A cutting diamond compact and a method for manufacturing the same

Abstract

The application discloses a cutting diamond composite sheet and a preparation method thereof. The method comprises the following steps: first, a double-convex platform structure is processed on the surface of a cemented carbide substrate; then, a diamond preform is prepared according to the double-convex platform structure; and finally, a catalytic infiltration sheet is laid on the side of the diamond preform away from the cemented carbide substrate, and a high-temperature and high-pressure synthesis is performed on the sintering assembly, so that the composite forming process of the cutting diamond composite sheet is changed from the traditional direct sintering after simple material stacking to the preparation mode of presetting the front-end form, limiting the assembly relationship and connecting the subsequent composite forming, thereby improving the stability of the composite forming process, reducing the influence caused by the fluctuation of the front-end state and the incoordination of the sintering process, and making the obtained cutting diamond composite sheet have better process controllability and forming consistency in the preparation process.

Description

Technical Field

[0001] This application relates to the field of diamond technology for cutting, and in particular to a diamond composite sheet for cutting and its preparation method. Background Technology

[0002] Diamond composite sheets for cutting are typically formed by combining a superhard material portion with a cemented carbide support portion, and are widely used in rock cutting, drilling, and wear-resistant machining. These composite sheets withstand high loads and thermal effects during service. While current technology has enabled the fabrication of diamond composite sheets for cutting, challenges remain in the high-temperature, high-pressure composite forming process.

[0003] In the existing composite sheet fabrication process, the material state before sintering, the composite interface state, and the mass migration process during the high-temperature and high-pressure stage are coupled with each other. When there is a lack of effective coordination among these processes, the evolution rhythm of the composite system under high-temperature and high-pressure conditions is prone to inconsistency, which in turn makes the composite forming process itself exhibit strong volatility. This problem is not limited to a single process, but runs through the entire process of the composite sheet transforming from the unformed state to the final composite state.

[0004] Therefore, the existing diamond composite sheets for cutting suffer from insufficient stability in the composite forming process, making them susceptible to changes in the front-end state and sintering conditions. Improving the stability of the composite forming process during the fabrication of diamond composite sheets for cutting has become a pressing technical problem in this field. Summary of the Invention

[0005] The purpose of this application is to provide a diamond composite sheet for cutting and its preparation method, thereby solving the technical problem of insufficient stability in the composite forming process during the preparation of diamond composite sheets for cutting.

[0006] To achieve this objective, the present application adopts the following technical solution: A method for preparing a diamond composite sheet for cutting, comprising: A cemented carbide substrate is provided, and a double boss structure is machined on one side surface of the cemented carbide substrate; Diamond raw material and forming agent are mixed according to the double boss structure to obtain a diamond preform that matches the double boss structure; The diamond preform is assembled onto the cemented carbide matrix, and a catalytic melting sheet is laid on the side of the diamond preform away from the cemented carbide matrix to obtain the assembly to be sintered. The assembly to be sintered is subjected to high temperature and high pressure synthesis to obtain a diamond composite sheet for cutting.

[0007] Further, the step of providing a cemented carbide substrate and machining a double boss structure on one side surface of the cemented carbide substrate includes: A cemented carbide substrate blank is provided, and a first boss located in the middle and a second boss located on the outer periphery of the first boss are machined on one side surface of the cemented carbide substrate blank. The second boss is arranged in a ring shape, the height of the first boss is 0.2 to 1.0 mm, and the height of the second boss is 0.1 to 0.8 mm.

[0008] Further, the step of mixing diamond raw material with a forming agent according to the double-protrusion structure to obtain a diamond preform that mates with the double-protrusion structure includes: Select diamond raw materials, mix the diamond raw materials with a forming agent to obtain pre-formed powder; The pre-made powder is loaded into a mold and pressed to form a compact, wherein the forming surface of the mold is provided with a mating contour corresponding to the double boss structure. The pressed blank is subjected to a debonding treatment to obtain a diamond preform that matches the double boss structure. The debonding temperature is 350-550℃ and the holding time is 0.5-1 h.

[0009] Furthermore, the amount of the forming agent added is 0.5 to 3.0 wt% of the diamond raw material, and the forming agent includes at least one of paraffin wax, polyvinyl alcohol, polyvinyl butyral, and stearate.

[0010] Further, the step of assembling the diamond preform onto the cemented carbide substrate and laying a catalytic melting sheet on the side of the diamond preform facing away from the cemented carbide substrate includes: The cemented carbide substrate is placed at the assembly station, and the diamond preform is placed on the double boss structure of the cemented carbide substrate for pressing and positioning. The side of the diamond preform away from the cemented carbide matrix is ​​flattened, a catalytic melting sheet is laid on the flattened surface, and then pressed and positioned to obtain the assembly to be sintered.

[0011] Furthermore, the catalytic infiltration sheet includes at least one of cobalt-based metal sheet, nickel-based metal sheet, and cobalt-nickel alloy sheet, and the thickness of the catalytic infiltration sheet is 1 / 25 to 1 / 5 of the average thickness of the diamond preform.

[0012] Furthermore, the step of performing high-temperature and high-pressure synthesis on the assembly to be sintered includes: The assembly to be sintered is subjected to pre-compaction treatment, wherein the pressure of the pre-compaction treatment is 4.5 to 6.2 GPa and the temperature is 900 to 1200℃; The pre-compacted assembly to be sintered is pressurized to 5.2–7.0 GPa and heated to 1100–1450 °C to complete the melting and infiltration of the catalytic melting and infiltration sheet; The sintered assembly is subjected to densification sintering and cooling treatment to obtain a diamond composite sheet for cutting.

[0013] Furthermore, the steps of performing densification sintering treatment and cooling treatment on the assembly to be sintered after melt infiltration include: The assembly to be sintered after molten infiltration is pressurized to 6.2–7.8 GPa and heated to 1450–1630 °C for densification sintering. The assembly to be sintered after densification sintering is subjected to stabilization cooling and depressurization treatment to obtain a diamond composite sheet for cutting.

[0014] This application also discloses a diamond composite sheet for cutting, which is prepared by the method for preparing a diamond composite sheet for cutting as described in any of the above claims.

[0015] Compared with the prior art, this application has the following beneficial effects: The method for preparing the diamond composite sheet for cutting disclosed in this application involves first machining a double-protrusion structure on the surface of a cemented carbide substrate, then preparing a diamond preform that matches the double-protrusion structure, and finally laying a catalytic melting sheet on the side of the diamond preform away from the cemented carbide substrate. The assembly to be sintered is then subjected to high-temperature and high-pressure synthesis. This transforms the composite forming process of the diamond composite sheet for cutting from the traditional method of simply stacking materials and then directly sintering to a method that integrates pre-setting the front-end morphology, defining the assembly relationship, and connecting the subsequent composite forming. This allows for unified constraints on the material state before sintering, the composite interface state, and the evolution process under high-temperature and high-pressure conditions during the composite forming stage, improving the stability of the composite forming process and reducing the impact of fluctuations in the front-end state and incoordination in the sintering process. This results in a diamond composite sheet for cutting with better process controllability and forming consistency during preparation. Attached Figure Description

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

[0017] The structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the implementation conditions of this application. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0018] Figure 1 A schematic diagram of the overall steps in the preparation method of diamond composite sheets for cutting; Figure 2 This is a cross-sectional view of a diamond composite sheet used for cutting. Detailed Implementation

[0019] To make the inventive objectives, features, and advantages of this application more apparent and understandable, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] In the description of this application, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component centrally located at the same time.

[0021] The technical solution of this application will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] refer to Figure 1 This application provides a method for preparing a diamond composite sheet for cutting, comprising: S1: Provide a cemented carbide substrate, and machine a double boss structure on one side surface of the cemented carbide substrate; In step S1, a cemented carbide substrate blank is prefabricated according to the shape and specifications of the composite sheet. The substrate can be made of a conventional cobalt-containing cemented carbide material system. The substrate blank is first corrected at the end face, that is, one side is used as the positioning reference surface, and then the other side is finely finished to make the surface to be processed in a relatively regular initial state. After the reference is established, the geometric center is determined on the surface to be processed, and then the double boss machining trajectory is constructed with the geometric center as the starting point. During processing, the first boss in the center is processed first, and then the second boss located on its outer periphery is processed. The first boss is located in the middle of the composite side, corresponding to the central mating area of ​​the bottom of the prefabricated body; the second boss is arranged around the first boss, corresponding to the outer peripheral mating area of ​​the bottom of the prefabricated body. In actual processing, the double boss contour can be gradually formed by combining CNC turning, precision milling, and surface grinding with forming tool dressing. In terms of processing sequence, the general contour of the boss is first rough machined, and then the top surface height and circumferential boundary are corrected by finishing to ensure the coaxiality of the two bosses with respect to the center of the substrate. After forming the central boss and the annular boss, the edges of the bosses are chamfered or rounded to transform the contour from a sharp step to a gentler transition that is more suitable for fitting. The processed substrate is then cleaned, specifically by a combination of organic solvent cleaning, ultrasonic cleaning, and low-temperature drying, to remove residual oil, dust, and fine particles from machining, resulting in a cemented carbide substrate with a double-bore structure.

[0023] S2: The diamond raw material and the forming agent are mixed according to the double boss structure to obtain a diamond preform that matches the double boss structure; In step S2, the diamond raw material is screened and pretreated, preferably using diamond micron powder with a relatively concentrated particle size distribution. After selecting the diamond raw material, a forming agent is introduced. The function of the forming agent in this application is to improve the aggregation stability of the powder before pressing and to be removed after debinding. In practice, the diamond raw material is dry-mixed to make the powder loose and uniform. Then, the forming agent is added in powder form or in a dissolved / dispersed state, allowing it to gradually adhere to the surface of the diamond particles. For diamond raw materials with poor flowability or easy agglomeration, a wet mixing method can be used, that is, a small amount of volatile medium is introduced after the forming agent is added, so that the forming agent is first dispersed in the liquid phase and then comes into contact with the diamond particles. After mixing, the material is moderately dried to reduce the volatile components in the system to a level that is conducive to pressing. Otherwise, excessive liquid content may cause edge cracking or compact springback during pressing. After obtaining a stable pre-formed powder, it is molded. The forming surface of the mold should be designed in reverse according to the geometry of the double boss, that is, the bottom of the compact pressed by the mold has a bottom contour that matches the double boss. In practice, a central recess and an outer circumferential recess can be set on at least one side of the forming surface of the upper and lower molds, so that the pressed blank naturally forms a concave structure on the bottom surface corresponding to the double protrusions. During pressing, the pressure application process is controlled to be gradual loading, and after the blank is formed, a debonding process is performed. Debonding is achieved by controlled heating to gradually precipitate and remove the forming agent, while trying to maintain the overall morphology of the blank as much as possible to prevent significant collapse. In practice, the blank can be placed in a vacuum environment or an inert protective atmosphere, heated to the set temperature zone at a relatively slow heating rate and held at that temperature, so that the organic components are gradually discharged. After debonding is completed, a preform is obtained.

[0024] S3: Assemble the diamond preform onto the cemented carbide matrix, and lay a catalytic melting sheet on the side of the diamond preform away from the cemented carbide matrix to obtain the assembly to be sintered; In step S3, the double-bore cemented carbide substrate obtained in step S1 is placed in an assembly platform or special assembly fixture, with its composite side facing upwards and kept horizontal. The diamond preform obtained in step S2 is placed axially onto the composite side of the substrate, so that the bottom contour of the preform gradually contacts the contour of the double bore. Specifically, the center of the preform is first aligned with the center of the substrate, and then it is slowly lowered. After the bottom of the preform contacts the first bore, the outer periphery is gradually fitted with the second bore through circumferential fine adjustment to avoid assembly misalignment caused by one side falling first and the other side being suspended. After the preform is pressed into place, the upper surface of the preform is flattened or lightly shaped to form a relatively flat patch surface under low mechanical load. After surface finishing, the catalytic melting sheet is laid. The catalytic melting sheet is a metal supply component, and its laying direction corresponds to the contour of the upper surface of the preform. In practice, the melt-infiltrating sheet should be cut according to the effective area of ​​the precast surface, ensuring its shape is roughly consistent with the top contour of the precast. This avoids excessive expansion leading to metal overflow at high temperatures, and also prevents insufficient coverage due to excessive size. When laying the sheet, it should be applied flat from one end to the other to reduce air trapping between the sheet and the precast surface or the formation of localized curling edges. After laying, light pressure should be used for positioning, ensuring sufficient contact between the melt-infiltrating sheet and the precast surface. The substrate should be at the bottom, the precast in the middle conforming to the double-protrusion contour, and the catalytic melt-infiltrating sheet at the top, conforming to the precast surface.

[0025] S4: The assembly to be sintered is subjected to high temperature and high pressure synthesis to obtain a diamond composite sheet for cutting. In step S4, the assembly to be sintered is loaded into the corresponding pressure unit of the high-temperature and high-pressure equipment, entering the pre-compaction stage. The purpose of the pre-compaction stage is to allow the contact interfaces in the assembly to be compacted under relatively mild conditions. Therefore, it can be initially loaded into a medium pressure range and heated to a level below the final sintering temperature. In this stage, the contact between the double bosses and the bottom contour of the preform will be further stabilized, the original large pores inside the preform will be initially compressed, and the catalytic melting sheet and the surface of the preform will also fit more closely due to the pressure. After pre-compaction is completed, the temperature and pressure are increased to a higher range, causing the catalytic melting sheet to melt and penetrate downwards along the pores inside the preform. It is worth noting that in the above embodiment, an independent catalytic melting sheet is set above the preform, and the path of the molten metal is different from the existing method of metal penetration from the matrix upwards. In practice, the temperature is controlled to a range sufficient to melt the sheet but not yet to enter the final fully dense sintering zone, allowing the metal to flow and penetrate first. After the catalytic metal has completed its initial infiltration, the process proceeds to the final dense sintering stage. During this stage, pressure and temperature reach high levels, and the diamond particles in the preform gradually transition from a compacted contact state to a truly sintered bonded state. Simultaneously, a stable composite is formed between the preform and the cemented carbide matrix. After dense sintering, controlled cooling is performed to allow the formed diamond sintered body and matrix to undergo partial thermal shrinkage under high external pressure. Then, the pressure is gradually released back to a normal state, preventing interface instability caused by the combined effects of temperature drop and pressure release immediately after the sintered body is formed. After cooling and removal, a diamond composite sheet for cutting is obtained.

[0026] In one optional embodiment, referring to Table 1, comparative examples were selected for performance testing. All performance tests were conducted under uniform conditions. All samples used composite sheet structures with the same external dimensions. The material system of the cemented carbide matrix, cobalt content, matrix size, diamond raw material particle size range, forming agent addition ratio, preform pressing pressure, debinding process, total amount of catalyst metal, high-temperature and high-pressure equipment model, assembly method, heating and pressurization path, maximum sintering temperature, maximum sintering pressure, holding and pressurizing time, cooling and depressurization regime, and post-sintering finishing method were all kept consistent. Furthermore, each group of samples could be prepared and tested in parallel with 30 sheets to minimize the impact of single-batch fluctuations on the test results. Comparative Example 1 uses a direct assembly method of planar cemented carbide matrix and flat-bottomed diamond preform. Instead of setting an independent catalytic melting sheet on the side of the diamond preform away from the matrix, the catalysis and composite are mainly completed by the upward migration of the matrix side metal under high temperature and high pressure. Therefore, the initial bonding state of the interface before sintering is relatively ordinary, the positioning and constraint effect during the assembly process is weak, and it is difficult to maintain the coordination of the densification process in different regions during the composite process. The final composite forming qualification rate is 82.4%, the interfacial shear strength is 326 MPa, the residual strength retention rate after thermal stabilization is 74.8%, and the interlaminar cracking rate after sintering is 11.7%. Comparative Example 2 made some improvements to the substrate structure, which can be understood as using a single-protrusion substrate and a corresponding single-concave prefabricated body for assembly. Compared with the completely planar structure, it has improved the positioning and local contact state of the central area. However, its ability to support, constrain and adjust the fit of the outer peripheral area is still weaker than the double-protrusion mating structure of this embodiment. At the same time, its coordination of catalytic metal infiltration and interface evolution is not as good as this embodiment. Therefore, its comprehensive performance is between Comparative Example 1 and this embodiment, with a composite forming qualification rate of 88.1%, an interfacial shear strength of 357 MPa, a residual strength retention rate of 81.6% after thermal stabilization, and an interlayer cracking rate of 7.9% after sintering. This embodiment employs a double-protrusion cemented carbide substrate, with the bottom of the diamond preform forming a matching profile to the double protrusions. Simultaneously, a catalytic melting sheet is laid on the side of the diamond preform facing away from the cemented carbide substrate. This allows the assembly to form a clearer center-periphery partitioned support relationship before sintering, making the interface contact more stable during the pre-compaction stage. Upon entering the high-temperature and high-pressure stage, the catalytic metal can participate more effectively in the infiltration of the preform's internal pores and the subsequent densification process, thereby improving the coordination and stability of the composite forming process. Therefore, this embodiment achieves a 92.6% composite forming pass rate, an interfacial shear strength of 381 MPa, a residual strength retention rate after thermal stabilization of 87.3%, and an interlaminar cracking rate of 3.8% after sintering. As can be seen from the data in the table, although the improvement in this embodiment compared to the two comparative examples is not excessively large, it exhibits a relatively stable and continuous improvement trend.

[0027] Table 1: In one embodiment, the step of providing a cemented carbide substrate and machining a double boss structure on one side surface of the cemented carbide substrate includes: A cemented carbide substrate blank is provided, and a first boss located in the middle and a second boss located on the outer periphery of the first boss are machined on one side surface of the cemented carbide substrate blank. The second boss is arranged in a ring shape, the height of the first boss is 0.2 to 1.0 mm, and the height of the second boss is 0.1 to 0.8 mm.

[0028] In the above embodiments, a circular cemented carbide substrate blank is provided. The substrate is pre-set according to the final product specifications, for example, the blank size corresponding to the outer diameter of a conventionally machined composite sheet can be used, and a subsequent finishing allowance is reserved in the thickness direction of the blank. A double boss structure is machined on one side surface of the cemented carbide substrate blank, wherein a first boss is machined in the middle, and a second boss is machined around the outer periphery of the first boss. The second bosses are distributed in a ring. The height of the first boss is set to 0.2-1.0 mm, and the height of the second boss is set to 0.1-0.8 mm. The two ranges are set because when the first boss is less than 0.2 mm, the central contour feature is too weak, and the central positioning is not obvious after the preform is pressed together; when it is greater than 1.0 mm, it is easy to form an excessively thin structure in the corresponding area of ​​the central part of the preform. If the second boss is less than 0.1 mm, the outer ring support effect is insufficient; if it is greater than 0.8 mm, it is easy to cause premature contact of the outer periphery and forward shift of local force. During the actual machining process, a reference can be established first by leveling the end face, and then the central boss can be formed by CNC turning or precision grinding. After that, the outer annular boss can be machined in a coaxial manner. After machining, check whether the height difference between the top surface of the first boss and the top surface of the second boss falls within the preset range, and check the coaxiality of the two relative to the center of the base.

[0029] In one embodiment, the step of mixing diamond raw material with a forming agent according to the double-bore structure to obtain a diamond preform that mates with the double-bore structure includes: Select diamond raw materials, mix the diamond raw materials with a forming agent to obtain pre-formed powder; The pre-made powder is loaded into a mold and pressed to form a compact, wherein the forming surface of the mold is provided with a mating contour corresponding to the double boss structure. The pressed blank is subjected to a debonding treatment to obtain a diamond preform that matches the double boss structure. The debonding temperature is 350-550℃ and the holding time is 0.5-1 h.

[0030] In the above embodiments, diamond raw materials are first selected, preferably diamond micro powder with a narrow particle size distribution, to reduce the unevenness of local accumulation after mixing. The diamond raw materials are mixed with a forming agent to obtain a pre-formed powder. During mixing, a low-speed premixing is initially used to ensure the forming agent is evenly distributed among the diamond particles. The mixing time is then adjusted based on the powder's state to ensure the edges of the pressed compact remain intact. After obtaining the pre-formed powder, it is placed into a mold for pressing. The mold has a mating contour corresponding to the double-protrusion structure on its forming surface; that is, the mold forming surface pre-carries a reverse geometric structure corresponding to the first and second protrusions, resulting in a mating contour on the bottom surface of the pressed compact. After the compact is formed, a debinding process is performed. The debinding temperature is set at 350–550°C, and the holding time is set at 0.5–1 hour. During implementation, the temperature can be slowly raised to the target temperature under vacuum or a protective atmosphere, and then held for a predetermined time to allow the forming agent to gradually escape. After debonding, the original compact is transformed into a diamond preform with a certain self-supporting strength and maintaining the bottom fit profile.

[0031] In one embodiment, the amount of the forming agent added is 0.5 to 3.0 wt% of the diamond raw material, and the forming agent includes at least one of paraffin wax, polyvinyl alcohol, polyvinyl butyral, and stearate.

[0032] In this embodiment, the range of forming agent addition is related to the flow state of the preform powder, the integrity of the compact forming, and the retention of pore structure after debinding. When the amount of forming agent added is less than 0.5 wt%, the cohesion of the preform powder formed after mixing the diamond raw material is low, which easily leads to edge powder shedding, demolding edge breakage, or insufficient compact strength during pressing. When the amount added is greater than 3.0 wt%, the proportion of organic components inside the compact will be too high, increasing the subsequent debinding burden and potentially causing overfilling of the original pores inside the preform, which is not conducive to the subsequent entry of catalytic metals. Regarding the type of forming agent, paraffin wax is suitable for imparting good plasticity and pressing lubricity to the powder, polyvinyl alcohol is beneficial for improving the uniformity after wet dispersion, polyvinyl butyral can improve the toughness and edge integrity of the compact, and stearates are often used to improve powder flowability and demolding state. In specific implementations, individual or combined selections can be made according to the particle size of the diamond raw material, the mixing method, and the complexity of the compact shape. For example, for diamond raw materials with fine particle size and relatively insufficient flowability, paraffin wax and stearate can be compounded; for systems using wet mixing processes, polyvinyl alcohol or polyvinyl butyral can be used as the main forming agent.

[0033] In one embodiment, the step of assembling the diamond preform onto the cemented carbide substrate and laying a catalytic melting sheet on the side of the diamond preform opposite to the cemented carbide substrate includes: The cemented carbide substrate is placed at the assembly station, and the diamond preform is placed on the double boss structure of the cemented carbide substrate for pressing and positioning. The side of the diamond preform away from the cemented carbide matrix is ​​flattened, a catalytic melting sheet is laid on the flattened surface, and then pressed and positioned to obtain the assembly to be sintered.

[0034] In this embodiment, a pre-fabricated cemented carbide substrate with a double-protrusion structure is placed at the assembly station. Using a fixture or positioning table, its composite side is kept facing upwards. The diamond preform is placed on the double-protrusion structure and positioned by light pressure, ensuring the bottom contour of the preform aligns with the contour of the double protrusions. The side of the diamond preform facing away from the cemented carbide substrate is flattened. This can be achieved by applying short, light pressure to the upper surface of the preform using a flat-headed pressure block, resulting in a relatively flat surface. After flattening, a catalytic melting sheet is laid on this surface and positioned by pressing. This pressing ensures a stable fit of the melting sheet on the preform surface, reducing warping or displacement during subsequent heating. When laying the sheet, a sheet size similar to the contour of the upper surface of the preform can be used to avoid excessively large sheets extending outwards or insufficient coverage due to excessively small sheets. After completing the above steps, the assembly to be sintered is obtained.

[0035] In one embodiment, the catalytic infiltration sheet includes at least one of a cobalt-based metal sheet, a nickel-based metal sheet, and a cobalt-nickel alloy sheet, and the thickness of the catalytic infiltration sheet is 1 / 25 to 1 / 5 of the average thickness of the diamond preform.

[0036] In this embodiment, the catalytic infiltration sheet is a thin metal sheet. Cobalt-based metal sheets, nickel-based metal sheets, and cobalt-nickel alloy sheets are all capable of forming a relatively stable molten metal phase under subsequent high temperature and high pressure conditions, and infiltrating downwards along the original pores inside the diamond preform. The thickness of the catalytic infiltration sheet is 1 / 25 to 1 / 5 of the average thickness of the diamond preform. For example, when the average thickness of the diamond preform is 1.0 mm, the thickness of the catalytic infiltration sheet can be set to 0.04 to 0.20 mm; when the average thickness of the diamond preform is 1.5 mm, the thickness of the catalytic infiltration sheet can be set to 0.06 to 0.30 mm. If the sheet thickness is lower than the above lower limit, the amount of metal available for infiltration during the high temperature and high pressure process is insufficient, easily leading to insufficient infiltration in the upper part of the preform; if the sheet thickness exceeds the above upper limit, the total metal content of the sheet is too high, making it easier to form an enriched layer in local areas after subsequent melting.

[0037] In one embodiment, the step of performing high-temperature and high-pressure synthesis on the assembly to be sintered includes: The assembly to be sintered is subjected to pre-compaction treatment, wherein the pressure of the pre-compaction treatment is 4.5 to 6.2 GPa and the temperature is 900 to 1200℃; The pre-compacted assembly to be sintered is pressurized to 5.2–7.0 GPa and heated to 1100–1450 °C to complete the melting and infiltration of the catalytic melting and infiltration sheet; The sintered assembly is subjected to densification sintering and cooling treatment to obtain a diamond composite sheet for cutting.

[0038] In this embodiment, the assembly to be sintered is placed into the pressure-bearing component of a high-temperature, high-pressure equipment for pre-compaction. The pressurization is performed in stages: first, atmospheric pressure is increased to 2.0–3.0 GPa as the initial compaction stage, allowing the contact interfaces within the assembly to reach a stable contact state; then, the pressure is increased further to 4.5–6.2 GPa as the pre-compaction pressure. The external pressure is increased segment by segment according to the equipment's loading curve, with brief pauses after each pressure increase to reduce sudden stress changes within the assembly. Simultaneously with the pressurization, the temperature is raised to 600–800°C to achieve temperature uniformity across the assembly, and then further increased to 900–1200°C and maintained. During the pre-compaction stage, both pressure and temperature increase incrementally into the target range. After the assembly reaches a pre-compacted state at 4.5–6.2 GPa and 900–1200°C, the pressure is further increased to 5.2–7.0 GPa, and the temperature is gradually increased from the previous stage to 1100–1450°C. This gradual increase involves first raising the temperature from the pre-compacted endpoint to the zone where the metal sheet begins to soften, and then raising it to the zone where the sheet is fully molten and infiltrated, while simultaneously increasing the pressure to the external pressure level required for metal infiltration. During this process, the softening of the metal sheet is first observed or controlled according to a preset time window, then it is allowed to enter a molten state, and a certain time is maintained to allow the molten metal to infiltrate into the diamond preform. Since the catalytic infiltration sheet is located above the preform, this embodiment mainly aims to complete the transformation from sheet metal to molten metal, and the infiltration process from the upper surface to the interior. After this process is completed, the assembly to be sintered can proceed to the subsequent densification sintering treatment.

[0039] In one embodiment, the steps of densifying and cooling the sintered assembly after melt infiltration include: The assembly to be sintered after molten infiltration is pressurized to 6.2–7.8 GPa and heated to 1450–1630 °C for densification sintering. The assembly to be sintered after densification sintering is subjected to stabilization cooling and depressurization treatment to obtain a diamond composite sheet for cutting.

[0040] In this embodiment, after the melting and infiltration of the catalytic infiltration sheet in the previous stage is completed, the assembly to be sintered is further pushed into the dense sintering stage, with the pressure and temperature increases also carried out gradually. Specifically, the pressure can be increased from the previous stage's 5.2–7.0 GPa range to 6.2–7.8 GPa, and the temperature can be gradually increased from 1100–1450℃ to 1450–1630℃. During the pressure increase, a method of rapidly approaching the target lower limit and then slowly approaching the target set value can be adopted to reduce the risk of local instability within the assembly at the end of the high pressure stage. During the temperature increase, the assembly can first pass through an intermediate transition temperature zone before entering the final sintering temperature zone of 1450–1630℃. After entering the final sintering temperature zone, the assembly is maintained at this temperature and pressure conditions for a certain period of time to allow the diamond preform to transition from the previous molten infiltration state to a truly dense sintered state. After dense sintering, a stabilization cooling process is first performed to allow the assembly to drop from the final sintering temperature range to a lower temperature range. Pressure is then released after the temperature has decreased. Specifically, the temperature can be gradually reduced from 1450–1630°C according to a set cooling rate, while maintaining the assembly under pressure. This allows the sintered composite to transition from a high temperature to a medium temperature, and finally return to normal pressure. Once both temperature and pressure have returned to normal conditions, the composite can be removed.

[0041] It is worth noting that all the devices described in this application can be implemented using existing technology. refer to Figure 2 The present invention also discloses a diamond composite sheet for cutting, which is prepared by the method for preparing a diamond composite sheet for cutting as described in any of the above claims.

[0042] In this embodiment, the diamond composite sheet for cutting includes a second boss, a first boss, and a cemented carbide substrate. The cemented carbide substrate constitutes the lower main support portion of the composite sheet, and the first and second bosses are formed on the upper surface of the cemented carbide substrate. Specifically, the first boss is located in the central region of the upper surface of the cemented carbide substrate, and the second boss is located in the outer peripheral region of the first boss, with the second bosses arranged in a ring shape along the circumference. The height of the first boss can be set to 0.2–1.0 mm, and the height of the second boss can be set to 0.1–0.8 mm. The first boss is higher than the second boss, forming a higher central interface portion on the cross-section of the composite sheet, and the second boss forming a ring-shaped, slightly higher interface portion on its outer periphery.

[0043] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a diamond composite sheet for cutting, characterized in that, include: A cemented carbide substrate is provided, and a double boss structure is machined on one side surface of the cemented carbide substrate; Diamond raw material and forming agent are mixed according to the double boss structure to obtain a diamond preform that matches the double boss structure; The diamond preform is assembled onto the cemented carbide matrix, and a catalytic melting sheet is laid on the side of the diamond preform away from the cemented carbide matrix to obtain the assembly to be sintered. The assembly to be sintered is subjected to high temperature and high pressure synthesis to obtain a diamond composite sheet for cutting.

2. The method for preparing a diamond composite sheet for cutting according to claim 1, characterized in that, The step of providing a cemented carbide substrate and machining a double boss structure on one side surface of the cemented carbide substrate includes: A cemented carbide substrate blank is provided, and a first boss located in the middle and a second boss located on the outer periphery of the first boss are machined on one side surface of the cemented carbide substrate blank. The second boss is arranged in a ring shape, the height of the first boss is 0.2 to 1.0 mm, and the height of the second boss is 0.1 to 0.8 mm.

3. The method for preparing a diamond composite sheet for cutting according to claim 2, characterized in that, The step of mixing diamond raw material with a forming agent according to the double-convex structure to obtain a diamond preform that mates with the double-convex structure includes: Select diamond raw materials, mix the diamond raw materials with a forming agent to obtain pre-formed powder; The pre-made powder is loaded into a mold and pressed to form a compact, wherein the forming surface of the mold is provided with a mating contour corresponding to the double boss structure. The pressed blank is subjected to a debonding treatment to obtain a diamond preform that matches the double boss structure. The debonding temperature is 350-550℃ and the holding time is 0.5-1 h.

4. The method for preparing a diamond composite sheet for cutting according to claim 1, characterized in that, The amount of the forming agent added is 0.5 to 3.0 wt% of the diamond raw material, and the forming agent includes at least one of paraffin wax, polyvinyl alcohol, polyvinyl butyral, and stearate.

5. The method for preparing a diamond composite sheet for cutting according to claim 1, characterized in that, The step of assembling the diamond preform onto the cemented carbide substrate and laying a catalytic melting sheet on the side of the diamond preform opposite to the cemented carbide substrate includes: The cemented carbide substrate is placed at the assembly station, and the diamond preform is placed on the double boss structure of the cemented carbide substrate for pressing and positioning. The side of the diamond preform away from the cemented carbide matrix is ​​flattened, a catalytic melting sheet is laid on the flattened surface, and then pressed and positioned to obtain the assembly to be sintered.

6. The method for preparing a diamond composite sheet for cutting according to claim 1, characterized in that, The catalytic melting sheet includes at least one of cobalt-based metal sheet, nickel-based metal sheet, and cobalt-nickel alloy sheet, and the thickness of the catalytic melting sheet is 1 / 25 to 1 / 5 of the average thickness of the diamond preform.

7. The method for preparing a diamond composite sheet for cutting according to claim 1, characterized in that, The step of performing high-temperature and high-pressure synthesis on the assembly to be sintered includes: The assembly to be sintered is subjected to pre-compaction treatment, wherein the pressure of the pre-compaction treatment is 4.5 to 6.2 GPa and the temperature is 900 to 1200℃; The pre-compacted assembly to be sintered is pressurized to 5.2–7.0 GPa and heated to 1100–1450 °C to complete the melting and infiltration of the catalytic melting and infiltration sheet; The sintered assembly is subjected to densification sintering and cooling treatment to obtain a diamond composite sheet for cutting.

8. The method for preparing a diamond composite sheet for cutting according to claim 7, characterized in that, The steps of densifying and sintering the assembly to be sintered after melt infiltration, and then cooling it, include: The assembly to be sintered after molten infiltration is pressurized to 6.2–7.8 GPa and heated to 1450–1630 °C for densification sintering. The assembly to be sintered after densification sintering is subjected to stabilization cooling and depressurization treatment to obtain a diamond composite sheet for cutting.

9. A diamond composite sheet for cutting, characterized in that, It is prepared by the method for preparing diamond composite sheets for cutting as described in any one of claims 1 to 8.

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