JP2013513031A - Polycrystalline diamond structure - Google Patents

Abstract

A PCD structure comprising a first region in a residual compressive stress state and a second region in a residual tensile stress state adjacent to the first region, wherein the first and second regions are each separate A PCD structure formed of a PCD grade and bonded directly to each other by intergrowth of diamond grains, wherein the PCD grade has a bending strength (TRS) of at least 1,200 MPa. The third region in the residual compressive stress state is also arranged so that the second region is disposed between the first and third regions and is bonded to the first and third regions by mutual growth of diamond grains. May be provided.

Description

  Aspects of the present invention include polycrystalline diamond (PCD) structures, elements comprising polycrystalline diamond structures, methods for making polycrystalline diamond structures, and particularly but not exclusively for use in rock decomposing or drilling, Or it relates to a tool comprising a polycrystalline diamond structure for drilling the ground.

  The PCD material comprises substantially intergrown diamond grain clusters and interstices between diamond grains. PCD may be produced by subjecting agglomerated masses of diamond grains to very high pressures and temperatures in the presence of a sintering aid, such as cobalt, that can promote intergrowth of diamond grains. . The sintering aid is sometimes referred to as a catalyst material for diamond. The gaps between the PCD materials may be wholly or partly filled with surplus catalyst material. The PCD may be integrally formed and bonded onto a cobalt sintered tungsten carbide substrate that may provide a source of cobalt catalyst material for sintering the PCD. As used herein, the term “integrally formed” region or portion means manufactured in close proximity to each other and not separated by other types of materials. Insertion tools that include PCD materials are widely used in drill bits used to drill ground in the oil and gas mining industry. While PCD materials are extremely wear resistant, PCD insertion tools need to have improved fracture resistance.

  PCT Patent Application Publication No. WO / 2004/111284 discloses a composite material comprising a plurality of PCD cores and a suitable binder dispersed in a matrix comprising a PCD material of a different grade than the core.

  Viewed from a first side, a PCD structure comprising a first region in a residual compressive stress state and a second region adjacent to the first region, wherein the second region is a residual tensile stress The first and second regions are each formed of a separate PCD grade and bonded directly to each other by intergrowth of diamond grains, and the PCD grade has a bending strength of at least 1,200 MPa ( A PCD structure having TRS) is provided.

  Viewed from the second side, each has at least two compression regions in a compressive residual stress state and at least one tensile region in a tensile residual stress state, the tensile region being disposed between the compression regions, PCD structures are provided that are integrally formed with each other. The compression region may include at least a first and third PCD grade, the tensile region may include a second PCD grade, and at least the second PCD grade has a resistance of at least about 1200 MPa. It may have a folding force (TRS). The second PCD grade may be selected to have a TRS of at least about 1,600 MPa or at least about 1,800 MPa.

  Viewed from a third aspect, a first plurality of agglomerates comprising diamond grains having a first average diameter and at least one second agglomerate comprising diamond grains having a second average diameter are provided. Arranging the first and second agglomerates in an alternating arrangement to form a pre-sintering assembly, and the pre-sintering assembly in the presence of a catalytic material for diamond, wherein diamond is more than graphite. A method of manufacturing a PCD structure is provided that includes processing at a thermodynamically stable ultra-high pressure and high temperature to sinter the diamond grains together to form an integral PCD structure.

  A PCD element comprising a PCD structure coupled to a cemented carbide support is provided. A tool comprising a PCD element is also provided. The tool may be a drill bit or drill bit component that pierces the ground, or a pick or anvil to break down or break hard materials such as asphalt or rock.

An example of the PCD structure will be described with reference to the accompanying drawings.
FIG. 3 shows a schematic perspective view of an example PCD cutter element for a drill bit used to drill the ground. The schematic cross section of the example of a part of PCD structure is shown. 1 shows a schematic cross-sectional view in the longitudinal direction of an example PCD element. 1 shows a schematic cross-sectional view in the longitudinal direction of an example PCD element. FIG. 2 shows a schematic perspective view of a portion of an example drill bit used to drill the ground. FIG. 2 shows a schematic longitudinal cross-sectional view of an example of an assembly before sintering for a PCD element. FIG. 3 shows a schematic longitudinal section of an example of a PCD element. A schematic cross section of a part of an example of a PCD structure is shown. A schematic cross section of a part of an example of a PCD structure is shown. A schematic cross section of a part of an example of a PCD structure is shown. A schematic cross section of a part of an example of a PCD structure is shown. FIG. 2 shows a schematic longitudinal partial cross-sectional view of an example of a PCD element. In all the drawings, the same reference numbers refer to the same general features.

  As used herein, polycrystalline diamond (PCD) is a mass of diamond grains wherein a substantial portion of the mass is directly interconnected with each other and the amount of diamond is at least about 80 volume percent of the material. It is a super hard material comprising a lump of diamond. In one embodiment of the PCD material, the gaps between the diamond grains may be at least partially filled with a binder material comprising a catalyst for diamond. As used herein, “gap” or “gap region” is a region between diamond grains of PCD material. In the example of the PCD material, the gap or gap area may be substantially or partially filled with a material other than diamond, or may be substantially empty. An example of a PCD material may include at least one region where the catalyst material has been removed from the gap, leaving a gap void between the diamond grains. As used herein, a catalytic material for diamond is a material that can promote direct mutual growth of diamond grains.

  As used herein, a PCD grade is a PCD material characterized by the volume content and diameter of diamond grains, the volume content of interstitial areas between diamond grains, and the composition of the material that may be present in the interstitial areas. The grade of the PCD material provides an agglomeration of diamond grains having a size distribution suitable for the grade, optionally introducing a catalytic material or additive material into the agglomerated mass, and a catalytic material for diamond Agglomerates may be produced in the presence of a source by a process comprising subjecting the pressure and temperature to which diamond is more thermodynamically stable than graphite and the catalyst material is melting. Under these conditions, the molten catalyst material may penetrate into the agglomerated mass from the source and promote direct intergrowth between the diamond grains during the sintering process to form a PCD structure. Let's go. The agglomerates may comprise loose diamond grains or diamond grains held together by a binder material.

Different PCD grades have different microstructures and different mechanical properties such as elastic (or Young) modulus E, elastic modulus, flexural strength (TRS), toughness (eg so-called K ₁ C toughness), hardness, density and heat. It may have an expansion coefficient (CTE). Different PCD grades may be used for different applications. For example, the wear rate and puncture resistance of different PCD grades may be different.

The table below shows the approximate compositional properties and properties of three examples of PCD grades, referred to as PCD grades I, II and III. All PCD grades include gap regions filled with a material comprising cobalt metal, which is an example of a catalyst material for diamond.

  Referring to FIG. 1, an example PCD element 10 comprises a PCD structure 20 that is bonded or otherwise bonded to a support 30 that may include sintered tungsten carbide. The PCD structure 20 includes a PCD grade.

  As used herein, “stress state” refers to a compression, no stress, or tensile stress state. Compressive and tensile stress states are understood to be opposite stress states. In a cylindrical geometric system, the stress state may be axial, radial or circumferential, or a net stress state.

  Referring to FIG. 2, an example PCD structure 20 includes at least two compression regions 21 that are in a compressive stress state through a gap and at least one tensile region 22 that is in a tensile residual stress state. The tension region 22 is located between the compression regions 21 and is joined to the compression region 21. Tensile region 22 includes PCD grade I and compressed region 22 includes PCD grade III. In other variations, the tensile region 22 includes PCD grade II and the compression region 22 includes PCD grade III.

  A PCD grade may be selected to achieve an arrangement in which the tensile region is between two compression regions. For example, changes in mechanical properties such as density, modulus of elasticity, hardness and coefficient of thermal expansion (CTE) may be selected for this purpose. Such changes may be realized by changes in diamond grain content, filler content and type, diameter distribution or average diameter of PCD grains.

  With reference to FIG. 3, an example PCD element 10 includes a PCD structure 20 integrally bonded to a cemented carbide support 30. The PCD structure 20 includes a plurality of compressed regions 21 and a plurality of tensile regions 22 in the form of alternating (or bound) layers or layers. The PCD element 10 comprises a PCD structure 20 located at the working end and defining a working surface 24 and may be substantially cylindrical in shape. The PCD structure 20 may be bonded to the support 30 at the non-planar interface 25. Tensile region 22 includes PCD grade II and compression region 22 includes PCD grade III. The compression region 21 and the tension region 22 may have a thickness of about 50 microns to about 200 microns and may be disposed substantially parallel to the working surface 24 of the PCD structure 20. A substantially annular region 26 may be placed around a non-planar feature 31 protruding from the support 30 and the annular region 26 comprises PCD grade II.

  With reference to FIG. 4, an example PCD element 10 includes a PCD structure 20 integrally bonded to a cemented carbide support 30 at a non-planar interface 25 opposite the working surface 24 of the PCD structure 20. Including. The PCD structure 20 may include about 10-20 alternating compression regions 21 and tension regions 22 in the form of an extended hierarchy. A region 26 that does not include a hierarchy may be disposed adjacent to the interface 25. The layers 21, 26 may be bent or bent, and may generally be aligned parallel to the interface 25, and may intersect the side surface 27 of the PCD structure. Some of the hierarchies may intersect the working surface 24.

  Referring to FIG. 5, an example drill bit 60 for rock (not shown) drilling includes an example PCD element 10 mounted on a bit body 62. The PCD elements 10 are arranged such that each PCD structure 20 protrudes from a bit body 62 for cutting rock.

  An example of a method for manufacturing a PCD element will now be described. Agglomerates in the form of sheets comprising diamond grains held together by a binder material may be provided. Sheets are used in the industry, such as extrusion or tape casting, where slurry and binder materials containing diamond grains having individual diameter distributions suitable to produce the desired individual PCD grade can be applied and dried on the surface. May be produced by a method known in the art. Other methods for producing diamond-containing sheets may also be used, such as those described in US Pat. Nos. 5,766,394 and 6,446,740. Alternative methods of depositing the layer with diamond include spray methods such as thermal spraying. The binder material may include an aqueous organic binder such as methylcellulose or polyethylene glycol (PEG), and various sheets may be provided that include diamond grains having different diameter distributions, diamond content or additives. . For example, at least two sheets comprising diamonds having different average diameters may be provided, and a first and second set of disks may be cut from each first and second sheet. The sheet may also contain a catalyst material for diamond, such as cobalt, and / or an additive to suppress abnormal growth of diamond grains or an additive to improve the properties of the PCD material. For example, the sheet may contain from about 0.5 weight percent to about 5 weight percent vanadium carbide, chromium carbide or tungsten carbide. In one example, each set may include about 10-20 disks.

  A support comprising a cemented carbide may be provided wherein the cement or binder material comprises a catalytic material for diamond such as cobalt. The support may have a non-planar end or a substantially planar adjacent end upon which the PCD structure will be formed. The non-planar shape of the edge may be configured to reduce undesirable residual stresses between the PCD structure and the support. A cup may be provided for use in assembling the diamond-containing sheet on the support. The first and second sets of disks may be stacked on the bottom of the cup in an alternating order. In one aspect of the method, a layer of substantially loose diamond grains may be compacted on top of the disk. The support may then be inserted into the cup with the adjacent edge first, pressing the substantially loose diamond grain and moving the diamond grain slightly to conform to the shape of the non-planar edge of the support. By arranging them, an assembly before sintering is formed.

  The pre-sintered assembly is placed in an ultra high pressure furnace capsule and subjected to an ultra high pressure of at least about 5.5 GPa and a high temperature of about 1,300 degrees Celsius to sinter the diamond grains and become integral with the support PCD elements can be formed that include PCD structures bonded to each other. In one embodiment of the method, when the pre-sintering assembly is being processed at ultra high pressures and temperatures, the binder material in the support melts and penetrates the diamond grain hierarchy. The presence of the molten catalyst material from the support will promote the sintering of the diamond grains by mutual growth and form an integral layered PCD structure.

  In some embodiments of the method, the agglomerates may comprise substantially loose diamond grains or diamond grains held together by a binder material. The agglomerated mass may be granular, disc-like, wafer-like, or sheet-like, and may contain catalyst material for diamond and / or additives to reduce abnormal diamond grain growth, and For example, the agglomerates may be substantially free of catalyst material or additives. In one aspect, the first average diameter may be in the range of about 0.1 microns to about 15 microns, and the second average diameter may be in the range of about 10 microns to about 40 microns. In one aspect, the agglomerates may be collected on a cemented carbide support.

  With reference to FIG. 6A, an example of a pre-sintering assembly 40 for manufacturing a PCD element includes a support 30, a region 46 containing diamond grains compacted against a non-planar end of the support 30, and It may include a plurality of alternating diamond-containing agglomerates 41, 42 in the general shape of a disk or wafer stacked on the region 46. In some embodiments, the agglomerates may be in the form of loose diamond grains or granules. The pre-sinter assembly may be heated to remove the binder material in the stacked disc.

  Referring to FIG. 6B, an example PCD element 10 includes a PCD structure 20 that includes a plurality of alternating hierarchies 21, 22 formed of different individual grades of PCD material, and portions 26 that do not include hierarchies. Portions 26 may be jointly formed depending on the shape of the non-planar end of support 30 that is integrally bonded during processing at ultra high pressure. The alternating layers 21, 22 of different grades of PCD are joined together by direct diamond-to-diamond intergrowth to form an integral, rugged, layered PCD structure 20. The shape of the PCD layers 21 and 22 may be bent, curved or distorted in a sense as a result of being subjected to ultra high pressure. In some embodiments of the method, the agglomerates are placed in a pre-sintering assembly to allow for various levels of hierarchy within the PCD structure, taking into account possible placement distortions during ultra high pressure and high temperature processing. Other structures may be realized.

  The tiers 21, 22 may include different individual PCD grades as a result of the various average diamond grains in the tier. Because different types of discs 41, 42 contain diamond grains having various average diameters, resulting in different sized spaces between the diamond grains, different amounts of catalyst material are included in the pre-sintering assembly. It may penetrate into the disks 41, 42. Accordingly, the corresponding alternating PCD layers 21, 22 may contain different alternating amounts of diamond catalyst material. The content of the filler material in the tension region may be greater than the content in the respective compression region in units of volume percent.

  In one example, the compression layer may include diamond grains having an average diameter that is greater than the average diameter of the diamond grains in the tension layer. For example, the average diameter of the tensile layer diamond grains may be at most about 10 microns, at most about 5 microns, or even at most about 2 microns, and may be at least about 0.1 microns or at least about 1 micron. . In some embodiments, the average diameter of the diamond grains of each compression layer is at least about 5 microns, at least about 10 microns, or even at least about 15 microns, and at most about 30 microns or at most about 50 microns. .

  While not wishing to be bound by any particular theory, if the layered PCD structure can be cooled from the high temperature at which the layered PCD structure was formed, alternating layers comprising different amounts of metal catalyst material will result. It may shrink at different rates. This may be because metals shrink much more than diamond when cooled from high temperatures. This different shrinkage rate will cause adjacent hierarchies to pull each other and will induce opposing stresses within them.

  The PCD structure 10 described with reference to FIG. 6B may be machined by cutting to modify the shape and form a PCD element substantially as described with reference to FIG. This may include removing some of the curved tiers to form a substantially planar working surface and a substantially cylindrical side. The catalyst material may be removed from the region of the PCD structure adjacent to the working surface or sides or both the working surface and sides. This may be done by treating the PCD structure with acid to leach the catalyst material from between the diamond grains, or by other methods such as electrochemical methods. A thermally stable region may be provided that extends from the surface of the PCD structure to a depth of at least about 50 microns or at least about 100 microns and may be substantially porous. In one example, the substantially porous region may contain up to 2 weight percent catalyst material.

  With reference to FIG. 7A, a variant of PCD structure 20 includes at least three substantially planar layers 21, 22, which alternate substantially parallel to working surface 24 of PCD structure 20. Arranged in the arrangement and intersects the side 27 of the PCD structure.

  Referring to FIG. 7B, a variant of the PCD structure 20 includes at least three layers 21 and 22 arranged in an alternating arrangement, the layers having a curved surface or a curved shape, and at least a part of the layers is a PCD structure. Are inclined away from the working surface 24 and the cutting edge 28.

  Referring to FIG. 7C, a variant of the PCD structure 20 includes at least three layers 21, 22 arranged in an alternating arrangement, at least a portion of the layers being inclined so as to be away from the working surface 24 of the PCD structure. , Generally extending toward the cutting edge 28 of the PCD structure.

  Referring to FIG. 7D, a variant of the PCD structure 20 includes at least three layers 21, 22 arranged in an alternating arrangement, with at least some of the layers being aligned with the working surface 24 of the PCD structure. , At least some of the hierarchies are generally aligned with the side surface 27 of the PCD structure. The hierarchy may be a general ring that is partially circular and may be substantially concentric with the substantially cylindrical side 27 of the PCD structure 20.

  Referring to FIG. 8, an example PCD structure comprises a tensile region 100 in a tensile residual stress state and a compression region 120 in a compressive residual stress state. The tension region 100 is located adjacent to the compression region 120 and is joined to the compression region 120. Tensile region 100 includes a first PCD grade, such as PCD Grade I as described above, and compression region 120 includes a different PCD grade, such as PCD Grade III as described above.

  The PCD structure may have a surface area proximate to the working surface, the area comprising a PCD material having a Young's modulus of at most about 1,050 MPa or at most about 1,000 MPa. The surface region may comprise a thermally stable PCD material.

  Some examples of PCD structures may have at least 3, at least 5, at least 7, at least 10, or even at least 15 compression regions between which the tensile regions are disposed.

  Each layer or layer may have a thickness of at least about 50 microns, at least about 100 microns, or at least about 200 microns. Each layer or layer may have a thickness of up to about 500 microns. In some embodiments, each level or layer is at least about 0.05 percent, at least about 0.5% of the thickness of the PCD structure measured from one point on the working surface to one point on the other end. It may have a thickness of at least about 1 percent or at least about 2 percent. In some embodiments, each hierarchy or layer may have a thickness of at most about 5 percent of the thickness of the PCD structure.

  As used herein, the term “residual stress state” refers to the stress state of the body or a portion of the body in the absence of an externally applied load. The residual stress state of the PCD structure, including the layer structure, may be measured by using strain gauges and progressively removing material. In some example PCD elements, at least one compression region may have a compressive residual stress of at least about 50 MPa, at least about 100 MPa, at least about 200 MPa, at least about 400 MPa, or even at least about 600 MPa. The difference in magnitude of residual stress between adjacent tiers may be at least about 50 MPa, at least about 100 MPa, at least about 200 MPa, at least about 400 MPa, at least about 600 MPa, at least about 800 MPa, or even at least about 1,000 MPa. In one example, at least two consecutive compression or tension regions may have different residual stresses. The PCD structure may include at least three compression regions or tensile regions, each having a different compressive stress, and these regions are arranged in order of increasing or decreasing compressive stress or tensile stress, respectively.

In one example, each region may have an average toughness of up to 16 MPa · m ^1/2 . In some embodiments, each region may have an average hardness of at least about 50 GPa or at least about 60 GPa. Each region may have an average Young's modulus of at least about 900 MPa, at least about 950 MPa, at least about 1,000, or even at least about 1,050 MPa.

  As used herein, “bending force” (TRS) refers to a rod-shaped sample having a width W and a thickness T at three points: two points on one side of the sample and one point on the opposite side of the sample. Over time, the weight P may be measured by increasing the weight at a certain weight rate until the sample is destroyed. TRS is calculated based on the weight P, the dimension of the sample, and the distance L that is the distance between two load positions on one side. Such a measurement may also be referred to as a three-point bend test. Munz and T.W. As described by Fett in "Ceramics, mechanical properties, failure behavior, materials selection" (1999, Springer, Berlin). The TRS corresponding to a particular grade of PCD material is measured by measuring the TRS of a PCD sample consisting of that grade.

  Providing a PCD structure with a PCD hierarchy with alternating compressive and tensile stress states tends to increase the overall effective toughness of the PCD structure, while the potential incidence of delamination that tends to fray the hierarchy Can have the effect of increasing. While not wishing to be bound by a particular theory, delamination may tend to occur if the PCD tier is not strong enough to withstand the residual stress between tiers. This effect will be improved by selecting a PCD grade and in particular a PCD grade that forms a tensile region and having a sufficiently high TRS. The PCD grade TRS that forms the PCD grade or tensile region should be greater than the residual tension that would be experienced. One way to influence the amount of stress that a region will experience is to select the relative thickness of adjacent regions. For example, by selecting that the thickness of the tensile region is greater than the thickness of the adjacent compression region, the magnitude of the tensile stress in the tensile region will be reduced.

  The residual stress state of the region may change with temperature. In use, the temperature of the PCD structure may differ substantially between points close to the blade edge and points away from the blade edge. For some uses, the temperature near the cutting edge can reach several hundred degrees Celsius. If the temperature exceeds about 750 degrees Celsius, the diamond material may be converted to a graphite material in the presence of a catalytic material such as cobalt, which is undesirable. Thus, for some uses, alternating stress states in adjacent regions described herein should be considered at temperatures below about 750 degrees Celsius.

The K ₁ C toughness of PCD discs was measured using a diametral compression test, which was determined by Lammer (“Mechanical properties of coated diamonds”, Materials Science and Technology, volume 4, 1988, p. 23.) and Miess (Miess , D. and Rai, G., "Fracture toughness and thermal resistances of composed diamond compacts", Materials Science and Engineering, 1996, volume A209, number 1 to 2, pp. 270-276).

（式中、

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および

であり、ここで種々の材料が、それぞれ体積分率ｆ_１およびｆ_２の２つの部分に分けられ、１つに合計される。 Young's modulus is a kind of elastic modulus and is the degree of uniaxial strain that responds to uniaxial stress within the range of stress in which the material behaves elastically. A preferred method for measuring the Young's modulus E is to express the horizontal and vertical components of the speed of sound passing through the material with the formula:

(Where

, C _L and C _T are the vertical and horizontal speeds of the sound passing through the measured material, respectively, and ρ is the density of the material. ) To measure. The vertical and horizontal speeds of sound may be measured using ultrasound, as is well known in the art. If the material is a composite of various materials, the average Young's modulus may be estimated using one of three equations: one of the following harmonics, geometry, and compound laws:

and

Where the various materials are divided into two parts, volume fractions f ₁ and f ₂ , respectively, and summed into one.

  As used herein, the expression “formed of” means “consisting of, apart from potential small or insubstantial deviations in the composition or microstructure”. To do.

  Some combinations predicted from this disclosure are presented in the following sections.

1. A PCD structure comprising a first region, a second region and a third region, wherein the second region is disposed between the first and third regions and bonded by intergrowth of diamond grains;
Each region is formed with a respective PCD grade having a TRS of at least 1,200 MPa or at least 1,600 MPa, and the second region has a higher PCD grade than the respective PCD grades of the first and third regions. A PCD structure having an expansion coefficient (CTE). The second region may comprise a PCD grade having a CTE of at least 4 × 10 ⁻⁶ mm / ° C.

  2. A PCD structure comprising a first and third region each in a separate residual compressive stress state and a second region in a residual tensile stress state and disposed between the first and third regions The first, second and third regions are each formed with a separate PCD grade and bonded directly to each other by intergrowth of diamond grains, the PCD grade having a bending strength (TRS) of at least 1,200 MPa, PCD structure.

3. A PCD structure comprising a first region, a second region and a third region, wherein the second region is disposed between the first and third regions and bonded by intergrowth of diamond grains;
Each region is formed with a respective PCD grade comprising at least 85 volume percent diamond grains having an average diameter of at least 0.1 microns and at most 30 microns, wherein the second region PCD grade is A PCD structure comprising a higher content of metal than the metal contained in the respective PCD grade contained in the third region. The PCD grade included in the second region may include at least 9 volume percent metal.

4). A PCD structure comprising a first region, a second region and a third region, wherein the second region is disposed between the first and third regions and bonded by intergrowth of diamond grains;
Each region is formed of a separate PCD grade having a TRS of at least 1,200 MPa, and a PCD grade included in the second region is included in each of the individual PCD grades included in the first and third regions. A PCD structure comprising more metal than metal. The PCD grade included in the second region may include at least 9 volume percent metal.

  5). In all combinations numbered 1-4 above, the PCD structure may include a thermally stable region extending from the surface of the PCD structure to a depth of at least 50 microns, where thermal The more stable region contains at most 2 weight percent diamond catalyst material.

  6). In all combinations numbered 1 to 5 above, the regions are in the form of layers arranged in an alternating arrangement, and may form an integral layered PCD structure. The hierarchy may have a thickness of at least about 10 microns and at most about 500 microns, and the hierarchy may be generally planar, curved, curved or hemispherical.

  7). In all combinations numbered 1-6 above, the region may intersect the working surface or side of the PCD structure. The PCD grades included in the first and third regions may include diamond grains having an average diameter different from that of the diamond grains contained in the second PCD grade.

  8). In all combinations numbered 1-7 above, the volume or thickness of the second region may be greater than the volume or thickness of the first region and the volume or thickness of the third region.

  A PCD element can be provided that includes a PCD structure coupled to a cemented carbide support. The PCD element may be substantially cylindrical and may have a substantially planar working surface or a generally hemispherical, pointed, circular cone or frustoconical working surface. Good. The PCD element may be for a rotary shear (or drag) bit for drilling the ground, for a hammer drill bit, or for a pick for crushed or asphalt cracking.

  The PCD elements described herein have aspects of improved resistance to failure.

  A non-limiting example of a PCD element that includes an alternating hierarchy of two different grades of PCD is provided below.

  First and second sheets having different average diameters and containing diamond grains held together with an organic binder were produced by a tape casting method. The method includes providing a respective slurry of diamond grains suspended in a liquid binder, forming the slurry into a sheet form, and drying them to form a self-supporting diamond-containing sheet. The average diameter of the diamond grains in the first sheet is in the range of about 5 microns to about 14 microns, and the average diameter of the diamond grains in the second sheet is in the range of about 18 microns to about 25 microns. there were. Both sheets contained about 3 weight percent vanadium carbide and about 1 weight percent cobalt. After drying, the sheet was about 0.12 mm thick. Fifteen circular disks having a diameter of about 13 mm were cut from each sheet to prepare first and second sets of disk-type wafers.

  A support made of cobalt sintered tungsten carbide was prepared. The support was generally in the form of a cylinder and included a non-planar end formed with a diameter of about 13 mm and a central protrusion. A metal cup having an inner diameter of about 13 mm was prepared for assembling the pre-sintering assembly. Diamond containing wafers were placed in cups and the stacked discs from the first and second sets were stacked alternately on top of each other. Place the layer of loose diamond grains having an average diameter in the range of about 18 microns to about 25 microns on the top layer of the wafer in a flipped cup and hold the support while pressing the non-planar edge against the layer. Inserted into the cup.

  The pre-sintered assembly thus formed is assembled into a capsule for an ultra-high pressure press and exposed to a pressure of about 6.8 GPa and a temperature of at least about 1,450 degrees Celsius for about 10 minutes to sinter and support the diamond grains. A PCD element was formed comprising a PCD structure bonded to the body.

  The PCD element was machined by cutting and lapping to form a cutter element having a substantially planar working surface and cylindrical sides, and a 45 degree chamfer between the working surface and sides. The cutter element was subjected to a test called a turret milling test to cut the granite mass until the PCD structure was broken or was worn so severely that no more effective cutting could be achieved. The test was stopped at various intervals, the cutter elements were observed, and the size of the wear scar formed in the PCD structure as a result of cutting was measured. The PCD cutter showed better wear and fracture resistance as would be expected from a PCD material with aggregate, non-hierarchical microstructure and constituent grade properties.

  The cross section passing through the PCD structure was also observed for a fine structure using a scanning electron microscope (SEM). The curved PCD layers were clearly seen, with each layer having a thickness in the range of about 50 microns to about 70 microns.

Claims (18)

  A PCD structure comprising a first region in a residual compressive stress state and a second region adjacent to the first region, wherein the second region is in a residual tensile stress state, A PCD structure in which the second regions are each formed of a separate PCD grade and are bonded directly to each other by mutual growth of diamond grains, said PCD grade having a bending strength (TRS) of at least 1,200 MPa .   The PCD structure of claim 1, wherein the PCD grade of the second region has a higher coefficient of thermal expansion (CTE) than the PCD grade of the first region.   The PCD structure according to claim 1 or 2, wherein the PCD grade of the second region has a lower elastic modulus than the PCD grade of the first region.   A PCD structure further comprising a third region in a separate residual compressive stress state, wherein the second region is disposed between the first and third regions, the first, second and second The three regions are each formed of a separate PCD grade and are directly bonded to each other by intergrowth of diamond grains, wherein the PCD grade has a bending strength (TRS) of at least 1,200 MPa. The PCD structure described. The PCD structure of claim 4, wherein the second region comprises a PCD grade having a CTE of at least 4 × 10 ⁻⁶ mm / ° C.   6. A PCD structure according to claim 4 or 5, wherein the region has a thickness of at least 10 microns and at most 500 microns.   The PCD structure according to any one of claims 4 to 6, wherein a volume of the second region is larger than a volume of the first region and a volume of the third region.   The PCD structure according to claim 1, wherein the region intersects a working surface or a side surface of the PDC structure.   The PCD grade contained in the first and third regions comprises diamond grains having an average diameter different from the PDC grade diamond grains contained in the second region. The PCD structure according to any one of the above.   10. The PCD grade included in the second region is included at a higher metal volume content than that included in the PCD grade of the third region. The PCD structure described.   2. A thermally stable region extending to a depth of at least 50 microns from a surface of the PCD structure, wherein the thermally stable region comprises at most 2 weight percent catalyst material for diamond. The PCD structure according to any one of 10.   The PCD structure according to claim 1, wherein the region is hierarchical.   A PCD structure comprising a first set of one or more hierarchies comprising a first grade of PCD material and a second set of hierarchies comprising a second grade of PCD material, the first set of said hierarchies 13. Interleaved with the second set of hierarchies, wherein the hierarchies are joined together by direct intergrowth of diamond grains to form an integral hierarchical PCD structure. PCD structure.   Providing a first plurality of agglomerates comprising diamond grains having a first average diameter and at least one second agglomerate comprising diamond grains having a second average diameter, said first and second Interstitial agglomerates of sinters to form a pre-sintering assembly, and the pre-sintering assembly is superheated in the presence of a catalyst material for diamond, wherein diamond is thermodynamically more stable than graphite. A method of manufacturing a PCD structure comprising: processing at high pressure and high temperature to sinter the diamond grains together to form an integral PCD structure.   The method of claim 14, wherein the agglomerate mass comprises diamond grains held together by a binder material.   16. The method of claim 14 or 15, wherein the first average diameter is from 0.1 microns to 15 microns and the second average diameter is from 10 microns to 40 microns.   A PCD element for a rotary shear bit for drilling the ground, a hammer drill bit, or a pick for picking for mining or asphalt disassembly, combined with a cemented carbide support that can be provided. A PCD element comprising the PCD structure according to any one of the preceding claims.   A drill bit or drill bit component for drilling ground, comprising the PCD element of claim 17.

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