High-impact-resistance polycrystalline diamond compact for oil and gas drilling and preparation method thereof

Abstract

This invention discloses a high-impact polycrystalline diamond composite sheet for oil and gas drilling and its preparation method. The polycrystalline diamond composite sheet consists of a cemented carbide matrix and a polycrystalline diamond layer disposed on the cemented carbide matrix. The polycrystalline diamond layer includes a surface layer and at least one transition layer. Each transition layer contains diamond particles with two principal particle sizes, wherein the finer principal particle size distribution at least partially overlaps with the principal particle size distribution of the surface layer or the coarser principal particle size distribution of the previous transition layer. A cobalt gradient layer is provided at one end of the cemented carbide matrix near the polycrystalline diamond layer, and the cobalt content of the cobalt gradient layer decreases gradually towards the polycrystalline diamond layer. This invention employs a dual principal particle size design in the transition layer, and designs that the principal particle size distributions of the surface layer and the transition layer, as well as between the transition layers, at least partially overlap, and reduces the cobalt content near the interface of the cemented carbide matrix, thereby improving the impact resistance of the polycrystalline diamond composite sheet.

Description

Technical Field

[0001] This invention relates to the field of superhard materials technology, and in particular to a high-impact polycrystalline diamond composite sheet for oil and gas drilling and its preparation method. Background Technology

[0002] Polycrystalline diamond composite sheets are made by assembling diamond powder and a cemented carbide matrix together through various parts and sintering under high temperature and ultra-high pressure. They combine the high hardness and wear resistance of diamond with the impact resistance and weldability of cemented carbide, making them the most important cutting element in diamond drill bits for oil and gas drilling. Their performance directly affects the drilling efficiency and service life of the drill bit. When drilling into complex and difficult-to-drill formations such as gravel-bearing or mixed hard and soft formations, the polycrystalline diamond composite sheet, as the cutting element, often fails to adapt to the changes in heterogeneous formations, resulting in premature impact damage and affecting its performance. In gravel-bearing formations, polycrystalline diamond composite wafers are prone to chipping and breakage when cutting gravel, which is a major cause of premature damage to the cutting elements of diamond drill bits. In mixed soft and hard formations, when drilling from soft formations to hard interlayers, the profile of the drill bit crown causes uneven stress on the composite wafers at different parts of the drill bit, resulting in drill bit jamming and skipping, which in turn leads to increased stress on the composite wafers, causing them to chip or break. Therefore, these types of formations place higher demands on the impact resistance of polycrystalline diamond composite wafers.

[0003] For polycrystalline diamond composite sheets used in oil and gas drilling, finer diamond particles in the polycrystalline diamond layer offer better wear resistance but poorer impact resistance, while coarser particles offer better impact resistance but poorer wear resistance—a contradiction. Current technologies primarily improve the overall impact resistance of the composite sheet by designing a surface layer of fine-grained diamond and a transition layer of coarse-grained diamond. However, under high pressure, coarse-grained diamond is more prone to extrusion defects or breakage, thus reducing the improvement in impact resistance. Furthermore, the significant differences in thermal expansion coefficients and elastic moduli between diamond and the cemented carbide matrix lead to substantial residual stress after sintering, negatively impacting the impact resistance of the polycrystalline diamond composite sheet. During the preparation of the diamond composite sheet, the fine particle size of the diamond powder inevitably leads to the adsorption of various gases and impurities during mixing and assembly, reducing surface cleanliness and activity, ultimately affecting sintering quality, D-D bonding, and overall product performance. Summary of the Invention

[0004] To improve the impact resistance of polycrystalline diamond composite sheets, this invention improves the impact resistance of polycrystalline diamond composite sheets by designing the particle size distribution of the polycrystalline diamond layer while ensuring a certain level of wear resistance. Furthermore, this invention reduces the cobalt content at the interface of the cemented carbide matrix to decrease the difference in thermal expansion coefficient and elastic modulus between the cemented carbide matrix and the polycrystalline diamond layer, thereby reducing the adverse effects of residual stress on the impact resistance of the polycrystalline diamond composite sheets.

[0005] The technical solution provided by this invention is as follows:

[0006] In a first aspect, the present invention provides a high-impact polycrystalline diamond composite sheet for oil and gas drilling, comprising a cemented carbide matrix and a polycrystalline diamond layer disposed on the cemented carbide matrix; wherein:

[0007] The polycrystalline diamond layer includes a surface layer and at least one transition layer; the diamond particles in each transition layer include two principal sizes, wherein the fine principal size distribution at least partially overlaps with the principal size distribution of the surface layer or the coarse principal size distribution of the previous transition layer.

[0008] The cemented carbide substrate has a cobalt gradient layer at one end near the polycrystalline diamond layer. The cobalt content of the cobalt gradient layer decreases in a gradient direction near the polycrystalline diamond layer. The cobalt content of the cobalt gradient layer at the interface adjacent to the polycrystalline diamond layer is 60wt% to 90wt% of the cemented carbide substrate outside the cobalt gradient layer.

[0009] The diamond particles in each transition layer of this invention include two principal particle sizes, wherein the finer principal particle size at least partially overlaps with one principal particle size of the surface layer or the previous transition layer. Since the principal particle size distributions of adjacent layers overlap or are similar, the bonding strength increases, and the overall impact resistance of the polycrystalline diamond composite sheet is improved.

[0010] This invention incorporates a cobalt gradient layer at one end of the cemented carbide substrate near the polycrystalline diamond layer. The cobalt content of the cobalt gradient layer at the interface adjacent to the polycrystalline diamond layer is 60wt%–90wt% of the cobalt in the cemented carbide substrate outside the cobalt gradient layer. The closer the cobalt gradient layer is to the interface, the lower its concentration, resulting in a lower coefficient of thermal expansion, a higher elastic modulus, and a smaller difference in thermal expansion coefficient and elastic modulus between the cobalt gradient layer and the polycrystalline diamond layer. This leads to less residual stress generated during vacuum high-temperature and high-pressure sintering, and thus less adverse impact of residual stress on the impact resistance of the polycrystalline diamond composite sheet. This invention maintains a normal cobalt content in the substrate outside the cobalt gradient layer, ensuring the overall fracture toughness and brazability of the substrate.

[0011] In some embodiments provided by the present invention, each transition layer includes two principal grain sizes, and the D50 difference between the two principal grain sizes is 15 to 35 micrometers.

[0012] In some embodiments provided by the present invention, the fine main particle size accounts for 30wt% to 60wt% of the transition layer.

[0013] In some embodiments provided by this invention, the particle size distribution curve of the surface principal particle size exhibits a single-peak shape, and the particle size distribution satisfies...

[0014] In some embodiments provided by the present invention, the main particle size of the transition layer is formed by mixing two particle sizes, coarse and fine, in a mass ratio of 3:1 to 0.5:1. The fine particle size is 10 to 60 micrometers, and the coarse particle size is 30 to 80 micrometers. Before mixing, the particle size distribution characteristics of each particle size are the same as those of the main particle size of the surface layer. After mixing, the particle size distribution curve is bimodal.

[0015] In some embodiments provided by the present invention, the polycrystalline diamond layer is composed of a surface layer and a first transition layer; the principal particle size of the surface layer is A1, and the principal particle sizes of the first transition layer are B1 and C1, where A1 and B1 are both smaller than C1, and A1 and B1 at least partially overlap.

[0016] In some embodiments provided by the present invention, A1 is 10-40 micrometers, B1 is 10-40 micrometers, and C1 is 30-60 micrometers. Preferably, A1 is 20-30 micrometers, B1 is 20-30 micrometers, and C1 is 50-60 micrometers.

[0017] In some embodiments provided by the present invention, the polycrystalline diamond layer is composed of a surface layer, a first transition layer, and a second transition layer; the principal particle size of the surface layer is A2, the principal particle sizes of the first transition layer are B2 and C2, and the diamond particles of the second transition layer include principal particle sizes D and E, A2 and B2 are both smaller than C2, C2 and D are both smaller than E, and A2 and B2 at least partially overlap, and C2 and D at least partially overlap.

[0018] In some embodiments provided by the present invention, A2 is 10-40 micrometers, B2 is 10-60 micrometers, D is 10-60 micrometers, C2 is 30-80 micrometers, and E is 30-80 micrometers. Preferably, A2 is 15-25 micrometers, B2 is 10-20 micrometers, C2 is 30-40 micrometers, D is 30-40 micrometers, and E is 60-80 micrometers.

[0019] In some embodiments provided by the present invention, the cobalt content of the cobalt gradient layer outer cemented carbide substrate is 10wt% to 16wt%.

[0020] In some embodiments provided by the present invention, the thickness of the cobalt gradient layer is 0.5 to 5.0 mm.

[0021] In a second aspect, the present invention provides a method for preparing the above-mentioned high-impact polycrystalline diamond composite sheet for oil and gas drilling, comprising:

[0022] A cemented carbide substrate with a cobalt content of 10wt% to 16wt% is placed in a carburizing atmosphere and treated at 1000 to 1400°C for 60 to 240 minutes to form a cobalt gradient layer.

[0023] The polycrystalline diamond layer powder is subjected to high-temperature reduction to obtain purified polycrystalline diamond layer powder.

[0024] The purified polycrystalline diamond powder, cemented carbide matrix, and various assembly components are assembled internally and externally to form an external composite mold.

[0025] The outer molding die is placed into a six-sided press and sintered under vacuum, high temperature and high pressure to obtain a polycrystalline diamond composite sheet.

[0026] The present invention employs high-temperature reduction purification treatment of powder and vacuum high-temperature activation treatment of internal synthesis mold during the preparation process, which can effectively improve the cleanliness and sintering activity of powder, thereby improving the sintering quality of polycrystalline diamond layer and the density of D-D bonding.

[0027] The polycrystalline diamond composite sheet for oil and gas drilling provided by this invention has the following beneficial effects:

[0028] 1. The surface layer of the polycrystalline diamond layer uses fine-grained diamond particles as the wear-resistant layer, while the transition layer uses a mixture of coarse and fine diamond particles with a bimodal distribution as the impact-resistant layer. The fine particles in the transition layer are evenly distributed around the coarse particles, reducing direct contact between the coarse particles and thus reducing the probability of defects caused by mutual compression of the coarse particles, ensuring the overall impact toughness of the transition layer. In addition, the main particle size distribution of the wear-resistant surface layer and the impact-resistant transition layer overlaps or is similar, which increases the bonding strength between the layers of the polycrystalline diamond layer and improves the overall impact resistance of the polycrystalline diamond composite sheet.

[0029] 2. The cobalt content near the interface of the cemented carbide matrix is ​​distributed in a gradient. The lower the cobalt content, the lower the coefficient of thermal expansion and the higher the elastic modulus. The relatively low cobalt content near the interface reduces the difference in the coefficient of thermal expansion and elastic modulus with the polycrystalline diamond layer, reduces the adverse effect of residual stress generated by high temperature and high pressure sintering on the impact resistance of the polycrystalline diamond composite sheet, and at the same time ensures the overall fracture toughness and brazingability of the cemented carbide matrix. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the particle size distribution curve of the polycrystalline diamond layer of the present invention;

[0031] Figure 2 This is a schematic diagram of the cobalt content distribution in the cemented carbide matrix of the polycrystalline diamond composite sheet of the present invention;

[0032] Figure 3This is a cross-sectional view of the polycrystalline diamond composite sheet structure of Embodiment 1 of the present invention;

[0033] Figure 4 This refers to the microhardness near the interface of the cemented carbide matrix in Embodiment 1 of the present invention;

[0034] Figure 5 This is a cross-sectional view of the polycrystalline diamond composite sheet structure of Embodiment 3 of the present invention;

[0035] Figure 6 It refers to the microhardness near the interface of the cemented carbide matrix in Embodiment 3 of the present invention. Detailed Implementation

[0036] To better illustrate the technical solution of the present invention, the following will provide a more detailed description in conjunction with the accompanying drawings and embodiments. However, the implementation of the present invention is not limited to the following embodiments.

[0037] Unless otherwise specified, in this invention, the term "surface layer" refers to the polycrystalline diamond layer away from the cemented carbide matrix; the term "transition layer" refers to the polycrystalline diamond layer between the surface layer and the cemented carbide matrix, and the transition layer may be one or more layers depending on the difference in diamond particle distribution; the term "cobalt content" refers to the mass percentage of cobalt at that location; "previous transition layer" refers to the transition layer adjacent to and closer to the surface layer; the term "major particle size" refers to the particle size of most diamond particles, and the term "secondary particle size" refers to the particle size of a small portion of diamond particles. The diamond particles in the polycrystalline diamond layer are composed of "major particle size" and "secondary particle size." The major particle size is equivalent to the skeleton of the diamond layer, and the secondary particle size is used to fill the gaps between the major particles; D10 is the particle size corresponding to a cumulative particle size distribution percentage of 10%, D50 is the particle size corresponding to a cumulative particle size distribution percentage of 50%, and D90 is the particle size corresponding to a cumulative particle size distribution percentage of 90%.

[0038] like Figure 3 As shown, the high-impact polycrystalline diamond composite sheet for oil and gas drilling provided by the present invention consists of a cemented carbide substrate 2 and a polycrystalline diamond layer 1 disposed on the cemented carbide substrate 2; wherein: as Figure 1 As shown, the polycrystalline diamond layer 1 includes a surface layer and at least one transition layer; each transition layer's diamond particles include two principal grain sizes, wherein the finer principal grain size at least partially overlaps with the principal grain size of the surface layer or the coarser principal grain size of the preceding transition layer; as shown... Figure 2 As shown, the cemented carbide substrate 2 has a cobalt gradient layer at one end near the polycrystalline diamond layer 1. The cobalt content of the cobalt gradient layer decreases in a gradient direction near the polycrystalline diamond layer 1. The cobalt content of the cobalt gradient layer at the interface adjacent to the polycrystalline diamond layer is 60wt% to 90wt% of the cemented carbide substrate outside the cobalt gradient layer.

[0039] In each layer of polycrystalline diamond layer 1, the main size diamond particles account for 75wt% to 97wt% of the total weight, and the auxiliary particle size is 1 / 30 to 1 / 2 of the main size.

[0040] Furthermore, the surface thickness of the polycrystalline diamond layer 1 is 0.5–2 mm, the total thickness of the transition layer is 0.5–3.5 mm, and the total thickness is 1.0–5.0 mm.

[0041] Furthermore, the main particle size of the polycrystalline diamond surface layer is 10–40 micrometers, and the particle size distribution curve measured by a laser particle size analyzer shows a single-peak shape, with a high particle concentration.

[0042] Furthermore, the main particle size of the transition layer is formed by mixing two particle sizes, coarse and fine, in a mass ratio of 3:1 to 0.5:1. The fine particle size is 10 to 60 micrometers, and the coarse particle size is 30 to 80 micrometers. Before mixing, the particle size distribution characteristics of each particle size are the same as those of the main particle size of the surface layer. After mixing, the particle size distribution curve is bimodal, with the fine particle size corresponding to the first peak and the coarse particle size corresponding to the second peak.

[0043] Furthermore, the particle size distribution of the first peak of the polycrystalline diamond transition layer coincides with or is similar to the particle size distribution of the surface layer; when there are two or more transition layers, the main particle size of the transition layer gradually increases from the surface layer towards the cemented carbide matrix, and the particle size distribution of the first peak of the transition layer coincides with or is similar to the particle size distribution of the second peak of the previous transition layer.

[0044] Furthermore, the cobalt content of the cemented carbide substrate is 10wt% to 16wt%. The cemented carbide substrate is placed in a carburizing atmosphere with a carbon potential of 0.1% to 1.5% for surface treatment at a temperature of 1000 to 1400°C for 60 to 240 minutes. This results in a gradient distribution of cobalt content near the interface between the cemented carbide substrate and the polycrystalline diamond layer, with the cobalt content gradually increasing from the interface towards the core, forming a cobalt gradient layer with a thickness of 0.5 to 5.0 mm. The cobalt is uniformly dispersed in the cemented carbide substrate outside the cobalt gradient layer, and the cobalt content near the interface is 60wt% to 90wt% of that in the core of the cemented carbide substrate.

[0045] The method for preparing the above-mentioned high-impact polycrystalline diamond composite sheet for oil and gas drilling provided by the present invention includes the following steps:

[0046] A cemented carbide substrate with a cobalt content of 10wt% to 16wt% is placed in a carburizing atmosphere and treated at 1000 to 1400°C for 60 to 240 minutes to form a cobalt gradient layer.

[0047] The polycrystalline diamond layer powder is subjected to high-temperature reduction to obtain purified polycrystalline diamond layer powder.

[0048] The purified polycrystalline diamond powder, cemented carbide matrix, and various assembly components are assembled internally and externally to form an external composite mold.

[0049] The outer molding die is placed into a six-sided press and sintered under vacuum, high temperature and high pressure to obtain a polycrystalline diamond composite sheet.

[0050] In some embodiments, the high-temperature reduction of the polycrystalline diamond layer powder includes: subjecting the mixed powder to high-temperature reduction purification treatment under a hydrogen atmosphere, with a treatment temperature of 600-800°C and a time of 60-120 min.

[0051] In some embodiments, vacuum high-temperature and high-pressure sintering includes: heat treatment at 900–1200°C for 60–150 min under vacuum conditions.

[0052] In some embodiments, the assembly components include carbon parts, salt parts, pyrophyllite, and conductive steel rings.

[0053] Unless otherwise specified, the raw materials and assembly components used in this invention are all commonly used raw materials and parts in the field, and the main particle size of the transition layer is obtained by conventional ball milling or ballless mixing to achieve a bimodal distribution.

[0054] Example 1

[0055] This embodiment uses a 1613 specification (15.88mm diameter, 13.21mm height) high-impact polycrystalline diamond composite sheet for oil and gas drilling. Figure 3 As shown, the structure comprises a polycrystalline diamond layer 1 and a cemented carbide substrate 2. The polycrystalline diamond layer 1 has a double-layer structure, consisting of a surface layer 11 and a transition layer 12. The total thickness of the polycrystalline diamond layer 1 is 2.5 mm, the thickness of the surface layer 11 is 1.0 mm, and the thickness of the transition layer 12 is 1.5 mm. The main particle size of the diamond micron powder in the surface layer 11 is 20–30 micrometers, accounting for 80 wt%, while the secondary particle size is 2–4 micrometers, accounting for 20 wt%. The main particle size of the transition layer 12 is a mixture of diamond particles with two particle size ranges: 50–60 micrometers and 20–30 micrometers, accounting for 50 wt% and 40 wt%, respectively. The secondary particle size is 4–6 micrometers, accounting for 10 wt%. The cemented carbide substrate has a cobalt content of 13%. It is placed in a carburizing atmosphere with a carbon potential of 0.5% and treated at 1300℃ for 60 minutes to create a continuous gradient distribution of cobalt content near the interface. Based on microhardness, the thickness of the cobalt gradient layer is approximately 1.8 mm. Figure 4As shown. During the preparation process, the mixed powder was subjected to high-temperature reduction purification treatment in a hydrogen atmosphere at a temperature of 600℃ for 60 minutes. The diamond powder, cemented carbide matrix, and metal cup that had undergone high-temperature reduction purification were then internally assembled. The assembled internal mold was then heat-treated under vacuum conditions at a temperature of 900℃ for 60 minutes. The heat-treated internal mold was then assembled with other external assembly components to form an external mold. Finally, it was placed in a six-sided press for vacuum high-temperature and high-pressure sintering at a temperature of 1600℃ and a sintering pressure of 7.8 GPa.

[0056] This high-impact polycrystalline diamond composite sheet was compared with a conventional double-layer impact-resistant composite sheet used in oil and gas drilling, such as a composite sheet with a surface layer using a 20-30 micrometer main particle size and a transition layer using a single 30-40 micrometer main particle size. Wear resistance and impact resistance were tested. The test results are shown in Table 1: Compared with the conventional double-layer impact-resistant composite sheet, the high-impact polycrystalline diamond composite sheet showed essentially the same wear resistance, but its impact resistance was improved by approximately 31%.

[0057] Table 1. Performance Comparison between High Impact-Resistant Polycrystalline Diamond Composite Sheets and Conventional Double-Layer Impact-Resistant Composite Sheets

[0058]

[0059] Example 2

[0060] This embodiment is a 1613 specification (15.88mm in diameter and 13.21mm in height) high-impact polycrystalline diamond composite sheet for oil and gas drilling. The polycrystalline diamond layer structure and thickness, and the cemented carbide matrix are the same as in Example 1. Figure 3 , Figure 4 As shown. The surface layer 11 consists of diamond microparticles with a main particle size of 15–25 micrometers, accounting for 90 wt%, and auxiliary particle size of 2–4 micrometers, accounting for 10 wt%. The transition layer 12 consists of a mixture of diamond particles with two main particle sizes: 40–60 micrometers and 15–25 micrometers, accounting for 50 wt% and 40 wt% respectively, and auxiliary particle size of 4–6 micrometers, accounting for 10 wt%. During the preparation process, the mixed powder is subjected to high-temperature reduction purification treatment in a hydrogen atmosphere at a temperature of 600℃ for 60 minutes. The diamond powder, cemented carbide matrix, and metal cup that have undergone high-temperature reduction purification are then internally assembled. The assembled internal mold is then heat-treated under vacuum conditions at a temperature of 900℃ for 60 minutes. The heat-treated internal mold is then assembled with other external assembly components to form an external mold. Finally, it is placed in a six-sided press for vacuum high-temperature and high-pressure sintering at a temperature of 1600℃ and a sintering pressure of 7.8 GPa.

[0061] The wear resistance and impact resistance of this high-impact polycrystalline diamond composite sheet were compared with those of the conventional double-layer impact-resistant composite sheet for oil and gas drilling mentioned in Example 1. The surface layer of the composite sheet uses a main particle size of 20-30 micrometers and the transition layer uses a single main particle size of 30-40 micrometers. The test results are shown in Table 2. Compared with the conventional double-layer impact-resistant composite sheet, the high-impact polycrystalline diamond composite sheet has an approximately 10% improvement in wear resistance and an approximately 26% improvement in impact resistance.

[0062] Table 2. Performance Comparison between High Impact-Resistant Polycrystalline Diamond Composite Sheets and Conventional Double-Layer Impact-Resistant Composite Sheets

[0063]

[0064] Example 3

[0065] This embodiment uses a 1613 specification (15.88mm diameter, 13.21mm height) high-impact polycrystalline diamond composite sheet for oil and gas drilling. Figure 5 As shown, the structure comprises a polycrystalline diamond layer 1 and a cemented carbide substrate 2. The polycrystalline diamond layer 1 has a three-layer structure, consisting of a surface layer 13, a transition layer 14, and a transition layer 15. The total thickness of the polycrystalline diamond layer 1 is 2.8 mm, the thickness of the surface layer 13 is 1.0 mm, and the thicknesses of the transition layers 14 and 15 are both 0.9 mm. The surface layer 13 has a main particle size of 15–25 micrometers, accounting for 80 wt%, and a secondary particle size of 4–6 micrometers, accounting for 20 wt%. The transition layer 14 has a main particle size composed of a mixture of diamond particles from two different particle size ranges: 30–40 micrometers and 15–25 micrometers, accounting for 60 wt% and 30 wt%, respectively, and a secondary particle size of 4–6 micrometers, accounting for 10 wt%. The transition layer 15 consists of a mixture of diamond particles with two different particle sizes: 40–60 micrometers and 30–40 micrometers, accounting for 45 wt% and 40 wt% respectively. The secondary particle size is 8–12 micrometers, accounting for 15 wt%. The cemented carbide matrix 2 has a cobalt content of 13%. The cemented carbide matrix is ​​placed in a carburizing atmosphere with a carbon potential of 0.5% and treated at 1300℃ for 90 min to create a continuous gradient distribution of cobalt content near the interface. Based on microhardness, the thickness of the cobalt gradient layer is approximately 2.1 mm. During the preparation process, the mixed powder is subjected to high-temperature reduction purification treatment in a hydrogen atmosphere at a temperature of 600℃ for 60 minutes. The diamond powder, cemented carbide matrix, and metal cup that have undergone high-temperature reduction purification are then internally assembled. The assembled internal mold is then heat-treated under vacuum conditions at a temperature of 900℃ for 60 minutes. The heat-treated internal mold is then assembled with other external assembly components to form an external mold. Finally, it is placed in a six-sided press for vacuum high-temperature and high-pressure sintering at a temperature of 1600℃ and a sintering pressure of 7.8 GPa.

[0066] The wear resistance and impact resistance of this high-impact polycrystalline diamond composite sheet were compared with those of the conventional double-layer impact-resistant composite sheet for oil and gas drilling mentioned in Example 1. The surface layer of the composite sheet uses a main particle size of 20-30 micrometers and the transition layer uses a single main particle size of 30-40 micrometers. The test results are shown in Table 3. Compared with the conventional double-layer impact-resistant composite sheet, the high-impact polycrystalline diamond composite sheet has an increase in wear resistance of about 23% and an increase in impact resistance of about 29%.

[0067] Table 3. Performance Comparison between High Impact-Resistant Polycrystalline Diamond Composite Sheets and Conventional Double-Layer Impact-Resistant Composite Sheets

[0068]

[0069] It should be noted that the above embodiments are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. Other implementation schemes made by those skilled in the art without departing from the technical solution of the present invention and without creative effort are all considered to be within the protection scope of the present invention.

Claims

1. A method for preparing a high-impact polycrystalline diamond composite sheet for oil and gas drilling, characterized in that, include: A cemented carbide substrate with a cobalt content of 10wt%~16wt% is placed in a carburizing atmosphere and treated at 1000~1400℃ for 60~240min to form a cobalt gradient layer. The polycrystalline diamond layer powder is subjected to high-temperature reduction to obtain purified polycrystalline diamond layer powder; the polycrystalline diamond layer includes a surface layer and at least one transition layer; the particle size distribution curve of the main particle size of the surface layer is unimodal and the particle size distribution satisfies Each transition layer of diamond particles includes two principal sizes. The fine principal size accounts for 30wt% to 60wt% of the transition layer. The distribution of the fine principal size at least partially overlaps with the distribution of the principal size of the surface layer or the distribution of the coarse principal size of the previous transition layer, and the D50 difference between the two principal sizes is 15 to 35 micrometers. The principal size of each transition layer is formed by mixing the coarse and fine sizes in a mass ratio of 3:1 to 0.5:

1. The fine principal size is 10 to 60 micrometers, and the coarse principal size is 30 to 80 micrometers. Before mixing, the particle size distribution characteristics of each size are the same as those of the principal size of the surface layer. After mixing, the particle size distribution curve is bimodal. The purified polycrystalline diamond powder, cemented carbide matrix, and various assembly components are assembled internally and externally to form an external composite mold. The outer molding die is placed in a six-sided press and sintered under vacuum, high temperature and high pressure at a pressure of 7.8 GPa to obtain a polycrystalline diamond composite sheet.

2. The method for preparing the high-impact polycrystalline diamond composite sheet for oil and gas drilling according to claim 1, characterized in that: The polycrystalline diamond layer consists of a surface layer and a first transition layer; the principal particle size of the surface layer is A1, and the principal particle sizes of the first transition layer are B1 and C1, where A1 and B1 are both smaller than C1, and A1 and B1 at least partially overlap.

3. The method for preparing the high-impact polycrystalline diamond composite sheet for oil and gas drilling according to claim 1, characterized in that: The polycrystalline diamond layer consists of a surface layer, a first transition layer, and a second transition layer. The principal particle size of the surface layer is A2, the principal particle sizes of the first transition layer are B2 and C2, and the diamond particles of the second transition layer include principal particle sizes D and E. A2 and B2 are both smaller than C2, C2 and D are both smaller than E, and A2 and B2 at least partially overlap, and C2 and D at least partially overlap.

4. The method for preparing the high-impact polycrystalline diamond composite sheet for oil and gas drilling according to claim 1, characterized in that: The cobalt content of the cemented carbide substrate outside the cobalt gradient layer is 10wt%~16wt%.

5. The method for preparing the high-impact polycrystalline diamond composite sheet for oil and gas drilling according to claim 1, characterized in that: The thickness of the cobalt gradient layer is 0.5~5.0 mm.

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