Patent Application
20150129322
Polycrystalline diamond (PCD) materials known in the art are formed from diamond grains or crystals and a ductile metal binder and are synthesized by high temperature/high pressure processes. Such material is well known for its mechanical properties of wear resistance, making it a popular material choice for use in such industrial applications as cutting tools for machining, and subterranean mining and drilling where such mechanical properties are highly desired. For example, conventional PCD can be provided in the form of surface coatings on, e.g., cutting elements used with cutting and drilling tools to impart improved wear resistance thereto.
Generally, PCD-containing cutting elements used in such applications are formed by coating a carbide substrate with a layer of PCD. Such cutting elements include a substrate, a surface layer, and often a transition layer to improve the bonding between the exposed layer and the substrate. The substrate is generally a carbide material, e.g., cemented carbide, tungsten carbide (WC) cemented with cobalt (WC—Co).
The PCD layer generally includes metal binder up to about 30 percent by weight. The metal binder facilitates diamond intercrystalline bonding, and bonding of diamond layer to the substrate. Metals employed as the binder are often selected from cobalt, iron, or nickel and/or mixtures or alloys thereof and may include metals such as manganese, tantalum, chromium and/or mixtures or alloys thereof. However, while higher metal binder content generally increases the toughness of the resulting PCD material, higher metal content also decreases the PCD material hardness and wear resistance, thus limiting the flexibility of being able to provide PCD coatings having desired levels of hardness, wear resistance and toughness. Additionally, when variables are selected to increase the hardness or wear resistance of the PCD material, generally brittleness also increases, thereby reducing the toughness of the PCD material.
Conventional PCD cutting elements may optionally include one or more transition layers between the PCD layer and the substrate. Such transition layers may include refractory particles such as carbides in addition to the diamond and metal binder to change material properties through the layers. However, carbide content manipulation does not necessarily promote the best transition between adjacent PCD layers, permitting discrete interfaces to exist between the layers which can promote unwanted stress concentrations. The existence of these discrete interfaces, and the resulting stress concentrations produced therefrom, can cause premature failure of the PCD cutting element by delamination along the layer-to-layer interfaces.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
In one aspect, embodiments disclosed herein relate to a cutting element that includes a substrate including a plurality of metal carbide particles and a first metal binder having a first metal binder content; an outer layer of polycrystalline diamond material at an end of the cutting element, the polycrystalline diamond material including: a plurality of interconnected diamond particles; and a plurality of interstitial regions disposed among the interconnected diamond particles, the plurality of interstitial regions contain a second metal binder having a second metal binder content; and at least one transition zone between the substrate and the outer layer, the at least one transition zone comprising a plurality of refractory metal carbide particles and a third metal binder having a third metal binder content, the third metal binder content being less than the first metal binder content and the second metal binder content.
In another aspect, embodiments disclosed herein relate to a method of forming a cutting element that includes placing a volume of diamond grains adjacent one or more transition volumes of a mixture of refractory metal particles and a carbon source, the one or more transition volumes comprising a first transition volume having at least 60 wt % refractory metal particles based on the total weight of the first transition volume; placing a metal carbide substrate material comprising a plurality of carbide particles and a metal binder adjacent the one or more transition volumes, opposite the volume of diamond grains; and subjecting the volume of diamond grains, one or more transition volumes, and the metal carbide substrate material to high pressure/high temperature sintering conditions to form a sintered polycrystalline diamond body attached to a substrate with at least one transition zone therebetween.
In yet another aspect, embodiments disclosed herein relate to a downhole cutting tool that includes a tool body and at least one cutting element fixed to the tool body, the cutting element including a substrate including a plurality of metal carbide particles and a first metal binder having a first metal binder content; an outer layer of polycrystalline diamond material at an end of the cutting element, the polycrystalline diamond material including: a plurality of interconnected diamond particles; and a plurality of interstitial regions disposed among the interconnected diamond particles, the plurality of interstitial regions contain a second metal binder having a second metal binder content; and at least one transition zone between the substrate and the outer layer, the at least one transition zone comprising a plurality of refractory metal carbide particles and a third metal binder having a third metal binder content, the third metal binder content being less than the first metal binder content and the second metal binder content.
Other aspects and advantages of the claimed subject matter will be apparent from the following description and the appended claims.
In one aspect, embodiments disclosed herein relate to use of transition zones (or transition layers) in polycrystalline diamond (PCD) cutting elements. Specifically, one or more embodiments disclosed herein relate to the formation of carbide particles in situ in the one or more transition zones, and the specific composition that may be used to form such carbide particles in a desirable manner. In one or more embodiments, the present disclosure also relates to a non-uniform metal content throughout the cutting element, and specifically in one or more transition zones, as compared to the polycrystalline diamond outer layer and/or carbide substrate. Methods for manufacturing a PCD cutting element that includes at least one transition zone between the PCD layer and the substrate and embodiments utilizing the disclosed cutting elements in various articles and apparatuses, such as rotary drill bits, mining and construction tools, bearing apparatuses, wire-drawing dies, machining equipment, and other articles and apparatuses are also disclosed.
As used herein, “polycrystalline diamond”, along with its abbreviation, “PCD”, or “a polycrystalline diamond material” refers to the three-dimensional network or lattice of bonded together or interconnected diamond grains. Specifically, the diamond to diamond bonding is catalyzed by a metal (such as cobalt) by a high temperature/high pressure process, whereby the metal remains in the regions between the particles. Thus, the metal particles added to the diamond particles may function as a catalyst and/or binder, depending on the exposure to diamond particles that can be catalyzed as well as the temperature/pressure conditions. For the purposes of this application, when a metallic component is referred to as a metal binder, it does not necessarily mean that no catalyzing function is also being performed, and when the metallic component is referred to as a metal catalyst, it does not necessarily mean that no binding function is also being performed.
Referring to
The above described transition zones include a plurality of refractory metal carbide particles. In one or more embodiments, such refractory metal carbide particles are not incorporated into the cutting element in a preexisting state, rather, the refractory metal carbide particles are formed in situ, by reaction of a refractory metal with carbon existing in the zone along with the refractory metal (present in the form of diamond particles, graphite particles, carbon black, carbon-containing wax, or other carbon sources, for example) at HPHT sintering conditions. That is, when an assembly of an unsintered mixture of diamond particles (or other carbon sources) and refractory metal is subjected to high pressure/high temperature conditions, the refractory metal and carbon may react in situ to form refractory metal carbide particles. Such reaction may be accompanied by grain growth of the refractory metal particles as the refractory metal forms refractory metal carbide. Such growth observed may include an initial refractory metal particle size of less than 5 microns, less than 3 microns, less than 2 microns, less than 1 micron or even less than 0.5 microns, resulting in a refractory metal carbide particle size of at least 5 microns, at least 6 microns, or at least 8 microns. In one or more embodiments, the refractory metal carbide particles may be less than 10 microns. However, to some extent, the final refractory metal carbide particle size may depend, in part, on the size of the initial refractory metal particles. Thus, when nanopowders are used, the final refractory metal carbide particles may have a greater particle size than the nanopowders, but still less than 5 microns, such as for example, at least 2 microns.
In various embodiments, the refractory metal particles may be any metal-carbide forming metal, such as W, Ta, Ti, Nb, Zr, mixtures thereof, etc.; however, particular embodiments may use tungsten metal. Further, depending on the type of carbon source being used, it is also within the scope of the present disclosure that the refractory metal may be coated with the carbon source, such as a carbon-containing polymer coating, such as polyethylene glycol or methoxypolyethylene glycol. In one or more other embodiments, a carbon-containing polymer coating may be substantially free of oxygen or other impurities may be used to coat refractory metal particles for use in forming the one or more transition layers (or outer layer, when included).
As mentioned above, the metal binder infiltrates from the substrate through the one or more transition zones and into the polycrystalline diamond layer. While metal binder may generally be provided to a mixture of diamond particles (to catalyze the formation of diamond to diamond bonds, to form polycrystalline diamond) from the substrate or included with a diamond mixture, one or more embodiments of the present disclosure only use metal binder that is provided from the substrate to infiltrate through the cutting element. Thus, the cup (e.g., sintering container or can), which is placed into a reaction cell and subjected to an HPHT process may include (1) a first volume of a mixture of diamond particles (free of a catalyzing metal binder and, optionally, consisting of diamond particles or consisting of diamond particles and non-catalyzing refractory metal), (2) an adjacent, second volume of a mixture of diamond particles with a refractory metal (free of a catalyzing metal binder and, optionally, consisting of diamond particles and non-catalyzing refractory metal), and (3) a preformed substrate or green substrate material of carbide particles and a (catalyzing) metal binder. Thus, when the assembled of volumes and substrate material is subjected to HPHT sintering conditions, the metal binder may infiltrate through the second volume to the first volume, thereby catalyzing the formation of the polycrystalline diamond microstructure. The inventors of the present application also theorize that by using an infiltrated metal binder (instead of a metal binder provided with the first or second volume), the infiltrating metal is at least partially saturated with carbon therein, and thus, when the infiltrating metal infiltrates through the second volume, such at least partial saturation further shifts the reaction equilibrium between the refractory metal and the carbon (present in diamond particles) towards formation of refractory metal carbides. Further, as the refractory metal carbide particles grow, the grain growth may physically push the infiltrating binder into one of the adjacent layers, such as the polycrystalline diamond layer and/or substrate, resulting in the non-uniform metal binder content throughout the cutting element, described above. For embodiments using more than one transition zone, one skilled in the art would appreciate that a third or fourth volume, etc., of diamond particles mixed with refractory metal particles (at differing ratios) may be provided in the assembly and subjected to HPHT sintering conditions. Further, one or more of the transition zones may have a higher hardness as well as higher strength and toughness than the substrate, which the present inventors believe results from the in situ formation of a refractory metal carbide and non-uniform metal binder content present in the one or more transition zones.
Further, in one or more embodiments, the amount of diamond incorporated into the second volume may be selected to optimize or increase refractory metal carbide formation. For example, if the refractory metal being used is tungsten, then atomic mass of both tungsten and carbon can be considered to ensure a greater conversion of refractory metal and diamond (or other carbon sources) to refractory metal carbide. Likewise, if lighter titanium is used, then the desired weight percent of titanium would likely shift downward. In one or more embodiments, a second volume may be provided with at least 60 wt % refractory metal, and a balance of diamond particles, or with at least 70, 80, or 85 wt % refractory metal in one or more other embodiments (and a balance diamond). Depending on the relative amount of diamond and refractory metal used, the amount of diamond particles remaining in the at least one transition layer may accordingly vary. For example, in the case of tungsten, where a 1:1 reaction of tungsten (having an atomic mass of 183.84 u) and carbon (having an atomic mass of 12.0107 u) results in a mass percent of 93.867% tungsten and 6.13% carbon, if 10 wt % of diamond were incorporated in the second volume, assuming the tungsten fully reacts with diamond, there may be less than 5 wt % of diamond remaining in the formed transition zone. In one or more embodiments, it may be particularly desirable to provide a second volume having diamond particles such that no more than 5 wt % of diamond particles would remain after reaction with the refractory metal, assuming full conversion of the refractory metal (and a 1:1 reaction). While theoretical 1:1 reactions are described, it is within the scope of the present disclosure that other carbides may be formed, such as W2C as well as complex carbides. However, depending on the number of transition zones to be incorporated into the cutting element, the appropriate diamond content (and thus, diamond content remaining after HPHT sintering) may be selected.
For example, in one or more embodiments, at least one transition zone includes a diamond content of less than 5 wt %, a refractory metal carbide content of up to 95 wt %, and a metal binder content of ranging from about 1 to 8 wt % (or 1 to 2 wt % in particular embodiments). However, as mentioned above, when two or more transition zones are included in a cutting element, the zone adjacent the PCD layer may have a diamond content that may be greater than 10 wt % (or ranging from 20-60 wt % in a particular embodiment), the refractory metal carbide content may be less than 90 wt % (or ranging from 40-80 wt % in particular embodiments), and the metal binder content of at least one transition zone may be 1 to 8 wt %. In one or more embodiments, such transition zone having such greater diamond content may be used in combination with a zone adjacent the substrate having a diamond content of less than 5 wt %, a refractory metal carbide content of up to 95 wt %, and a metal binder content of ranging from about 1 to 8 wt %. Further, when two or more transition zones are present, at least one of the transition zones may have a metal binder content that is less than the metal binder content of the outer PCD layer and the substrate. In some embodiments, two or more transition zones may have the reduced metal binder content, but in other embodiments, one of the transition zones may have the reduced metal binder content, and another of the transition zones may have a binder content that is similar to the outer PCD layer and substrate.
As mentioned above, in one or more embodiments, the polycrystalline diamond outer layer may include a plurality of diamond particles, a metal binder residing in the interstitial spaces between the plurality of diamond particles, and optionally, a refractory metal also residing within the interstitial spaces. In such embodiments, the polycrystalline diamond material may include a diamond content of up to 94 wt %, a second metal binder content of at least 6 wt %, and a refractory metal content of up to 5 wt %.
The substrate may be formed from a suitable material such as tungsten carbide, tantalum carbide, or titanium carbide. In the substrate, metal carbide grains are supported by a matrix of a metal binder. Thus, various binding metals may be present in the substrate, such as cobalt, nickel, iron, alloys thereof, or mixtures, thereof. In a particular embodiment, the substrate may be formed of a sintered tungsten carbide composite structure of tungsten carbide and cobalt. However, it is known that various metal carbide compositions and binders may be used in addition to tungsten carbide and cobalt. Thus, references to the use of tungsten carbide and cobalt are for illustrative purposes, and no limitation on the type of carbide or binder use is intended. In one or more embodiments, the substrate may include a metal carbide content of at least 85 wt %, and a metal binder content of at least 6 wt %. Such cemented carbides may include those described for example as 406, 313/314, 614, etc., as well as other carbide blends having the described metal content (and a particle size that balances the desired metal content).
As mentioned above, the cutting elements of the present disclosure may be formed by sintering the precursor materials to HPHT sintering conditions. Specifically, a polycrystalline diamond material may be formed by placing an unsintered mass of diamond crystalline particles within a metal enclosure of a reaction cell of a HPHT apparatus and subjecting individual diamond crystals to sufficiently high pressure and high temperatures (sintering under HPHT conditions) that intercrystalline bonding occurs between adjacent diamond crystals. A metal catalyst, such as cobalt or other Group VIII metals, may be provided to the unsintered mass of crystalline particles to promote intercrystalline diamond-to-diamond bonding by infiltration from the substrate (or substrate material) into the diamond grains during HPHT sintering.
The reaction cell is then placed under processing conditions sufficient to cause the intercrystalline bonding between the diamond particles. It should be noted that if too much additional non-diamond material, such as tungsten carbide or cobalt is present in the powdered mass of crystalline particles, appreciable intercrystalline bonding is prevented during the sintering process. Such a sintered material where appreciable intercrystalline bonding has not occurred is not within the definition of PCD.
The transition layers may similarly be formed by placing an unsintered second volume of diamond particles and refractory metal within the HPHT apparatus, adjacent the unsintered mass of diamond particles forming the polycrystalline diamond layer. The reaction cell is then placed under processing conditions sufficient to cause sintering of the material to create the transition zone. Additionally, a preformed metal carbide substrate precursor substrate materials may be included adjacent the second volume, opposite from the first volume forming the polycrystalline diamond layer. During the HPHT sintering conditions, the polycrystalline diamond layer is formed, as well as joined to the substrate through the transition zone(s).
In one or more embodiments, a minimum temperature is about 1200° C., and a minimum pressure is about 35 kilobars. In specific embodiments, processing may be at a pressure of about 45-90 kilobars and a temperature of about 1300-2000° C. The minimum sufficient temperature and pressure in a given embodiment may depend on other parameters such as the presence of a catalytic material, such as cobalt. Generally, the diamond crystals will be subjected to the HPHT sintering in the presence of a diamond catalyst material, such as cobalt, to form an integral, tough, high strength mass or lattice. The catalyst, e.g., cobalt, may be used to promote recrystallization of the diamond particles and formation of the lattice structure, and thus, cobalt particles are generally found within the interstitial spaces in the diamond lattice structure. Those of ordinary skill will appreciate that a variety of temperatures and pressures may be used, and the scope of the present disclosure is not limited to specifically referenced temperatures and pressures.
Application of the HPHT processing will cause diamond crystals to sinter and form a polycrystalline diamond layer. Similarly, application of HPHT to the second volume will cause the diamond crystals and refractory metal particles to react, forming refractory metal carbide particles that are sintered together by the metal binder infiltrating through from the substrate such that the refractory metal carbide particles are no longer in the form of discrete particles that can be separated from each other. Further, each of the layers bond to each other and to the substrate during the HPHT process.
It is also within the scope of the present disclosure that the polycrystalline diamond outer layer may have at least a portion of the metal catalyst removed therefrom, such as by leaching the diamond layer with a leaching agent (often a strong acid). In a particular embodiment, at least a portion of the diamond layer may be leached in order to gain thermal stability without losing impact resistance.
The variations in the particle sizes of the refractory metal and resulting refractory metal carbide particle due to grain growth were discussed above. In addition to controlling the refractory metal particle size, the particle size of the diamond particles used in the first volume (as well as the second (or third, etc) volume(s)) may also be controlled. Generally, a particle size ranging from about 0.5 to 100 microns (or 4 to 30 microns in particular embodiments) may be used; however, it is also within the scope of the present disclosure that smaller particle sizes may be used, including in the nanorange, such as for mixture in the second volume, used to form a transition zone. Within the 4-30 micron range, certain types of cutting elements may have particularly desirable sub-ranges. For example, for an insert (illustrated in
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The polycrystalline diamond outer layer may have a thickness of at least 0.006 inches in one embodiment, and at least 0.020 inches or 0.040 inches in other embodiments. As used herein, the thickness of any polycrystalline diamond layer refers to the maximum thickness of that layer, as the diamond layer may vary in thickness across the layer. Specifically, it is within the scope of the present disclosure that the thickness of a polycrystalline diamond layer may vary so that the thickness is greatest within the zone of the cutting element that engages the formation. It is expressly within the scope of the present disclosure that a polycrystalline diamond layer may vary or taper such that it has a non-uniform thickness across the layer. Such variance in thickness may generally result from the use of non-uniform upper surfaces of the insert body/substrate in creating a non-uniform interface. In one or more particular embodiments, a non-uniform interface may be used that includes a dome or generally convex interface, particularly when used in combination with the substantially pointed cutting elements illustrated in
The cutting elements of the present disclosure may find particular use in roller cone bits and hammer bits. Roller cone rock bits include a bit body adapted to be coupled to a rotatable drill string and include at least one “cone” that is rotatably mounted to the bit body. Referring to
Hammer bits generally are impacted by a percussion hammer while being rotated against the earth formation being drilled. Referring to
The cutting inserts of the present disclosure may have a body having a cylindrical grip portion from which a convex protrusion extends. The grip is embedded in and affixed to the roller cone or hammer bit, and the protrusion extends outwardly from the surface of the roller cone or hammer bit. The protrusion, for example, may be hemispherical, which is commonly referred to as a semi-round top (SRT), or may be conical, or chisel-shaped, or may form a ridge that is inclined relative to the plane of intersection between the grip and the protrusion. In some embodiments, the polycrystalline diamond outer layer and one or more transition layers may extend beyond the convex protrusion and may coat the cylindrical grip.
Referring now to
A plurality of orifices 116 are positioned on the bit body 110 in the areas between the blades 120, which may be referred to as “gaps” or “fluid courses.” The orifices 116 are commonly adapted to accept nozzles. The orifices 116 allow drilling fluid to be discharged through the bit in selected directions and at selected rates of flow between the blades 120 for lubricating and cooling the drill bit 160, the blades 120 and the cutters 150. The drilling fluid also cleans and removes the cuttings as the drill bit 160 rotates and penetrates the geological formation. Without proper flow characteristics, insufficient cooling of the cutters 150 may result in cutter failure during drilling operations. The fluid courses are positioned to provide additional flow channels for drilling fluid and to provide a passage for formation cuttings to travel past the drill bit 160 toward the surface of a wellbore (not shown).
As described throughout the present disclosure, the cutting elements may be used on a variety of drill bit types. However, it is also within the scope of the present disclosure that the cutting elements may be included on a hole opener as well as other downhole cutting tools.
Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from this disclosure. Accordingly, all such modifications are intended to be included within the scope of this disclosure. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function.
This Application claims the benefit to and priority of U.S. Provisional Application 61/901,910 filed on Nov. 8, 2013, the entirety of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61901910 | Nov 2013 | US |
