Diamond compact and preparation method and application thereof

Abstract

The invention belongs to the technical field of superhard composite materials, and relates to a diamond compact and a preparation method and application thereof. The preparation method comprises a vacuum packaging step of a metal material cup, and the vacuum packaging step comprises the steps that a hard alloy matrix and diamond powder are packaged in the metal material cup formed by sleeving an inner cup component and an outer cup component, and the metal material cup is overturned and placed; in a vacuum environment, the metal material cup is heated for impurity removal; in a vacuum environment, a first laser beam is adopted to preheat the splicing area of the metal material cup; and in the vacuum environment, a second laser beam is adopted for welding the preheated splicing area. Through the vacuum packaging step, vacuum sealing of the diamond powder and the hard alloy matrix is achieved, sufficient formation of strong covalent bonding of diamonds in the subsequent sintering process is guaranteed, and therefore the comprehensive performance of the diamond compact is remarkably improved. The wear resistance of the diamond compact is improved by more than 16%, and the impact toughness is improved by more than 26%.

Description

Technical Field

[0001] This invention belongs to the field of superhard composite materials technology, and relates to a diamond composite sheet, its preparation method and application. Background Technology

[0002] Diamond composite (PDC) is a composite superhard material made by sintering diamond powder and cemented carbide matrix under ultra-high pressure (5~8GPa) and ultra-high temperature (1400~1800℃). It combines the high hardness of diamond with the impact toughness of cemented carbide and is widely used in oil drilling, cutting tools and other fields.

[0003] In the fabrication of diamond composites (PDCs), a clean metal cup is first used as a container to orderly assemble micron-sized diamond powder with a cemented carbide matrix, followed by sintering under high temperature and pressure. However, the unencapsulated metal cup continuously absorbs impurities such as gases, moisture, and dust from the environment, which then spread between the diamond powder particles. Under high temperature and pressure, these impurities hinder diamond-diamond bonding, severely affecting the sintering quality of the PDC and consequently significantly impacting its performance. In recent years, some researchers have proposed adding solder and flow-blocking agents to the gaps between the metal cups and using vacuum brazing to encapsulate them. However, this method introduces additional impurities and has a limited success rate. Furthermore, the diamond powder inside the metal cup is passively heated, resulting in partial graphitization, which also affects the performance of the finished product. Summary of the Invention

[0004] This invention provides a diamond composite sheet, its preparation method, and its application, to solve the problem in related technologies where metal cup encapsulation during the preparation of diamond composite sheets easily introduces foreign impurities that affect the performance of the diamond composite sheet.

[0005] The technical solution provided by this invention is as follows: In a first aspect, the present invention provides a method for preparing a diamond composite sheet, the method comprising a vacuum sealing step of a metal cup, the vacuum sealing step comprising: The cemented carbide matrix and diamond powder are encapsulated in a metal cup formed by fitting an inner cup component and an outer cup component together, and the metal cup is then flipped over and placed. The metal cup is heated to remove impurities in a vacuum environment; In a vacuum environment, the splicing area of ​​the metal cup is preheated using a first laser beam; In a vacuum environment, a second laser beam is used to weld the preheated splicing area to obtain a packaged metal cup.

[0006] In some specific embodiments of the present invention, the wall thickness of both the inner cup component and the outer cup component is 0.12~0.5mm, the inner diameter of the inner cup component is 8~25mm, and the inner diameter of the outer cup component is 8.32~26.1mm.

[0007] In some specific embodiments of the present invention, the particle size of the diamond powder is 0.5~50μm.

[0008] In some specific embodiments of the present invention, the heating temperature is 700~1200℃, and the vacuum environment pressure is 1×10⁻⁶. -3 ~1×10 -5 Pa.

[0009] In some specific embodiments of the present invention, the power of the first laser beam is 50~150W, the spot diameter is 1.5~2.0mm, the laser scanning speed is 10~15mm / s, and the vacuum environment pressure is 1×10⁻⁶. -3 ~1×10 -5 Pa.

[0010] In some specific embodiments of the present invention, the power of the second laser beam is 200~600W, the spot diameter is 0.1~0.3mm, and the laser scanning speed is 60~120mm / s.

[0011] In some specific embodiments of the present invention, the inner cup component and the outer cup component are independently selected from one or more materials selected from zirconium, niobium, molybdenum, and tantalum.

[0012] In some specific embodiments of the present invention, the preheating time is 5 to 30 minutes.

[0013] Secondly, the present invention provides a diamond composite sheet obtained by the above preparation method.

[0014] Thirdly, the present invention provides an application of the diamond composite sheet obtained by the above preparation method in the fields of oil drilling and cutting tools.

[0015] The beneficial effects of the present invention include at least the following: This invention achieves a vacuum seal between diamond powder and the cemented carbide matrix through a vacuum encapsulation step, effectively preventing impurities from entering and ensuring the full formation of strong covalent bonds between diamonds during subsequent sintering, thereby significantly improving the overall performance of the diamond composite sheet. This results in a wear resistance increase of over 16% and an impact toughness increase of over 26% for the diamond composite sheet. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the metal cup of the present invention; wherein, 10 is diamond powder; 11 is cemented carbide matrix; 12 is inner cup component; and 13 is outer cup component.

[0018] Figure 2 This is a flowchart of the vacuum sealing steps for the metal cup of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0020] This invention provides a method for preparing diamond composite sheets, including a metal cup encapsulation step, thereby improving the overall performance of the diamond composite sheets.

[0021] See the schematic diagram of the diamond composite sheet metal cup. Figure 1 It includes diamond powder 10, cemented carbide matrix 11, inner cup component 12, and outer cup component 13.

[0022] See Figure 1 As shown, the diamond powder 10 can be formed by sequentially filling one, two or three layers of powder, with each layer having a particle size range of 0.5 to 50 μm, and each layer can be obtained by ball milling one or more powders of different particle sizes.

[0023] In some specific embodiments of the present invention, the particle size distribution of diamond powder is between 0.5 and 50 μm, which can be achieved by different particle size combinations, such as using 40 wt% of 20-30 μm, 50 wt% of 10-15 μm and 10 wt% of 1-2 μm; it can also be adjusted according to needs, such as selecting different proportions of 30-40 μm, 5-10 μm or 4-8 μm particle size ranges for combination.

[0024] In some specific embodiments of the present invention, the cemented carbide matrix is ​​cylindrical. The cemented carbide matrix is ​​prepared by powder metallurgy using high-hardness carbide powder and a metal binder, and is widely used in cutting tools and wear-resistant parts. The cemented carbide mainly consists of two parts: a hardening phase and a binder metal. The hardening phase is tungsten carbide (WC), which has extremely high hardness and wear resistance, with a melting point above 2870°C. The binder is metallic cobalt (Co), which binds the tungsten carbide particles together to form a robust alloy matrix.

[0025] See Figure 1 As shown, both the inner cup component 12 and the outer cup component 13 are cylindrical structures with one open end. In some specific embodiments of the present invention, the inner cup component 12 is placed with the open end facing upward; a cemented carbide substrate 11 is filled into the bottom of the inner cup component 12; diamond powder 10 is filled and spread evenly on the upper surface of the cemented carbide substrate 11, and the top surface of the diamond powder 10 is controlled not to be higher than the opening edge of the inner cup component 12; the outer cup component 13 is fitted onto the outside of the inner cup component 12 with the open end facing downward, so that the bottom of the outer cup component 13 is in contact with the top surface of the diamond powder 10.

[0026] See Figure 1 As shown, the wall thickness of both the inner cup component 12 and the outer cup component 13 is 0.12~0.5mm. In some specific embodiments of the present invention, the thicknesses of the two components are consistent. The inner diameter of the inner cup component 12 is 8~25mm, and the inner diameter of the outer cup component 13 is 0.08~0.1mm larger than the outer diameter of the inner cup component 12, so that the outer cup component 13 completely encloses the inner cup component 12. In other specific embodiments of the present invention, the thicknesses of the inner cup component 12 and the outer cup component 13 may also be different.

[0027] See Figure 1 As shown, the inner cup component 12 is made of one or more of zirconium, niobium, molybdenum, and tantalum, and the outer cup component 13 is made of one or more of zirconium, niobium, molybdenum, and tantalum. On the one hand, zirconium, niobium, molybdenum, and tantalum are refractory metals with melting points exceeding 2000℃, while the synthesis temperature of diamond composite sheets is 1400-1800℃. Therefore, the metal cup will not soften or deform during the high-temperature and high-pressure synthesis process, and it also has good corrosion resistance and chemical inertness, so it will not react with diamond powder 10 and cause pollution. On the other hand, refractory metals can absorb gases at high temperatures through surface adsorption and lattice dissolution, effectively reducing the risk of explosion during high-temperature and high-pressure synthesis.

[0028] In some embodiments of the present invention, the inner cup component 12 and the outer cup component 13 are made of the same refractory metal. In other embodiments, the inner cup component 12 and the outer cup component 13 may be made of different refractory metals.

[0029] See Figure 2 As shown, in some specific embodiments of the present invention, "encapsulating a cemented carbide substrate and diamond powder in a metal cup formed by fitting an inner cup component and an outer cup component together, and then flipping the metal cup over" includes: placing the inner cup component 12 with its open end facing upwards; filling the bottom of the inner cup component 12 with a cemented carbide substrate 11; filling and spreading diamond powder 10 on the upper surface of the cemented carbide substrate 11, and controlling that the top surface of the diamond powder 10 is not higher than the opening edge of the inner cup component 12; fitting the outer cup component 13 with its open end facing downwards onto the outside of the inner cup component 12, such that the bottom of the outer cup component 13 contacts the top surface of the diamond powder 10, and flipping it over so that the splicing area between the inner cup component 12 and the outer cup component 13 faces upwards. Since the laser output head of the laser welding equipment is located above the worktable and the laser beam is processed from top to bottom, the metal cup needs to be flipped so that the splicing area of ​​the inner cup component 12 and the outer cup component 13 faces upward, thereby ensuring that the laser beam can directly and accurately act on the area to be welded.

[0030] See Figure 2 As shown, in some specific embodiments of the present invention, "heating and removing impurities from the metal cup under vacuum conditions" includes: simultaneously placing one or more assembled metal cups into a heat treatment furnace, first performing a vacuuming process, and achieving a vacuum degree of 1×10⁻⁶ in the working chamber. -3 ~1×10 -5 When Pa, restart the heating program, raising the temperature to 700~1200℃, and then hold for 30~120 minutes. This step can remove volatile gaseous impurities, including water vapor, oil vapor, and carbon dioxide, as well as easily volatile metallic impurities, including zinc, magnesium, manganese, aluminum, chromium, and other metal elements with high vapor pressure, which will evaporate and be removed under high temperature and vacuum. It can also remove organic pollutants, such as hydrocarbons, which are decomposed into small molecule gases such as carbon monoxide and carbon dioxide at high temperature and removed. Polymers are melted or oxidized and decomposed at 300~500℃.

[0031] See Figure 2 As shown, in some specific embodiments of the present invention, "placing the heated and impurity-removed metal cup into the laser welding equipment and preheating the metal cup using a laser beam" includes: simultaneously placing one or more heated and impurity-removed metal cups into the laser welding equipment, first performing a vacuuming process, and achieving a vacuum degree of 1×10⁻⁶ in the working chamber. -3 ~1×10 -5Next, a preheating process is performed: a 1064nm laser beam is used to preheat the metal cup. The preheating power is set to 50~150W, and the spot diameter is set to 1.5~2.0mm. Using lower power and a larger spot diameter reduces energy density, avoids burn-through, and improves temperature uniformity. The laser scanning speed is 10~15mm / s; too fast a speed will result in insufficient preheating, while too slow a speed may cause local overheating. The defocusing amount is +0.8~+1.2mm. Positive defocusing reduces surface energy density and is suitable for preheating thin-walled materials. The laser beam uses a spiral scanning path to ensure uniform heating of the entire surface of the metal cup. Following the above vacuum sealing steps for the metal cup, the preheating temperature can reach 300~600℃, and the preheating time is 5~30min. During the preheating process, the inner cup component 12 and the outer cup component 13 can undergo thermal expansion, which can reduce the initial gap of 0.08~0.1mm at the splice to within 0.02mm. This can reduce the risk of incomplete fusion, reduce the thermal stress gradient, reduce welding deformation and cold cracking tendency, avoid local expansion and warping, improve welding efficiency, and significantly improve the weld formation quality.

[0032] See Figure 2 As shown, in some specific embodiments of the present invention, "laser welding of the cup lid seam is completed in a vacuum environment to obtain an encapsulated metal cup" includes: using a laser beam with a wavelength of 1064nm for welding, which has a high absorption rate for metal materials and is beneficial for energy coupling. On the one hand, since the metal cup has a thin wall and its material is a refractory metal with a high melting point and high thermal conductivity, the laser power is selected to be 200~600W; on the other hand, to address the problem of heat accumulation in thin-walled refractory metal cups, and considering that a vacuum environment can significantly suppress the generation of metal vapor plumes, the laser scanning speed is set to 60~120mm / s to control heat input and prevent burn-through and deformation. Simultaneously, to match the tiny assembly gap of less than 0.02mm after preheating, the spot diameter is focused to 0.1~0.3mm to ensure that the laser energy is precisely applied to the welding area. Using the above parameters, the laser beam is rotated and welded 360° along the splicing area of ​​each metal cup sequentially, achieving the encapsulation of the metal cup in a vacuum environment. The principle behind this process is that when a high-energy laser beam acts on the splicing area of ​​the metal cup within milliseconds, the local material of the metal cup rapidly absorbs heat and rises above the liquidus temperature. By precisely adjusting process parameters such as laser power and laser scanning speed, the melting depth and width can be controlled. After the laser beam is removed, the molten metal rapidly cools and solidifies in a vacuum environment, forming a strong welded joint. The laser vacuum welding method used in this invention can precisely control heat input and the welding area, making it suitable for complex structures. Simultaneously, the heat-affected zone is limited, preventing the diamond powder 10 inside the metal cup from being reheated and graphitized.

[0033] The present invention aims to prepare diamond composite sheets. After the production of the encapsulated metal cup is completed, the assembly process, sintering process and post-processing process need to be carried out in sequence.

[0034] In some specific embodiments of the present invention, the assembly process includes the following steps: Two encapsulated metal cups with an outer diameter ranging from 8.56 to 27.1 mm are fitted together inside a sodium chloride salt tube with an inner diameter of 8.7 to 27.3 mm, with a 1.0 to 2.5 mm thick sodium chloride salt sheet separating the two metal cups. A high-purity graphite tube with an inner diameter of 30.8 to 31.2 mm is then fitted over the salt tube. A 1.5 to 2.5 mm thick molybdenum sheet and a 5.0 to 12.0 mm thick conductive steel ring are sequentially fitted to both ends of the graphite tube. The entire assembly is then inserted into the central hole of a pyrophyllite cubic block with a side length of 44 to 46 mm to form a composite block.

[0035] In some specific embodiments of the present invention, the sintering process includes the following steps: placing the synthesized block in a six-sided press, raising the pressure to 6.0~10.0 GPa, and then heating the graphite tube with electricity, raising the temperature to a preset target range of 1500~1700℃ within 1~5 minutes. Maintaining this target pressure and temperature at a constant temperature and pressure for 6~10 minutes. Subsequently, the power is cut off and the tube is cooled under pressure to below 500℃, and finally, the pressure is slowly released to atmospheric pressure within 5~15 minutes.

[0036] In some specific embodiments of the present invention, the post-processing steps are as follows: The outer layer of pyrophyllite and auxiliary materials are peeled off and removed. The metal cup wall thickness is reduced to 0.05~0.15mm using machining, followed by thorough removal of residual encapsulating metal through chemical etching or sandblasting. The obtained diamond composite blank is then surface-ground and chamfered to a thickness of 0.1~0.6mm. Finally, after passing visual inspection and ultrasonic non-destructive testing, the finished diamond composite sheet is obtained.

[0037] The cemented carbide substrate 11 used in Examples 1-2 and Comparative Examples 1-2 of this invention is the same material with the same composition.

[0038] Example 1 Single-layer diamond powder 10 is selected, and its formula is obtained by ball milling 5wt% of 1~2μm, 80wt% of 20~30μm and 15wt% of 40~50μm diamond. The inner cup component 12 and the outer cup component 13 are made of the same molybdenum metal.

[0039] A method for preparing a diamond composite sheet, comprising the steps of vacuum sealing a metal cup and preparing the diamond composite sheet: The vacuum sealing process for metal cups includes the following steps: Step S201. Fill the inner cup component 12 with a 25mm inner diameter and a 0.3mm wall thickness with a cemented carbide matrix 11 and a diamond powder 10 in sequence. Then, fit the upper end with an outer cup component 13 with a 25.68mm inner diameter and a 0.3mm wall thickness to obtain the assembled metal cup, and then turn it upside down.

[0040] Step S202. Multiple assembled metal cups are simultaneously placed into a heat treatment furnace. A vacuuming process is first performed, achieving a vacuum level of 1×10⁻⁶ in the working chamber. -4 When Pa, restart the heating program, raise the temperature to 1000℃, and then keep it at that temperature for 120 minutes.

[0041] Step S203. Multiple vacuum heat-treated metal cups are simultaneously placed into the laser welding equipment. A vacuuming process is first performed, achieving a vacuum level of 1×10⁻⁶ in the working chamber. -3 At Pa, preheating is then performed. The preheating laser is a laser beam with a wavelength of 1064nm, the preheating power is set to 100W, the spot diameter is set to 2.0mm, the laser scanning speed is 10mm / s, the defocusing amount is +1.2mm, the preheating temperature is 500℃, and the preheating time is 30min.

[0042] Step S204. Using a laser beam with a wavelength of 1064nm and a laser power of 400W; the laser scanning speed is set to 100mm / s; the spot diameter is 0.3mm. The laser beam is rotated and welded 360° along the splicing area of ​​each metal cup in sequence to achieve the encapsulation of the metal cup in a vacuum environment, thus obtaining the encapsulated metal cup.

[0043] The preparation steps of diamond composite sheets include the following steps: Step S205. Assembly process: Select two encapsulated metal cups with an outer diameter of 26.28 mm and place them inside a sodium chloride salt tube with an inner diameter of 27 mm.

[0044] A high-purity graphite tube with an inner diameter of 31mm is fitted outside the salt tube.

[0045] An 8.0mm thick conductive steel ring and a 2mm thick metal molybdenum sheet are fitted at both ends of the graphite tube.

[0046] The entire component is inserted into the center hole of a 45mm pyrophyllite cube.

[0047] Step S206. Sintering process: The composite block is placed in a six-sided press, pressurized to 6 GPa, and then heated by electricity.

[0048] The temperature will rise to the preset parameter of 1500℃ within 2 minutes.

[0049] Maintain constant temperature and pressure for 8 minutes at the target pressure and temperature.

[0050] After power is cut off and the temperature is cooled to below 500°C, the pressure is slowly released over 15 minutes.

[0051] Step S207. Post-processing steps: The metal cup is removed by turning to a wall thickness of 0.1 mm, and then the metal cup is completely removed by sandblasting.

[0052] The obtained diamond composite blank is then subjected to surface finishing and chamfering.

[0053] The finished diamond composite sheet A was obtained after visual inspection and non-destructive testing.

[0054] Comparative Example 1 Preparation of conventional diamond composite sheets: The preparation method for conventional diamond composite sheets is the same as that for diamond composite sheets in Example 1, except that the metal cup is not subjected to the vacuum sealing steps S201-S204 and is used directly for the preparation of conventional diamond composite sheets.

[0055] The performance comparison results of diamond composite sheet A prepared according to the above method with conventional diamond composite sheet are shown in Table 1: Table 1

[0056] Table 1 above shows that when a metal cup encapsulated by a laser beam vacuum encapsulation process is used to prepare a diamond composite sheet, the resulting diamond composite sheet exhibits 19.3% higher wear resistance and 31.3% higher impact toughness compared to a conventional composite sheet.

[0057] Comparative Example 2 The metal cup is encapsulated using vacuum brazing, including the following steps: A double-layer diamond powder 10 is selected, wherein the working layer is formulated with 4wt% 1-2μm, 50wt% 10-15μm, 40wt% 20-30μm, and 6wt% 30-40μm diamonds obtained by ball milling, and the transition layer is formulated with 6wt% 1-2μm, 80wt% 20-30μm, and 14wt% 40-50μm diamonds obtained by ball milling. The inner cup component 12 is made of niobium metal, and the outer cup component 13 is made of zirconium metal. When loading the metal cup, the filling height of the working layer diamond powder and the transition layer diamond powder is the same.

[0058] (a) A cemented carbide matrix 11 and a double layer of diamond powder 10 are sequentially filled into an inner cup component 12 with an inner diameter of 15 mm and a wall thickness of 0.5 mm, and a 1.0 mm thick niobium-titanium alloy disc-shaped partition is placed on the top.

[0059] (b) A 2.0 mm thick sealing ring-shaped flow barrier is placed above the partition, the composition of which is alumina with a particle size ≤20 mesh.

[0060] (c) Fold the inner cup component sidewall inward to wrap the annular flow barrier, evenly lay Cu-Ag-Sn-Zn quaternary alloy solder on the upper part of the folded edge, and insert the outer cup component 13 with an inner diameter of 16.1 mm and a wall thickness of 0.5 mm into the upper end to obtain the assembled metal cup.

[0061] (d) Multiple assembled metal cups are simultaneously placed into a heat treatment furnace. A vacuuming process is first performed, achieving a vacuum level of 1×10⁻⁶ in the working chamber. -5 Pa, then restart the heating program, raise the temperature to 1200℃, and hold for 110 minutes. The heating causes the solder to completely melt, and under capillary action, fill the gap between the folded edge and the outer cup component 13 to form an airtight metallurgical joint.

[0062] The preparation method of the diamond composite sheet in Comparative Example 2 is the same as that in Example 1, except that the encapsulation method of the metal cup is different. The metal cup is encapsulated by vacuum brazing.

[0063] Example 2 A double-layer diamond powder 10 is selected. The working layer is formulated with 4 wt% of 1-2 μm, 50 wt% of 10-15 μm, 40 wt% of 20-30 μm, and 6 wt% of 30-40 μm diamonds obtained by ball milling. The transition layer is formulated with 6 wt% of 1-2 μm, 80 wt% of 20-30 μm, and 14 wt% of 40-50 μm diamonds obtained by ball milling. The inner cup component 12 is made of niobium metal, and the outer cup component 13 is made of zirconium metal. When loading the metal cup, the filling height of the working layer diamond powder and the transition layer diamond powder is the same.

[0064] A method for preparing a diamond composite sheet, comprising the steps of vacuum sealing a metal cup and preparing the diamond composite sheet: The vacuum sealing process for metal cups includes the following steps: Step S201. Fill the inner cup component 12 with a 15mm inner diameter and a 0.5mm wall thickness with a cemented carbide matrix 11 and a double layer of diamond powder 10 in sequence. Then, fit the upper end with an outer cup component 13 with a 16.1mm inner diameter and a 0.5mm wall thickness to obtain the assembled metal cup, and then turn it upside down.

[0065] Step S202. Multiple assembled metal cups are simultaneously placed into a heat treatment furnace. A vacuuming process is first performed, achieving a vacuum level of 1×10⁻⁶ in the working chamber. -5 When Pa, restart the heating program, raise the temperature to 1200℃, and then hold for 110 minutes.

[0066] Step S203. Multiple vacuum heat-treated metal cups are simultaneously placed into the laser welding equipment. A vacuuming process is first performed, achieving a vacuum level of 1×10⁻⁶ in the working chamber. -4 At Pa, preheating is then performed. The preheating laser is a laser beam with a wavelength of 1064nm, the preheating power is set to 120W, the spot diameter is set to 2.0mm, the laser scanning speed is 10mm / s, the defocusing amount is +1.2mm, the preheating temperature is 500℃, and the preheating time is 30min.

[0067] Step S204. Using a laser beam with a wavelength of 1064nm and a laser power of 600W; a laser scanning speed of 110mm / s; and a spot diameter of 0.2mm, the laser beam is rotated and welded 360° along the splicing area of ​​each metal cup in sequence to achieve the encapsulation of the metal cup in a vacuum environment, thus obtaining the encapsulated metal cup.

[0068] The diamond composite sheet B of Example 2 was prepared according to the preparation steps of the diamond composite sheet in Example 1. Its performance was statistically compared with that of a conventional diamond composite sheet and the diamond composite sheet of Comparative Example 2. The comparison results are shown in Table 2. Table 2

[0069] Metal cups were encapsulated using the encapsulation steps of Example 1 and Comparative Example 2, respectively. Example 1 used 5 batches, with 10 encapsulated metal cups per batch. Comparative Example 2 used the same setup, with a total of 100 samples. The encapsulation results were statistically analyzed. The comparison of the encapsulation success rates of the two encapsulation steps is shown in Table 3.

[0070] The packaging success rate is the percentage of successfully packaged metal cups out of the total number of packages. Water immersion ultrasonic C-scanning is used for non-destructive testing and assessment of weld quality. Determination of non-conformity: If a bright spot is observed within the depth range of the weld, it indicates the presence of defects such as gaps or bubbles, and the encapsulation is deemed non-conforming.

[0071] Acceptance criteria: If the image contrast is uniform throughout the entire weld depth range, the packaging is considered acceptable.

[0072] Table 3

[0073] Table 2 above shows that the metal cup encapsulated by the laser beam vacuum encapsulation step, when used to prepare diamond composite sheets, resulted in diamond composite sheets with 24.1% improved wear resistance and 50% improved impact toughness compared to conventional composite sheets. Compared to the diamond composite sheet in Comparative Example 2, the wear resistance was improved by 16.9% and the impact toughness by 26.3%. Table 3 above shows that the success rate of encapsulation using the laser beam vacuum encapsulation step in Example 1 was 30% higher than that of encapsulation using the brazing method in Comparative Example 2.

[0074] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0075] It should be noted that in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0076] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features of the invention herein.

Claims

1. A method for preparing a diamond composite sheet, characterized in that, The preparation method includes a vacuum sealing step for the metal cup, the vacuum sealing step comprising: The cemented carbide matrix and diamond powder are encapsulated in a metal cup formed by fitting an inner cup component and an outer cup component together, and the metal cup is then flipped over and placed. The metal cup is heated to remove impurities in a vacuum environment; In a vacuum environment, the splicing area of ​​the metal cup is preheated using a first laser beam; In a vacuum environment, a second laser beam is used to weld the preheated splicing area to obtain a packaged metal cup.

2. The method for preparing the diamond composite sheet according to claim 1, characterized in that, The inner cup component and the outer cup component both have a wall thickness of 0.12~0.5mm, the inner diameter of the inner cup component is 8~25mm, and the inner diameter of the outer cup component is 8.32~26.1mm.

3. The method for preparing the diamond composite sheet according to claim 1, characterized in that, The diamond powder has a particle size of 0.5~50μm.

4. The method for preparing the diamond composite sheet according to claim 1, characterized in that, The heating temperature is 700~1200℃, and the vacuum environment pressure is 1×10⁻⁶. -3 ~1×10 -5 Pa.

5. The method for preparing the diamond composite sheet according to claim 1, characterized in that, The first laser beam has a power of 50~150W, a spot diameter of 1.5~2.0mm, a laser scanning speed of 10~15mm / s, and a vacuum environment pressure of 1×10⁻⁶. -3 ~1×10 -5 Pa.

6. The method for preparing diamond composite sheets according to claim 1, characterized in that, The power of the second laser beam is 200~600W, the spot diameter is 0.1~0.3mm, and the laser scanning speed is 60~120mm / s.

7. The method for preparing a diamond composite sheet according to claim 1, characterized in that, The inner cup component and the outer cup component are independently selected from one or more materials selected from zirconium, niobium, molybdenum, and tantalum.

8. The method for preparing a diamond composite sheet according to claim 1, characterized in that, Preheating time is 5 to 30 minutes.

9. A diamond composite sheet, prepared by the method for preparing a diamond composite sheet according to any one of claims 1-8.

10. The application of the diamond composite sheet according to claim 9 in the fields of oil drilling and cutting tools.

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