NEAR NET SHAPE POLYCRYSTALLINE DIAMOND CUTTERS AND METHODS OF MAKING THEREOF

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY

[0001] The present disclosure relates generally to polycrystalline diamond cutters and methods of making thereof. Specifically, the present disclosure relates to methods of making near net shape polycrystalline diamond cutters using a shaped refractory cup and/or shaped substrate to form a shaped diamond feed layer that alleviates differences in the propagation of sintering through the diamond feed layer; as well as to near net shape polycrystalline diamond cutters, which can be used in their as-sintered state, or which only need minimal post-sintering processing.

BACKGROUND

[0002] In the discussion that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art against the present invention.

[0003] Tools used in the drilling industry, such as drag bit 100 shown in FIG. 1, often incorporate multiple polycrystalline diamond cutters 200 arranged along a peripheral region of a fin or blade 101 of the drag bit 100. A conventional cylindrical shaped polycrystalline diamond cutter 200 is shown in a schematic, perspective view in FIG. 2A and in a side, cross-sectional view in FIG. 2B. The cutter 200 includes an optional substrate 201 , which is made of hard metal, alloy, or composite, and most typically of cemented carbide or cobalt sintered tungsten carbide (WC-Co); and a polycrystalline diamond composite volume 202, also called a diamond table or diamond body, attached or joined coherently to the substrate along an interface 203.

[0004] Polycrystalline diamond cutters are commonly made using a high pressure and high temperature (HPHT) manufacturing process. In the HPHT manufacturing process, a mass of diamond crystals is placed into a refractory metal container and a cemented carbide substrate is placed in the container such that a surface of the substrate is adjacent to, if not in contact with, the mass of diamond crystals. One or both of the diamond mass and the substrate may contain sintering promoting materials, such as a suitable binder material, additive, or catalyst that promotes sintering of the diamond mass and coherent attachment of the sintered diamond mass to the substrate. When a substrate is present, the binder material of the substrate can act as a catalyst in the diamond powders.

Optionally, a catalyst can also be added as a powder or foil adjacent to the diamond particles, between the substrate and the diamond particles and this catalyst can also promote sintering. An example of a sintering promoting material is cobalt. The refractory metal container, including the diamond crystals and the substrate, form an assembly.

[0005] The assembly is then subjected to HPHT conditions. Conventional HPHT conditions include pressures at or above about 4-5 GPa, and temperatures at or above about 1200 °C. Typically, under the HPHT processing conditions, the sintering promoting materials melt and sweep through the mass of diamond. In the presence of the sintering promoting materials, diamond crystals are bonded to each other in diamond-to-diamond bonds by a dissolution-precipitation process to form a sintered compact in which a polycrystalline diamond mass, i.e., a diamond table, is formed, and which is attached to the substrate (if present). The presence of the sintering promoting materials facilitates formation of diamond-to-diamond bonds and, where applicable, the attachment of the diamond table to the substrate.

[0006] When present in the substrate, e.g., as the binder in the substrate, the sintering promoting material typically melts and propagates into the mass of diamond crystals.

Generally, the binder material of the substrate is selected to function as a catalyst for melting and sintering the diamond crystals. That is, in existing processes for forming a polycrystalline diamond cutter, the cobalt or other binder material from the substrate will melt under HPHT conditions and“sweep" from the carbide substrate, into and across the diamond powder to create the polycrystalline diamond cutter. The sweep propagates as a front that moves from an interface between the substrate and the diamond crystals toward a distal surface of the diamond. With reference to FIG. 2B, the front moves from the interface 203, though the body of the polycrystalline diamond composite volume 202, and toward the top surface 205. In the presence of the liquefied binder material, diamond crystals bond to each other by a dissolution-precipitation process to form a polycrystalline diamond mass attached to the cemented carbide substrate.

[0007] Upon sintering, the sintering promoting material (such as a catalyst), or chemically distinct residues thereof, remain in the diamond table, and its presence can have various effects on the polycrystalline diamond’s overall performance when used in cutting and machining applications. In particular, a nonuniform or incomplete distribution of the catalyst or related residues can have detrimental effects on the mechanical properties of the polycrystalline diamond cutter when used in intended applications, such as drilling geologic formations. A nonuniform or incomplete distribution of the catalyst in the diamond body may, for example, be the result of a sweep that did not reach all the regions of the diamond feed layer, resulting in a diamond body including incompletely or weakly bonded diamond crystals. Detrimental effects include, for example, a less than average useable lifetime for the polycrystalline diamond cutter as reflected in a faster than average wear, or a higher than average propensity for fracturing of the diamond body.

[0008] The polycrystalline diamond cutter 200 may subsequently be machined into a desired shape, including machining to specified outer diameter, height, and/or the addition of various chamfers or beveled surfaces. Examples of chamfers or beveled surfaces 204 can be seen in side view in FIG. 2B, along with other surfaces of the polycrystalline diamond cutter 200, such as the top surface 205, and side surface 206.

The working surface or surfaces of the polycrystalline diamond cutter 200 can be any and all portions of the top surface 205, beveled surface 204, and side surface 206, i.e., any surface of the polycrystalline diamond cutter 200 that contacts the geological formation being drilled.

SUMMARY

[0009] A method of making a near net shape polycrystalline diamond cutter including a substrate and a diamond body is disclosed. In some embodiments, the method includes: forming an assembly including along an axis of the assembly a refractory container, a diamond feed layer, and a substrate; the forming including: providing a refractory container including an inner bottom side, an outer bottom side, and an inner edge side; depositing a layer of diamond feed in the refractory container in contact with the inner bottom side; positioning a substrate over the diamond feed layer, the substrate including a first side and a second side opposite the first side; and, in some cases, positioning a cap over the contents of the refractory container and sealing; and processing the assembly under high pressure high temperature sintering conditions (HPHT) from 5 GPa to 8 GPa, and from 1300 °C to 1600“C, to sinter the diamond feed into a diamond body affixed to the substrate; wherein the second side of the substrate is positioned over the diamond feed layer; and wherein at least one of the inner bottom side of the refractory container and the second side of the substrate includes a convex portion.

[0010] In some embodiments, the inner bottom side of the refractory container includes a convex portion. In some embodiments, the second side of the substrate includes a convex portion. In some embodiments, the convex portion of the substrate or of the refractory container includes one or more of a spherical segment, a frustum of a cone, and a hyperboloid.

[0011] Also, in some embodiments, the maximum thickness of the diamond feed layer, as measured in a direction parallel to the axis of the assembly between the second side of the substrate and the inner bottom side of the refractory container, is at a portion of the diamond feed layer adjacent to the inner edge side of the refractory container. In some embodiments, the minimum thickness of the diamond feed layer, as measured in a direction parallel to the axis of the assembly between the second side of the substrate and the inner bottom side of the refractory container, is at a portion of the diamond feed layer distally radially separated from the inner edge side of the refractory container.

[0012] Other configurations can also be used, including having the thickness of a portion of the diamond feed layer, as measured in a direction parallel to the axis of the assembly between the second side of the substrate and the inner bottom side of the refractory container, vary as a function of radial position; vary at a constant rate as a function of radial position; vary at a variable rate as a function of radial position; vary radially according to a polynomial function; or constant as a function of radial position.

[0013] A polycrystalline diamond cutter is also disclosed. In some embodiments, the polycrystalline diamond cutter includes: a substrate including a first side, a second side opposite the first side, and an edge side connecting the first side to the second side, wherein a periphery of the first side intersects with the edge side, and a portion of the first side is included in a diamond cutter mounting surface; and a diamond body including a first side, a second side opposite the first side, and an edge side connecting the first side to the second side, wherein a periphery of the second side intersects with the edge side and a portion of the second side is included in a diamond body working surface; wherein the first side of the diamond body is attached to the second side of the substrate, wherein the edge side of the diamond body is substantially aligned with the edge side of the substrate along an axis of the cutter; wherein at least a portion of the surface of the concave portion on the second side of the diamond body includes a plurality of exposed sintered diamond particles that retain a physical structure of as-sintered diamond particle.

[0014] In some embodiments, the concave portion extends radially inward from a peripheral region adjacent to the edge side toward the axis of the cutter. In some embodiments, the second side of the diamond body includes a chamfered portion in a peripheral region adjacent to the edge side. In some embodiments, a concave portion includes one or more of a spherical segment, a frustum of a cone, and a hyperboloid. [0015] In some embodiments, the maximum thickness of the diamond body, as measured in a direction parallel to the axis of the cutter between the first side and the second side, is at a portion of the diamond body adjacent to the edge side connecting the first side to the second side. In some embodiments, the minimum thickness of the diamond body, as measured in a direction parallel to the axis of the cutter between the first side and the second side, is at a portion of the diamond body distally radially separated from the edge side connecting the first side to the second side.

[0016] Also, in some embodiments, the thickness of a portion of the diamond body, as measured in a direction parallel to the axis of the cutter between the first side and the second side, varies as a function of radial position; varies at a constant rate as a function of radial position; varies at a variable rate as a function of radial position; varies radially according to a polynomial function; or is constant as a function of radial position.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The foregoing summary, as well as the following detailed description of the embodiments, can be better understood when read in conjunction with the appended drawings. It should be understood that the embodiments depicted are not limited to the precise arrangements and instrumentalities shown.

[0018] FIG, 1 shows an example of a tool used In the drilling Industry, in this case a conventional drag bit.

[0019] FIG. 2A shows a schematic perspective view of a conventional cylindrical shaped polycrystalline diamond cutter, and FIG. 2B shows a conventional cylindrical shaped polycrystalline diamond cutter in cross-sectional view, including optional chamfers or beveled surfaces at an edge of the diamond table.

[0020] FIGS. 3A-3C are schematic representations of a sweep of molten catalyst material moving through a packed bed of polycrystalline diamond particles.

[0021] FIG. 3D shows a cross-sectional schematic of a refractory container having an inner bottom side including a convex portion (or an outer bottom side including a concave portion) and FIG. 3E is a photograph of a cross-sectioned refractory container having an inner bottom side including a convex portion (or an outer bottom side including a concave portion).

[0022] FIG. 4A shows a cross-sectional view of an assembly used in a method of making a near net shape polycrystalline diamond cutter, the assembly including a refractory container, a diamond feed layer, and a substrate, the refractory container having an inner bottom side Including a convex portion protruding into the diamond feed layer.

[0023] FIGS. 4B, 4C, 4D, and 4E shows, in cross-section, various alternative shapes that a portion (Portion D in FIG. 4A) of the interface between the substrate and the diamond feed layer can have.

[0024] FIG. 4F shows a cross-sectional view of another embodiment of an assembly used in a method of making a near net shape polycrystalline diamond cutter, the assembly including a refractory container, a diamond feed layer, and a substrate, the refractory container having an inner bottom side including a convex-like portion that includes a complex surface that includes surfaces of different angles relative to the axis.

[0025] FIG. 4G shows a cross-sectional view of another embodiment of an assembly used in a method of making a near net shape polycrystalline diamond cutter, the assembly including a refractory container, a diamond feed layer, a substrate, and an insert at the bottom of the refractory container, the insert including a convex portion protruding into the diamond feed layer.

[0026] FIG. 4H shows a cross-sectional view of an embodiment of an assembly used in a method of making a near net shape polycrystalline diamond cutter, the assembly including a refractory container, a diamond feed layer, and a substrate, the substrate side adjacent to the diamond feed layer including a convex portion protruding into the diamond feed layer.

[0027] FIGS. 5A, 5B, and 5C show cross-sectional views of several embodiments of an assembly during a sweep-through HPHT sintering process; the arrows indicate the general directions of the catalyst sweep through the diamond feed layer.

[0028] FIG. 6A shows a cross-sectional view of a first embodiment of a polycrystalline diamond cutter Including a substrate and diamond body, the end of the diamond body, distally axially separated from the substrate, including a concave portion. The dotted lines indicate various planar, cylindrical, conical, or hyperboloid surfaces along which the as- sintered diamond cutter can be finish machined by laser cutting, electrical discharge machining, grinding, lapping, and/or polishing; but this finish processing does not extend to the concave portion, and, therefore, at least a portion of the exposed sintered diamond particles on the surface of the concave portion retains the physical structure of the as- sintered diamond particles.

[0029] FIG. 6B shows a cross-sectional view of a second embodiment of a polycrystalline diamond cutter including a substrate and diamond body, the end of the diamond body, distally axially separated from the substrate, including a concave portion. The dotted lines indicate various planar, cylindrical, conical, or hyperboloid surfaces along which the as- sintered diamond cutter can be finish machined by laser cutting, electrical discharge machining, grinding, lapping, and/or polishing; but this finish processing does not extend to the concave portion, and, therefore, at least a portion of the exposed sintered diamond partides on the surface of the concave portion retains the physical structure of the as- sintered diamond particles.

[0030] FIG. 7 shows a cross-sectional view of polycrystalline diamond cutter including a substrate and diamond body, the substrate side adjacent to the diamond body including a convex portion protruding into the diamond body. The dotted lines indicate various planar, cylindrical, conical, or hyperboloid surfaces along which the as-sintered diamond cutter can be finish machined by laser cutting, electrical discharge machining, grinding, lapping, and/or polishing.

DETAILED DESCRIPTION

[0031] The disclosure relates to methods of making near net shape polycrystalline diamond cutters, as well as to near net shape polycrystalline diamond cutters, which can be used in their as-sintered state, or which only need minimal post-sintering processing compared to cutters made by traditional methods. In general, methods of manufacture include forming an assembly for subsequent high pressure - high temperature (HPHT) processing during which polycrystalline diamond particles, with the aid of a sintering promoting material, such as a catalyst, are consolidated and sintered into a diamond body that is bonded to the substrate. [0032] Without wishing to be bound by any particular theory, it is believed that during

HPHT sintering process, a front of molten catalyst material sweeps or moves from an interface between the substrate and the diamond crystals toward a region of the diamond feed layer distally separated from the interface (FIGS. 3A-3C), where distally separated means both spatially separated from and at a distance from a reference location. As shown in FIG. 3A, prior to any movement of molten sintering promoting material from its source, for example, the binder material in the substrate, the compressed diamond crystals 300 are in intimate direct contact with their nearest neighbors according to their ability to pack together under high pressure. The packing is not complete because the diamond crystals 300 are resistant to total crushing. The pre-sweep condition therefore includes open spaces 302 between the diamond crystals 300. Such open spaces 302 are subsequently filled with the molten sintering promoting material 304 as the sweep front 306 passes them (See FIGS. 3B and 3C).

[0033] As used herein, a“front" refers to the movement of molten sintering promoting material, such as molten catalyst material, through the diamond feed layer, that is, between and around the diamond crystals, filling in the spaces between the diamond crystals (see FIGS. 3B and 3C). It also refers, in some contexts, to a moving boundary between the unfilled spaces and the spaces filled with molten material.

[0034] Also without wishing to be bound by any particular theory, It Is believed that depending on various conditions such as the geometry of the refractory cup, the substrate, and/or the diamond feed layer, or because of the particular nature of the sintering promoting material and/or the diamond particles, the front can be uniform, or non-uniform. As used herein, and without wishing to be bound by any particular theory, the uniformity of a sweep front relates to the speed at which the molten sintering promoting material or the boundary or interface between molten and non-molten sintering promoting material advances through the assembly and the components located within the assembly. For example, a non-uniform front may result when the speed of the catalyst material is higher in a region of the diamond feed layer adjacent to the side walls of the refractory cup, comparative to a lower speed of the catalyst material in a region of the diamond feed layer adjacent to a central axis of the assembly including the refractory cup, the substrate, and the diamond feed layer. Because of this speed differential, it is also believed, without wishing to be bound by any particular theory, that in a conventional sweep-through HPHT process using a relatively flat bottomed refractory cup, and a relatively fiat interface between the substrate and the diamond feed layer, the sweep front will arrive faster at the portion of the diamond composite volume adjacent to the walls of the refractory cup, comparative to a slower arrival of the sweep front at a portion of the diamond composite volume in the region of the central axis of the refractory cup, i.e distal from the walls of the refractory cup.

[0035] Also without wishing to be bound by any particular theory, it is believed that as a result of the difference in the speed of the sweep-through front, the sintered diamond body may include structural differences between the various parts thereof where the sweep-through front arrived at different times, which further result in different and nonuniform mechanical performance of the various parts of the diamond body. For example, the diamond body may include portions where the sweep did not reach the diamond feed layer, resulting in incomplete sintering or resulting in gaps between the diamond particles, such portions having a higher rate of wear and higher propensity to fracture compared to the rest of the diamond body. The diamond body can be further finished to remove the parts of the diamond body with these less than desirable mechanical properties resulted from the non-uniform sweep, but at the expense of disposing of large portions of the as-sintered diamond body.

[0036] Thus, it is beneficial to provide a sweep-through HPHT sintering method to alleviate the non-uniformity of propagation of the sweep front through the diamond body.

In some embodiments, the method includes providing a shaped refractory cup and/or shaped substrate, and by implication a shaped diamond feed layer, that allows for alleviating the differences in the speed of the sweep front through the diamond feed layer, and minimal differences in the arrival time of the sweep front at the bottom of the refractory cup. This sweep-through HPHT sintering results in an as-sintered diamond body having improved mechanical properties such as resistance to wear and low propensity to fractures. To the extent that further finishing of the diamond body is desired, for example by grinding, lapping, and/or polishing, such finishing is minimal and is done without removing large portions of the diamond body, but rather very small portions, because, as described herein, the method allows for the isolation of potential gaps in the distribution of the catalyst material in small and spatially focused regions of the diamond body.

[0037] In some embodiments, the method of making a near net shape polycrystalline diamond cutter including a substrate and a diamond body includes forming an assembly including (along an axis of the assembly) a refractory container, a diamond feed layer, and a substrate. In some embodiments, the forming of the assembly includes providing a refractory container including an inner bottom side, an outer bottom side, and an inner edge side; depositing a layer of diamond feed in the refractory container in contact with the inner bottom side; positioning a substrate over the diamond feed layer, the substrate including a first side and a second side opposite the first side; sealing the container, for example, by positioning a cap over the contents of the refractory container and sealing the container; and processing the assembly under high pressure high temperature sintering conditions (HPHT) from 5 GPa to 8 GPa, and from 1300 °C to 1600 ⁶ C, to sinter the diamond feed into a diamond body affixed to the substrate; wherein the second side of the substrate is positioned over the diamond feed layer; and wherein at least one of the inner bottom side of the refractory container and the second side of the substrate includes a convex portion.

[0038] An exemplary refractory container having an inner bottom side including a convex portion is as shown in FIG. 3D, which depicts a cross-sectional schematic of such a refractory container 310 having an inner bottom side including a spherical segment convex portion (or an outer bottom side Including a concave portion). FIG. 3E is a photograph of a cross-sectioned refractory container 310 having an inner bottom side including a convex portion (or an outer bottom side including a concave portion). In some embodiments, the convex portion of the refractory container 310 includes one or more of a spherical segment, a frustum of a cone, and a hyperboloid.

[0039] The refractory container 310 is typically made from a refractory alloy including one or more metals such as tantalum (Ta), niobium (Nb), molybdenum (Mo), and/or zirconium

(Zr). In some embodiments, tantalum is a preferred material. The refractory container 310 can be made by any suitable method. In some embodiments, the refractory container 310 is seamless and is formed by a sheet metal forming process that includes a drawing operation, for example deep drawing. When a convex or concave portion is present, it also can be formed by a sheet metal forming process that includes a drawing operation, for example deep drawing.

[0040] An assembly 400, 420, 450, 470 can be formed in one of several ways.

[0041] For example, and as shown in FIG. 4A, a layer of diamond feed 403 is placed in a refractory container 401 having an inner bottom side 409 including a convex portion

402. Layer 403 can be formed by pouring or otherwise adding the diamond feed into the interior volume of the refractory container 401. The diamond feed 403 is distributed in a layer on the bottom of the refractory container 401 and has a desired distribution and thickness. In some embodiments, the diamond feed 403 is distributed in a variable thickness layer of between 1 mm and 5 mm. A carbide or other suitable substrate 404 is thereafter placed with its second side 408 on the diamond feed layer 403, creating a relatively planar interface 405. In the example assembly 400 shown in FIG.4A, both sides of substrate 404 are generally planar and the diamond feed layer is shaped, on a first side, in conformity to the shape of a side of the substrate 404 and, on a second side, in conformity to the shape of the inner bottom side of the refractory cup 401, which has a convex portion 402 protruding into the diamond layer 403. In some embodiments, the convex portion 402 of the refractory container includes one or more of a spherical segment, a frustum of a cone, and a hyperboloid.

[0042] As described herein, the refractory container 401 , and by implication the assembly

400, include sweep convergence reservoirs 406 (FIG. 4A, detail "A"), which are generally the lowest portions of the refractory cup, occupying a relatively low fraction of the volume of the lower part of the refractory container. [0043] In some embodiments, the maximum thickness of the diamond feed layer, as measured in a direction parallel to the axis of the assembly between the second side of the substrate and the inner bottom side of the refractory container, is at a portion of the diamond feed layer adjacent to the inner edge side of the refractory container. In other embodiments, the minimum thickness of the diamond feed layer, as measured in a direction parallel to the axis of the assembly between the second side of the substrate and the inner bottom side of the refractory container, is at a portion of the diamond feed layer distally separated from the inner edge side of the refractory container. As shown in

FIG. 4A for example, the convex portion 402 of the inner bottom side of refractory cup

401 , protrudes into the diamond feed layer 403, resulting in the layer 403 having a relatively higher thickness in a region adjacent to the inner edge side of the refractory container 401 , and a relatively lower thickness in a region dose to the center of the diamond feed layer 403 adjacent to axis 407. As shown In FIG. 4A for example, detail

“D”, the thickness of the diamond feed layer 403 in a portion Έ" closer to the axis 407, is smaller than the thickness of the diamond feed layer 403 in a portion“C” radially distally separated from the axis 407.

[0044] In some embodiments, a portion of the substrate and a portion of the refractory container are substantially cylindrical and the thickness of a portion of the diamond feed layer, as measured in a direction parallel to the axis of the assembly between the second side of the substrate and the inner bottom side of the refractory container, varies as a function of radial position. For example, in some embodiments, the thickness of the diamond feed layer increases in a radial direction from the axis of the assembly toward the walls of the refractory container. [0045] Without wishing to be bound by any particular theory or embodiment, any convex and concave diamond feed layer, or refractory cup portions described herein, can take any convex and/or concave shape or form as described for example by reference to the shape or form of its cross-section. For example, the convex portion 402 as described for example in FIG. 4A, can take any shape or form, for example as described by the shape of a portion of its cross-section (see FIGS. 4A, 4B, 4C, 4D, and 4E, detail“D").

[0046] In some embodiments, the thickness of a portion of the diamond feed layer, as measured in a direction parallel to the axis of the assembly between the second side of the substrate and the inner bottom side of the refractory container, varies at a constant rate as a function of radial position. For example, the thickness of the diamond feed layer increases at a constant rate in a radial direction from the axis of the assembly toward the walls of the refractory container. As shown in FIG. 4B for example, the cross-section of a convex portion can include a straight line 410 at an angle to interface 405, therefore the thickness increases at a constant rate (FIG. 4B, detail“D").

[0047] In other embodiments, the thickness of a portion of the diamond feed layer, as measured in a direction parallel to the axis of the assembly between the second side of the substrate and the inner bottom side of the refractory container, varies at a variable rate as a function of radial position. For example, the thickness of the diamond feed layer increases at a variable rate in a radial direction from the axis of the assembly toward the walls of the refractory container. As shown in FIG. 4C for example, the cross-section of a convex portion can include two straight lines 412 at an angle to each other, and at an angle to interface 405, therefore varying the rate at which the thickness increases (FIG.

4C, detail“D”). Similarly, as shown in FIG. 4D, the cross-section of a convex portion can include a curve 414 also varying the rate at which the thickness increases (FIG. 4D, detail

“D").

[0048] In still other embodiments, the thickness of a portion of the diamond feed layer, as measured in a direction parallel to the axis of the assembly between the second side of the substrate and the inner bottom side of the refractory container, varies radially according to a polynomial function. For example, the thickness of the diamond feed layer increases according to a polynomial function in a radial direction from the axis of the assembly toward the walls of the refractory container. The curve 414 shown in FIG. 4D is an example of a surface that varies as a polynomial function, but other polynomial functions can also be used. For example, a function y = ox ² + bx + c can be used.

[0049] In still other embodiments, the thickness of a portion of the diamond feed layer, as measured in a direction parallel to the axis of the assembly between the second side of the substrate and the inner bottom side of the refractory container, is constant as a function of radial position. For example, the thickness of the diamond feed layer is constant in a radial direction from the axis of the assembly toward the walls of the refractory container. As shown in FIG. 4E for example, the cross-section of a convex portion can include a straight line 416 parallel to the cross-section of the interface 405

(FIG. 4B, detail“D”).

[0050] In still further embodiments, the inner bottom side of the refractory container can have a convex-like portion that includes a complex surface but retains an overall convex character across the area of the inner bottom side. For example, an assembly 420 can also be formed as shown in FIG. 4F along an axis 427. A layer of diamond feed 423 is located in a refractory container 421 having an inner bottom side 429 including a convex- like portion 422 that includes a complex surface. The layer 423 can be formed by pouring or otherwise adding the diamond feed into the interior volume of the refractory container

421. The diamond feed 423 is distributed in a layer on the bottom of the refractory container 421 and has a desired distribution and thickness, for example, is distributed in a variable thickness layer of between 1 mm and 5 mm. A carbide or other suitable substrate 424 is thereafter placed with its second side 428 on the diamond feed layer 423 creating an interface 425.

[0051] In the illustrated example, the complex surface of the convex-like portion 422 includes surfaces 430 of different angles relative to the axis 427. As a result, the complex surface includes portions that project toward the interior volume of the refractory container

(e.g., surface 432a) and portions that project away from the interior volume of the refractory container (e.g., surfaces 432b), but nonetheless, the overall character of the shape of the inner bottom side 429 is convex (when considered, in cross-sectional view, from a first end 432 of the inner bottom side 429 to a second end 434 of the inner bottom side 429).

[0052] Note, that optionally the angular positioning of at least some of the surfaces 430 of the convex-like portion 422 of the inner bottom side 429 can mirror the surfaces of the second side 428 of the substrate 424. In some embodiments, this mirroring can result in a diamond feed layer 423 having a constant thickness In that region (as measured in a direction parallel to the axis of the cutter between the first side and the second side).

[0053] An assembly 450 can also be formed as shown in FIG. 4G along an axis 457. In some embodiments, a variable thickness diamond feed layer 455 can be prepared in an otherwise relatively planar inner bottom side refractory cup 451 , by using an insert 453 having a convex portion 454. Layer 455 can be formed by pouring or otherwise adding the diamond feed into the interior volume of the refractory container 451 that includes insert 453 sitting on the flat end 452 of container 451. The diamond feed 455 is distributed in a layer over insert 453, and has a desired distribution and thickness. Thus, for purposes of creating a variable thickness diamond feed layer 455, the convex portion 454 of insert

453 functions as an inner bottom side of the refractory cup having a convex portion. In some embodiments, the diamond feed 455 is distributed in a variable thickness layer of between 1 mm and 5 mm. A carbide or other suitable substrate 456 is thereafter placed on the diamond feed layer 455, typically with the second side 459 toward the diamond feed layer 455. In some embodiments, the use of an insert 453 having a convex portion

454, positioned at the relatively planar bottom of refractory cup 451 , results in a diamond feed layer 455 having a relatively higher thickness close to the inner walls of container

451 , compared to the center portion of the layer adjacent to axis 457. As described herein, assembly 450 includes sweep convergence reservoirs 458 (FIG. 4G, detail“A"), which are generally the lowest portions of the volume created between the refractory cup 451 and insert 453, the reservoirs occupying a relatively low fraction of the volume.

[0054] Each of the described assemblies 420, 450 are similar to assembly 400 in that (i) each assembly 400, 420, 450 produces a near net shape similar to the concave surface and (li) the as-pressed concave surface of the diamond body formed using each assembly

400, 420, 450 is formed near net shape and not subject to finish machining.

[0055] In other embodiments, a variable thickness diamond feed layer can be prepared in an otherwise relatively planar inner bottom side refractory cup 471 , by using a substrate

473 having a convex portion 475 (FIG. 4H). As shown in FIG. 4H, an assembly 470 can include, along an axis 477, a refractory cup 471 having a relatively flat inner bottom side

478, a diamond feed layer 472 which has been poured into the cup 471 , and a substrate

473. The side 474 of the substrate 473 adjacent to the diamond feed layer 472, has a convex portion 475 which protrudes into the diamond feed layer 472. In some embodiments, the convex portion 475 of the substrate 473 includes, for example, one or more of a spherical segment, a frustum of a cone, and a hyperboloid. The use of a substrate 473 including a convex portion 475, results in a diamond feed layer 472 having a relatively higher thickness close to the inner walls of container 471 , compared to the center portion of the layer 472 adjacent to axis 477. As described herein, assembly 470 can include sweep convergence reservoirs 476 (FIG. 4H, detail“A"), which are generally the lowest portions of the refractory cup 471 , and occupying a relatively low fraction of the volume of the cup.

[0056] All substrates described herein can be any suitable substrates that can be processed in the high pressure - high temperature sintering environment used to consolidate and sinter the polycrystalline diamond particles into the diamond body and to bond the diamond body to the substrate. For example, the composition of the substrate typically includes a catalyst. In exemplary embodiments, the substrate is a hard metal alloy or composite, a cemented carbide, or cobalt sintered tungsten carbide (WC-Co). In some embodiments, the substrate is or includes cobalt sintered tungsten carbide and has a composition of 8-15 wt.% cobalt and 85-92 wt.% tungsten carbide and, optionally, 0.3-

2.5 wt.% chromium.

[0057] In general, the substrate can be manufactured to final shape or near final shape prior to use in the high pressure - high temperature manufacturing operation. For example, the substrate can be formed substantially in the shape of a solid body, such as any type of cylinder or any type of polyhedron. In some embodiments, a convex portion can be manufactured in the solid body by green body pre-forming, or machining.

Especially in the case of complex geometries for the substrate or for the convex portion of the substrate, powder metallurgy techniques can be used to form a green body with near net shape geometry and then the substrate can be machined to final form before being processed in the high pressure - high temperature sintering environment used to consolidate and sinter the polycrystalline diamond particles into the diamond body and to bond the diamond body to the substrate.

[0058] In some embodiments, assemblies can include solid catalyst, such as a foil or metal disc, placed at the bottom of the substrate opposite the diamond feed layer- substrate interface. A typical catalyst solid is a cobalt or cobalt alloy metal disc. The metal body is in direct contact with a portion of the diamond feed, and during the HPHT processing sweeps along an axis of the assembly through the diamond feed layer. This typically occurs prior to the binder sweep from the substrate. The infiltration of catalyst metal from two sources - binder in the substrate and catalyst in foil or disc - contributes to attachment of the diamond body to the substrate. The catalyst solid can be incorporated into any of the assemblies disclosed herein whether using a refractory container having an inner bottom side Including a convex portion protruding into the diamond feed layer, or a substrate having a convex portion protruding into the diamond feed layer.

[0059] Sealing can be by any suitable means that secures the components and contents in the refractory container. For example, portions of the ends of the cup can be crimped over the substrate surface. Also for example, a cap, typically of the same material as the refractory container, can optionally be placed over the formed assembly, to cover the contents of the refractory container before sealing. Thus, portions of the container itself

(or the container and the cap, if present) can be crimped or otherwise pressed together so as to seal the components and form an assembly. When used, the cap can be a disc or foil or similar planar structure that is placed over the opening of the container and its content, and then the peripheral edge of the cap and the peripheral edge of the opening of the container are crimped or otherwise pressed together or folded over so as to seal the cap and the container to form a capped assembly. The cap is typically of the same material as the refractory container, e.g., tantalum.

[0060] Assemblies formed as described herein can be processed under high pressure - high temperature (HPHT) processing conditions. One or more assemblies are loaded into a cell for high pressure - high temperature (HPHT) processing. Generally, the cell includes a gasketing material which transmits pressure and retains the contents of the cell under pressure, a heating element the assemblies, and insulating materials. An example of a suitable cell is disclosed in U.S. Patent No. 4,807,402, the entire contents of which are incorporated herein by reference. The cell is then subjected to high pressure

- high temperature (HPHT) processing conditions sufficient to consolidate and sinter the diamond feed into a diamond body that is bonded to the substrate. An example of suitable

HPHT processing conditions includes pressures in the range of about 5 GPa to about 10

GPa and temperatures in the range of about 1100 °C to about 2000 °C for times up to

20-30 minutes. Conditions favorable for the present methods and structures fall within about 5 GPa to about 8 GPa and about 1300 °C to about 1700 °Cfor about 12-18 minutes. [0061] The HPHT sintering methods described herein include a sweep-through step of molten catalyst through the diamond feed layer, the sweep including a front of catalyst generally moving from the interface between the substrate and the diamond feed layer, toward the bottom of the refractory container. As described herein, the diamond feed layer is formed with a variable thickness, a feature which alleviates any discrepancies between the relative speed of the sweep through various portions of the diamond feed layer, ensuring that the sweep reaches the bottom of the refractory container at generally the same time across its entire surface, and/or cross-section.

[0062] As shown for example in FIG. 5A (with respect to the assembly as shown and described in FIG. 4A), the sweep can move faster through a region of the diamond feed layer 503 adjacent to the container's inner walls, and slower through a region of the diamond feed layer 503 adjacent to the central axis 507 of the assembly 500. Because of the convex portion 502 of the inner bottom side of the refractory container, the diamond feed layer 503 is relatively thicker at the region of the diamond feed layer adjacent to the container's inner walls, and thinner at the region of the diamond feed layer adjacent to the central axis 507 of the assembly 500. Therefore, even though the sweep is faster through the peripheral region of the diamond feed layer and slower through the region adjacent to the axis, the sweep reaches the convex inner bottom side 502 of container

501 at relatively the same time across its entire surface or cross-section. The sweep then converges in sweep convergence reservoirs 506 (FIG. 5, detail“A"), which are generally the lowest portions of the refractory cup, occupying a relatively low fraction of the volume of the lower part of the refractory container. Without wishing to be bound by any particular theory, it is believed that any residual discrepancy in the quality and/or uniformity of the sweep penetration through the diamond feed layer is isolated to the relatively smaller volume of the sweep convergence reservoirs 506. Please note that the theorized sweep in FIG. 5A is only shown in the volume on one side of the axis 507 of the assembly 500, but it should be understood that a similar theorized sweep is present in the volume on the other side of the axis 507 of the assembly 500.

[0063] As further shown in FIG.5B (with respect to the assembly as shown and described in FIG. 4G), the sweep can move faster through a region of the diamond feed layer 555 adjacent to the container's inner walls, and slower through a region of the diamond feed layer 555 adjacent to the central axis 557 of the assembly 550. Because of the convex portion 554 of insert 553, the diamond feed layer 555 is relatively thicker at the region of the diamond feed layer adjacent to the container 551 inner walls, and thinner at the region of the diamond feed layer adjacent to the central axis 557 of the assembly 550. Therefore, even though the sweep is faster through the peripheral region of the diamond feed layer and slower through the region adjacent to the axis, the sweep is reaching the convex portion 554 of insert 553 at relatively the same time across its entire surface or crosssection. The sweep then converges in sweep convergence reservoirs 556, occupying a relatively low fraction of the lower volume of the refractory container. Without wishing to be bound by any particular theory, it is believed that any residual discrepancy in the quality and/or uniformity of the sweep penetration through the diamond feed layer is isolated to the relatively smaller volume of the sweep convergence reservoirs 556. Please note that the theorized sweep in FIG. 5B is only shown in the volume on one side of the axis 557 of the assembly 550, but it should be understood that a similar theorized sweep is present in the volume on the other side of the axis 557 of the assembly 550. [0064] A similar theorized sweep to that depicted and described with respect to FIGS.

5A and 5B also exists with respect to the assembly 420 shown and described in FIG. 4F.

In the FIG. 4F embodiment, the sweep converges in sweep convergence reservoirs 438, occupying a relatively low fraction of the lower volume of the refractory container.

[0065] Assembly 570 in FIG. 5C can be used in an HPHT sintering method as described herein. For example and with respect to the assembly as shown and described in FIG.

4H, the sweep starting at the interface between side 574 of the substrate, can move faster through a region of the diamond feed layer 572 adjacent to the container 571 inner walls, and slower through a region of the diamond feed layer 572 adjacent to the central axis

577 of the assembly 570. However, because of the convex portion 575, the diamond feed layer 572 is relatively thicker at the region of the diamond feed layer adjacent to the container 571 inner walls, and thinner at the region of the diamond feed layer 572 adjacent to the central axis 577 of the assembly 570, and thus the sweep is reaching the bottom of the container at relatively the same time across its entire surface or cross-section. The sweep then converges in sweep convergence reservoirs 576, which occupy a relatively low fraction of the lower volume of the refractory container. Without wishing to be bound by any particular theory, it is believed that any residual discrepancy in the quality and/or uniformity of the sweep penetration through the diamond feed layer is isolated to the relatively smaller volume of the sweep convergence reservoirs 576. Please note that the theorized sweep in FIG. 5C is only shown in the volume on one side of the axis 577 of the assembly 570, but it should be understood that a similar theorized sweep is present in the volume on the other side of the axis 577 of the assembly 570. [0066] The methods described herein can further include finishing steps or finish machining of the diamond body to final form. Such processing can include finish wire shaping or grinding of the surfaces of the diamond body, lapping or grinding of the diamond body to planarize some portions of the top surface of the diamond body, grinding to add a bevel or chamfer to the diamond body and/or substrate, rotational grinding to finish grind the cylindrical sides of the cutter, and leaching of the catalyst in one or more portions of the diamond body. In some embodiments, the methods include finish machining the diamond body. In some embodiments, finish machining includes one or more of laser cutting, electrical discharge machining, grinding, lapping, and polishing.

[0067] In some embodiments, the method further includes leaching a portion of the sintered diamond body to form interstitial regions substantially free of catalyst material or sintering residue thereof. Interstitial regions are microstructural features of the sintered diamond body that refers to the spaces within the matrix phase of the sinter bonded polycrystalline diamond material typically occupied by a catalyst material like Co and/or fillers upon formation of the sintered diamond body using HPHT techniques and which form empty spaces, pores or voids as a result of the catalyst material being removed therefrom in, for example, a subsequent leaching step. In some embodiments, the diamond body portion including interstitial regions substantially free of catalyst material or sintering residue thereof extends from a working surface Into an interior volume of the diamond body. Removal of catalyst from the diamond body, particularly from portions of the diamond body that act as a working surface of the polycrystalline diamond cutter leaves interconnected network of pores and a residual catalyst (up to 10 vol.%) trapped inside the polycrystalline diamond body. In some embodiments, the removal of catalyst, such as cobalt, from diamond bodies improves abrasion resistance of the diamond body.

Such leaching can occur in at least a portion of the diamond body and renders the diamond body in that portion substantially free of catalyst material. Leaching can occur, for example, by chemical etching in acids in which portions to be leached are exposed to an acid or a mixture of acids, such as aqua regia, for a period of time sufficient to dissolve the catalyst material to a depth from the surface of the diamond body. The time varies by strength of acid, temperature and pressure as well as the desired depth. Exemplary depths from which the catalyst material has been removed range from 50 microns to 800 microns, alternatively less than 300 microns or less than 200 microns or less than 100 microns. Also, for example, the depth may be at least half of the overall thickness of the diamond body, but the depth is no closer to the interface between the lower side of the diamond body and the upper side of the substrate than about 200 microns. Descriptions of leaching and of leached polycrystalline diamond cutters are contained In, for example,

U.S. Patent No. 4,224,380; U.S. Patent No. 6,544,308 and U.S. Patent No. 8,852,546, the entire contents of each are incorporated herein by reference.

[0068] As noted early, the disclosure also relates to a polycrystalline diamond cutter per se. In some embodiments, the polycrystalline diamond cutter includes a substrate including a first side, a second side opposite the first side, and an edge side connecting the first side to the second side, wherein a periphery of the first side intersects with the edge side, and a portion of the first side is included in a diamond cutter mounting surface; and a diamond body including a first side, a second side opposite the first side, and an edge side connecting the first side to the second side, wherein a periphery of the second side intersects with the edge side and a portion of the second side is included in a diamond body working surface; wherein the first side of the diamond body is attached to the second side of the substrate, wherein the edge side of the diamond body is substantially aligned with the edge side of the substrate along an axis of the cutter; wherein the second side of the diamond body includes a concave portion, and wherein at least a portion of the surface of the concave portion on the second side of the diamond body includes a plurality of exposed sintered diamond particles that retain a physical structure of as-sintered diamond particle.

[0069] An exemplary polycrystalline diamond cutter 600 is shown in FIG. 6A. The cutter includes (along an axis 608) a substrate 601 , and a diamond body 602. In some embodiments, the second side 610 of the diamond body 602 includes a concave portion

603 extending radially inward from a peripheral region 611 adjacent to the edge side 612 toward the axis 608 of the cutter. In some embodiments, the concave portion 603 of the diamond body 602 has the general shape of the convex portion of the inner bottom side of the refractory container used to make the cutter. The first side 613 of the diamond body

602 attached to the substrate 601 is relatively planar, being attached to the likewise relatively planar side 614 of the substrate 601 , although other geometries can also be used.

[0070] In some embodiments, the second side 610 of the diamond body 602 includes a planar portion 609 substantially perpendicular to the axis of the cutter 600. In some embodiments, the planar portion 609 is at the peripheral region 611 adjacent to the edge side 612. In some embodiments, the peripheral planar portion 609 can result from the sintering in a correspondingly shaped refractory container, but also from further machining of the diamond body. [0071] In some embodiments, the maximum thickness of the diamond body, as measured in a direction parallel to the axis of the cutter between the first side and the second side, is at a portion of the diamond body adjacent to the edge side connecting the first side to the second side. In some embodiments, the thickness of the diamond body increases radially from the axis of the cutter toward an outer edge of the diamond body.

In some embodiments, the minimum thickness of the diamond body, as measured in a direction parallel to the axis of the cutter between the first side and the second side, is at a portion of the diamond body distally separated from the edge side connecting the first side to the second side.

[0072] As shown in FIG. 6A for example, the maximum thickness of the diamond body

602, as measured in a direction parallel to the axis 608 of the cutter between the first side

613 of the diamond body 602 and the second side 610 of the diamond body 602 including concave portion 603, is at a portion 611 of the diamond body 602 adjacent to the edge side 612 connecting the first side 613 to the second side 610. The minimum thickness of the diamond body 602, as measured in a direction parallel to the axis 608 of the cutter

600 between the first side 613 and the second side 610 including concave portion 603, is at a portion 615 of the diamond body 602 distally radially separated from the edge side

612 connecting the first side 613 to the second side 610, and adjacent to axis 608. Other variations as described herein (see, e.g., FIGS. 4B to 4E) can also be used.

[0073] In some embodiments, a portion of the edge side of the diamond body and the edge side of the substrate are cylindrical. In some embodiments, the thickness of a portion of the diamond body, as measured in a direction parallel to the axis of the cutter between the first side and the second side, varies as a function of radial position. In some embodiments, the thickness increases radially in a direction from the axis of the polycrystalline cutter toward an outer circumference of the polycrystalline cutter. As shown in FIG. 6A detail“D" for example, the thickness of the diamond body in a portion

“B" closer to the axis 608, is smaller than the thickness of the diamond body in a portion

"C" radially distally separated from the axis 608.

[0074] Without wishing to be bound by any particular theory or embodiment, any convex and/or concave diamond body or substrate portions described herein, can take any convex and/or concave shape or form as described herein as to the shape or form of diamond feed layers and refractory cups. Similarly, without wishing to be bound by any particular theory or embodiment, the manner and direction of thickness variation of a diamond body portion are as described herein as to the manner and direction of thickness variation of a diamond feed layer. The manner and direction of thickness variation in a diamond body include a) increase at a constant rate radially in a direction from the axis of the polycrystalline cutter toward an outer circumference of the polycrystalline cutter; b) increases radially at a variable rate in a direction from the axis of the polycrystalline cutter toward an outer circumference of the polycrystalline cutter; c) increase according to a polynomial function radially in a direction from the axis of the polycrystalline cutter toward an outer circumference of the polycrystalline cutter; and/or d) remain constant as a function of radial position. For example a function y - ax ² + bx + c can be used. In some embodiments, a convex and/or concave portion of a diamond body described herein includes one or more of a spherical segment, a frustum of a cone, and a hyperboloid.

[0075] The features and geometry of the substrate and the diamond body that form the polycrystalline diamond cutter can vary, and the various embodiments of the polycrystalline diamond cutter can be further processed to final form. Such processing can include finish wire shaping or grinding of the surfaces of the passage, lapping or grinding of the diamond body to planarize the top surface of the grinder, grinding to add a bevel or chamfer to the diamond body and/or substrate, rotational grinding to finish grind the cylindrical sides of the cutter, and leaching of the catalyst in one or more portions of the diamond body.

[0076] In some embodiments, further processing includes machining along various surfaces, including planar, cylindrical, or hyperboloid surfaces. For example, and as shown in FIG. 6A and as represented by various dashed lines, a diamond cutter 600 including the as-sintered diamond body 602, can be machined to: i) reduce the height of the substrate by machining along plane 605; ii) reduce the overall diameter and/or circumference of the cutter by machining along cylinder 604; iii) reduce the height of the diamond body by machining along plane 606; and/or iv) add chamfered and/or beveled surfaces by machining along the frustum of cone 607. Such machining generally removes the mass of the diamond body 602 that includes the sweep convergence reservoirs, such as the peripheral protuberances 620 having the general shape of sweep convergence reservoirs present in the refractory containers used to make the cutter.

[0077] Another exemplary polycrystalline diamond cutter 700 is shown in FIG. 7, the cutter Including, along an axis 709, a substrate 701 , and a diamond body 702, In some embodiments, the first side 710 of the diamond body 702 includes a concave portion 704 extending radially inward from a peripheral region 711 adjacent to the edge side 712 toward the axis 709 of the cutter. In some embodiments, the concave portion 704 of the diamond body 702 has the general shape of, and envelopes the convex portion 704 of the second side 715 of substrate 701. In some embodiments, the second side 703 of the diamond body 702 is substantially planar, although it can include peripheral protuberances 713 having the general shape of sweep convergence reservoirs present in the refractory containers used to make the cutter.

[0078] The maximum thickness of the diamond body 702, as measured in a direction parallel to the axis 709 of the cutter 700 between the first side 710 including concave portion 704, and the second side 703, is at a region 711 of the diamond body 702 adjacent to the edge side 712 connecting the first side 710 to the second side 703. The minimum thickness of the diamond body 702, as measured in a direction parallel to the axis 709 of the cutter between the first side 710 including concave portion 704, and the second side

703, is at a portion 714 of the diamond body distally radially separated from the edge side

712 connecting the first side to the second side and adjacent to axis 709.

[0079] For example and as shown In FIG. 7 and as represented by various dashed lines, diamond cutter 700, including the as-sintered diamond body 702, can be machined to: i) reduce the height of the substrate by machining along plane 706; ii) reduce the overall diameter and/or circumference of the cutter by machining along cylinder 705; iii) reduce the height of the diamond body by machining along plane 707; and/or iv) add chamfered and/or beveled surfaces by machining along the frustum of cone 708. Such machining generally removes the mass of the diamond body 702 that includes the sweep convergence reservoirs, such as the peripheral protuberances 713 having the general shape of sweep convergence reservoirs present in the refractory containers used to make the cutter. [0080] Additionally, and in a similar way as that described with respect to the embodiments in FIG. 6A and FIG. 7, an exemplary polycrystalline diamond cutter 650 formed using the assembly 420 of FIG. 4F includes (along an axis 670) a substrate 654, and a diamond body 652. In some embodiments, the second side 672 of the diamond body 652 includes a concave portion 680 extending radially inward from a peripheral region 674 adjacent to the edge side 676 toward the axis 670 of the cutter. In some embodiments, the concave portion 680 of the diamond body 652 has the general shape of the convex portion 422 of the inner bottom side of the refractory container 421 used to make the cutter (see FIG. 4F). The first side 678 of the diamond body 652 is attached to the substrate 654.

[0081] Additionally, the exemplary polycrystalline diamond cutter 650 formed using the assembly 420 of FIG. 4F can be further processed by machining along various surfaces,

Including planar, cylindrical, or hyperboloid surfaces. For example, and as shown In FIG.

6B and as represented by various dashed lines, the diamond cutter 650 with as-sintered diamond body 652 and substrate 654 formed using the assembly 420 in FIG. 4F can be machined to: i) reduce the height of the substrate by machining along plane 660; ii) reduce the overall diameter and/or circumference of the cutter by machining along cylinder 662; iii) reduce the height of the diamond body by machining along plane 664; and/or iv) add chamfered and/or beveled surfaces by machining along the frustum of cone 666. Such machining generally removes the mass of the diamond table 652 that includes the sweep convergence reservoirs, such as the peripheral protuberances 656 having the general shape of sweep convergence reservoirs present in the refractory containers used to make the cutter. [0082] However, in forming the diamond cutter 600, 650, finish machining (such as laser cutting, electrical discharge machining, grinding, lapping, and/or polishing) does not extend to the concave portion 603, 680. It should be noted that the reservoir regions and sides can be further finish machined as long as the concave portion 680 (or at least a portion of the concave portion, alternatively a majority portion of the area of the concave portion or at least 75% of the area of the concave portion) is not finish machined. For example and as shown in FIG. 68, the portion of the concave portion indicated by dashed line 682 can be the portion that is not finish machined. Such a portion may be, but is not necessarily, symmetric about axis 670.

[0083] Although not finish machined, any residual refractory cup from the HPHT process that remains in contact with or attached to the concave portion 603, 680 can be removed by acid leaching with, e.g., HCI or aqua regia, or by grit blasting with media such as SiC,

Add leaching and grit blasting of the concave portion 603, 680 does not affect the structure of the exposed sintered diamond partides on the surface of the concave portion

603, 680, and the exposed sintered diamond particles on such treated/blasted surfaces retain the physical structure of the as-sintered diamond particles, for example, the crystal facets of the as-sintered diamond partides. Through this processing, the exposed sintered diamond particles on at least a portion of the surface of the concave portion 603,

680 (alternatively a majority portion of the surface of the concave portion or at least 75% of the surface of the concave portion) retain the physical structure of the as-sintered diamond partide. In contrast, if the surface of the concave portion is finish machined as in conventional processing, e.g., with laser cutting, electrical discharge machining, grinding, lapping, and/or polishing, the surface of the concave portion is altered by the mechanical process of removal and the crystal facets of exposed, as-sintered diamond particles do not have the physical structure of the as-sintered diamond particles.

[0084] The beveled or chamfered surfaces described herein can have any size. In some embodiments, the beveled or chamfered surface may have a vertical height, i.e., length in the axial direction, of 0.5 mm to about 1 mm and an angle of 45 degrees which may provide a particularly strong and fracture resistant tool component. In some embodiments, the beveled or chamfered surface has a vertical height, i.e,, length in the axial direction, which is the same as the thickness, i.e., axial thickness, of the planar oriented portion.

[0085] In some embodiments, the diamond bodies described herein include a plurality of bonded diamond crystals and a plurality of interstitial regions. The composition of diamond bodies described herein includes sintered diamond particles sized between about 1 micron to about 50 microns, and a catalyst metal phase between about 8 percent by weight (wt.%) to about 25 percent by weight (wt.%). The diamond bodies are formed integrally to the substrate through a high pressure - high temperature sintering process as described herein during which catalyst diffuses into the diamond body and not only densities the diamond body, but also serves to mechanically bond the diamond body to the substrate.

[0086] In some embodiments, a portion of the interstitial regions include a catalyst material or catalyst material sintering residue. In some embodiments, a portion of the interstitial regions are substantially free of catalyst material or catalyst material sintering residue. In some embodiments, the portion of the diamond body including interstitial regions substantially free of catalyst material or catalyst material sintering residue, extends from the working surface into an interior volume of the diamond body. [0087] Any one or more of the features and structures in any one embodiment of the exemplary assemblies and the exemplary cutters described and disclosed herein can be selected and incorporated with any of the other features and structures in any one embodiment of the exemplary assemblies and the exemplary cutters described and disclosed herein to arrive at different combinations of such features and structures. In other words, the refractory cup, insert, substrate, diamond feed layer and type of concave portion (both of the refractory cup and of the resulting cutter) can be mixed and matched and intermingled from any of the several embodiments described and disclosed herein to form additional embodiments.

[0088] The exemplary cutters described and disclosed herein can be incorporated in drilling tools used, for example, in drilling geological formations. Such drilling tools can incorporate flushing media supplied to the drill head to facilitate removing debris from the drilling zone as well as to remove heat from the drill head that Is generated in the drilling operation. Examples of drilling tools include drag bits having polycrystalline diamond cutters arranged along a periphery region of a fin or blade.

[0089] While reference has been made to specific embodiments, it is apparent that other embodiments and variations can be devised by others skilled in the art without departing from their spirit and scope. The appended claims are intended to be construed to include all such embodiments and equivalent variations.