An extremely thin diamond composite material and a preparation method thereof

Abstract

The present application relates to the field of diamond materials, and specifically discloses an ultra-thin diamond composite material and a preparation method thereof. An ultra-thin diamond composite material includes diamond powder, a composite binder and a cemented carbide matrix, wherein the composite binder includes 60-80% zirconium oxide and 20-40% polyimide, and the amount of the composite binder is 8-12% of the mass of the diamond powder; its preparation method is: mixing the diamond powder with the composite binder, placing the cemented carbide matrix into a mold, and then stacking the diamond powder containing the composite binder on one side of the cemented carbide matrix, with a stacking thickness of 2-3mm; using a pulse current to heat and sinter the mold, setting the pressure to 4-5GPa, and the sintering temperature to 700-900℃, to obtain an ultra-thin diamond composite material. The ultra-thin diamond composite material of the present application solves the problem of low processing efficiency and easy wear of existing ultra-thin polycrystalline diamond composite materials.

Description

Technical Field

[0001] The present application relates to the field of diamond materials, and more specifically, to an extremely thin diamond composite material and a preparation method thereof. Background Art

[0002] Polycrystalline diamond composite materials (also known as diamond composite sheets, English name: Polycrystalline Diamond, often abbreviated as PCD) are widely used in the production of superhard tools. Compared with tools made of traditional hard alloys, tool steels, ceramics and other materials, tools made of polycrystalline diamond composite materials have the advantages of high speed and efficiency, energy conservation and environmental protection, high machining accuracy, high machining surface finish, high wear resistance, long service life, high thermal conductivity, etc. Polycrystalline diamond composite materials are sintered and compounded by a polycrystalline diamond layer and a cemented carbide (WC-Co alloy) matrix at high temperature (about 1500 °C) and high pressure (about 6 GPa). For the finished diamond composite sheet used to make superhard tools, the thickness of its polycrystalline diamond layer generally does not exceed 1 mm, usually 0.3 mm - 0.8 mm.

[0003] With the application expansion of PCD tools in the machining field, and the widespread use of difficult-to-machine materials in the manufacturing industry (such as the automotive, aerospace, electronics, energy and other industries), especially for the high-speed, efficient and high-precision machining requirements of materials such as glass, ceramics, carbon fiber composite materials, superalloys, highly viscous metals, etc., the working surface thickness of the workpiece to be machined is relatively large. The general thin polycrystalline diamond layer PCD (the polycrystalline diamond working layer is usually about 0.5 mm, generally greater than 0.2 mm and less than 3 mm) is difficult to meet the machining requirements. During machining, it needs to be machined repeatedly, resulting in low machining efficiency. During the repeated machining process, there are also problems such as non-coincidence of the front and rear machining trajectories, unqualified machining accuracy, the need for subsequent finishing, and serious wear problems during the repeated machining process, which requires frequent tool replacement, affecting the machining efficiency and being not conducive to automatic batch operation on the production line. If the machining requirements are to be met, the working layer of the tool can be spliced by welding or other methods, which has the disadvantages of complex structure, high tool manufacturing cost, high brittleness, insufficient impact resistance, easy cracking and delamination at the splicing (welding) position, and low service life. Summary of the Invention

[0004] In order to solve the problem that the existing extremely thin polycrystalline diamond composite material needs to be machined repeatedly, resulting in low efficiency and easy wear, the present application provides an extremely thin diamond composite material and a preparation method thereof.

[0005] An extremely thin diamond composite material and a preparation method thereof provided by the present application adopt the following technical solutions:

[0006] An extremely thin diamond composite material and its preparation method, comprising diamond micropowder, a composite binder, and a cemented carbide substrate. The composite binder comprises 60 - 80% zirconia and 20 - 40% polyimide, and the dosage of the composite binder is 8 - 12% of the mass of the diamond micropowder.

[0007] By adopting the above technical solution, the diamond micropowder serves as the main hard component, providing high hardness and wear resistance. Zirconia and polyimide in the composite binder cooperate with each other. Zirconia provides hardness and stability, while polyimide provides flexibility and impact resistance. The combination of the two can effectively bond the diamond micropowder and improve the comprehensive properties of the material. The cemented carbide substrate provides a solid support for the entire composite material, bears the cutting force during the processing, and ensures the stability of the material during use. The dosage of the binder is between 8 - 12%, which helps to form a dense structure and improve the density of the material. This combination enables the material to have a good balance of hardness and toughness, effectively resisting wear and impact during the processing. When processing various materials, especially difficult-to-process materials, it can maintain the shape and performance of the tool, extend the tool life, and at the same time obtain high machining accuracy and surface quality.

[0008] Optionally, the preparation method of the composite binder is as follows:

[0009] Disperse zirconia powder with a particle size of 40 - 60 nm in an organic solvent, then add a surfactant and stir for reaction for 2 - 4 h;

[0010] Under nitrogen protection, add a mixed solution of diamine and dianhydride to the zirconia dispersion. The molar ratio of diamine to dianhydride is maintained at 1:1, control the reaction temperature at 150 - 200 °C, and the reaction time is 4 - 8 h;

[0011] After the reaction is completed, cool, wash, and dry the reaction product to obtain the composite binder.

[0012] By adopting the above technical solution, the surfactant reacts with the functional groups on the surface of zirconia to enhance its surface activity. Under nitrogen protection, diamine and dianhydride undergo a polycondensation reaction on the surface of zirconia to form polyimide and coat zirconia. Nitrogen protection is to prevent side reactions such as oxidation during the reaction process. The composite binder prepared by this method has zirconia uniformly coated with polyimide, enabling the binder to have both the high hardness of zirconia and the flexibility of polyimide, which can better bond the diamond micropowder, improve the bonding strength inside the material, and thus enhance the overall performance of the material.

[0013] Optionally, the particles with a particle size of 10 - 100 nm in the diamond micropowder account for 10 - 15% of the total mass of the diamond micropowder, and the particles with a particle size of 1 - 10 μm in the diamond micropowder account for 85 - 90% of the total mass of the diamond micropowder.

[0014] By adopting the above technical solution, the nanoscale diamond micropowder can fill the gaps between the micron-scale diamond micropowders, forming a denser microstructure. The nanodiamond micropowder has a high specific surface area and surface energy, which can enhance the bonding with the binder, and at the same time improve the hardness and wear resistance of the material. The micron-scale diamond micropowder provides the main supporting framework to ensure the overall strength of the composite material. This particle size distribution optimizes the packing mode of the diamond micropowder, makes the microstructure of the material more compact, and improves the hardness and wear resistance of the material. During the processing, it can cut the workpiece material more effectively, and can reduce the shedding of the diamond micropowder, prolonging the service life of the tool.

[0015] Optionally, it further includes yttrium micropowder with a particle size of 40-80 nm, and the addition amount of the yttrium micropowder is 0.2-0.4% of the mass of the diamond micropowder.

[0016] By adopting the above technical solution, during the sintering process, when the temperature of the material system rises and the diamond begins to crystallize and grow, there are certain differences in the surface energy and crystal structure between the rare earth element particles and the diamond. This difference makes it easier for diamond atoms to aggregate on the surface of the rare earth element particles and start to crystallize, thus increasing the number of nucleation sites. And the rare earth elements will hinder the diffusion and deposition of atoms to the grain surface, slowing down the grain growth rate. Under this dual effect, the diamond grains are refined, forming a more uniform and fine grain structure.

[0017] Optionally, the cemented carbide substrate is selected as a WC-TiC-Co cemented carbide substrate.

[0018] By adopting the above technical solution, by selecting a WC-TiC-Co cemented carbide substrate, WC serves as the hard phase to provide hardness, TiC further improves the hardness and wear resistance, and Co serves as the binder phase to ensure the toughness of the cemented carbide. The composition combination of this cemented carbide substrate makes it have high hardness, high wear resistance and good toughness, which can provide good support for the composite material, enhance the overall strength and stability of the tool, enable it to adapt to various complex processing environments, such as high-speed cutting, interrupted cutting, etc., and helps to improve the service life of the tool.

[0019] In a second aspect, the present application provides a method for preparing an ultra-thin diamond composite material, adopting the following technical solution:

[0020] A method for preparing an ultra-thin diamond composite material includes the following steps:

[0021] Mix the diamond micropowder with the composite binder, place the cemented carbide substrate in a mold, and then stack the diamond micropowder containing the composite binder on one side of the cemented carbide substrate, with a stacking thickness of 2-3 mm;

[0022] The mold is heated and sintered by pulsed current, with the pressure set at 4 - 5 GPa and the sintering temperature at 700 - 900 °C to obtain an extremely thin diamond composite material.

[0023] By adopting the above technical solution, compared with the traditional high-temperature and high-pressure sintering at 1500 °C, pulsed current sintering effectively avoids the graphitization transformation of diamond due to long-term heating at high temperatures and can refine the grains. During the pulsed current sintering process, since the heating time is extremely short, the diamond micropowder completes the sintering process before reaching the critical condition of graphitization. Inhibiting the graphitization of diamond ensures that the high hardness and high wear resistance characteristics of the diamond micropowder are fully retained. The fine grains increase the grain boundary area. The atomic arrangement at the grain boundaries is irregular, which can effectively hinder the movement of dislocations, thereby improving the strength and hardness of the material. On the other hand, the refined grains make the deformation of the material more uniform, reduce the stress concentration phenomenon, and improve the toughness and fatigue resistance of the material. This enables the extremely thin diamond composite material to better adapt and maintain good machining performance when facing complex machining conditions (such as interrupted cutting, high-speed cutting, etc.), making the material meet the requirements of high-speed, high-efficiency, and high-precision machining.

[0024] Optionally, yttrium micropowder needs to be added after the diamond micropowder is mixed with the composite binder.

[0025] Optionally, the sintered extremely thin diamond composite material is placed in a solution containing tungsten carbide and subjected to microwave heating treatment. The microwave frequency of the microwave heating treatment is 2.45 GHz, the power is 1300 - 1400 W, and the treatment time is 30 - 60 minutes.

[0026] By adopting the above technical solution, when the solution is microwave-heated, a strong convection phenomenon will occur. This convection enables the tungsten carbide particles in the solution to fully contact the surface of the extremely thin diamond composite material. In the high-temperature environment of microwave heating, the atomic activity on the surface of the composite material increases, which is conducive to the adsorption and diffusion of tungsten carbide particles on its surface. Within the treatment time of 30 - 60 minutes, tungsten carbide can form a certain diffusion layer on the surface and inside of the material, which will strengthen the performance of the material and further improve the hardness and wear resistance of the material.

[0027] Optionally, the surface of the sintered extremely thin diamond composite material is flushed with high-pressure water flow at 380 - 420 MPa and a jetting distance of 25 - 35 mm for 15 - 30 min.

[0028] By adopting the above technical solution, on the one hand, flushing with high-pressure water flow can improve the surface finish of the composite material and reduce surface impurities. On the other hand, the continuous shock wave generated by the high-pressure water flow can eliminate the residual stress on the surface of the composite material without damaging the material.

[0029] In summary, the present application has the following beneficial effects:

[0030] 1. Since the present application uses diamond micropowder in combination with zirconia and polyimide in the composite binder, the composite material achieves a good balance of hardness and toughness. It can not only effectively resist wear and impact during processing, but also maintain the tool shape and performance when processing various materials, especially difficult-to-process materials, extend the tool service life, and help obtain higher machining accuracy and surface quality.

[0031] 2. In the present application, yttrium micropowder is preferably used. Due to the differences in surface energy and crystal structure between rare earth element particles and diamond, diamond atoms are more likely to aggregate and crystallize on their surface, increasing the number of nucleation sites. At the same time, rare earth elements will hinder the diffusion and deposition of atoms to the grain surface to slow down the grain growth rate. Under the dual action, the diamond grains are refined, and finally a more uniform and fine grain structure is formed.

[0032] 3. In the method of the present application, compared with the traditional high-temperature and high-pressure sintering at 1500 °C, pulse current sintering effectively avoids the graphitization transformation of diamond due to long-term heating at high temperature, and can improve the strength and hardness of diamond, better adapt to and maintain good machining performance, so that the material can meet the requirements of high-speed, high-efficiency and high-precision machining. Specific Embodiments

[0033] The following further details the present application in conjunction with embodiments. It should be specifically noted that: for those not specifying specific conditions in the following embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. Except for special instructions, the raw materials used in the following embodiments can all be obtained from ordinary commercial sources.

[0034] Preparation Example 1

[0035] A preparation method of a composite binder:

[0036] Select nanoscale zirconia powder with a particle size range of 40 - 60 nm. The purity of the zirconia powder ≥ 99%. Select diamine and dianhydride as polyimide precursors. The diamine is 4,4-diaminodiphenyl ether (ODA), and the dianhydride is pyromellitic dianhydride (PMDA). The purity of the diamine and dianhydride ≥ 99.5%.

[0037] Disperse 7 kg of zirconia powder in 10 kg of organic solvent N-methylpyrrolidone, and use an ultrasonic disperser for dispersion. The ultrasonic power is 300 W, and the dispersion time is 30 minutes.

[0038] Add 30 g of silane coupling agent to the dispersed zirconia solution, stir and react. The stirring speed is 400 rpm, and the reaction time is 3 hours, thus completing the pretreatment.

[0039] Place the pre-treated zirconia solution in a reaction kettle. Under nitrogen protection, drop a mixed solution of diamine and dianhydride into it. The mixed solution contains 1.572 kg of diamine and 1.712 kg of dianhydride. The molar ratio of diamine to dianhydride is 1:1. Control the reaction temperature at 180 °C and the reaction time at 6 hours. Stir continuously during the reaction, and the stirring speed is 200 rpm.

[0040] After the reaction is completed, cool the reaction product to room temperature, and then perform centrifugal separation. The centrifugal speed is 4000 rpm and the time is 10 minutes.

[0041] Wash the centrifuged solid product with N-methylpyrrolidone. After washing, dry the product in a vacuum drying oven at a drying temperature of 80 °C for 12 hours. After drying, pulverize it to obtain a composite binder with polyimide coated on the surface of zirconia, where polyimide accounts for 30% of the total mass.

[0042] Preparation Example 2

[0043] A method for preparing a composite binder: The difference from Preparation Example 1 is that 8 kg of zirconia powder, 1.047 kg of diamine and 1.141 kg of dianhydride are used, and polyimide in the obtained composite binder accounts for 20% of the total mass.

[0044] Preparation Example 3

[0045] A method for preparing a composite binder: The difference from Preparation Example 1 is that 6 kg of zirconia powder, 2.095 kg of diamine and 2.282 kg of dianhydride are used, and polyimide in the obtained composite binder accounts for 40% of the total mass.

[0046] Preparation Example 4

[0047] A method for preparing a composite binder: The difference from Preparation Example 1 is that 9 kg of zirconia powder, 524.63 g of diamine and 571.47 g of dianhydride are used, and polyimide in the obtained composite binder accounts for 10% of the total mass.

[0048] Preparation Example 5

[0049] A method for preparing a composite binder: The difference from Preparation Example 1 is that 5 kg of zirconia powder, 2.619 kg of diamine and 2.853 kg of dianhydride are used, and polyimide in the obtained composite binder accounts for 50% of the total mass.

[0050] Example 1

[0051] A method for preparing an extremely thin diamond composite material:

[0052] Prepare diamond micropowder with a purity of ≥99%. The particles with a particle size of 10 - 100 nm in the diamond micropowder account for 13% of the total mass of the diamond micropowder, and the particles with a particle size of 1 - 10 μm account for 87% of the total mass of the diamond micropowder. Select WC-TiC-Co cemented carbide as the cemented carbide substrate. The WC content in the alloy is 91.5%, the Co content is 7.3%, and the TiC content is 1.2%. The diameter of the cemented carbide substrate is 12 mm and the thickness is 10 mm. The composite binder is prepared according to Preparation Example 1.

[0053] Put 100 g of diamond micropowder and 10 g of composite binder into a ball mill for mixing. Control the ball-to-material ratio at 2:1, the mixing time at 1 h, and the rotation speed at 200 rpm to obtain mixed powder.

[0054] Put the cemented carbide substrate into a mold, and then evenly stack the mixed powder on one side of the cemented carbide substrate. The stacking thickness is 2.5 mm. Adopt the method of layered stacking, with the thickness of each layer controlled at 0.5 mm. During the stacking process, use a vibrator to compact and level the powder.

[0055] Put the mold containing the stacked powder and the cemented carbide substrate into the furnace of the pulse current sintering equipment. Apply a pressure of 4.5 ± 0.1 GPa to the mold through a pressure device. In an argon environment, adjust the pulse current density to 250 - 350 A / cm² and the pulse frequency to 5 - 10 Hz through a pulse current control system, so that the sintering temperature is controlled at 800 ± 10 °C and the sintering time is 15 minutes. After sintering is completed, turn off the equipment. After the furnace cools to room temperature, take out the sintered product to obtain an ultra-thin diamond composite material.

[0056] Example 2

[0057] A method for preparing an ultra-thin diamond composite material: The difference from Example 1 is that 100 g of diamond micropowder and 8 g of composite binder are put into a ball mill for mixing.

[0058] Example 3

[0059] A method for preparing an ultra-thin diamond composite material: The difference from Example 1 is that 100 g of diamond micropowder and 12 g of composite binder are put into a ball mill for mixing.

[0060] Example 4

[0061] A method for preparing an ultra-thin diamond composite material: The difference from Example 1 is that the composite binder is prepared according to Preparation Example 2.

[0062] Example 5

[0063] A preparation method of an extremely thin diamond composite material: The difference from Example 1 is that the composite binder is prepared from Preparation Example 3.

[0064] Example 6

[0065] A preparation method of an extremely thin diamond composite material: The difference from Example 1 is that the particles with a particle size of 10 - 100 nm in the fine powder account for 10% of the total mass of the diamond fine powder, and the particles with a particle size of 1 - 10 μm account for 90% of the total mass of the diamond fine powder.

[0066] Example 7

[0067] A preparation method of an extremely thin diamond composite material: The difference from Example 1 is that the particles with a particle size of 10 - 100 nm in the fine powder account for 15% of the total mass of the diamond fine powder, and the particles with a particle size of 1 - 10 μm account for 85% of the total mass of the diamond fine powder.

[0068] Example 8

[0069] A preparation method of an extremely thin diamond composite material: The difference from Example 1 is that the cemented carbide matrix is a WC - Co cemented carbide matrix, and the WC content in the alloy is 92.5% and the Co content is 7.5%.

[0070] Example 9

[0071] A preparation method of an extremely thin diamond composite material: The difference from Example 1 is that 100 g of diamond fine powder, 8 g of composite binder, and 0.3 g of yttrium fine powder with a particle size of 40 - 80 nm are put into a ball mill for mixing.

[0072] Example 10

[0073] A preparation method of an extremely thin diamond composite material: The difference from Example 9 is that 100 g of diamond fine powder, 8 g of composite binder, and 0.2 g of yttrium fine powder with a particle size of 40 - 80 nm are put into a ball mill for mixing.

[0074] Example 11

[0075] A preparation method of an extremely thin diamond composite material: The difference from Example 9 is that 100 g of diamond fine powder, 8 g of composite binder, and 0.4 g of yttrium fine powder with a particle size of 40 - 80 nm are put into a ball mill for mixing.

[0076] Example 12

[0077] A preparation method of an extremely thin diamond composite material: The difference from Example 1 is that the temperature of pulse current sintering is controlled at 700 °C.

[0078] Example 13

[0079] Method for preparing ultra-thin diamond composite material: The difference from Example 1 is that the temperature control of pulse current sintering is at 900 °C.

[0080] Example 14

[0081] Method for preparing ultra-thin diamond composite material: The difference from Example 1 is that the ultra-thin diamond composite material is immersed in an acetone solution containing 25% tungsten carbide and subjected to microwave heating treatment. The microwave frequency of the microwave heating treatment is 2.45 GHz, the power is 1400 W, and the treatment time is 45 minutes. After the treatment is completed, the ultra-thin diamond composite material is removed, washed with water, and then dried.

[0082] Example 15

[0083] Method for preparing ultra-thin diamond composite material: The difference from Example 1 is that the surface of the prepared ultra-thin diamond composite material is washed with high-pressure water flow at 400 MPa and a spraying distance of 30 mm for 20 min.

[0084] Comparative Example 1

[0085] Method for preparing ultra-thin diamond composite material: The difference from Example 1 is that no composite binder is added.

[0086] Comparative Example 2

[0087] Method for preparing ultra-thin diamond composite material: The difference from Example 1 is that the composite binder is prepared from Preparation Example 4.

[0088] Comparative Example 3

[0089] Method for preparing ultra-thin diamond composite material: The difference from Example 1 is that the composite binder is prepared from Preparation Example 5.

[0090] 1. Abrasion resistance test method and conditions: The ultra-thin diamond composite materials prepared by the present invention are all processed into cylinders of the same size (diameter 10 mm, height 5 mm), fixed on the tool holder of a numerically controlled lathe, and used to turn a granite round bar. The turning parameters are: linear speed 50 - 200 m / min; cutting depth 0.1 - 0.5 mm; feed 0.1 - 0.5 mm / r. After cutting a mileage of 2000 m, the wear degree of the cutting edge is measured under an optical microscope, and the wear ratio is calculated. The wear ratio is the ratio of the volume of the machined material removed to the volume of the tool material worn.

[0091] 2. Impact toughness test method and conditions: The heavy weight impact method is used for testing. The single impact energy is 0.5J. During the test, the sample is placed on the steel plate of the impact frame, and an axial pressure of 1000N is applied to the sample through the steel rod. Then the hammer is dropped several times until the sample is completely destroyed. The number of drops when the sample is destroyed (total impact energy) is used as an indicator to measure the impact resistance of the composite sheet.

[0092] Table 1 Test data

[0093] Wear ratio Impact toughness / J Example 1 180,000 369 Example 2 170,000 362 Example 3 180,000 367 Example 4 180,000 365 Example 5 180,000 367 Example 6 170,000 361 Example 7 180,000 370 Example 8 180,000 360 Example 9 200,000 378 Example 10 190,000 375 Example 11 200,000 377 Example 12 180,000 370 Example 13 180,000 368 Example 14 190,000 376 Example 15 190,000 372 Comparative Example 1 140,000 320 Comparative Example 2 150,000 353 Comparative Example 3 150,000 365

[0094] Combining Example 1 and Comparative Example 1 with Table 1, it can be seen that in Example 1, a composite binder comprising zirconium oxide and polyimide is used to prepare an ultra-thin diamond composite material, and its wear ratio reaches 180,000 and its impact toughness is 369 J. In Comparative Example 1, no composite binder is added, and the wear ratio drops to 140,000 and the impact toughness also drops to 320 J. This shows that the composite binder can significantly improve the wear resistance and impact toughness of the material. The composite binder can effectively bond the diamond powder, making the material more wear-resistant during the cutting process and better able to maintain structural integrity when subjected to impact.

[0095] Combining Examples 1, 4, 5 and Comparative Examples 2-3 and Table 1, it can be seen that after the composite binder in Example 1 is prepared, the polyimide accounts for 30% of the total mass, the wear ratio is 180,000, and the impact toughness is 369J. In Example 4, the composite binder polyimide accounts for 20% of the total mass, and the performance is similar to that of Example 1; in Example 5, the composite binder polyimide accounts for 40% of the total mass, and the performance is also similar to that of Example 1. In Comparative Example 2, the composite binder polyimide accounts for 10% of the total mass, the wear ratio drops to 150,000, and the impact toughness is 353J; in Comparative Example 3, the composite binder polyimide accounts for 50% of the total mass, the wear ratio is 150,000, and the impact toughness is 365J. This shows that the content of polyimide in the composite binder has little effect on the material properties within the scope of this application. When the polyimide content is too high or too low, the wear resistance and impact toughness of the material will decrease.

[0096] It can be seen from Examples 1-3 and Table 1 that the amount of composite binder used has an impact on material properties. The amount added in this application helps to maintain good wear resistance and impact toughness, and an addition amount of 10% is the most preferred in this application.

[0097] Combined with Example 1, Example 6, and Example 7 and Table 1, it can be seen that the content of nanoscale particles in diamond micropowder has an impact on the material properties. Appropriately increasing the content of nanoscale particles can, to a certain extent, improve the impact toughness. In this application, the optimal situation is that the particles with a particle size of 10 - 100 nm in diamond micropowder account for 13% of the total mass of diamond micropowder, balancing performance and manufacturing cost. Continuing to increase the mass of nanoscale particles will not have too much impact on the properties of the composite material.

[0098] Combined with Example 1 and Example 8 and Table 1, it can be seen that in Example 1, a WC - TiC - Co cemented carbide matrix was selected, and the impact toughness was 369 J; in Example 8, a WC - Co cemented carbide matrix was selected, and the impact toughness was 360 J. This indicates that the change in the composition of the cemented carbide matrix has little effect on the wear resistance of the material, but has a certain impact on the impact toughness of the material. The WC - TiC - Co cemented carbide matrix performs better in terms of impact toughness than the WC - Co cemented carbide matrix.

[0099] Combined with Example 1, Example 9 - 11 and Table 1, it can be seen that in Example 1, no yttrium micropowder was added, the wear ratio was 180,000, and the impact toughness was 369 J; in Example 9, 0.3 g of yttrium micropowder was added, the wear ratio increased to 200,000, and the impact toughness was 378 J; in Example 10, 0.2 g of yttrium micropowder was added, the wear ratio was 190,000, and the impact toughness was 375 J; in Example 11, 0.4 g of yttrium micropowder was added, the wear ratio was 200,000, and the impact toughness was 377 J. It shows that adding yttrium micropowder can effectively improve the wear resistance and impact toughness of the material, and can achieve a good effect of strengthening the composite material within the scope of this application.

[0100] Combined with Example 1, Example 12, and Example 13 and Table 1, it can be seen that within the sintering temperature range of 700 - 900 °C, it has little effect on the wear resistance of the material, has a certain impact on the impact toughness, but the change range is not large, and the material can maintain relatively stable performance within this temperature range.

[0101] Combined with Example 1, Example 14, and Example 15 and Table 1, it can be seen that both the microwave heating treatment of tungsten carbide solution and the post - treatment process of high - pressure water flow flushing can, to a certain extent, improve the wear resistance and impact toughness of the material, which helps to improve the comprehensive performance of the material.

[0102] This specific embodiment is only an interpretation of this application, and it is not a limitation of this application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of this application, it is protected by the patent law.

Claims

1. An ultra-thin diamond composite material, characterized in that: It comprises diamond micropowder, a composite binder, a cemented carbide matrix and yttrium micropowder with a particle size of 40-80nm, wherein the composite binder comprises 60-80% of zirconium oxide and 20-40% of polyimide, the amount of the composite binder is 8-12% of the mass of the diamond micropowder, and the amount of the yttrium micropowder added is 0.2-0.4% of the mass of the diamond micropowder; The preparation method of the composite binder is: Disperse zirconium oxide powder with a particle size of 40-60 nm in an organic solvent, add a surfactant, and stir to react for 2-4 hours; Under nitrogen protection, a mixed solution of diamine and dianhydride is added to the zirconium oxide dispersion, the molar ratio of diamine to dianhydride is maintained at 1:1, the reaction temperature is controlled at 150-200°C, and the reaction time is 4-8 h; After the reaction is completed, the reaction product is cooled, washed and dried to obtain a composite adhesive.

2. The ultra-thin diamond composite material according to claim 1, characterized in that: In the diamond micropowder, particles with a particle size of 10-100 nm account for 10-15% of the total mass of the diamond micropowder, and particles with a particle size of 1-10 μm account for 85-90% of the total mass of the diamond micropowder.

3. The ultra-thin diamond composite material according to claim 1, characterized in that: The hard alloy substrate is a WC-TiC-Co hard alloy substrate.

4. A method for preparing an ultra-thin diamond composite material according to any one of claims 1 to 3, characterized in that: The following steps are involved: Mix the diamond powder with the composite binder, put the cemented carbide substrate into the mold, and then stack the diamond powder containing the composite binder on one side of the cemented carbide substrate with a stacking thickness of 2-3mm; Pulse current is used to heat and sinter the mold, the pressure is set to 4-5GPa, and the sintering temperature is set to 700-900℃ to obtain an extremely thin diamond composite material.

5. The method for preparing the ultra-thin diamond composite material according to claim 4, characterized in that: After the diamond micropowder is mixed with the composite binder, yttrium micropowder needs to be added.

6. The method for preparing the ultra-thin diamond composite material according to claim 4, characterized in that: The obtained ultra-thin diamond composite material is placed in a solution containing tungsten carbide and subjected to microwave heating treatment, wherein the microwave frequency of the microwave heating treatment is 2.45 GHz, the power is 1300-1400 W, and the treatment time is 30-60 minutes.

7. The method for preparing the ultra-thin diamond composite material according to claim 4, characterized in that: The surface of the obtained ultra-thin diamond composite material is washed with a high-pressure water flow of 380-420 MPa and a spray distance of 25-35 mm for 15-30 minutes.