JP2015508383A - Thermally stable polycrystalline cemented carbide material reinforced with fibrous material - Google Patents

Abstract

The polycrystalline diamond structure comprises a diamond body having a thermally stable diamond base material including bonded diamond crystals, and a plurality of fibers extending between the thermally stable diamond base material. And the diamond matrix comprises a diamond volume content of at least 99%. The diamond structure may be bonded to the substrate to form a shear cutter. The shearing cutter may be mounted on the bit body. [Selection] Figure 2

Description

  The present invention relates to a thermally stable cemented carbide material, and more particularly to a thermally stable polycrystalline cemented carbide material reinforced with a fibrous material to improve toughness. And further relates to a method of forming it. Polycrystalline diamond materials are known for their good wear resistance and hardness and are often used in cutting and rock drilling tools. To form polycrystalline diamond, diamond particles are sintered at high pressure and high temperature (HPHT sintering) to produce a superhard polycrystalline structure. In order to promote intergrowth of diamond crystals during HPHT sintering, a catalyst material, such as cobalt or another metal, is added to the diamond particle mixture prior to sintering and / or the diamond particle mixture is infiltrated during sintering. A polycrystalline diamond (PCD) structure is formed. The metals conventionally used as catalysts are selected from the group of solvent metal catalysts selected from Group VIII of the Periodic Table, including cobalt, iron, and nickel, and combinations thereof and alloys thereof. After HPHT sintering, the resulting PCD structure contains interconnected networks of diamond crystals, or grains bonded to each other, and the catalyst material occupies interstitial spaces, i.e. the gaps of the bonded diamond crystals. . The diamond particle mixture may be HPHT sintered in the presence of the substrate to form a PCD that is closely bonded to the substrate. The substrate may also act as a source of metal catalyst that penetrates into the diamond particle mixture during sintering.

  The amount of catalyst material used to form the PCD body represents a compromise between the desired properties of strength, toughness, and impact resistance, and hardness, wear resistance, and thermal stability. is there. Higher metal catalyst content generally increases the strength, toughness, and impact resistance of the resulting PCD body, while this higher metal catalyst content not only provides thermal stability, but also hardness and wear resistance of the PCD body. Also decreases. This trade-off results in the desired level of hardness, wear resistance, thermal stability, strength, impact resistance, and in particular applications, such as cutting and / or wear parts repair requirements for underground drilling rigs, and It has become difficult to provide PCD with toughness.

  Thermal stability can be particularly significant during wear or cutting operations. Conventional PCD bodies can be vulnerable to thermal degradation when exposed to high temperatures during cutting and / or wear applications. This vulnerability is the result of the difference that exists between the thermal expansion properties of the solvent metal catalyst placed between the lattices in the PCD and the intercrystalline bonded diamond. This difference in thermal expansion is known to start from a low temperature of 400 ° C. and can induce thermal stress, which is detrimental to the intercrystal bonding of diamond and eventually causes crack formation. As a result, this makes the PCD structure vulnerable to destruction. Such behavior is therefore undesirable.

  Another form of thermal degradation known to be associated with conventional PCD materials is related to the presence of solvent metal catalyst in the interstitial region of the PCD body and the adhesion of the solvent metal catalyst to diamond crystals. To do. Specifically, solvent metal catalysts cause undesired catalyzed phase transformations in diamond (converting diamond to carbon monoxide, carbon dioxide, or graphite) as the temperature is raised, thereby It is known that the temperature at which PCD bodies may be used is limited.

  To improve the thermal stability of the PCD material, the catalyst material may be removed from the PCD body after sintering. To form this thermally stable PCD material (sometimes referred to as TSP), diamond particles are first HPHT sintered in the presence of a solvent metal catalyst and the catalyst is interstitial between the diamond crystals. A PCD body occupying the region is formed. Thereafter, the catalyst material is removed from the PCD body, leaving a network of empty interstitial spaces between the diamond crystals. For example, one known approach is to remove a substantial portion of the catalyst material from at least a portion of the sintered PCD by subjecting the sintered PCD structure to an elution step. A thermally stable material part free of catalytic material is formed. If a substrate is used during HPHT sintering, the substrate is often removed prior to elution.

  In order to provide a thermally more stable carbide diamond body, polycrystalline diamond without binder is formed by converting graphite directly to diamond at ultra-high pressures and temperatures without the use of catalytic materials. . The resulting diamond material has a uniform intercrystalline diamond microstructure, with no catalyst material spaced between the diamond crystals. As a result, a diamond body without a binder does not suffer from thermal expansion differences between the diamond and the catalyst.

  However, this unbonded diamond body is expected to exhibit low fracture toughness while having high hardness and wear resistance at high temperatures, and this material is brittle and is prone to crushing, crack formation, and fracture in use. It becomes a thing.

  Accordingly, there remains a need for a cutting part that incorporates a thermally stable carbide diamond body to obtain not only wear resistance but also toughness at high temperatures.

  The provision of this summary introduces various concepts described further below in the detailed description. It is not intended that this summary identify fundamentally important or essential features of the claimed subject matter, and that this summary will be used to help limit the scope of the claimed subject matter. Also not intended.

  The present disclosure relates to a thermally stable cemented carbide material, and more specifically to a thermally stable polycrystalline cemented carbide material reinforced with a fibrous material for improved toughness, and a method of forming the same. To do. In one embodiment, the polycrystalline diamond structure comprises a thermally stable diamond matrix formed at ultra high temperature and pressure without the use of a catalytic material. In one embodiment, the pressure is between about 100-160 kbar, for example about 150 kbar, and the temperature is about 1800-2500 ° C. This thermally stable diamond matrix contains a network of diamond crystals that are bonded together and there is virtually no interstitial space between the diamond crystals. Spaced through the thermally stable diamond matrix is a network of fibers or fibrous materials that extend in a desired or irregular orientation through the diamond matrix. The provision of these fibers reinforces the diamond matrix, increases toughness and ductility, and prevents crack growth through the material. By preventing or slowing the propagation of cracks throughout the diamond matrix, the fibers prevent initial failure and work with this diamond structure can be continued. In one embodiment, a fiber reinforced thermally stable diamond matrix is incorporated into a cutting part, such as a shear cutter. According to another embodiment, a method of forming a fiber reinforced thermally stable diamond matrix is also provided.

  In one embodiment, a polycrystalline diamond structure is a thermally stable having a bonded-together crystal and a plurality of fibers extending between a thermally stable diamond matrix. Includes diamond body with diamond matrix. The diamond matrix includes a diamond volume content of at least 99%.

  In one embodiment, a method of forming a fiber reinforced thermally stable polycrystalline diamond structure includes providing a fiber matrix, infiltrating graphite into the fiber matrix, and graphite and fiber matrix. And HPHT sintering without catalyst material at ultra high temperature and pressure.

  In one embodiment, a polycrystalline diamond structure comprises a diamond body with a single bonded diamond crystal, a diamond matrix having interstitial spaces between the diamond crystals, and a carbonate catalyst disposed in the interstitial space. As well as a plurality of fibers extending between the diamond matrix.

FIG. 4 illustrates a schematic diagram of a microstructure of a thermally stable diamond matrix material according to an example embodiment. FIG. 2 illustrates a perspective view of a diamond body incorporating the microstructure of the material of FIG. FIG. 3 illustrates a partial cross-sectional view of a thermally stable diamond matrix that includes a fibrous material, according to an example embodiment. FIG. 4 illustrates a flow diagram of a method for forming a thermally stable diamond matrix, according to an example embodiment. FIG. 3 illustrates a perspective view of a cutting part incorporating a thermally stable diamond matrix, according to an example embodiment. 6 illustrates a perspective view of a drag bit incorporating the cutting part of FIG. FIG. 7a shows a top view and FIG. 7b illustrates a side view of a fiber preform. FIG. 3 illustrates a partial cross-sectional view of a pre-sintered carbonate diamond powder having a laminated fiber layer according to an example embodiment.

DETAILED DESCRIPTION The present disclosure relates to thermally stable cemented carbide materials, and more specifically, thermally stable polycrystalline cemented carbide materials reinforced with fibrous materials for improved toughness, and formation thereof Related to the method. In one embodiment, the polycrystalline diamond structure includes a thermally stable diamond matrix formed without using a catalytic material at ultra high temperatures and pressures. In one embodiment, the pressure is between about 100-160 kbar, for example about 150 kbar, and the temperature is about 1800-2500 ° C. This thermally stable diamond matrix includes a network of diamond crystals bonded together and having substantially no interstitial space between the diamond crystals. Spaced through the thermally stable diamond matrix is a network of fibers or fibrous materials that exist in a desired or irregular orientation through the diamond matrix. The provision of these fibers reinforces the diamond matrix, increases toughness and ductility, and prevents crack growth through the material. By preventing the propagation of cracks throughout the diamond matrix, the fiber prevents initial failure and allows the diamond structure to continue working. In one embodiment, a fiber reinforced thermally stable diamond matrix is incorporated into a cutting part, such as a shear cutter. According to another embodiment, a method of forming a fiber reinforced thermally stable diamond matrix is also provided.

  For clarity, as used herein, the term “PCD” is a conventional polycrystalline diamond formed using a metal solvent catalyst during the HPHT sintering process, and the interstitial space, ie This refers to a material that forms a fine structure of bonded diamond crystals in which a gap between the bonded diamond crystals is occupied by a catalyst material. “Thermal stable PCD” (ie, TSP) is a PCD material that has been subsequently processed to substantially remove catalyst material from at least a portion of the PCD body, eg, the entire PCD body after HPHT sintering. Alternatively, the catalyst material is removed from the interstitial region of the PCD body by eluting a part thereof. As described further below, embodiments herein provide a “thermally stable diamond matrix” formed without the use of a metal catalyst. This diamond material is referred to as “thermally stable diamond matrix” and not “PCD” in order to clarify that no metal solvent catalyst is used. This is for distinguishing from thermally stable PCD (TSP) formed by performing HPHT sintering using NO and removing the catalyst after sintering. Despite not being formed using a catalyst, this thermally stable diamond matrix has a polycrystalline microstructure, as described in more detail below.

  As described below, the embodiments herein provide a thermally stable diamond matrix through a process that does not use a metal catalyst material. This thermally stable diamond material is also referred to as “no binder” diamond material. A schematic of a region of the thermally stable diamond matrix 10 is illustrated in FIG. 1 according to an embodiment of the present disclosure. The thermally stable diamond base material 10 has a polycrystalline microstructure that includes a plurality of diamond crystal grains or crystals 12 bonded together. As shown in FIG. 1, the microstructure of this material is such that there are substantially no gaps or interstitial spaces between the diamond crystals 12. The diamond crystals 12 are directly bonded to each other. The thermally stable diamond base material 10 is substantially pure carbon, and its diamond volume fraction is substantially 100%. There is no binder phase or catalyst material between the diamond crystals 12. This material is described as being “substantially” free of interstitial and interstitial spaces and is described as being “substantially” 100% diamond, which is a slight imperfection within the diamond matrix 10. This is to allow for the possibility of leaving small voids or spaces between portions of the diamond crystal due to potentiality and misalignment. In one embodiment, the microstructure of the thermally stable diamond matrix material has a diamond volume content of at least 99%, and in another embodiment at least or about 99.5%, and in another embodiment. At least or about 99.8%, and in another embodiment at least or about 99.9%. In one embodiment, the diamond matrix 10 has a fine diamond crystal grain size, eg, an average diamond crystal grain size of about 50 nm or less.

  This diamond matrix 10 is inherently thermally stable due to the uniform diamond content. There is no thermal expansion difference between the different phases of this material. As a result, the diamond body formed from this thermally stable diamond matrix 10 is very high even at high temperatures where conventional PCD suffers from thermal degradation due to differential expansion of the diamond and catalyst phases. It is possible to indicate strength.

  A polycrystalline diamond structure in the form of a cylindrical diamond body 14 is shown in FIG. The diamond body 14 is formed from the thermally stable diamond base material 10 of FIG. The diamond body 14 includes a cutting edge 16 composed of the high-strength and thermally stable diamond base material 10.

  A diamond body composed entirely of the material shown in FIG. 1 should provide high strength and wear resistance, but is also expected to suffer a reduction in fracture toughness, which is substantially 100% diamond volume. This is due to the material composition having a uniform content. This reduction in fracture toughness is due in part to the fine grain size of the diamond matrix, and diamond materials with very fine grain size reduce the fracture toughness, eg, about 3 in fracture toughness testing. It is known to exhibit ˜5 MPa√m (“MPa square root meter). The result is a brittle material that is vulnerable to crushing, crack formation, and failure.

  Accordingly, a thermally stable diamond matrix is reinforced with fibrous material in accordance with the disclosed embodiments. A cross-sectional view of a fiber reinforced thermally stable diamond structure 100 is shown in FIG. Diamond structure 100 includes a thermally stable diamond matrix 110 on which fibers 120 are spaced apart. The thermally stable diamond matrix 110 includes diamond crystals that are directly bonded to each other and has the microstructure of the material shown in FIG. The diamond base material 110 is formed without using a catalyst material, and a method for forming this material will be further described below. As shown in FIG. 3, one or more fibers 120 extend through the diamond matrix 110 and traverse the diamond structure 100 between bonded diamond crystals.

  This fiber reinforced thermally stable diamond structure 100 is expected to exhibit improved toughness and impact resistance due to the presence of the fibers 120. As a result, in the diamond structure 100, toughness and spreadability are increased. For example, as shown in FIG. 3, cracks 115 can form in the cemented carbide matrix 110 during operation, and the cracks can propagate across the diamond matrix 110 to separate bonded diamond crystals. There is sex. Without any fiber reinforcement, this crack can grow and spread across the diamond structure, potentially breaking apart the diamond matrix. For example, if such a diamond structure (without any fiber reinforcement) is incorporated into a cutting part, such as a diamond body on a shear cutter, crack growth across the diamond body can cause initial failure of the cutting part There is sex.

  However, the fiber 120 counters the failure mode by preventing the growth of cracks across the diamond matrix 110. As shown in FIG. 3, the crack 115 extends from the edge of the diamond structure 100 and reaches the fiber 120A. This fiber prevents (or inhibits) the crack 115 from extending further through the material. Fibers have greater ductility and longer strain to failure than diamond, which means they can stretch and deform more than diamond without cracks. This fiber can withstand physical displacement due to deformation, and thus can absorb the stress applied by the crack. In a diamond base material, a crack causes a load on the diamond base material at the tip of the crack, causing the diamond base material to break and break up, further growing the crack, and the load is released on the newly cracked area. And a new load is applied to the new tip of the crack. Once the crack reaches the fiber 120A, the fiber 120A absorbs this load applied to the crack tip and there is no load release or crack extension. As a result, crack growth may slow down at fiber 120A and not grow further. Thus, the fiber 120A helps to inhibit further crack growth. This behavior can occur not only with the fibers 120A, but also with all of the fibers 120 throughout the diamond structure 100. Furthermore, due to their strength and spreadability, the fibers can provide structural support for the cracked body by bridging between the cracked diamond matrix materials. As a result, the service life of the diamond structure can be increased.

  The fiber reinforced thermally stable diamond structure 100 shown in FIG. 3 includes fibers 120 that extend in one direction across the diamond matrix 110. This is shown as an example for clarity. In other embodiments, the fibers 120 extend across the diamond matrix in multiple directions, such as a lattice (with fibers oriented at 90 degrees to each) or more complex stitches (for each With fibers oriented at various angles. The fibers 120 may be spatially oriented in three dimensions. The orientation of the fibers can be predetermined or selected according to the desired application and the stresses expected for the material. In one embodiment, the fibers are randomly oriented.

  According to an embodiment, a method of forming a fiber reinforced thermally stable diamond structure is provided and illustrated in FIG. The method includes providing a fiber matrix (block 201), infiltrating graphite into the fiber matrix (block 202), and subsequently HPHT firing the graphite and fiber matrix at ultra high temperature and pressure without catalyst material. Tying (block 203). In one embodiment, the pressure is between about 100-160 kbar, for example about 150 kbar, and the temperature is about 1800-2500 ° C. HPHT sintering involves phase transformation of graphite to polycrystalline diamond (block 204). The result is a thermally stable polycrystalline diamond matrix with fibers spaced apart.

  The fiber matrix may be provided as a laminated or woven preform. The fibers are laid flat or woven in the desired orientation, for example by a weaving machine that passes the fibers through a sieve. The fiber may be fixed in situ with epoxy and heated or compressed into a single sheet or layer, referred to as a pre-preg (pre-impregnated with epoxy or resin), It can be pyrolyzed by heating to a substantially pure carbon material and subsequently converted to diamond. It is possible to use a plurality of fiber preform sheets having the desired fiber orientation. If the stress in the end use application is applied in one major direction, the fibers may be oriented parallel to one another in one major direction. If the stress is more unpredictable, the fibers may be woven in a number of different directions. Thus, the fibers may be oriented in a predetermined, desired direction prior to mixing with the carbide diamond material. Fiber preforms or prepregs may be purchased from commercial sources such as Fiber Materials, Inc. (Bidford, Maine). The fibers may be randomly oriented throughout the matrix, for example in the form of shorter fiber sections (commonly known as “whiskers”), for example 100-500 microns long. In this case, a composite material can be formed from graphite powder that is uniformly blended with fibrous whiskers, eliminating the need for fiber preforms or weaving.

  In one example embodiment, fiber preforms are laminated on top of each other in a desired configuration to form a fiber matrix for the diamond structure. Each fiber preform may be rotated relative to the underlying fiber preform to assemble a network of fibers extending in multiple directions. In one embodiment, the fiber preform is a sheet of woven fibers with pores or gaps extending between the fibers throughout the sheet. That is, the sheet is not solid. When the sheets are laminated together, they form a fiber skeleton that has passages that extend between the fibers throughout the laminated sheet.

  Next, the method includes infiltrating graphite into the fiber matrix, for example by chemical vapor deposition or chemical vapor infiltration. Chemical vapor deposition or infiltration can be performed by flowing a process gas, such as methane or hydrogen (or a mixture thereof), which acts as a chemical precursor, reacts, Graphite is deposited on the surface of the fiber matrix. Graphite is deposited layer by layer until the space between the stacked fibers fills the graphite. This step may be performed at a temperature of about 600 to 700 ° C. or higher.

  In some embodiments, various forms of pure carbon are mechanically blended together and then laminated with the fibers without chemical vapor deposition. The carbon may be graphite, diamond, and other forms of carbon, such as amorphous carbon, fullerene (Buckyball / C60, nanotube / nanofiber, etc.) or combinations thereof. The carbon may be mechanically blended using a variety of methods such as ball mill or attritor mill, ultrasonic mixing and the like. In certain embodiments, the mixture is further blended with a polymer, such as polyethylene carbonate or polypropylene carbonate, in preparation for forming a laminate. The carbon / polymer blend is then integrated with the fiber preform to form a laminate, as illustrated in FIGS. 7a and 7b. FIG. 7a shows a top view of the fiber preform 54 (as described above), and FIG. 7b shows a side view, displaying the process of integrating the fiber preform with the carbon / polymer blend. For clarity, the fiber preform 54 is shown as a row of fibers, but it should be understood that the fibers may be arranged in a fabric or layer so that the fibers extend in multiple directions. In FIG. 7 b, a mixture 50 of graphite powder and polymer binder is spread on a preform 54 and flattened by a blade 52. The carbon / polymer mixture 50 can be integrated with the fiber preform 54 to form a laminate by any suitable tape casting method, for example, by the doctor blade method illustrated in this figure. Also good. This lamination process may be repeated to form a fiber preform and carbon mixture that is laminated until an appropriate thickness is reached. After the polymer has been removed using conventional thermal degassing methods (exposed in vacuum or in an inert gas environment to a temperature of 300-1000 ° C.), the laminate is ready to be exposed to the HPHT treatment described below. Become.

  Thus, the desired form of carbon and fiber is brought together, for example, by chemical vapor deposition or lamination, as described above. The carbon and fiber matrix is subsequently cut into the desired shape so that it fits in the ultra high pressure press. Next, the method includes HPHT sintering the carbon and fiber matrix without a catalyst material. This involves HPHT sintering at ultra high temperature and pressure, which is higher than that applied during conventional HPHT sintering to form PCD. In one embodiment, the pressure is between about 100-160 kbar, for example about 150 kbar, and the temperature is about 1800-2500 ° C. For example, when sintering graphite, the pressure may be about 150 kbar, or about 150-160 kbar. When sintering other types of carbon, such as buckyballs or other composite carbon structures, the pressure may be about 110-120 kbar. For reference, conventional HPHT sintering to form PCD may be performed at about 50-60 kbar.

  The method transforms graphite into polycrystalline diamond. That is, during the HPHT sintering process, the graphite is converted to polycrystalline diamond without the aid of the catalyst material. Once HPHT sintering is complete, the result is a thermally stable polycrystalline diamond matrix with reinforcing fibers spaced apart. The fibers extend in the direction preselected by the placement of the fiber preform sheet throughout the diamond matrix.

  Optionally, a second HPHT sintering step at conventional temperature and pressure may be performed to incorporate the fiber reinforced thermally stable polycrystalline diamond structure into the PCD body with the substrate. . After a fiber-reinforced thermally stable polycrystalline diamond structure is cut into a desired shape by, for example, an electric discharge machine (EDM) or a laser cutting method, in a diamond powder mixture in contact with a substrate in a high-pressure press You may put it strategically. The fiber reinforced thermally stable polycrystalline diamond structure, diamond powder mixture, and substrate are then subjected to a conventional HPHT sintering process to convert the diamond powder to PCD and fiber reinforced thermal. A highly stable polycrystalline diamond structure is incorporated into the PCD body. In one embodiment, the fiber reinforced thermally stable polycrystalline diamond structure forms part of the cutting edge of the diamond body.

  An example of a cutting part 30 incorporating a fiber reinforced thermally stable polycrystalline diamond structure 100 is shown in FIG. The cutting component 30 includes a substrate 32 and a diamond body 34 bonded to the substrate. The diamond body 34 includes two regions: a first region 36 formed from PCD and a second region 38 formed from a fiber reinforced thermally stable polycrystalline diamond structure 100. Both regions 36 and 38 form part of the cutting edge 16 of the diamond body 34. The second region 38 forms about 25% of the cutting edge (on the periphery), or up to 50%, or up to 100% as shown in FIG. In other embodiments, the second region may form any portion of the cutting edge. In one embodiment, the second region 38a may be incorporated, for example as shown by the dashed line in FIG. Using this embodiment, the cutting component may be reused by rotating the cutting component so that the cutting edge in the region 38a comes to a position for cutting after the cutting edge region 38 is worn out. In another embodiment, the region 38b formed from the fiber reinforced thermally stable polycrystalline diamond structure 100 may form any upper portion of the diamond body. The upper portion may be limited only to the upper portion of the diamond body (eg, the upper portion occupying only the regions 38 and / or 38a) or may extend over the entire upper portion. In a further embodiment, the plurality of regions 38 formed from the fiber reinforced thermally stable polycrystalline diamond structure 100 may be located throughout the diamond body 34. In another embodiment, the entire diamond body may be formed from a fiber reinforced thermally stable polycrystalline diamond structure 100. In this latter embodiment, the diamond structure need not be placed in the diamond powder mixture. The size of the thermally stable polycrystalline diamond structure may be limited by the cell size of the press used to form the thermally stable polycrystalline diamond structure under high pressure. In one embodiment, the majority of the fibers in the fiber reinforced region 38 of the cutting part 30 are substantially intact after the ultra HPHT sintering process. FIG. 6 shows a drag bit 40 incorporating the cutting part of FIG. 5 according to an example embodiment. The drag bit 40 may include several cutting parts 30 and may be used for hot rock drilling operations. In other embodiments, other types of drilling or cutting tools may incorporate a cutting component in which a fiber reinforced thermally stable diamond matrix forms part of the cutting edge. For clarity, fiber reinforced regions 38 are shown for two of the cutting parts 30 of FIG. 6 and an example orientation of the fiber reinforced regions 38 on the blade 40 is displayed. It should be understood that other arrangements and orientations may be used.

  From both the diamond structure manufacturing process and the final working conditions, great demands have been made on the fibrous material itself. The fiber should be stronger and more malleable than the diamond matrix and must be able to withstand the extremely high pressures and temperatures of the ultra HPHT sintering process described above without degradation or reaction with diamond. . For example, carbon fibers are known as desirable reinforcing fibers in some applications, but carbon fibers may not withstand the ultra HPHT sintering process. On the contrary, the fiber structure can deteriorate by converting to diamond.

  The majority of fibers 120 remain substantially intact after the ultra HPHT sintering process. Fiber 120 may be formed from any material that has a greater critical stress than the polycrystalline diamond matrix material. In this context, critical stress means the fracture stress divided by the elastic modulus of the material. The fiber should also be formed from a material that is thermally stable at the ultra high temperature and pressure of the HPHT sintering process used to form the thermally stable polycrystalline diamond. For example, in various embodiments, the fibers 120 may be formed from silicon carbide, magnesium aluminosilicate, alumina, sapphire, or combinations thereof. In one embodiment, the fiber 120 is not formed from carbon. In one embodiment, the fiber 120 is non-metallic. In one embodiment, the fibers are cylindrical and have a diameter of about 10 microns. Since the fiber may extend across the length or diameter of the diamond structure, the length of the fiber depends on the particular diamond structure being formed. In one embodiment, the fibers comprise about 5-30% (by volume) of the diamond structure. In general, the lower the fiber percentage, the lower the toughness of the resulting diamond structure. However, if the fiber content is too low, for example below 5%, the beneficial properties contributed by the diamond matrix can be reduced.

  In one embodiment, the fiber reinforced thermally stable diamond structure is thermally stable above 700 ° C. and in another embodiment above 750 ° C. and has high strength at high temperatures (eg, (Strength of about 3.0 GPa over 1000 ° C.). In one embodiment, the polycrystalline diamond matrix has a hardness of about 4000 HV or greater.

In one embodiment, the fibers are coated prior to weaving or laying the fibers into the desired preform or prepreg. The coating is designed so that it can be peeled from the diamond matrix to absorb the stress applied to the material. This allows the diamond structure to absorb stress by peeling off this coating rather than cracking the diamond matrix. Thus, while the diamond matrix and fiber are both strong, the interface between the two is designed to be relatively weak. To achieve this, the fiber may be coated with a weak oxide material, such as magnesium oxide, cobalt oxide, or nickel oxide. The coating may be a few nanometers to 1-2 microns in thickness. The coating is applied prior to placing the fibers together in a desired or irregular orientation to form a fiber sheet or laminate. A fiber prepreg having coated fibers may be pre-manufactured or purchased. Other oxides that may be used alone or in combination with other coating materials are zirconium oxide, silicon dioxide, titanium dioxide, and aluminum oxide. Carbides of silicon, titanium, vanadium, chromium, zirconium, niobium, molybdenum, hafnium, tantalum, and tungsten may also be used alone or in combination with other coating materials. In addition, silicates such as Yb ₂ SiO ₅ , Yb ₂ SiO ₇ , Ho ₂ Si ₂ O ₇ , Re ₂ Si ₂ O ₇ , or LaMgAl ₁₁ O ₁₉ may also be used for fiber coating.

  In an alternative embodiment, the increased toughness is obtained by reinforcing the PCD carbonate, another type of thermally stable diamond, with fibers. PCD carbonate is a thermally stable form of PCD, in which case magnesium carbonate or calcium carbonate is used as the catalyst material rather than cobalt or another solvent metal. Magnesium carbonate, or calcium carbonate, is more thermally stable than other types of catalysts because the carbonic acid catalyst does not catalyze the conversion of carbon to graphite and catalyzes metal catalysts. Tend. In this case, the fiber base material is not filled with graphite using chemical vapor deposition or infiltration, but the fiber base material preform sheet and carbonated PCD powder are alternately replaced to assemble the fiber and diamond powder stack. This is, for example, as shown in FIG. A partial cross-sectional view of a pre-sintered mixture 300 of diamond carbonate powder 302 and laminated pre-formed fiber layer 304 according to an example embodiment is shown in FIG. Diamond powder may be mixed with a polymer to form the powder into a uniform layer 302 for lamination. The laminated structure 300 is then HPHT sintered at about 80 kbar and about 2000 ° C. to form a fiber reinforced thermally stable carbonated PCD structure.

  Although described in detail above for only a few embodiments, those skilled in the art will readily appreciate that many modifications can be made in the example embodiments without significantly departing from the invention. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. Except where the claims explicitly use the vocabulary “means for” together with the associated function, US Pat. It is the express intent of this application to not exercise.

Claims (21)

A polycrystalline diamond structure,
A diamond body having a thermally stable diamond matrix comprising diamond crystals bonded together;
A polycrystalline diamond structure comprising: a plurality of fibers extending between said thermally stable diamond matrix, wherein said diamond matrix comprises a diamond volume content of at least 99%.   The polycrystalline diamond structure of claim 1, wherein the fibers comprise a greater fracture strain than diamond crystals.   The polycrystalline diamond structure of claim 1, wherein the fibers comprise silicon carbide, alumina, sapphire, or magnesium aluminosilicate.   2. The polycrystalline diamond structure according to claim 1, wherein the fibers are oriented in a predetermined direction in the thermally stable diamond base material.   The polycrystalline diamond structure of claim 1, wherein the fibers are randomly oriented in the thermally stable diamond matrix.   The polycrystalline diamond structure of claim 1, wherein the diamond crystal is thermally stable above 700 ° C.   The polycrystalline diamond structure of claim 1, wherein the fiber comprises a coating that provides an interface between the fiber and the diamond crystal that is weaker than the diamond matrix.   The polycrystalline diamond structure of claim 7, wherein the coating comprises an oxide, carbide, or silicide material.   The polycrystalline diamond structure of claim 1, wherein the plurality of fibers occupy about 5-30% of the volume of the diamond body.   The polycrystalline diamond structure of claim 9, wherein the thermally stable diamond matrix accounts for the remaining 70-95% of the volume of the diamond body.   A shear cutter comprising the polycrystalline diamond structure of claim 1 directly or indirectly coupled to a substrate.   A drag bit comprising a body on which the shear cutter according to claim 9 is mounted. A method of forming a fiber reinforced thermally stable polycrystalline diamond structure comprising:
Providing a fiber matrix;
Infiltrating graphite into the fiber base material; and
A step of HPHT sintering the graphite and the fiber base material at an ultrahigh temperature and pressure without a catalyst material;
A method comprising the steps of:   The method of claim 13, wherein HPHT sintering includes the step of transforming the graphite into polycrystalline diamond.   14. The method of claim 13, wherein the ultra high temperature and pressure comprises a temperature of about 1800-2500C and a pressure of about 100-160 kbar.   The method of claim 13, further comprising orienting the fibers in a predetermined direction prior to infiltration.   14. The method of claim 13, further comprising orienting the fibers irregularly prior to infiltration. A polycrystalline diamond structure,
A diamond body comprising a diamond matrix comprising a single bonded diamond crystal and an interstitial space between the diamond crystals and comprising a carbonate catalyst disposed in the interstitial space; and
A plurality of fibers extending between the diamond matrix,
A polycrystalline diamond structure characterized by comprising:   The diamond structure of claim 18, wherein the fibers are oriented during lamination in the diamond body.   A shear cutter comprising the polycrystalline diamond structure of claim 18 directly or indirectly bonded to a substrate.   A drag bit comprising a body on which the shear cutter of claim 18 is mounted.

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