A CVD diamond cutting tooth and a preparation method and application thereof

Abstract

The application provides a CVD diamond cutting tooth and a preparation method and application thereof, and the CVD diamond cutting tooth comprises a CVD diamond thick film, a welding transition layer and a hard alloy base. The preparation method of the diamond cutting tooth comprises the following steps: S1, preparing a diamond thick film, polishing and polishing to a mirror surface, and then cutting into a target shape through laser cutting; S2, mixing welding transition layer raw materials in proportion, and uniformly coating the growth surface of the CVD diamond thick film and the surface of the hard alloy base; S3, combining the growth surface of the CVD diamond thick film and the surface of the hard alloy base, then applying a pressure load from top to bottom on the nucleation surface of the CVD diamond thick film, and then placing in a vacuum furnace for welding treatment to obtain the CVD diamond cutting tooth. The application can realize effective connection of the CVD diamond film and the hard alloy base, and jointly form the CVD diamond cutting tooth.

Description

Technical Field

[0001] This invention belongs to the field of diamond cutting tooth technology, and specifically relates to a high-performance CVD diamond cutting tooth, its preparation method, and its application. Background Technology

[0002] Diamond drill bits are currently the most widely used type of drill bit in geological exploration and development. During operation, the cutting teeth embedded in the drill bit alternately contact the bottom of the well to achieve rock breaking and drilling footage. The mechanical properties of the cutting teeth directly determine the lifespan and working efficiency of the diamond drill bit. In 1971, General Electric Company of the United States developed the polycrystalline diamond composite drill bit (PDC drill bit), and it was first used in 1973, thus opening a new era of using diamond as the cutting teeth of drill bits. PDC drill bits are ultra-hard composite materials composed of a cemented carbide matrix and polycrystalline diamond. Its specific preparation method involves spreading diamond micro-powder on top of the cemented carbide matrix and synthesizing it under high temperature and high pressure conditions. PDC drill bits combine the wear resistance of diamond and the toughness of cemented carbide. However, as shallow geological resources are depleted, geological exploration is gradually advancing to more complex and abrasive deeper layers, at which point the temperature of the drilling face rises sharply. Under these conditions, PDC drill bits will suffer "thermal damage" due to the residual metal binder inside, and thus fail and become unusable. Developing diamond without metal binders and fabricating cutting teeth to avoid high-temperature thermal failure of PDC drill bits is of great significance.

[0003] Chemical vapor deposition (CVD) is the most promising process for the synthesis of synthetic diamonds. It contains 100% diamond elements, no metal binders, and does not exhibit thermal failure at high temperatures. If CVD diamond films of a certain thickness are prepared and combined with cemented carbide substrates to form cutting teeth, it will represent a significant revolution and upgrade to existing diamond cutting elements.

[0004] The main challenges in fabricating CVD diamond cutting teeth in existing technologies are twofold: First, the high interfacial energy between CVD diamond and metal makes diamond difficult to wet with common metals, resulting in extremely poor weldability. Second, during diamond deposition, the preferential growth of crystals along a certain direction leads to the gradual formation of V-shaped columnar crystals that are thinner at the bottom and thicker at the top. The presence of these columnar crystals results in high internal stress in the diamond film, leading to a decrease in mechanical properties such as impact resistance, toughness, and wear resistance. As the deposition time increases, the growth of columnar crystals becomes more pronounced, further degrading the quality and mechanical properties of the thick diamond film. Third, during the hot-filament CVD deposition process, carbon buildup inevitably occurs on the filament, and this buildup increases with deposition time. Severe carbon buildup on the filament can affect the quality of the diamond film and even interrupt the deposition process.

[0005] CN201810306685.0 discloses a method for depositing CVD diamond thick films on a molybdenum substrate. However, this method only achieves the target deposition thickness by extending the deposition time, resulting in a CVD diamond thick film containing a large number of columnar crystals, which severely affects its mechanical properties. CN201910711380.2 discloses a high-efficiency heat dissipation material made of diamond film and its preparation method. This method involves vacuum welding a self-supporting CVD diamond film to metallic copper using a special flux and welding process. However, this method is only suitable for heat dissipation materials, and the welding strength cannot meet the requirements of cutting teeth. Summary of the Invention

[0006] During the research, it was found that existing composite cutting teeth made of PCD diamond and cemented carbide substrate are integrally formed by diamond particles and cemented carbide substrate under high temperature and high pressure conditions. The cross-sectional bonding strength is high and there is no need to consider the interface compatibility problem. However, when cutting teeth are made by combining CVD thick film and cemented carbide substrate, it is necessary to prepare them by vacuum brazing CVD diamond thick film and cemented carbide substrate. The following difficulties exist in the brazing process: (1) CVD diamond has a very low coefficient of thermal expansion, while cemented carbide has a high coefficient of thermal expansion. During vacuum brazing, the different coefficients of thermal expansion of the two lead to large stress at the interface connection and poor bonding force; (2) A large amount of heat is generated during the use of CVD diamond cutting teeth. CVD diamond has a high thermal conductivity, but conventional brazing materials have a low thermal conductivity, which leads to heat accumulation at the interface, increasing the temperature and reducing the interface bonding strength, resulting in desoldering.

[0007] To address the aforementioned technical problems, this invention provides a CVD diamond cutting tooth, its preparation method, and its application. In the preparation method of this invention, by adjusting the flux and welding process, an effective connection between the CVD diamond film and the cemented carbide substrate is achieved, jointly forming the CVD diamond cutting tooth. The CVD diamond cutting teeth provided by this invention can be mass-produced into diamond drill bits for use in oil extraction and geological exploration.

[0008] The first aspect of the present invention provides a CVD diamond cutting tooth, the CVD diamond cutting tooth comprising a CVD diamond thick film, a welding transition layer and a cemented carbide substrate.

[0009] Furthermore, according to some specific embodiments of the present invention, the thickness of the CVD diamond thick film is greater than or equal to 0.5 mm, preferably greater than or equal to 1.0 mm, and more preferably 1.0 to 2.0 mm.

[0010] Furthermore, according to some specific embodiments of the present invention, the CVD diamond thick film is a micron-sized polycrystalline structure, and the crystal size of the micron-sized polycrystalline structure is 10 to 300 μm; the crystal morphology of the micron-sized polycrystalline structure is one or more of cubic, octahedral, truncated octahedral, and faceted morphology, preferably octahedral morphology; when it includes two or more crystal morphologies, it is a chaotic non-preferred orientation crystal composed of two or more crystal morphologies.

[0011] Furthermore, according to some specific embodiments of the present invention, the CVD diamond thick film crystals are tightly connected by DD bonds, and there are no obvious grain boundaries between the crystals.

[0012] Furthermore, according to some specific embodiments of the present invention, the I of the CVD diamond thick film... G / I D <0.2, preferably I G / I D <0.15; the carbon atoms are characterized by Raman spectroscopy, I G This indicates that SP 2 Characteristic peak intensity of hybrid graphite phase crystals, I D This represents the intensity of the characteristic peak of the SP3 hybrid diamond phase.

[0013] Furthermore, according to some specific embodiments of the present invention, the cross-sectional crystal size of the CVD diamond thick film is consistent from top to bottom, and there are no columnar crystals that are thinner at the bottom and thicker at the top. The consistent crystal size from top to bottom also proves that the columnar crystal problem that has appeared in CVD diamond during long-term deposition has been significantly improved.

[0014] Furthermore, according to some specific embodiments of the present invention, the CVD diamond thick film is matched in shape and size to the cemented carbide substrate, and is one or more of cylindrical, polygonal, or prismatic shapes, preferably cylindrical, and more preferably cylindrical with a diameter of 10-20 mm. The CVD diamond thick film is generally ground and polished to a mirror finish, and then laser-cut into the target shape.

[0015] Furthermore, according to some specific embodiments of the present invention, the welding transition layer is an intermediate layer connecting the CVD diamond thick film and the cemented carbide substrate. Its main function is to ensure effective connection and heat conduction between the CVD diamond thick film and the cemented carbide substrate, so that the CVD diamond thick film and the cemented carbide substrate do not separate and fail during the use of the cutting tooth assembly.

[0016] Furthermore, according to some specific embodiments of the present invention, the weld transition layer comprises diamond powder, tungsten carbide particles, and a binder; based on the total weight of the weld transition layer, the mass percentage of diamond powder is 10% to 30%, preferably 15% to 20%; the mass percentage of tungsten carbide particles is 5% to 25%, preferably 10% to 15%; and the mass percentage of the binder is 45% to 85%, preferably 65% ​​to 75%.

[0017] Furthermore, according to some specific embodiments of the present invention, the diamond powder has a particle size of 0.1 to 10 μm, and / or the tungsten carbide particles have a particle size of 1 to 10 μm.

[0018] Furthermore, according to some specific embodiments of the present invention, the binder is a metal binder, including silver, titanium, cobalt and copper, wherein, based on the total weight of the binder, the mass percentage of silver is 25% to 45%, the mass percentage of titanium is 15% to 35%, the mass percentage of cobalt is 30% to 40%, and the mass percentage of copper is 10% to 20%.

[0019] Furthermore, according to some specific embodiments of the present invention, the cemented carbide substrate may be selected from any one or more of the existing cemented carbides in the art, including but not limited to tungsten-cobalt cemented carbides, tungsten-titanium-cobalt cemented carbides, etc.

[0020] Furthermore, according to some specific embodiments of the present invention, the cemented carbide substrate is processed into a shape and size that matches the CVD diamond thick film.

[0021] A second aspect of the present invention provides a method for preparing diamond cutting teeth, the method comprising the following steps:

[0022] S1, prepare a diamond thick film, grind and polish it to a mirror finish, and then cut it into the target shape by laser cutting;

[0023] S2, the welding transition layer raw materials are mixed in proportion and uniformly coated on the growth surface of CVD diamond thick film and the surface of cemented carbide substrate;

[0024] S3, the growth surface of the CVD diamond thick film is combined with the surface of the cemented carbide substrate, and then a pressure load from top to bottom is applied to the nucleation surface of the CVD diamond thick film. Then, it is placed in a vacuum furnace for welding treatment to obtain CVD diamond cutting teeth.

[0025] Furthermore, according to some specific embodiments of the present invention, in the above-mentioned method for preparing diamond cutting teeth, the method for preparing the diamond thick film in step S1 includes the following steps:

[0026] (1) A CVD diamond film is obtained on a substrate using a first growth process;

[0027] (2) Then, the unmodified CVD diamond film obtained in step (1) is modified using the second processing technology;

[0028] (3) Then, a third transition process is used to perform a transition treatment on the modified CVD diamond film obtained in step (2);

[0029] (4) Repeat steps (1) to (3) for n cycles to obtain a CVD diamond thick film.

[0030] Furthermore, according to some specific embodiments of the present invention, the substrate in step (1) can be selected as needed, and can be at least one of molybdenum, silicon, tungsten, titanium, graphite, etc. The shape of the substrate can be any shape, and the size of the substrate is not limited.

[0031] Furthermore, according to some specific embodiments of the present invention, the first growth process in step (1) is as follows: the first gas phase flow, the second gas phase flow and the third gas phase flow are respectively introduced into the hot filament CVD diamond deposition furnace, the CVD diamond deposition furnace parameters are set as the first growth process parameters, and the first growth time is run.

[0032] Furthermore, according to some specific embodiments of the present invention, the first gas phase flow can be one or more of a carbon-containing gaseous organic compound and / or an easily vaporized carbon-containing liquid organic compound, wherein the carbon-containing gaseous organic compound can be one or more of methane, ethane, acetylene, propane, propylene, propyne, etc.; the easily vaporized carbon-containing liquid organic compound can be one or more of methanol, ethanol, acetone, petroleum ether; the second gas phase flow is hydrogen, and the third gas phase flow is argon.

[0033] Furthermore, according to some specific embodiments of the present invention, the volumetric flow rate ratio of the first gas phase flow, the second gas phase flow, and the third gas phase flow in the first growth process is: third gas phase flow / (second gas phase flow + third gas phase flow) = 0 to 0.7, preferably 0.4 to 0.6; first gas phase flow / (first gas phase flow + second gas phase flow) = 0.01 to 0.06, preferably 0.03 to 0.05.

[0034] Furthermore, according to some specific embodiments of the present invention, the first growth process operating parameters are as follows: deposition furnace pressure is 3000-10000 Pa, single filament power is 0.5-0.9 kW, filament temperature is 2200-2700 °C, substrate temperature is 750-1050 °C, and the distance between the filament and the substrate is 4-8 mm; preferably, the deposition furnace pressure is 4000-9000 Pa, single filament power is 0.6-0.8 kW, filament temperature is 2300-2600 °C, and substrate temperature is 800-950 °C.

[0035] Furthermore, according to some specific embodiments of the present invention, the first growth time is 120 to 600 min, preferably 240 to 360 min.

[0036] Furthermore, according to some specific embodiments of the present invention, the second processing step is as follows: stop the third gas phase flow, introduce the first gas phase flow and the second gas phase flow into the hot filament CVD diamond deposition furnace respectively, set the CVD diamond deposition furnace parameters to the second processing parameters, and run the second processing time.

[0037] Furthermore, according to some specific embodiments of the present invention, the volumetric flow rate ratio of the first gas phase flow and the second gas phase flow in the second processing is: first gas phase flow / (first gas phase flow + second gas phase flow) = 0.04 to 0.08, preferably 0.05 to 0.06.

[0038] Furthermore, according to some specific embodiments of the present invention, the second processing parameters are as follows: the deposition furnace pressure is 2000-4000 Pa, the power of a single filament is 0.7-1.0 kW, the filament temperature is 2200-2700 °C, the substrate temperature is 750-1050 °C, and the distance between the filament and the substrate is 4-8 mm; preferably, the deposition furnace pressure is 2500-3500 Pa, the power of a single filament is 0.75-0.85 kW, the filament temperature is 2300-2600 °C, and the substrate temperature is 800-950 °C.

[0039] Furthermore, according to some specific embodiments of the present invention, the second processing time is 10 to 60 minutes, preferably 20 to 30 minutes.

[0040] Furthermore, according to some specific embodiments of the present invention, the third transition process is as follows: a third gas phase flow is introduced, the first gas phase flow, the second gas phase flow, and the third gas phase flow are respectively fed into a hot-wire CVD diamond deposition furnace, the parameters of the CVD diamond deposition furnace are set as the parameters of the third transition process, and the third transition time is set.

[0041] Furthermore, according to some specific embodiments of the present invention, the third transition process parameters are: during the third transition time, the gas volume flow rate, deposition furnace pressure, single filament power, filament temperature, substrate temperature, and distance between the filament and the substrate are linearly changed from the second processing process parameters to the first growth process parameters.

[0042] Furthermore, according to some specific embodiments of the present invention, the third transition time is 20 to 120 minutes, preferably 30 to 60 minutes.

[0043] Furthermore, according to some specific embodiments of the present invention, the filament can be at least one of tantalum filament, tungsten filament, etc. The length and diameter of the filament are not limited in any way, as long as they are adapted to the size of the CVD deposition furnace and the substrate used.

[0044] Furthermore, according to some specific embodiments of the present invention, in step S3, a pressure load of 0.1 to 1 MPa is applied from top to bottom on the nucleation surface of the CVD diamond thick film. Specifically, a weight can be applied to the CVD diamond thick film and then placed in a vacuum furnace for welding.

[0045] Furthermore, according to some specific embodiments of the present invention, the vacuum degree of the vacuum furnace is set to 0.03Pa-0.001Pa, preferably 0.01Pa-0.001Pa.

[0046] Furthermore, according to some specific embodiments of the present invention, the welding temperature in the vacuum furnace during step S3 is 700–900°C.

[0047] The third aspect of the present invention provides the above-mentioned CVD diamond cutting teeth as cutting tools.

[0048] Furthermore, CVD diamond cutting teeth can be mass-produced into diamond drill bits for use in geological drilling applications such as oil drilling and deep well drilling.

[0049] The beneficial effects of the CVD diamond cutting teeth and their preparation method provided by this invention include one or a combination of the following:

[0050] 1. This invention is the first to achieve the production of CVD diamond cutting teeth with excellent wear resistance and high-temperature resistance through a welding process using CVD diamond thick film as raw material, thus endowing the CVD diamond cutting teeth with excellent overall performance.

[0051] 2. In this invention, by employing specific flux and welding process, a highly efficient connection between CVD diamond thick film and cemented carbide is achieved, and the connection strength meets the requirements for use, making it possible for CVD diamond thick film to be used as a cutting surface for geological exploration.

[0052] 3. In the CVD diamond thick film preparation method of this invention, "secondary nucleation" is achieved during the growth process by periodically introducing processing and transition processes. This effectively prevents the formation of a columnar crystal structure (thin at the bottom and coarse at the top) caused by the preferential, rapid, and long-term deposition of crystals in a certain direction, which is common in traditional CVD diamond thick film deposition processes. The provided CVD diamond thick film has uniform crystal cross-sectional dimensions and no columnar crystals, avoiding the internal stress caused by such a columnar crystal structure and improving the overall mechanical properties of the diamond film. The CVD diamond thick film provided by this invention exhibits 25% better wear resistance compared to conventional CVD diamond thick films.

[0053] 4. This invention increases the mean free path of methyl radicals by introducing argon gas during the deposition process, thereby increasing the effective concentration of methyl radicals. Through process control, it mitigates carbon buildup in the filament, effectively increases the single growth time, ensures the thickness of the diamond film, and obtains millimeter-scale CVD diamond thick films.

[0054] 5. The CVD diamond thick film provided by this invention does not contain any metal binders or metal catalysts compared with the PCD diamond commonly used in the field of geological exploration. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the CVD diamond cutting tooth structure described in this invention.

[0056] Figure 2 This is the case of heavy-load wet grinding of CVD diamond cutting teeth in Embodiment 1 of the present invention.

[0057] Figure 3 This is a scanning electron microscope image of the cross-section of the CVD diamond thick film in Embodiment 1 of the present invention.

[0058] Figure 4 This is a scanning electron microscope image of the CVD diamond thick film surface in Embodiment 1 of the present invention.

[0059] Figure 5 This is the Raman spectrum of the CVD diamond thick film in Example 1 of the present invention.

[0060] Figure 6 This is a scanning electron microscope image of the cross-section of the CVD diamond thick film in Comparative Example 1 of the present invention. Detailed Implementation

[0061] The method of the present invention will be further described in detail below through embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0062] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0063] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0064] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises," etc., shall be understood to include the stated elements or components without excluding other elements or other components. In this document, all numerical values ​​of parameters (e.g., quantities or conditions) shall be understood to be modified in all cases by the term "about," regardless of whether "about" actually precedes the numerical value.

[0065] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this instruction manual are based on weight, and the pressure is gauge pressure.

[0066] In the context of this specification, any two or more embodiments of the present invention can be arbitrarily combined, and the resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0067] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0068] The scanning electron microscope images of this invention were obtained using a Zeiss EVO MA 15.

[0069] The Raman spectra of this invention were obtained using LabRAM HR Evolution;

[0070] This invention utilizes the mechanical properties of CVD diamond thick films obtained through wear ratio reaction, and the testing methods refer to "JB / T-3235-1999".

[0071] Example 1

[0072] (1) Methane gas at a flow rate of 20 sccm, hydrogen gas at a flow rate of 500 sccm, and argon gas at a flow rate of 500 sccm were introduced into the CVD diamond deposition furnace respectively. The parameters of the CVD diamond deposition furnace were set as follows: deposition furnace pressure of 9000 Pa, single filament power of 0.8 kW, filament temperature of 2600 ℃, substrate temperature of 900 ℃, distance between filament and substrate of 8 mm, and first growth time of 300 min.

[0073] (2) Adjust the argon gas flow rate to 0 sccm, the methane gas flow rate to 60 sccm, and the hydrogen gas flow rate to 1000 sccm. Adjust the CVD diamond deposition furnace parameters as follows: deposition furnace pressure to 3500 Pa, single filament power to 0.85 kW, filament temperature to 2600 ℃, substrate temperature to 950 ℃, distance between filament and substrate to 4 mm, and run the second processing for 25 min.

[0074] (3) After step (2) is completed, the third transition time is set to 35 minutes. Within 35 minutes, the parameters in step (2) including methane gas flow rate, hydrogen gas flow rate, argon gas flow rate, deposition furnace pressure, single filament power, filament temperature, substrate temperature, and distance between filament and substrate are linearly changed to the parameters in step (1).

[0075] (4) Repeat steps (1)-(3) for 70 cycles to obtain a CVD diamond thick film.

[0076] (5) The diamond thick film is ground and polished on both sides and cut into a shape that matches the cemented carbide substrate.

[0077] (6) Prepare the raw materials for the welding transition layer by mixing 15% wt. diamond powder (0.1 μm), 10% wt. tungsten carbide micro powder (1 μm) and 75% wt. binder in a mass ratio, wherein the binder composition is silver (30% wt.), titanium (20% wt.), cobalt (35% wt.) and copper (15% wt.).

[0078] (7) Apply the welding transition layer material evenly to the diamond nucleation surface and the surface of the cemented carbide substrate, apply a pressure load from top to bottom and place it in a vacuum brazing furnace, control the vacuum degree of the vacuum brazing furnace to 0.001 Pa, raise the temperature from room temperature to 850°C at 1°C / min, keep the temperature constant for 10 min, and cool with the furnace.

[0079] Example 2

[0080] (1) Methane gas at a flow rate of 18 sccm, hydrogen gas at a flow rate of 335 sccm, and argon gas at a flow rate of 500 sccm were introduced into the CVD diamond deposition furnace. The parameters of the CVD diamond deposition furnace were set as follows: deposition furnace pressure of 6000 Pa, single filament power of 0.7 kW, filament temperature of 2400 ℃, substrate temperature of 850 ℃, distance between filament and substrate of 6 mm, and first growth time of 360 min.

[0081] (2) Adjust the argon gas flow rate to 0 sccm, the methane gas flow rate to 64 sccm, and the hydrogen gas flow rate to 1000 sccm. Adjust the CVD diamond deposition furnace parameters as follows: deposition furnace pressure to 3000 Pa, single filament power to 0.8 kW, filament temperature to 2350 ℃, substrate temperature to 850 ℃, distance between filament and substrate to 6 mm, and run the second processing for 30 min.

[0082] (3) After step (2) is completed, the third transition time is set to 60 minutes. Within 60 minutes, the parameters in step (2) including methane gas flow rate, hydrogen gas flow rate, argon gas flow rate, deposition furnace pressure, single filament power, filament temperature, substrate temperature, and distance between filament and substrate are linearly changed to the parameters in step (1).

[0083] (4) Repeat steps (1)-(3) for 60 cycles to obtain a CVD diamond thick film.

[0084] (5) The diamond thick film is ground and polished on both sides and cut into a shape that matches the cemented carbide substrate.

[0085] (6) Prepare the raw materials for the welding transition layer by mixing 20% ​​wt. diamond powder (1 μm), 15% wt. tungsten carbide micro powder (5 μm) and 65% wt. binder in a mass ratio, wherein the binder composition is silver (25% wt.), titanium (15% wt.), cobalt (40% wt.) and copper (20% wt.).

[0086] (7) Apply the welding transition layer material evenly to the diamond nucleation surface and the surface of the cemented carbide substrate, apply a pressure load from top to bottom and place it in a vacuum brazing furnace, control the vacuum degree of the vacuum brazing furnace to 0.005 Pa, raise the temperature from room temperature to 900℃ at 2℃ / min, keep the temperature constant for 10 min, and cool with the furnace.

[0087] Example 3

[0088] (1) Methane gas at a flow rate of 16 sccm, hydrogen gas at a flow rate of 800 sccm, and argon gas at a flow rate of 200 sccm were introduced into the CVD diamond deposition furnace. The parameters of the CVD diamond deposition furnace were set as follows: deposition furnace pressure of 6000 Pa, single filament power of 0.7 kW, filament temperature of 2400 ℃, substrate temperature of 850 ℃, distance between filament and substrate of 6 mm, and first growth time of 120 min.

[0089] (2) Adjust the argon gas flow rate to 0 sccm, the methane gas flow rate to 60 sccm, and the hydrogen gas flow rate to 1000 sccm. Adjust the CVD diamond deposition furnace parameters as follows: deposition furnace pressure to 2000 Pa, single filament power to 1.0 kW, filament temperature to 2700 ℃, substrate temperature to 1050 ℃, distance between filament and substrate to 4 mm, and run the second processing for 25 min.

[0090] (3) After step (2) is completed, the third transition time is set to 35 min. Within 35 min, the parameters included in step (2), such as methane gas flow rate, hydrogen gas flow rate, argon gas flow rate, deposition furnace pressure, single filament power, filament temperature, substrate temperature, and distance between filament and substrate, are linearly changed to the parameters shown in step (1).

[0091] (4) Repeat steps (1)-(3) for 120 cycles to obtain a CVD diamond thick film.

[0092] (5) The diamond thick film is ground and polished on both sides and cut into a shape that matches the cemented carbide substrate.

[0093] (6) Prepare the raw materials for the welding transition layer by mixing 18% wt. diamond powder (10 μm), 13% wt. tungsten carbide micro powder (10 μm) and 69% wt. binder in a mass ratio, wherein the binder composition is silver (45% wt.), titanium (15% wt.), cobalt (30% wt.) and copper (10% wt.).

[0094] (7) Apply the welding transition layer material evenly to the diamond nucleation surface and the surface of the cemented carbide substrate, apply a pressure load from top to bottom and place it in a vacuum brazing furnace, control the vacuum degree of the vacuum brazing furnace to 0.01 Pa, raise the temperature from room temperature to 700°C at 1°C / min, keep the temperature constant for 10 min, and cool with the furnace.

[0095] Example 4

[0096] (1) Methane gas at a flow rate of 20 sccm, hydrogen gas at a flow rate of 500 sccm, and argon gas at a flow rate of 500 sccm were introduced into the CVD diamond deposition furnace respectively. The parameters of the CVD diamond deposition furnace were set as follows: deposition furnace pressure of 10000 Pa, single filament power of 0.9 kW, filament temperature of 2650 ℃, substrate temperature of 1000 ℃, distance between filament and substrate of 8 mm, and first growth time of 300 min.

[0097] (2) Adjust the argon gas flow rate to 0 sccm, the methane gas flow rate to 32 sccm, and the hydrogen gas flow rate to 750 sccm. Adjust the CVD diamond deposition furnace parameters as follows: deposition furnace pressure to 3000 Pa, single filament power to 0.8 kW, filament temperature to 2350 ℃, substrate temperature to 850 ℃, distance between filament and substrate to 6 mm, and run the second processing for 10 min.

[0098] (3) After step (2) is completed, the third transition time is set to 35 minutes. Within 35 minutes, the parameters in step (2) including ethane gas flow rate, hydrogen gas flow rate, argon gas flow rate, deposition furnace pressure, single filament power, filament temperature, substrate temperature, and distance between filament and substrate are linearly changed to the parameters in step (1).

[0099] (4) Repeat steps (1)-(3) for 70 cycles to obtain a CVD diamond thick film.

[0100] (5) The diamond thick film is ground and polished on both sides and cut into a shape that matches the cemented carbide substrate.

[0101] (6) Prepare the raw materials for the welding transition layer by mixing 18% wt. diamond powder (10 μm), 13% wt. tungsten carbide micro powder (10 μm) and 69% wt. binder in a mass ratio, wherein the binder composition is silver (25% wt.), titanium (35% wt.), cobalt (30% wt.) and copper (10% wt.).

[0102] (7) Apply the welding transition layer material evenly to the diamond nucleation surface and the surface of the cemented carbide substrate, apply a pressure load from top to bottom and place it in a vacuum brazing furnace, control the vacuum degree of the vacuum brazing furnace to 0.01 Pa, raise the temperature from room temperature to 800°C at 1°C / min, keep the temperature constant for 10 min, and cool with the furnace.

[0103] Comparative Example 1

[0104] (1) Methane gas was introduced into the CVD diamond deposition furnace at a flow rate of 20 sccm and hydrogen gas at a flow rate of 1000 sccm respectively. The parameters of the CVD diamond deposition furnace were set as follows: deposition furnace pressure was 9000 Pa, single filament power was 0.8 kW, filament temperature was 2600 ℃, substrate temperature was 900 ℃, distance between filament and substrate was 8 mm, and the first growth time was 300 min.

[0105] (2) Adjust the methane gas flow rate to 60 sccm and the hydrogen gas flow rate to 1000 sccm. Adjust the CVD diamond deposition furnace parameters as follows: deposition furnace pressure to 3500 Pa, single filament power to 0.85 kW, filament temperature to 2600 ℃, substrate temperature to 950 ℃, distance between filament and substrate to 4 mm, and run the second processing time to 25 min.

[0106] (3) After step (2) is completed, the third transition time is set to 35 min. Within 35 min, the parameters in step (2) such as methane gas flow rate, hydrogen gas flow rate, argon gas flow rate, deposition furnace pressure, single filament power, filament temperature, substrate temperature, and distance between filament and substrate are linearly changed to the parameters in step (1).

[0107] (4) Repeat steps (1)-(3) for 70 cycles to obtain a CVD diamond thick film.

[0108] (5) The diamond thick film is ground and polished on both sides and cut into a shape that matches the cemented carbide substrate.

[0109] (6) Prepare the raw materials for the welding transition layer by mixing 15% wt. diamond powder (0.1 μm), 10% wt. tungsten carbide micro powder (1 μm) and 75% wt. binder in a mass ratio, wherein the binder composition is silver (30% wt.), titanium (20% wt.), cobalt (35% wt.) and copper (15% wt.).

[0110] (7) Apply the welding transition layer material evenly to the diamond nucleation surface and the surface of the cemented carbide substrate, apply a pressure load from top to bottom and place it in a vacuum brazing furnace, control the vacuum degree of the vacuum brazing furnace to 0.001 Pa, raise the temperature from room temperature to 850°C at 1°C / min, keep the temperature constant for 10 min, and cool with the furnace.

[0111] Comparative Example 2

[0112] (1) Methane gas at a flow rate of 20 sccm, hydrogen gas at a flow rate of 500 sccm, and argon gas at a flow rate of 500 sccm were introduced into the CVD diamond deposition furnace respectively. The parameters of the CVD diamond deposition furnace were set as follows: deposition furnace pressure of 9000 Pa, single filament power of 0.8 kW, filament temperature of 2600 ℃, substrate temperature of 900 ℃, distance between filament and substrate of 8 mm, and first growth time of 24000 min to obtain CVD diamond thick film.

[0113] (2) The diamond thick film is ground and polished on both sides and cut into a shape that matches the cemented carbide substrate.

[0114] (3) Prepare the raw materials for the welding transition layer by mixing 15% wt. diamond powder (0.1 μm), 10% wt. tungsten carbide micro powder (1 μm) and 75% wt. binder in a mass ratio, wherein the binder composition is silver (30% wt.), titanium (20% wt.), cobalt (35% wt.) and copper (15% wt.).

[0115] (4) Apply the welding transition layer material evenly to the diamond nucleation surface and the surface of the cemented carbide substrate, apply a pressure load from top to bottom and place it in a vacuum brazing furnace, control the vacuum degree of the vacuum brazing furnace to 0.001 Pa, raise the temperature from room temperature to 850°C at 1°C / min, keep the temperature constant for 10 min, and cool with the furnace.

[0116] Comparative Example 3

[0117] (1) Methane gas at a flow rate of 20 sccm, hydrogen gas at a flow rate of 500 sccm, and argon gas at a flow rate of 500 sccm were introduced into the CVD diamond deposition furnace respectively. The parameters of the CVD diamond deposition furnace were set as follows: deposition furnace pressure of 9000 Pa, single filament power of 0.8 kW, filament temperature of 2600 ℃, substrate temperature of 900 ℃, distance between filament and substrate of 8 mm, and first growth time of 300 min.

[0118] (2) Adjust the argon gas flow rate to 0 sccm, the methane gas flow rate to 60 sccm, and the hydrogen gas flow rate to 1000 sccm. Adjust the CVD diamond deposition furnace parameters as follows: deposition furnace pressure to 3500 Pa, single filament power to 0.85 kW, filament temperature to 2600 ℃, substrate temperature to 950 ℃, distance between filament and substrate to 4 mm, and run the second processing for 25 min.

[0119] (3) Repeat steps (1)-(2) for 70 cycles to obtain a CVD diamond thick film.

[0120] (4) The diamond thick film is ground and polished on both sides and cut into a shape that matches the cemented carbide substrate.

[0121] (5) Prepare the raw materials for the welding transition layer by mixing 15% wt. diamond powder (0.1 μm), 10% wt. tungsten carbide micro powder (1 μm) and 75% wt. binder in a mass ratio, wherein the binder composition is silver (30% wt.), titanium (20% wt.), cobalt (35% wt.) and copper (15% wt.).

[0122] (6) Apply the welding transition layer material evenly to the diamond nucleation surface and the surface of the cemented carbide substrate, apply a pressure load from top to bottom and place it in a vacuum brazing furnace, control the vacuum degree of the vacuum brazing furnace to 0.001 Pa, raise the temperature from room temperature to 850°C at 1°C / min, keep the temperature constant for 10 min, and cool with the furnace.

[0123] Comparative Example 4

[0124] (1) Methane gas at a flow rate of 20 sccm, hydrogen gas at a flow rate of 500 sccm, and argon gas at a flow rate of 500 sccm were introduced into the CVD diamond deposition furnace respectively. The parameters of the CVD diamond deposition furnace were set as follows: deposition furnace pressure of 9000 Pa, single filament power of 0.8 kW, filament temperature of 2600 ℃, substrate temperature of 900 ℃, distance between filament and substrate of 8 mm, and first growth time of 300 min.

[0125] (2) Adjust the argon gas flow rate to 0 sccm, the methane gas flow rate to 60 sccm, and the hydrogen gas flow rate to 1000 sccm. Adjust the CVD diamond deposition furnace parameters as follows: deposition furnace pressure to 3500 Pa, single filament power to 0.85 kW, filament temperature to 2600 ℃, substrate temperature to 950 ℃, distance between filament and substrate to 4 mm, and run the second processing for 25 min.

[0126] (3) After step (2) is completed, the third transition time is set to 35 minutes. Within 35 minutes, the parameters in step (2) including methane gas flow rate, hydrogen gas flow rate, argon gas flow rate, deposition furnace pressure, single filament power, filament temperature, substrate temperature, and distance between filament and substrate are linearly changed to the parameters in step (1).

[0127] (4) Repeat steps (1)-(3) for 70 cycles to obtain a CVD diamond thick film.

[0128] (5) The diamond thick film is ground and polished on both sides and cut into a shape that matches the cemented carbide substrate.

[0129] (6) Prepare the raw materials for the welding transition layer by mixing 10% wt. of tungsten carbide micro powder (1 μm) and 90% wt. of binder in a mass ratio, wherein the binder consists of silver (30% wt.), titanium (20% wt.), cobalt (35% wt.), and copper (15% wt.).

[0130] (7) Apply the welding transition layer material evenly to the diamond nucleation surface and the surface of the cemented carbide substrate, apply a pressure load from top to bottom and place it in a vacuum brazing furnace, control the vacuum degree of the vacuum brazing furnace to 0.001 Pa, raise the temperature from room temperature to 850°C at 1°C / min, keep the temperature constant for 10 min, and cool with the furnace.

[0131] Evaluation Test

[0132] The CVD diamond thick films obtained in Examples 1-4 and Comparative Examples 1-4 were subjected to wear ratio tests. The wear ratio test conditions were as follows: before the test, the samples were uniformly laser-cut to [a specific size / section]. Double-sided grinding and polishing were performed. The nucleation surface was used as the working surface, the grinding wheel hardness was 3.7, the initial rotation speed was 25 m / s, and all other test conditions and procedures were performed in accordance with "JB / T-3235-1999".

[0133] The CVD diamond cutting teeth obtained in Examples 1-4 and Comparative Examples 1-4 were subjected to heavy-load wet grinding tests. The heavy-load wet grinding test conditions were as follows: the complete cutting tooth was fixed on a fixture, with the cutting surface in contact with natural granite, and a load of 1000 N was applied between them. The granite was rotated at 5 rpm, and flowing water was passed through the contact surface for cooling. Product quality was measured by the area of ​​the CVD diamond thick film grinding joint after 50 rotations of the granite.

[0134] Table 1. Test results of CVD diamond films in each embodiment and comparative example.

[0135]

[0136]

[0137] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A CVD diamond cutting tooth, characterized in that: The CVD diamond cutting tooth comprises a CVD diamond thick film, a weld transition layer, and a cemented carbide substrate, wherein the thickness of the CVD diamond thick film is greater than or equal to 0.5 mm, and the I of the CVD diamond thick film... G / I D <0.2, where the carbon atoms are characterized by Raman spectroscopy, I G This indicates that SP 2 Characteristic peak intensity of hybrid graphite phase crystals, I D This indicates that SP 3 The characteristic peak intensity of the hybrid diamond phase; the weld transition layer includes diamond powder, tungsten carbide particles and binder. Based on the total weight of the weld transition layer, the mass percentage of diamond powder is 10% to 30%, the mass percentage of tungsten carbide particles is 5% to 25%, and the mass percentage of binder is 45% to 85%. The binder is a metallic binder.

2. The CVD diamond cutting tooth according to claim 1, characterized in that: The thickness of CVD diamond thick film is greater than or equal to 1.0 mm.

3. The CVD diamond cutting tooth according to claim 1, characterized in that: The thickness of CVD diamond thick film is 1.0 to 2.0 mm.

4. The CVD diamond cutting tooth according to claim 1, characterized in that: The CVD diamond thick film has a micron-sized polycrystalline structure with a crystal size of 10–300 μm. The crystal morphology of the micron-sized polycrystalline structure is one or more of the following: cubic, octahedral, truncated octahedral, and faceted. When it includes two or more crystal morphologies, it is a disordered non-preferred orientation crystal composed of two or more crystal morphologies.

5. The CVD diamond cutting tooth according to claim 4, characterized in that: The crystal morphology of the micron-sized polycrystalline structure is octahedral.

6. The CVD diamond cutting tooth according to claim 1, characterized in that: CVD diamond thick film I G / I D <0.

15.

7. The CVD diamond cutting tooth according to claim 1, characterized in that: Based on the total weight of the weld transition layer, the mass percentage of diamond powder is 15%–20%; the mass percentage of tungsten carbide particles is 10%–15%; and the mass percentage of binder is 65%–75%.

8. The CVD diamond cutting tooth according to claim 1, characterized in that: The diamond powder has a particle size of 0.1–10 μm, and / or the tungsten carbide particles have a particle size of 1–10 μm.

9. The CVD diamond cutting tooth according to claim 1, characterized in that: The binders include silver, titanium, cobalt and copper. Based on the total weight of the binders, the mass percentage of silver is 25% to 45%, the mass percentage of titanium is 15% to 35%, the mass percentage of cobalt is 30% to 40%, and the mass percentage of copper is 10% to 20%.

10. The CVD diamond cutting tooth according to claim 1, characterized in that: The cemented carbide substrate includes, but is not limited to, tungsten-cobalt cemented carbide and tungsten-titanium-cobalt cemented carbide.

11. A method for preparing diamond cutting teeth, the method comprising the following steps: S1, a thick diamond film is prepared, and then ground and polished to a mirror finish, followed by laser cutting into the target shape; the preparation method of the thick diamond film includes the following steps: (1) A CVD diamond film is obtained on a substrate using a first growth process; the first growth process involves passing a first gas phase flow, a second gas phase flow, and a third gas phase flow into a hot-wire CVD diamond deposition furnace, setting the CVD diamond deposition furnace parameters to the first growth process parameters, and running for a first growth time; the first gas phase flow is one or more of a carbon-containing gaseous organic compound and / or an easily vaporized carbon-containing liquid organic compound, wherein the carbon-containing gaseous organic compound is one or more of methane, ethane, acetylene, propane, propylene, and propyne; the easily vaporized carbon-containing liquid organic compound is one or more of methanol, ethanol, acetone, and petroleum ether; the second gas phase flow is hydrogen, and the third gas phase flow is argon. (2) Then, the unmodified CVD diamond film obtained in step (1) is modified using the second processing technology; The second processing step involves stopping the third gas phase flow, introducing the first and second gas phase flows into the hot-wire CVD diamond deposition furnace, setting the CVD diamond deposition furnace parameters to the parameters of the second processing step, and running the second processing for the specified duration. (3) Then, a third transition process is used to perform a transition treatment on the modified CVD diamond film obtained in step (2); The third transition process involves introducing a third gas phase flow. The first, second, and third gas phase flows are respectively fed into a hot-wire CVD diamond deposition furnace. The parameters of the CVD diamond deposition furnace are set as the parameters of the third transition process, and the third transition time is run. (4) Repeat steps (1) to (3) to obtain a CVD diamond thick film; S2, the welding transition layer raw materials are mixed in proportion and uniformly coated on the growth surface of the CVD diamond thick film and the surface of the cemented carbide substrate; the welding transition layer raw materials include diamond powder, tungsten carbide particles and binder. Based on the total weight of the welding transition layer, the mass percentage of diamond powder is 10% to 30%, the mass percentage of tungsten carbide particles is 5% to 25%, and the mass percentage of binder is 45% to 85%. The binder is a metal binder. S3, the growth surface of the CVD diamond thick film is combined with the surface of the cemented carbide substrate, and then a pressure load from top to bottom is applied to the nucleation surface of the CVD diamond thick film. Then, it is placed in a vacuum furnace for welding treatment to obtain CVD diamond cutting teeth.

12. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The volumetric flow rate ratios of the first gas phase flow, the second gas phase flow, and the third gas phase flow in the first growth process are: third gas phase flow / (second gas phase flow + third gas phase flow) = 0 to 0.7; first gas phase flow / (first gas phase flow + second gas phase flow) = 0.01 to 0.

06.

13. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The volumetric flow rate ratios of the first gas phase flow, the second gas phase flow, and the third gas phase flow in the first growth process are: third gas phase flow / (second gas phase flow + third gas phase flow) = 0.4~0.6; first gas phase flow / (first gas phase flow + second gas phase flow) = 0.03~0.

05.

14. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The first growth process operating parameters are: deposition furnace pressure of 3000-10000 Pa, single filament power of 0.5-0.9 kW, filament temperature of 2200-2700℃, substrate temperature of 750-1050℃, and distance between filament and substrate of 4-8 mm.

15. The method for preparing diamond cutting teeth according to claim 14, characterized in that: The first growth process operating parameters are: deposition furnace pressure of 4000-9000 Pa, single filament power of 0.6-0.8 kW, filament temperature of 2300-2600℃, and substrate temperature of 800-950℃.

16. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The first growth period is 120–600 min.

17. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The first growth period is 240–360 minutes.

18. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The volumetric flow rate ratio of the first gas phase flow and the second gas phase flow in the second processing technology is: first gas phase flow / (first gas phase flow + second gas phase flow) = 0.04 to 0.

08.

19. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The volumetric flow rate ratio of the first gas phase flow and the second gas phase flow in the second processing technology is: first gas phase flow / (first gas phase flow + second gas phase flow) = 0.05~0.

06.

20. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The second processing parameters are: deposition furnace pressure of 2000-4000 Pa, single filament power of 0.7-1.0 kW, filament temperature of 2200-2700 ℃, substrate temperature of 750-1050 ℃, and distance between filament and substrate of 4-8 mm.

21. The method for preparing diamond cutting teeth according to claim 20, characterized in that: The second processing parameters are: deposition furnace pressure of 2500-3500 Pa, single filament power of 0.75-0.85 kW, filament temperature of 2300-2600 °C, and substrate temperature of 800-950 °C.

22. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The second processing time is 10–60 minutes.

23. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The second processing time is 20–30 minutes.

24. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The third transition process parameters are: during the third transition period, the gas volume flow rate, deposition furnace pressure, single filament power, filament temperature, substrate temperature, and distance between the filament and the substrate change linearly from the second processing process parameters to the first growth process parameters.

25. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The third transition duration is 20–120 minutes.

26. The method for preparing diamond cutting teeth according to claim 11, characterized in that: The third transition time is 30–60 minutes.

27. The method for preparing diamond cutting teeth according to claim 11, characterized in that: In step S3, a pressure load of 0.1 to 1 MPa is applied from top to bottom on the nucleation surface of the CVD diamond thick film.

28. The method for preparing diamond cutting teeth according to claim 11, characterized in that: In step S3, the welding process is carried out in a vacuum furnace at a temperature of 700–900°C.

29. The CVD diamond cutting teeth according to any one of claims 1-10 or the CVD diamond cutting teeth obtained by the preparation method according to any one of claims 11-28 are used as cutting tools.

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