Metal matrix composites for drilling tools

Abstract

An additive manufactured metal matrix composite (MMC) includes hard particles and a binder. The proportion of the hard particles in the MMC is greater than 27 vol%, and the hard particles are spherical. The binder includes at least nickel and silicon. The proportion of the binder in the MMC is less than 73 vol%. The silicon accounts for more than 6.0 wt% of the binder, but accounts for less than 12.5 wt% of the binder. The MMC has a lateral breaking strength (TRS) of greater than 200 ksi and a corrosion resistance coefficient of greater than 30.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 385,227, filed on November 29, 2022, entitled "METAL MATRIX COMPOSITES FOR DRILLING TOOLS", the disclosure of which is hereby incorporated by reference in its entirety. Background Art

[0003] Wellbore drilling is performed at a surface location or the seabed for various exploration or production purposes. For example, a wellbore can be drilled to access fluids (such as liquid and gaseous hydrocarbons) stored in subterranean formations and extract the fluids from the formations. Various drilling methods can be utilized, depending in part on the characteristics of the formations through which the wellbore is drilled.

[0004] During downhole drilling operations, cutting tools such as drill bits and reamers are used to remove material from the ground to extend or enlarge the borehole. Typically, the cutting tool includes a monolithic bit body, which can be made of steel or a hard composite matrix material composed of tungsten carbide and a metallic binder. The cutting elements are mounted along the outer surface of the bit body blades. The cutting elements for earth - drilling bits can include polycrystalline diamond compact (PDC) cutting teeth. Each PDC cutting tooth has a portion brazed into a groove or pocket formed in the blade.

[0005] The PDC cutting teeth are positioned along the leading edge of the bit body blades so that, as the bit body rotates, the PDC cutting teeth engage and drill into the formation. In use, significant forces can be applied to the PDC cutting teeth. Additionally, the bit and the PDC cutting teeth can be subject to considerable abrasive forces. In some cases, impact, vibration, and erosive forces can cause the bit to fail due to the loss of one or more cutting teeth or due to blade fracture.

[0006] While steel - body bits may have toughness and ductility, enabling them to resist cracking and failure caused by impact forces generated during drilling, steel is more susceptible to abrasive wear and erosive wear caused by high - velocity drilling fluids and abrasive particles. Abrasive particles can include portions of the formation carried by the drilling fluid, as well as sand, cuttings, etc. Typically, portions of steel - body PDC bits are coated with a more erosion - resistant material such as tungsten carbide overlay to improve erosion resistance.

[0007] Compared to steel bit bodies, tungsten carbide (WC) cemented carbide matrix bits have higher wear resistance and erosion resistance. Typical matrix bits used in today's industry are generally formed by filling a mold with tungsten carbide powder and then infiltrating the powder with a molten transition - metal alloy. Common metal alloys used to form the metal matrix are iron, nickel, copper, or their alloys.

[0008] The drill bit body is made of tungsten carbide or other hard metal matrix materials. Although it is more erosion-resistant than steel, it lacks toughness and strength. Therefore, it becomes brittle and prone to cracking when subjected to impact and fatigue stresses during drilling. This can cause one or more blades to crack and even lead to the fracture of the drill bit. The formation and propagation of cracks in the matrix may result in the loss of one or more PDC cutting teeth.

[0009] Cutting tools in downhole drilling environments are exposed to harsh conditions such as wear, erosion, impact, torque, and fatigue. These conditions can shorten the effective life of the drill bit body. Modifying the material and structure of the cutting tool may be beneficial. Summary of the Invention

[0010] An additive manufactured metal matrix composite (MMC) comprising hard particles and a binder. The hard particles account for more than 27 vol% of the MMC and are in a spherical shape. For example, spherically cast tungsten carbide particles account for more than 40 wt% of the MMC. The binder contains at least nickel and silicon. The binder accounts for less than 73 vol% of the MMC. For example, the binder accounts for less than 60 wt% of the MMC with SCC particles. The silicon accounts for more than 6.0 wt% but less than 12.5 wt% of the binder.

[0011] An additive manufactured metal matrix composite (MMC) includes printing a first layer of the MMC and at least partially printing a second layer of the MMC on the first layer. Each layer of the MMC contains a mixture of hard particles and binder powder. The hard particles account for between 30 vol% and 50 vol% of the MMC. The binder contains at least nickel and silicon. The silicon accounts for more than 6.0 wt% but less than 10.0 wt% of the binder powder.

[0012] A drilling tool having an additive manufactured metal matrix composite (MMC), the MMC comprising hard particles and a binder. The hard particles account for more than 30 vol% of the MMC and are spherically cast tungsten carbide particles. The binder accounts for less than 70 vol% of the MMC. The silicon accounts for more than 7.0 wt% but less than 10.0 wt% of the binder powder.

[0013] The present invention content is provided to introduce a series of concepts further described in the detailed description. The present invention content is not intended to identify the key or essential features of the claimed subject matter, nor is it intended to help limit the scope of the claimed subject matter. Additional features and aspects of the embodiments of the present disclosure will be set forth herein, and will be partly apparent from the description, or may be learned by practice of such embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] To describe the manner in which the above and other features of the present disclosure can be obtained, a more particular description will be presented by reference to specific embodiments shown in the drawings of the present disclosure. For better understanding, throughout the various drawings, the same elements have been denoted by the same reference numerals. Although some of the drawings may be schematic or exaggerated representations of concepts, at least some of the drawings may be drawn to scale. It should be understood that the drawings depict some example embodiments, and the embodiments will be described and explained more specifically and in detail by using the drawings, in which:

[0015] Figure 1 is a representation of a drill - down system according to at least one embodiment of the present disclosure;

[0016] Figure 2 is a side view of a downhole tool according to one or more embodiments of the present disclosure;

[0017] Figure 3 is an assembly drawing of a downhole tool having a metal - matrix composite (MMC) section and cutting elements according to one or more embodiments of the present disclosure;

[0018] Figure 4 is a cross - sectional micrograph of an example MMC according to one or more embodiments of the present disclosure;

[0019] Figure 5 is a cross - sectional micrograph of an example MMC according to one or more embodiments of the present disclosure;

[0020] Figure 6 is a graph showing the relationship between the transverse rupture strength (TRS) and the erosion resistance coefficient of various materials that can be used with a downhole tool according to one or more embodiments of the present disclosure;

[0021] Figure 7 is a graph showing the TRS of various materials that can be used with a downhole tool according to one or more embodiments of the present disclosure;

[0022] Figure 8 is a scanning electron microscope image of an MMC having a nickel - based binder containing silicon and boron according to one or more embodiments of the present disclosure;

[0023] Figure 9 A scanning electron microscope image of an MMC with a nickel-based binder containing silicon but not boron according to one or more embodiments of the present disclosure;

[0024] Figure 10 A scanning electron microscope image of a fracture surface of an MMC according to one or more embodiments of the present disclosure;

[0025] Figure 11 A scanning electron microscope image of a fracture surface of an MMC according to one or more embodiments of the present disclosure;

[0026] Figure 12 A graph showing the TRS of multiple MMC samples with binders having different silicon contents according to one or more embodiments of the present disclosure;

[0027] Figure 13 A graph showing the microhardness of various binders according to one or more embodiments of the present disclosure; and

[0028] Figure 14 A graph showing the erosion resistance coefficient of multiple MMC samples with binders having different silicon contents according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0029] The present disclosure generally relates to devices, systems, and methods for forming drill bits, downhole tools, or components thereof used in downhole drilling. Portions of drill bits or other downhole tools operate in high-stress environments and are prone to wear. Surfaces or portions of such drill bits and downhole tools can be made of materials with high strength and erosion resistance. Additive manufacturing can be used to form high-strength and erosion-resistant components. These components can be integrally formed with the downhole tool, attached to one or more surfaces, or otherwise applied to a downhole tool such as a drill bit.

[0030] According to embodiments of the present disclosure, a downhole tool can include any downhole tool, including drill bits, drill collars, reamers, mills, casing cutters, stabilizers, bicenter bits, etc. Although embodiments of the present disclosure may be described with reference to drill bits, it should be understood that the embodiments described herein can refer to any downhole tool.

[0031] Figure 1 An example of a drilling system 100 for drilling a surface formation 101 to form a wellbore 102 is shown. The drilling system 100 includes a rig 103 for rotating a drill string assembly 104 that extends downward into the wellbore 102. The drill string assembly 104 can include a drill string 105, a bottom hole assembly (“BHA”) 106, and a drill bit 110 attached to the lower end of the drill string 105.

[0032] The drill string 105 may include a number of joints of drill pipe 108 end - to - end connected by tool joints 109. The drill string 105 transmits drilling fluid through a central bore and rotational power from the rig 103 to the BHA 106. In some embodiments, the drill string 105 may also include additional components such as subs, pup joints, etc. The drill pipe 108 provides a hydraulic passage through which drilling fluid is pumped from the surface. The drilling fluid is discharged through selected - sized nozzles, orifices, or other apertures in the drill string 105 and the bit 110 for cooling the bit 110 and the cutting structures thereon and for lifting cuttings out of the wellbore as the wellbore 102 is drilled.

[0033] The BHA 106 may include a bit 110 or other components. An exemplary BHA 106 may include additional or other components (e.g., coupled between the drill string 105 and the bit 110). Examples of additional BHA components include drill collars, stabilizers, measurement - while - drilling (“MWD”) tools, logging - while - drilling (“LWD”) tools, downhole motors, underreamers, mill cutters, hydraulic breakers, jars, vibration or shock - absorbing tools, other components, or combinations of the foregoing. The BHA 106 may also include a rotary steerable system (RSS). The RSS may include directional drilling tools that change the direction of the bit 110, thereby changing the trajectory of the wellbore. At least a portion of the RSS may maintain a geostationary position relative to an absolute reference frame such as gravity, magnetic north, and / or true north. Using measurements obtained through the geostationary position, the RSS may position the bit 110, change the path of the bit 110, and guide the directional drilling tools on a desired trajectory.

[0034] Generally, the drilling system 100 may include other drilling components and accessories such as specialized valves (e.g., kelly cocks, blowout preventers, and safety valves). Additional components included in the drilling system 100 may be considered part of the drill tool assembly 104, the drill string 105, or the BHA 106, depending on their location within the drilling system 100.

[0035] The drill bit 110 in the BHA 106 can be any type of drill bit suitable for degrading downhole materials. For example, the drill bit 110 can be a drill bit suitable for drilling surface formations 101. An exemplary type of drill bit for drilling surface formations is a fixed cutter or drag bit. In other embodiments, the drill bit 110 can be a mill shoe for removing downhole metal, composite materials, elastomers, other materials, or combinations thereof. For example, the drill bit 110 can be used with a whipstock to mill into the casing 107 that surrounds the wellbore 102. The drill bit 110 can also be a flat mill shoe for milling away tools, plugs, cement, other materials, or combinations thereof within the wellbore 102. Chips or other drill cuttings formed by using the mill shoe can be transported to the surface or can be allowed to fall downhole.

[0036] In some embodiments, the drill bit 110 can include one or more cutting elements 116. As the drill bit 110 rotates, the cutting elements 116 can erode the formation 101, thereby advancing the wellbore 102. The cuttings, formation, drilling fluid, and other drilling elements can wear the drill bit 110 and / or the cutting elements 116. Hardfacing materials placed on the high-wear portions of the drill bit 110 can reduce wear of the drill bit 110. According to embodiments of the present disclosure, the hardfacing materials can include pre-sintered blade caps that at least partially surround at least one cutting element 116 of the drill bit 110. This can help reduce wear of the drill bit 110.

[0037] Figure 2 is a perspective view of the downhole end of a drill bit 210 according to some embodiments of the present disclosure. Figure 2 The drill bit 210 in is an example of a fixed cutting edge drill bit or drag bit and includes a drill bit body 212 and a plurality of blades 214 that extend radially and axially therefrom. One or more of the blades 214—and possibly each blade 214—have a plurality of cutting elements 216 attached thereto. In some embodiments, at least one of the cutting elements 216 has a planar cutting face. The planar cutting face can be used to shear downhole materials, and such cutting elements are considered shear cutting elements. In other embodiments, at least one of the cutting elements 216 has a non-planar cutting face. The non-planar cutting face shears, impacts / chisels, or otherwise damages downhole materials. Examples of non-planar cutting elements (i.e., cutting elements having non-planar cutting faces) include cutting elements having a conical, ridged, domed, saddle-shaped, chisel-shaped, spoon-shaped, or other non-planar cutting face.

[0038] The cutting elements 216 of the drill bit 210 may experience different wear rates in different regions of the drill bit body 212 or the blade 214. The cutting elements 216 of the drill bit 210 experience different wear rates at the tapered region 228, nose region 230, shoulder region 232, or gauge region 234 of the blade 214. For example, the cutting elements 216 in the nose region 230 may experience a higher wear rate than the cutting elements 216 in the gauge region 234. In other examples, the cutting elements 216 in the shoulder region 232 may experience a higher wear rate than the cutting elements 216 in the nose region 230.

[0039] Accordingly, the drill bit body 212, the blade 214, or a combination thereof may include one or more bulk materials, such as a steel or carbide matrix. As provided herein, the drill bit 210 includes a second material, i.e., the composite material of the present invention, which is harder and / or has higher wear resistance or erosion resistance than the bulk material.

[0040] Traditionally, hardfacing has been applied to steel drill bits to increase the wear resistance and / or erosion resistance of certain regions on the drill bit, such as the formation-facing surface of the blade and the gauge region. However, hardfacing has traditionally been a manual process of applying a molten material such as spray or rod. The molten material is applied to the drill bit, and then the material cools on the drill bit to form the final geometry. Since this is a manual process, hardfacing can be variable and subject to defects, resulting in premature failure of the hardfacing and / or the hardfaced component at or near the defect. For example, hardfacing may fail at the boundaries, composition changes, layers, or other inconsistencies of the hardfacing material. In other examples, hardfacing may peel off the downhole tool due to insufficient bond strength between the hardfacing material and the downhole tool and / or excessive residual stress. Additionally, the heat applied to the drill bit near the cutting tooth pockets by the hardfacing process may degrade the base steel body material, resulting in poor bond strength between the cutting elements 216 and the cutting tooth pockets.

[0041] According to one or more embodiments of the present disclosure, portions of the drill bit body 212, the blade 214, or both may be formed from a metal matrix composite (MMC). A preformed MMC segment may be joined to the drill bit body 212 or the blade 214 formed from a different material. For example, the MMC segment may be joined to a steel body drill bit. In another example, an MMC segment having a first composition may be joined to a matrix drill bit having a second composition.

[0042] Figure 3is a partially exploded side view of an embodiment of a drill bit 310 having segments 358 formed of MMC and attachable to a blade 314. The MMC of the present disclosure can form segments 358 attached to the blade 314 to form at least a portion of the blade, such as a front surface, an outer surface, a back surface, or any combination thereof. In some embodiments, the MMC segments 358 are disposed on one or more formation-facing surfaces of the drill bit 310. The MMC segments 358 can at least partially define, together with the blade 314, one or more cutting tooth pockets 338. Regardless of which component of the drill bit 310 forms the cutting tooth pockets 338, each cutting tooth pocket 338 can be configured to receive a corresponding cutting element 316 (e.g., a planar cutting element, a non-planar cutting element). For example, the blade 314 can form a portion of the base and side of the cutting tooth pocket 338-1, and the MMC segment 358 can at least partially form the side of the cutting tooth pocket 338-2. In some embodiments, the MMC segments 358 can completely define one or more cutting tooth pockets 338. The MMC segments 358 can be coupled to a recess 342 of the blade 314, where the recess 342 includes a back surface 344 and a side surface 346. The MMC segments 358 can be coupled to the blade 314 by brazing, mechanical fasteners, welding, or the like. As described in U.S. Patent 11,313,176, U.S. Patent Application 2020 / 0123858, and International Patent Application PCT / US2021 / 047731, which are incorporated herein by reference, the MMC segments 358 can be formed in various shapes for disposition with the drill bit 310.

[0043] Downhole tools, such as the drill bit 310, can employ MMC segments having improved strength and erosion / wear resistance. The disposition of the MMC segments on the bit body 312 and / or the blade 314 can combine the benefits of the bit body 312 being made of a first material (e.g., steel) with the benefits of the MMC as described herein. In some embodiments, the bit body material and / or the blade material is a material having lower erosion resistance and / or wear resistance than the MMC segment material. In other embodiments, the bit body material and / or the blade material is a material having higher toughness than the MMC segment material. In some examples, the bit body material and / or the blade material comprises a steel alloy, while the MMC segment material comprises a carbide (e.g., tungsten carbide). The steel alloy can have higher toughness than the relatively brittle tungsten carbide, and the carbide can provide greater wear resistance and / or erosion resistance during the cutting operation.

[0044] Typically, an MMC is a composite material formed from two or more components, where at least one of the components is a metal and one or more other components can be a metal or a non-metal, including a ceramic or an organic compound. Such other components may include a reinforcement material dispersed and embedded in a continuous metal matrix. The metal matrix may be formed from a binder material that is at least partially melted to bond with the reinforcement material. The reinforcement material can be hard particles that provide wear and erosion resistance to the continuous metal matrix. Examples of hard particles that can be used with the MMCs described herein include tungsten carbide, such as cast tungsten carbide (including spherical or angular particles), coarse-grained tungsten carbide, carburized tungsten carbide, sintered tungsten carbide particles, titanium carbide, silicon carbide, or combinations of the foregoing materials.

[0045] MMCs can be formed by various processes. A typical matrix drill body is an MMC formed by infiltrating a porous powder or component with a molten material (e.g., a metal binder). For example, a mold for the drill body can be formed and then filled with tungsten carbide powder. The powder can be infiltrated with a molten transition metal alloy to form the matrix drill body. Additive manufacturing (AM) can be used to form MMCs that make up the drill body or a part of the drill, such as segments that can be attached to the drill body. Example additive manufacturing processes include, but are not limited to, powder bed fusion, binder jetting, infiltration / casting, laser deposition, or cladding. Powder bed fusion techniques can include, for example, high-energy melting techniques, which include direct metal laser sintering (DMLS), electron beam melting (EBM), selective heat sintering (SHS), selective laser melting (SLM), and selective laser sintering (SLS). In one or more particular embodiments, an MMC can be formed layer by layer using EBM, where successive layers of a mixture of hard material and binder powder are deposited and the metal phase or binder is sintered or otherwise melted to form a dense solid composite. The MMC formed by EBM may be fully dense and thus no significant infiltration may occur or may not be possible subsequently.

[0046] In at least some embodiments, the materials of the present disclosure can be used to produce drill bits, other cutting tools, or downhole tools or components thereof in a manner that either cannot be achieved using other techniques (such as infiltration) or would result in products with physically very different properties. For example, when using small particle sizes in high-energy fusion manufacturing techniques such as EBM, a vacuum environment can be used. In the absence of a vacuum environment, due to weak capillary connections and unconnected voids, small particle sizes may not be able to infiltrate properly, resulting in restricted flow of the binder material. Additionally, at elevated infiltration temperatures, carbide or other hard particles may be damaged, so traditional infiltration is not advisable. For example, particularly for cast carbide and nickel, iron, or cobalt binders, infiltration at temperatures similar to those used in high-energy fusion techniques may produce an η-phase in the carbide, resulting in a decrease in transverse rupture strength and toughness and an increase in the brittleness of the material. Furthermore, high-energy fusion techniques can be used to deposit and fuse hard particles and binder materials in layers with relatively consistent weight and volume percentages of hard particles. In contrast, particularly for compositions with relatively low volume percentages of hard particles, infiltration techniques cause the hard particles to settle to the bottom of the mold, resulting in a significant gradient in the weight and volume percentage of hard particles in the drill bit, and thus a significantly smaller volume and mass of hard particles at the top of the molded part. Therefore, when produced layer by layer using high-energy fusion techniques, components formed from relatively low volumes of hard particles have physically different properties compared to those produced using infiltration or molding processes.

[0047] Additive manufacturing via EBM can form MMC segments designed with a 3D CAD model. The 3D CAD model can be printed in successive layers of powder material by an EBM machine. An EBM machine (such as the Arcam EBM Spectra H purchased from GE) can facilitate the printing of MMC segments that closely match the 3D CAD model. In some embodiments, the MMC segments can be printed with a minimum layer thickness of 0.05 mm, with a tolerance of ±0.4 mm. The MMC segments to be printed can be arranged in various orientations within the build space of an AM system (e.g., an EBM machine) to increase the packing density of the MMC segments within the build space. The MMC segments can be arranged within the build space of the AM system such that the MMC segments are fully supported and properly spaced during the printing process, such that the cured MMC segments are within the desired shape and dimensional tolerances of the corresponding 3D CAD model. In some embodiments, the AM system forms the MMC segments under a vacuum below ambient atmospheric pressure. In some embodiments, the AM system forms the MMC segments in an environment of an inert atmosphere. The vacuum and / or inert atmosphere used to form the MMC segments can inhibit oxidation reactions of the powder material.

[0048] Although the MMC segments described herein can be formed by various AM systems, the following table gives the specifications of an Arcam EBM SpectraH as a non-limiting example of parameters and environments that can be used with the powder mixtures described herein to form MMC segments:

[0049] Table 1

[0050] Maximum build size 250x 430mm (D, H) Maximum beam power 6kW Cathode type Single crystal Minimum chamber pressure 5x 10-4mbar Typical build atmosphere 4x10-3mbar (helium partial pressure) Power supply 3x 400V, 32A, 13kVA Helium consumption, build process 5 liters / hour Helium consumption, ventilation 150 - 200 liters / build Typical process temperature range 600-1,100℃ Dimensions 1,328x 2,344x 2,858mm (D, W, H) Weight 2,915kg CAD interface Standard STL

[0051] According to the present disclosure, MMCs produced by AM optionally use spherical-shaped particles. All or substantially all of the hard particles and the metal binder can be spherical-shaped particles. For example, the hard particles can be spherical cast tungsten carbide (SCC) particles. Spherical-shaped particles have good flowability and fillability. The term SCC can include carbide hard particles other than tungsten carbide, such as, but not limited to, titanium carbide (TiC) and silicon carbide (SiC). However, for some direct sintering processes using lasers or electron beams, the use of near-spherical particles can be contemplated, where the ratio of the equivalent diameters measured in the vertical position is between 0.7 and 1.0. The particles used can be individual hard particles or a mixture of hard particles and binder metal. The proportion of hard particles in the finished MMC can be equal to or greater than 27 vol%, 30 vol%, 36 vol%, 40 vol%, 50 vol%, 55 vol% or up to 60 vol%. The proportion of hard particles of tungsten carbide (e.g., spherical cast tungsten carbide) in the finished MMC can be about 40 wt%, 44 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt% or up to 80 wt% If the densities of the hard particles and the metal binder are significantly different, it can be expected that the hard particles and the alloy particles have similar weights. In this case, two different sizes of particles can be used - one for the hard particles and the other for the binder particles. Based on the thermal diffusivity value of a given direct energy sintering or melting process, the particle sizes of the hard material and the binder material may also be different.

[0052] As described herein, one or more embodiments of the present disclosure may use cast tungsten carbide in an MMC. Cast tungsten carbide may have an eutectic composition between approximately tungsten carbide binary alloy (W2C) and tungsten carbide (WC). Cast tungsten carbide can be made by resistively heating tungsten in contact with carbon. Types of available cast tungsten carbide include crushed cast tungsten carbide and spherical cast tungsten carbide. The process for producing spherical cast carbide particles is described in U.S. Pat. Nos. 4,723,996 and 5,089,182, which are incorporated herein by reference. Briefly, tungsten can be heated in a graphite crucible having holes, and the resulting eutectic mixture of W2C and WC can be dripped through the holes. This liquid can be quenched in an oil bath and subsequently crushed or ground to the desired particle size to form so-called crushed cast tungsten carbide. In other processes, a mixture of tungsten and carbon is heated above the melting point to form a continuously flowing fluid, which is then poured onto a rotating cooling surface, typically a water-cooled casting cone, pipe, or concave turntable. The molten stream is rapidly cooled on the rotating surface and forms spherical particles of eutectic tungsten carbide, called spherical cast tungsten carbide. The melting temperature of SCC is approximately 2525 °C.

[0053] The eutectic mixture of WC and W2C may contain about 4.5 wt% carbon. The cast tungsten carbide used as the matrix powder may have a hypoeutectic carbon content of about 4 wt%. Thus, by way of example only, the cast tungsten carbide used in the tungsten carbide mixture may contain 3.7 to 4.2 wt% carbon.

[0054] It is also contemplated that while one or more embodiments may have carbide particles (particularly spherical, exemplary embodiments) comprising or consisting of cast tungsten carbide, other embodiments may alternatively or also use other types of tungsten carbide, including for example, coarse-grained tungsten carbide, carburized tungsten carbide, or sintered tungsten carbide, sintered tungsten carbide, alone or in combination with each other and / or cast tungsten carbide. The various types of tungsten carbide materials described herein can be selected to provide a drill bit tailored for a specific drilling application. For example, the type (e.g., cast, hardened, sintered, or coarse-grained tungsten carbide), shape, and / or size of the carbide particles used to form the MMC may affect the material properties of the formed body, including fracture toughness, transverse rupture strength, and wear and erosion resistance.

[0055] The continuous metal matrix of the MMC can be formed from a metal binder material. The metal binder material can be present in the finished MMC in a proportion between 30 and 72.5 vol%. Suitable metals include any transition metal, main group metal, and their alloys. For example, nickel, iron, cobalt, titanium, or copper can be used as the main component. As discussed in detail below, the metal binder material of the sample material is a nickel-based binder with a silicon content greater than 6.5 wt%. For MMCs formed by the EBM process, the metal binder material is a powder or a powder mixture. One or more powders of the metal binder material for the EBM process can be spherical and can be formed by a process such as a gas atomization process. Silicon can alloy with the nickel in the binder powder or can be a powder component separate from the nickel in the binder powder. In some embodiments, the nickel-based binder does not contain boron. The silicon content can be increased to lower the melting temperature of the binder and reduce the dissolution of carbide particles therein during binder melting. The silicon content can be increased to increase the fluidity of the molten binder.

[0056] The hard particles and binders of MMCs have been studied to develop the desired compositions with improved wear resistance and strength described herein. Figure 4 and Figure 5 An optical micrograph of an exemplary MMC having the following composition is shown. Figure 4 The first sample 450 of is an MMC fabricated by EBM additive manufacturing that has hard particles 452 with a nominal size less than 50 microns within a nickel-based binder 454. The hard particles 452 are spherical cast tungsten carbide (SCC) particles. The hard particles 452 account for approximately 30 vol% of the MMC, with the binder 454 forming the remainder (70 vol%) of the MMC. The nickel-based binder 454 has silicon between 5.5 and 6.5 wt%, with nickel forming the remainder (93.5 to 94.5 wt%) of the binder 454. The distribution of the SCC particles within the first sample 450 is uniform, with an average free path of approximately 97 μm. Figure 5 The second sample 550 of is an MMC fabricated by EBM additive manufacturing that has hard particles 552 with a nominal size less than 50 microns within a nickel-based binder 554. The hard particles 552 are SCC particles. The hard particles 552 account for approximately 65 wt% (50 vol%) of the MMC, with the binder 554 forming the remainder (35 wt% / 50 vol%) of the MMC. The nickel-based binder 554 has 7 to 7.5 wt% of silicon, with nickel forming the remainder (92.5 to 93.0 wt%) of the binder 554. The distribution of the SCC particles within the second sample 550 is uniform, with an average free path of approximately 41 μm, which is approximately 42% of the average free path of the first sample 450.

[0057] Figure 6Figure 650 shows the transverse rupture strength (TRS) and erosion resistance coefficient of various materials, including traditional and new materials used in drill bits or downhole tools. As discussed herein, the TRS of a material has been determined by one or both of ASTM B528 and ASTM B406. The erosion resistance coefficient is the normalized result of a jet erosion test similar to ASTM G76, which measures the volume loss per unit of sand used to compare the erosion resistance performance of materials. For example, a modified ASTM G76 test can be used to determine the erosion rate, where water (instead of air) is used as the fluid. The sand particles are 50 / 70 mesh Ottawa sand, and the test time is 6 to 12 minutes. The fluid and entrained sand particles are directed at the test material at an angle of 150°. The distance between the nozzle outlet and the test material is 2 inches (5.08 cm). The jet velocity is approximately 200 feet per second (61 m / s), and the sand consumption is approximately 0.75 lb / min (0.34 kg / min). The erosion rate value of the test material is normalized by the weight of the sand used to determine the erosion resistance coefficient. The erosion resistance coefficient is a normalized value that is inversely proportional to the measured erosion rate.

[0058] The traditional materials T1 and T2 are infiltrated matrix materials. For example, T1 is an infiltrated matrix material that has a mixture of fine tungsten carbide and crushed tungsten carbide, infiltrated with a copper-based binder containing manganese, nickel, and zinc. T2 is an infiltrated matrix material that has coarsely crushed tungsten carbide (80 / 120 mesh), infiltrated with the same copper-based binder. T3 is a hardfacing material that can be applied to the drill bit by a welding process such as oxyacetylene spraying. T3 may have rough spherical tungsten carbide (210 - 400 μm) and a binder of nickel, chromium, iron, silicon, and boron. The TRS of the traditional materials T1 - T3 is less than or equal to 155 ksi, and the erosion resistance coefficient is less than 14.

[0059] Compared with traditional materials, additive manufacturing materials with higher TRS and erosion resistance coefficient have been developed. The TRS is related to the strength of the material and the ability to operate without failure in a downhole environment. The erosion resistance coefficient is related to the ability to maintain the tooth groove structure around the cutting element. The additively manufactured MMC is formed by EBM and includes hard particles and a metal binder, the composition of which is as described in Table 2 below:

[0060] Table 2

[0061]

[0062]

[0063] As Figure 6As shown, materials A1-A5 exhibit TRS greater than 200 ksi and greater than conventional materials T1-T3. Increasing the silicon content of the binder is associated with improved TRS and erosion resistance. Increasing the hard particle content is also associated with improved erosion resistance and reduced TRS. Interestingly, increasing the silicon content of the binder by about 7.5wt% with A5 appears to unexpectedly increase the TRS, which is 30% greater than the A3 material with 5.5-6.5wt% silicon at the same hard particle content, and the A5 material has a TRS that is 20% greater than the A4 material with a greater hard particle content but the same binder. In addition, the erosion resistance coefficient of the A5 material is 50% greater than the erosion resistance coefficient of the A3 material with less silicon in the binder.

[0064] Figure 7 is a graph showing the results of further TRS testing of materials T1, T2, T3, A1, A2, A3, A4 and A5 having different amounts of hard particles mixed with a metal binder. Figure 6 As shown in the sample, the TRS of traditional materials T1-T3 is less than or equal to 155ksi. The TRS of AM MMC A1-A3, A4 and A5 is greater than 200ksi. Figure 6 samples shown. However, the TRS of A5: 326 ksi is greater than the TRS of A4: 270 ksi. The A5 MMC was formed by EBM with 44 wt% SCC hard particles (30 vol%) and 56 wt% nickel-based binder (with a silicon content between 7-7.5 wt%), and the A4 MMC was formed by EBM with 65 wt% (50 vol%) SCC hard particles and 35 wt% nickel-based binder (with a silicon content between 7-7.5 wt%). Although increasing the hard particle content in the MMC is expected to improve the erosion resistance factor, it is better to improve both the erosion resistance factor and the TRS at the same time. The TRS of A5 is unexpectedly about 20% greater than that of A4, which has fewer hard particles in the same binder. In addition, the TRS of A5 is more than twice that of conventional materials T1-T3.

[0065] Figure 8 A scanning electron microscope image 850 of an A1 MMC with a nickel-based binder containing silicon and boron is shown. The hard particles 852 in image 850 show a smooth rounded surface 853 corresponding to a cross section of the SCC hard particles 852. The binder 854 in image 850 exhibits a uniform color, indicating a uniform composition after printing the A1 MMC. The melting point of the nickel-based binder containing silicon and boron is approximately 1043°C.

[0066] Figure 9Shows a scanning electron microscope image 950 of an A5 MMC with a nickel-based binder containing silicon but no boron. The hard particles 952 in image 950 show an irregular circular surface or reaction zone 953 between the hard particles 952 and the binder 954. The reaction zone 953 may be formed at least in part due to the softening or melting of the hard particles 952 during the EBM process. In addition, the binder 954 in image 950 shows uneven coloring in various color shapes between the SCC hard particles 952. The binder 954 of the A5 MMC shows a dispersed dispersion 956 between the hard particles 952. The dispersion 956 is considered to be a precipitate of WC or W2C dissociated from the hard particles 952 and / or a tungsten-rich η-phase and / or a nickel-rich η-phase within the binder 954. The dispersion 956 has greater strength and hardness than the binder 954 itself. The dispersion 956 is smaller than the hard particles 952 but is also used to improve the strength, hardness, and wear resistance of the A5 MMC material. That is, the distribution of the dispersion 956 and the hard particles 952 throughout the binder 954 increases the hardness of the binder and improves the wear resistance of the A5 MMC material. The dispersion 956 reduces the mean free path through the binder 954 of the MMC. The dispersion 956 can be formed to have dimensions between 2 and 20 μm, between 5 and 15 μm, or up to 10 μm in at least one dimension. The dispersion 956 can fill a certain range of the volume percentage of the binder 954, such as a binder volume greater than 2%, between 5% and 30%, between 10% and 25%, or between 15% and 20%.

[0067] In addition, the bonding ratio of the reaction zone 953 of the A5 MMC material between the hard particles 952 and the binder Figure 8 is stronger than the bonding between the hard particles 852 and the binder of the A1 MMC material shown. Therefore, the reaction zone 953 and the dispersion 956 of the A5 MMC material shown in image 950 increase the strength and wear resistance of the A5 MMC. The melting point of the nickel-based binder of the A5 MMC material with a silicon content > 6.5 wt% is approximately 1250 °C. Due to the relatively high temperature of the EBM process, the higher melting temperature of the A5 MMC material may contribute to the formation of the reaction zone 953 and the dispersion 956.

[0068] Figure 10 is a scanning electron microscope image 1050 of the fracture surface of an A2 MMC. As described above, the A2 MMC has 44 wt% SCC hard particles (30 vol%) and a nickel-based binder containing silicon and boron. Some of the hard particles 1052 in image 1050 show transgranular fracture 1055. In addition, the fracture surface of the binder 1054 is consistent with brittle fracture due to the sharp edges on the surface of the binder. In sharp contrast to this, Figure 11It is a scanning electron microscope image 1150 of the fracture surface of A3 MMC. As described above, A3 MMC has 44 wt% of SCC hard particles (30 vol%) 1152 and a nickel-based binder 1154 that contains no boron and has a silicon content between 5.5 - 6.5 wt%. The fracture surface in image 1150 shows a transgranular fracture 1155 through the hard particles. The fracture surface of the binder 1154 shows a pit feature 1157, which is consistent with the ductile fracture of the binder 1154. In addition, the fracture surface 1154 of the binder 1154 is rougher than the fracture surface of the binder 1054. Therefore, the binder 1154 of A3 MMC seems to be able to absorb more stress until failure than the binder 1054 of A2 MMC that contains boron and less silicon.

[0069] Figure 12 The graph 1250 shows the TRS of multiple MMC samples with binders having different silicon contents. The TRS of the A1 MMC sample with 44 wt% SCC (30 vol%) and a nickel-based binder containing silicon and boron is 205 ksi. Relative to the A1 MMC sample, the second sample 1252 removes boron and adjusts the silicon in the nickel-based binder to 3.5 wt% of the binder. As a result, the TRS of the second sample 1252 increases to 287 ksi. The third sample 1254 further increases the silicon in the nickel-based binder to 7.5 wt% of the binder, which increases the TRS of the third sample 1254 to 326 ksi. However, increasing the silicon in the nickel-based binder to 12.5 wt% of the binder reduces the TRS of the fourth sample 1256 to 260 ksi, which is less than the TRS of the second sample 1252 with 3.5 wt% silicon in the binder.

[0070] The results of additional MMC samples 1258 and 1260 with 65 wt% SCC (50 vol%) are shown in Chart 1250. The fifth sample 1258 with 65 wt% SCC (50 vol%) and a nickel-based binder with a silicon content of 3.5 wt% was tested at a TRS of 268 ksi, which is less than the TRS of the second sample 1252 with the same binder composition. The sixth sample 1260 with 65 wt% SCC and a nickel-based binder with a silicon content of 7.5 wt% was tested at a TRS of 268 ksi, which is less than the TRS of the third sample 1254 with the same binder composition. Additionally, a seventh sample with 65 wt% SCC and a nickel-based binder with a silicon content of 12.5 wt% was produced, but the additively manufactured MMC sample cracked and could not be tested. Thus, having too much silicon in the binder is incompatible with a large amount of tungsten carbide in the MMC. That is, the MMC material with 65 wt% SCC (50 vol%) and a nickel-based binder with a silicon content of 12.5 wt% does not have enough ductility to facilitate the formation of a testable MMC sample.

[0071] As shown above, increasing the silicon in the nickel-based binder to 7.5 wt% can increase the TRS of the MMC formed by the EBM process. However, the effect of the silicon content in the binder on the microhardness of the binder is different from its effect on the TRS. Figure 13 Chart 1350 shows the Knoop microhardness 1352 of various binders with different compositions according to ASTM E384. The microhardness of the first binder containing 94 - 95 wt% nickel, 3.5 - 4.0 wt% silicon, and 1.5 - 2.0 wt% boron is 465. The microhardness of the second binder 1354 containing 96.5 wt% nickel and 3.5 wt% silicon without boron is 250. That is, removing boron alone seems to reduce the microhardness of the binder. For the third binder 1356 containing 94 wt% nickel and 6 wt% silicon, increasing the silicon only increases the microhardness of the binder by 6.6% to 266. For the fourth binder 1358 containing 92.5 wt% nickel and 7.5 wt% silicon, further increasing the silicon can increase the microhardness of the binder by 11% to 297. However, for the fifth binder 1360 containing 87.5 wt% nickel and 12.5 wt% silicon, increasing the silicon increases the microhardness of the binder by 285%. Thus, when optimizing the microhardness of the binder by adding only silicon, a binder composition with a silicon content greater than 7.5 wt%, even a binder composition containing boron, will be preferred.

[0072] It is desirable to increase the erosion resistance coefficient of the materials used in drill bits and drilling tools. Figure 14Figure 1450 shows a graph 1452 of the erosion resistance coefficients of MMC materials with the above different binder compositions. It is well known that increasing the hard particles in the mixture can improve the erosion resistance coefficient, but too many hard particles in the mixture may lead to brittleness. The erosion resistance coefficient of the first sample 1454 with a binder containing 94 - 95 wt% nickel, 3.5 - 4.0 wt% silicon, and 1.5 - 2.0 wt% boron is 16.8. The erosion resistance coefficient of the second sample 1456 with a second binder containing 96.5 wt% nickel and 3.5 wt% silicon and no boron is 24.8. Therefore, removing boron can improve the erosion resistance coefficient. The third sample 1458 with a third binder containing 94 wt% nickel and 6 wt% silicon increases the erosion resistance coefficient by 4% to 25.7. The fourth sample 1460 with a fourth binder containing 92.5 wt% nickel and 7.5 wt% silicon increases the erosion resistance coefficient by 42% to 36.6. The fifth sample 1462 with a fifth binder containing 87.5 wt% nickel and 12.5 wt% silicon increases the erosion resistance coefficient by 4% to 38. Therefore, by increasing the silicon content in the binder to about 7.5 wt%, there are significant and unexpected benefits to the erosion resistance coefficient, but further increasing the silicon content in the binder does not seem to significantly affect the erosion resistance coefficient.

[0073] As discussed herein, MMCs with nickel-based metal binder powders having a silicon content between 6.0 wt% and 12.5 wt% have been developed, with improved strength and erosion resistance. Hard particles such as SCC, TiC, or SiC can form 27 - 60 vol% of the MMC. For example, SCC hard particles can form 40 - 70 wt% of the MMC. Nickel-based binders containing silicon but no boron can facilitate high-temperature printing of the MMC, enabling the formation of a reaction zone around the hard particles of the MMC, which is thought to improve the strength of the MMC. Higher temperatures can help form a dispersion of hard particles in the molten binder to improve the strength and wear resistance of the MMC. Additionally, or as an alternative, during printing of the MMC, higher temperatures for nickel-based binders with a silicon content exceeding 6.5 wt% may generate precipitates of the binder (e.g., nickel-rich η phase and tungsten-rich η phase), thus improving the strength and wear resistance of the MMC. Additionally, MMCs with nickel-based binder powders having a silicon content close to 12.5 wt% seem to exhibit brittleness, but their erosion resistance is not significantly improved compared to MMCs with nickel-based binder powders having a silicon content between 6.0 wt% and 10.0 wt%. Compared to other metal binder powders currently available, MMCs using nickel-based metal binder powders with a silicon content between 6.0 and 10.0 wt% exhibit higher strength and erosion resistance required for use with downhole tools.

[0074] This document describes one or more specific embodiments of the present disclosure. These described embodiments are examples of the presently disclosed technology. Additionally, in order to provide a brief description of these embodiments, not all features of an actual implementation may be described in the specification. It should be understood that numerous implementation-specific decisions will be made in developing any such actual implementation in any engineering or design project to achieve the developer's specific goals, such as meeting system-related and business-related constraints, which may vary between different implementations. Furthermore, it should be understood that such development work may be complex and time-consuming, but it will still be a routine task in design, fabrication, and manufacturing for those of ordinary skill in the art who benefit from the present disclosure.

[0075] Additionally, it should be understood that references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be construed as excluding the existence of additional embodiments that also incorporate the recited features. For example, any element described with respect to an embodiment herein can be combined with any element of any other embodiment described herein. As will be appreciated by those of ordinary skill in the art as covered by the embodiments of the present disclosure, the numbers, percentages, ratios, or other values recited herein are intended to include the recited value, and also other values that are "about" or "approximately" the recited value. Accordingly, the recited values should be interpreted broadly enough to encompass at least values that are sufficiently close to the recited value to perform the desired function or achieve the desired result. The values include at least the variations expected in a suitable manufacturing or production process, and can include values within 5%, 1%, 0.1%, or 0.01% of the recited value.

[0076] In view of the present disclosure, those of ordinary skill in the art should recognize that equivalent constructions do not depart from the spirit and scope of the present disclosure, and various changes, substitutions, and alterations can be made to the embodiments disclosed herein without departing from the spirit and scope of the present disclosure. Equivalent constructions (including functional "means-plus-function" clauses) are intended to cover structures described herein as performing the recited function, including structural equivalents that operate in the same manner and equivalent structures that provide the same function. The applicant's express intent is not to invoke means-plus-function or other functional limitations for any claim, except for those claims in which the words "means for" appear in conjunction with the associated function. Every addition, deletion, and modification to an embodiment that falls within the meaning and scope of the claims will be embraced by the claims.

[0077] As used herein, the terms "about," "approximately," and "substantially" denote a quantity close to the stated amount within the standard manufacturing or process tolerances or still performing the desired function or achieving the desired result. For example, the terms "about," "approximately," and "substantially" may refer to a quantity within less than 5% of the stated amount, less than 1% of the stated amount, less than 0.1% of the stated amount, and less than 0.01% of the stated amount. Additionally, it should be understood that any direction or frame of reference in the foregoing description is only a relative direction or movement. For example, any reference to "up" and "down" or "above" or "below" only describes the relative position or movement of the relevant elements.

[0078] Without departing from the spirit or characteristics of the present disclosure, the present disclosure may be embodied in other specific forms. The described embodiments should be considered illustrative rather than restrictive. Therefore, the scope of the present disclosure is indicated by the appended claims rather than by the foregoing description. Changes within the meaning and scope of the equivalent forms of the claims will be included within the scope of the claims.

Claims

1. An additive manufactured metal matrix composite (MMC) comprising: Hard particles, which account for a proportion of the MMC greater than 27 vol%, wherein the hard particles are spherical in shape; and A binder comprising nickel and silicon, wherein the binder accounts for a proportion of the MMC less than 73 vol%, and wherein the silicon accounts for a proportion of the binder higher than 6.0 wt% but less than 12.5 wt% of the binder.

2. The MMC according to claim 1, wherein the transverse rupture strength (TRS) of the MMC is greater than 300 ksi, and the corrosion resistance coefficient is greater than 30.

3. The MMC according to claim 1, comprising a plurality of layers, wherein each layer of the plurality of layers comprises the hard particles dispersed throughout the binder, and each layer is formed in an additive manner adjacent to another layer of the plurality of layers.

4. The MMC according to claim 1, wherein the hard particles comprise spherical cast tungsten carbide.

5. The MMC according to claim 1, wherein the hard particles account for a proportion of the MMC between 30 vol% and 37 vol%, and the silicon accounts for a proportion of the binder between 7.0 wt% and 8.0 wt%.

6. The MMC according to claim 1, wherein the hard particles account for a proportion of the MMC greater than or equal to 50 vol%.

7. The MMC according to claim 1, wherein the binder consists essentially of nickel and silicon, and the silicon accounts for a proportion of the binder between 6.5 wt% and 9.0 wt%.

8. The MMC according to claim 1, wherein the silicon accounts for a proportion of the binder between 6.5 wt% and 9.0 wt%.

9. The MMC according to claim 1, wherein the hard particles comprise titanium carbide, silicon carbide, or any combination thereof.

10. The MMC according to claim 1, comprising a dispersion dispersed throughout the binder, wherein the dispersion has a length in the range of 5 to 15 μm, and wherein the dispersion comprises a nickel-rich η phase of the binder, a precipitate of the hard particles, or any combination thereof.

11. The MMC according to claim 1, comprising a dispersion dispersed throughout the binder, wherein the volume percentage of the binder filled by the dispersion is between 10% and 25% of the volume of the binder.

12. An additive manufactured metal matrix composite (MMC) comprising: Printing a first layer of the MMC; Printing a second layer of the MMC at least partially on the first layer, wherein each layer of the MMC comprises a mixture of hard particles and binder powder, wherein the hard particles account for a proportion of the MMC between 30 vol% and 50 vol%, and the binder powder comprises nickel and silicon, and the silicon accounts for a proportion of the binder powder higher than 6.0 wt%, but less than 10.0 wt% of the binder powder.

13. The additive manufacturing of the MMC according to claim 12, wherein printing the first layer of the MMC and printing the second layer of the MMC comprises using an electron beam melting system.

14. The additively manufactured MMC as claimed in claim 12, comprising a dispersion formed throughout the first layer and the second layer, wherein the dispersion has a length in the range of 5 to 15 μm, and wherein the dispersion comprises a nickel-rich η-phase of the binder powder, a precipitate of the hard particles, or any combination thereof.

15. The additively manufactured MMC as claimed in claim 12, wherein the hard particles comprise spherical cast tungsten carbide.

16. The additively manufactured MMC as claimed in claim 12, wherein the binder powder consists essentially of nickel and silicon, and the proportion of silicon in the binder powder is between 7.0 wt% and 9.0 wt%.

17. A drilling tool comprising a metal matrix composite (MMC) manufactured by additive manufacturing, the MMC comprising: Hard particles, which account for more than 44 wt% of the MMC, wherein the hard particles comprise spherical cast tungsten carbide particles; and A binder comprising nickel and silicon, wherein the binder accounts for less than 56 wt% of the MMC, and the proportion of silicon in the binder is higher than 7.0 wt% but lower than 10.0 wt% of the binder.

18. The drilling tool as claimed in claim 17, wherein the TRS of the MMC is greater than 300 ksi and the corrosion resistance coefficient is greater than 30.

19. The drilling tool as claimed in claim 18, wherein the proportion of the hard particles in the MMC is less than 50 wt%, and the proportion of silicon in the binder is between 7.5 wt% and 8.0 wt%.

20. The drilling tool as claimed in claim 17, wherein the binder does not contain boron.

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