US20180142522A1

US20180142522A1 - Cutting elements having accelerated leaching rates and methods of making the same

Info

Publication number: US20180142522A1
Application number: US15/571,618
Authority: US
Inventors: Abhijit Suryavanshi; Andrew Gledhill; Christopher Long; Valeriy KONOVALOV; Kai Zhang
Original assignee: Diamond Innovations Inc
Current assignee: Diamond Innovations Inc
Priority date: 2015-05-08
Filing date: 2016-05-06
Publication date: 2018-05-24
Also published as: EP3294480A1; WO2016182864A1

Abstract

Cutting elements having accelerated leaching rates and methods of making the same are disclosed herein. In one embodiment, a method of forming a cutting element includes assembling a reaction cell having diamond particles, a non-catalyst material, a catalyst material, and a substrate within a refractory metal container, where the non-catalyst material is generally immiscible in the catalyst material at a sintering temperature and pressure. The method also includes subjecting the reaction cell and its contents to a high pressure high temperature sintering process to form a polycrystalline diamond body that is attached to the substrate. The method further includes contacting at least a portion of the polycrystalline diamond body with a leaching agent to remove catalyst material and non-catalyst material from the diamond body, where a leaching rate of the catalyst material and the non-catalyst material exceeds a conventional leaching rate profile by at least about 30%.

Description

TECHNICAL FIELD AND INDUSTRIAL APPLICABILITY

The present disclosure relates generally to cutting elements made from superhard abrasive materials and, more particularly, to cutting elements made from polycrystalline diamond having a non-catalyst material addition that accelerates leaching rates, and methods of making the same.

BACKGROUND

Polycrystalline diamond (“PCD”) compacts are used in a variety of mechanical applications, for example in material removal operations, as bearing surfaces, and in wire-draw operations. PCD compacts are often used in the petroleum industry in the removal of material in downhole drilling. The PCD compacts are formed as cutting elements, a number of which are attached to drill bits, for example, roller-cone drill bits and fixed-cutting element drill bits.
PCD cutting elements typically include a superabrasive diamond layer, referred to as a polycrystalline diamond body that is attached to a substrate. The polycrystalline diamond body may be formed in a high pressure high temperature (HPHT) process, in which diamond grains are held at pressures and temperatures at which the diamond particles bond to one another.
As is conventionally known, the diamond particles are introduced to the HPHT process in the presence of a catalyst material that, when subjected to the conditions of the HPHT process, promotes formation of inter-diamond bonds. The catalyst material may be introduced to the diamond particles in a variety of ways, for example, the catalyst material may be embedded in a support substrate such as a cemented tungsten carbide substrate having cobalt. The catalyst material may infiltrate the diamond particles from the support substrate. Following the HPHT process, the diamond particles may be sintered to one another and attached to the support substrate.
While the catalyst material promotes formation of the inter-diamond bonds during the HPHT process, the presence of the catalyst material in the sintered diamond body after the completion of the HPHT process may also reduce the stability of the polycrystalline diamond body at elevated temperatures. Some of the diamond grains may undergo a back-conversion to a softer non-diamond form of carbon (for example, graphite or amorphous carbon) at elevated temperatures. Further, mismatch of the coefficients of thermal expansion between diamond and the catalyst may induce stress into the diamond lattice causing microcracks in the diamond body. Back-conversion of diamond and stress induced by the mismatch of coefficients of thermal expansion may contribute to a decrease in the toughness, abrasion resistance, and/or thermal stability of the PCD cutting elements during operation.
It is conventionally known to at least partially remove catalyst material from the PCD by introducing at least a portion of the PCD to a leaching agent. However, the rate of the reaction to remove the catalyst material from the PCD may be slow, increasing the time of production of the PCD cutting elements and, therefore, the costs associated with manufacturing.
Accordingly, polycrystalline diamond cutting elements that have accelerated leaching of catalyst from the polycrystalline diamond body may be desired.

SUMMARY

In one embodiment, a method of forming a cutting element includes assembling a reaction cell having a plurality of diamond particles, a non-catalyst material, a catalyst material, and a substrate within a refractory metal container, where the non-catalyst material is generally immiscible in the catalyst material when both are held at the greater of the melting or liquidus temperature of the catalyst material or the non-catalyst material. The method also includes subjecting the reaction cell and its contents to a high pressure high temperature sintering process in which the catalyst material promotes formation of inter-diamond bonding between adjacent diamond particles to form a polycrystalline diamond body that is attached to the substrate. The method further includes contacting at least a portion of the polycrystalline diamond body with a leaching agent to remove catalyst material and non-catalyst material from the diamond body, where a leaching rate of the catalyst material and the non-catalyst material exceeds a conventional leaching rate profile by at least about 30%.
In another embodiment, a cutting element includes a substrate having a metal carbide and a catalyst material, and a polycrystalline diamond body bonded to the substrate. The polycrystalline diamond body includes a plurality of diamond grains that are bonded to adjacent diamond grains in diamond-to-diamond bonds and a plurality of interstitial regions positioned between adjacent diamond grains, where the plurality of interstitial regions include a non-catalyst material, the catalyst material, the metal carbide, or combinations thereof. A metal carbide concentration within the diamond body is less than about 70% of a conventional metal carbide concentration.
In yet another embodiment, a drill bit includes a bit body having a leading end structure for drilling a subterranean formation and a plurality of cutting elements mounted to the blades. At least one of the plurality of cutting elements includes a substrate having a metal carbide and a catalyst material and a polycrystalline diamond body bonded to the substrate. The polycrystalline diamond body having a plurality of diamond grains bonded to adjacent diamond grains in diamond-to-diamond bonds. The polycrystalline diamond body further includes a plurality of interstitial regions positioned between adjacent diamond grains, the plurality of interstitial regions having a non-catalyst material, catalyst material, metal carbide, or combinations thereof. A metal carbide concentration within the diamond body is less than about 70% of a conventional metal carbide concentration.
In yet another embodiment, a method of forming a cutting element includes assembling a reaction cell having a plurality of diamond particles, a non-catalyst material, a catalyst material, and a substrate within a refractory metal container, where the non-catalyst material is generally immiscible in the catalyst material when both are held at the greater of the melting or liquidus temperature of the catalyst material or the non-catalyst material. The method further includes subjecting the reaction cell and its contents to a high pressure high temperature sintering process in which the catalyst material promotes formation of inter-diamond bonding between adjacent diamond particles to form a polycrystalline diamond body that is attached to the substrate. The method also includes contacting at least a portion of the polycrystalline diamond body with a leaching agent to remove catalyst material and non-catalyst material from the diamond body, where the non-catalyst material has a higher rate of reaction with the leaching agent than the catalyst material.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the embodiments, will 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.

FIG. 1 is a schematic side cross-sectional view of a PCD cutting element according to one or more embodiments shown or described herein;

FIG. 2 is a detailed schematic side cross-sectional view of the PCD cutting element of FIG. 1A shown at location A;

FIG. 3 is a schematic flow chart depicting a manufacturing process of a PCD cutting element according to one or more embodiments shown or described herein;

FIG. 4 is a schematic flow chart depicting a manufacturing process of a PCD cutting element according to one or more embodiments shown or described herein;

FIG. 5 is a schematic perspective view of a drill bit having a plurality of PCD cutting elements according to one or more embodiments shown or described herein; and

FIG. 6 is a plot of data depicting weight loss of a PCD cutting element in a leaching process according to one or more embodiments shown or described herein.

DETAILED DESCRIPTION

The present disclosure is directed to polycrystalline diamond cutting elements, drill bits incorporating the same, and methods of making the same. A cutting element made according to the present disclosure may be formed by introducing a non-catalyst material and a catalyst material to a plurality of unbonded diamond particles. The non-catalyst material and the catalyst material may be generally immiscible with one another when both are held at the greater of the melting or liquidus temperature of the non-catalyst material or the catalyst material. The components are subjected to a high pressure high temperature sintering process in which the catalyst material promotes formation of inter-diamond bonding between adjacent diamond particles to form a polycrystalline diamond body. The polycrystalline diamond body is further contact with a leaching agent that removes catalyst material and non-catalyst material from the polycrystalline diamond body. The leaching rate of the catalyst material and the non-catalyst material exceeds a conventional leaching rate profile of a conventional cutting element made with equivalent diamond particle size, catalyst concentration, substrate chemistry, and sintering parameters by at least about 30%. Polycrystalline diamond cutting elements having accelerated leaching rates, rotary drill bits incorporating the same, and methods of making the same are described in greater detail below.
It is to be understood that this disclosure is not limited to the particular methodologies, systems and materials described, as these may vary. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope. For example, as used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. In addition, the word “comprising” as used herein is intended to mean “including but not limited to.” Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.
Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as size, weight, reaction conditions and so forth used in the specification and claims are to the understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the end user. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
As used herein, the term “about” means plus or minus 10% of the value of the number with which it is being used. Therefore, “about 40” means in the range of 36-44.
As used herein, the term “non-catalyst material” refers to an additive that is introduced to the polycrystalline diamond body, and that is not catalytic with carbon in forming diamond and inter-diamond grain bonds.
Polycrystalline diamond compacts (or “PCD compacts”, as used hereafter) may represent a volume of crystalline diamond grains with embedded foreign material filling the inter-granular spaces. In one example, a PCD compact includes a plurality of crystalline diamond grains that are bonded to each other by strong inter-diamond bonds and forming a rigid polycrystalline diamond body, and the inter-granular regions, disposed between the bonded grains and filled with a non-diamond material (e.g., a catalyst material such as cobalt or its alloys), which was used to promote diamond bonding during fabrication of the PCD compact. Suitable metal solvent catalysts may include the metal in Group VIII of the Periodic table. Polycrystalline diamond cutting elements (or “PCD cutting element”, as is used hereafter) include the above mentioned polycrystalline diamond body attached to a suitable support substrate (for example, cemented tungsten carbide-cobalt (WC—Co)). The attachment between the polycrystalline diamond body and the substrate may be made by virtue of the presence of a catalyst, for example cobalt metal. In another embodiment, the polycrystalline diamond body may be attached to the support substrate by brazing. In another embodiment, a PCD compact includes a plurality of crystalline diamond grains that are strongly bonded to each other by a hard amorphous carbon material, for example a-C or t-C carbon. In another embodiment, a PCD compact includes a plurality of crystalline diamond grains, which are not bonded to each other, but instead are bound together by foreign bonding materials such as borides, nitrides, or carbides, for example, bonded by SiC.
As used herein, “conventional cutting elements,” “conventional leaching rate profile,” “conventional metal carbide concentration,” and “conventional dispersive x-ray fluorescence spectrum” refer to cutting elements or properties of cutting elements made according to comparable processes to the newly-disclosed embodiments discussed herein. Such conventional cutting elements may serve as comparison to the newly-disclosed embodiments of the present disclosure to demonstrate modifications introduced by the newly disclosed embodiments. Such conventional cutting elements may exhibit equivalent diamond particle size distributions, HPHT processing parameters (for example, maximum temperature, time above sintering temperature, and maximum pressure), and substrate chemistry as comparable newly-disclosed embodiments.
As discussed above, conventional PCD cutting elements are used in a variety of industries and applications in material removal operations. PCD cutting elements are typically used in non-ferrous metal removal operations and in downhole drilling operations in the petroleum industry. Conventional PCD cutting elements exhibit high toughness, strength, and abrasion resistance because of the inter-granular inter-diamond bonding of the diamond grains that make up the polycrystalline diamond bodies of the PCD cutting elements. The inter-diamond bonding of the diamond grains of the polycrystalline diamond body are promoted during an HPHT process by a catalyst material. However, at elevated temperature, the catalyst material and its byproducts that remain present in the polycrystalline diamond body after the HPHT process may promote back-conversion of diamond to non-diamond carbon forms and may induce stress into the diamond lattice due to the mismatch in the coefficient of thermal expansion of the materials.
It is conventionally known to remove or deplete portions of the catalyst material to improve the thermal stability of the polycrystalline diamond body. The most common method of removing the catalyst material is a leaching process in which the PCD compact is introduced to a leaching agent, for example, an aqueous acid solution at elevated temperature. The leaching agent may be selected from a variety of conventionally-known compositions in which the catalyst material is known to dissolve. By dissolving and removing at least a portion of the catalyst material from the PCD compact, the abrasion resistance of the PCD compact may be increased due to the reduction in back-conversion rate of the diamond in the polycrystalline diamond body to non-diamond carbon forms and the reduction in materials having mismatched coefficients of thermal expansion. However, a portion of catalyst material may still remain in the diamond body of the PCD compact that have been subjected to the leaching process. The interstitial regions between diamond grains may form “trapped” or “entrained” volumes into which the leaching agent has limited or no accessibility. Therefore, these trapped volumes remain populated with the constituents of the PCD formation process. The trapped volumes that contain catalyst material contribute to the degradation of the abrasion resistance of the PCD cutting element at elevated temperature that is generated during use of the PCD cutting element to remove material. Thus, reduction of trapped catalyst material may improve the abrasion resistance of PCD compact cutting elements.
The present disclosure is directed to polycrystalline diamond cutting elements that incorporate a non-catalyst material that is distributed throughout the polycrystalline diamond body. The non-catalyst material may be selected from a variety of materials, including metals, metal alloys, metalloids, metal-organic composites, semiconductors, low melting temperature metal oxides, glass, and combinations thereof. In particular examples, the non-catalyst material may be lead or bismuth. The non-catalyst material may be introduced to the diamond particles prior to or concurrently with the HPHT process. The non-catalyst material may be distributed throughout the polycrystalline diamond body evenly or unevenly, as well as by forming a distribution pattern. The non-catalyst material may reduce the amount of catalyst material that is present in the polycrystalline diamond body following the HPHT process. Further, the non-catalyst material may reduce the amount of catalyst material that is present in the polycrystalline diamond body following a catalyst depletion process or leaching process in which both the non-catalyst material and the catalyst material are removed from the portions of the polycrystalline diamond body or from the entire polycrystalline diamond body. Additionally, the non-catalyst material may increase the removal rate (or the “leaching rate”) of the catalyst material from the polycrystalline diamond body.
Because of the reduction of the catalyst material in the polycrystalline diamond body, polycrystalline diamond cutting elements according to the present disclosure exhibit performance that exceeds that of conventional PCD cutting elements in at least one of toughness, strength, and abrasion resistance.
Referring now to FIGS. 1 and 2, a PCD cutting element 100 is depicted. The PCD cutting element 100 includes a support substrate 110 and a polycrystalline diamond body 120 that is attached to the support substrate 110. The polycrystalline diamond body 120 includes a plurality of diamond grains 122 that are bonded to one another, including being bonded to one another through inter-diamond bonding. The bonded diamond grains 122 form a diamond lattice that extends along the polycrystalline diamond body 120. The diamond body 120 also includes a plurality of interstitial regions 124 between the diamond grains. The interstitial regions 124 represent a space between the diamond grains. In at least some of the interstitial regions 124, a non-carbon material is present. In some of the interstitial regions 124, a non-catalyst material is present. In other interstitial regions 124, catalyst material is present. In yet other interstitial regions 124, both non-catalyst material and catalyst material are present. In yet other interstitial regions 124, at least one of catalyst material, non-catalyst material, swept material of the support substrate 110, for example, cemented tungsten carbide, and reaction by-products of the HPHT process are present. Non-carbon, non-catalyst or catalyst materials may be bonded to diamond grains. Alternatively, non-carbon, non-catalyst or catalyst materials may be not bonded to diamond grains.
The catalyst material may be a metallic catalyst, including metallic catalysts selected from Group VIII of the periodic table, for example, cobalt, nickel, iron, or alloys thereof. The catalyst material may be present in a greater concentration in the support substrate 110 than in the polycrystalline diamond body 120, and may promote attachment of the support substrate 110 to the polycrystalline diamond body 120 in the HPHT process, as will be discussed below. The polycrystalline diamond body 120 may include an attachment region 128 that is rich in catalyst material promotes bonding between the polycrystalline diamond body 120 and the support substrate 110. In other embodiments, the concentration of the catalyst material may be greater in the polycrystalline diamond body 120 than in the support substrate 110. In yet other embodiments, the catalyst material may differ from the catalyst of the support substrate 110. The catalyst material may be a metallic catalyst reaction-byproduct, for example catalyst-carbon, catalyst-tungsten, catalyst-chromium, or other catalyst compounds, which also may have lower catalytic activity towards diamond than a metallic catalyst.
The non-catalyst material may be selected from a variety of materials that are non-catalyst with the carbon-diamond conversion and include, for example, metals, metal alloys, metalloids, semiconductors, and combinations thereof. The non-catalyst material may be selected from one of copper, silver, gold, aluminum, silicon, gallium, lead, tin, bismuth, indium, thallium, tellurium, antimony, polonium, lithium, magnesium, and alloys thereof. Following the HPHT process, the non-catalyst material may be present in elemental or alloyed form, or in carbides, nitrides, or carbonitrides thereof. In some embodiments, the non-catalyst material may be generally immiscible with the catalyst material when both are liquid such that the non-catalyst material and the catalyst material do not significantly alloy with one another when both are liquid. In some embodiments, the non-catalyst material may have a lower liquidus or melting temperature than the liquidus or melting temperature of the catalyst material.
Both non-catalyst material and catalyst material may be present in a detectable amount in the polycrystalline diamond body of the PCD cutting element both before and after subjecting the polycrystalline diamond body to leaching. Presence of such materials may be identified by X-ray fluorescence, for example using a XRF analyzer available from Bruker AXS, Inc. of Madison, Wis., USA. Presence of such material may also be identified using X-ray diffraction, energy dispersive spectroscopy, or other suitable techniques.
The non-catalyst material may be introduced to the unbonded diamond particles prior to the HPHT process that bonds the diamonds particles in an amount that is in a range from about 0.1 vol. % to about 5 vol. % of the diamond body 120, for example an amount that is in a range from about 0.2 vol. % to about 4 vol. % of the diamond body 120, for example an amount that is in a range from about 0.5 vol. % to about 3 vol. %. In an exemplary embodiment, non-catalyst material may be introduced to the unbonded diamond in an amount from about 0.33 to about 1.5 vol. %. Following this HPHT process and leaching, the non-catalyst material content in the leached region of the diamond body 120 is reduced by at least about 50%, including being reduced in a range from about 50% to about 80%.
In the HPHT process that bonds the diamond particles, catalyst material may be introduced to the diamond powders. The catalyst material may be present in an amount that is in a range from about 0.1 vol. % to about 30 vol. % of the diamond body 120, for example an amount that is in a range from about 0.3 vol. % to about 10 vol. % of the diamond body 120, including being an amount of about 5 vol. % of the diamond body 120. In an exemplary embodiment, catalyst material may be introduced to the unbonded diamond is an amount from about 4.5 vol. % to about 6 vol. %. Following this HPHT process and leaching, the catalyst material content in the leached region of the diamond body 120 is reduced by at least about 50%, including being reduced in a range from about 50% to about 90%.
The non-catalyst material and the catalyst material may be non-uniformly distributed in the bulk of the polycrystalline diamond cutting element 100 such that the respective concentrations of non-catalyst material and catalyst material vary at different positions within the polycrystalline diamond body 120. In one embodiment the non-catalyst material may be arranged to have a concentration gradient that is evaluated along a longitudinal axis 102 of the polycrystalline diamond cutting element 100. The concentration of the non-catalyst material may be higher at positions evaluated distally from the substrate 110 than at positions evaluated proximally to the substrate 110. In opposite, the concentration of the catalyst material may be greater at positions evaluated proximally to the substrate 110 that at positions evaluated distally from the substrate 110. In yet another embodiment, the concentrations of the non-catalyst material and the catalyst material may undergo a step change when evaluated in a longitudinal axis 192 of the polycrystalline diamond cutting element 100. In yet another embodiment, the concentrations of the non-catalyst material and the catalyst material may exhibit a variety of patterns or configurations. Independent of the concentration of the non-catalyst material and the catalyst material in the polycrystalline diamond body 120, however, both non-catalyst material and catalyst material may be detectible along surfaces proximately and distally located relative to the substrate 110.
The concentration gradient of the non-catalyst material and the catalyst material may affect the overall leaching rate of the polycrystalline diamond body 120, because the catalyst material and the non-catalyst material may have different rates of reaction with the leaching agent. For example, the non-catalyst material may exhibit a faster rate of reaction with the leaching agent than the catalyst material. The regions of the polycrystalline diamond body 120 that have higher concentrations of non-catalyst material relative to catalyst material may exhibit increased leaching rates than regions of the polycrystalline diamond body 120 that have lower concentrations of non-catalyst material relative to catalyst material. Therefore, regions having relatively high concentrations of non-catalyst material may exhibit particularly fast leaching rates. The leaching rate may decrease as the leaching agent comes into contact with material in the interstitial regions of the polycrystalline diamond body 120 having higher concentrations of catalyst material.
The gradient of concentration of catalyst material and non-catalyst material may further affect the pattern of leaching within the polycrystalline diamond body 120, for example the pattern of leaching when evaluated along the outer diameter of the cutting element 100 when the concentration gradient of non-catalyst material and catalyst material is arranged along the longitudinal axis of the cutting element 100. In such cutting elements 100 that are subjected to the leaching process, leaching agent may remove material from the interstitial regions to a greater depth at axial positions of higher non-catalyst concentration and material to a smaller depth at axial positions of lower non-catalyst concentration. Therefore, cutting elements 100 may exhibit variation in the interface region between leached regions and unleached regions for cutting elements 100 that are less than fully leached.
In another embodiment, the polycrystalline diamond body 120 may exhibit relatively high amounts of the catalyst material at positions proximate to the substrate 110 and at which the catalyst material forms a bond between the polycrystalline diamond body 120 and the substrate 110. In some embodiments, at positions outside of such an attachment zone, the non-catalyst material and the catalyst material maintain the concentration variation described above.
PCD cutting elements 100 according to the present disclosure may exhibit improved performance as compared to conventionally produced PCD cutting elements when evaluated in terms of abrasion resistance and/or toughness. The performance of PCD cutting elements 100 according to the present disclosure may particularly exhibit improved performance when subjected to conditions of elevated temperature. Such conditions may occur when the PCD cutting elements 100 are used in aggressive material removal operations, for example, aggressive downhole drilling operations in the petroleum industry. Performance of the PCD cutting element 100 with respect to abrasion resistance may be quantified in laboratory testing, for example using a simulated cutting operation in which the PCD cutting element 100 is used to machine an analogous material that replicates an end user application.
In one example used to replicate a downhole drilling application, the PCD cutting element 100 is held in a vertical turret lathe (“VTL”) to machine granite. Parameters of the VTL test may be varied to replicate desired test conditions. In one example, the cutting element that is subjected to the VTL test is water cooled. In one example, the PCD cutting element 100 was positioned to maintain a depth of cut of about 0.017 in/pass at a cross-feed rate of about 0.17 in/revolution and a cutting element velocity of 122 surface feet per minute. The VTL test introduces a wear scar into the PCD cutting element 100 along the position of contact between the PCD cutting element 100 and the granite. The size of the wear scar is compared to the material removed from the granite to evaluate the abrasion resistance of the PCD cutting element 100. The life of the PCD cutting element 100 may be calculated based on the material removed from the granite as compared to the size of the wear scar abrades through the polycrystalline diamond body 120 and into the support substrate 110.
In another example, the PCD cutting element 100 is subjected to a dry interrupted milling test that implements a fly cutting tool holder and workpiece arrangement in which the PCD cutting element 100 is periodically removes material from a workpiece and then is brought out of contact with the workpiece. The interrupted milling test is described in U.S. patent application Ser. No. 13/791,277, the entire disclosure of which is hereby incorporated by reference. The interrupted milling test may evaluate thermal resistance of the PCD cutting element 100.
In some embodiments, PCD cutting elements 100 according to the present disclosure exhibit increased abrasion resistance as compared to conventionally produced PCD cutting elements. In some embodiments, PCD cutting elements 100 according to the present disclosure may exhibit at least about 30% less wear with an equivalent amount of material removed from the granite as compared to conventionally produced PCD cutting elements, including exhibiting about 78% less wear than a conventional cutting element, including exhibiting about 90% less wear than a conventional cutting element. In some embodiments, the PCD cutting elements 100 according to the present disclosure may exhibit at least about 30% more material removal from the workpiece as evaluated at the end of life of the PCD cutting element as compared to a conventional PCD cutting element.
PCD cutting elements 100 according to the present disclosure exhibit a lower concentration of trapped catalyst material in interstitial regions between the bonded diamond grains as compared to conventionally processed cutting elements. As discussed above, because the trapped catalyst material that is positioned within the interstitial regions may contribute to back-conversion of the diamond grains to non-diamond forms of carbon. The propensity of the polycrystalline diamond body 120 of the PCD cutting element 100 to back-convert to non-diamond forms of carbon may be correlated to the high-temperature abrasion resistance of the PCD cutting element 100. Reducing the amount of the trapped catalyst material within the interstitial regions between diamond grains of the polycrystalline diamond body 120 may reduce the rate of back-conversion of the PCD cutting element 100. Further, reducing the amount of trapped catalyst material within the interstitial regions between diamond grains of the polycrystalline diamond body 120 may reduce stress that is induced into the diamond lattice caused by a mismatch in the thermal expansion and the modulus of the diamond grains and the catalyst material. Therefore, the reduction in the trapped catalyst material within the interstitial regions between the diamond grains resulting from the introduction of non-catalyst material into the polycrystalline diamond body 120, improves performance of the PCD cutting element 100 as compared to conventionally produced PCD cutting elements.
Still referring to FIG. 1, some embodiments of the PCD cutting element 100 include a crown portion 402 that is positioned within the polycrystalline diamond body 120 and along a surface opposite the substrate 110. The crown portion 402 is made from a material that is dissimilar from the material of the polycrystalline diamond body 120 and the support substrate 110. The crown portion 402 may extend into the diamond body 120 from the top surface of the PCD cutting element 100. The crown portion 402 may extend to a depth that is less than about 1 mm from the support substrate 110 including being about 300 μm from the support substrate 110. The crown portion 402 may limit the depth that the catalyst material 94 sweeps into the polycrystalline diamond body 120 from the second support substrate 110 during the second HPHT process. The crown portion 402 may provide locally modified material properties of the PCD cutting element 100. In one embodiment, the crown portion 402 may include, in addition to the bonded diamond grains, a carbide forming material such as, for example and without limitation, aluminum, silicon, titanium, and alloys, carbides, nitrides, or carbonitrides thereof. In one embodiment, the crown portion 402 may include, in addition to the bonded diamond grains, non-catalyst material in detectable amounts. Examples of such non-catalyst materials include, for example and without limitation, copper, silver, gold, aluminum, silicon, gallium, lead, tin, bismuth, indium, thallium, tellurium, antimony, polonium, lithium, magnesium and alloys, nitrides, carbides, or carbonitides thereof.
In some embodiments, the polycrystalline diamond body 120 may be free of such materials outside of the attachment region 128.
PDC cutting elements according to the present disclosure may be fabricated using so-called “single press” or “double press” HPHT process. In a single press HPHT process, diamond particles may be subjected to a high pressure high temperature sintering process in which diamond particles are subjected to elevated pressure to form an unbounded diamond volume having a plurality of diamond particles that contact one another and a plurality of interstitial regions positioned between adjacent diamond particles. Non-catalyst material is melted and pooled in interstitial regions. In some embodiments, the non-catalyst material may be mixed with the diamond particles prior to initiation of the HPHT process. In other embodiments, the non-catalyst material may be swept into the interstitial regions between the diamond particles during the HPHT process from an external source. In yet other embodiments, the non-catalyst material may be both mixed with the diamond particles prior to initiation of the HPHT process and swept into the interstitial regions between the diamond particles during the HPHT process from an external source.
Subsequent to melting of the non-catalyst material, the catalyst material may be melted. The non-catalyst material and the catalyst material may be selected such that the melting or liquidus temperature of the non-catalyst material is lower than the melting or liquidus temperature of the catalyst material. In some embodiments, the melting or liquidus temperature of the non-catalyst material may be lower than the solidus temperature of the catalyst material. In some embodiments, the catalyst material may be mixed with the diamond particles prior to initiation of the HPHT process. In other embodiments, the catalyst material may be swept into the interstitial regions between the diamond particles during the HPHT process from an external source, for example a substrate having a metal carbide composition that includes catalyst material. In yet other embodiments, the catalyst material may be both mixed with the diamond particles prior to initiation of the HPHT process and swept into the interstitial regions between the diamond particles during the HPHT process from an external source.
With the catalyst material molten in a liquid state, the catalyst may dissolve at least a portion of the carbon from the diamond particles. As is conventionally known, the molten catalyst material may act as a solvent catalyst that diamond may re-precipitate from, such that the diamond particles form diamond-to-diamond bonds between one another, thereby forming a polycrystalline diamond body. The polycrystalline diamond body includes a plurality of diamond grains that are coupled to one another through diamond-to-diamond bonds, and having a plurality of interstitial regions positioned therebetween. A significant portion of the interstitial regions between the diamond grains are connected to one another such that the interstitial regions form an interconnected network of interstitial regions. The interconnected network of interstitial regions can be penetrated by a leaching agent during the process of catalyst removal from the polycrystalline diamond body, as will be discussed in greater detail below. However, some of the interstitial regions within the polycrystalline diamond body may be “trapped” such that they are separated from the interconnected network of interstitial regions and therefore cannot be penetrated by the leaching region. The interstitial regions between the diamond grains may be filled with non-catalyst material, catalyst material, metal carbide, or combinations thereof. The polycrystalline diamond body may be attached to a substrate.
As conventionally known, the diamond body may be contacted with a leaching agent that removes at least a portion of the materials present in the interstitial regions that are positioned proximate to the location of leaching agent application. For example, the polycrystalline diamond body may be submerged in a leaching agent such that surfaces of the polycrystalline diamond body contact the leaching agent, while surfaces of the substrate, to which the polycrystalline diamond body are attached, are maintained spaced apart from contact with the leaching agent. The leaching agent may be selected to attack the non-catalyst material and the catalyst material while preserving the diamond grains.
The non-catalyst material and the catalyst material may undergo chemical reaction with the leaching agent. The non-catalyst material may be more reactive with the leaching agent than the catalyst material such that the rate of reaction is higher for the non-catalyst material than for the catalyst material, and such that the rate of material removal by leaching is higher for diamond bodies formed with non-catalyst material and catalyst material as compared to diamond bodies formed without the introduction of non-catalyst material.
In one embodiment, the combined leaching of the catalyst material and the non-catalyst material may exceed a conventional leaching rate by at least about 30%. A conventional leaching rate is discussed in further detail below. In another embodiment, the combined leaching rate of the catalyst material and the non-catalyst material may exceed the convention leaching rate by at least about 40%. In yet another embodiment, the combined leaching rate of the catalyst material and the non-catalyst material may exceed the convention leaching rate profile by up to about 60%. In one embodiment, a leached depth of 800 μm from the working surface of the polycrystalline diamond body is achieved in less than about 7 days of exposure to the leaching agent. In comparison, a leached depth of 800 μm from the working surface of a polycrystalline diamond body according to the conventional leaching rate is achieved in about 10 days of exposure to the leaching agent.
The incorporation of non-catalyst material into the diamond body during the HPHT process may result in a decrease in the total catalyst content both prior to and following leaching as compared to conventional cutting elements that do not include non-catalytic material. The decrease in catalyst content as compared to conventional cutting elements may increase cutting element life by decreasing internal mechanical stresses attributable to mismatch between the coefficients of thermal expansion and modulus of the diamond grains, the non-catalytic material, and the catalytic material, and any back-conversion to non-diamond forms of carbon, which may be accelerated due to the presence of catalyst material. Further, the increase in leaching rate may reduce manufacturing time associated with producing a cutting element according to embodiments disclosed herein, in particular, by reducing the cycle time associated with leaching the non-catalytic material and catalytic material from the interstitial regions of the diamond body.
Additionally, the incorporation of non-catalyst material into the diamond body during the HPHT process may result in a decrease in the metal carbide concentration in the diamond body as compared to conventional diamond bodies made without the introduction of non-catalyst materials. Metal carbides are typically introduced to the diamond bodies during the HPHT process from the substrate, which, in one example, may be made from a cemented tungsten carbide. In one embodiment, the metal carbide concentration within diamond bodies according to the present disclosure may be less than 70% of the metal carbide concentration of a conventional diamond body, for example being less than about 50% of the metal carbide concentration of a conventional diamond body, for example being less than about 30% of the metal carbide concentration of a conventional diamond body.
In one manufacturing process, cutting elements may be produced in a “single press” HPHT process in which diamond particles are bonded to one another and a substrate to form a cutting element having an integral diamond body with diamond grains bonded to one another in diamond-to-diamond bonds and interstitial regions between the diamond grains. Some of the interstitial regions include non-catalyst material, catalyst material, metal carbide, or combinations thereof. Portions of the diamond body are maintained in contact with a leaching agent that removes substantially all of the non-catalyst material and catalyst material from a leached region positioned at the working surface of the cutting element and extending toward the substrate to a transition zone in which the leached region abuts the unleached region that is rich with non-catalyst material and catalyst material.
Referring now to FIG. 3, a flowchart depicting a manufacturing procedure 400 is provided. Diamond particles 90 are mixed with the non-catalyst material 92 in step 402. The size of the diamond particles 90 may be selected based on the desired mechanical properties of the polycrystalline diamond cutting element that is finally produced. It is generally believed that a decrease in grain size increases the abrasion resistance of the polycrystalline diamond cutting element, but decreases the toughness of the polycrystalline diamond cutting element. Further, it is generally believed that a decrease in grain size results in an increase in interstitial volume of the PCD compact. In one embodiment, the diamond particles 90 may have a single mode median volumetric particle size distribution (D50) in a range from about 10 μm to about 100 μm, for example having a D50 in a range from about 14 μm to about 50 μm, for example having a D50 of about 30 μm to about 32 μm. In other embodiments, the diamond particles 90 may have a D50 of about 14 μm, or about 17 μm, or about 30 μm, or about 32 μm. In other embodiments, the diamond particles 90 may have a multimodal particle size, wherein the diamond particles 90 are selected from two or more single mode populations having different values of D50, including multimodal distributions having two, three, or four different values of D50.
The non-catalyst material 92 may be introduced to step 402 as a powder. In other embodiments, the non-catalyst material 92 may be coated onto the unbonded diamond particles. The particle size of the non-catalyst material may be in a range from about 0.005 μm to about 100 μm, for example being in a range from about 10 μm to about 50 μm. The non-catalyst material 92 may be coated onto the unbounded diamond particles by conventionally-known coating techniques, including, for example, chemical vapor deposition, physical vapor deposition, thin film deposition, electrochemical plating, electroless plating, thermal spraying, and the like.
The diamond particles 90 and the non-catalyst material 92 may be dry mixed with one another using, for example, a commercial TURBULA® Shaker-Mixer available from Glen Mills, Inc. of Clifton, N.J. or an acoustic mixer available from Resodyn Acoustic Mixers, Inc. of Butte, Mont. to provide a generally uniform and well mixed combination. In other embodiments, the mixing particles may be placed inside a bag or container and held under vacuum or in a protective gas atmosphere during the blending process.
In other embodiments, the non-catalyst material 92 may be positioned separately from the diamond particles 90. During the first HPHT process, the non-catalyst materials 92 may “sweep” from their original location and through the diamond particles 90, thereby positioning the non-catalyst materials 92 prior to sintering of the diamond particles 90. Subsequent to sweeping of the non-catalyst materials 92, the catalyst material 94 may be swept through the diamond particles 90 during the first HPHT process, thereby promoting formation of inter-diamond bonds between the diamond particles 90 and sintering of the diamond particles 90 to form the polycrystalline diamond body 120 of the polycrystalline diamond compact 80.
The diamond particles 90 and the non-catalyst material 92 may be positioned within a cup 142 that is made of a refractory material, for example tantalum, niobium, vanadium, molybdenum, tungsten, or zirconium, as shown in step 404. The support substrate 144 is positioned along an open end of the cup 142 and is optionally welded to the cup 142 to form cell assembly 140 that encloses diamond particles 90 and the non-catalyst material 92. The support substrate 144 may be selected from a variety of hard phase materials including, for example, cemented tungsten carbide, cemented tantalum carbide, or cemented titanium carbide. In one embodiment, the support substrate 144 may include cemented tungsten carbide having free carbons, as described in U.S. Provisional Application Nos. 62/055,673, 62/055,677, and 62/055,679, the entire disclosures of which are hereby incorporated by reference. The support substrate 144 may include a pre-determined quantity of catalyst material 94. Using a cemented tungsten carbide-cobalt system as an example, the cobalt is the catalyst material 94 that is infiltrated into the diamond particles 90 during the HPHT process. In other embodiments, the cell assembly 140 may include additional catalyst material (not shown) that is positioned between the support substrate 144 and the diamond particles 90. In further other embodiments, the cell assembly 140 may include non-catalyst material 92 that is positioned between the diamond particles 90 and the support substrate 144 or between the diamond particles 90 and the additional catalyst material (not shown).
The cell assembly 140, which includes the diamond particles 90, the non-catalyst material 92, and the support substrate 144, is introduced to a press that is capable of and adapted to introduce ultra-high pressures and elevated temperatures to the cell assembly 140 in an HPHT process, as shown in step 408. The press type may be a belt press, a cubic press, or other suitable presses. The pressures and temperatures of the HPHT process that are introduced to the cell assembly 140 are transferred to contents of the cell assembly 140. In particular, the HPHT process introduces pressure and temperature conditions to the diamond particles 90 at which diamond is stable and inter-diamond bonds form. The temperature of the HPHT process may be at least about 1000° C. (e.g., about 1200° C. to about 1800° C., or about 1300° C. to about 1600° C.) and the pressure of the HPHT process may be at least 4.0 GPa (e.g., about 4.0 GPa to about 12.0 GPa, or about 5.0 GPa to about 10 GPa, or about 5.0 GPa to about 8.0 GPa) for a time sufficient for adjacent diamond particles 90 to bond to one another, thereby forming an integral PCD compact having the polycrystalline diamond body 120 and the support substrate 144 that are bonded to one another.
The introduction of the non-catalyst material 92 to the polycrystalline diamond body 120 prior to the HPHT process may result in a reduction of catalyst material 94 that is present in the polycrystalline diamond body 120 following the HPHT process and prior to initiation of any subsequent leaching process. As compared to conventional cutting elements that are produced without the introduction of the non-catalyst material 92, unleached diamond bodies 120 produced according to the present disclosure may contain, for example, about 10% less catalyst material 94 when evaluated prior to leaching.
The polycrystalline diamond body 120 may undergo a leaching process in which the catalyst material is removed from the polycrystalline diamond body 120. In one example of a leaching process, the polycrystalline diamond body 120 is introduced to a leaching agent of an acid bath to remove the remaining support substrate 144 from the polycrystalline diamond body 120, as shown in step 412. The leaching process may also remove non-catalyst material 92 and catalyst material 94 from the polycrystalline diamond body 120 that is accessible to the acid. Suitable acids may be selected based on the solubility of the non-catalyst material 92 and the catalyst material 94 that is present in the polycrystalline diamond body. Examples of such acids include, for example and without limitation, ferric chloride, cupric chloride, nitric acid, hydrochloric acid, hydrofluoric acid, aqua regia, or solutions or mixtures thereof. The acid bath may be maintained at an pre-selected temperature to modify the rate of removal of the non-catalyst material 92 and the catalyst material 94 from the polycrystalline diamond body 120, including being in a temperature range from about 10° C. to about the boiling point of the leaching agent. In some embodiments, the acid bath may be maintained at elevated pressures that increase the liquid boiling temperature and thus allow the use of elevated temperatures, for example being at a temperature of greater than the boiling point of the leaching agent. The polycrystalline diamond body 120 may be subjected to the leaching process for a time sufficient to remove the desired quantity of non-catalyst material 92 and catalyst material 94 from the polycrystalline diamond body. The polycrystalline diamond body 120 may be subjected to the leaching process for a time that ranges from about one hour to about one month, including ranging from about one day to about 7 days.
In some embodiments, the polycrystalline diamond body 120 may be maintained in the leaching process until the polycrystalline diamond body 120 is at least partially leached. In polycrystalline diamond bodies 120 that are partially leached, the exterior regions of the polycrystalline diamond bodies 120 that are positioned along the outer surfaces of the polycrystalline diamond bodies 120 have the accessible interstitial regions depleted of non-catalyst material 92 and/or catalyst material 94, while the interior regions of the polycrystalline diamond bodies 120 are rich with non-catalyst material 92 and/or catalyst material 94. In such partially leached polycrystalline diamond bodies 120, all of the accessible interstitial regions between the diamond grains may be fully depleted of non-catalyst material 92 and/or catalyst material 94. In some embodiments, metal carbide that is introduced to the polycrystalline diamond body 120 during the HPHT process may remain in the accessible interstitial regions.
In some embodiments, the extent of the leaching may be monitored by weighing the polycrystalline diamond body 120 after a pre-defined period of time. As the change in the weight loss of the polycrystalline diamond body 120 approaches a threshold value (for example, about 10.5% loss of the unleached polycrystalline diamond body 120), the polycrystalline diamond body 120 may be considered to be completely leached. The weight loss threshold value may vary with the type of PCD body depend on, for example, the diamond grain size, type and amount of added non-catalyst material, and the like. Because the polycrystalline diamond body 120 is leached without the support substrate 144, the leach fronts may extend from opposing sides of the polycrystalline diamond body 120 and from the perimeter surface of the polycrystalline diamond body 120. When the leach fronts from the opposing sides of the polycrystalline diamond body 120 meet, the polycrystalline diamond body 120 may be considered to be completely leached. In some embodiments, the extent of leaching may be monitored by the loss of density of the diamond body.
In some embodiments, an unleached polycrystalline diamond body may have non-catalyst material 92 and catalyst material 94 at greater than about 4 vol. % of the polycrystalline diamond body 120, including being from about 4 vol. % to about 15 vol. %. In comparison, a completely leached portion of a polycrystalline diamond body 120 may have non-catalyst material 92 and catalyst material 94 that is less than about 50% less than the unleached polycrystalline diamond body 120, for example at about 42 vol. % less than the polycrystalline diamond body 120. A completely leached polycrystalline diamond body 120 may have non-catalyst material 92 and catalyst material 94 being from about 0.25 vol. % to about 6 vol. %, for example, being from about 0.2 vol. % to about 1 vol. %. In general, the extent of loss of non-catalyst material and catalyst material in a completely leached polycrystalline diamond body 120 is determined the material structure and composition, for example by the precursor diamond grain size and the particle size distribution.
As discussed above, the introduction of the non-catalyst material to the polycrystalline diamond body 120 reduces the concentration of the catalyst material 94 in the polycrystalline diamond body 120 prior to leaching. The introduction of the non-catalyst material 92 to the polycrystalline diamond body 120 also reduces the concentration of the trapped catalyst material 94 that remains present in the trapped interstitial volumes of the polycrystalline diamond body 120 following complete leaching of the polycrystalline diamond body 120. As compared to conventional cutting elements that are produced without the introduction of the non-catalyst material 92, diamond bodies 120 produced according to the present disclosure contain from about 30 vol. % to about 90 vol. % less catalyst material 94 following complete leaching of both of the compared diamond bodies.
The introduction of the non-catalyst material 92 to the polycrystalline diamond body 120 may also increase the leaching rate of the polycrystalline diamond body 120, such that the duration of time required to obtain complete leaching of the polycrystalline diamond body 120 is reduced as compared to conventionally produced diamond bodies. For example, complete leaching of the polycrystalline diamond body 120 having non-catalyst material 92 according to the present disclosure may be obtained from about 30% to about 60% less time as compared to conventional cutting elements that are produced without the introduction of the non-catalyst material 92. In one example, when evaluated after 7 days of introduction to the leaching process, polycrystalline diamond bodies 120 produced according to the present disclosure exhibited from about 40% to about 70% more mass loss than conventional PCD compacts.
Following complete leaching of the polycrystalline diamond body 120, the polycrystalline diamond body 120 continues to exhibit non-diamond components that are present in the trapped interstitial regions of the polycrystalline diamond body 120 that are positioned between bonded diamond grains in at least detectable amounts. However, the reduction of the non-diamond components (including catalyst material 94) in the leaching process accessible interstitial regions reduces the content of catalyst material 94 in the polycrystalline diamond body 120 and increases the thermal stability of the polycrystalline diamond body 120.
Following formation of the integral PCD compact 82, the PCD compact 82 may be processed through a variety of finishing operations to remove excess material from the PCD compact 82 and configure the PCD compact 82 for use by an end user, including formation of a cutting element 84, as shown in step 418. Such finishing operations may include, for example, grinding and polishing the outside diameter of the PCD compact 82, cutting, grinding, lapping, and polishing the opposing faces (both the support-substrate-side face and the diamond-body-side face) of the PCD compact 82, and grinding and lapping a chamfer into the PCD compact 82 between the diamond-body-side face and the outer diameter of the PCD compact 82.
In an alternative manufacturing process, cutting elements may be produced in a “double press” HPHT process in which diamond particles are bonded to one another to form the diamond body in a first HPHT process, the diamond body is fully leached of non-catalyst material and catalyst material from the accessible interstitial volumes between the diamond grains, and the diamond body is attached to a substrate in a second HPHT process. The diamond particles may first be subjected to a first HPHT process to form a polycrystalline diamond compact having a polycrystalline diamond body that is formed through sintering with a catalyst material source. In one embodiment, the catalyst material source is provided integrally with a support substrate (a first support substrate). Substantially all of the support substrate is removed from the polycrystalline diamond body, the polycrystalline diamond body is machined to a desired shape, and the polycrystalline diamond body is leached to remove substantially all of the accessible non-catalyst material and catalyst material from the interstitial spaces of the polycrystalline diamond body. The leached polycrystalline diamond body is subsequently cleaned of leaching debris and bonded to a support substrate in a second HPHT process, thus forming a PCD compact. This PCD compact is subsequently finished according to conventionally known procedures to the final shape desirable for the end user application.
Referring now to FIG. 4, a flowchart depicting a manufacturing procedure 200 is provided. Diamond particles 90 are mixed with the non-catalyst material 92 in step 202. The size of the diamond particles 90 may be selected based on the desired mechanical properties of the polycrystalline diamond cutting element that is finally produced. It is generally believed that a decrease in grain size increases the abrasion resistance of the polycrystalline diamond cutting element, but decreases the toughness of the polycrystalline diamond cutting element. Further, it is generally believed that a decrease in grain size results in an increase in interstitial volume of the PCD compact. The porosity represents the total accessible interstitial space of the polycrystalline diamond body. In one embodiment, the diamond particles 90 may have a single mode median volumetric particle size distribution (D50) in a range from about 10 μm to about 100 μm, for example having a D50 in a range from about 14 μm to about 50 μm, for example having a D50 of about 30 μm to about 32 μm. In other embodiments, the diamond particles 90 may have a D50 of about 14 μm, or about 17 μm, or about 30 μm, or about 32 μm. In other embodiments, the diamond particles 90 may have a multimodal particle size, wherein the diamond particles 90 are selected from two or more single mode populations having different values of D50, including multimodal distributions having two, three, or four different values of D50.
The non-catalyst material 92 may be introduced to step 202 as a powder. In other embodiments, the non-catalyst material 92 may be coated onto the unbonded diamond particles. The particle size of the non-catalyst material may be in a range from about 0.005 μm to about 100 μm, for example being in a range from about 10 μm to about 50 μm. In some embodiments, the coating of the non-catalyst material 92 onto the unbounded diamond particles may be in a range from about 0.001 μm to about 10 μm.
The diamond particles 90 and the non-catalyst material 92 may be dry mixed with one another using, for example, a commercial TURBULA® Shaker-Mixer available from Glen Mills, Inc. of Clifton, N.J. or an acoustic mixer available from Resodyn Acoustic Mixers, Inc. of Butte, Mont. to provide a generally uniform and well mixed combination. In other embodiments, the mixing particles may be placed inside a bag or container and held under vacuum or in a protective atmosphere during the blending process.
In other embodiments, the non-catalyst material 92 may be positioned separately from the diamond particles 90. During the first HPHT process, the non-catalyst materials 92 may “sweep” from their original location and through the diamond particles 90, thereby positioning the non-catalyst materials 92 prior to sintering of the diamond particles 90. Subsequent to sweeping of the non-catalyst materials 92, the catalyst material 94 may be swept through the diamond particles 90 during the first HPHT process, thereby promoting formation of inter-diamond bonds between the diamond particles 90 and sintering of the diamond particles 90 to form the polycrystalline diamond body 120 of the polycrystalline diamond compact 80.
The diamond particles 90 and the non-catalyst material 92 may be positioned within a cup 142 that is made of a refractory material, for example tantalum, niobium, vanadium, molybdenum, tungsten, or zirconium, as shown in step 204. The support substrate 144 is positioned along an open end of the cup 142 and is optionally welded to the cup 142 to form cell assembly 140 that encloses diamond particles 90 and the non-catalyst material 92. The support substrate 144 may be selected from a variety of hard phase materials including, for example, cemented tungsten carbide, cemented tantalum carbide, or cemented titanium carbide. In one embodiment, the support substrate 144 may include cemented tungsten carbide having free carbons, as described in U.S. Provisional Application Nos. 62/055,673, 62/055,677, and 62/055,679, the entire disclosures of which are hereby incorporated by reference. The support substrate 144 may include a pre-determined quantity of catalyst material 94. Using a cemented tungsten carbide-cobalt system as an example, the cobalt is the catalyst material 94 that is infiltrated into the diamond particles 90 during the HPHT process. In other embodiments, the cell assembly 140 may include additional catalyst material (not shown) that is positioned between the support substrate 144 and the diamond particles 90. In further other embodiments, the cell assembly 140 may include non-catalyst material 92 that is positioned between the diamond particles 90 and the support substrate 144 or between the diamond particles 90 and the additional catalyst material (not shown).
The cell assembly 140, which includes the diamond particles 90, the non-catalyst material 92, and the support substrate 144, is introduced to a press that is capable of and adapted to introduce ultra-high pressures and elevated temperatures to the cell assembly 140 in an HPHT process, as shown in step 208. The press type may be a belt press, a cubic press, or other suitable presses. The pressures and temperatures of the HPHT process that are introduced to the cell assembly 140 are transferred to contents of the cell assembly 140. In particular, the HPHT process introduces pressure and temperature conditions to the diamond particles 90 at which diamond is stable and inter-diamond bonds form. The temperature of the HPHT process may be at least about 1000° C. (e.g., about 1200° C. to about 1800° C., or about 1300° C. to about 1600° C.) and the pressure of the HPHT process may be at least 4.0 GPa (e.g., about 4.0 GPa to about 12.0 GPa, or about 5.0 GPa to about 10 GPa, or about 5.0 GPa to about 8.0 GPa) for a time sufficient for adjacent diamond particles 90 to bond to one another, thereby forming an integral PCD compact having the polycrystalline diamond body 120 and the support substrate 144 that are bonded to one another.
Subsequent to formation of the integral PCD, the polycrystalline diamond body 120 may be separated from the support substrate 144 using a variety of conventionally known techniques, including chemically dissolution and machining techniques, such as grinding, electrical discharge machining, or laser ablation, as shown in step 210. The polycrystalline diamond body 120 may be separated from a majority of the support substrate 144 with a portion of the support substrate 144 remaining integral with the polycrystalline diamond body 120. Following removal of the support substrate 144, the polycrystalline diamond body 120 is machined to a desired shape for subsequent processing. The polycrystalline diamond body 120 may be shaped into a cylindrical shaped disc in which generally planar faces and a generally cylindrical body of the polycrystalline diamond body 120 are formed.
The introduction of the non-catalyst material 92 to the polycrystalline diamond body 120 prior to the first HPHT process may result in a reduction of catalyst material 94 that is present in the polycrystalline diamond body 120 following the HPHT process and prior to initiation of any subsequent leaching process. As compared to conventional cutting elements that are produced without the introduction of the non-catalyst material 92, unleached diamond bodies 120 produced according to the present disclosure may contain, for example, about 10% less catalyst material 94 when evaluated prior to leaching.
The polycrystalline diamond body 120 may undergo a leaching process in which the catalyst material is removed from the polycrystalline diamond body 120. In one example of a leaching process, the polycrystalline diamond body 120 is introduced to a leaching agent of an acid bath to remove the remaining support substrate 144 from the polycrystalline diamond body 120, as shown in step 212. The leaching process may also remove non-catalyst material 92 and catalyst material 94 from the polycrystalline diamond body 120 that is accessible to the acid. Suitable acids may be selected based on the solubility of the non-catalyst material 92 and the catalyst material 94 that is present in the polycrystalline diamond body. Examples of such acids include, for example and without limitation, ferric chloride, cupric chloride, nitric acid, hydrochloric acid, hydrofluoric acid, aqua regia, or solutions or mixtures thereof. The acid bath may be maintained at an pre-selected temperature to modify the rate of removal of the non-catalyst material 92 and the catalyst material 94 from the polycrystalline diamond body 120, including being in a temperature range from about 10° C. to about the boiling point of the leaching agent. In some embodiments, the acid bath may be maintained at elevated pressures that increase the liquid boiling temperature and thus allow the use of elevated temperatures, for example being at a temperature of greater than the boiling point of the leaching agent. The polycrystalline diamond body 120 may be subjected to the leaching process for a time sufficient to remove the desired quantity of non-catalyst material 92 and catalyst material 94 from the polycrystalline diamond body. The polycrystalline diamond body 120 may be subjected to the leaching process for a time that ranges from about one hour to about one month, including ranging from about one day to about 7 days.
In some embodiments, the polycrystalline diamond body 120 may be maintained in the leaching process until the polycrystalline diamond body 120 is at least partially leached. In polycrystalline diamond bodies 120 that are partially leached, the exterior regions of the polycrystalline diamond bodies 120 that are positioned along the outer surfaces of the polycrystalline diamond bodies 120 have the accessible interstitial regions depleted of non-catalyst material 92 and/or catalyst material 94, while the interior regions of the polycrystalline diamond bodies 120 are rich with non-catalyst material 92 and/or catalyst material 94. In other embodiments, the polycrystalline diamond body 120 may be maintained in the acid bath until complete leaching of the polycrystalline diamond body 120 is realized. Complete leaching of the polycrystalline diamond body 120 may be defined as removal from the polycrystalline diamond body 120 of all of the non-catalyst material 92 and the catalyst material 94 that is accessible to the leaching media.
In some embodiments, the extent of the leaching may be monitored by weighing the polycrystalline diamond body 120 after a pre-defined period of time. As the change in the weight loss of the polycrystalline diamond body 120 approaches a threshold value (for example, 10% loss of the unleached polycrystalline diamond body 120), the polycrystalline diamond body 120 may be considered to be completely leached. Because the polycrystalline diamond body 120 is leached without the support substrate 144, the leach fronts may extend from opposing sides of the polycrystalline diamond body 120 and from the perimeter surface of the polycrystalline diamond body 120. When the leach fronts from the opposing sides of the polycrystalline diamond body 120 meet, the polycrystalline diamond body 120 may be considered to be completely leached. In some embodiments, the extent of leaching may be monitored by the loss of density of the diamond body.
While some diamond bodies 120 may be at least partially leached, reference is made below to a completely leached polycrystalline diamond body 120 to discuss the effects of the addition of the non-catalyst material 92 to the polycrystalline diamond body 120.
In some embodiments, an unleached polycrystalline diamond body may have non-catalyst material 92 and catalyst material 94 at greater than about 4 vol. % of the polycrystalline diamond body 120, including being from about 4 vol. % to about 15 vol. %. In comparison, a completely leached polycrystalline diamond body 120 may have non-catalyst material 92 and catalyst material 94 that is less than about 50% less than the unleached polycrystalline diamond body 120, for example at about 42 vol. % less than the polycrystalline diamond body 120. A completely leached polycrystalline diamond body 120 may have non-catalyst material 92 and catalyst material 94 being from about 0.25 vol. % to about 6 vol. %, for example, being from about 0.2 vol. % to about 1 vol. %. In general, the extent of loss of non-catalyst material and catalyst material in a completely leached polycrystalline diamond body 120 is determined the material structure and composition, for example by the precursor diamond grain size and the particle size distribution.
As discussed above, the introduction of the non-catalyst material to the polycrystalline diamond body 120 reduces the concentration of the catalyst material 94 in the polycrystalline diamond body 120 prior to leaching. The introduction of the non-catalyst material 92 to the polycrystalline diamond body 120 also reduces the concentration of the trapped catalyst material 94 that remains present in the trapped interstitial volumes of the polycrystalline diamond body 120 following complete leaching of the polycrystalline diamond body 120. As compared to conventional cutting elements that are produced without the introduction of the non-catalyst material 92, diamond bodies 120 produced according to the present disclosure contain from about 30 vol. % to about 90 vol. % less catalyst material 94 following complete leaching of both of the compared diamond bodies.
The introduction of the non-catalyst material 92 to the polycrystalline diamond body 120 may also increase the leaching rate of the polycrystalline diamond body 120, such that the duration of time required to obtain complete leaching of the polycrystalline diamond body 120 is reduced as compared to conventionally produced diamond bodies. For example, complete leaching of the polycrystalline diamond body 120 having non-catalyst material 92 according to the present disclosure may be obtained from about 30% to about 60% less time as compared to conventional cutting elements that are produced without the introduction of the non-catalyst material 92. In one example, when evaluated after 7 days of introduction to the leaching process, polycrystalline diamond bodies 120 produced according to the present disclosure exhibited from about 40% to about 70% more mass loss than conventional PCD compacts.
Following complete leaching of the polycrystalline diamond body 120, the polycrystalline diamond body 120 continues to exhibit non-diamond components that are present in the trapped interstitial regions of the polycrystalline diamond body 120 that are positioned between bonded diamond grains in at least detectable amounts. However, the reduction of the non-diamond components (including catalyst material 94) in the leaching process accessible interstitial regions reduces the content of catalyst material 94 in the polycrystalline diamond body 120 and increases the thermal stability of the polycrystalline diamond body 120.
Referring again to FIG. 4, the completely leached polycrystalline diamond body 120 is assembled into a second cell in which the polycrystalline diamond body 120 is attached to a support substrate 110 (a second support substrate 110) and optionally a crown precursor material 400, as shown in step 214. The polycrystalline diamond body 120 is positioned proximate to the support substrate 110 and assembled into a cell assembly 240. The support substrate 110 may be selected from a variety of hard phase materials including, for example, cemented tungsten carbide, cemented tantalum carbide, or cemented titanium carbide. In one embodiment, the support substrate 110 may include cemented tungsten carbide having free carbons, as described in U.S. Provisional Application Nos. 62/055,673, 62/055,677, and 62/055,679, the entire disclosures of which are hereby incorporated by reference. This second support substrate 110 may be made from the same material as the first support substrate 144 discussed above. Alternatively, the second support substrate 110 may be made from a dissimilar material from the first support substrate 144 discussed above. The support substrate 110 may include a quantity of catalyst material 94. The support substrate 144 may have an intergranular phase liquidus temperature below 1300° C. at high pressure conditions. Using a cemented tungsten carbide-cobalt system as an example, the cobalt is the catalyst material 94 that is infiltrated into the at least partially leached polycrystalline diamond body 120 during a second HPHT process. In other embodiments, the cell assembly 240 may include additional catalyst material (not shown) that is positioned between the support substrate 110 and the polycrystalline diamond body 120. The cell assembly 240 includes pressure transferring agent 152 that at least partially surround the polycrystalline diamond body 120 and the support substrate 110.
The cell assembly 140, which includes the polycrystalline diamond body 120 and the support substrate 110, is introduced to a press that is capable of and adapted to introduce ultra-high pressures and elevated temperatures to the cell assembly 140 in a second HPHT process, as shown in step 216. The pressures and temperatures of the HPHT process that are introduced to the cell assembly 140 are transferred to contents of the cell assembly 140. In particular, the HPHT process introduces pressure and temperature conditions to the polycrystalline diamond body 120 at which diamond phase is thermodynamically stable. In other embodiments, the HPHT process introduces pressure and temperature conditions to the polycrystalline diamond body 120 at which diamond phase is unstable, which may lead to the formation of non-diamond carbon forms. The temperature of the HPHT process may be selected to be above the melting temperature of the infiltrating material. In one embodiment, the HPHT process may be operated at a temperature of at least about 1000° C. (e.g., about 1200° C. to about 1600° C., or about 1200° C. to about 1300° C.) and the pressure of the HPHT process may be at least 4.0 GPa (e.g., about 5.0 GPa to about 12.0 GPa, or about 5.0 GPa to about 10.0 GPa, or about 6.0 GPa to about 7.5 GPa) for a time sufficient for catalyst material 94 to infiltrate the polycrystalline diamond body 120, thereby bonding the polycrystalline diamond body 120 to the support substrate 110 and forming an integral PCD compact 82.
Following formation of the integral PCD compact 82, the PCD compact 82 may be processed through a variety of finishing operations to remove excess material from the PCD compact 82 and configure the PCD compact 82 for use by an end user, including formation of a PCD cutting element 84, as shown in step 218. Such finishing operations may include, for example, grinding and polishing the outside diameter of the PCD compact 82, cutting, grinding, lapping, and polishing the opposing faces (both the support-substrate-side face and the diamond-body-side face) of the PCD compact 82, and grinding and lapping a chamfer into the PCD compact 82 between the diamond-body-side face and the outer diameter of the PCD compact 82.
Referring now to FIG. 5, a plurality of PCD cutting elements 100 according to the present disclosure may be installed in a drill bit 310, as conventionally known, to perform a downhole drilling operation. The drill bit 310 may be positioned on a drilling assembly 300 that includes a drilling motor 302 that applies torque to the drill bit 310 and an axial drive mechanism 304 that is coupled to the drilling assembly for moving the drilling assembly 300 through a borehole 60 and operable to modify the axial force applied by the drill bit 310 in the borehole 60. Force applied to the drill bit 310 is referred to as Weight on Bit” (“WOB”). The drilling assembly 300 may also include a steering mechanism that modifies the axial orientation of the drill assembly 300, such that the drill bit 310 can be positioned for non-linear downhole drilling.
The drill bit 310 includes a stationary portion 312 and a material removal portion 314. The material removal portion 314 may rotate relative to the stationary portion 312. Torque applied by the drilling motor 302 rotates the material removal portion 314 relative to the stationary portion 312. A plurality of PCD cutting elements 100 according to the present disclosure are coupled to the material removal portion 314. The plurality of PCD cutting elements 100 may be coupled to the material removal portion 314 by a variety of conventionally known methods, including attaching the plurality of PCD cutting elements 100 to a corresponding plurality of shanks 316 that are coupled to the material removal portion 314. The PCD cutting elements 100 may be coupled to the plurality of shanks 316 by a variety of methods, including, for example, brazing, adhesive bonding, or mechanical affixation. In embodiments in which the PCD cutting elements 100 are brazed to the shanks 316 with a braze filler 318, at least a portion of the shanks 316, the braze filler 318, and at least a portion of the support substrate 110 of the PCD cutting element 100 is heated to an elevated temperature while in contact with one another. As the components decrease in temperature, the braze filler 318 solidifies and forms a bond between the support substrate 110 of the PCD cutting element 100 and the shanks 316 of the material removal portion 314. In one embodiment, the brazing filler 318 has a melting temperature that is greater than a melting temperature of the non-catalyst material 92 of the polycrystalline diamond body 120 at ambient pressure conditions. In another embodiment, the brazing filler 318 has a melting temperature that is less than the catalyst material 94 of the polycrystalline diamond body 120 at ambient pressure conditions. In yet another embodiment, the brazing filler 318 has a melting temperature that is less than the liquidus temperature of the catalyst material 94 of the polycrystalline diamond body at ambient pressure conditions.
When the drill bit 310 is positioned in the borehole 60, the material removal portion 314 rotates about the stationary portion 312 to reposition the PCD cutting elements 100 relative to the borehole 60, thereby removing surrounding material from the borehole 60. Force is applied to the drill bit 310 by the axial drive mechanism 304 in generally the axial orientation of the drill bit 310. The axial drive mechanism 304 may increase the WOB, thereby increasing the contact force between the PCD cutting elements 100 and the material of the borehole 60. As the material removal portion 314 of the drill bit 310 continues to rotate and WOB is maintained on the drill bit 310, the PCD cutting elements 100 abrade material of the borehole 60, and continue the path of the borehole 60 in an orientation that generally corresponds to the axial direction of the drill bit 310.
The temperature of the PCD cutting elements 100 may increase with increasing WOB, increasing material removal rates, and increasing cutting element wear. As discussed hereinabove, the increase in temperature may contribute to an increase in cutting element wear cause by back-conversion of diamond to non-diamond carbon forms. Further, the increase in temperature may increase stresses in the diamond lattice caused by mismatch in the coefficients of thermal expansion of the diamond grains and the catalyst material. In some embodiments, the operating temperature of the PCD cutting elements 100 at locations proximate to contact with the borehole 60 may have a temperature of greater than about 400° C., including having a temperature of greater than about 500° C., including having a temperature of greater than about 600° C., including have a temperature of greater than about 700° C. In some embodiments, the operating temperature of the PCD cutting elements 100 at locations proximate to contact with the borehole 60 may be greater than the melting temperature of the non-catalyst material 92 of the polycrystalline diamond body 120.
It should now be understood that PCD cutting elements according to the present disclosure include a polycrystalline diamond body that is coupled to a substrate. The polycrystalline diamond body has a plurality of diamond grains that define a plurality of interstitial regions between bonded diamond grains. Trapped interstitial regions prevent exposure of the interstitial regions to a leaching agent, such as acid. Non-catalyst material and catalyst material is present in these trapped interstitial regions. The non-catalyst material is distributed throughout the polycrystalline diamond body and is present in a detectable amount throughout the polycrystalline diamond body. The non-catalyst material remains in the polycrystalline diamond body from the manufacturing process. The non-catalyst material results in an increase in the leach rate of the PCD compact and in a reduction of catalyst material that is present in the trapped interstitial regions of the polycrystalline diamond body. The reduction of the catalyst material in the trapped interstitial regions of the polycrystalline diamond body increases the abrasion resistance of the PCD cutting element at elevated temperatures.

EXAMPLES

Example 1 (Comparative)

A series of conventional cutting elements were made in a HPHT process. Each of the cutting elements was made according to the following procedure. Diamond particles having a D50 particle size of about 21 μm were positioned in a refractory metal cup. The diamond particles exhibited high purity and were free of contaminants. A cemented tungsten carbide substrate having about 10 wt. % cobalt (acting as the catalyst) and a planar interface was inserted into the refractory metal cup and positioned proximate to the diamond particles. A reaction cell was assembled in which the refractory metal cup, the diamond particles, and the substrate were positioned inside a plurality of salt rings. The reaction cell assembly was installed within a belt-type press in which high pressure and high temperature were applied. The contents of the reaction cell were subjected to a maximum temperature of about 1500° C. and a maximum pressure of about 7 GPa. The contents of the reaction cell were maintained above the temperature of cobalt for about 2 minutes. The HPHT process produced a recovered polycrystalline body with good sinter quality.
The recovered polycrystalline body was processed to make a “double-pressed” cutting element. The recovered polycrystalline body was separated from the first substrate and machined to dimensional size by grinding the outer diameter, the working surface of the polycrystalline diamond body, and the attachment surface opposite the working surface to form the polycrystalline diamond body. Following machining and prior to leaching of one illustrative polycrystalline diamond body, the polycrystalline diamond body was evaluated by X-ray fluorescence and determined to contain about 9.09 wt. % cobalt along the side proximate to the substrate and about 9.61 wt. % cobalt along the side distal from the substrate. Further, the polycrystalline diamond body was determined to have about 3.04 wt. % tungsten along the side proximate to the substrate and about 2.48 wt. % tungsten along the side distal from the substrate (in either elemental form or in solid solution as tungsten carbide).
The cutting element was introduced to a leaching agent that reacted with the materials present in the interstitial regions of the cutting element that are positioned between diamond grains. The cutting element was fully submerged in the leaching agent such that all of the exterior surfaces of the polycrystalline diamond body were introduced to the leaching agent.
The cutting element was periodically removed from the leaching agent, flushed of leaching agent to dilute the leaching agent, dried, weighted, and evaluated to determine the weight loss of the polycrystalline diamond body. The presented data is plotted in FIG. 6 and labeled as “Example 1.” Variation in the weight loss at various depicted time points may be attributed to normal variation in the manufacturing process.
The weight loss of the cutting elements subjected to the leaching process increased asymptotically towards a maximum value, at which point the polycrystalline diamond body was considered to be fully leached of catalyst material and non-catalyst material from the interstitial regions. The cutting elements according to the present example were leached until there was a weight loss of about 10.5% was achieved. The weight loss depicted in FIG. 6 with reference to Example 1 is indicative of a conventional leaching rate profile.
Following leaching of the illustrative polycrystalline diamond body, the polycrystalline diamond body was evaluated by X-ray fluorescence and determined to contain about 2.81 wt. % cobalt along the side proximate to the substrate and about 2.78 wt. % cobalt along the side distal from the substrate. Further, the polycrystalline diamond body was determined to have about 0.835 wt. % tungsten along the side proximate to the substrate and about 0.819 wt. % tungsten along the side distal from the substrate (in either elemental form or in solid solution as tungsten carbide).

Example 2

Cutting elements according to the present disclosure were made according to the method described with respect to Example 1 above, however, prior to depositing the diamond particles in the refractory cup, the diamond particles were mixed with 1.6 wt. % lead particles having a D50 of about 20 μm. The reaction cell assembly that included the refractory cup, the diamond particles mixed with lead particles, and the substrate was subjected to the HPHT process having the same maximum temperature and pressure as Example 1 and held at a temperature above the melting temperature of cobalt for the same duration as Example 1. The HPHT process produced a recovered polycrystalline body with good sinter quality.
The cutting element was introduced to a leaching agent that reacted with the materials present in the interstitial regions of the cutting element that are positioned between diamond grains. The cutting element was fully submerged in the leaching agent such that all of the exterior surfaces of the polycrystalline diamond body were introduced to the leaching agent.
The cutting element was periodically removed from the leaching agent, flushed of leaching agent to dilute the leaching agent, dried, weighted, and evaluated to determine the weight loss of the polycrystalline diamond body. The presented data is plotted in FIG. 6 and labeled as “Example 2.” Variation in the weight loss at various depicted time points may be attributed to normal variation in the manufacturing process.
The weight loss of the cutting elements subjected to the leaching process increased asymptotically towards a maximum value, at which point the polycrystalline diamond body was considered to be fully leached of catalyst material and non-catalyst material from the interstitial regions. The cutting elements according to the present example were leached until there was a weight loss of about 11.8% was achieved.
As depicted in FIG. 6, the rate of removal of material during the leaching operation for cutting elements made according to Example 2 exceeds the rate of removal of cutting elements made according to Example 1. For example, when extrapolated from the provided data, at every time interval, the weight loss of cutting elements made according to Example 2 exceed the weight loss of cutting elements made according to Example 1. At 5 days, the extrapolated weigh loss of cutting elements made according to Example 2 exceeds the weight loss of cutting elements made according to Example 1 by about 60%; at 10 days, by about 50%; at 15 days, by about 50%.

Example 3

Cutting elements according to the present disclosure were made according to the method described with respect to Example 1 above, however, prior to depositing the diamond particles in the refractory cup, the diamond particles were mixed with 2.8 wt. % lead particles having a D50 of about 20 μm. The reaction cell assembly that included the refractory cup, the diamond particles mixed with lead particles, and the substrate was subjected to the HPHT process having the same maximum temperature and pressure as Example 1 and held at a temperature above the melting temperature of cobalt for the same duration as Example 1. The HPHT process produced a recovered polycrystalline body with good sinter quality.
Following machining and prior to leaching of one illustrative polycrystalline diamond body, the polycrystalline diamond body was evaluated by X-ray fluorescence and determined to contain about 9.31 wt. % cobalt along the side proximate to the substrate and about 8.84 wt. % cobalt along the side distal from the substrate. Further, the polycrystalline diamond body was determined to have about 2.39 wt. % tungsten along the side proximate to the substrate and about 3.26 wt. % tungsten along the side distal from the substrate (in either elemental form or in solid solution as tungsten carbide).
The cutting element was introduced to a leaching agent that reacted with the materials present in the interstitial regions of the cutting element that are positioned between diamond grains. The cutting element was fully submerged in the leaching agent such that all of the exterior surfaces of the polycrystalline diamond body were introduced to the leaching agent.
The cutting element was periodically removed from the leaching agent, flushed of leaching agent to dilute the leaching agent, dried, weighted, and evaluated to determine the weight loss of the polycrystalline diamond body. The presented data is plotted in FIG. 6 and labeled as “Example 3.”
The weight loss of the cutting elements subjected to the leaching process increased asymptotically towards a maximum value, at which point the polycrystalline diamond body was considered to be fully leached of catalyst material and non-catalyst material from the interstitial regions. The cutting elements according to the present example were leached until there was a weight loss of about 12.5% was achieved.
As depicted in FIG. 6, the rate of removal of material during the leaching operation for cutting elements made according to Example 3 exceeds the rate of removal of cutting elements made according to Example 1. For example, when extrapolated from the provided data, at every time interval, the weight loss of cutting elements made according to Example 3 exceed the weight loss of cutting elements made according to Example 1. At 5 days, the extrapolated weigh loss of cutting elements made according to Example 3 exceeds the weight loss of cutting elements made according to Example 1 by about 90%; at 10 days, by about 90%; at 15 days, by about 65%.
Following leaching of the polycrystalline diamond body, the polycrystalline diamond body was evaluated by X-ray fluorescence and determined to contain about 2.80 wt. % cobalt along the side proximate to the substrate and about 1.81 wt. % cobalt along the side distal from the substrate. Further, the polycrystalline diamond body was determined to have about 0.784 wt. % tungsten along the side proximate to the substrate and about 0.458 wt. % tungsten along the side distal from the substrate (in either elemental form or in solid solution as tungsten carbide).
As illustrated by Examples 2 and 3 in comparison with Example 1, the introduction of the non-catalyst material into the polycrystalline diamond body may accelerate the rate of material removal from the polycrystalline diamond body.
Additionally, the introduction of non-catalyst material to the polycrystalline diamond body may introduce a gradient of in the cobalt (i.e., catalyst material) and tungsten (i.e., additional non-catalyst material from the substrate), where the materials are at a higher concentration at positions proximate to the substrate and at lower concentrations at positions distal from the substrate. In some embodiments, the rate of material removal may be accelerated in regions of the polycrystalline diamond body having comparatively high concentrations of non-catalyst material relative to catalyst material (i.e., at locations of relatively high lead concentration as compared to cobalt concentration).
It should now be understood that cutting elements and polycrystalline diamond bodies that are incorporated into cutting elements according to the present disclosure may incorporate a non-catalyst material into the interstitial regions between adjacent diamond grains. The non-catalyst material may have a higher rate of reaction than the catalyst material when both are exposed to a leaching agent. Cutting elements and polycrystalline diamond bodies incorporated into such cutting elements may exhibit increased leaching rates as compared to conventional cutting elements, such that leaching rate of embodiments according to the present disclosure exceed a conventional leaching rate by at least about 30%.

Claims

1. A method of forming a cutting element, comprising:

assembling a reaction cell comprising a plurality of diamond particles, a non-catalyst material, a catalyst material, and a substrate within a refractory metal container, wherein the non-catalyst material is generally immiscible in the catalyst material when both are held at the greater of the melting or liquidus temperature of the catalyst material or the non-catalyst material;

subjecting the reaction cell and its contents to a high pressure high temperature sintering process in which the catalyst material promotes formation of inter-diamond bonding between adjacent diamond particles to form a poly crystalline diamond body that is attached to the substrate;

contacting at least a portion of the polycrystalline diamond body with a leaching agent to remove catalyst material and non-catalyst material from the diamond body,

a conventional leaching profile comprising time measured along a first axis and a corresponding weight loss percentage presented along a second axis; and

wherein a leaching rate at which the catalyst material and the non-catalyst material are leached from the diamond body exceeds a conventional leaching rate profile by at least about 30%.

2. The method of claim 1, wherein the leaching rate of the catalyst material and the non-catalyst material exceeds the convention leaching rate profile by at least about 40%.

3. The method of claim 1, wherein the leaching rate of the catalyst material and the non-catalyst material exceeds the convention leaching rate profile by up to about 60%.

4. The method of claim 1, wherein a leached depth of 800 μιη from the working surface of the polycrystalline diamond body is achieved in less than about 7 days of exposure to the leaching agent.

5. The method of claim 4, wherein a leached depth of 800 μιη from the working surface of a polycrystalline diamond body according to the conventional leaching rate profile is achieved in about 10 days of exposure to the leaching agent.

6. The method according to claim 1, wherein the non-catalyst material has a lower liquidus or melting temperature than the liquidus or melting temperature of the catalyst material.

7. The method according to claim 1, wherein the non-catalyst material has a higher rate of reaction with the leaching agent than the catalyst material.

8. The method of claim 1, wherein high pressure high temperature sintering process includes:

melting the non-catalyst material and pushing the melted non-catalyst material through at least a portion of the plurality of diamond particles, thereby surrounding at least a portion of the plurality of individual diamond particles; and

melting the catalyst material and pushing the melted catalyst material through at least a portion of the plurality of diamond particles and displacing a portion of the non-catalyst material from interstitial regions between the individual diamond grains.

9. The method of claim 1, wherein the non-catalyst material is mixed with the diamond particles prior to being assembled in the reaction cell.

10. The method of claim 1, wherein the catalyst material is incorporated into the substrate.

11. The method of claim 1, wherein the catalyst material is positioned in a catalyst source that is separate from the substrate.

12. The method of claim 1, further comprising the selecting of a multimodal feed that comprises a first population of diamond particles having a first particle size distribution function and a second population of diamond particles having a second particle size distribution function.

13. The method of claim 12, wherein the multimodal feed further comprises a third population of diamond particles having a third particle size distribution function.

14. The method of claim 1, wherein the diamond body comprises a first portion positioned proximate to the substrate and having a first particle size distribution function and a second portion positioned distally from the substrate and having a second particle size distribution function.

15. The method of claim 14, wherein the first portion has a median particle size that is smaller than a median particle size of the second portion.

16. The method of claim 14, wherein the first portion has a median particle size that is larger than a median particle size of the second portion.

17. The method of claim 1, wherein the diamond body further comprises metal carbide, and a metal carbide concentration within the diamond body is less than about 70% of a conventional metal carbide concentration.

18. The method of claim 1, wherein the non-catalyst material is lead or alloys thereof.

19. The method of claim 1, wherein the non-catalyst material is bismuth or alloys thereof.

20. The method of claim 1, wherein the non-catalyst material is positioned between the diamond particles and the substrate.

21. A cutting element, comprising:

a substrate comprising a metal carbide and a catalyst material; and

a poly crystalline diamond body bonded to the substrate, the poly crystalline diamond body comprising a plurality of diamond grains bonded to adjacent diamond grains in diamond-to-diamond bonds and a plurality of interstitial regions positioned between adjacent diamond grains, the plurality of interstitial regions comprising an immiscible non-catalyst material, the catalyst material, the metal carbide, or combinations thereof,

wherein a metal carbide concentration within the diamond body is less than about 70% of a conventional metal carbide concentration.

22. The cutting element of claim 21, wherein the metal carbide comprises cemented tungsten carbide.

23. The cutting element of claim 21, wherein the non-catalyst material has a lower liquidus or melting temperature than the liquidus or melting temperature of the catalyst material.

24. The cutting element of claim 21, wherein the diamond particles comprise a multimodal population of bonded diamond grains that comprises a first population of diamond particles having a first particle size distribution function and a second population of diamond particles having a second particle size distribution function.

25. The cutting element of claim 24, wherein the multimodal population of bonded diamond grains further comprises a third population of diamond particles having a third particle size distribution function.

26. The cutting element of claim 21, wherein the poly crystalline diamond body comprises a first portion positioned proximate to the substrate and having a first particle size distribution function and a second portion positioned distally from the substrate and having a second particle size distribution function.

27. The cutting element of claim 26, wherein the first portion has a median particle size that is smaller than a median particle size of the second portion.

28. The cutting element of claim 26, wherein the first portion has a median particle size that is larger than a median particle size of the second portion.

29. A drill bit, comprising:

a bit body comprising a leading end structure for drilling a subterranean formation; and a plurality of cutting elements mounted to the blades, at least one of the plurality of cutting elements comprising:

a substrate comprising a metal carbide and a catalyst material; and a polycrystalline diamond body bonded to the substrate, the polycrystalline diamond body comprising a plurality of diamond grains bonded to adjacent diamond grains in diamond-to-diamond bonds, the polycrystalline diamond body further comprising a plurality of interstitial regions positioned between adjacent diamond grains, the plurality of interstitial regions comprising an immiscible non-catalyst material, catalyst material, metal carbide, or combinations thereof,

30. A method of forming a cutting element, comprising:

wherein the non-catalyst material has a higher rate of reaction with the leaching agent than the catalyst material.

31. The method of claim 30, wherein the non-catalyst material has a lower liquidus or melting temperature than the liquidus or melting temperature of the catalyst material.

32. The method of claim 30, wherein a leached depth of 800 μιη from the working surface of the diamond body is achieved in less than about 7 days of exposure to the leaching agent.

33. The method of claim 30, wherein the diamond body has a non-zero non-catalyst material concentration that increases from the substrate to the working surface,

wherein when leaching agent is contacted to the working surface, a reaction rate of the leaching reaction decreases with increasing distance from the working surface.