Patent Publication Number: US-10309157-B2

Title: Cutting element incorporating a cutting body and sleeve and an earth-boring tool including the cutting element

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/308,478, filed Jun. 18, 2014, now U.S. Pat. No. 9,816,324, issued Nov. 14, 2017, which is a continuation of U.S. patent application Ser. No. 12/832,817, filed Jul. 8, 2010, now U.S. Pat. No. 8,757,299, issued Jun. 24, 2014, which claims benefit of U.S. Provisional Patent Application No. 61/223,747, filed Jul. 8, 2009, titled “Cutting Element and Method of Forming Thereof,” the disclosure of each of which is hereby incorporated herein in its entirety by this reference. The subject matter of this application is related to U.S. patent application Ser. No. 12/832,823, filed Jul. 8, 2010, now U.S. Pat. No. 8,978,788, issued Mar. 17, 2015, which application claims benefit of U.S. Provisional Patent Application Ser. No. 61/223,748, filed Jul. 8, 2009, titled “Cutting Element for a Drill Bit used in Drilling Subterranean Formations.” The subject matter of this application is also related to U.S. patent application Ser. No. 12/890,415, filed Sep. 24, 2010, which application claims benefit of U.S. Provisional Patent Application No. 61/245,844, filed Sep. 25, 2009, titled “Cutting Element and Method of Forming Thereof.” 
    
    
     TECHNICAL FIELD 
     The following disclosure is directed to cutting elements for use in drill bits and/or milling bits, and particularly cutting elements incorporating a cutting body and a sleeve. 
     BACKGROUND 
     In the past, rotary drill bits have incorporated cutting elements employing superabrasive materials. Within the industry there has been widespread use of synthetic diamond cutters using polycrystalline diamond compacts, otherwise termed “PDC” cutters. Such PDC cutters may be self supported, otherwise a monolithic object made of the desired material, or incorporate a polycrystalline diamond layer or “table” on a substrate made of a hard metal material suitable for supporting the diamond layer. 
     However, PDC cutter designs continue to face obstacles. For example, mechanical strains are commonplace given the significant loading on the cutters, and as such, delamination and fracture of the cutters, particularly of the diamond table, can occur given the extreme loading and temperatures generated during drilling operations. Furthermore, failure of the cutters due to temperature concerns can go beyond the existence of simply encountering high temperatures. In addition, the effects of heating and cooling on the cutters and the resultant failure of the cutters is also due to differences in thermal expansion coefficient and thermal conductivity of materials within the cutter. 
     Various different configurations of cutters have been used to mitigate the effects of mechanical strain and temperature-induced wear characteristics. However, significant shortcomings are still exhibited by conventional cutters. 
     SUMMARY 
     According to one aspect, a cutting element for use in a drilling bit and/or milling bit includes a cutter body comprising a substrate having an upper surface, and a superabrasive layer overlying the upper surface of the substrate. The cutting element further includes a sleeve extending around a portion of a side surface of the superabrasive layer and a side surface of the substrate, wherein the sleeve exerts a radially compressive force on the superabrasive layer. 
     In another aspect, a cutting element for use in a drilling bit and/or milling bit includes a cutter body having a substrate including an upper surface and a superabrasive layer overlying the upper surface of the substrate. The cutting element further includes a sleeve extending around a portion of a side surface of the superabrasive layer and a side surface of the substrate, wherein the sleeve has a coefficient of thermal expansion (CTE) that is different than a coefficient of thermal expansion (CTE) of the superabrasive layer. 
     In still another aspect, a cutting element for use in a drilling bit and/or milling bit includes a cutter body having a substrate including an upper surface and a superabrasive layer overlying the upper surface of the substrate. The cutting element further includes a sleeve in direct contact with and extending around a portion of a side surface of the superabrasive layer and a side surface of the substrate, wherein the sleeve comprises a modulus of elasticity (MOE) that is different than a MOE of the superabrasive layer. 
     According to another aspect, a cutting element for use in a drilling bit and/or milling bit includes a cutter body having a substrate including an upper surface and a superabrasive layer overlying the upper surface of the substrate, wherein the superabrasive layer comprises an upper surface, a rear surface, and a side surface extending between the upper surface and the rear surface. Additionally, the cutting element includes a sleeve in direct contact with and extending around a portion of the side surface of the superabrasive layer. 
     Another aspect of the present application includes a method of forming a cutting element for use in a drilling bit and/or a milling bit comprising forming a cutter body including a substrate and a superabrasive layer overlying a surface of the substrate, forming a sleeve comprising a central opening, and fitting the cutter body within the central opening of the sleeve, wherein the sleeve exerts a radially compressive force on the cutter body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure may be better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. 
         FIG. 1  includes an illustration of a subterranean drilling operation. 
         FIG. 2  includes an illustration of a drill bit in accordance with an embodiment. 
         FIGS. 3A and 3B  include cross-sectional illustrations and a perspective view illustration of a cutter element in accordance with an embodiment. 
         FIG. 4  includes a cross-sectional illustration of a cutter element in accordance with an embodiment. 
         FIGS. 5A-5G  include cross-sectional illustrations of cutter elements in accordance with an embodiment. 
         FIG. 6  includes a cross-sectional illustration of a cutter element in accordance with an embodiment. 
         FIGS. 7A-7D  include cross-sectional illustrations of cutter elements in accordance with embodiments. 
         FIGS. 8A-8D  include cross-sectional illustrations and a side view illustration of cutter elements in accordance with embodiments. 
         FIGS. 9A and 9B  include a cross-sectional illustration and a perspective view illustration of a cutter element in accordance with an embodiment. 
         FIG. 10  includes a cross-sectional illustration of a cutter element in accordance with an embodiment. 
     
    
    
     The use of the same reference symbols in different drawings indicates similar or identical items. 
     DETAILED DESCRIPTION 
     The following is directed to earth boring drilling bits and/or milling bits, and more particularly, cutting elements used in such bits. The following describes cutting elements and methods of forming such elements such that they may be incorporated within drilling and/or milling bits. The terms “bit,” “drill bit,” and “matrix drill bit,” may be used in this application to refer to “rotary drag bits,” “drag bits,” “fixed-cutter drill bits,” “mill-and-drill bits,” “milling bits,” or any bits incorporating the teachings of the present disclosure. As will be appreciated, such drill bits may be used to form well bores or boreholes in subterranean formations as well as mill through casings or other objects within a borehole. 
     An example of a drilling system for drilling such well bores in earth formations is illustrated in  FIG. 1 . In particular,  FIG. 1  illustrates a drilling system including a drilling rig  101  at the surface, serving as a station for workers to operate a drill string  103 . The drill string  103  defines a well bore  105  extending into the earth and can include a series of drill pipes  100  that are coupled together via joints  104 , facilitating extension of the drill string  103  for depths into the well bore  105 . The drill string  103  may include additional components, such as tool joints, a kelly, kelly cocks, a kelly saver sub, blowout preventers, safety valves, and other components known in the art. 
     Moreover, the drill string  103  can be coupled to a bottom-hole assembly (BHA)  107  including a drill bit  109  used to penetrate earth formations and extend the depth of the well bore  105 . The BHA  107  may further include one or more drill collars, stabilizers, a downhole motor, MWD tools, LWD tools, jars, accelerators, push and pull directional drilling tools, point stab tools, shock absorbers, bent subs, pup joints, reamers, valves, and other components. A fluid reservoir  111  is also present at the surface that holds an amount of liquid that can be delivered to the drill string  103 , and particularly the drill bit  109 , via pipes  113 , to facilitate the drilling procedure. 
       FIG. 2  includes a perspective view of a fixed-cutter drill bit according to an embodiment. The fixed-cutter drill bit  200  has a bit body  213  that can be connected to a shank portion  214  via a weld. The shank portion  214  includes a threaded portion  215  for connection of the drill bit  200  to other components of the BHA  107 , as shown in  FIG. 1 . The drill bit body  213  can further include a breaker slot  221  extending laterally along the circumference of the drill bit body  213  to aid coupling and decoupling of the drill bit  200  to other components. 
     The drill bit  200  includes a crown portion  222  coupled to the drill bit body  213 . As will be appreciated, the crown portion  222  can be integrally formed with the drill bit body  213  such that they are a single, monolithic piece. The crown portion  222  can include gage pads  224  situated along the sides of protrusions or blades  217  that extend radially from the crown portion  222 . Each of the blades  217  extend from the crown portion  222  and include a plurality of cutting elements  219  bonded to the blades  217  for cutting, scraping, and shearing through earth formations when the drill bit  200  is rotated during drilling. The cutting elements  219  may be polycrystalline diamond compacts (PDCs) or any of the cutting elements described herein. Coatings or hardfacings may be applied to other portions of the bit body  213  or crown portion  222  to reduce wear and increase the life of the drill bit  200 . 
     The crown portion  222  can further include junk slots  227  or channels formed between the blades  217  that facilitate fluid flow and removal of cuttings and debris from the well bore. Notably, the junk slots  227  can further include openings  223  for passages extending through the interior of the crown portion  222  and bit body  213  for communication of drilling fluid through the drill bit  200 . The openings  223  can be positioned at exterior surfaces of the crown portion  222  at various angles for dynamic fluid flow conditions and effective removal of debris from the cutting region during drilling. 
       FIGS. 3A and 3B  include a cross-sectional illustration and a perspective view illustration of a cutting element in accordance with an embodiment. In particular,  FIG. 3A  includes a cross-sectional illustration of a cutting element employing a cutter body  350  and a sleeve  303  extending around a portion of the cutter body  350  in accordance with an embodiment. The cutter body  350  can include a substrate  301  having an upper surface  307  extending transversely to the longitudinal axis  308 , a rear surface  396  parallel to the upper surface  307  and extending transversely to the longitudinal axis  308 , and a side surface  305  extending between the upper surface  307  and rear surface  396  and extending parallel to the longitudinal axis  308 . The substrate  301  provides a support object for forming a superabrasive layer  302  thereon. 
     In reference to the substrate  301 , the substrate  301  can be made of a material suitable for withstanding drilling applications. For example, the substrate  301  can employ a material having a Mohs hardness of at least about 8, or at least about 8.5, at least about 9.0, or even at least about 9.5. The substrate  301  can be formed of carbides, nitrides, oxides, borides, carbon-based materials, and a combination thereof. Particular metals or metal alloy materials may be incorporated in the substrate  301 , such that the substrate  301  can be made of a cermet. In some instances, the substrate  301  can be made of a cemented material, such as a cemented carbide. Some suitable cemented carbides can include metal carbides, and particularly cemented tungsten carbide. According to one embodiment, the substrate  301  consists essentially of tungsten carbide. 
     The substrate  301  can have a shape comprising an elongated portion defining a length extending along a longitudinal axis  308 . In certain designs, the side surface  305  of the substrate  301  can have an arcuate shape defining a circumference extending at a radius around the longitudinal axis  308 . For instance, the substrate  301  may have a cylindrical shape, such that it has a circular cross-sectional contour as viewed in cross-section to the longitudinal axis  308 . It will be appreciated that alternative shapes for the substrate  301  and cutting elements herein are possible, including polygonal cross-sectional contours (e.g., rectangular, trapezoidal, pentagonal, triangular, etc.), elliptical cross-sectional contours, hemispherical cross-sectional contours, and the like. Accordingly, it will be further appreciated that reference herein to a circumference with regard to a cutting element or any of its components is reference to a dimension extending around the periphery of the identified article in instances where the cutter has a cross-sectional contour other than that of a circle. 
     The cutter body  350  can include a superabrasive layer  302  overlying the upper surface  307  of the substrate  301 . In particular, the superabrasive layer  302  can be in direct contact with (i.e., abutting) the upper surface  307 , and more particularly, bonded directly to the upper surface  307  of the substrate  301 . In certain designs, the superabrasive layer  302  can be formed such that it has a rear surface  316  forming an interface with the upper surface  307  of the substrate  301  extending transversely to the longitudinal axis  308 . The superabrasive layer  302  can have an upper surface  309  parallel to the rear surface  316  and extending transversely to the longitudinal axis  308 . A side surface  306  of the substrate  301  can extend between the rear surface  316  and upper surface  309  parallel to the longitudinal axis  308  of the cutter body  350 . 
     The superabrasive layer  302  can include superabrasive materials such as diamond, boron nitride (e.g., cubic boron nitride), certain carbon-based materials, and a combination thereof. Some superabrasive layers may be in the form of polycrystalline materials. For instance, the superabrasive layer  302  can consist essentially of polycrystalline diamond. With reference to those embodiments using polycrystalline diamond, the superabrasive layer  302  can be made of various types of diamond including thermally stable polycrystalline diamond, which generally contain a lesser amount of catalyst materials (e.g., cobalt) than other diamond materials, making the material stable at higher temperatures. In other applications, the superabrasive layer  302  can be formed such that it consists essentially of polycrystalline cubic boron nitride. 
     In some embodiments, the superabrasive layer  302  has a thickness  332  (t sal ) measured in a direction substantially parallel to the longitudinal axis  308  of the cutter body  350 . The superabrasive layer  302  can have a volume and average thickness  332  (t sal ) suitable for operating in combination with other components (e.g., a sleeve  303 ) for improved performance. Generally, the superabrasive layer  302  may have a thickness  332  (t sal ) of at least about 0.5 mm, such as at least about 1 mm, at least about 2 mm, at least about 3 mm, or even at least about 4 mm. In certain exemplary designs, the superabrasive layer  302  has a thickness  332  (t sal ) within a range between about 0.5 mm and about 5 mm. 
     As further illustrated in  FIG. 3A , the cutting element  300  can include a sleeve  303  extending around a portion of the side surface  306  of the superabrasive layer  302  and the side surface  305  of the substrate  301 . As illustrated, the sleeve  303  comprises an inner surface  310  extending substantially parallel to the longitudinal axis  308 , and an outer surface  311 , opposite the inner surface  310 , extending substantially parallel to the longitudinal axis  308 . Additionally, the sleeve  303  can have an upper surface  313  and a rear surface  314 , each of which can extend between the inner surface  310  and outer surface  311 , parallel to each other and in a direction substantially perpendicular to the longitudinal axis  308  of the cutter body  350 . 
     The inner surface  310  defines a central opening wherein the cutter body  350  can be disposed. In particular, the sleeve  303  can be formed such that the inner surface  310  is in direct contact with the side surface  306  of the superabrasive layer  302 . In particular designs, the sleeve  303  is formed such that the inner surface  310  is directly bonded to the side surface  306  of the superabrasive layer  302 . Likewise, the sleeve  303  can be formed such that the inner surface  310  is directly contacting the side surface  305  of the substrate  301 . For example, in some designs, the inner surface  310  of the sleeve  303  can be directly bonded to the side surface  305  of the substrate  301 . 
     The sleeve  303  can extend along certain portions of the length (i.e., parallel to the longitudinal axis  308 ) of the cutter body  350 . In particular designs, the sleeve  303  extends along at least 50% of the total thickness  332  (t sal ) of the superabrasive layer  302  between the rear surface  316  and the upper surface  309 . In other embodiments, the sleeve  303  is designed to extend over a greater portion of the thickness  332  (t sal ) of the superabrasive layer  302 , such as at least about 60%, at least about 75%, at least about 80%, and even at least about 90%. According to one particular embodiment, the sleeve  303  is formed to extend along the entire thickness  332  (t sal ) of the superabrasive layer  302 . Notably, in such embodiments, the sleeve  303  can be formed such that the upper surface  313  of the sleeve  303  is coplanar with the upper surface  309  of the superabrasive layer  302 . 
     Generally, the sleeve  303  is formed to extend along the entire length of the inner surface  305  of the substrate  301 . However, it will be appreciated that certain embodiments may utilize a sleeve  303  extending for a fraction of the full length of the substrate  301  along the longitudinal axis  308 . 
     The sleeve  303  can be formed such that it extends peripherally (e.g., circumferentially) along the side surfaces  306  and  305  of the superabrasive layer  302  and substrate  301 , respectively. The amount of peripheral coverage of the sleeve  303  can be measured in degrees of coverage based on a central angle measured perpendicular to the longitudinal axis  308  and centered at the center of the cutter body  350  defined by the longitudinal axis  308 . According to some designs, the sleeve  303  can extend through the entire periphery (i.e., 360° of coverage) of the cutter body  350 . That is, the sleeve  303  is a single, monolithic piece extending around the entire circumference of the side surface  306  of the superabrasive layer  302  and the side surface  305  of the substrate  301 . 
     Alternatively, some cutting elements can incorporate a sleeve  303  formed of discrete sleeve portions, wherein each discrete sleeve portion extends through a fraction of the total peripheral distance of the cutter body  350 . For example, a sleeve portion can extend through not greater than 270°, such as not greater than 180°, such as not greater than 90°, or even not greater than 45° of the total peripheral distance of the cutter body  350 . The discrete sleeve portions can be mechanically attached to each other, such as in an interlocking arrangement, through overlapping lips, grooved connections, and the like. In other designs, the discrete sleeve portions may be bonded to each other, such as through the use of a brazing composition. 
     In accordance with embodiments herein, the cutting element  300  is formed such that the sleeve  303  can exert a radially compressive force on the superabrasive layer  302 . Notably, the sleeve  303  is formed and oriented with respect to the superabrasive layer  302  such that it exerts a radially compressive force at the side surface  306  of the superabrasive layer  302 . Accordingly, the forces exerted by the sleeve  303  on the superabrasive layer  302  are provided in a manner such that a significant portion of the force, or even a majority of the force, or even entirely all of the force applied by the sleeve  303  is a radially compressive force acting in a direction substantially perpendicular to the longitudinal axis  308  of the cutter body  350  at the side surface  306  of the superabrasive layer  302 . 
     The cutting element  300  is formed in a manner such that the sleeve  303  can also exert a radially compressive force on the substrate  301 . The sleeve  303  can be oriented with respect to the substrate  301  such that the sleeve  303  exerts a radially compressive force on the substrate  301  at the side surface  305  of the substrate  301 . In particular, a significant portion of the force applied, or even a majority of the total force applied, and in some cases, entirely all of the force applied by the sleeve  303  on the substrate  301  may be a radially compressive force acting on the side surface  305  of the substrate  301  in a direction substantially perpendicular to the longitudinal axis  308  of the cutter body  350 . 
     Notably, embodiments herein utilize a sleeve  303 , which can have a particular shape such that the compressive forces exerted on the superabrasive layer  302  and the substrate  301  are suitable for performance of the cutting element  300 . In particular, the sleeve  303  can be formed such that it has an average thickness  333  (t s ) as measured in a direction perpendicular to the longitudinal axis  308  between the inner surface  310  and the outer surface  311  of the sleeve  303  that is not greater than about 5 mm. According to other embodiments, the sleeve  303  can have an average thickness  333  (t s ) that is at least about 0.1 mm, such as at least about 0.5 mm, at least about 1 mm, at least about 2 mm, or even at least about 3 mm. Still, certain embodiments utilize a sleeve  303  having an average thickness  333  (t s ) that is not greater than about 5 mm, on the order of not greater than about 4 mm, such that it is not greater than about 3 mm, or even not greater than about 2 mm. More particular, designs may utilize an average sleeve thickness  333  (t s ) within a range between about 0.1 mm and about 5 mm, such as between about 1 mm and about 4 mm, such as between about 1 mm and about 3 mm, or even between about 2 mm and about 3 mm. 
     The sleeve  303  may be formed to have a particular outer diameter  334  (OD s ), which when combined with a particular thickness  333  (t s ) of the sleeve  303  provides suitable compressive forces on the superabrasive layer  302 , such that the sleeve  303  exerts suitable forces on the superabrasive layer  302 . In particular embodiments, the sleeve  303  can be formed to have an outer diameter  334  (OD s ) within a range between 8 mm to about 25 mm. 
     Certain cutting elements utilize a sleeve  303  including a metal or metal alloy materials. The metal or metal alloy materials can include transition metal elements. Examples, of some suitable metal elements for use in the sleeve  303  can include titanium, chromium, nickel, tungsten, cobalt, iron, molybdenum, vanadium, and a combination thereof. In certain embodiments, it may be suitable to form a sleeve  303  comprising a superalloy material, which is a refractory metal or metal alloy having superior hardness, and which typically incorporates metal elements such as tungsten, chromium, cobalt, iron, and nickel. Some such suitable superalloys can include nickel-based materials, cobalt-based materials, chromium-based materials, and/or cobalt-chromium-based materials. 
     Additionally, the sleeve  303  can be made of a material such as a carbide, a nitride, a boride, an oxide, a carbon-based material, and a combination thereof. In accordance with one particular embodiment, the sleeve  303  is a cermet material. Particular examples of suitable cermet materials include tungsten carbide material or cemented tungsten carbide. 
     Still, some cutting elements can be formed such that sleeve  303  is made of the same material as the substrate  301 . That is, in some designs, the sleeve  303  and substrate  301  can be made of exactly the same composition. Still, in other embodiments, the sleeve  303  and the substrate  301  may be formed such that they comprise a different material. For example, the sleeve  303  and the substrate  301  may be carbides, however, the sleeve  303  may be formed of a carbide having a different composition than that of the substrate  301 . That is, the sleeve  303  can be formed such that it contains a different element, such as a different metal species. In still other embodiments, the sleeve  303  can be made from a completely different material having an entirely distinct composition than that of the substrate  301 . 
     Referring to  FIG. 3B , a perspective illustration of the cutting element of  FIG. 3A  is provided with a cut-out portion for an internal view of components of the cutting element.  FIG. 3B  provides a fuller understanding of the orientation of the components of the cutting element  300  with respect to each other, with a cut-out portion for an appreciation of the orientation of the substrate  301  and the superabrasive layer  302 . As illustrated, the sleeve  303  can surround the cutter body  350  including the substrate  301  and the superabrasive layer  302 . As described herein, and as will be appreciated, while  FIG. 3B  illustrates a cutting element  300  having a generally cylindrical shape, other polygonal shapes are contemplated, such as elliptical, triangular, rectangular, trapezoidal, hexagonal, irregular, and the like. 
       FIG. 4  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. The cutting element  400  includes components described herein, particularly including a cutter body  450  comprising a substrate  301  and a superabrasive layer  302  overlying an upper surface  307  of the substrate  301 . The cutting element  400  further includes a sleeve  303  extending over the side surface  306  of the superabrasive layer  302  and the side surface  305  of the substrate  301 . Notably, the upper surface  307  of the substrate  301  is formed to have a contoured region  401 . The contoured region  401  can be formed in the upper surface  307  to aid in reduction of stresses in the superabrasive layer  302 . The contoured region  401  can be formed such that it includes a protrusion  402  extending axially along the longitudinal axis  308  and displaced at a position along the longitudinal axis  308  that is different than other points along the upper surface  307 . It will be appreciated, that the contoured region  401  is illustrated as including a protrusion  402 , but other shapes and contours may be used. For example, a series of protrusions or series of grooves may be utilized, and, moreover, patterned shapes may be utilized on the upper surface  307 , such as an arrangement of protrusions appearing as spokes extending radially along the upper surface  307  of the substrate  301  from the center of the upper surface  307  to the side surface  306  of the substrate  301 . 
       FIGS. 5A-5G  include cross-sectional illustrations of cutting elements according to embodiments. In particular,  FIGS. 5A-5G  include illustrations of embodiments using a sleeve having a variable thickness that can have a changing thickness with a change in position in an axial direction, a change in position in a radial direction, or a combination of such directions. The thickness of the sleeve can be a gradual variation (e.g., a tapered form), an abrupt variation (e.g., a stepped configuration), a series of discrete, abrupt variations, or a combination thereof. The thickness of the sleeve can be varied such that the change in thickness is asymmetric. The asymmetry can be based around the longitudinal axis, a radial axis, or a combination thereof. For example, the inner and outer surfaces of the sleeve can be varied such that the change in thickness is asymmetric with regard to the contours of the inner and outer surfaces. Such designs facilitate securing the sleeve and cutter body together, securing the cutting element to a drill bit body, improved performance of the cutting element, and providing varied, and controlled, forces (e.g., radially compressive forces, axial forces, etc.) exerted by the sleeve on different portions of the cutter body. 
       FIG. 5A  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  500  includes a cutter body  550  employing a substrate  301  having a superabrasive layer  302  overlying the upper surface  307  of the substrate  301 . The cutting element  500  further includes a sleeve  503  overlying a side surface  306  of the superabrasive layer  302  and a side surface  305  of the substrate  301 . Generally, cutting elements of any of the embodiments herein can be formed such that a sleeve can have a thickness as measured between the inner surface  510  and the outer surface  311  that varies. That is, the thickness of the sleeve  503  can vary in an axial direction, a radial direction, or a combination thereof. 
     As illustrated in  FIG. 5A , the sleeve  503  is formed such that its thickness varies axially, changing in thickness at different positions along the longitudinal axis  308  of the cutter body  550 . In particular embodiments, the sleeve  503  can have a tapered shape, such that the thickness of the sleeve  503  within region  504  adjacent to the superabrasive layer  302  has a greater thickness than the thickness of the sleeve  503  within region  505  adjacent to the rear surface  396  of the substrate  301 . The provision of the sleeve  503  having a variable thickness can facilitate a difference in the forces exerted at different locations along the cutter body  550 . For example, in the embodiment of  FIG. 5A , the radially compressive forces exerted by the sleeve  503  on the superabrasive layer  302  may be greater than the radially compressive forces exerted by the sleeve  503  in region  505 . 
       FIG. 5B  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  520  includes a cutter body  550  employing a substrate  301  having a superabrasive layer  302  overlying the upper surface  307  of the substrate  301 . The cutting element  520  includes a sleeve  523  overlying a side surface  306  of the superabrasive layer  302  and a side surface  305  of the substrate  301 . According to the illustrated embodiment, the sleeve  523  has a variable thickness achieved by using a tapered surface for the outer surface  311  that extends in a non-parallel direction to the inner surface  510  of the sleeve  523 . That is, the inner surface  510  can be formed such that it extends parallel to the longitudinal axis  308  of the cutter body  550 , but the outer surface  311  of the sleeve  523  is angled relative to the longitudinal axis  308  of the cutter body  550 . In certain embodiments, as illustrated in  FIG. 5B , the outer surface  311  of the sleeve  523  can be tapered such that the sleeve  523  has a greater thickness within region  524  adjacent the superabrasive layer  302  as compared to the thickness of the sleeve  523  within region  525  adjacent to the rear surface  396  of the substrate  301 . It will be appreciated, that other embodiments can be utilized wherein the thickness of the sleeve  523  varies in a different manner, for example, a sleeve wherein the thickness is greater in the region  525  as compared to the thickness of the sleeve in the region  524 . 
       FIG. 5C  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  530  includes a cutter body  550  employing a substrate  301  having a superabrasive layer  302  overlying the upper surface  307  of the substrate  301 . The cutting element  530  includes a sleeve  533  overlying a side surface  306  of the superabrasive layer  302  and a side surface  305  of the substrate  301 . According to the embodiment of  FIG. 5C , the sleeve  523  has a variable thickness achieved by using a tapered outer surface  311  that extends at an angle to the longitudinal axis  308  of the cutter body  550  and a tapered inner surface  510  that extends at an angle to the longitudinal axis  308  of the cutter body  550 . In the particular embodiment illustrated, the sleeve  533  can have a variable thickness, wherein the sleeve  533  has a greater thickness in region  534  as compared to the thickness of the sleeve  533  in region  535 . It will be appreciated that other embodiments can be utilized wherein the thickness of the sleeve  533  varies in a different manner, for example, a sleeve wherein the thickness is greater in the region  535  as compared to the thickness of the sleeve in the region  534 . 
       FIG. 5D  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  560  includes a cutter body  550  employing a substrate  301  having a superabrasive layer  302  overlying the upper surface  307  of the substrate  301 . The cutting element  560  includes a sleeve  563  overlying a side surface  306  of the superabrasive layer  302  and a side surface  305  of the substrate  301 . According to the embodiment of  FIG. 5D , the sleeve  563  has a variable thickness that changes thickness at different axial positions along the longitudinal axis  308  at discrete intervals. As such, the sleeve  563  comprises an inner surface  510  having a stepped configuration including a plurality of discrete steps, wherein each of the steps comprises a different axial and radial position relative to each other and the sleeve  573  comprises a difference in thickness at each of the discrete steps. The illustrated embodiment of  FIG. 5D  utilizes a sleeve  563  having a greater thickness in region  564  as compared to the thickness of the sleeve  563  in region  565 . 
     The substrate  301  can be formed, either through a direct forming process (such as by casting or molding) or by machining to have a side surface  305  having a complementary contour to the inner surface  510  of the sleeve  563 . That is, the substrate  301  can have a side surface  305  comprising a plurality of steps for complementary engagement with the inner surface  510  of the sleeve  563 . Such a design can facilitate an interlocking relationship between the two components. 
     It will be appreciated that other embodiments can be utilized wherein the thickness of the sleeve  563  varies in a different manner, for example, a sleeve wherein the thickness is greater in the region  565  as compared to the thickness of the sleeve in the region  564 . 
     In particular embodiments, the sleeve  563  can have a first step  566  (as shown in  FIGS. 5D, 5F and 5G ) defining the portion of the sleeve  563  having the greatest thickness. Notably, the first step  566  extends for an axial length beyond the thickness of the superabrasive layer  302 . Such a design facilitates formation of a side surface  306  of the superabrasive layer  302  that does not necessarily have to include a variable thickness. Such a design can facilitate ease of processing and formation of the cutting element. 
     It will be appreciated that while the illustrated embodiments demonstrate a symmetrical, stepped configuration for the inner surface  510  of the sleeve  563 , other contours may be utilized. For example, the inner surface  510  can include steps of different radial height, axial length, and a combination thereof. 
       FIG. 5E  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  570  includes a cutter body  550  employing a substrate  301  having a superabrasive layer  302  overlying the upper surface  307  of the substrate  301 . The cutting element  570  includes a sleeve  573  overlying a side surface  306  of the superabrasive layer  302  and a side surface  305  of the substrate  301 . Notably, the sleeve  573  can comprise an outer surface  311  having a stepped configuration including a plurality of discrete steps, wherein each of the steps comprise a different axial and radial position relative to each other and the sleeve  573  comprises a difference in thickness at each of the discrete steps. The illustrated embodiment of  FIG. 5E  utilizes a sleeve  573  having a greater thickness in region  574  as compared to the thickness of the sleeve  573  in region  575 . In such embodiments, the substrate  301  does not necessarily need to be formed to have a complementary, stepped inner surface. Moreover, the plurality of discrete steps can be suitable for securing the cutting element  570  within the drill bit body. 
       FIG. 5F  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  580  includes a cutter body  550  employing a substrate  301  having a superabrasive layer  302  overlying the upper surface  307  of the substrate  301 . The cutting element  580  includes a sleeve  583  overlying a side surface  306  of the superabrasive layer  302  and a side surface  305  of the substrate  301  that incorporates a combination of a tapered surface and a stepped surface. Notably, the sleeve  583  can include an outer surface  311  having a tapered contour extending axially at an angle to the longitudinal axis  308  of the cutter body  550 . Moreover, the inner surface  510  of the sleeve  583  is formed to include a plurality of discrete steps, wherein each of the steps comprises a different axial and radial position relative to each other and the sleeve  583  comprises a difference in thickness at each of the discrete steps. The illustrated embodiment of  FIG. 5F  utilizes a sleeve  583  having a greater thickness in region  584  as compared to the thickness of the sleeve  583  in region  585 . 
       FIG. 5G  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  590  includes a cutter body  550  employing a substrate  301  having a superabrasive layer  302  overlying the upper surface  307  of the substrate  301 . The cutting element  590  includes a sleeve  593  overlying a side surface  306  of the superabrasive layer  302  and a side surface  305  of the substrate  301  that incorporates a combination of a tapered surface and a stepped surface. In fact, the inner surface  510  of the sleeve  593  comprises a combination of a stepped surface and a tapered surface. As illustrated, the inner surface  510  of the sleeve  593  is formed to include a plurality of discrete steps, wherein each of the steps comprises a different axial and radial position relative to each other and the sleeve  593  comprises a difference in thickness at each of the discrete steps. In fact, the inner surface  510  comprises a first step  566  that extends along the side surface  306  of the superabrasive layer  302  and a portion of the side surface  305  of the substrate  301 . The first step  566  extends generally parallel to the longitudinal axis  308  of the cutter body  550 . The inner surface  510  further comprises another portion including a vertical surface  597  joining the first step  566  with a tapered step surface  596 , which extends axially at an angle to the longitudinal axis  308  toward the rear surface  396  of the substrate  301 . 
     Moreover, the cutting element  590  includes an outer surface  311  of the sleeve  593  that comprises a plurality of discrete steps, wherein each of the steps comprises a different axial and radial position relative to each other and each of the steps defines an abrupt change in the thickness of the sleeve  593 . As illustrated, the sleeve  593  has a greater thickness in region  594  as compared to the thickness of the sleeve  593  in region  595 . As contemplated by embodiments herein, the inner surface  510  and the outer surface  311  of the sleeve  593  can be formed such that the surfaces  510 ,  311  have different contours relative to each other to control the forces exerted by the sleeve  593  on the substrate  301  at different axial and radial positions. 
     Generally, cutting elements of embodiments herein can utilize a sleeve and a cutter body that are mechanically interlocked with each other. In particular instances, the sleeve can be formed such that it can be mechanically interlocked with the substrate. Mechanically interlocking connections between the cutter body and the sleeve can be accomplished by incorporation of interfacial surface features on the inner surface of the cutter body, particularly the substrate, and/or the sleeve. Notably, such interfacial features can include the use of complementary engaging features that are designed to interlock the sleeve and cutter body at the interface between the sleeve and cutter body. Some suitable examples of interfacial surface features can include grooves and/or protrusions extending axially and/or radially along the inner surface of the sleeve and cutter body, honeycomb structures, threaded surfaces, and the like. 
     One such design of mechanically interlocking orientation between the components is provided in  FIG. 6 .  FIG. 6  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  600  includes a cutter body  650  comprising a substrate  301  and a superabrasive layer  302  overlying an upper surface  307  of the substrate  301 . A sleeve  603  extends over the side surface  306  of the superabrasive layer  302  and the side surface  305  of the substrate  301 . 
     According to one embodiment, the sleeve  603  and the substrate can include a contoured region  601  along their respective inner surfaces  310  and  305  for complementary engagement and mechanically interlocking the two components. Contoured region  601  can include protrusions, grooves, lips, or any other surface features suitable for interlocking engagement between the sleeve  603  with the substrate  301 . As illustrated in  FIG. 6 , the sleeve  603  comprises a protrusion  604  extending radially inward along the inner surface  310  that is configured to be engaged with a complementary groove  605  within the side surface  305  of the substrate  301 . As will be appreciated, the protrusion  604  may extend for a portion of the peripheral (e.g. circumferential) dimension of the inner surface  310  of the sleeve  603 . That is, the protrusion  604  may extend peripherally along the inner surface  310  of the sleeve  603  for a distance of at least about 45°, at least about 90°, or even at least about 180°. In certain instances, the protrusion  604  may extend for the full peripheral dimension of the inner surface  310  of the sleeve  603  (i.e., 360°). Likewise, the complementary groove  605  may extend for the same distance for proper complementary engagement of the groove  605  therein. 
       FIGS. 7A-7D  include cross-sectional illustrations of cutting elements in accordance with embodiments.  FIG. 7A  includes a cross-sectional illustration of a cutting element  700  including a cutter body  750  employing a substrate  301  and a superabrasive layer  302  overlying an upper surface  307  of the substrate  301 . Additionally, the cutting element  700  includes a sleeve  703  that extends over the side surface  306  of the superabrasive layer  302  and the side surface  305  of the substrate  301 . Notably, the cutter body  750  is formed such that the superabrasive layer  302  comprises a chamfered surface  706  extending at an angle to the longitudinal axis  308  of the cutter body  750  and located between the upper surface  309  and side surface  306  of the superabrasive layer  302 . 
     The chamfered surface  706  can improve the cutting performance of the cutting element  700 . Various angles and lengths of the chamfered surface  706  may be employed. As will be appreciated, the chamfered surface  706  may extend as an annulus around the entire periphery of the superabrasive layer  302 . However, the chamfered surface  706  may be segmented, such that it is made of discrete portions, wherein each portion extends for a distance less than the entire periphery (i.e., less than 360°). Moreover, in certain instances, it may be desirable to use a radiused edge as opposed to a chamfered surface. A radiused edge can have a curvature or arcuate shape that can be defined by a radius. As such, it will be appreciated that references herein to chamfered surfaces will be understood to also include radiused edge configurations. 
     As further illustrated, the sleeve  703  of the cutting element  700  is oriented such that it overlies the side surface  306  of the superabrasive layer  302 . The sleeve  703  is formed such that it includes an upper surface  705  that extends perpendicular to the longitudinal axis  308  of the cutter body  750 . Notably, the sleeve  703  is placed around the cutter body  750  such that an upper surface  705  of the sleeve  703  abuts and extends from a joint between the chamfered surface  706  and side surface  306  of the superabrasive layer  302 . At least a portion of the sleeve  703  overlies the side surface  306 , and in particular, is abutting the side surface  306  of the superabrasive layer  302 . 
       FIG. 7B  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Notably, cutting element  720  includes some of those components described in the embodiment of  FIG. 7A . In addition to the chamfered surface  706  of the superabrasive layer  302 , the cutting element  720  further includes an arresting layer  721  disposed between the chamfered surface  706  of the superabrasive layer  302  and the inner surface  310  of the sleeve  703 . Notably, the arresting layer  721  can be in direct contact with the chamfered surface  706  and inner surface  310 . Moreover, the arresting layer  721 , in certain designs, can be directly bonded to the chamfered surface  706  and inner surface  310 . 
     The arresting layer  721  can be formed of a material having a Mohs hardness that is less than a Mohs hardness of the superabrasive layer  302 . For example, the arresting layer  721  can be made of a material such as a carbide, a nitride, an oxide, a boride, a carbon-based material, and a combination thereof. Certain suitable types of materials for use in the arresting layer  721  can include ceramics, metals, and cermets. In particular instances, the arresting layer  721  can be formed such that it is made of a carbide. Still, in other designs, the arresting layer  721  can be formed of a metal or metal alloy and may particularly include certain metal elements such as nickel, iron, manganese, chromium, tantalum, vanadium, titanium, cobalt, tungsten, and a combination thereof. For example, one particular type of arresting layer  721  can be made of a steel composition. Notably, in particular embodiments, the arresting layer  721  can be formed of a metal braze composition or a metal binder composition. 
     In still other designs, it may be suitable to incorporate certain superalloy compositions within the arresting layer  721 . Reference to superalloy materials is reference to refractory metal and metal alloys having superior hardness, and which typically incorporate metal elements such as tungsten, chromium, cobalt, iron, and nickel. Some such suitable superalloys can include nickel-based materials, cobalt-based materials, chromium-based material, and/or cobalt-chromium-based materials. In fact, superalloy compositions include a majority amount of nickel, chromium, and/or cobalt (depending upon the precise composition) and may further include minor amounts of other alloying metal elements, such as molybdenum, tungsten, iron, and manganese. Some minor amounts of elements such as silicon and carbon may also be present. Examples of such materials include STELLITE®, INCONEL®, HASTELLOY® and TALONITE™. 
     Moreover, designs herein may incorporate an arresting layer  721  that exerts a radially compressive force on the superabrasive layer  302 . For example, the arresting layer  721  can be formed such that it exerts a force on the superabrasive layer  302 , and a portion of the total force, a majority of the total force, or even essentially all of the total force exerted by the arresting layer  721  can be a radially compressive force applied directly to the chamfered surface  706 . Optionally, in some cutting elements, the arresting layer  721  may be in direct contact with the side surface  306  of the superabrasive layer  302 , such that it is disposed between the side surface  306  and inner surface  310  of the sleeve  703 . In such embodiments, the arresting layer  721  can further exert a radially compressive force on the superabrasive layer  302  at the side surface  306 . 
       FIG. 7C  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  730  includes some of the elements previously described in  FIG. 7A . However, the cutting element  730  comprises a sleeve  703  having a different orientation with respect to the superabrasive layer  302  than the cutting element  700  of  FIG. 7A . In particular, the sleeve  703  is formed with a protrusion  732  that extends radially inward from the inner surface  310 . The protrusion  732  can overly the chamfered surface  706  of the superabrasive layer  302 . In particular embodiments, the protrusion  732  is formed such that it directly contacts, and can be directly bonded to, the chamfered surface  706  of the superabrasive layer  302 . The protrusion  732  incorporates an inner surface  733  that is angled with respect to the longitudinal axis  308  for complementary engagement with the chamfered surface  706  of the superabrasive layer  302 . 
     The provision of the protrusion  732  on the sleeve  703  may facilitate the exertion of forces on the superabrasive layer  302 . In particular, the protrusion  732  can exert a radially compressive force on the superabrasive layer  302 . Additionally, the protrusion  732  can be formed such that it applies an axial force to the superabrasive layer  302 . 
       FIG. 7D  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  740  includes components described herein, particularly including a cutter body  750  comprising a substrate  301  and a superabrasive layer  302  overlying an upper surface  307  of the substrate  301 . The cutting element of  740  further includes a sleeve  703  extending over the side surface  306  of the superabrasive layer  302  and the side surface  305  of the substrate  301 . In particular, the sleeve  703  is formed such that it comprises an upper surface  741  that is angled with respect to the longitudinal axis  308  and extends between the inner surface  310  and outer surface  311  of the sleeve  703 . In accordance with certain designs, the upper surface  741  of the sleeve can be formed such that it is coplanar with the chamfered surface  706  of the superabrasive layer  302 . The cutting element  740  facilitates protrusion of the superabrasive layer  302  in an axial direction beyond the upper surface  741  of the sleeve  703  while maintaining the orientation of the sleeve  703  with respect to the side surface  306  of the superabrasive layer  302  for exertion of forces thereon. 
       FIGS. 8A-8D  include cross-sectional illustrations of cutting elements in accordance with the embodiments. Generally, the embodiments of  FIGS. 8A-8D  include a sleeve that comprises multiple portions, including an upper portion that can overlie at least a portion of the upper surface of the superabrasive layer. In certain instances, the upper portion of the sleeve can overlie a majority, or even an entirety of the upper surface of the superabrasive layer. Accordingly, the sleeve may act as an encapsulating material, which may initiate the cutting in the down-hole environment through rock strata or an existing casing, only to erode and later expose the underlying superabrasive layer. Alternatively, the sleeve can be formed to have an upper portion that selectively overlies portions of the superabrasive layer, while leaving other portions of the superabrasive layer exposed. 
       FIG. 8A  includes a cross-sectional illustration of a cutting element  800  comprising a cutter body  850 , and a sleeve  803  encapsulating a majority of the cutter body  850 . As illustrated, the sleeve  803  is formed such that it has a side portion  801  extending over the side surface  306  of the superabrasive layer  302  and the side surface  305  of the substrate  301 . Moreover, the sleeve  803  further includes an upper portion  814  extending perpendicularly to the longitudinal axis  308  and overlying a portion of the upper surface  309  of the superabrasive layer  302 . The upper portion  814  can be bonded to the side portion  801 . However, particular embodiments utilize a sleeve wherein the side portion  801  and upper portion  814  are part of a single, monolithic object that may not necessarily be separate components bonded together. 
     In accordance with certain designs, the sleeve  803  is formed such that the upper portion  814  overlies at least about 50% of the total surface area of the upper surface  309  of the superabrasive layer  302 . That is, as illustrated, the upper portion  814  can overlie a portion of the upper surface  309  of the superabrasive layer  302  such that a central opening  807  exists in the upper portion  814  where the upper surface  309  of the superabrasive layer  302  is exposed (i.e., uncovered). In certain designs, the exposed portion of the superabrasive layer  302  within the central opening  807  can be centered around the longitudinal axis  308 . The upper portion  814  can overlie a greater amount of the upper surface  309 , such as at least about 75%, at least about 80%, or even at least about 90% of the upper surface  309  of the superabrasive layer  302 . In one particular design, the upper portion  814  overlies an entirety of the upper surface  309  of the superabrasive layer  302 . 
     As illustrated, the upper portion  814  of the sleeve  803  can be in direct contact with the upper surface  309 . In certain instances, the upper portion  814  is formed such that it can be in direct contact with, and even directly bonded to, the upper surface  309  of the superabrasive layer  302 . As such, cutting elements like cutting element  800  illustrated in  FIG. 8A  comprise a sleeve  803  that can exert forces on the superabrasive layer  302 . In particular, the upper portion  814  can exert an axially compressive force, a radially compressive force, or a combination thereof, that is directly applied to the upper surface  309  of the superabrasive layer  302 . 
       FIG. 8B  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. In particular,  FIG. 8B  includes a cutting element  820  having certain components described in the embodiment of  FIG. 8A . Notably, the cutting element  820  is formed such that the cutter body  850  comprises a superabrasive layer  302  having a chamfered surface  806  extending at an angle to the longitudinal axis  308  between the upper surface  309  and side surface  306  of the superabrasive layer  302 . The sleeve  803  comprises a side portion  801  extending over the side surface  305  of the substrate  301  and the side surface  306  of the superabrasive layer  302 . The sleeve  803  further comprises a upper portion  814  extending over the entirety of the upper surface  309  of the superabrasive layer  302 . Notably, the sleeve  803  comprises a radiused edge  817  extending between the outer surface  311  of the side portion  801  of the sleeve  803  and an upper surface  809  of the upper portion  814  of the sleeve  803 . As will be appreciated, the radiused edge can have various curvatures depending upon intended application of the cutter. 
     The cutting element  820  further includes an arresting layer  816  disposed within a gap between the chamfered surface  806  of the superabrasive layer  302  and an inner corner of the sleeve  803  defined by a conjunction of the inner surface  310  of the side portion  801  and an inner surface  810  of the upper portion  814 . The arresting layer  816  can incorporate the same materials, have the same orientation, and exert the same forces on the superabrasive layer  302  as the arresting layer  721  as described in the embodiment of  FIG. 7B . 
       FIG. 8C  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. In particular,  FIG. 8C  includes a cutting element  830  having those components described in the embodiment of  FIG. 8A . Notably, the cutting element  830  is formed such that the cutter body  850  comprises a superabrasive layer  302  having a chamfered surface  825  extending at an angle to the longitudinal axis  308  between the upper surface  309  and side surface  306  of the superabrasive layer  302 . The sleeve  821  can be formed such that it comprises a chamfered surface  823  extending at an angle to the longitudinal axis  308  between the upper surface  809  of the upper portion  814  and a side surface  811  of the side portion  801 . Additionally, the sleeve  821  can include a chamfered surface  827  along its inner surface extending at an angle to the longitudinal axis  308  between the inner surface  310  of the side portion  801  and the inner surface  810  of the upper portion  814 . As such, the chamfered surface  827  can have the same angle and length of the chamfered surface  825  of the superabrasive layer  302  for complementary engagement of the surfaces  825  and  827  and proper orientation between the cutter body  850  and sleeve  821 . Various angles and lengths of the chamfered surfaces  825  and  827  may be employed. 
       FIG. 8D  includes a side view illustration of a cutting element in accordance with an embodiment. In particular,  FIG. 8D  includes a cutting element  840  having certain components described in the embodiment of  FIG. 8A . Notably, the cutting element  840  is formed such that the cutter body  850  comprises a superabrasive layer  302  having a chamfered surface  825  extending at an angle to the longitudinal axis  308  between the upper surface  309  and side surface  306  of the superabrasive layer  302 . Additionally, as illustrated in the embodiment, the sleeve  841  can be formed such that it comprises a surface  843 , which can extend in an arcuate manner to the side surface  811  of the side portion  801  and upper surface  809  of the upper portion  814  of the sleeve  841 . The surface  843  facilitates formation of an opening  845 , wherein a portion of the superabrasive layer  302  is exposed (i.e., not underlying the sleeve  841 ), and particularly, the chamfered surface  825  as shown by dashed line, of the superabrasive layer  302  is exposed. The opening  845  within the sleeve  841  can be shaped to have any contour to effectively expose a portion of the superabrasive layer  302 . As illustrated, the surface  843  may comprise a curved contour to increase the exposure of the superabrasive layer  302 , however, in other embodiments, it may include simply a straight, chamfered surface. 
     As illustrated, the upper portion  814  of the sleeve  841  can be in direct contact with the upper surface  309  of the superabrasive layer  302 . In certain instances, the upper portion  814  is formed such that it can be in direct contact with, and even directly bonded to, the upper surface  309  of the superabrasive layer  302 . As such, cutting elements like cutting element  840  illustrated in  FIG. 8D  comprise a sleeve  841  that can exert forces on the superabrasive layer  302 . In particular, the upper portion  814  can exert an axially compressive force, a radially compressive force, or a combination thereof, that is directly applied to the upper surface  309  of the superabrasive layer  302 . Moreover, the design of the sleeve  841  is such that it can directly overlie the center point of the upper surface  309  of the superabrasive layer  302 , such that even during use, the sleeve  841  can maintain its position and continue to exert forces on the superabrasive layer  302 . 
     With regard to the embodiments of  FIG. 8A-8D , it will be appreciated that such cutters can be employed in rotary drag bits. Moreover, such cutting elements may be particularly suitable for use in mill-and-drill bits, which are designed to mill through obstructions (e.g., casings) contained within a borehole before continuing a drilling process configured to subsequently engage subterranean (i.e., rock). As such, the provision of the sleeve overlying the upper surface of the superabrasive layer facilitates protection of the superabrasive layer  302  while the bit is milling through an obstruction, saving the superabrasive layer  302  for engagement with subterranean formations for efficient drilling operations. 
       FIGS. 9A and 9B  include a cross-sectional illustration and a perspective view illustration of a cutting element in accordance with an embodiment.  FIG. 9A  includes a cross-sectional illustration of a cutting element  900  having a cutter body  950  comprising a substrate  301  and a superabrasive layer  302  overlying an upper surface  307  of the substrate  301 . The cutting element  900  further includes a sleeve  901  overlying the side surface  306  of the superabrasive layer  302  and the side surface  305  of the substrate  301 . The sleeve  901  is formed such that it has a thickness that varies radially. That is, the thickness of the sleeve  901  changes at different radial position along the sleeve  901 . As illustrated, the sleeve  901  has a thickness within region  903  that is significantly greater than the thickness of the sleeve  901  within region  902 . 
     Additionally, according to certain embodiments, the cutting element  900  can be formed such that the cutter body  950  and the sleeve  901  are oriented in a non-concentric relationship to one another.  FIG. 9B  includes a perspective view illustration of the cutting element  900  for a fuller understanding of the orientation between the components. As shown, the cutter body  950  can be disposed within the opening of the sleeve  901  such that the longitudinal axis  308  of the cutter body  950 , which extends through a center point of the cutter body  950 , is spaced apart from and extends along a different axis than a longitudinal axis  908  extending through a center point of the sleeve  901 . Such a configuration may facilitate the orientation of the cutting element  900  within a bit, such that the thinner portion of the sleeve  901  within region  902  is configured to initiate cutting, while the thicker portion of the sleeve  901  within the region  903  is configured to maintain the cutter body  950  within the sleeve  901 . 
       FIG. 10  includes a cross-sectional illustration of a cutting element in accordance with an embodiment. Cutting element  1000  includes a cutter body  1050  comprising a substrate  301  and a superabrasive layer  302  overlying an upper surface  307  of the substrate  301 . The cutting element  1000  further includes a sleeve  303  overlying a portion of the side surface  306  of the superabrasive layer  302  and a portion of the side surface  305  of the substrate  301 . The cutting element  1000  includes an intermediate layer  1001  disposed between the upper surface  307  of the substrate  301  and the rear surface  316  of the superabrasive layer  302 . In particular embodiments, the intermediate layer  1001  comprises a rear surface  1002  that is in direct contact with, and can be directly bonded to, the upper surface  307  of the substrate  301 . Moreover, the intermediate layer  1001  can have an upper surface  1003  in direct contact with, and can be directly bonded to, the rear surface  316  of the superabrasive layer  302 . 
     The intermediate layer  1001  can be made of a material such as a carbide, carbon-based material, and a combination thereof In particular instances, the intermediate layer  1001  can be made of a carbide, such as a metal carbide like titanium carbide or tungsten carbide. Still, in other instances, the intermediate layer  1001  can be formed of a diamond material, such as a polycrystalline diamond material. In yet other designs, a cermet material may be utilized within the intermediate layer  1001 . 
     While the intermediate layer  1001  can be made of a different material than the superabrasive layer  302  or the substrate  301 , in certain designs, the intermediate layer  1001  can include the same materials as the superabrasive layer  302  or the substrate  301  and yet have different material characteristics than the superabrasive layer  302 . This can be achieved by using different feed material (or a grade of material) in forming the different components (i.e., substrate  301 , intermediate layer  1001 , and superabrasive layer  302 ). For example, in one embodiment, the superabrasive layer  302  and the intermediate layer  1001  can include a diamond material (e.g., PDC or TSP), wherein the superabrasive layer  302  is formed from a different diamond feed material than the intermediate layer  1001 . The feed material can be varied to control performance characteristics of the as-formed layer. For example, the feed material used to form the layers can be distinguished based upon the size of the grains, the size distribution of the grains, and the quality of the grains (compositional purity, etc.), which can affect toughness, abrasiveness, and other mechanical characteristics. That is, in certain embodiments, a feed material can be used to form the superabrasive layer  302  such that it has greater abrasiveness as compared to the feed material used to form the intermediate layer  1001 , which may be formed to have a greater toughness as compared to the superabrasive layer  302 . 
     The intermediate layer  1001  can be formed to have an upper surface  1003  having a contoured region like the upper surface  307  of the substrate  301  in  FIG. 4 . While not illustrated, it will be appreciated, that the substrate  301  can also include a contoured region in the upper surface  307 . Such a design may improve bonding between the substrate  301  and the superabrasive layer  302  and also reduce stresses within the superabrasive layer  302 . As will be appreciated, other contours within the upper surface  1003  of the intermediate layer  1001  may be utilized including, for example, a series of protrusions and/or a series of grooves, which may further form a pattern, such as an arrangement of protrusions appearing as spokes extending radially along the upper surface  1003 . 
     Notably, the intermediate layer  1001  is formed such that it can exert forces on the superabrasive layer  302 . For instance, the intermediate layer  1001  can be formed to exert some radially compressive forces on the superabrasive layer  302  at the interface between the upper surface  1003  and rear surface  316  of the superabrasive layer  302 . 
     Additionally, while not illustrated, the intermediate layer  1001  can comprise a plurality of discrete films, wherein each of the films comprises a different characteristic relative to an abutting film. Use of a plurality of discrete films within the intermediate layer  1001  may improve bonding between the substrate  301 , intermediate layer  1001 , and superabrasive layer  302 . Moreover, the use of an intermediate layer  1001  comprising a plurality of discrete films may include the formation of a graded structure. That is, an intermediate layer having a composition that changes through the formation of a discrete films having different grades. Films of different grade can include films that differ based upon the material composition of the materials between two films or that have a difference in microstructure (e.g., size of grains, shape of grains, distribution of sizes and shapes of grains, etc.) 
     The cutting elements herein may be formed by particular methods such that the components are properly oriented with respect to each other and forces between components are applied as described herein. In accordance with an embodiment, one method of forming includes forming the cutter body comprising the substrate and superabrasive layer as illustrated in embodiments herein. One particular method of forming the cutter body can include a high-pressure/high-temperature (HP/HT) process. 
     In an HP/HT process, substrate material is loaded into an HP/HT cell with an appropriate orientation and amount of diamond crystal material, typically of a size of 100 microns or less. Furthermore, a metal catalyst powder can be added to the HP/HT cell, which can be provided in the substrate or intermixed with the diamond crystal material. The loaded HP/HT cell is then placed in a process chamber, and subjected to high temperatures (typically 1450° C. to 1600° C.) and high pressures (typically 50 to 70 kilobar), wherein the diamond crystals, stimulated by the catalytic effect of the metal catalyst powder, bond to each other and to the substrate material to form a PDC product. It will be appreciated that the PDC product can be further processed to form a thermally stable polycrystalline diamond material (commonly referred to as a “TSP”) by leaching out the metal in the diamond layer. Alternatively, silicon, which possesses a coefficient of thermal expansion similar to that of diamond, may be used to bond diamond particles to produce an Si-bonded TSP. TSPs are capable of enduring higher temperatures (on the order of 1200° C.) in comparison to normal PDCs. 
     The process of forming the cutting elements herein may further include a process of forming a sleeve having the dimensions described herein and particularly a central opening for engagement of the cutter body therein. Various forming methods may be undertaken to form the sleeve. For example, an HP/HT process may be used to form the sleeve. In particular instances, the cutter body and sleeve may be formed in the same high-pressure/high-temperature process. In certain instances, the formation of the cutter body and the sleeve can be completed simultaneously, such that they are formed in the same chamber at the same time. Such a process may require a special HP/HT cell capable of accommodating both components. 
     In accordance with other embodiments, depending upon the material of the sleeve selected, the sleeve may be formed through a different method. For example, some suitable methods of forming the sleeve can include machining, casting, molding, pressing, forging, sintering, and a combination thereof. 
     After forming the cutter body and sleeve, the cutter body and sleeve may be fitted together such that the cutter body is placed within the central opening of the sleeve in a manner such that the sleeve exerts radially compressive forces on the cutter body, and particularly the superabrasive layer. In accordance with one embodiment, the process of fitting the cutter body and sleeve together includes a process of creating a temperature differential between the cutter body and sleeve. The process of creating a temperature differential may include increasing the temperature of the sleeve, such as by heating the sleeve to a temperature greater than a temperature of the cutter body. Such a process may facilitate an increase in the dimensions of the sleeve, such that the diameter of the central opening is increased sufficiently for fitting of the cutter body within the sleeve. As such, the dimensions of the sleeve may initially be created such that the cutter body may not necessarily fit within the central opening of the sleeve. However, after providing a temperature differential between the two components, the cutter body and sleeve can be combined such that the cutter body fits within the opening of the sleeve. 
     Alternatively, the process of creating a temperature differential between the cutter body and sleeve can include a process of decreasing the temperature of the cutter body relative to the temperature of the sleeve. Such a process may facilitate reduction in the dimensions of the cutter body such that the cutter body fits within the central opening of the sleeve. It will be appreciated that the process of creating the temperature differential can include one or a combination of the techniques. That is, the temperature of the sleeve can be changed relative to the cutter body, the temperature of the cutter body can be changed relative to the sleeve, or the temperature of both components may be changed relative to each other to complete the fitting process. 
     In accordance with one particular embodiment, the temperature differential is at least about a 10% difference in temperature between the two components based on the greater of the two temperatures. For example, the percentage difference in temperature differential can be calculated based on the equation: ((T1−T2)/T1)×100, wherein T1&gt;T2. Other processes may utilize a greater temperature differential, such as on the order of at least about 25% difference, at least about 50% difference, at least about 75% difference, or even at least about a 90% difference in temperature between the components. Still, creation of the temperature differential may be controlled to lessen the likelihood of temperature induced damages to the components, and accordingly, the temperature differential may be within a range between about 10% and about 90%, between about 10% and about 75%, or even between an about 10% and 50% difference in temperature between the two components. 
     Upon creating a sufficient temperature differential, the cutter body can be disposed within the central opening of the sleeve, and the components can be fitted together and properly oriented with respect to each other. It has been revealed that a sufficient clearance or gap distance must be utilized, by virtue of the temperature differential, between the inner diameter of the sleeve and the outer diameter of the cutter body to affect proper fitting of the two components. According to studies conducted, it has been found that a clearance of at least about 0.005 cm between the two components is suitable for proper fitting. Additionally, some processes may utilize a greater clearance, such as at least about 0.0075 cm, at least about 0.01 cm, at least about 0.02 cm, or even greater. Particular temperature differentials according to processes herein can facilitate the creation of a clearance of between about 0.005 cm and about 0.02 cm. 
     After properly fitting the two components together the temperature differential between the components can be removed. Reduction or removal of the temperature differential can include cooling of the components together, heating of the components together, or a combination thereof. As such, upon removal of the temperature differential between the two components, the diameter of the central opening of the sleeve with respect to the cutter body is such that a radially compressive force is exerted by the sleeve on the side surfaces of the cutter body. 
     It will further be appreciated that in some processes, a bonding material may be placed at the interface between the sleeve and the cutter body to facilitate joining the two components. Suitable bonding materials may be inorganic or organic materials. For example, the bonding material can be a braze material incorporating a metal or a metal alloy material. Metal materials of particular use may include metal elements including, for example, nickel, iron, manganese, chromium, tantalum, vanadium, titanium, cobalt, tungsten, and a combination thereof. Notably, superalloy metals as described herein can also be employed. 
     While particular reference to the process of fitting the components together has focused on the use of a temperature differential, other processes may be used. For example, it is contemplated that a mechanical force may be applied to the sleeve, cutter body, or both, to affect the fitting of the cutter body within the central opening of the sleeve. In one particular instance, a force can be applied to the sleeve to increase the inner diameter of the central opening to allow the cutter body to fit within the sleeve. As such, in particular instances, the cutter body may be extruded into the sleeve, such that a mechanical urging force is applied to the substrate to urge the cutter body into the central opening of the sleeve, and thereby creating a cutting element wherein the sleeve exerts forces (e.g., radial and axial forces) on the cutter body. 
     In other processes, a press fitting operation can be used to fit the components (i.e., the sleeve and the cutter body) together. Press fitting operations can utilize the application of force on the cutter body and/or sleeve to affect fitting of the sleeve and cutter body together in a manner such that the sleeve exerts at least a radially compressive force on the cutter body. In particular instances, the press fitting operation can include the formation of a sleeve having a central opening designed to allow the cutter body to fit within the central opening. This may be accomplished with or without the application of a temperature differential or other forces to the sleeve. During the press fitting operation, the cutter body can be forced into the central opening of the sleeve, such that the sleeve is forced to expand, and, consequently, the sleeve also applies opposite forces to the cutter body. In particular instances, it may be particularly suitable to introduce the cutter body into the sleeve such that the superabrasive layer is first introduced into the central opening. The cutter body is axially displaced through force within the central opening until the proper fit is obtained and the cutter body is properly seated within the sleeve. It will be appreciated that chamfered surfaces on the rear of the sleeve or on the superabrasive layer or both may aid the initiation of the fitting operation. 
     After fitting the cutter body within the central opening of the sleeve, a radially compressive force can be applied to the sleeve and cutter body to physically reduce the size of the sleeve and compress the sleeve. Compression of the sleeve can facilitate the creation of a frictional bond between the two components and the exertion of a radially compressive force on the cutter body by the sleeve. It will be appreciated that certain mechanical features at the interface of the sleeve and cutter body, particularly the substrate, may be utilized to facilitate locking engagement and maintaining the compressive state of the sleeve. 
     Embodiments herein may utilize a particular difference in materials used to form the components such as the sleeve, superabrasive layer, and substrate. Notably, the sleeve may be formed of a material having a coefficient of thermal expansion (CTE) that is different than the coefficient of thermal expansion of the material of the superabrasive layer. In accordance with embodiments herein, the sleeve and the superabrasive layer can comprise CTEs that are at least about 5% different as measured at 300 K based on the greater CTE. For example, the percentage difference in CTE can be calculated based on the equation: ((CTE 1 −CTE 2 )/CTE 1 )×100, wherein CTE 1 ≥CTE 2 . In other designs, the difference may be greater, such as at least about 10%, at least about 15%, at least about 20%, or even at least 25% difference in CTE between the sleeve and superabrasive layer at 300 K. Still, particular embodiments may utilize a difference in CTE between the sleeve and superabrasive layer as measured at 300 K within a range between about 5% and 90%, such as between 5% and 75%, between about 5% and about 50%, or even between about 5% and 25%. In such embodiments, it may be particularly suitable that the CTE of the sleeve material is greater than the CTE of the superabrasive layer. 
     The description herein has indicated that certain embodiments may utilize a CTE difference between certain components, such as the sleeve, cutter body, and particularly the superabrasive layer. However, it has been revealed that in certain embodiments, a cutting element can be formed wherein a radially compressive force is applied by the sleeve on the superabrasive layer, wherein the relationship between the CTE of the sleeve (CTE s ) and the CTE of the superabrasive layer (CTE sal ) is as follows: ((CTE s −CTE sal )/CTE s )×100, wherein CTE s ≥CTE sal . Notably, in such designs, the CTE of the sleeve can be equal to the CTE of the superabrasive layer. More particularly, the CTE of the sleeve can be greater than the CTE of the superabrasive layer. In such embodiments, the percentage difference in CTE between the sleeve and the superabrasive layer are the same as the percentage differences described in accordance with embodiments herein. 
     In other terms, the embodiments herein can employ a sleeve having a CTE that is at least about one order of magnitude greater than the CTE of the superabrasive layer  302  as measured at 300 K. That is, the difference in CTE between the sleeve and the superabrasive layer is at least a multiple of ten. In more particular instances, the sleeve can have a CTE that is at least two orders of magnitude greater than the CTE of the sleeve, or even on the order of at least three orders of magnitude greater. Certain designs according to embodiments herein can utilize a sleeve having a CTE that is between about one order of magnitude and about four orders of magnitude greater than the CTE of the superabrasive layer. 
     While particular reference above is made to the difference in CTE between the sleeve and the superabrasive layer, it will be appreciated that such differences in CTE may also be employed between other components, particularly between the sleeve and the substrate, the intermediate layer and the substrate, and/or the intermediate layer and the superabrasive layer. Moreover, such differences in CTE may be utilized between discrete films within the intermediate layer. 
     Additionally, cutting elements of embodiments herein may utilize components that have a difference in other properties, particularly a difference in Modulus of Elasticity (MOE). Notably, the sleeve can have a MOE that is different than the MOE of the superabrasive layer. Differences in the MOE between the sleeve and superabrasive layer may be utilized to control forces exerted on the superabrasive layer by the sleeve and facilitate improved performance. In particular instances, the cutting elements herein may utilize a difference in MOE between the sleeve and superabrasive layer of at least 5% based on the greater MOE. For example, the percentage difference in MOE can be calculated based on the equation: ((MOE1−MOE2)/MOE1)×100, wherein MOE1≥MOE2. In other embodiments, the difference may be greater, such as on the order of at least about 10%, at least about 25%, at least about 50%, or even at least about 75%. Still, particular embodiments may utilize a difference in MOE between the sleeve and superabrasive layer within a range between about 5% and 75%, such as between 5% and 50%, or even between 5% and 25%. 
     While particular reference above is made to the difference in MOE between the sleeve and the superabrasive layer, it will be appreciated that such differences in MOE may also be employed between other components, particularly between the sleeve and the substrate, the intermediate layer and the substrate, and/or the intermediate layer and the superabrasive layer. 
     The difference in properties noted above may be achieved by utilizing components made of different materials, and, particularly, components having distinct chemical compositions. For example, according to one embodiment, the sleeve and the substrate can be made of a cemented tungsten carbide material. However, the sleeve and the substrate may employ different percentages of certain elements within the components, such as a catalyst material (e.g., cobalt). Such differences can affect mechanical properties such as toughness and abrasiveness. In one particular embodiment, the sleeve is made of cemented tungsten carbide having a content of catalyst material that is at least about 5% lower than the cemented tungsten carbide material of the substrate. 
     Additionally, components herein may have distinct mechanical performance based on differences in microstructure. For example, the sleeve can be formed of a cemented tungsten carbide material formed from a feed material that is distinct from the tungsten carbide feed material used to form the substrate. The feed material can be varied based on parameters such as size distribution of the grains, quality of the grains, and aspect ratio of the grains to affect certain mechanical properties. 
     While reference above is made to the differences in properties between the sleeve and the substrate, such discussion is illustrative and it will be appreciated that such these differences may exists between other components based on a difference in composition and feed material. Particularly, these differences can exist between the intermediate layer and the substrate, and/or the intermediate layer and the sleeve. 
     The cutting elements herein demonstrate a departure from the state of the art. While cutter designs have been disclosed in the past to mitigate problems associated with mechanical strain, temperature-induced strain, and wear, typically the changes in cutter design have been directed to changing the configuration of the cutter table and/or substrate and the interface between these two components. By contrast, the embodiments herein are directed to cutting elements incorporating multiple components employing a cutter body, a sleeve, an intermediate layer, arresting layers, multiple chamfers and/or radiused edges, and for improved performance. Embodiments herein further include a combination of features directed to the orientation between the components, different structures of the components (e.g., layered structures), various materials for use in the components, particular surface features of the components, certain means of affixing the components to each other, and the application of certain types of forces at certain locations between the components. Moreover, the cutting elements of the embodiments herein can be formed through particular forming methods not previously utilized in the art, which facilitate the features of the cutting elements herein. 
     The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description. 
     The Abstract of the Disclosure is provided to comply with Patent Law and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description of the Drawings, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all features of any of the disclosed embodiments. Thus, the following claims are incorporated into the Detailed Description of the Drawings, with each claim standing on its own as defining separately claimed subject matter.