Double Sintered Thermally Stable Polycrystalline Diamond Cutting Elements
Embodiments of the invention include a polycrystalline diamond compact comprising a plurality of double-sintered polycrystalline diamond segments. The polycrystalline diamond segments are configured to remain thermally stable at a first temperature. The polycrystalline diamond segments are positioned upon and bonded to a transition layer of single-sintered polycrystalline diamond that is configured to remain thermally stable at a second temperature lower than the first temperature. The transition layer is positioned upon and bonded to a substrate. Embodiments of the invention have improved thermally stability, resulting in fewer defects during manufacturing and improved longevity in use.
This application claims the benefit of and priority from U.S. Provisional Patent Application No. 61/164,770 filed on Mar. 30, 2009, which is incorporated herein in its entirety for all purposes by this reference.FIELD
Embodiments of the present invention relate generally to the field of earth boring tools and in particular relates to polycrystalline diamond cutting elements used on drill bits for earth boring.BACKGROUND
Specialized drill bits are used to drill well-bores, boreholes, or wells in the earth for a variety of purposes, including water wells; oil and gas wells; injection wells; geothermal wells; monitoring wells, mining; and, other similar operations. These drill bits come in two common types, roller cone drill bits and fixed cutter drill bits.
Wells and other holes in the earth are drilled by attaching or connecting a drill bit to some means of turning the drill bit. In some instances, such as in some mining applications, the drill bit is attached directly to a shaft that is turned by a motor, engine, drive, or other means of providing torque to rotate the drill bit.
In other applications, such as oil and gas drilling, the well may be several thousand feet or more in total depth. In these circumstances, the drill bit is connected to the surface of the earth by what is referred to as a drill string and a motor or drive that rotates the drill bit. The drill string typically comprises several elements that may include a special down-hole motor configured to provide additional or, if a surfaces motor or drive is not provided, the only means of turning the drill bit. Special logging and directional tools to measure various physical characteristics of the geological formation being drilled and to measure the location of the drill bit and drill string may be employed. Additional drill collars, heavy, thick-walled pipe, typically provide weight that is used to push the drill bit into the formation. Finally, drill pipe connects these elements, the drill bit, down-hole motor, logging tools, and drill collars, to the surface where a motor or drive mechanism turns the entire drill string and, consequently, the drill bit, to engage the drill bit with the geological formation to drill the well-bore deeper.
As a well is drilled, fluid, typically a water or oil based fluid referred to as drilling mud is pumped down the drill string through the drill pipe and any other elements present and through the drill bit. Other types of drilling fluids are sometimes used, including air, nitrogen, foams, mists, and other combinations of gases, but for purposes of this application drilling fluid and/or drilling mud refers to any type of drilling fluid, including gases. In other words, drill bits typically have a fluid channel within the drill bit to allow the drilling mud to pass through the bit and out one or more jets, ports, or nozzles. The purpose of the drilling fluid is to cool and lubricate the drill bit, stabilize the well-bore from collapsing or allowing fluids present in the geological formation from entering the well-bore, and to carry fragments or cuttings removed by the drill bit up the annulus and out of the well-bore. While the drilling fluid typically is pumped through the inner annulus of the drill string and out of the drill bit, drilling fluid can be reverse-circulated. That is, the drilling fluid can be pumped down the annulus (the space between the exterior of the drill pipe and the wall of the well-bore) of the well-bore, across the face of the drill bit, and into the inner fluid channels of the drill bit through the jets or nozzles and up into the drill string.
Roller cone drill bits were the most common type of bit used historically and featured two or more rotating cones with cutting elements, or teeth, on each cone. Roller cone drill bits typically have a relatively short period of use as the cutting elements and support bearings for the roller cones typically wear out and fail after only 50 hours of drilling use.
Because of the relatively short life of roller cone bits, fixed cutter drill bits that employ very durable polycrystalline diamond (PCD) compact cutters, tungsten carbide cutters, natural or synthetic diamond, other hard materials, or combinations thereof, have been developed. These bits are referred to as fixed cutter bits because they employ cutting elements positioned on one or more fixed blades in selected locations or randomly distributed. Unlike roller cone bits that have cutting elements on a cone that rotates, in addition to the rotation imparted by a motor or drive, fixed cutter bits do not rotate independently of the rotation imparted by the motor or drive mechanism. Through varying improvements, the durability of fixed cutter bits has improved sufficiently to make them cost effective in terms of time saved during the drilling process when compared to the higher, up-front cost to manufacture the fixed cutter bits.
Typically, a diamond cutter for use in a drill bit having a geometric size and shape normally characterized by unleached diamond cutting elements fabricated by assembling a plurality of polycrystalline diamond compact cutting elements in an array in a cutting slug that supports the cutting element. A challenge occurs, however, in bonding the PCD cutting elements to the cutting slug because the cutting slug—typically a cemented carbide substrate—has a different material than the PCD cutting elements and, therefore, has different material properties, such as a different rate of thermal expansion than the PCD cutting element. The differences in material properties can cause thermal stresses that lead the PCD cutting element to crack, delaminate, or otherwise become weakened and/or damaged at the interface between the cutting slug and the PCD cutting element.
Thus, there exists a need for a PCD cutting element that is, at least in part, has improved thermal compatibility with the underlying cutting slug.
Further, there is a need for a PCD cutting element that has improved bonding to a cutting slug as compared to the prior art.
In addition, there is a need for a PCD manufacturing process that improves the yield of usable PCD cutting elements coupled to cutting slugs that reduces the probability that the PCD cutting elements break and/or crack during a double sintering process.SUMMARY
Various features and embodiments of the invention disclosed herein provide robust and durable PCD cutting elements coupled to a cutting slug. In addition, methods of coupling a PCD cutting elements to a cutting slug are also disclosed.
Embodiments of the invention include a first layer comprising at least one polycrystalline diamond segment positioned upon a second layer or transition layer. In those embodiments that include a plurality of PCD segments, a first PCD segment is positioned proximate a second PCD segment and separated therefrom by an interfacial boundary. The interfacial boundary optionally is non-planar relative to the first and/or the second PCD segment. Optionally, the interfacial boundary includes an abrasive material. Optionally, the interfacial boundary is contiguous with and formed of the same material as the second layer. In some embodiments, the first layer remains thermally stable at a higher temperature than the temperature below which the second table remains thermally stable. In some embodiments, the second layer is coupled to a substrate or cutting slug.
Embodiments of the PCD segments include those that have been processed to provide a granular structure comprising interstices with a reduced number of metallic catalysts. Other embodiments of the PCD segments include those that have been processed to provide a granular structure that include interstices infiltrated with a material that remains thermally stable at a higher temperature than the temperature below which the metallic catalysts remain thermally stable. Other embodiments of the granular structure of the PCD segments comprise interstices that include one or more non-metallic catalysts. Yet other embodiments of the granular structure of the PCD segments comprise substantially fully dense diamond, i.e., a granular structure being substantially free of voids and/or interstices with or without other materials within any remaining interstices.
Other embodiments of the invention include a body of abrasive material coupled to a substrate. The body includes a substantially pointed or conical shaped cutting surface. The body optionally includes one or more PCD segments coupled to and exposed in the conical cutting surface.
A method of forming a PCD cutting elements coupled to a cutting slug includes providing a canister or other container configured to receive a plurality of thermally stable pre-sintered polycrystalline diamond segments. The canister is filled with grains of polycrystalline diamond and, optionally, a catalytic material. The polycrystalline diamond segments are positioned upon the grains of polycrystalline diamond such that an interfacial boundary is formed from the grains of polycrystalline diamond to separate each of the plurality of polycrystalline diamond segments. A press than applies a temperature and a pressure to the container to sinter the grains of polycrystalline diamond and bond the polycrystalline diamond segments to the sintered grains of polycrystalline diamond.
As used herein, “at least one,” “one or more,” and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C,” “at least one of A, B, or C,” “one or more of A, B, and C,” “one or more of A, B, or C” and “A, B, and/or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together.
Various embodiments of the present inventions are set forth in the attached figures and in the Detailed Description as provided herein and as embodied by the claims. It should be understood, however, that this Summary does not contain all of the aspects and embodiments of the one or more present inventions, is not meant to be limiting or restrictive in any manner, and that the invention(s) as disclosed herein is/are and will be understood by those of ordinary skill in the art to encompass obvious improvements and modifications thereto.
Additional advantages of the present invention will become readily apparent from the following discussion, particularly when taken together with the accompanying drawings.
To further clarify the above and other advantages and features of the one or more present inventions, reference to specific embodiments thereof are illustrated in the appended drawings. The drawings depict only exemplary embodiments and are therefore not to be considered limiting. One or more embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
The drawings are not necessarily to scale.DETAILED DESCRIPTION
The plurality of PCD segments 110 are separated by an interfacial boundary 150 between each of the plurality of PCD segments 110. Optionally, the interfacial boundaries 150 comprises an abrasive material selected from a group that includes, but is not limited to, tungsten carbide, cubic boron nitride, thermally stable polycrystalline diamond, polycrystalline diamond, and the like. The interfacial boundaries 150 optionally are non-linear and/or non-planar relative to adjacent PCD segments 110. Optionally, the non-linear and/or non-planar quality of the interfacial boundary 150 creates an interlocking feature—best seen as interlocking feature 760 in
The PCD compact 101 also includes a second table or layer 115, also referred to as a transition layer 115. The PCD segments 110 are positioned upon and bonded to the second layer 115. The second layer 115 optionally comprises an abrasive material selected from a group that includes, but is not limited to, tungsten carbide, cubic boron nitride, thermally stable polycrystalline diamond, polycrystalline diamond, and the like. The embodiment of the PCD compact 101 illustrates a second layer 115 that includes sintered PCD grains 120 that is optionally interspersed with a metallic catalyst. Optionally, the second layer 115 is contiguous with and comprises the same material as the interfacial boundary 150. In the embodiment of the PCD compact 101 illustrated in
The second table 115 is bonded to a substrate 125 made from, for example, a metallic material. For example, the substrate 125 can be made from a metallic material selected from the group that includes, but is not limited to, tungsten carbide, titanium carbide, tungsten molybdenum carbide, tantalum carbide, combinations thereof, and other similar materials. In the embodiment of the PCD compact 101 illustrated in
As noted, the PCD segments 110 typically are formed by sintering powdered diamond, and, optionally, various catalysts, typically metallic powders mixed with the diamond powder. The catalysts, typically metallic materials, such as cobalt and other similar metallic materials, act as a catalyst to reduce the temperature and/or the pressure at which the sintering process occurs and/or speeds the reaction by which the diamond grains and any other materials crystallize and form a granular structure. The diamond powder and any catalysts and/or other materials are placed in a canister or form that is compressed under a pressure and a temperature sufficient to sinter and crystallize the diamond powder and any other materials into a solid PCD segment.
Cobalt and other catalysts, however, typically result in a PCD granular structure that typically suffers from thermal degradation at temperatures (typically around from about 650 degrees Celsius to about 700 degrees Celsius) that the PCD granular structure can be exposed to during normal use. That is, the PCD granular structure exhibits increased tendencies to fail, crack, chip, delaminate, or otherwise wear more quickly during use at normal operating temperatures, leading to premature wear and reduced life.
To address the side-effect the catalysts 310 have on the thermal stability of the PCD granular structure 300, the PCD segments (such as segments 110 in
The PCD grains 201 typically are submicron in size, providing dimensional context for the
Optionally, the PCD granular structure 200 is then subjected to additional processing, such as another sintering process (i.e., double sintering) to cause the PCD grains 201 to grow and expand into the interstices or voids 220, leaving PCD granular structure that is substantially diamond dense. That is, the PCD granular structure 200 comprises at least 90% PCD grains 201.
In other embodiments, the PCD granular structure 200 is sintered while in contact with non-catalytic materials, i.e., those materials that typically do not catalyze or cause the PCD granular structure to change crystal structure (e.g., from diamond to graphite) and/or lower the temperature at which the PCD granular structure 200 and PCD grains 201 begin to become thermally unstable. For example, a non-metallic catalyst 210 that is thermally stable, e.g., one having a coefficient of thermal expansion similar to that of the PCD grains 201 can be placed in contact with the PCD granular structure 201 during the sintering process, thereby causing the non-metallic catalyst 210 to infiltrate and/or grow within one or more of the interstices or voids 220. The non-metallic catalyst 210 can be selected from a group that includes, but is not limited to, silicon, silicon carbide, boron, carbonates, hydroxide, hydride, hydrate, phosphorus-oxide, phosphoric acid, carbonate, lanthanide, actinide, phosphate hydrate, hydrogen phosphate, phosphorus carbonate, combinations thereof, and other similar materials.
In yet other embodiments, the PCD granular structure 200 is sintered with one or more thermally stable materials 215, including, but not limited to, cobalt silicide, titanium, niobium, molybdenum, tungsten, tantalum, combinations thereof, and other similar materials. A benefit of these thermally stable materials 215 is that they tend to act to make the PCD granular structure 200 less brittle under impact loads.
Prior art PCD compacts typically had a PCD segment bonded directly to a substrate. This arrangement caused difficulties during manufacturing and use because, among other problems, the coefficient of thermal expansion differed, sometimes greatly, between the substrate and the PCD segment. During manufacturing, in which the PCD segment was to be bonded to the substrate, the different rates of thermal expansion often resulted in PCD segments that cracked due to the thermal stresses created at the interface of the substrate and the PCD segment as the substrate and PCD segment expanded and contracted at different rates while heating and cooling. Similar results occurred during use in which the PCD segment would be subjected to direct heating caused by friction, whereas the substrate is heated primarily through heat transferred by conduction through the PCD segment and to the substrate.
A benefit of the second layer or transition layer 115 is that it solves the previously unresolved problem of bonding a PCD segment to a substrate that has a different coefficient of thermal expansion. That is, embodiments of PCD compacts of the invention have improved thermal stability, improved bonding of the PCD segments to a substrate, improved reliability, and other benefits as described herein and one having skill in the art will understand by reading the disclosure.
Embodiments of methods of making first the PCD segments 110 are first discussed. As noted above, PCD segments 110 are formed by sintering diamond powder or other similar material and, optionally, a catalyst. Illustrated in
Embodiments of the method making PCD include providing a canister or can 601 as seen in
Prior to placing the lid 660 on the canister 601 and sealing the canister 601, the diamond powder 650 may be tamped down or compacted with an applied pressure low enough to avoid breakage of any of the discs 405 and 630. Optionally, the canister 650 is heated to reduce or eliminate some or all of any impurities present in the diamond powder 650 and elsewhere in the canister 601 before sealing the canister 601. Typically, the lid 660 is sealed to the canister 601 through welding, such as laser welding and other known methods. In some embodiments of the present invention, the canister is sealed using a process described in U.S. Pat. No. 7,575,425 to Hall et al., which is herein incorporated by reference for all that it contains.
After the canister 601 is sealed, it is placed within a salt form (not shown). One or more salt forms are then stacked and placed on an anvil of a high-temperature, high-pressure press (not shown). The press applies a pressure and a temperature sufficiently high to cause the diamond powder 650 (and any catalysts and other materials) to sinter. During the sintering process, the diamond powder 650 typically reduces in volume as it becomes solid.
Once the sintering process is complete and the canister 601 is removed from both the press and the salt form, the diamond powder 650 will have become the sintered PCD segments 110. An advantage of the ribs 420 of the discs 405 is that the separate PCD segments 110 are easily separable from the discs 420, thus eliminating a step of cutting the PCD segments 110 out a solid cylinder of polycrystalline diamond with an electron discharge machining (EDM), a process that typically is time consuming and expensive. The separated PCD segments 110 are now ready for any post-sintering treatment such as leaching and/or acid baths, and other such treatments to improve the thermal stability of the PCD segments 110 as discussed above.
Embodiments of the method further include forming PCD compacts, such as those illustrated in
The substrate 2625 is placed on top of the unsintered abrasive material 2620. Prior to placing the lid 2660 on the canister 2601 and sealing the canister 2601, the unsintered abrasive material 2620 may be tamped down or compacted with an applied pressure low enough to avoid breakage of any of the PCD segments 2610. Optionally, the canister 2601 is heated to reduce or eliminate some or all of any impurities present in the unsintered abrasive material 2620 and elsewhere in the canister 2601 before sealing the canister 2601. Typically, the lid 2660 is sealed to the canister 2601 through welding, such as laser welding and other known methods. In some embodiments of the present invention, the canister is sealed using a process described in U.S. Pat. No. 7,575,425 to Hall et al. After the canister 2601 is sealed, it is placed within a salt form (not shown). One or more salt forms are then stacked and placed on an anvil of a high-temperature, high-pressure press (not shown). The press applies a pressure and a temperature sufficiently high to cause the unsintered abrasive material 2620 (and any catalysts and other materials) to sinter. During the sintering process, the abrasive material 2620 typically reduces in volume as it becomes solid. In addition, the PCD segments 2610 undergo a second, or double, sintering process, by which the PCD grains grow and/or other non-metallic catalysts and/or other thermally stable materials are incorporated and sintered into the PCD segments as discussed above.
During the sintering process, the abrasive material 2620 forms both a mechanical and a chemical bond or attachment with the PCD segments 2610 at the interfacial boundary 2650 and at a lower surface 2611. For example, the PCD segments 2610 would exhibit, in part, growth of PCD grains 201 (
Another benefit is that whereas the PCD segments 2610—typically processed to be thermally stable—and the substrate 2625 typically have coefficients of thermal expansion that are quite different, as discussed above, the layer of sintered abrasive material 2620 acts as a transition layer, and is typically selected and prepared to have a coefficient of thermal expansion somewhere between that of the PCD segments 2610 and the substrate 2625. In so doing, the gradient of thermal stresses is changed gradually throughout the PCD compact rather than having a sharp transition at each interface. That is, a first layer of PCD segments 2610 is configured to remain thermally stable at a first temperature and a second layer or transition layer 2620 is configured to remain thermally stable at a second temperature lower than the first temperature.
For example, the PCD compact 710 includes two PCD segments 710 and a single interfacial boundary 750 that is non-linear and non-planar and includes interlocking features 760, such as the illustrated dimples.
As illustrated in
As noted, the interfacial boundaries 750, 950, and others can include comprise interlocking features. The interfacial boundaries 950 includes a series of steps 960. The interlocking features 750, 850, 950, 1050, 1150, 1250, 1350, and 1450 optionally include also comprise complementary projections and recesses. For example, PCD compact 1201 in
Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.
The present invention, in various embodiments, includes providing devices and processes in the absence of items not depicted and/or described herein or in various embodiments hereof, including in the absence of such items as may have been used in previous devices or processes, e.g., for improving performance, achieving ease and/or reducing cost of implementation.
The foregoing discussion of the invention has been presented for purposes of illustration and description. The foregoing is not intended to limit the invention to the form or forms disclosed herein. In the foregoing Detailed Description for example, various features of the invention are grouped together in one or more embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the following claims are hereby incorporated into this Detailed Description, with each claim standing on its own as a separate preferred embodiment of the invention.
Moreover, though the description of the invention has included description of one or more embodiments and certain variations and modifications, other variations and modifications are within the scope of the invention, e.g., as may be within the skill and knowledge of those in the art, after understanding the present disclosure. It is intended to obtain rights which include alternative embodiments to the extent permitted, including alternate, interchangeable and/or equivalent structures, functions, ranges or steps to those claimed, whether or not such alternate, interchangeable and/or equivalent structures, functions, ranges or steps are disclosed herein, and without intending to publicly dedicate any patentable subject matter.
1. A polycrystalline diamond compact comprising:
- a first layer, said first layer including a plurality of polycrystalline diamond segments positioned thereupon; said plurality of polycrystalline diamond segments being separated by an interfacial boundary formed of an abrasive material;
- a second layer, said first layer being bonded to a second layer, said second layer being formed in part from said abrasive material; and,
- a substrate, said second layer being positioned upon and bonded to said substrate.
2. The compact of claim 1, wherein said polycrystalline diamond segments have a granular structure comprised of polycrystalline diamond grains and interstices, said interstices being substantially free of a catalytic material.
3. The compact of claim 2, wherein said interstices include a non-catalytic material.
4. The compact of claim 3, wherein said non-catalytic material is a non-metallic material.
5. The compact of claim 1, wherein said polycrystalline diamond segments have a granular structure comprised substantially of polycrystalline diamond grains and substantially free of interstices.
6. The compact of claim 1, wherein said abrasive material comprises a granular structure comprised of polycrystalline diamond grains and a catalyst.
7. The compact of claim 1, wherein the second layer further comprises a substantially conical surface.
8. The compact of claim 1, wherein said first layer is configured to remain thermally stable at a first temperature and said second layer is configured to remain thermally stable at a second temperature lower than said first temperature.
9. A polycrystalline diamond compact comprising:
- a plurality of double-sintered polycrystalline diamond segments, said diamond segments configured to remain thermally stable at a first temperature;
- a transition layer of single-sintered polycrystalline diamond configured to remain thermally stable at a second temperature lower than said first temperature, said polycrystalline diamond segments positioned upon and bonded to said transition layer; and,
- a substrate, said transition layer positioned upon and bonded to said substrate.
10. The compact of claim 9, wherein said polycrystalline diamond segments have a granular structure comprised of polycrystalline diamond grains and interstices, said interstices being substantially free of a catalytic material.
11. The compact of claim 10, wherein said interstices include a non-catalytic material.
12. The compact of claim 11, wherein said non-catalytic material is a non-metallic material.
13. The compact of claim 9, wherein said polycrystalline diamond segments have a granular structure comprised substantially of polycrystalline diamond grains and substantially free of interstices.
14. The compact of claim 9, wherein said transition layer comprises a granular structure comprised of polycrystalline diamond grains and a catalyst.
15. The compact of claim 9, wherein the transition layer further comprises a substantially conical surface.
16. A method of forming a polycrystalline diamond compact comprising:
- providing a canister configured to receive a plurality of sintered polycrystalline diamond segments and an unsintered abrasive powder;
- filling said canister with said unsintered abrasive powder;
- positioning said plurality of polycrystalline diamond segments upon said unsintered abrasive powder, an interfacial boundary formed of said unsintered abrasive powder separating each of said plurality of polycrystalline diamond segments; and
- applying a temperature and a pressure to said canister to sinter said unsintered abrasive powder and bond said polycrystalline diamond segments to said sintered abrasive powder.
17. The method of claim 16, further comprising positioning a substrate in said canister, said unsintered abrasive powder being positioned between said substrate and said sintered polycrystalline diamond segments.
18. The method of claim 16, further comprising:
- providing another canister configured to receive at least a first disc, said first disc including at least one rib on a front surface of said first disc;
- filling said canister with at least diamond powder;
- placing said first disc in said canister such that said front surface of said first disc is in contact with said diamond powder; and,
- applying a temperature and a pressure to said canister to sinter said diamond powder to form said sintered polycrystalline diamond segments.
19. The method of claim 18, further comprising:
- removing said sintered polycrystalline diamond segments from said another canister;
- processing said polycrystalline diamond segments to make said polycrystalline diamond segments more thermally stable than unprocessed polycrystalline diamond segments.
International Classification: E21B 10/46 (20060101); B24D 3/00 (20060101); E21B 10/567 (20060101);