A method for preparing a complex interface polycrystalline diamond compact based on powder extrusion printing

Abstract

The present application relates to a kind of complex interface polycrystalline diamond compact preparation method based on powder extrusion printing forming;Belong to PDC design preparation technical field.Its preparation method includes: preparing diamond feed and hard alloy feed respectively;Then according to target three-dimensional structure modeling, three-dimensional structure is converted into the multiple layer two-dimensional structure graph that printing equipment can identify by slice software;Then through multiple extrusion head, diamond-hard alloy composite green body of set structure is obtained by printing;Finally, finished product is obtained after defatting, pre-sintering, high temperature and high pressure sintering.The present application realizes diamond and hard alloy double material heterostructure integrated forming, and provides a new method for the development and preparation of high-performance complex interface structure PDC product.The present application is simple and controllable, and the performance of the obtained product is excellent, which is convenient for industrial application.

Description

Technical Field

[0001] This invention relates to a method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing; it belongs to the field of PDC design and fabrication technology. Background Technology

[0002] Polycrystalline diamond cemented carbide (PDC), a composite sintered body obtained by high-temperature and high-pressure processing of diamond and cemented carbide, possesses both the high hardness and wear resistance of polycrystalline diamond and the high toughness, low elastic modulus, and good impact resistance of cemented carbide. Traditional PDC is produced using diamond powder and a commercially available cemented carbide matrix as raw materials. The diamond powder is placed on the cemented carbide matrix and compacted, followed by high-temperature and high-pressure sintering and post-processing methods such as coarse and fine grinding and polishing. Due to the significant difference in thermal expansion coefficients and elastic moduli between the polycrystalline diamond layer and the cemented carbide layer, cracks often form at the interface due to large residual thermal and compressive stresses during use, leading to separation of the polycrystalline diamond layer from the cemented carbide layer and failure.

[0003] The bonding strength between the two is a key focus of polycrystalline diamond composite sheet research. Existing solutions mainly optimize the interface composition and structure. Interface composition can be controlled by adding an interface transition layer, modifying powder, and designing novel binders. The working principle is to promote the formation of carbides or diamond coating at the interface, prevent Co from corroding the diamond, promote metallurgical bonding at the interface, and alleviate the differences in physical properties between cemented carbide and diamond. The transition layer can be one or more layers, including metallic transition layers such as W, Ti, Cr, Cu, Ni, and Ni-Mo alloys; ceramic transition layers such as amorphous silicon, TiC, TiN, SiC, and Si3N4; and composite transition layers such as Cr / CrN / Cr, Ti / TiN / Ti, and Ti / TiCN. Powder modification mainly targets diamond for modification / coating, applying Ti, Ni, W, B, Si, etc., to the diamond surface, followed by a sintering reaction to cover it with a stable carbide / oxide film or surface metallization. Novel binders include multi-element alloy binders such as Co-Ni and Co-Ni-Fe, inorganic binders such as carbonates and boron carbide, and metal-ceramic binders. Among these, Co is the most widely used and mature binder in commercial PDC products.

[0004] Current interface structure optimization mainly focuses on the design of the substrate surface. The substrate used in the current PDC is a sintered cemented carbide block. Interface structure optimization involves directly creating grooves on the surface of the cemented carbide substrate through machining processes such as wire cutting or injection / molding to form microstructures such as protrusions of different shapes (snowflake-shaped, concentric circles), and steps. This increases the interfacial contact area between diamond and cemented carbide, alleviates the thermal residual stress and tensile stress at the interface during sintering and operation, and ultimately enhances the interfacial bonding strength.

[0005] Due to the significant differences in physical properties between cemented carbide and diamond, adjusting the interfacial bonding strength through composition design is extremely difficult, has a long development cycle, and involves a certain degree of uncertainty. Interfacial structure design is a recognized method for effectively improving polycrystalline diamond composite sheets under the same composition conditions. However, traditional manufacturing processes are based on sintered cemented carbide matrices. The high hardness of cemented carbide results in low processing efficiency and high cost, which is not conducive to mass production. Considering product performance and production cycle, interfacial microstructures with larger contact areas, such as honeycomb or multi-step designs, have low commercial value for PDCs.

[0006] Powder extrusion printing is an additive manufacturing technology based on powder injection molding (PIM). Its molding principle involves uniformly mixing the target powder with a polymer binder to form a feedstock. The target structure is then converted into a two-dimensional structure recognizable by a 3D printer using slicing software. The viscous feedstock is then extruded through a heated hopper to form a green preform of the target structure. After debinding and sintering, the finished product is obtained. Leveraging the mature processes, equipment, and personnel supply chain of PIM technology significantly shortens the research and development cycle.

[0007] Currently, there are no reports on the application of powder extrusion printing technology in PDC preparation. Summary of the Invention

[0008] Existing polycrystalline diamond composite sheets suffer from difficulties in forming complex interface structures and still fall under the category of weak metallurgical bonding at the interface of two-layer materials, lacking sufficient mechanical bonding. This invention provides a simplified method for preparing complex interface structures, and even macro- and micro-mechanically interlocked structures, by forming a target structure green sample using bimaterial extrusion additive manufacturing technology, followed by synergistic debinding, sintering, high-temperature and high-pressure treatment, and post-processing. This increases the design freedom of the interface structure and enhances the interfacial bonding strength between the cemented carbide matrix and polycrystalline diamond.

[0009] This invention enables the integrated molding of heterogeneous structures made of diamond and cemented carbide by using multiple extruders for simultaneous printing, providing a convenient new method for the development and fabrication of high-performance PDC products with complex interface structures.

[0010] This invention discloses a method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing, comprising:

[0011] 1) Diamond feed preparation: Diamond feed is prepared by mixing and granulation using organic polymers, binders, and diamond as raw materials. Specifically, the diamond and binder are pre-mixed mechanically until uniform (raw material d90 < 50 μm), with a mass ratio of 70-95:5-30, preferably 80-90:10-20; the powder loading of diamond + binder is 45-56 vol.%, preferably 48-53 vol.%.

[0012] 2) Preparation of cemented carbide feedstock: Cemented carbide feedstock is prepared by mixing, kneading and granulation of organic polymer and cemented carbide powder as raw materials.

[0013] When manufacturing cemented carbide feedstock, the molding compatibility with diamond feedstock printing stage and the shrinkage matching of debinding and sintering stage are considered. Both use the same organic polymer system and the same powder loading amount.

[0014] The organic polymer comprises fillers, a backbone, plasticizers, and surfactants, with a mass ratio of 55-75:20-40:2-5:1-5. The fillers include one or more of solid paraffin (PW), liquid paraffin (LPW), and microcrystalline wax (MW), preferably a mixture of PW and MW. The backbone comprises one or more of vegetable oil (EO), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), and ethylene-vinyl acetate copolymer (EVA), preferably a mixture of HDPE and EVA. The plasticizer is selected from at least one of dioctyl phthalate (DOP), dibutyl phthalate (DBP), tricresyl phosphate (TCP), and tributyl citrate (TBC), preferably DOP. The surfactant is selected from at least one of stearic acid (SA) and oleic acid, preferably SA.

[0015] 3) Two-dimensional structure construction: Based on the target three-dimensional structure model, the three-dimensional structure is converted into a multi-layer two-dimensional structure diagram that can be recognized by the printing equipment through slicing software;

[0016] 4) Extrusion Printing: The diamond feedstock and cemented carbide feedstock obtained in steps 1) and 2) are placed into different hoppers of the extrusion 3D printer. The nozzle size and printing layer thickness are selected according to the target structural accuracy. Printing strategy parameters such as extrusion temperature, printing platform temperature, and infill flow rate are set. The modeling and slicing file is imported, and printing is performed according to the set program to obtain a diamond-cemented carbide composite green body.

[0017] 5) Degreasing: Degreasing the diamond-hard carbide composite green blank; to obtain the degreased composite green blank;

[0018] 6) Pre-sintering: Place the degreased composite green body from step 5) in a vacuum furnace for pre-sintering to give the green body a certain strength. The pre-sintering temperature is 800-1000℃ and the holding time is 1-2h. During pre-sintering, the oxygen partial pressure in the furnace is less than or equal to 10Pa.

[0019] 7) High-temperature and high-pressure sintering: The composite material with a certain strength obtained in step 6) is assembled into a high-temperature and high-pressure synthetic block, and then synthesized in a hexahedral press under high temperature and high pressure. The synthesis process is as follows: pressure: 5-7.5 GPa, preferably 7-7.5 GPa; temperature: 1400-1700℃, preferably 1450-1550℃.

[0020] This invention discloses a method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing. The binder is selected from at least one of Ni-Mo, Al-Si, Co, Co-Ni, Co-Ni-Fe, CaCO3, etc., preferably Co.

[0021] This invention discloses a method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing, wherein the diamond particle size is less than or equal to 40 micrometers, preferably 0.5-15 micrometers, and more preferably 7-10 micrometers.

[0022] This invention discloses a method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing, wherein the particle size of the cemented carbide is less than or equal to 20 micrometers, preferably less than or equal to 10 micrometers, and more preferably 0.5-3 micrometers.

[0023] This invention discloses a method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing, wherein the particle size of the binder is less than 10 micrometers, preferably 0.5-3 micrometers.

[0024] In this invention, considering the dual-material formability of cemented carbide feed and diamond feed, as well as the coordinated deformation and shrinkage during debinding and sintering, organic polymers of the same system and powder loading of the same amount are used.

[0025] In this invention, during extrusion printing, a nozzle size of 0.1-0.8 mm is generally selected; during printing, the single-layer thickness is 0.1-0.2 mm, the extrusion temperature is set to 120-140℃, the printing platform temperature is 70-100℃, the filling flow rate is 50-100%, and other parameters are as follows: filling speed 10-40 mm / s, the line width is consistent with the nozzle size, the upper and lower layer line directions are [0, 90°], and the single-layer line method is one of straight line, serrated, or concentric circle.

[0026] In this invention, the parameters used are the same when printing cemented carbide feed and printing diamond feed.

[0027] In this invention, the target three-dimensional structure includes a cemented carbide feed section, a transition section, and a diamond feed section; wherein the transition section is connected to both the cemented carbide feed section and the diamond feed section; the transition section simultaneously contains both cemented carbide feed and diamond feed; and the shape formed by the cemented carbide feed in the transition section is complementary to the shape formed by the diamond feed. Alternatively, the target three-dimensional structure includes both a cemented carbide feed section and a diamond feed section.

[0028] Preferably, in the target three-dimensional structure, when the components from bottom to top are a cemented carbide feed section, a transition section, and a diamond feed section, the cemented carbide feed used in the transition section is raised and enclosed within the diamond feed, relative to the cemented carbide feed section.

[0029] In the transition section, relative to the cemented carbide feed section, the cemented carbide feed used therein is convex and covers the diamond feed.

[0030] Preferably, in the target three-dimensional structure, the protruding cemented carbide feedstock in the transition section is vertically projected, and the resulting shape is at least one of polygon, circle, ellipse, cross, and T-shape; or the diamond feedstock in the transition section is vertically projected, and the resulting shape is at least one of polygon, circle, ellipse, cross, and T-shape, and the projection of the diamond feedstock in the transition section is complementary to the projection of the cemented carbide feedstock. A regular hexagon is preferred. In industrial applications, the transition section is designed as a honeycomb structure, and the honeycomb wall material can be either cemented carbide feedstock or diamond feedstock. The hollow portions in the honeycomb are filled with either diamond feedstock or cemented carbide feedstock.

[0031] In this invention, solvent degreasing can be used. For example, the diamond-hard alloy composite green body is placed in a degreasing solvent to remove low molecular weight organic polymers such as paraffin, DOP, and SA. Then, a vacuum thermal degreasing process is designed based on the polymer thermogravimetric curve to remove the remaining high molecular weight organic polymers. The solvent degreasing process is carried out at 30-60℃ for 12-36 hours.

[0032] Since the degreasing and docking process of this invention is pre-sintering, it is possible to consider using the heating stage in the early stage of pre-sintering for further degreasing and strengthening.

[0033] In this invention, the degreased composite green embryo from step 5) is placed in a vacuum furnace for pre-sintering to give the green embryo a certain strength. The pre-sintering temperature is 800-1000℃ and the time is 1-2 hours. In industrial applications, a heating rate of 0.5-2℃ / min can be used.

[0034] After completing step 7) of the present invention, post-processing can be performed. Specifically, the molybdenum cup / zirconium cup is removed by sand milling, and then the polycrystalline diamond composite sheet with the target complex interface structure is obtained by post-processing such as coarse and fine grinding.

[0035] This invention discloses a method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing. The resulting product has a Vickers hardness of 40-50 GPa, preferably 48-50 GPa, in the PCD layer; and a wear ratio of 31 × 10⁻⁶. 4 ~46×10 4 The preferred size is 36×10. 4 ~37×10 4 Impact toughness is 546-731J.

[0036] This invention uses diamond with an average particle size of 8.9 μm to achieve a wear ratio of 31 × 10⁻⁶. 4 ~46×10 4 This is a product that is clearly superior to existing technologies.

[0037] Principles and advantages

[0038] This invention is the first to attempt a route that first prepares diamond feedstock and cemented carbide feedstock, and then uses extrusion printing molding and pre-sintering and high temperature and high pressure sintering processes to fundamentally strengthen the bonding strength of polycrystalline diamond and cemented carbide, and improve the heat resistance and impact resistance of polycrystalline diamond composite sheets.

[0039] The powder extrusion printing method for preparing complex interface polycrystalline diamond composite sheets developed in this invention, through the rational design of diamond / hard alloy feed formulations, printing strategies, degreasing processes, pre-sintering processes, and high-temperature and high-pressure processes, controls the molding bonding of diamond layers and hard alloy layers and the shrinkage during degreasing and sintering. This provides a new solution for molding complex interface PDC structures, enabling the design of complex interface structures and assisting in the rapid development of high-performance PDC products. Attached Figure Description

[0040] Figure 1 This is a three-dimensional interface structure diagram of the present invention containing a honeycomb interface structure;

[0041] Figure 2 This is a three-dimensional interface structure diagram of the present invention containing a groove interface structure;

[0042] Figure 3 A 3D interface structure diagram of a planar interface structure;

[0043] Figure 4 This is a microstructure diagram of the product obtained in Example 3;

[0044] Figure 5 This is a photograph of the printed green blank obtained in Example 3. Detailed Implementation

[0045] Example 1

[0046] Step 1

[0047] Prepare Co powder, diamond micro powder, and YG10 cemented carbide powder; the average particle size of Co powder is 1.2 μm, the average particle size of diamond is 8.9 μm, and the average particle size of YG10 is 1.7 μm; wherein, diamond and Co are weighed and mixed at a mass ratio of 9:1 to obtain polycrystalline diamond raw material mixed powder.

[0048] Step Two

[0049] Organic polymers were formulated with a mass ratio of PW:MW:EO:EVA:HDPE:DOP:SA of 45:10:5:16:17:5:2; and a volume ratio of organic polymer to polycrystalline diamond raw material powder / YG10 powder of 48:52 (meaning, by volume, organic polymer:polycrystalline diamond raw material powder = 48:52, organic polymer:YG10 powder = 48:52). PW, MW, EO, EVA, HDPE, and DOP were added sequentially to a mixer in descending order of melting point and heated until homogeneous. SA was added simultaneously with the powders in three batches, with cooling during this period to allow for thorough shearing and kneading of the powders and organic polymers to ensure uniform mixing. The cooled mixer was then crushed and sieved to obtain the target feed particles. The mixing temperature was 145℃, the cooling time was 125℃-30min, the total mixing time was 2h, and the feed particle size was 6-12 mesh.

[0050] Step 3

[0051] The designed honeycomb-shaped 3D interface structure PDC model was imported into the printing and slicing software. Two extrusion heads were set for each of the upper and lower layers, and the printing strategy parameters for each head were configured in the software: nozzle size 0.8 mm, layer thickness 0.15 mm, extrusion temperature 125℃, infill flow rate 70%, printing platform temperature 80℃, infill speed 30 mm / s, line width 0.8 mm, single-layer line routing as a straight line, and upper layer line routing direction [0, 90°]. The prepared diamond feedstock and cemented carbide feedstock were then placed into the two hoppers of the extrusion 3D printer, and printing was performed according to the preset parameters.

[0052] Step Four

[0053] The printed preform undergoes solvent degreasing, thermal degreasing, and pre-sintering. The solvent degreasing temperature is 40℃, and the solution is n-heptane for 12 hours. The thermal degreasing process involves heating at 2℃ / min to 400℃ and holding for 1 hour, then slowly heating at 1℃ / min to 500℃ and holding for 1 hour, followed by pre-sintering at 2℃ / min to 900℃ and holding for 1.5 hours.

[0054] Step 5

[0055] The pre-sintered body was placed in a molybdenum cup, and NaCl, carbon nanotubes, pyrophyllite, conductive sheet, and graphite sheet were sequentially assembled into a high-temperature and high-pressure composite block for high-temperature and high-pressure sintering to obtain a polycrystalline diamond composite sheet. The high-temperature and high-pressure process was 1500℃-7.5GPa, with a holding time of 10min.

[0056] The prepared PDC green embryos exhibited regular morphology with a dimensional deviation of <5% and a relative density of 98%. Solvent degreasing showed no bubbling or cracking defects. After high temperature and high pressure treatment, the radial shrinkage was 11.5%, and the axial shrinkage was 10.3%. The microstructure was uniform, the Vickers hardness of the PCD layer was 48 GPa, and the wear ratio was 37 × 10⁻⁶. 4 Its impact toughness is 712J.

[0057] Example 2

[0058] The honeycomb interface structure described in step three is replaced with a planar interface structure, while other steps and parameters remain unchanged. The prepared PDC has a uniform microstructure, a Vickers hardness of 49 GPa, and an abrasion ratio of 36 × 10⁻⁶. 4 Its impact toughness is 546J.

[0059] Example 3

[0060] The honeycomb interface structure described in step three is replaced with a grooved interface structure, while other steps and parameters remain unchanged. The prepared PDC has a uniform microstructure, a Vickers hardness of 49 GPa, and an abrasion ratio of 36 × 10⁻⁶. 4 Its impact toughness is 635J.

[0061] Example 4

[0062] In step one, diamond and Co were weighed and mixed at a mass ratio of 8:2 to obtain polycrystalline diamond raw material mixed powder, with other steps and parameters remaining unchanged. The prepared PDC green embryo had a regular morphology, dimensional deviation <5%, relative density of 98%, and no bubbling or cracking defects after solvent degreasing. After high temperature and high pressure, the radial dimension shrinkage was 10.5%, the axial dimension shrinkage was 8.8%, the microstructure was uniform, the Vickers hardness of the PCD layer was 40 GPa, and the PDC wear ratio was 31 × 10⁻⁶. 4 Its impact toughness is 731J.

[0063] Example 5

[0064] Step 1

[0065] Prepare Co powder, diamond micro powder, and YG10 cemented carbide powder; the average particle size of Co powder is 1.2 μm, the average particle size of diamond is 18.4 μm, and the average particle size of YG10 is 1.7 μm; wherein, diamond and Co are weighed and mixed at a mass ratio of 9:1 to obtain polycrystalline diamond raw material mixed powder.

[0066] Step Two

[0067] Organic polymers were formulated with a mass ratio of PW:MW:EO:EVA:HDPE:DOP:SA = 45:10:5:16:17:5:2; and a volume ratio of organic polymer:polycrystalline diamond raw material powder / YG10 powder = 48:52. PW, MW, EO, EVA, HDPE, and DOP were added sequentially to a mixer in descending order of melting point and heated until homogeneous. SA was added simultaneously with the powders in three batches, with cooling during this process to allow for thorough shearing and kneading of the powders and organic polymers to ensure uniform mixing. The cooled mixer was then crushed and sieved to obtain the target feed pellets. The mixing temperature was 145℃, the cooling time was 125℃-30min, the total mixing time was 2h, and the feed sieve particle size was 6-12 mesh.

[0068] Step 3

[0069] The designed honeycomb-shaped 3D interface structure PDC model was imported into the printing and slicing software. Two extrusion heads were set for each of the upper and lower layers, and the printing strategy parameters for each head were configured in the software: nozzle size 0.8 mm, layer thickness 0.15 mm, extrusion temperature 125℃, infill flow rate 90%, printing platform temperature 80℃, infill speed 30 mm / s, line width 0.8 mm, single-layer line routing as a straight line, and upper layer line routing direction [0, 90°]. The prepared diamond feedstock and cemented carbide feedstock were then placed into the two hoppers of the extrusion 3D printer, and printing was performed according to the preset parameters.

[0070] Step Four

[0071] The printed preform undergoes solvent degreasing, thermal degreasing, and pre-sintering. The solvent degreasing temperature is 40℃, and the solution is n-heptane for 12 hours. The thermal degreasing process involves heating at 2℃ / min to 400℃ and holding for 1 hour, then slowly heating at 1℃ / min to 500℃ and holding for 1 hour, followed by pre-sintering at 2℃ / min to 900℃ and holding for 1.5 hours.

[0072] Step 5

[0073] The pre-sintered body was placed in a molybdenum cup, and NaCl, carbon nanotubes, pyrophyllite, conductive sheet, and graphite sheet were sequentially assembled into a high-temperature and high-pressure composite block for high-temperature and high-pressure sintering to obtain a polycrystalline diamond composite sheet. The high-temperature and high-pressure process was 1500℃-7.5GPa, with a holding time of 10min.

[0074] The prepared PDC green embryos exhibited regular morphology with a dimensional deviation of <8% and a relative density of 92%. Solvent degreasing showed no bubbling or cracking defects. After high temperature and high pressure treatment, the radial shrinkage was 14.2%, and the axial shrinkage was 12.8%. The microstructure was uniform, the Vickers hardness of the PCD layer was 44 GPa, and the PDC wear ratio was 46 × 10⁻⁶. 4The impact toughness is 687J. Due to the elimination of most internal defects in the product by high temperature and high pressure, the prepared PDC has good comprehensive performance. However, due to the large particle size of the raw material, the feeding and extrusion are not smooth, resulting in low green density. After degreasing, pre-calcination and high temperature and high pressure, the product size shrinkage and deformation are large, and the consistency of large-scale production is low.

[0075] Example 6

[0076] Other conditions were the same as in Example 1, except that the degreasing temperature in step four was adjusted to 70℃, while other steps and parameters remained unchanged. The prepared PDC preform bubbled and cracked during solvent degreasing due to excessively high temperature and rapid degreasing rate. Microcracks were still visible after pre-sintering. After high temperature and high pressure, the sample showed a radial shrinkage of 12.5% ​​and an axial shrinkage of 10.9%, a slight increase in dimensional shrinkage. The microstructure was uniform, the Vickers hardness of the PCD layer was 47 GPa, and the PDC wear ratio was 35 × 10⁻⁶. 4 The impact toughness is 694J. High temperature and high pressure eliminate most internal defects in the product, with little impact on the final product performance.

[0077] Comparative Example 1

[0078] Step 1

[0079] Prepare Co powder, diamond micro powder, and YG10 cemented carbide powder; the average particle size of Co powder is 1.2 μm, the average particle size of diamond is 8.9 μm, and the average particle size of YG10 is 1.7 μm; wherein, diamond and Co are weighed and mixed at a mass ratio of 9:1 to obtain polycrystalline diamond raw material mixed powder.

[0080] Step Two

[0081] Organic polymers were formulated with a mass ratio of PW:MW:EO:EVA:HDPE:DOP:SA of 45:10:5:16:17:5:2; and a volume ratio of organic polymer to polycrystalline diamond powder of 48:52, and organic polymer to YG10 powder of 43:57. PW, MW, EO, EVA, HDPE, and DOP were added sequentially to a mixer in descending order of melting point and heated until homogeneous. SA was added simultaneously with the powder in three batches, with cooling during this process to allow for thorough shearing and kneading of the powder and organic polymers to ensure uniform mixing. The cooled mixer was then crushed and sieved to obtain the target feed pellets. The mixing temperature was 145℃, the cooling time was 125℃-30min, the total mixing time was 2h, and the feed pellet size was 6-12 mesh.

[0082] Step 3

[0083] The designed honeycomb-shaped 3D interface structure PDC model was imported into the printing and slicing software. Two extrusion heads were set for each of the upper and lower layers, and the printing strategy parameters for each head were configured in the software: nozzle size 0.8mm, layer thickness 0.15mm, printing platform temperature 80℃, infill speed 30mm / s, trace width 0.8mm, single-layer trace pattern straight line, and upper layer trace direction [0, 90°]. The diamond feed extrusion temperature was 125℃, and the infill flow rate was 70%; the YG10 feed base temperature was 130℃, and the infill flow rate was 85%. The prepared diamond feed and cemented carbide feed were then placed into the two hoppers of the extrusion 3D printer, and printing was performed according to the preset parameters.

[0084] Step Four

[0085] The printed preform undergoes solvent degreasing, thermal degreasing, and pre-sintering. The solvent degreasing temperature is 40℃, and the solution is n-heptane for 12 hours. The thermal degreasing process involves heating at 2℃ / min to 400℃ and holding for 1 hour, then slowly heating at 1℃ / min to 500℃ and holding for 1 hour, followed by pre-sintering at 2℃ / min to 900℃ and holding for 1.5 hours.

[0086] The prepared PDC green embryos have regular morphology, dimensional deviation <8%, and relative density of 97%. Solvent degreasing showed no bubbling or cracking defects. After pre-sintering, the samples deformed significantly due to inconsistent shrinkage rates. Specifically, the cemented carbide layer shrank radially by 7.2%, and the diamond layer shrank radially by 8.9%, accompanied by edge collapse deformation of the diamond layer.

[0087] Comparative Example 2

[0088] Other conditions were the same as in Example 1, except that in step 2, the volume ratio of organic polymer to polycrystalline diamond raw material powder / YG10 was 43:57, while other steps and parameters remained unchanged. The resulting diamond feedstock was viscous and had poor flowability. During the printing process, with the printing extrusion temperature set at 125°C, adjusting parameters such as flow rate, layer thickness, and nozzle size did not result in smooth extrusion. Increasing the printing extrusion temperature to 140°C resulted in smooth extrusion, but significant overflow was observed near the nozzle, and the extrusion volume was unstable. This was due to excessive feedstock loading; the viscosity was high at normal printing temperatures, and increasing the printing temperature caused phase separation extrusion of the feedstock.

Claims

1. A method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing, characterized in that: Includes the following steps: 1) Diamond feed preparation: Diamond feed is prepared by mixing and granulation using organic polymers, binders, and diamond as raw materials. The diamond and binder are pre-mixed mechanically to a uniform mass ratio of 80-90:10-20. The powder loading of diamond + binder in the diamond feed is 48-53 vol.%; the raw material d90 < 50 μm; the binder is selected from at least one of Ni-Mo, Al-Si, Co, Co-Ni, and Co-Ni-Fe; the particle size of the diamond feed is less than or equal to 40 micrometers; the particle size of the diamond is 7-10 micrometers, and the particle size of the binder is 0.5-3 micrometers. 2) Preparation of cemented carbide feedstock: Cemented carbide feedstock is prepared by mixing, kneading, and granulation of organic polymers and cemented carbide powder as raw materials. The loading of cemented carbide powder in the feedstock is 48-53 vol.%. When manufacturing cemented carbide feedstock, considering its molding compatibility with diamond feedstock in the printing stage and shrinkage matching in the debinding and sintering stage, both use the same organic polymer system and the same powder loading. The particle size of cemented carbide feedstock is less than or equal to 20 micrometers. The particle size of cemented carbide is 0.5-3 micrometers. 3) Two-dimensional structure construction: Based on the target three-dimensional structure model, the three-dimensional structure is converted into a multi-layer two-dimensional structure diagram that can be recognized by the printing equipment using slicing software; 4) Extrusion Printing: The diamond feedstock and cemented carbide feedstock obtained in steps 1) and 2) are placed into different hoppers of the extrusion 3D printer. The nozzle size and printing layer thickness are selected according to the target structural accuracy. The printing strategy parameters are set, including extrusion temperature, printing platform temperature, and infill flow rate. The modeling and slicing file is imported, and printing is performed according to the set program to obtain a diamond-cemented carbide composite green body. During extrusion printing, the nozzle size is 0.1-0.8mm. During printing, the single layer thickness is 0.1-0.2mm. The extrusion temperature is set to 120-140℃, the printing platform temperature is 70-100℃, and the infill flow rate is 50-100%. Other parameters are as follows: infill speed 10-40mm / s, the line width is consistent with the nozzle size, the upper and lower layer line direction is [0, 90°], and the single layer line method is one of straight line, serrated, or concentric circle. 5) Degreasing: Degreasing the diamond-hard carbide composite green blank; to obtain the degreased composite green blank; 6) Pre-sintering: Place the degreased composite green body from step 5) in a vacuum furnace for pre-sintering to give the green body a certain strength. The pre-sintering temperature is 800-1000℃ and the holding time is 1-2 hours. During pre-sintering, the oxygen partial pressure in the furnace is less than or equal to 10 Pa. 7) High-temperature and high-pressure sintering: Assemble the pre-fired composite with a certain strength from step 6) into a high-temperature and high-pressure composite block, and place it in a hexahedral press for high-temperature and high-pressure synthesis; the synthesis pressure is 5-7.5 GPa and the temperature is 1400-1700℃; The organic polymer comprises filler, backbone, plasticizer, and surfactant in a mass ratio of 55-75:20-40:2-5:1-5. The filler comprises one or more of solid paraffin, liquid paraffin, and microcrystalline wax. The backbone comprises one or more of vegetable oil, high-density polyethylene, low-density polyethylene, polypropylene, and ethylene-vinyl acetate copolymer. The plasticizer is selected from at least one of dioctyl phthalate, dibutyl phthalate, tricresyl phosphate, and tributyl citrate. The surfactant is selected from at least one of stearic acid and oleic acid.

2. The method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing according to claim 1, characterized in that: The adhesive is Co.

3. The method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing according to claim 1, characterized in that: The target three-dimensional structure includes a cemented carbide feed section, a transition section, and a diamond feed section; The transition section is connected to the cemented carbide feed section and the diamond feed section; the transition section contains both cemented carbide feed and diamond feed; and the shape formed by the cemented carbide feed in the transition section is complementary to the shape formed by the diamond feed. Alternatively, the target three-dimensional structure may include a cemented carbide feed section and a diamond feed section.

4. The method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing according to claim 1, characterized in that: Degreasing is carried out by solvent degreasing; the solvent degreasing process is carried out at 30-60℃ for 12-36 hours.

5. The method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing according to claim 1, characterized in that: The degreased composite green embryo from step 5) is placed in a vacuum furnace for pre-sintering to give the green embryo a certain strength. The pre-sintering temperature is 800-1000℃ and the time is 1-2h.

6. A method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing according to any one of claims 1-5, characterized in that: The obtained product has a Vickers hardness of 40-50 GPa for the PCD layer and a wear ratio of 31 × 10⁻⁶. 4 ~46×10 4 Impact toughness is 546-731J.

7. The method for preparing complex interface polycrystalline diamond composite sheets based on powder extrusion printing according to claim 6, characterized in that: The obtained product has a Vickers hardness of 48-50 GPa for the PCD layer; the wear ratio of the product is 36×10. 4 ~37×10 4 Impact toughness is 546-731J.

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