CVD diamond self-supporting film cutting element and manufacturing method and application thereof

Abstract

The invention discloses a CVD diamond self-supporting film cutting element and a manufacturing method and application thereof. The CVD diamond self-supporting film cutting element comprises a CVD diamond self-supporting film, a welding transition layer and a hard alloy substrate. The CVD diamond self-supporting film comprises NCD layers and MCD layers, wherein the NCD layers and the MCD layers are sequentially and alternately arranged. The preparation method comprises the steps that firstly, MCD layers and NCD layers are alternately deposited on a base body to form a CVD diamond self-supporting film, then the prepared CVD diamond self-supporting film, a welding transition layer and a hard alloy substrate are sequentially arranged from top to bottom, and pressure loads are applied to the diamond self-supporting film from top to bottom; and then welding the composite material in a vacuum furnace to obtain the CVD diamond self-supporting film cutting element. Through the synergistic effect of the CVD diamond self-supporting film, the welding transition layer and the hard alloy substrate, the whole CVD diamond self-supporting film cutting element is endowed with excellent wear resistance and high temperature resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of superhard composite materials, and in particular relates to a high-performance CVD diamond cutting element and a preparation method thereof. Background Art

[0002] The commonly used diamond cutting element at present is polycrystalline diamond composite sheet (Polycrystalline Diamond Compacts, referred to as PDC composite sheet), which is a superhard composite material composed of a cemented carbide substrate and polycrystalline diamond. The specific preparation method is to spread diamond powder on the cemented carbide substrate and synthesize it under high temperature and high pressure conditions. Under high temperature and high pressure conditions, metal components such as Co, Ni, and Fe in the cemented carbide substrate dissolve and diffuse into the diamond powder layer, promote the recrystallization growth of diamond particles, and realize the bonding between diamond particles and the connection between the diamond layer and the cemented carbide substrate layer. PDC composite sheets have both the wear resistance of diamond and the toughness of cemented carbide, and are widely used in the field of petroleum geological exploration.

[0003] PDC composite sheets have excellent mechanical properties, but their high temperature resistance is poor. In the finished PDC composite sheets, there are a large number of residual metal components (mainly Co, Ni, and Fe) between the diamond particles and between the diamond layer and the cemented carbide layer. During the high-speed cutting and grinding process of PDC composite sheets, the surface temperature can reach 700°C, and the local temperature even exceeds 1000°C. Under such high temperature conditions, the residual metal elements will catalyze the transformation of diamond to graphite; on the other hand, the thermal expansion coefficient of the residual metal is quite different from that of diamond. The difference in volume expansion between the two at high temperatures produces large stress, which causes micro cracks to form in the diamond layer, greatly reducing the quality of the PDC composite sheet. Improving the high temperature resistance of diamond cutting elements and avoiding their "thermal failure" at high temperatures is currently a hot topic in the industry. A commonly used method is the "acid removal of cobalt" technology, which uses strong acid to dissolve the residual metal between the diamond particles, but this will cause an increase in internal defects in the diamond layer, and then the mechanical properties will decrease.

[0004] Almost all the physical and chemical properties of diamonds prepared by Chemical Vapor Deposition (CVD) are the same as those of natural high-quality type IIa diamond single crystals (diamonds), and it is the most promising process for artificial synthesis of diamonds. It contains 100% diamond elements, does not contain metal binders, and will not produce thermal failure at high temperatures. If the CVD diamond film is prepared to a certain thickness and combined with a cemented carbide substrate to form a cutting element, it will be a great change and update to the existing diamond cutting elements.

[0005] Diamond synthesized by CVD can be divided into diamond thin film and diamond thick film according to thickness. Generally speaking, diamond thick film is more than 0.5 mm thick, and only thick film can be used independently as a cutting tooth. At present, the difficulties in preparing cutting elements by combining CVD diamond thick film with cemented carbide substrate are: (1) the quality of thick film is low. As the thickness of diamond film increases, the proportion of internal microscopic defects increases and the mechanical properties decrease; (2) the weldability of CVD diamond film and metal substrate is poor, and the welding strength cannot meet the use requirements.

[0006] CN201710513068.3 discloses a polycrystalline diamond composite sheet and a preparation method thereof, which reduces the problem of "thermal damage" of the PDC composite sheet during use by adding a transition layer and a CVD diamond layer on the basis of the original PDC composite sheet. However, the polycrystalline diamond of the invention still contains metal elements and does not fundamentally solve the problem. Summary of the invention

[0007] The main purpose of the present invention is to provide a CVD diamond self-supporting film cutting element and its preparation method and application. First, a multi-layer composite structure CVD diamond self-supporting film composed of a nano-grain size film with smaller particles (hereinafter referred to as NCD) and a micron-grain size film with larger particles (hereinafter referred to as MCD) arranged alternately in sequence is prepared by a hot wire CVD method, and further the CVD diamond film is effectively connected to a cemented carbide substrate by adjusting the welding process and the composition of the flux. The CVD diamond self-supporting film cutting element of the present invention can be used in batches to form drill bits for oil extraction and geological exploration.

[0008] The first aspect of the present invention provides a CVD diamond self-supporting film cutting element, which comprises a CVD diamond self-supporting film, a welding transition layer and a cemented carbide substrate; the CVD diamond self-supporting film comprises an NCD layer and an MCD layer arranged alternately in sequence; the diamond grain size of the NCD layer is <1μm, and the diamond grain size of the MCD layer is between 10 and 100μm.

[0009] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the thickness of the CVD diamond self-supporting film is not less than 1.0 mm, preferably 1.2 to 2.0 mm.

[0010] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the shape and size of the CVD diamond self-supporting film match the cemented carbide substrate, and can be one or more of a cylindrical shape and a multi-prism shape, preferably a cylindrical shape, and more preferably a cylindrical shape with a diameter of 10 to 20 mm. The CVD diamond self-supporting film generally needs to be ground and polished to a mirror surface, and then cut into a target shape by laser.

[0011] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the MCD layer is a diamond polycrystalline structure, and the crystals of the polycrystalline structure are one or more of the following shapes: cubic morphology, octahedral morphology, truncated octahedral morphology, and faceted morphology, preferably an octahedral morphology; further, when it includes more than two crystal morphologies, it is a chaotic non-preferentially oriented crystal composed of more than two crystal morphologies.

[0012] Furthermore, in the above CVD diamond self-supporting film cutting element, the diamond crystals of the MCD layer are tightly connected to each other through DD bonds, and there are no obvious grain boundaries between the crystals.

[0013] Furthermore, in the above CVD diamond self-supporting film cutting element, the carbon in the diamond of the MCD layer is SP 3 Hybrid diamond phase is dominant, Raman spectroscopy characterization, SP 2 Characteristic peak intensity I of hybrid graphite phase crystal G and SP3 hybrid diamond phase characteristic peak intensity I D The ratio is I G / I D <0.3, preferably 1 G / I D <0.25.

[0014] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the NCD layer is a diamond polycrystalline structure, and the crystals of the polycrystalline structure are one or more of the following shapes: cubic morphology, octahedral morphology, truncated octahedral morphology, and faceted morphology. Further, when it includes more than two crystal morphologies, it is a chaotic crystal with no preferred orientation composed of more than two crystal morphologies; preferably, it is a chaotic crystal with no preferred orientation composed of more than two crystal morphologies.

[0015] Furthermore, in the above CVD diamond self-supporting film cutting element, there are obvious grain boundaries between the diamond crystals in the NCD layer, and the grain boundaries are formed by SP 2 Hybridized graphite phase filled with carbon atoms.

[0016] Furthermore, in the above CVD diamond self-supporting film cutting element, the carbon in the diamond of the NCD layer is SP 3 Hybrid diamond phase and SP 2 The hybrid graphite phase is uniformly mixed; in Raman spectroscopy characterization, SP 2 Characteristic peak intensity I of hybrid graphite phase crystal G and SP 3 Characteristic peak intensity of hybrid diamond phase I D The ratio is I G / I D Between 0.4 and 1.0, preferably between 0.5 and 0.8, and SP3 The characteristic peaks of hybrid diamond phase are sharp.

[0017] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the thickness of the MCD layer is 10 to 100 μm, and the thickness of the NCD layer is 1 to 20 μm.

[0018] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the welding transition layer is an intermediate layer connecting the CVD diamond self-supporting film and the cemented carbide substrate, and its main function is to ensure the effective connection and heat conduction between the CVD diamond self-supporting film and the cemented carbide substrate, so that the CVD diamond self-supporting film and the cemented carbide substrate will not separate and fail during the use of the cutting element as a whole.

[0019] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the welding transition layer includes diamond powder, tungsten carbide particles and a binder. Based on the total weight of the welding transition layer, the mass percentage of the diamond powder is 10% to 30%, preferably 15% to 20%; the mass percentage of the tungsten carbide particles is 5% to 25%, preferably 10% to 15%; the mass percentage of the binder is 45% to 85%, preferably 65% ​​to 75%.

[0020] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the particle size of the diamond powder is 0.1 to 10 μm, and the particle size of the tungsten carbide particles is 1 to 10 μm.

[0021] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the binder is a metal binder, including silver, titanium, cobalt and copper. 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%.

[0022] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the cemented carbide substrate can be selected from any one or more of the existing cemented carbides in the art, including but not limited to tungsten-cobalt cemented carbide, tungsten-titanium-cobalt cemented carbide, etc.

[0023] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element, the cemented carbide substrate is processed into a shape and size matching the CVD diamond self-supporting film.

[0024] The second aspect of the present invention provides a method for preparing a CVD diamond self-supporting film cutting element, the method comprising: firstly, alternately depositing MCD layers and NCD layers on a substrate to form a CVD diamond self-supporting film, then sequentially arranging the prepared CVD diamond self-supporting film, a welding transition layer and a cemented carbide substrate from top to bottom, applying a pressure load from top to bottom on the diamond self-supporting film, and then using a programmed temperature rising process to heat the above-mentioned composite material to a high temperature in a vacuum furnace for welding, thereby obtaining the CVD diamond self-supporting film cutting element.

[0025] A second aspect of the present invention provides a method for preparing a CVD diamond self-supporting film cutting element, the method comprising the following steps:

[0026] (1) depositing an MCD layer on a substrate by a first deposition process, wherein the first deposition process is to respectively pass a first gas phase flow and a second gas phase flow into a CVD diamond deposition furnace, set a deposition parameter of the CVD diamond deposition furnace to a first deposition process parameter, and run a first deposition time;

[0027] (2) using a first transition process to perform transition processing on the deposition process in step (1), wherein the first transition process is to introduce a third gas phase flow, adjust the deposition parameters of the CVD diamond deposition furnace to the first transition process parameters, and run the first transition time; when the first transition time ends, the CVD diamond deposition furnace enters the second deposition process;

[0028] (3) using a second deposition process to continue depositing the NCD layer on the MCD layer, the second deposition process is to respectively pass the first gas phase flow, the second gas phase flow and the third gas phase flow into the CVD diamond deposition furnace, set the deposition parameters of the CVD diamond deposition furnace to the second deposition process parameters, and run the second deposition time;

[0029] (4) using a second transition process to perform transition processing on the deposition process in step (3), wherein the second transition process is to reduce or shut down the third gas phase flow, adjust the deposition parameters of the CVD diamond deposition furnace to the second transition process parameters, and run the second transition time; when the second transition time ends, the CVD diamond deposition furnace enters the first deposition process;

[0030] (5) Repeating steps (1) to (4) until the thickness of the CVD diamond self-supporting film meets the requirements;

[0031] (6) mixing the welding transition layer raw materials in proportion and uniformly coating them on the growth surface of the CVD diamond self-supporting film and the surface of the cemented carbide substrate;

[0032] (7) combining the growth surface of the CVD diamond self-supporting film with the surface of the cemented carbide substrate, then applying a pressure load from top to bottom on the nucleation surface of the CVD diamond self-supporting film, and then placing it in a vacuum furnace for welding to obtain a CVD diamond self-supporting film cutting element

[0033] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element preparation method, the first gas phase flow in step (1) can be one or more of gaseous organic matter containing carbon elements and / or liquid organic matter containing carbon elements that are easily gasified, and the second gas phase flow in step (1) is hydrogen. In a further case, the gaseous organic matter containing carbon elements can be selected from one or more of methane, ethane, acetylene, propane, propylene, propyne, etc.; the liquid organic matter containing carbon elements that are easily gasified can be selected from one or more of methanol, ethanol, acetone, and petroleum ether.

[0034] Furthermore, in the above-mentioned method for preparing a CVD diamond self-supporting film cutting element, the third gas phase flow in step (2) is argon.

[0035] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element preparation method, the first deposition process parameters in step (1) are as follows: the deposition furnace pressure is 2000~5000Pa, the single filament power is 0.8~1.2kW, the filament temperature is 2200~2700℃, the substrate temperature is 750~1050℃, and the distance between the filament and the substrate is 4~8mm; preferably, the first deposition process parameters are as follows: the deposition furnace pressure is 3000~4000Pa, the single filament power is 0.85~0.95kW, the single filament temperature is 2200~2600℃, and the substrate temperature is 800~950℃.

[0036] Furthermore, in the above-mentioned method for preparing a CVD diamond self-supporting film cutting element, the volume flow ratio of the first gas phase flow to the second gas phase flow in step (1) is generally 1:50 to 1:20, preferably 3:100 to 1:25.

[0037] Furthermore, in the above-mentioned method for preparing the CVD diamond self-supporting film cutting element, the first deposition time in step (1) is 120 to 600 minutes, preferably 240 to 360 minutes.

[0038] Furthermore, in the above-mentioned method for preparing a CVD diamond self-supporting film cutting element, the third gas phase flow in step (2) is argon.

[0039] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element preparation method, the first transition time in step (2) is 10 to 60 minutes, preferably 20 to 40 minutes; the first transition process is that within the first transition time, the deposition furnace pressure, single filament power, and gas phase flow volume flow rate linearly change to the parameters required for the second deposition process.

[0040] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element preparation method, the second deposition process parameters in step (3) are: deposition furnace pressure 6000~15000Pa, single filament power 0.3~0.7kW, filament temperature 2200~2700℃, substrate temperature 700~1050℃, and the distance between the filament and the substrate is 4~8mm; preferably, the deposition furnace pressure is 8000~13000Pa, the single filament power is 0.45~0.6kW, the single filament temperature is 2300~2600℃, and the substrate temperature is 750~850℃.

[0041] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element preparation method, in step (3), the volume flow ratio of the first gas phase flow, the second gas phase flow and the third gas phase flow is as follows: first gas phase flow / (first gas phase flow + second gas phase flow) = 0.01 to 0.3, preferably 0.04 to 0.2; third gas phase flow / (second gas phase flow + third gas phase flow) = 0.5 to 1, preferably 0.9 to 1.

[0042] Furthermore, in the above-mentioned method for preparing the CVD diamond self-supporting film cutting element, the second deposition time in step (3) is 120 to 1440 minutes, preferably 240 to 360 minutes.

[0043] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element preparation method, the second transition time in step (4) is 10 to 60 minutes, preferably 20 to 40 minutes; the second transition process is that within the second transition time, the deposition furnace pressure, single filament power, and gas phase flow volume flow rate linearly change to the parameters required for the first deposition process.

[0044] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element preparation method, the substrate can be selected as needed, and can be at least one of metal molybdenum, silicon, tungsten, titanium, graphite, etc. The shape of the substrate can be any shape, and the size of the substrate is not limited.

[0045] Furthermore, in the above-mentioned method for preparing the CVD diamond self-supporting film cutting element, the filament can be at least one of tantalum wire, tungsten wire, etc. The length and diameter of the filament are not limited and can be adapted to the size of the CVD deposition furnace and substrate used.

[0046] Furthermore, in the above-mentioned method for preparing the CVD diamond self-supporting film cutting element, the specific value of the pressure load applied from top to bottom on the nucleation surface of the CVD diamond self-supporting film in step (7) is 0.1 to 1 MPa, and the specific operation method is to apply a heavy object on the CVD diamond self-supporting film and then place it in a vacuum furnace for welding.

[0047] Further, 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.

[0048] Furthermore, in the above-mentioned CVD diamond self-supporting film cutting element preparation method, in step (7), the vacuum furnace adopts a programmed heating process, and the processing temperature is 700-900°C, wherein the welding heating time, final temperature and cooling time can be determined by experiments according to the composition of the solder to ensure the melting of the solder and the welding strength.

[0049] The third aspect of the present invention provides the above-mentioned CVD diamond self-supporting film cutting element for use as a cutting drill bit.

[0050] Furthermore, the CVD diamond self-supporting film cutting element can be used in the field of geological drilling under conditions such as oil drilling and deep drilling.

[0051] The CVD diamond self-supporting film cutting element provided by the present invention and its preparation method and application have one or more of the following beneficial effects:

[0052] (1) The present invention endows the CVD diamond self-supporting film cutting element with excellent overall wear resistance and high temperature resistance through the synergistic effect of the CVD diamond self-supporting film, the welding transition layer and the cemented carbide substrate.

[0053] (2) The CVD diamond self-supporting film in the upper layer of the cutting element provided by the present invention has a two-layer structure arranged in a specific sequence, that is, the MCD layer and the NCD layer are arranged alternately. Such an arrangement can ensure that when the diamond self-supporting film is subjected to external force, the crack extension is prevented and the crack deflection is induced. The interlayer slippage offsets part of the external force, thereby significantly improving the mechanical properties of the CVD diamond self-supporting film.

[0054] (3) The CVD diamond self-supporting film with alternating arrangement of MCD and NCD provided by the present invention can effectively block the formation of a columnar crystal structure with thin bottom and thick top due to the preferential rapid and long-term deposition of crystals in a certain direction in the traditional CVD diamond self-supporting film deposition process, thereby avoiding the situation where the columnar crystal structure seriously affects the mechanical properties of CVD diamond.

[0055] (4) In the method for preparing the CVD diamond self-supporting film of the present invention, the MCD layer prepared by step (1) ensures the hardness and wear resistance of the CVD diamond, and the NCD layer prepared by step (3) improves the toughness of the CVD diamond. Through the interaction between the MCD layer and the NCD layer, the technical problem in the prior art that diamond as a superhard material cannot take both toughness and hardness into account is overcome, and the wear ratio of the CVD diamond self-supporting film is significantly improved. The wear ratio of the CVD diamond self-supporting film provided by the present invention is 50% higher than that of the conventional CVD diamond self-supporting film.

[0056] (5) In the CVD diamond self-supporting film preparation method provided by the present invention, the transition section between step (2) and step (4) ensures a smooth transition of the condition parameters in the CVD diamond deposition furnace, thereby ensuring the quality and deposition time of the CVD diamond self-supporting film, and achieving a self-supporting film thickness of the millimeter level.

[0057] (6) The CVD diamond film provided by the present invention is composed entirely of C elements and does not contain any binder or catalyst, which can effectively avoid the problem of thermal damage.

[0058] (7) In the present invention, by adopting an appropriate flux and welding process, an effective connection between the CVD diamond self-supporting film and the cemented carbide is achieved, and the connection strength meets the use requirements, making it possible to use the CVD diamond self-supporting film as a cutting surface for geological exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a schematic diagram of the structure of the CVD diamond self-supporting film cutting element of the present invention;

[0060] Figure 2 This is the heavy-load wet grinding condition of the CVD diamond self-supporting film cutting element in Example 1 of the present invention;

[0061] Figure 3 This is a scanning electron microscope image of a cross section of a CVD diamond self-supporting film in Example 1 of the present invention;

[0062] Figure 4 This is a scanning electron microscope image of the MCD layer of the CVD diamond self-supporting film of Example 1 of the present invention;

[0063] Figure 5 This is a Raman spectrum of the CVD diamond self-supporting film MCD layer in Example 1 of the present invention;

[0064] Figure 6 This is a Raman spectrum diagram of the CVD diamond self-supporting film NCD layer in Example 1 of the present invention. DETAILED DESCRIPTION

[0065] The method of the present invention is further described in detail below by way of examples. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples.

[0066] 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 conventionally understood by those skilled in the art. In the event of a conflict, the definitions in this specification shall prevail.

[0067] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0068] Unless otherwise expressly indicated, throughout the specification and claims, the term "comprise" or its variations such as "include" or "comprising" etc. will 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) are to be understood as being modified in all cases by the term "about", regardless of whether "about" actually appears before the numerical value.

[0069] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight and pressure is gauge pressure.

[0070] In the context of this specification, any two or more embodiments of the present invention may be arbitrarily combined, and the technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0071] In the following examples and comparative examples, if no specific conditions are specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, if no manufacturer is specified, are all conventional products that can be obtained through commercial channels.

[0072] The scanning electron microscope images of the present invention were obtained using Zeiss EVO MA 15;

[0073] The Raman spectra of the present invention adopt LabRAM HR Evolution;

[0074] The mechanical properties of the CVD diamond self-supporting film using the wear ratio reaction in the present invention are tested according to the test method of JB / T-3235-1999.

[0075] Example 1

[0076] (1) The first deposition process is set as follows: methane gas at a flow rate of 30 sccm and hydrogen gas at a flow rate of 1000 sccm are respectively introduced into the CVD diamond deposition furnace, and the parameters of the CVD diamond deposition furnace are set as follows: the deposition furnace pressure is 3500 Pa, the single filament power is 0.9 kW, the filament temperature is 2350°C, the substrate temperature is 850°C, the distance between the filament and the substrate is 6 mm, and the first growth operation time is 300 min.

[0077] (2) The first transition time is set to 30 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the first deposition process to the second deposition process within the first transition time.

[0078] (3) The second deposition process is set as follows: methane gas at 2 sccm, hydrogen at 47 sccm, and argon at 900 sccm are introduced into the CVD diamond deposition furnace respectively; the CVD diamond deposition furnace parameters are set as follows: the deposition furnace pressure is 8000 Pa, the single filament power is 0.45 kW, the filament temperature is 2300°C, the substrate temperature is 750°C, the distance between the filament and the substrate is 8 mm, and the second growth operation time is 240 min.

[0079] (4) The second transition time is set to 30 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the second deposition process to the first deposition process within the second transition time.

[0080] (5) Repeat steps (1) to (4) for 80 cycles to obtain the CVD diamond self-supporting film.

[0081] (6) The diamond self-supporting film is double-sided ground and polished, and cut into a shape that matches the cemented carbide substrate.

[0082] (7) Prepare welding transition layer raw materials, and fully mix 15% wt. of diamond powder (0.1 μm), 10% wt. of tungsten carbide powder (1 μm) and 75% wt. of binder according to the mass ratio, wherein the binder is composed of silver (30% wt.), titanium (20% wt.), cobalt (35% wt.) and copper (15% wt.).

[0083] (8) The welding transition layer raw material is evenly applied to the diamond core surface and the cemented carbide substrate surface, and a pressure load is applied from top to bottom and placed in a vacuum brazing furnace. The vacuum degree of the vacuum brazing furnace is controlled to be 0.001 Pa, and the temperature is increased from room temperature to 850°C at 1°C / min, maintained at a constant temperature for 10 minutes, and cooled with the furnace.

[0084] Example 2

[0085] (1) The first deposition process is set as follows: methane gas at a flow rate of 40 sccm and hydrogen gas at a flow rate of 1000 sccm are respectively introduced into the CVD diamond deposition furnace, and the parameters of the CVD diamond deposition furnace are set as follows: the deposition furnace pressure is 4000 Pa, the single filament power is 0.85 kW, the filament temperature is 2200°C, the substrate temperature is 800°C, the distance between the filament and the substrate is 8 mm, and the first growth operation time is 240 min.

[0086] (2) The first transition time is set to 20 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the first deposition process to the second deposition process within the first transition time.

[0087] (3) Setting the second deposition process as follows: introducing methane gas at 10 sccm, hydrogen at 100 sccm, and argon at 900 sccm into the CVD diamond deposition furnace respectively; setting the CVD diamond deposition furnace parameters as follows: deposition furnace pressure of 9000 Pa, single filament power of 0.5 kW, filament temperature of 2350°C, substrate temperature of 800°C, distance between filament and substrate of 7 mm; and running the second growth process for 300 min.

[0088] (4) The second transition time is set to 20 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the second deposition process to the first deposition process within the second transition time.

[0089] (5) Repeat steps (1) to (4) for 100 times to obtain the CVD diamond self-supporting film.

[0090] (6) The diamond self-supporting film is double-sided ground and polished, and cut into a shape that matches the cemented carbide substrate.

[0091] (7) Prepare the welding transition layer raw materials, and fully mix 20% wt. of diamond powder (1 μm), 15% wt. of tungsten carbide powder (5 μm) and 65% wt. of binder according to the mass ratio, wherein the binder is composed of silver (25% wt.), titanium (15% wt.), cobalt (40% wt.) and copper (20% wt.).

[0092] (8) The welding transition layer raw material is evenly applied to the diamond core surface and the cemented carbide substrate surface, and a pressure load is applied from top to bottom and placed in a vacuum brazing furnace. The vacuum degree of the vacuum brazing furnace is controlled to be 0.005 Pa, and the temperature is increased from room temperature to 900 °C at 2 °C / min, maintained at a constant temperature for 10 min, and cooled with the furnace.

[0093] Example 3

[0094] (1) The first deposition process is set as follows: methane gas at a flow rate of 30 sccm and hydrogen gas at a flow rate of 1500 sccm are respectively introduced into the CVD diamond deposition furnace, and the parameters of the CVD diamond deposition furnace are set as follows: the deposition furnace pressure is 5000 Pa, the single filament power is 1.0 kW, the filament temperature is 2650°C, the substrate temperature is 1050°C, the distance between the filament and the substrate is 4 mm, and the first growth operation time is 600 min.

[0095] (2) The first transition time is set to 30 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the first deposition process to the second deposition process within the first transition time.

[0096] (3) The second deposition process is set as follows: methane gas at 2 sccm, hydrogen at 47 sccm, and argon at 900 sccm are introduced into the CVD diamond deposition furnace respectively; the CVD diamond deposition furnace parameters are set as follows: the deposition furnace pressure is 8000 Pa, the single filament power is 0.45 kW, the filament temperature is 2300°C, the substrate temperature is 750°C, the distance between the filament and the substrate is 8 mm, and the second growth operation time is 240 min.

[0097] (4) The second transition time is set to 30 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the second deposition process to the first deposition process within the second transition time.

[0098] (5) Repeat steps (1) to (4) 40 times to obtain the CVD diamond self-supporting film.

[0099] (6) The diamond self-supporting film is double-sided ground and polished, and cut into a shape that matches the cemented carbide substrate.

[0100] (7) Prepare the welding transition layer raw materials, and fully mix 18% wt. of diamond powder (10 μm), 13% wt. of tungsten carbide powder (10 μm) and 69% wt. of binder according to the mass ratio, wherein the binder is composed of silver (45% wt.), titanium (15% wt.), cobalt (30% wt.) and copper (10% wt.).

[0101] (8) The welding transition layer raw material is evenly applied to the diamond core surface and the cemented carbide substrate surface, and a pressure load is applied from top to bottom and placed in a vacuum brazing furnace. The vacuum degree of the vacuum brazing furnace is controlled to be 0.01 Pa, and the temperature is increased from room temperature to 700 °C at 1 °C / min, maintained at a constant temperature for 10 min, and cooled with the furnace.

[0102] Example 4

[0103] (1) The first deposition process is set as follows: methane gas at a flow rate of 30 sccm and hydrogen gas at a flow rate of 1000 sccm are respectively introduced into the CVD diamond deposition furnace, and the parameters of the CVD diamond deposition furnace are set as follows: the deposition furnace pressure is 3500 Pa, the single filament power is 0.9 kW, the filament temperature is 2350°C, the substrate temperature is 850°C, the distance between the filament and the substrate is 6 mm, and the first growth operation time is 300 min.

[0104] (2) The first transition time is set to 30 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the first deposition process to the second deposition process within the first transition time.

[0105] (3) The second deposition process is set as follows: methane gas at 10 sccm, hydrogen at 100 sccm, and argon at 900 sccm are introduced into the CVD diamond deposition furnace respectively; the CVD diamond deposition furnace parameters are set as follows: the deposition furnace pressure is 9000 Pa, the single filament power is 0.5 kW, the filament temperature is 2350°C, the substrate temperature is 800°C, the distance between the filament and the substrate is 7 mm, and the second growth operation time is 120 min.

[0106] (4) The second transition time is set to 30 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the second deposition process to the first deposition process within the second transition time.

[0107] (5) Repeat steps (1) to (4) for 80 cycles to obtain the CVD diamond self-supporting film.

[0108] (6) The diamond self-supporting film is double-sided ground and polished, and cut into a shape that matches the cemented carbide substrate.

[0109] (7) Prepare the welding transition layer raw materials, and fully mix 18% wt. of diamond powder (10 μm), 13% wt. of tungsten carbide powder (10 μm) and 69% wt. of binder according to the mass ratio, wherein the binder is composed of silver (25% wt.), titanium (35% wt.), cobalt (30% wt.) and copper (10% wt.).

[0110] (8) The welding transition layer raw material is evenly applied to the diamond core surface and the cemented carbide substrate surface, and a pressure load is applied from top to bottom and placed in a vacuum brazing furnace. The vacuum degree of the vacuum brazing furnace is controlled to be 0.01 Pa, and the temperature is increased from room temperature to 800 °C at 1 °C / min, and the temperature is kept constant for 10 min, and then cooled with the furnace.

[0111] Example 5

[0112] (1) The first deposition process is set as follows: methane gas at a flow rate of 40 sccm and hydrogen gas at a flow rate of 1000 sccm are respectively introduced into the CVD diamond deposition furnace, and the parameters of the CVD diamond deposition furnace are set as follows: the deposition furnace pressure is 4000 Pa, the single filament power is 0.85 kW, the filament temperature is 2200°C, the substrate temperature is 800°C, the distance between the filament and the substrate is 8 mm, and the first growth operation time is 240 min.

[0113] (2) The first transition time is set to 60 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the first deposition process to the second deposition process within the first transition time.

[0114] (3) Setting the second deposition process as follows: introducing methane gas at 5 sccm, hydrogen at 500 sccm, and argon at 500 sccm into the CVD diamond deposition furnace respectively; setting the CVD diamond deposition furnace parameters as follows: deposition furnace pressure of 15000 Pa, single filament power of 0.3 kW, filament temperature of 2200°C, substrate temperature of 700°C, distance between filament and substrate of 4 mm; and running the second growth process for 300 min.

[0115] (4) The second transition time is set to 60 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the second deposition process to the first deposition process within the second transition time.

[0116] (5) Repeat steps (1) to (4) for 100 times to obtain the CVD diamond self-supporting film.

[0117] (6) The diamond self-supporting film is double-sided ground and polished, and cut into a shape that matches the cemented carbide substrate.

[0118] (7) Prepare the welding transition layer raw materials, and fully mix 18% wt. of diamond powder (10 μm), 13% wt. of tungsten carbide powder (10 μm) and 69% wt. of binder according to the mass ratio, wherein the binder is composed of silver (25% wt.), titanium (35% wt.), cobalt (30% wt.) and copper (10% wt.).

[0119] (8) The welding transition layer raw material is evenly applied to the diamond core surface and the cemented carbide substrate surface, and a pressure load is applied from top to bottom and placed in a vacuum brazing furnace. The vacuum degree of the vacuum brazing furnace is controlled to be 0.01 Pa, and the temperature is increased from room temperature to 800 °C at 1 °C / min, and the temperature is kept constant for 10 min, and then cooled with the furnace.

[0120] Comparative Example 1 (single-layer structure)

[0121] (1) Methane gas at a flow rate of 40 sccm and hydrogen gas at a flow rate of 1000 sccm were respectively introduced into a CVD diamond deposition furnace, and the parameters of the CVD diamond deposition furnace were set as follows: the deposition furnace pressure was 4000 Pa, the single filament power was 0.85 kW, the filament temperature was 2200° C., the substrate temperature was 800° C., the distance between the filament and the substrate was 8 mm, and the operating time was 24000 min, thereby obtaining a CVD diamond self-supporting film.

[0122] (2) The diamond self-supporting film is double-sided ground and polished, and cut into a shape that matches the cemented carbide substrate.

[0123] (3) Prepare the welding transition layer raw materials, and fully mix 20% wt. of diamond powder (1 μm), 15% wt. of tungsten carbide powder (5 μm) and 65% wt. of binder according to the mass ratio, wherein the binder is composed of silver (25% wt.), titanium (15% wt.), cobalt (40% wt.) and copper (20% wt.).

[0124] (4) The welding transition layer raw material is evenly applied to the diamond core surface and the cemented carbide substrate surface, and a pressure load is applied from top to bottom and placed in a vacuum brazing furnace. The vacuum degree of the vacuum brazing furnace is controlled to be 0.005 Pa, and the temperature is increased from room temperature to 900 °C at 2 °C / min, maintained at a constant temperature for 10 min, and cooled with the furnace.

[0125] Comparative Example 2 (without first transition duration)

[0126] (1) The first deposition process is set as follows: methane gas at a flow rate of 30 sccm and hydrogen gas at a flow rate of 1000 sccm are respectively introduced into the CVD diamond deposition furnace, and the parameters of the CVD diamond deposition furnace are set as follows: the deposition furnace pressure is 3500 Pa, the single filament power is 0.9 kW, the filament temperature is 2350°C, the substrate temperature is 850°C, the distance between the filament and the substrate is 6 mm, and the first growth operation time is 300 min.

[0127] (2) The second deposition process is set as follows: methane gas at 2 sccm, hydrogen at 47 sccm, and argon at 900 sccm are introduced into the CVD diamond deposition furnace respectively; the CVD diamond deposition furnace parameters are set as follows: the deposition furnace pressure is 8000 Pa, the single filament power is 0.45 kW, the filament temperature is 2300°C, the substrate temperature is 750°C, the distance between the filament and the substrate is 8 mm, and the second growth operation time is 240 min.

[0128] (3) The second transition time is set to 30 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the second deposition process to the first deposition process within the second transition time.

[0129] (4) Repeat steps (1) to (3) 80 times to obtain a CVD diamond self-supporting film.

[0130] (5) The diamond self-supporting film is double-sided ground and polished, and cut into a shape matching the cemented carbide substrate.

[0131] (6) Prepare the welding transition layer raw materials, and fully mix 15% wt. of diamond powder (0.1 μm), 10% wt. of tungsten carbide powder (1 μm) and 75% wt. of binder according to the mass ratio, wherein the binder is composed of silver (30% wt.), titanium (20% wt.), cobalt (35% wt.) and copper (15% wt.).

[0132] (7) The welding transition layer raw material is evenly applied to the diamond core surface and the cemented carbide substrate surface, and a pressure load is applied from top to bottom and placed in a vacuum brazing furnace. The vacuum degree of the vacuum brazing furnace is controlled to be 0.001 Pa, and the temperature is increased from room temperature to 850°C at 1°C / min, maintained at a constant temperature for 10 minutes, and cooled with the furnace.

[0133] Comparative Example 3 (No Second Transition Duration)

[0134] (1) The first deposition process is set as follows: methane gas at a flow rate of 40 sccm and hydrogen gas at a flow rate of 1000 sccm are respectively introduced into the CVD diamond deposition furnace, and the parameters of the CVD diamond deposition furnace are set as follows: the deposition furnace pressure is 4000 Pa, the single filament power is 0.85 kW, the filament temperature is 2200°C, the substrate temperature is 800°C, the distance between the filament and the substrate is 8 mm, and the first growth operation time is 240 min.

[0135] (2) The first transition time is set to 20 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the first deposition process to the second deposition process within the first transition time.

[0136] (3) Setting the second deposition process as follows: introducing methane gas at 10 sccm, hydrogen at 100 sccm, and argon at 900 sccm into the CVD diamond deposition furnace respectively; setting the CVD diamond deposition furnace parameters as follows: deposition furnace pressure of 9000 Pa, single filament power of 0.5 kW, filament temperature of 2350°C, substrate temperature of 800°C, distance between filament and substrate of 7 mm; and running the second growth process for 300 min.

[0137] (4) Adjusting various parameters from the second deposition process to the first deposition process.

[0138] (5) Repeat steps (1) to (4) for 100 times to obtain a CVD diamond self-supporting film.

[0139] (6) The diamond self-supporting film is double-sided ground and polished, and cut into a shape that matches the cemented carbide substrate.

[0140] (7) Prepare the welding transition layer raw materials, and fully mix 20% wt. of diamond powder (1 μm), 15% wt. of tungsten carbide powder (5 μm) and 65% wt. of binder according to the mass ratio, wherein the binder is composed of silver (25% wt.), titanium (15% wt.), cobalt (40% wt.) and copper (20% wt.).

[0141] (8) The welding transition layer raw material is evenly applied to the diamond core surface and the cemented carbide substrate surface, and a pressure load is applied from top to bottom and placed in a vacuum brazing furnace. The vacuum degree of the vacuum brazing furnace is controlled to be 0.005 Pa, and the temperature is increased from room temperature to 900 °C at 2 °C / min, maintained at a constant temperature for 10 min, and cooled with the furnace.

[0142] Comparative Example 4 (No Diamond Particles in Flux)

[0143] (1) The first deposition process is set as follows: methane gas at a flow rate of 30 sccm and hydrogen gas at a flow rate of 1000 sccm are respectively introduced into the CVD diamond deposition furnace, and the parameters of the CVD diamond deposition furnace are set as follows: the deposition furnace pressure is 3500 Pa, the single filament power is 0.9 kW, the filament temperature is 2350°C, the substrate temperature is 850°C, the distance between the filament and the substrate is 6 mm, and the first growth operation time is 300 min.

[0144] (2) The first transition time is set to 30 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the first deposition process to the second deposition process within the first transition time.

[0145] (3) The second deposition process is set as follows: methane gas at 2 sccm, hydrogen at 47 sccm, and argon at 900 sccm are introduced into the CVD diamond deposition furnace respectively; the CVD diamond deposition furnace parameters are set as follows: the deposition furnace pressure is 8000 Pa, the single filament power is 0.45 kW, the filament temperature is 2300°C, the substrate temperature is 750°C, the distance between the filament and the substrate is 8 mm, and the second growth operation time is 240 min.

[0146] (4) The second transition time is set to 30 minutes, and the parameters of the CVD diamond deposition furnace are controlled to change linearly from the second deposition process to the first deposition process within the second transition time.

[0147] (5) Repeat steps (1) to (4) for 80 cycles to obtain the CVD diamond self-supporting film.

[0148] (6) The diamond self-supporting film is double-sided ground and polished, and cut into a shape that matches the cemented carbide substrate.

[0149] (7) Prepare the welding transition layer raw materials, and fully mix 10% wt. of tungsten carbide powder (1 μm) and 90% wt. of binder according to the mass ratio, wherein the binder is composed of silver (30% wt.), titanium (20% wt.), cobalt (35% wt.), and copper (15% wt.).

[0150] (8) The welding transition layer raw material is evenly applied to the diamond core surface and the cemented carbide substrate surface, and a pressure load is applied from top to bottom and placed in a vacuum brazing furnace. The vacuum degree of the vacuum brazing furnace is controlled to be 0.001 Pa, and the temperature is increased from room temperature to 850°C at 1°C / min, maintained at a constant temperature for 10 minutes, and cooled with the furnace.

[0151] Evaluation test:

[0152] The CVD diamond self-supporting films obtained in Examples 1-5 and Comparative Examples 1-4 were subjected to abrasion ratio tests. The abrasion ratio test conditions were as follows: the samples were uniformly laser cut to Double-sided grinding and polishing were performed. The core-forming surface was used as the working surface, the grinding wheel hardness was 3.7, the initial test speed was 25 m / s, and the rest of the test conditions and steps were carried out in accordance with JB / T-3235-1999.

[0153] The CVD diamond cutting elements obtained in Examples 1-5 and Comparative Examples 1-4 were subjected to a heavy-load wet grinding test. The heavy-load wet grinding test conditions were as follows: the complete cutting element was fixed on a fixture, the cutting surface was in contact with the natural granite, and a load of 1000N was applied between the two. The granite was controlled to rotate at 5 rpm, and running water was passed through the contact surface to cool it down. The product quality was measured by the grinding area of ​​the CVD diamond thick film when the granite was rotated 50 times.

[0154] Table 1 Test results of samples of embodiments and comparative examples

[0155]

[0156]

[0157] The above describes the specific implementation of the present invention in detail, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the various technical features being combined in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A CVD diamond self-supporting film cutting element, wherein: The CVD diamond self-supporting film cutting element comprises a CVD diamond self-supporting film, a welding transition layer and a cemented carbide substrate; the CVD diamond self-supporting film comprises an NCD layer and an MCD layer which are alternately arranged in sequence; the diamond grain size of the NCD layer is less than 1 μm, and the diamond grain size of the MCD layer is between 10 and 100 μm.

2. The CVD diamond self-supporting film cutting element according to claim 1, wherein: The thickness of the CVD diamond self-supporting film is not less than 1.0 mm, preferably 1.2 to 2.0 mm.

3. The CVD diamond self-supporting film cutting element according to claim 1, wherein: The MCD layer is a diamond polycrystalline structure, and the crystals of the polycrystalline structure are one or more of a cubic morphology, an octahedral morphology, a truncated octahedral morphology, and a faceted morphology, preferably an octahedral morphology; further, when it includes more than two crystal morphologies, it is a chaotic non-preferentially oriented crystal composed of more than two crystal morphologies.

4. The CVD diamond self-supporting film cutting element according to claim 1, wherein: The carbon in the MCD diamond layer is SP 3 Hybrid diamond phase is dominant, Raman spectroscopy characterization, SP 2 Characteristic peak intensity I of hybrid graphite phase crystal G and SP3 hybrid diamond phase characteristic peak intensity I D The ratio is I G / I D <0.3, preferably 1 G / I D <0.

25.

5. The CVD diamond self-supporting film cutting element according to claim 1, wherein: The NCD layer is a diamond polycrystalline structure, and the crystals of the polycrystalline structure are one or more of a cubic morphology, an octahedral morphology, a truncated octahedral morphology, and a faceted morphology. Further, when it includes more than two crystal morphologies, it is a chaotic crystal with no preferred orientation composed of more than two crystal morphologies; preferably, it is a chaotic crystal with no preferred orientation composed of more than two crystal morphologies.

6. The CVD diamond self-supporting film cutting element according to claim 1, wherein: There are obvious grain boundaries between the diamond crystals in the NCD layer. 2 Hybridized graphite phase filled with carbon atoms.

7. The CVD diamond self-supporting film cutting element according to claim 1, wherein: The carbon in the diamond of the NCD layer is SP 3 Hybrid diamond phase and SP 2 The hybrid graphite phase is uniformly mixed; in Raman spectroscopy characterization, SP 2 Characteristic peak intensity I of hybrid graphite phase crystal G and SP 3 Characteristic peak intensity of hybrid diamond phase I D The ratio is I G / I D Between 0.4 and 1.0, preferably between 0.5 and 0.8, and SP 3 The characteristic peaks of hybrid diamond phase are sharp.

8. The CVD diamond self-supporting film cutting element according to claim 1, wherein: The thickness of the MCD layer is 10-100 μm, and the thickness of the NCD layer is 1-20 μm.

9. The CVD diamond self-supporting film cutting element according to claim 1, wherein: The welding transition layer is an intermediate layer connecting the CVD diamond self-supporting film and the cemented carbide substrate. The welding transition layer includes diamond powder, tungsten carbide particles and a binder. Based on the total weight of the welding transition layer, the mass percentage of the diamond powder is 10% to 30%, preferably 15% to 20%; the mass percentage of the tungsten carbide particles is 5% to 25%, preferably 10% to 15%; the mass percentage of the binder is 45% to 85%, preferably 65% ​​to 75%.

10. The CVD diamond self-supporting film cutting element according to claim 9, wherein: The particle size of the diamond powder is 0.1-10 μm, and the particle size of the tungsten carbide particles is 1-10 μm.

11. The CVD diamond self-supporting film cutting element according to claim 9, wherein: The binder is a metal binder including silver, titanium, cobalt and copper. 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%.

12. The CVD diamond self-supporting film cutting element according to claim 1, wherein: The cemented carbide substrate is selected from tungsten-cobalt cemented carbide and / or tungsten-titanium-cobalt cemented carbide.

13. A method for preparing a CVD diamond self-supporting film cutting element, the method comprising the following steps: (1) depositing an MCD layer on a substrate by a first deposition process, wherein the first deposition process comprises respectively passing a first gas phase flow and a second gas phase flow into a CVD diamond deposition furnace, setting deposition parameters of the CVD diamond deposition furnace to first deposition process parameters, and running a first deposition time; (2) using a first transition process to perform transition processing on the deposition process in step (1), wherein the first transition process is to introduce a third gas phase flow, adjust the deposition parameters of the CVD diamond deposition furnace to the first transition process parameters, and run the first transition time; when the first transition time ends, the CVD diamond deposition furnace enters the second deposition process; (3) using a second deposition process to continue depositing the NCD layer on the MCD layer, the second deposition process is to respectively pass the first gas phase flow, the second gas phase flow and the third gas phase flow into the CVD diamond deposition furnace, set the deposition parameters of the CVD diamond deposition furnace to the second deposition process parameters, and run the second deposition time; (4) using a second transition process to perform transition processing on the deposition process in step (3), wherein the second transition process is to reduce or shut down the third gas phase flow, adjust the deposition parameters of the CVD diamond deposition furnace to the second transition process parameters, and run the second transition time; when the second transition time ends, the CVD diamond deposition furnace enters the first deposition process; (5) Repeat steps (1) to (4) until the thickness of the CVD diamond self-supporting film meets the requirements; (6) Mixing the welding transition layer raw materials in proportion and uniformly coating them on the growth surface of the CVD diamond self-supporting film and the surface of the cemented carbide substrate; (7) The growth surface of the CVD diamond self-supporting film is combined with the surface of the cemented carbide substrate, and then a pressure load is applied from top to bottom on the nucleation surface of the CVD diamond self-supporting film. The film is then placed in a vacuum furnace for welding to obtain a CVD diamond self-supporting film cutting element.

14. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: The first gas phase flow in step (1) is one or more of gaseous organic matter containing carbon elements and / or liquid organic matter containing carbon elements that is easily gasified, and the second gas phase flow in step (1) is hydrogen; the gaseous organic matter containing carbon elements is selected from one or more of methane, ethane, acetylene, propane, propylene, and propyne; the liquid organic matter containing carbon elements that is easily gasified is selected from one or more of methanol, ethanol, acetone, and petroleum ether.

15. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: The third gas phase flow in step (2) is argon.

16. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: The first deposition process parameters in step (1) are as follows: the deposition furnace pressure is 2000-5000 Pa, the single filament power is 0.8-1.2 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 first deposition process parameters are as follows: the deposition furnace pressure is 3000-4000 Pa, the single filament power is 0.85-0.95 kW, the single filament temperature is 2200-2600° C., and the substrate temperature is 800-950° C.

17. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: In step (1), the volume flow ratio of the first gas phase flow to the second gas phase flow is 1:50 to 1:20, preferably 3:100 to 1:

25.

18. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: The first deposition time in step (1) is 120 to 600 minutes, preferably 240 to 360 minutes.

19. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: The third gas phase flow in step (2) is argon.

20. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: In step (2), the first transition time is 10 to 60 minutes, preferably 20 to 40 minutes. In the first transition process, the deposition furnace pressure, the power of a single filament, and the volume flow rate of the gas phase flow linearly change to the parameters required by the second deposition process within the first transition time.

21. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: The second deposition process parameters in step (3) are: deposition furnace pressure 6000-15000 Pa, single filament power 0.3-0.7 kW, filament temperature 2200-2700° C., substrate temperature 700-1050° C., and the distance between the filament and the substrate is 4-8 mm; preferably, the deposition furnace pressure is 8000-13000 Pa, the single filament power is 0.45-0.6 kW, the single filament temperature is 2300-2600° C., and the substrate temperature is 750-850° C.

22. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: In step (3), the volume flow ratios of the first gas phase flow, the second gas phase flow and the third gas phase flow are as follows: first gas phase flow / (first gas phase flow+second gas phase flow)=0.01-0.3, preferably 0.04-0.2; third gas phase flow / (second gas phase flow+third gas phase flow)=0.5-1, preferably 0.9-1.

23. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: The second deposition time in step (3) is 120 to 1440 minutes, preferably 240 to 360 minutes.

24. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: The second transition time in step (4) is 10 to 60 minutes, preferably 20 to 40 minutes. The second transition process is that within the second transition time, the deposition furnace pressure, single filament power, and gas phase flow volume flow rate are linearly changed to the parameters required by the first deposition process.

25. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: In step (7), the pressure load applied from top to bottom on the CVD diamond self-supporting film nucleation surface is 0.1 to 1 MPa.

26. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: The vacuum degree of the vacuum furnace is set to 0.03Pa-0.001Pa, preferably 0.01Pa-0.001Pa.

27. The method for preparing a CVD diamond self-supporting film cutting element according to claim 13, wherein: In step (7), the vacuum furnace treatment temperature is 700-900°C.

28. The CVD diamond self-supporting film cutting element according to any one of claims 1 to 12 and / or the CVD diamond self-supporting film cutting element obtained by the preparation method according to any one of claims 13 to 27 is used as a cutting drill bit.

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