A highly wear-resistant polycrystalline diamond composite sheet

Abstract

A highly wear-resistant polycrystalline diamond composite sheet comprises a polycrystalline diamond layer and a cemented carbide substrate located below the polycrystalline diamond layer. The polycrystalline diamond layer is a coarse-grained polycrystalline diamond layer, and fine-grained polycrystalline diamond columns with a smaller particle size than the polycrystalline diamond layer are axially arranged inside the coarse-grained polycrystalline diamond layer. The outer polycrystalline diamond layer has a coarse particle size, which, as an impact toughness layer, ensures impact toughness in the initial stage of drilling operations, prevents product tooth breakage, and reduces the damage rate. The inner fine-grained polycrystalline diamond columns have a fine particle size, which is finer than the polycrystalline diamond layer. As a wear-resistant layer, the design ensures that the wear resistance of the polycrystalline diamond composite sheet remains consistent from the beginning of use to the completion of the task indicators, thereby improving the overall performance of the product.

Description

Technical Field

[0001] The present invention relates to the field of polycrystalline diamond composite sheets, and more particularly to a highly wear-resistant polycrystalline diamond composite sheet. Background Art

[0002] Polycrystalline diamond compact (PDC) is a new functional material made by sintering diamond powder and a cemented carbide matrix under high temperature and high pressure (HTHP) conditions. It generally has a cylindrical structure and combines the high hardness, high wear resistance and thermal conductivity of diamond with the strength and impact toughness of cemented carbide. It is an ideal material for manufacturing cutting tools, drilling bits and other wear-resistant tools.

[0003] With the in-depth development of geological drilling in recent years, drilling depths have increased, and the requirements for the comprehensive performance of geological drilling materials have become increasingly stringent. As drilling depths increase, the operating conditions of polycrystalline diamond compact (PCD) drill bits become increasingly complex, and the requirements for the wear resistance and impact toughness of the compact are also becoming increasingly stringent. Many PCD composite layers experience wear of up to one-third or even more. Therefore, improving the wear resistance of the PCD composite layer has become a key factor in improving the drilling performance of drill bits. In addition, due to the high drill bit speeds and the harsh and complex geological environment during drilling operations, the PCD composite layer must also have sufficient impact toughness to prevent cracking and direct failure at the beginning of drilling. However, from the perspective of the PCD layer, to ensure good wear resistance and thermal stability, the composite layer particle size must be fine, while to ensure good impact toughness, the composite layer particle size must be coarse. This creates a contradiction in the selection of the PCD composite layer particle size when producing PCD composites. At the same time, during the synthesis process of the polycrystalline diamond composite sheet, the pressure transmission method from the outside to the inside also leads to a significant pressure difference between the inside and the outer surface of the composite sheet, resulting in the internal wear resistance of the polycrystalline diamond composite sheet being significantly lower than the wear resistance of the outer surface. Summary of the Invention

[0004] In response to the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a highly wear-resistant polycrystalline diamond composite sheet to solve the problem of setting the particle size of the polycrystalline diamond composite layer while ensuring the comprehensive performance of the polycrystalline diamond layer such as wear resistance, thermal stability, and impact toughness, as proposed in the above-mentioned background technology.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a highly wear-resistant polycrystalline diamond composite sheet, comprising a polycrystalline diamond layer and a cemented carbide substrate located below the polycrystalline diamond layer, wherein the polycrystalline diamond layer is a coarse-grained polycrystalline diamond layer, and fine-grained polycrystalline diamond columns with a particle size smaller than that of the polycrystalline diamond layer are axially arranged inside the coarse-grained polycrystalline diamond layer.

[0006] The fine-grained polycrystalline diamond column is a cylinder, and a transition layer is provided between the fine-grained polycrystalline diamond column and the polycrystalline diamond layer. In the transition layer from the fine-grained polycrystalline diamond column to the polycrystalline diamond layer, the small-grained polycrystalline diamond gradually decreases and the large-grained polycrystalline diamond gradually increases.

[0007] The thickness of the transition layer is 0.3-0.8 mm.

[0008] The fine-grained polycrystalline diamond column is located in the center of the polycrystalline diamond layer.

[0009] The diameter of the fine-grained polycrystalline diamond column is 0.5-0.8 times the diameter of the polycrystalline diamond layer.

[0010] The fine-grained polycrystalline diamond column (8) can be configured as a hollow fine-grained polycrystalline diamond cylinder, which is coaxial with the polycrystalline diamond layer (2) and diffuses in the radial direction.

[0011] The diameter of the hollow fine-grained polycrystalline diamond column (8) is 0.1-0.5 times the diameter of the polycrystalline diamond layer, and preferably the diameters are 0.4 times and 0.2 times, respectively, from large to small.

[0012] The height of the fine-grained polycrystalline diamond column (4) and the hollow fine-grained polycrystalline diamond column (8) is 0.5-1 times the height of the polycrystalline diamond layer.

[0013] The particle size ratio of the polycrystalline diamond micropowder of the fine-grained polycrystalline diamond column (4) and the hollow fine-grained polycrystalline diamond column (8) is: 2-4 μm accounts for 10%, 4-8 μm accounts for 20%, 16-26 μm accounts for 60%, and 30-40 μm accounts for 10%; the particle size ratio of the polycrystalline diamond micropowder of the coarse-grained polycrystalline diamond layer is: 4-8 μm accounts for 5%, 12-22 μm accounts for 15%, 25-40 μm accounts for 60%, 40-60 μm accounts for 15%, and 60-80 μm accounts for 5%.

[0014] The polycrystalline diamond layer is subjected to deep decobalting treatment, and the decobalting depth is greater than 700 μm.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. The outer polycrystalline diamond layer has a coarse grain size. As an impact toughness layer, it ensures impact toughness in the initial stage of drilling operations, prevents tooth breakage in the product, and reduces the damage rate. The inner fine-grained polycrystalline diamond column has a fine grain size, which is finer than the polycrystalline diamond layer. As a wear-resistant layer, it ensures that the wear resistance of the polycrystalline diamond composite sheet remains consistent from the beginning of use to the completion of the task indicators, thereby improving the overall performance of the product.

[0017] 2. According to laboratory test results, the impact toughness remains unchanged, the wear from the outer surface to the center is reduced from the original 30% to 10%, and the wear resistance is improved by 20% compared with previous products.

[0018] 3. Deep decobalting of the polycrystalline diamond layer (above 700um) can improve the thermal stability of the product, and chamfering the upper end surface of the polycrystalline diamond layer can improve the impact toughness of the composite sheet during use.

[0019] 4. It ensures the stability of drilling quality, increases drilling depth, reduces drilling costs, reduces drill bit damage, and improves operating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the cross-sectional structure of a polycrystalline diamond composite sheet. Figure 1 .

[0021] Figure 2 This is a schematic diagram of the cross-sectional structure of a polycrystalline diamond composite sheet. Figure 2 .

[0022] Figure 3 This is a schematic diagram of the cross-sectional structure of a polycrystalline diamond composite sheet. Figure 3 .

[0023] Figure 4 This is a schematic diagram of the cross-sectional structure of a polycrystalline diamond composite sheet. Figure 4 .

[0024] Figure 5 The assembly process of specific embodiment 4 Figure 1 .

[0025] Figure 6 The assembly process of specific embodiment 4 Figure 2 .

[0026] Figure 7 The assembly process of specific embodiment 4 Figure 3 .

[0027] Figure 8 The assembly process of specific embodiment 4 Figure 4 .

[0028] Figure 9 It is a top view of the polycrystalline diamond composite sheet of specific embodiment 4.

[0029] Among them, 1. cemented carbide substrate; 2. polycrystalline diamond layer; 3. transition layer; 4. fine-grained polycrystalline diamond cylinder; 5. hollow cylinder; 6. metal bottom cup; 7. metal cap cup; 8. hollow fine-grained polycrystalline diamond cylinder. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] A highly wear-resistant polycrystalline diamond composite sheet comprises a polycrystalline diamond layer 2 and a cemented carbide substrate 1 located below the polycrystalline diamond layer. The polycrystalline diamond layer 2 is a coarse-grained polycrystalline diamond layer, and fine-grained polycrystalline diamond columns 4 with a smaller particle size than the polycrystalline diamond layer are axially arranged inside the coarse-grained polycrystalline diamond layer.

[0032] The fine-grained polycrystalline diamond column 4 is cylindrical, and a transition layer 3 is set between the fine-grained polycrystalline diamond column 4 and the polycrystalline diamond layer 2. In the transition layer from the fine-grained polycrystalline diamond column 4 to the polycrystalline diamond layer 2, the small-grained polycrystalline diamond gradually decreases and the large-grained polycrystalline diamond gradually increases.

[0033] The thickness of the transition layer 3 is 0.3-0.8 mm. The provision of the transition layer 3 is conducive to a tighter and stronger combination of two polycrystalline diamonds of different particle sizes in the polycrystalline diamond composite layer.

[0034] The fine-grained polycrystalline diamond column 4 is located in the center of the polycrystalline diamond layer 2 .

[0035] The diameter of the fine-grained polycrystalline diamond column 4 is 0.5-0.8 times the diameter of the polycrystalline diamond layer.

[0036] The fine-grained polycrystalline diamond column (8) can be configured as a hollow fine-grained polycrystalline diamond cylinder, which is coaxial with the polycrystalline diamond layer (2) and diffuses in the radial direction.

[0037] The diameter of the hollow fine-grained polycrystalline diamond column (8) is 0.1-0.5 times the diameter of the polycrystalline diamond layer, and preferably the diameters are 0.4 times and 0.2 times, respectively, from large to small.

[0038] The height of the fine-grained polycrystalline diamond column (4) and the hollow fine-grained polycrystalline diamond column (8) is 0.5-1 times the height of the polycrystalline diamond layer.

[0039] The particle size ratio of the polycrystalline diamond micropowder of the fine-grained polycrystalline diamond column (4) and the hollow fine-grained polycrystalline diamond column (8) is: 2-4 μm accounts for 10%, 4-8 μm accounts for 20%, 16-26 μm accounts for 60%, and 30-40 μm accounts for 10%; the particle size ratio of the polycrystalline diamond micropowder of the coarse-grained polycrystalline diamond layer is: 4-8 μm accounts for 5%, 12-22 μm accounts for 15%, 25-40 μm accounts for 60%, 40-60 μm accounts for 15%, and 60-80 μm accounts for 5%.

[0040] The polycrystalline diamond layer 2 is subjected to a deep decobalting treatment, with the decobalting depth being greater than 700 μm. Specific embodiment 1

[0042] like Figure 1 It is an assembly structure of a highly wear-resistant polycrystalline diamond composite sheet. During assembly, the polycrystalline diamond composite layer is first assembled in a metal bottom cup, then a cemented carbide substrate is placed, and finally a metal cap cup is placed on the top of the cemented carbide substrate.

[0043] When assembling the polycrystalline diamond composite layer, a hollow cylinder is first placed inside a metal base cup. The wall thickness of the hollow cylinder is equal to the thickness of the transition layer, generally 0.5mm, and the central axis of the hollow cylinder coincides with the central axis of the metal base cup. Coarse-grained polycrystalline diamond micropowder is placed in the space formed by the inside of the metal base cup and the outside of the hollow cylinder. Fine-grained polycrystalline diamond micropowder is placed on the hollow inner circle of the bottom surface of the hollow cylinder, and a certain amount of micropowder is reserved. The reserved amount of coarse-grained polycrystalline diamond micropowder and fine-grained polycrystalline diamond micropowder each accounts for half, which is equal to half of the volume of the transition layer after leveling. The volume of the transition layer is equal to the area of ​​the bottom ring multiplied by the height of the transition layer. The hollow cylinder is then lifted upward at a uniform speed, and the two polycrystalline diamond micropowders of different particle sizes mix at the boundary to form the transition layer. Use a T-shaped hammer to flatten it. The thickness of the flattened surface is equal to the thickness of the polycrystalline diamond layer and also equal to the thickness of the polycrystalline diamond column. Then put it into the carbide substrate and cover it with a metal cap cup, or cover it with a metal cap cup after shaping. Specific embodiment 2

[0045] like Figure 2 This is another assembly structure of highly wear-resistant polycrystalline diamond composite sheets. During assembly, the polycrystalline diamond composite layer is first assembled in the metal bottom cup, then the cemented carbide substrate is placed, and finally the metal cap cup is placed on the top of the cemented carbide substrate.

[0046] When assembling the polycrystalline diamond composite layer, a hollow cylinder is first placed in the metal bottom cup. The wall thickness of the hollow cylinder is equal to the thickness of the transition layer, generally 0.5 mm, and the central axis of the hollow cylinder coincides with the central axis of the metal bottom cup. Coarse-grained polycrystalline diamond powder is placed in the space formed by the inner side of the metal bottom cup and the outer side of the hollow cylinder, and fine-grained polycrystalline diamond powder is placed on the hollow inner circle of the bottom surface of the hollow cylinder, and a certain amount of powder is reserved. The reserved amount of coarse-grained polycrystalline diamond powder and fine-grained polycrystalline diamond powder is half each, which is equal to half of the volume of the transition layer after leveling. The volume of the transition layer is equal to the area of ​​the bottom ring multiplied by the height of the transition layer. Then the hollow cylinder is lifted upward at a uniform speed, and the two polycrystalline diamond powders of different particle sizes are mixed together at the boundary to form a transition layer. The transition layer is flattened with a T-shaped hammer. The thickness at this time is the required thickness of the polycrystalline diamond column. Then the coarse-grained polycrystalline diamond powder layer is added and flattened with a T-shaped hammer. The flattened thickness is the thickness of the polycrystalline diamond composite layer. Finally, the cemented carbide substrate is placed and covered with a metal cap cup, or covered with a metal cap cup after shaping. Specific embodiment 3

[0048] like Figure 3 This is another assembly structure of highly wear-resistant polycrystalline diamond composite sheets. During assembly, the polycrystalline diamond composite layer is first assembled in the metal bottom cup, then the cemented carbide substrate is placed, and finally the metal cap cup is placed on the top of the cemented carbide substrate.

[0049] When assembling the polycrystalline diamond composite layer, first place three hollow cylinders in the metal bottom cup. The wall thickness of the hollow cylinder is equal to the thickness of the transition layer, generally 0.5mm. The hollow cylinders are distributed radially outward from the center of the metal bottom cup. The outer diameter of the bottom surface of the hollow cylinder in the center is 0.4 times the diameter of the inner wall of the metal bottom cup, the outer diameter of the bottom surface of the hollow cylinder in the middle is 0.6 times the diameter of the inner wall of the metal bottom cup, and the outer diameter of the bottom surface of the outermost hollow cylinder is 0.8 times the diameter of the inner wall of the metal bottom cup. Fine-grained polycrystalline diamond micropowder is placed inside the hollow cylinder in the center, coarse-grained polycrystalline diamond micropowder is placed between the two hollow cylinders in the center and the middle, fine-grained polycrystalline diamond micropowder is placed between the two hollow cylinders in the middle and the outermost end, and coarse-grained polycrystalline diamond micropowder is placed between the outermost hollow cylinder and the inner wall of the metal bottom cup; that is, along the radial direction of the metal bottom cup, the fine-grained polycrystalline diamond micropowder and the coarse-grained polycrystalline diamond micropowder are distributed in a ring shape. During assembly, a certain amount of micropowder must be reserved. The reserved amount of coarse-grained polycrystalline diamond micropowder and fine-grained polycrystalline diamond micropowder accounts for half each, which is equal to half of the volume of the transition layer after leveling. The volume of the transition layer is equal to the area of ​​the bottom ring multiplied by the height of the transition layer. Then, three hollow cylinders are lifted upward at a uniform speed. The two polycrystalline diamond micropowders of different particle sizes are mixed together at the boundary to form a transition layer. Use a T-shaped hammer to flatten it. The thickness of the flattened layer is equal to the thickness of the polycrystalline diamond composite layer and also equal to the thickness of the polycrystalline diamond column. Then put in the carbide substrate and cover it with a metal cap cup, or cover it with a metal cap cup after shaping. Specific embodiment 4

[0051] like Figure 4 This is another assembly structure of highly wear-resistant polycrystalline diamond composite sheets. During assembly, the polycrystalline diamond composite layer is first assembled in the metal bottom cup, then the cemented carbide substrate is placed, and finally the metal cap cup is placed on the top of the cemented carbide substrate.

[0052] like Figure 5-8When assembling the polycrystalline diamond composite layer, first place three hollow cylinders in the metal bottom cup. The wall thickness of the hollow cylinder is equal to the thickness of the transition layer, generally 0.5mm. The hollow cylinders are distributed radially outward from the center of the metal bottom cup. The outer diameter of the bottom surface of the hollow cylinder in the center is 0.4 times the diameter of the inner wall of the metal bottom cup, the outer diameter of the bottom surface of the hollow cylinder in the middle is 0.6 times the diameter of the inner wall of the metal bottom cup, and the outer diameter of the bottom surface of the outermost hollow cylinder is 0.8 times the diameter of the inner wall of the metal bottom cup. Fine-grained polycrystalline diamond micropowder is placed inside the hollow cylinder in the center, coarse-grained polycrystalline diamond micropowder is placed between the two hollow cylinders in the center and the middle, fine-grained polycrystalline diamond micropowder is placed between the two hollow cylinders in the middle and the outermost end, and coarse-grained polycrystalline diamond micropowder is placed between the outermost hollow cylinder and the inner wall of the metal bottom cup; that is, along the radial direction of the metal bottom cup, the fine-grained polycrystalline diamond micropowder and the coarse-grained polycrystalline diamond micropowder are distributed in a ring shape. During assembly, a certain amount of micropowder must be reserved. The reserved amount of coarse-grained polycrystalline diamond micropowder and fine-grained polycrystalline diamond micropowder is half each, which is equal to half of the volume of the transition layer after leveling. The volume of the transition layer is equal to the area of ​​the bottom ring multiplied by the height of the transition layer. Then lift the hollow cylinder upward at a uniform speed. The two polycrystalline diamond micropowders of different particle sizes are mixed together at the boundary to form a transition layer. Use a T-shaped hammer to flatten it. The thickness at this time is the required thickness of the polycrystalline diamond column. Then add the coarse-grained polycrystalline diamond micropowder layer and use a T-shaped hammer to flatten it. The flattened thickness is the thickness of the polycrystalline diamond composite layer. Finally, put in the cemented carbide substrate and cover it with a metal cap cup, or cover it with a metal cap cup after shaping.

[0053] In Specific Examples 3 and 4, the annular fine-grained polycrystalline diamond powder and coarse-grained polycrystalline diamond powder distributed from the inside out can be arranged into four different particle sizes, arranged from the inside out: a relatively fine polycrystalline diamond powder layer, a fine polycrystalline diamond powder layer, a coarse polycrystalline diamond powder layer, and a relatively coarse polycrystalline diamond powder layer. These are not listed one by one.

[0054] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

Claims

1. A highly wear-resistant polycrystalline diamond composite sheet comprising a polycrystalline diamond layer (2) and a cemented carbide substrate (1) located below the polycrystalline diamond layer, characterized in that: The polycrystalline diamond layer (2) is a coarse-grained polycrystalline diamond layer, and a fine-grained polycrystalline diamond column (4) with a smaller particle size than the polycrystalline diamond layer is axially arranged inside the coarse-grained polycrystalline diamond layer; the fine-grained polycrystalline diamond column (4) is a cylinder, and a transition layer (3) is arranged between the fine-grained polycrystalline diamond column (4) and the polycrystalline diamond layer (2); in the transition layer from the fine-grained polycrystalline diamond column (4) to the polycrystalline diamond layer 2, the small-grained polycrystalline diamond gradually decreases and the large-grained polycrystalline diamond gradually increases; the thickness of the transition layer (3) is 0.3-0.8 mm; the fine-grained polycrystalline diamond column (4) is located in the center of the polycrystalline diamond layer (2); the diameter of the fine-grained polycrystalline diamond column (4) is 0.5-0.8 times the diameter of the polycrystalline diamond layer, When assembling the polycrystalline diamond composite layer, first place a hollow cylinder in the metal bottom cup. The wall thickness of the hollow cylinder is equal to the thickness of the transition layer, which is selected as 0.5mm. The central axis of the hollow cylinder coincides with the central axis of the metal bottom cup. Coarse-grained polycrystalline diamond micropowder is placed in the space formed by the inner side of the metal bottom cup and the outer side of the hollow cylinder. Fine-grained polycrystalline diamond micropowder is placed on the hollow inner circle of the bottom surface of the hollow cylinder. Then, the hollow cylinder is lifted upward at a uniform speed. The two polycrystalline diamond micropowders of different particle sizes are mixed together at the boundary to form a transition layer. Use a T-shaped hammer to flatten it. The flattened thickness is equal to the thickness of the polycrystalline diamond layer and the thickness of the polycrystalline diamond column. Then, place the cemented carbide substrate and cover it with a metal cap cup, or cover it with a metal cap cup after shaping.

2. The highly wear-resistant polycrystalline diamond compact according to claim 1, characterized in that: The fine-grained polycrystalline diamond column (4) can be configured as a hollow fine-grained polycrystalline diamond column (8), wherein the hollow fine-grained polycrystalline diamond column (8) is coaxial with the polycrystalline diamond layer (2) and diffuses in the radial direction.

3. The highly wear-resistant polycrystalline diamond compact according to claim 2, characterized in that: The diameter of the hollow fine-grained polycrystalline diamond column (8) is 0.1-0.5 times the diameter of the polycrystalline diamond layer.

4. The highly wear-resistant polycrystalline diamond compact according to claim 3, characterized in that: The diameter of the hollow fine-grained polycrystalline diamond column (8) is 0.4 times or 0.2 times the diameter of the polycrystalline diamond layer.

5. The highly wear-resistant polycrystalline diamond compact according to any one of claims 1 to 4, characterized in that: The height of the fine-grained polycrystalline diamond column (4) and the hollow fine-grained polycrystalline diamond column (8) is 0.5-1 times the height of the polycrystalline diamond layer.

6. The highly wear-resistant polycrystalline diamond compact according to claim 5, characterized in that: The particle size ratio of the polycrystalline diamond micropowder of the fine-grained polycrystalline diamond column (4) and the hollow fine-grained polycrystalline diamond column (8) is: 2-4 μm accounts for 10%, 4-8 μm accounts for 20%, 16-26 μm accounts for 60%, and 30-40 μm accounts for 10%; the particle size ratio of the polycrystalline diamond micropowder of the coarse-grained polycrystalline diamond layer is: 4-8 μm accounts for 5%, 12-22 μm accounts for 15%, 25-40 μm accounts for 60%, 40-60 μm accounts for 15%, and 60-80 μm accounts for 5%.

7. The highly wear-resistant polycrystalline diamond compact according to claim 1, characterized in that: The polycrystalline diamond layer (2) is subjected to a deep decobalting treatment, and the decobalting depth is greater than 700 μm.

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