PCD table includes directly bonded-together diamond crystals exhibiting diamond-to-diamond bonding (e.g., sp 3  bonding) therebetween that define a plurality of interstitial regions. An example PDC  100  including a PCD table  102  and a cemented carbide substrate  104  is shown in  FIG. 1 . The PCD table  102  includes at least one lateral surface  105 , an upper exterior working surface  103 , and may include an optional chamfer  107  formed therebetween. It is noted that at least a portion of the at least one lateral surface  105  and/or the chamfer  107  may also function as a working surface (e.g., that contacts a subterranean formation during drilling operations). 
     A metal-solvent catalyst (e.g., iron, nickel, cobalt, or alloys thereof) is disposed in at least a portion of the interstitial regions between adjacent diamond crystals of PCD table  102 . The cemented carbide substrate  104  may comprise tungsten carbide, tantalum carbide, vanadium carbide, niobium carbide, chromium carbide, titanium carbide, or combinations of the foregoing carbides cemented with iron, nickel, cobalt, or alloys of the foregoing metals. For example, the cemented carbide substrate may comprise cobalt-cemented tungsten carbide. 
     Generally, a one-step PDC may be formed by placing un-bonded diamond particles adjacent to a cemented carbide substrate and subjecting the diamond particles and the cemented carbide substrate to an HPHT process under diamond stable HPHT conditions. During the HPHT process, metal-solvent catalyst from the cemented carbide substrate at least partially melts and sweeps into interstitial regions between the diamond crystals to catalyze growth of diamond and formation of diamond-to-diamond bonding between adjacent diamond particles so that a PCD table is formed that bonds to the cemented carbide substrate upon cooling from the HPHT process. 
     A two-step PDC may also be formed in which an at least partially leached PCD table (i.e., a freestanding PCD table) may be placed adjacent to a cemented carbide substrate and subjected to an HPHT process under diamond stable conditions. During the HPHT process, an infiltrant from the cemented carbide substrate infiltrates into the interstitial regions of the at least partially leached PCD table and bonds the infiltrated PCD table to the cemented carbide substrate upon cooling from the HPHT process. 
     In an embodiment, the at least partially leached PCD table may be formed by separating the PCD table from a one-step PDC by removing the cemented carbide substrate via any suitable process (e.g., grinding, machining, laser cutting, EDM cutting, or combinations thereof). The metal-solvent catalyst present within the PCD table may be leached from the PCD table in a suitable acid. In another embodiment, the at least partially leached PCD table may be formed by other methods, such as sintering diamond particles in the presence of a metal-solvent catalyst to form a PCD table or disk and leaching the PCD table in a suitable acid. 
     After bonding to a final substrate, both one-step and two-step PDCs may be subjected to a leaching process to remove a portion of the metal-solvent catalyst or infiltrant from the PCD table to a selected depth and from one or more exterior surfaces. Removal of the metal-solvent catalyst or infiltrant may help improve thermal stability and/or wear resistance of the PCD table during use. 
     Examples of acids used in leaching include, but are not limited to, aqua regia, nitric acid, hydrofluoric acid, and mixtures thereof. For example, leaching the PCD table  102  may form a leached region that extends inwardly from the exterior surface  103 , the lateral surface  105 , and the chamfer  107  to a selected leached depth. Such a selected leached depth may be about 100 μm to about 1000 μm, about 100 μm to about 300 μm, about 300 μm to about 425 μm, about 350 μm to about 400 μm, about 350 μm to about 375 μm, about 375 μm to about 400 μm, about 500 μm to about 650 μm, or about 650 μm to about 800 μm. 
     The bonded together diamond grains of the PCD table may exhibit an average grain size of about 100 μm or less, about 40 μm or less, such as about 30 μm or less, about 25 μm or less, or about 20 μm or less. For example, the average grain size of the diamond grains may be about 10 μm to about 18 μm, about 8 μm to about 15 μm, about 9 μm to about 12 μm, or about 15 μm to about 25 μm. In some embodiments, the average grain size of the diamond grains may be about 10 μm or less, such as about 2 μm to about 5 μm or submicron. 
     The diamond particle size distribution of the diamond particles may exhibit a single mode, or may be a bimodal or greater grain size distribution. In an embodiment, the diamond particles of the one or more layers of diamond particles may comprise 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 (by any suitable method) that differ by at least a factor of two (e.g., 30 μm and 15 μm). According to various embodiments, the diamond particles may include a portion exhibiting a relatively larger average particle size (e.g., 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., 6 μm, 5 μm, 4 μm, 3 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 diamond particles may include a portion exhibiting a relatively larger average particle size between about 10 μm and about 40 μm and another portion exhibiting a relatively smaller average particle size between about 1 μm and 4 μm. In some embodiments, the diamond particles may comprise 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. 
     It is noted that the as-sintered diamond grain size may differ from the average particle size of the diamond particles prior to sintering due to a variety of different physical processes, such as grain growth, diamond particles fracturing, carbon provided from another carbon source (e.g., dissolved carbon in the metal-solvent catalyst), or combinations of the foregoing. 
     The PCD table  102  may exhibit a thickness of at least about 0.040 inch, such as about 0.045 inch to about 1 inch, about 0.045 inch to about 0.500 inch, about 0.050 inch to about 0.200 inch, about 0.065 inch to about 0.100 inch, or about 0.070 inch to about 0.100 inch (e.g., about 0.09 inch). 
     As described above, the PCD table  102  may be formed separately from or integral with the substrate  104  in an HPHT process. When formed separately, the PCD table  102  may be subsequently attached to the substrate  104  in another HPHT process (i.e., the PCD is fabricated in a two-step process). The temperature of such HPHT processes may typically be at least about 1000° C. (e.g., about 1200° C. to about 1600° C.) and the pressure of the HPHT process may typically be at least about 4.0 GPa (e.g., about 5.0 GPa to about 12.0 GPa, about 7.0 GPa to about 9.0 GPa, about 6.0 GPa to about 8.0 GPa, or about 9.0 GPa to about 12.0 GPa). Techniques for brazing the PCD table to the substrate are disclosed in U.S. application Ser. No. 11/545,929, which incorporated by reference below. 
     Additional details of examples of one-step and two-step processes for fabricating a PDC are disclosed in U.S. application Ser. No. 12/961,787 filed 7 Dec. 2010; U.S. application Ser. No. 11/545,929 filed 10 Oct. 2006; and U.S. Pat. No. 7,866,418 issued on 11 Jan. 2011, both of which are incorporated herein, in their entirety, by this reference. Any PDC or PCD table disclosed in U.S. application Ser. No. 12/961,787; U.S. application Ser. No. 11/545,929; and U.S. Pat. No. 7,866,418 may be used as the initial PDC or PCD table that is partitioned. 
     III. Embodiments of Partitioned PDCs and Fabrication Methods 
       FIG. 2  shows a flow diagram generally describing an embodiment of a method S 10  for at least partially relieving residual stresses within a PCD table of the PDC. At S 12 , a PDC including a PCD table bonded to a substrate is provided. The PCD table includes a plurality of diamond grains that are bonded together. The PDC may be similar to that shown in  FIG. 1 . Because of differences between the coefficient of thermal expansion (“CTE”) of the substrate relative to that of the PCD table, inherent residual stresses are present within the PDC structure. At least a portion of the residual stresses can be relieved by forming a partition (e.g., a cut) into the PCD table, the substrate, or both. At S 14 , such a partition is formed into the PCD table, the substrate or both. The modified PDC including one or more partitions exhibits a decreased level of residual stress within the PCD table, which may improve the durability and usability of the PDC, even if it is damaged during use. For example, the partition can arrest or direct propagation of a crack in the PCD table at the partition should a crack form during use. 
       FIG. 3  is an isometric view of a PDC  200  including a partition  208  formed into PCD table  102 . The partitioning cut  208  is shown as being generally aligned with a diameter of the PCD table  102 , partitioning table  102  into two substantially equal portions  102   a  and  102   b . The partitioning cut  208  is shown as extending nearly to interface  110  between the substrate  104  and the PCD table  102  (e.g., leaving a PDC table thickness of less than about 0.1 inch). The partitioning cut  208  may be disposed entirely within PCD table  102  (as shown), may extend to the interface  110 , or may even extend somewhat past the interface  110  into the substrate  104 . 
     Extension of the partitioning cut  208  beyond the interface  110  may be beneficial where the PCD table  102  has been sintered with the substrate  104  to at least partially relieve stresses associated with a zone of the substrate  104  adjacent interface  110  that is depleted of metal-solvent catalyst relative to adjacent deeper portions of the substrate  104 . The metal-solvent catalyst depletion zone may be more brittle than adjacent regions in the substrate including higher cobalt or other metal solvent catalyst levels. As a result, the cut  208  may advantageously extend into or past such a depletion zone. For example, during sintering and bonding, a metal-solvent catalyst or infiltrant is swept into the region of the PCD table  102 , thereby depleting a portion of the substrate  104  of cobalt or other metal-solvent catalyst/infiltrant that is disposed adjacent to the interface  110 . The partitioning cut  208  may be extended into a depletion zone or past this zone of the substrate  104  to better relieve stresses resulting from the presence of the depleted zone adjacent the PDC table  102 . 
     Where the partitioning cut  208  extends short of the interface  110  (so as to be entirely disposed within PCD table  102 ), the partitioning cut  208  may leave a PCD table thickness between greater than 0 and about 0.1 inch, between about 0.005 inch and about 0.07 inch, or between about 0.05 inch and about 0.1 inch.  FIG. 3A  shows an embodiment in which the portioning cut  208  is entirely disposed within the PCD table  102 , leaving a PCD thickness as described above.  FIG. 3B  shows an embodiment in which the portioning cut  208  extends to the interface  110 .  FIG. 3C  shows an embodiment in which the portioning cut  208  extends beyond the interface  110 , into the substrate  104 . 
     Where the partitioning cut  208  extends through PCD table  102  and into substrate  104  (e.g., into or even deeper than a depletion zone), the partitioning cut  208  may extend between greater than 0 and about 0.1 inch into substrate  104 , between about 0.005 inch and about 0.07 inch into substrate  104 , or between about 0.008 inch and about 0.1 inch into substrate  104 . In an embodiment, a depletion zone may typically extend to a depth between about 0.008 inch to about 0.05 inch. 
     The width of partitioning cut  208  may be of any desired value. In one embodiment, the partitioning cut  208  may be formed by EDM or laser cutting. The width of the partitioning cut  208  may be about 0.001 inch to about 0.2 inch, about 0.005 inch to about 0.05 inch, about 0.01 inch to about 0.1 inch, about 0.0001 to about 0.001 inch, or less than about 0.001 inch. 
       FIG. 3D  is an isometric view of a PDC  200 ′ including a substrate  104 ′ bonded to a PCD layer  102 ′ with a convexly-curved top working surface  103 ′. As with the illustrated planar PCD table configurations, the substrate, PCD layer, or both of such a PDC may be partitioned to at least partially relieve stresses. In an embodiment, a plurality of partitioning cuts  208 ′ may be formed about a periphery of the PCD layer  102 ′ proximate to the interface surface  110 ′ between the PCD layer  102 ′ and the substrate  104 ′. Such domed or otherwise curved PCD layers may particularly benefit from partitioning, as such PDCs may exhibit greater internal stresses than planar PCD tables, which can lead to delamination or other premature failure of the PCD layer. As illustrated, the partitioning cuts  208 ′ may be formed into the convexly-curved top working surface  103 ′ of the PCD layer  102 ′. For example, the one or more partitioning cuts  208 ′ may terminate at the interfacial surface  110 ′ or may extend beyond the interfacial surface  110 ′ into the substrate  104 ′ (shown with the broken lines). 
       FIGS. 4A-4C  illustrate top plan views of various embodiments of configurations by which PCD table  102  may be partitioned.  FIG. 3  illustrates an embodiment where a single partitioning cut  208  divides the PCD table  102  into the two portions  102   a ,  102   b .  FIG. 4A  illustrates an embodiment where the PCD table  102  is partitioned into four substantially equal portions  302   a - 302   d . Two partitioning cuts  308  may be formed in a top surface of PCD table  102 , along the diameter of PCD table  102  so as to intersect substantially perpendicularly.  FIG. 4B  illustrates an embodiment where the PCD table  102  is partitioned into three substantially equal portions  402   a - 402   c  where three partitioning cuts  408  are spaced about 120° apart. Each cut  408  is located at a radius of PCD table  102 , each spaced about 120° apart.  FIG. 4C  shows another embodiment similar to that of  FIG. 4B , but in which a central generally circular partitioning cutting cut  508   c  is also formed. The radius partitioning cuts  508  do not extend to the center of PCD table  102 , but end at the intersection with central generally circular cut  508   c . The generally circular partitioning cutting cut  508   c  defines a central portion  502   d , while the other partitioning cuts  508  further define boundaries of portions the  502   a - 502   c . As described above, partitioning of the PCD table  102  may extend short of the interface  110 , to the interface  110 , or beyond the interface  110  and into the substrate  104  (e.g., past a depleted zone). In an embodiment, the PCD table may be completely partitioned (e.g., the cuts may extend to the interface  110 ), and the PCD table may subsequently be bonded back together (e.g., by HPHT processing with an associated substrate). Alternative partitioning configurations are possible, e.g., along various radius positions similar to the embodiment shown in  FIG. 3D . For example, the partitioning cut(s) may not be disposed along a radius or diameter, but offset so as to divide the partitioned component into portions of any desired size or shape. The illustrated configurations are only embodiments, and various other partitioning configurations may be employed. 
       FIGS. 5A-5C  illustrate cross-sectional views of various configurations by which the substrate of PDC  100  may be partitioned. The substrate may be partitioned in any configuration desired, for example, similar to the two, three, or four portions shown with respect to partitioning of PCD table  102  in  FIGS. 3 and 4A-4C . Of course, other partitioning configurations will also be apparent to one of skill in the art. As with partitioning the PCD table  102 , partitioning of the substrate  104  may extend to the interface  110 , short of the interface  110 , or extend past interface the  110  (i.e., into the PCD table  102 ).  FIG. 5A  shows a partitioning cut  608  of the substrate  104  terminating generally at the interface  110  between the substrate  104  and the PCD table  102  according to an embodiment.  FIGS. 5B and 5C  both show configurations in which the partitioning cut  608  terminates short of the interface  110  so that the entirety of the partitioning cut  608  is disposed within substrate the  104  according to an embodiment.  FIG. 5D  shows an example in which partitioning cut  608  extends beyond the interface  110 , into the PCD table  102 . In addition, although the interface  110  is shown in the various Figures as being generally planar, this is not required. For example, the interface  110  may be non-planar (e.g., curved, having a plurality of projections, having a plurality of recesses, or combinations of the foreging), or may provide for varying thickness of the adjacent substrate, PCD table, or both. Of course, additional partitioning cuts may be formed in the PCD table  102 , if desired (e.g., as shown in  FIGS. 3 and 4A-4C ), so that both the substrate and PCD table are partitioned. Furthermore, when partitioning the exterior surfaces of both the substrate  104  and the PCD table  102 , the partitions may be offset relative to one another so as to not intersect one another for increased strength. 
     Where the partitioning cut  608  extends short of the interface  110  so as to be entirely disposed within substrate  104 , the partitioning cut  608  may leave a substrate thickness between about 0 and about 0.1 inch, between about 0.005 inch and about 0.07 inch, or between about 0.05 inch and about 0.1 inch. By way of example,  FIG. 5B  may represent a partitioning cut  608  that extends to within about 0.01 inch (e.g., about 0.01 inch or less) from the interface  110 .  FIG. 5C  may represent a partitioning cut  608  that extends to within about 0.05 inch (e.g., about 0.05 inch or less) from the interface  110 . 
     The partitioning cuts may be formed by any suitable technique, including, but not limited to, grinding, machining, laser cutting, electro-discharge machining (“EDM”), combinations thereof, or other suitable technique. Suitable EDM techniques includes plunge EDM, wire EDM, or combinations thereof, without limitation. The foregoing material removal techniques remove a selected amount of material from the substrate  104 , the PCD table  102 , or both, to form the portioning cut with a desired depth and width. Typical widths for the partitioning cut  608  may be about 0.001 inch to about 0.2 inch, about 0.005 inch to about 0.05 inch, about 0.01 inch to about 0.1 inch, about 0.0001 to about 0.001 inch, or less than about 0.001 inch. When partitioning a PCD table that has been leached, it may be desirable to form the partitioning cuts by laser cutting, which does not require that the PCD table be electrically conductive. Additional details relative to laser cutting embodiments are disclosed in U.S. patent application Ser. No. 13/166,007 filed Jun. 22, 2011 and entitled METHOD FOR LASER CUTTING POLYCRYSTALLINE DIAMOND STRUCTURES, which is incorporated herein, in its entirety, by this reference. 
       FIG. 6  shows actual testing data associated with partitioning cuts  608  similar to those shown in  FIGS. 5A-5C , in which the substrate is partitioned. As shown, a standard PDC including no partitioning cuts exhibits residual stress values within the PCD table that are quite variable depending on the thickness of the substrate. The residual stress data is calculated by measuring the strain relieved in the PCD table as the substrate is progressively ground away. Stress may be calculated from the measured relieved strain values assuming a modulus of elasticity (E) of 1.24×10 8  psi and a Poisson&#39;s ratio (ν) of 0.23 for the PCD table. Such a technique is described in Lin, T. P., Hood, M., Cooper, G. A., &amp; Smith, R. H. (1994). Residual stresses in polycrystalline diamond compacts.  Journal of the American Ceramic Society,  77, 1562-1568, which is incorporated herein, in its entirety, by this reference. For example, in a conventional PDC without partitioning (e.g., the PDC  100  of  FIG. 1 ) a peak tensile residual stress within the PCD table of about 5.00×104 psi is found at a substrate thickness of about 0.06 inch. As the substrate thickness increases, the residual stress values drop, eventually reaching a maximum compressive residual stress of about 6.00×10 4  psi. 
     When the substrate is partitioned (e.g., as shown in  FIG. 5A ) generally to the PCD table-substrate interface, the residual stress profile as a function of substrate thickness is very different from the standard PDC. The residual stress is tensile in character no matter the thickness of the substrate, and is relatively constant, remaining between about 0.5×10 4  psi to about 1×10 4  psi. When the substrate is partitioned (e.g., as shown in  FIG. 5B ) to a distance about 0.01 inch from the PCD table-substrate interface, the residual stress profile is similar, although somewhat higher. The residual stress is tensile in character no matter the substrate thickness, and is relatively constant, remaining between about 1×10 4  psi to about 1.75×10 4  psi. When the substrate is partitioned (e.g., as shown in  FIG. 5C ) to a distance about 0.05 inch from the PCD table-substrate interface, the residual stress profile is again similar, although higher still. The residual stress is still tensile in character no matter the substrate thickness, and is relatively constant, remaining between about 4×10 4  psi to about 4.5×10 4  psi. 
     As shown in  FIGS. 7A-7C , some embodiments may further include a spring mechanism  112  within substrate  104  to allow the adjacent PCD table  102  to flex and better absorb energy as a result of an impact. Various spring mechanisms  112  may be formed into substrate  104  by removal of select portions of substrate  104 .  FIG. 7A  shows an embodiment of a PDC  700  including a PCD table  102  that has been partitioned by two substantially perpendicular diameter cuts  708  (i.e., similar to that shown in  FIG. 4A ). A substrate  104  is bonded to the PCD table  102  at the interface  110 . The spring mechanism  112  includes a plurality of generally longitudinally extending (i.e., vertical in the orientation of  FIG. 7A ) relief cuts  114 , which may be similar to partitioning cuts  608  described above. Such relief cuts  114  may typically not extend the full width of substrate  104 , but be formed in an outer peripheral surface and extend partially into the substrate  104  to a selected depth. While such relief cuts  114  may also provide stress relief as described above relative to the partitioning cuts  608 , the relief cuts  114  may provide a spring mechanism within the substrate  104  for improved impact resistance for the PCD table  102 . The cuts  114  may be formed to any desired depth, and may extend towards the center of PDC  100 , defined along longitudinal axis A (e.g., cuts  114  may be formed along radius lines extending outward from axis A). According to an embodiment, formation of the spring mechanism  112  may be accomplished by bonding a solid backup substrate portion to a partitioned substrate portion. Providing a solid backup substrate portion may add strength to the substrate and may be formed from any of the cemented carbide materials disclosed herein.  FIG. 7A  illustrates one such embodiment, where the substrate  104  includes a solid backup bottom portion  104   a  and a partitioned top portion  104   b . The two portions  104   a  and  104   b  may be bonded together along interface  110   a  via brazing, diffusion bonding, or an HPHT bonding process. 
       FIG. 7B  shows another embodiment of a configuration  700 ′ similar to the PDC  700  shown in  FIG. 7A , but in which the spring mechanism  112 ′ comprises a helically extending groove  116  extending around a periphery (e.g., a circumference) of the substrate  104 . The height “H” and depth “D” of the helical groove  116  may be selected depending on desired spring characteristics. For example, the depth “D” may be about 0.01 to about 0.5 times a diameter or other lateral dimension of the PDC  700 ′, such as about 0.02 cm to about 1 cm, or about 0.6 cm to about 0.8 cm. The height “H” may be about 0.001 inch to about 0.2 inch, about 0.005 inch to about 0.05 inch, or about 0.01 inch to about 0.1 inch.  FIG. 7C  shows another embodiment of a configuration  700 ″ similar to the PDC  100  shown in  FIG. 7B , but in which the spring mechanism  112 ″ comprises a groove  118  that is not helical, but extends around the substrate  104  at a substantially constant distance from the interface  110 . 
     As seen in  FIGS. 7A-7C , the spring mechanism may be provided adjacent to the interface  110 . The spring mechanism may extend substantially the full height of the substrate  104 , or (as shown), may be disposed within only a “top” portion of the substrate  104 , adjacent to the interface  110  so as to be disposed in close proximity to the PCD table  102 . 
     In each case, the disclosed spring mechanism  112  provides an improved ability for the adjacent PDC table  102  to flex and absorb energy as a result of an impact. In other words, a given impact that would result in fracture of the PCD table of a PDC (e.g., such as that shown in  FIG. 1 ) that does not include a spring mechanism may comparatively exhibit a different outcome when a spring mechanism (e.g., as shown in  FIGS. 7A-7C ) is included in the substrate  104 . As compared to the standard PDC, a PDC as shown in  FIGS. 7A-7C  may be expected to exhibit less of a tendency for the PCD table to fracture when subjected to a given impact. As such, the PDCs and PCD tables may exhibit increased durability. Such configurations may be particularly beneficial for drilling applications when encountering a hard rock formation. It may also be beneficial with impact loading. 
     In some embodiments, a compliant material (e.g., a rubber or other polymer such as silicone or a thermoplastic elastomer) may be disposed within the groove to provide a selected stiffness to the spring mechanism. 
     Providing both partitioning of the PCD table and a spring mechanism as shown in  FIGS. 7A-7C  may be particularly beneficial, as the partitioning of the PCD table  102  at least partially relieves stresses within the PCD table as shown in  FIG. 6 , while also limiting any damage to a PCD table to the portion in which the crack first appears. In other words, the crack may be able to propagate to the partition cut defining the boundary of the particular PCD table portion, but its progress may be arrested at this point by the presence of the partitioning cut. In addition, providing a spring mechanism as shown in  FIGS. 7A-7C  provides additional durability to inhibit a crack from forming in the first place, as the impact can be at least somewhat absorbed by the spring mechanism and the ability of the above PCD table to flex. Thus, a crack is less likely to form in the first instance, and if a crack does form (as the result of a relatively large magnitude impact), the damage caused by the crack may be limited to the portion in which it forms or directed along the partitioning cut. 
     Of course, it will be understood that a spring mechanism for improving impact resistance of the PCD table may be provided independently of any partitioning of the PCD table or substrate. For example, a spring mechanism may be provided where no partitioning is provided in the PCD table  102  or substrate  104 .  FIG. 7D  illustrates one such PDC  700 ′″ including a PCD table  702  bonded to a substrate  704 . A bottom portion of substrate  704  may be received within a cavity  710  defined by a substrate sleeve portion  706 . The substrate sleeve portion  706  may include a base portion  708  with a spring mechanism  712  disposed within the cavity  710 . For example, the spring mechanism  712  may be a compression spring and/or other biasing element such as a resilient material. 
     As illustrated, the substrate portions  704  and  706  may provide a generally flush periphery at their interface when the spring mechanism  712  is compressed. The lower portion  705  of the substrate portion  704  may be laterally smaller than the adjacent upper section of the substrate portion  704  so that the lower portion  705  may be received within the cavity  710  of the sleeve portion  706  of the substrate  704 . The internal surface of the sleeve portion  706  may include a flange surface  714  that is configured to abut against an oppositely disposed flange  716 . Abutment between the flanges  714  and  716  provides a stop, which limits how far substrate portion  704  can be biased upwards by the spring mechanism  712 . Although no partitioning cuts are shown in PCD table  702  or the substrate portion  704 , such cuts may optionally be provided. Similarly, any of the embodiments shown in  FIGS. 7A-7C  may have the partitioning cuts formed in the PCD table  102  omitted. 
     IV. Applications of Products Including PDCs 
     The PDCs including features and/or formed according to the various embodiments disclosed herein may be used as PDC cutting elements on a rotary drill bit, within thrust bearing assemblies, rotary bearing assemblies, and other applications. For example, in a method according to an embodiment of the invention, one or more PDCs that have been partitioned according to any of the disclosed embodiments may be attached to a bit body of a rotary drill bit, brazed or otherwise joined into a bearing assembly, or otherwise incorporated into a desired product. In one embodiment, partitioning cuts formed into the substrate may be at least partially filled with braze alloy or other material, e.g., when brazing or otherwise joining the PDC into a bearing assembly or other product. 
       FIG. 8  is an isometric view and  FIG. 9  is a top elevation view of an embodiment of a rotary drill bit  800  that includes at least one PDC configured and/or fabricated according to any of the disclosed PDC embodiments. The rotary drill bit  800  comprises a bit body  802  that includes radially and longitudinally extending blades  804  having leading faces  806 , and a threaded pin connection  808  for connecting the bit body  802  to a drilling string. The bit body  802  defines a leading end structure for drilling into a subterranean formation by rotation about a longitudinal axis  810  and application of weight-on-bit. At least one PDC, configured according to any of the previously described PDC embodiments, may be affixed to the bit body  802 . With reference to  FIG. 9 , each of a plurality of PDCs  812  is secured to the blades  804  of the bit body  802  ( FIG. 8 ). For example, each PDC  812  may include a PCD table  814  bonded to a substrate  816 . More generally, the PDCs  812  may comprise any PDC disclosed herein, without limitation. 
     In addition, if desired, in some embodiments, a number of the PDCs  812  may not have been partitioned as described herein. Also, circumferentially adjacent blades  804  define so-called junk slots  820  therebetween. Additionally, the rotary drill bit  800  includes a plurality of nozzle cavities  818  for communicating drilling fluid from the interior of the rotary drill bit  800  to the PDCs  812 . 
       FIGS. 8 and 9  merely depict one embodiment of a rotary drill bit that employs at least one PDC in accordance with the disclosed embodiments, without limitation. The rotary drill bit  800  is used to represent any number of earth-boring tools or drilling tools, including, for example, core bits, roller-cone bits, fixed-cutter bits, eccentric bits, bi-center bits, reamers, reamer wings, or any other downhole tool including superabrasive compacts, without limitation. 
     The PDCs including one or more partitioning cuts according to embodiments disclosed herein may also be utilized in applications other than cutting technology. For example, the disclosed PDC embodiments may be used in bearings or other articles of manufacture including at least one PCD table or compact. 
       FIG. 10  is an isometric cut-away view of an embodiment of a thrust-bearing apparatus  900 , which may utilize any of the disclosed PDC embodiments as bearing elements. The thrust-bearing apparatus  900  includes respective thrust-bearing assemblies  902 . Each thrust-bearing assembly  902  includes an annular support ring  904  that may be fabricated from a material, such as carbon steel, stainless steel, or another suitable material. Each support ring  904  includes a plurality of recesses (not labeled) that receives a corresponding bearing element  906 . Each bearing element  906  may be mounted to a corresponding support ring  904  within a corresponding recess by brazing, press-fitting, using fasteners, or another suitable mounting technique. One or more, or all of bearing elements  906  may be partitioned according to any of the disclosed embodiments. For example, each bearing element  906  may include a substrate  908  and a PCD table  910 , with the PCD table  910  including a bearing surface  912 . 
     In use, the bearing surfaces  912  of one of the thrust-bearing assemblies  902  bears against the opposing bearing surfaces  912  of the other one of the bearing assemblies  902 . For example, one of the thrust-bearing assemblies  902  may be operably coupled to a shaft to rotate therewith and may be termed a “rotor.” The other one of the thrust-bearing assemblies  902  may be held stationary and may be termed a “stator.” 
       FIG. 11  is an isometric cut-away view of an embodiment of a radial bearing apparatus  1000 , which may employ PDCs that have been partitioned according to any of the disclosed embodiments. The radial bearing apparatus  1000  includes an inner race  1002  positioned generally within an outer race  1004 . The outer race  1004  includes a plurality of bearing elements  1006  mounted thereto that have respective bearing surfaces  1008 . For such a radial bearing, the bearing surface  1008  of elements  1006  mounted to outer race  1004  may be concavely curved. The inner race  1002  also includes a plurality of bearing elements  1010  affixed thereto that have respective bearing surfaces  1012 . For such a radial bearing, the bearing surface  1012  of elements  1010  mounted to inner race  1002  may be convexly curved to mate with the concave curvature of bearing surface  1008 . One or more, or all of the bearing elements  1006  and  1010  may be partitioned according to any of the embodiments disclosed herein. The inner race  1002  is positioned generally within the outer race  1004  and, thus, the inner race  1002  and outer race  1004  may be configured so that the bearing surfaces  1008  and  1012  may at least partially contact one another and move relative to each other as the inner race  1002  and outer race  1004  rotate relative to each other during use. 
     The radial-bearing apparatus  1000  may be employed in a variety of mechanical applications. For example, so-called “roller cone” rotary drill bits may benefit from a radial-bearing apparatus disclosed herein. More specifically, the inner race  1002  may be mounted to a spindle of a roller cone and the outer race  1004  may be mounted to an inner bore formed within a cone and that such an outer race  1004  and inner race  1002  may be assembled to form a radial-bearing apparatus. 
     Referring to  FIG. 12 , the thrust-bearing apparatus  900  and/or radial bearing apparatus  1000  may be incorporated in a subterranean drilling system.  FIG. 12  is a schematic isometric cut-away view of a subterranean drilling system  1100  that includes at least one of the thrust-bearing apparatuses  900  shown in  FIG. 10  according to another embodiment. The subterranean drilling system  1100  includes a housing  1102  enclosing a downhole drilling motor  1104  (i.e., a motor, turbine, or any other device capable of rotating an output shaft) that is operably connected to an output shaft  1106 . A first thrust-bearing apparatus  900   a  ( FIG. 10 ) is operably coupled to the downhole drilling motor  1104 . A second thrust-bearing apparatus  900   b  ( FIG. 10 ) is operably coupled to the output shaft  1106 . A rotary drill bit  1108  configured to engage a subterranean formation and drill a borehole is connected to the output shaft  1106 . The rotary drill bit  1108  is shown as a roller cone bit including a plurality of roller cones  1110 . 
     However, other embodiments may employ different types of rotary drill bits, such as a so-called “fixed cutter” drill bit shown in  FIGS. 8-9 . As the borehole is drilled, pipe sections may be connected to the subterranean drilling system  1100  to form a drill string capable of progressively drilling the borehole to a greater depth within the earth. 
     A first one of the thrust-bearing assemblies  902  of the thrust-bearing apparatus  900   a  is configured as a stator that does not rotate and a second one of the thrust-bearing assemblies  902  of the thrust-bearing apparatus  900   a  is configured as a rotor that is attached to the output shaft  1106  and rotates with the output shaft  1106 . The on-bottom thrust generated when the drill bit  1108  engages the bottom of the borehole may be carried, at least in part, by the first thrust-bearing apparatus  900   a . A first one of the thrust-bearing assemblies  902  of the second thrust-bearing apparatus  900   b  is configured as a stator that does not rotate and a second one of the thrust-bearing assemblies  902  of the thrust-bearing apparatus  900   b  is configured as a rotor that is attached to the output shaft  1106  and rotates with the output shaft  1106 . Fluid flow through the power section of the downhole drilling motor  1104  may cause what is commonly referred to as “off-bottom thrust,” which may be carried, at least in part, by the second thrust-bearing apparatus  900   b.    
     In operation, drilling fluid may be circulated through the downhole drilling motor  1104  to generate torque and effect rotation of the output shaft  1106  and the rotary drill bit  1108  attached thereto so that a borehole may be drilled. A portion of the drilling fluid may also be used to lubricate opposing bearing surfaces of the bearing elements  906  of the thrust-bearing assemblies  902 . 
     Thus, PDCs including one or more partitioning cuts as disclosed herein may be used in any apparatus or structure in which at least one PDC is typically used. In an embodiment, a rotor and a stator, assembled to form a thrust-bearing apparatus, may each include one or more PDCs (e.g., the PDC of  FIG. 3 ) configured 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; 5,480,233; 7,552,782; and 7,559,695, the disclosure of each of which is incorporated herein, in its entirety, by this reference, disclose subterranean drilling systems within which bearing apparatuses utilizing superabrasive compacts disclosed herein may be incorporated. The embodiments of PDCs 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 PDCs disclosed 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; 5,460,233; 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”).