A polycrystalline diamond compact and a method of making the same

Abstract

The present application relates to the technical field of superhard material manufacturing, and particularly relates to a polycrystalline diamond compact and a preparation method thereof. The preparation method of the polycrystalline diamond compact comprises the following steps: loading diamond micropowder, binder micropowder and polymer solution mixed to obtain diamond mixture and a hard alloy substrate into a metal cup to obtain a metal cup assembly; and sequentially performing vacuum heat treatment and sintering treatment on the metal cup assembly to obtain the polycrystalline diamond compact. The polymer solution is used to fill the gaps between the diamond micropowder, increase the content of carbon elements in the gaps, and play a lubricating and easy-to-load powder role. After the solvent is removed by vacuum heat treatment, the diamond micropowder is tightly packed due to capillary action, thereby promoting the sintering process and the density of the sintered body. The method promotes the dissolution-regrowth process of C at the gap position in the liquid binder, increases the density and D-D bond, improves the wear resistance of the PDC, and improves the heat resistance of the PDC.

Description

Technical Field

[0001] This invention relates to the field of superhard material manufacturing technology, and in particular to a polycrystalline diamond composite sheet and its preparation method. Background Technology

[0002] Polycrystalline diamond compact (PDC) is a common material in the superhard materials industry. It is typically produced by sintering diamond micropowder and a cemented carbide matrix under high temperature and pressure (HPHT) in the presence of a binder (such as iron, cobalt, or nickel). This type of material combines the high hardness and wear resistance of polycrystalline diamond with the toughness and impact resistance of cemented carbide, making it widely used in industries such as cutting tools, geological drilling, and oil extraction.

[0003] In actual production, even under high pressure, diamond, despite its high strength and resistance to deformation, still exhibits voids between its particles. During sintering, at high temperatures, the binder within the cemented carbide matrix melts and fills the gaps between diamond particles through melt infiltration, catalyzing the formation of DD bonds between the diamond particles, thus forming polycrystalline diamond that connects to the cemented carbide matrix. Due to the significant differences in the thermal expansion coefficients of diamond, binder, and cemented carbide matrix, the polycrystalline diamond layer is prone to cracking during use, even peeling off at the interface with the cemented carbide matrix, leading to operational failure and impacting drilling efficiency and drill bit lifespan. Further improvements are needed in heat resistance and other aspects.

[0004] Currently, some technologies exist to introduce nano-carbon sources, such as graphene, onion carbon, and carbon nanotubes, into the diamond layer, or to perform surface treatment on the diamond particles, in order to achieve better sintering results and improve the overall strength of PDC. However, these methods are easily limited by the powder mixing method, making it difficult to guarantee powder uniformity. If ball milling is used for mixing, new impurities may be introduced during the ball milling process due to the hardness of diamond. This uneven composition can easily form steric hindrance between diamond particles, reducing the density of the diamond layer and affecting the formation of DD bonds.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a polycrystalline diamond composite sheet and its preparation method, which aims to solve the problem that the density of the diamond layer decreases when a carbon source is introduced into the diamond layer.

[0007] The technical solution of the present invention is as follows:

[0008] A method for preparing a polycrystalline diamond composite sheet includes the following steps:

[0009] The polymer is mixed with a solvent to obtain a polymer solution;

[0010] Diamond micro powder, binder micro powder and the polymer solution are mixed to obtain a diamond mixture;

[0011] The diamond mixture and the cemented carbide matrix are loaded into a metal cup to obtain a metal cup assembly.

[0012] The metal cup assembly was subjected to vacuum heat treatment and sintering treatment in sequence to obtain a polycrystalline diamond composite sheet.

[0013] The method for preparing the polycrystalline diamond composite sheet, wherein the polymer is composed of at least two elements selected from C, H, O, N, Si, P and B.

[0014] The method for preparing the polycrystalline diamond composite sheet, wherein the solvent is selected from, but not limited to, one or more of water, ethanol, toluene, acetone, and hexane.

[0015] The method for preparing the polycrystalline diamond composite sheet, wherein the polymer solution has a mass fraction of 10%-60%.

[0016] The method for preparing the polycrystalline diamond composite sheet, wherein the average particle size of the diamond micropowder is 5μm-30μm.

[0017] The method for preparing the polycrystalline diamond composite sheet, wherein, in the diamond mixture, by mass percentage, the diamond micro powder accounts for 75wt%-99wt%, the binder micro powder accounts for 0-20wt%, and the polymer solution accounts for 1wt%-20wt%.

[0018] The method for preparing the polycrystalline diamond composite sheet, wherein the temperature of the vacuum heat treatment is 300℃-900℃ and the time of the vacuum heat treatment is 1h-10h.

[0019] The method for preparing the polycrystalline diamond composite sheet, wherein the sintering pressure is 5GPa-10GPa, the sintering temperature is 1300℃-1800℃, and the sintering time is 5min-60min.

[0020] A polycrystalline diamond composite sheet is prepared using a polycrystalline diamond composite sheet preparation method.

[0021] Beneficial Effects: This invention provides a polycrystalline diamond composite sheet and its preparation method. The preparation method includes the following steps: mixing a polymer with a solvent to obtain a polymer solution; mixing diamond micropowder, binder micropowder, and the polymer solution to obtain a diamond mixture; loading the diamond mixture and a cemented carbide matrix into a metal cup to obtain a metal cup assembly; and sequentially subjecting the metal cup assembly to vacuum heat treatment and sintering to obtain the polycrystalline diamond composite sheet. This invention utilizes the polymer solution to fill the gaps between diamond micropowder particles, increasing the carbon content in the gaps and simultaneously acting as a lubricant for easy powder loading. After removing the solvent through vacuum heat treatment, capillary action causes the diamond micropowder to pack tightly, thereby promoting the sintering process and the density of the sintered body. This method increases the carbon content of the entire polycrystalline diamond layer without reducing the tight packing of the original diamond powder, promotes the dissolution-regeneration process of C in the liquid binder at the interstitial sites, increases density and DD bonds, and improves the wear resistance of PDC. At the same time, some interstitial sites are used for the regeneration of C, reducing the binder content in the interstitial sites of PDC after sintering, thereby reducing the difference in the coefficient of thermal expansion of the polycrystalline diamond layer and improving the heat resistance of PDC. Attached Figure Description

[0022] Figure 1 This is a schematic flowchart of a method for preparing a polycrystalline diamond composite sheet according to the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of a polycrystalline diamond composite sheet according to the present invention;

[0024] Figure 3 This is a schematic diagram of the diamond mixture in Example 2;

[0025] Figure 4 This is a schematic diagram of the structure of the diamond mixture after heat treatment in Example 2;

[0026] Figure 5 This is a schematic diagram of the polycrystalline diamond layer after sintering in Example 2;

[0027] Explanation of reference numerals in the attached figures: Polycrystalline diamond layer 10, diamond micro powder 101, binder micro powder 102, polymer solution 103, polymer 104, DD bond 105, polycrystalline diamond 106, cemented carbide matrix 20. Detailed Implementation

[0028] This invention provides a polycrystalline diamond composite sheet and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0029] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0030] like Figure 1 The present invention provides a method for preparing polycrystalline diamond composite sheets, comprising the following steps:

[0031] Step S10: Mix the polymer with a solvent to obtain a polymer solution;

[0032] Step S20: Mix diamond micro powder, binder micro powder and the polymer solution to obtain diamond mixture;

[0033] Step S30: The diamond mixture and cemented carbide matrix are loaded into a metal cup to obtain a metal cup assembly;

[0034] Step S40: The metal cup assembly is subjected to vacuum heat treatment and sintering treatment in sequence to obtain a polycrystalline diamond composite sheet.

[0035] In this embodiment, a polymer is introduced into the gaps between diamond micropowders to fill the gaps, increasing the carbon content in the gaps and simultaneously acting as a lubricant for easy powder loading. After vacuum heat treatment to remove the solvent, capillary action causes the diamond micropowders to pack tightly, thereby promoting the sintering process and the density of the sintered body. This method increases the carbon content of the entire polycrystalline diamond layer without reducing the original tight packing of diamond micropowder, promoting the dissolution-regeneration process of C in the liquid binder at the gap locations, increasing density and DD bonds, and improving the wear resistance of PDC. At the same time, some gaps are used for the regrowth of C, reducing the binder content in the gaps of the PDC after sintering, thereby reducing the difference in the coefficient of thermal expansion of the polycrystalline diamond layer and improving the heat resistance of PDC.

[0036] Specifically, the polycrystalline diamond composite sheet prepared by this method does not form steric hindrance between diamond particles, which can increase the formation of DD bonds, making the polycrystalline diamond layer more compact. The polycrystalline diamond composite sheet prepared after high temperature and high pressure synthesis has excellent heat resistance and wear resistance. At the same time, additional properties can be imparted to the diamond layer by other elements on the polymer, thereby improving the overall strength.

[0037] In some embodiments, the polymer is composed of at least two elements selected from C, H, O, N, Si, P, and B. Introducing this polymer into the gaps between diamond micropowder particles to fill these gaps can increase the carbon content within the gaps. Furthermore, this type of polymer can act as a lubricant, facilitating powder loading and preventing powder spraying due to pressure changes during assembly or vacuuming. Simultaneously, other elements on the polymer can impart additional properties to the diamond layer, enhancing its overall strength.

[0038] In some embodiments, the polymer includes, but is not limited to, one or more of polyethylene glycol, polyether, polyester, polyethylene, polyacrylamide, and polycarbosilane. Introducing such polymers between diamond microparticles can increase the carbon content of the entire polycrystalline diamond layer without reducing the tight packing of the original diamond microparticles, promote the dissolution-regeneration process of carbon in interstitial positions in the liquid binder, increase density and DD bonds, and improve the wear resistance of PDC.

[0039] In some embodiments, the solvent is selected from, but not limited to, one or more of water, ethanol, toluene, acetone, and hexane. These solvents can effectively dissolve the polymer and can be removed by evaporation during vacuum heat treatment, thus facilitating the denser packing of diamond micropowder under capillary action.

[0040] In some embodiments, the polymer solution has a mass fraction of 10%-60%. Controlling the mass fraction of the polymer solution within the above range can introduce the polymer into the gaps between diamond particles, increase the carbon content in the gaps, and thus promote the sintering process and the density of the sintered body.

[0041] In some embodiments, the average particle size of the diamond microparticles is 5 μm-30 μm. Controlling the average particle size of the diamond microparticles within this range allows sufficient gaps between the diamond microparticles to fill the polymer.

[0042] Specifically, the diamond micro powder may consist of a single particle size distribution or a multi-particle size component distribution.

[0043] In some embodiments, the diamond mixture comprises, by mass percentage, 75wt%-99wt% diamond micropowder, 0-20wt% binder micropowder, and 1wt%-20wt% polymer solution. By controlling the mass percentage within this range, the carbon content in the entire polycrystalline diamond layer can be increased without reducing the tight packing of the original diamond powder, promoting the dissolution-regeneration process of carbon in interstitial positions in the liquid binder, increasing density and DD bonds, and improving the wear resistance of PDC.

[0044] Specifically, the amount of binder powder added should not exceed 100% of the volume of the interstitial space of the diamond powder under close packing conditions, to avoid steric hindrance caused by excessive addition of binder powder affecting the sintering bonding effect. Furthermore, the proportion of binder powder in the diamond mixture can be 0, in which case the binder in the cemented carbide matrix melts into the diamond interstitial space, promoting the sintering of the diamond powder.

[0045] In some embodiments, the binder powder includes, but is not limited to, one or more of Fe, Co, Ni, Nb, Ti, Zr, and Mo. During sintering under high temperature and pressure, the binder powder melts into a liquid state, promoting the dissolution and regrowth of carbon in the interstitial sites within the liquid binder, increasing density and DD bonds, and improving the wear resistance of PDC. Simultaneously, it allows some interstitial spaces to be used for carbon regrowth, reducing the binder content in the interstitial spaces of the PDC after sintering, thereby reducing the difference in the thermal expansion coefficient of the polycrystalline diamond layer and improving the heat resistance of the PDC.

[0046] In some embodiments, the particle size of the binder powder is less than 5 μm, including but not limited to 100 nm, 200 nm, 500 nm, 1 μm, etc.

[0047] In some embodiments, the temperature of the vacuum heat treatment is 300℃-900℃, and the time of the vacuum heat treatment is 1h-10h. The vacuum heat treatment can remove the solvent from the diamond mixture, and the polymer is partially retained in the gaps between the diamond microparticles. The introduction of the polymer solution makes the metal cup assembly less prone to powder spraying due to pressure changes during vacuum heat treatment, and the diamond microparticles are tightly packed due to capillary action, making them more compact. At the same time, the binder microparticles are located in the gaps between the tightly packed diamond microparticles.

[0048] Specifically, the temperature of the vacuum heat treatment can be determined based on the boiling point of the polymer actually used.

[0049] In some embodiments, the sintering pressure is 5 GPa-10 GPa, the sintering temperature is 1300℃-1800℃, and the sintering time is 5 min-60 min. In the polycrystalline diamond composite sheet obtained after high-temperature and high-pressure sintering, the polymer in the interstitial spaces participates in the reaction, and the carbon in the polymer undergoes a dissolution-regeneration process in the liquid binder, forming DD bonds between diamond microparticles to form the polycrystalline diamond layer. Simultaneously, because some interstitial spaces are used for carbon regrowth, the binder content of PDC in the interstitial spaces is reduced after sintering. The polycrystalline diamond composite sheet prepared after high-temperature and high-pressure synthesis exhibits excellent heat resistance and wear resistance.

[0050] In some embodiments, the cemented carbide matrix can be selected from commonly used cemented carbide matrices, including but not limited to WC-Co matrix, WC-Ni matrix, WC-Fe matrix, etc.

[0051] In addition, the present invention also provides a polycrystalline diamond composite sheet, which is prepared using a polycrystalline diamond composite sheet preparation method.

[0052] In this embodiment, the preparation method can be used to prepare a dense diamond composite sheet with high wear resistance and high heat resistance, as shown in the schematic diagram below. Figure 2 As shown, it includes a polycrystalline diamond layer 10 and a cemented carbide substrate 20 disposed on one side of the polycrystalline diamond layer 10; the polycrystalline diamond composite sheet prepared by this method has wide applications in cutting tools, geological drilling and oil extraction.

[0053] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0054] Example 1

[0055] A polymer solution was prepared by fully dissolving polyethylene glycol (PEG2000) with a molecular weight of 2000 in water, wherein the mass percentage of PEG2000 to water was 1:1. Diamond micropowder with a particle size of 10 μm was taken, and the polymer solution and diamond micropowder were thoroughly mixed in a mortar to prepare a diamond mixture. The mass percentage of diamond micropowder to polymer solution was 95:5. The diamond mixture from this example was placed on a cobalt-containing cemented carbide substrate, placed in a metal cup to form a metal cup assembly, and then placed in a vacuum furnace for vacuum heat treatment at 500℃ for 4 hours. The treated metal cup assembly was then subjected to high-temperature and high-pressure sintering at a sintering temperature of 1500℃ and a sintering pressure of 5.5 GPa for 10 minutes. After processing, the resulting blank was used to obtain a polycrystalline diamond composite sheet.

[0056] Due to the introduction of PEG, a small amount of polymer will remain in the gaps between diamond particles. The free carbon elements will dissolve in the liquid cobalt that permeates from the cemented carbide, increasing the carbon concentration in the gaps between diamond particles. Under the catalytic action of the binder that melts into the diamond layer from the cemented carbide matrix, the carbon will regrow on the surface of the diamond particles, promoting the formation of DD bonds at the gap sites.

[0057] Example 2

[0058] Polyether F127 (PEO) 106 -PPO 70 -PEO106 A polymer solution was prepared by fully dissolving polyether F127 in ethanol, wherein the mass percentage of polyether F127 to ethanol was 1:9. 20 μm diamond powder and 1 μm cobalt powder were taken and thoroughly mixed in a mortar to obtain a diamond mixture. The mass percentage of diamond powder, binder powder, and polymer solution was 85:5:10. A schematic diagram of the structure of this diamond mixture is shown below. Figure 3 As shown, it includes diamond micro powder 101, binder micro powder 102 located in the gaps between the diamond micro powder 101, and polymer solution 103 immersing the diamond micro powder 101 and the binder micro powder 102.

[0059] In this embodiment, the diamond mixture is placed on a cemented carbide substrate, inserted into a metal cup to form a metal cup assembly, and then placed in a vacuum furnace for vacuum heat treatment at 600°C for 6 hours. The structural diagram of the diamond mixture after heat treatment is shown below. Figure 4 As shown, the solvent in the polymer solution 103 has evaporated, and part of the polymer 104 remains in the interstitial positions of the diamond micropowder.

[0060] The treated metal cup assembly was subjected to high-temperature and high-pressure sintering at 1600℃ and 7GPa for 20 minutes. The resulting blank was then processed to obtain a polycrystalline diamond composite sheet. A schematic diagram of the sintered polycrystalline diamond layer is shown below. Figure 5 As shown, the polymer in the interstitial position participates in the reaction, and the carbon in the polymer undergoes a dissolution-regeneration process in the liquid binder, forming DD bonds 105 between diamond microparticles to form polycrystalline diamond 106. At the same time, since some of the interstitial space is used for the regeneration of carbon, the content of binder microparticles 102 in the interstitial space of PDC after sintering is reduced.

[0061] Due to the introduction of polyether F127, a small amount of polymer will still remain in the gaps between diamond particles. The free carbon elements will dissolve in the molten cobalt in the diamond gaps and the liquid binder that permeates from the cemented carbide, increasing the carbon concentration in the diamond particle gaps. Under the catalytic action of the binder in the diamond gaps, the carbon will regrow on the surface of the diamond particles, promoting the formation of DD bonds at the gap sites.

[0062] As demonstrated in Examples 1 and 2, diamond powder with a higher carbon concentration in the interstitial spaces of the above examples is clearly more conducive to the dissolution-regeneration process of the device, resulting in a higher sintering driving force and ultimately leading to a higher degree of diamond-diamond bonding, forming a PDC with higher density. Simultaneously, since some of the interstitial spaces are used for carbon regrowth, the binder content in the interstitial spaces of the PDC after sintering is reduced. Excess binder will migrate back into the cemented carbide matrix, thereby reducing the difference in the thermal expansion coefficient of the polycrystalline diamond layers and improving the heat resistance of the PDC.

[0063] In summary, this invention provides a polycrystalline diamond composite sheet and its preparation method. The preparation method includes the following steps: mixing a polymer with a solvent to obtain a polymer solution; mixing diamond micropowder, binder micropowder, and the polymer solution to obtain a diamond mixture; loading the diamond mixture and a cemented carbide matrix into a metal cup to obtain a metal cup assembly; and sequentially subjecting the metal cup assembly to vacuum heat treatment and sintering to obtain the polycrystalline diamond composite sheet. This invention utilizes the polymer solution to fill the gaps between diamond micropowder particles, increasing the carbon content in the gaps and simultaneously acting as a lubricant for easy powder loading. After removing the solvent through vacuum heat treatment, capillary action causes the diamond micropowder to pack tightly, thereby promoting the sintering process and the density of the sintered body. This method increases the carbon content of the entire polycrystalline diamond layer without reducing the tight packing of the original diamond powder, promotes the dissolution-regeneration process of C in the liquid binder at the interstitial sites, increases density and DD bonds, and improves the wear resistance of PDC. At the same time, some interstitial sites are used for the regeneration of C, reducing the binder content in the interstitial sites of PDC after sintering, thereby reducing the difference in the coefficient of thermal expansion of the polycrystalline diamond layer and improving the heat resistance of PDC.

[0064] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a polycrystalline diamond composite sheet, characterized in that, Including the following steps: The polymer is mixed with a solvent to obtain a polymer solution; Diamond micro powder, binder micro powder and the polymer solution are mixed to obtain a diamond mixture; The diamond mixture and the cemented carbide matrix are loaded into a metal cup to obtain a metal cup assembly. The metal cup assembly was subjected to vacuum heat treatment and sintering treatment in sequence to obtain a polycrystalline diamond composite sheet; The polymer comprises one or more of polyethylene glycol, polyether, polyester, polyethylene, polyacrylamide, and polycarbosilane; the solvent is selected from one or more of water, ethanol, toluene, acetone, and hexane; the polymer solution has a mass fraction of 10%-60%; the diamond micropowder is composed of a single particle size distribution or a multi-particle size distribution, and the average particle size of the diamond micropowder is 5μm-30μm; the binder micropowder comprises one or more of Fe, Co, Ni, Nb, Ti, Zr, and Mo; the particle size of the binder micropowder is below 5μm; The vacuum heat treatment temperature is 300℃-900℃, and the vacuum heat treatment time is 1h-10h; the sintering treatment pressure is 5GPa-10GPa, the sintering treatment temperature is 1300℃-1800℃, and the sintering treatment time is 5min-60min. In the diamond mixture, by mass percentage, the diamond micro powder accounts for 75wt%-99wt%, the binder micro powder accounts for 0-20wt%, and the polymer solution accounts for 1wt%-20wt%.

2. A polycrystalline diamond composite sheet, characterized in that, It is prepared using the method for preparing polycrystalline diamond composite sheets as described in claim 1.

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