A PDC substrate containing a high-impact toughness structural transition layer and its preparation method and application

Abstract

The present invention relates to a PDC substrate containing a high-impact toughness structural transition layer and its integrated preparation method and application; it belongs to the field of PDC design and preparation technology. The PDC substrate containing a high-impact toughness structural transition layer of the present invention comprises a cemented carbide substrate and a transition layer; the cemented carbide substrate is composed of cemented carbide, and the transition layer is composed of N sub-transition layers, and any one of the sub-transition layers contains a diamond region and a cemented carbide region; wherein the cemented carbide content in the diamond region is less than the cemented carbide content in the cemented carbide region, and the diamond content in the diamond region is greater than the diamond content in the cemented carbide region. Its preparation method comprises preparing a printed blank by an extrusion molding process, and then obtaining the product by degreasing and sintering. After the transition layer of the product obtained by the present invention contacts diamond, a high-temperature and high-pressure synthesis process is adopted to obtain a high-quality PDC. The substrate structure of the present invention is reasonably designed and the preparation process is simple. The PDC obtained after compounding with diamond has excellent performance and is convenient for industrial application.

Description

Technical Field

[0001] The invention relates to a PDC substrate containing a high-impact toughness structural transition layer, an integrated preparation method and application thereof, and belongs to the technical field of PDC design and preparation. Background Art

[0002] Polycrystalline diamond compacts (PDCs) are formed by sintering a diamond layer and a cemented carbide substrate under high temperature and high pressure. They combine the high hardness and wear resistance of diamond with the high strength and impact toughness of cemented carbide, and are widely used in oil drilling, geological drilling, engineering drilling, and mechanical processing. However, due to the significant difference in the elastic modulus and thermal expansion coefficients of diamond and cemented carbide, severe residual stress exists at the interface between the PDC layer and the cemented carbide substrate. This can lead to PDC failures, such as delamination between the PDC layer and the cemented carbide substrate.

[0003] The existing PDC substrate is generally cemented carbide. For example, patent CN110545959A introduces energy-processed polycrystalline diamond composite sheets and related methods. The substrate involved is a simple cemented carbide layer, and it does not involve a transition layer. Some people have also tried to use a transition layer to inhibit the diffusion of cobalt elements from the cemented carbide substrate to the polycrystalline diamond layer. For example, patent CN201910789690.6 introduces a silicon carbide-diamond transition layer and a polycrystalline diamond layer on the surface of a cemented carbide substrate. However, it does not involve how to design the structure of the transition layer, nor does it involve the use of cemented carbide and diamond partitioning in the transition layer. There is no report on the formation of a transition zone by regulating different diamond contents.

[0004] At the same time, the search found that there are few reports on the technology of using extrusion 3D printing to prepare high-quality PDC substrates with cross-structured transition layers. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention has designed for the first time a transition layer composed of diamond and cemented carbide partitions and attached the transition layer to a substrate composed of cemented carbide, thereby obtaining a high-quality PDC substrate. At the same time, the present invention has also developed an extrusion 3D printing process that matches it.

[0006] This patent proposes a high impact toughness structure, which is composed of a hard material and a soft material, wherein the elastic modulus of the soft material is lower than that of the hard material. The soft material layer is sandwiched between the hard material layers, and the hard material layer is penetrated by the soft material in a grid-like structure, and the soft material grids are staggered in the adjacent hard material layers. According to this structure, a transition layer with high impact toughness is made using cemented carbide as the soft material and diamond as the hard material and applied to the preparation of PDC. On the one hand, it alleviates the difference in elastic modulus and thermal expansion coefficient between the cemented carbide substrate and the polycrystalline diamond layer; on the other hand, it utilizes the characteristics of the high impact toughness structure in scattering stress waves and extending the crack propagation path to inhibit the initiation and propagation of cracks at the PDC interface, thereby improving the interface bonding strength and impact resistance of the polycrystalline diamond composite sheet.

[0007] The present invention discloses a PDC substrate containing a high-impact toughness structural transition layer, comprising a cemented carbide substrate and a transition layer; the cemented carbide substrate is composed of cemented carbide, the transition layer comprises N sub-transition layers, and any one of the sub-transition layers contains a diamond region and a cemented carbide region; the cemented carbide content in the diamond region is less than that in the cemented carbide region, and the diamond content in the diamond region is greater than that in the cemented carbide region.

[0008] The present invention provides a PDC substrate containing a high-impact toughness structural transition layer, wherein the total thickness of the transition layer is 0.2-3 mm, preferably 0.5-2 mm.

[0009] Preferably, the present invention provides a PDC substrate with a high-impact toughness structural transition layer. In a first embodiment, any sub-transition layer comprises a cemented carbide mesh, filled with diamond filler within the mesh; the meshes in adjacent sub-transition layers are offset. Specifically, in the first embodiment, projection is made perpendicular to any sub-transition layer. In the projected sub-transition layer, the cemented carbide region forms a mesh line, the mesh line enclosing a grid, and the diamond filler within the mesh; the meshes in adjacent sub-transition layers are offset.

[0010] Preferably, the total thickness of the diamond region is greater than or equal to 0.1 mm.

[0011] Preferably, the number of sub-transition layers is greater than or equal to 3.

[0012] As a further preferred solution, in Solution 1, the width of the cemented carbide grid lines is less than 1.2 mm. The diamond content in the cemented carbide grid lines is less than the diamond content in the diamond filler.

[0013] Preferably, the offset is 1 / 8 to 2 / 3 of the area of ​​the minimum grid, and the offset angle is 15 to 45° (ie, the offset direction is 15 to 45°).

[0014] Preferably, in the first embodiment of the present invention, a PDC substrate containing a high impact toughness structural transition layer is provided, wherein a cemented carbide layer is further distributed between adjacent sub-transition layers.

[0015] In the first solution, a cemented carbide layer is provided between adjacent sub-transition layers, and the diamond content of the cemented carbide layer is less than or equal to the diamond content in the cemented carbide grid.

[0016] As a further preference, in solution 1, the volume fraction of the cemented carbide grid in the diamond layer is smaller than the volume fraction of the diamond block.

[0017] Preferably, the present invention provides a PDC substrate containing a high impact toughness structural transition layer, in option 2, wherein any sub-transition layer is composed of alternating carbide rings and diamond rings, the carbide rings and diamond rings are in a concentric circle structure, and the diamond content in the carbide rings is less than the diamond content in the diamond rings.

[0018] As a further preferred embodiment, in a PDC substrate with a high-impact toughness structural transition layer according to the present invention, in Option 2, the cemented carbide rings and / or diamond rings in adjacent sub-transition layers are offset. The offset is 1 / 5 to 2 / 3 the thickness of the diamond ring, i.e., the thickness of any cemented carbide ring increases to occupy 1 / 5 to 2 / 3 of the thickness of the diamond ring.

[0019] As a preferred embodiment of the second solution, a hard alloy area is further designed between adjacent sub-transition layers.

[0020] Preferably, the present invention provides a PDC substrate containing a high impact toughness structural transition layer, wherein the transition layer has the arrangements of schemes one and two.

[0021] The cemented carbide substrate is made of WC-Co cemented carbide. The cemented carbide used in the transition layer includes WC-Co cemented carbide.

[0022] In the present invention, the Co content in the WC-Co cemented carbide is 5-25 wt.%; the diamond powder may be mixed with one or more of Co and WC, with a content of 0-30 vol.%.

[0023] As one of the preferred schemes, the present invention provides a PDC substrate containing a high impact toughness structural transition layer, which includes a YG13 substrate and a transition layer, wherein the transition layer is formed by alternatingly stacking Q+1 layers of M layers and Q layers of cemented carbide layers, and in the M layer, M1 is arranged in the form of a grid structure, and M2 is filled in the grid, wherein the M1 is a cemented carbide material or a cemented carbide material containing diamonds, and M2 is a diamond material or a mixed material consisting of cemented carbide and diamonds. When M1 is a cemented carbide material containing diamonds, its diamond content is less than 10 vol.%, and when M2 is a mixed material consisting of cemented carbide and diamonds, its cemented carbide content is less than or equal to 40 vol.%.

[0024] The Q is greater than or equal to 3, preferably greater than or equal to 4, and more preferably greater than or equal to 5.

[0025] As a further preferred solution, the grids of two adjacent sub-transition layers are offset by a certain amount, the offset is 1 / 2 of the square area, and the offset direction is obliquely 45°, thereby obtaining two staggered grids.

[0026] As a further preferred solution, projection is performed perpendicularly to any sub-transition layer, and in the projected sub-transition layer, the carbide area forms a mesh line, and the mesh line forms a grid, and the grid line width is 0.35-0.45 mm.

[0027] The ratio of the sum of the lengths of the four sides of any grid to the grid thickness is preferably 10 to 35:1, more preferably 20 to 28:1. This ratio affects the final toughness of the product, which is also explored for the first time by the present invention.

[0028] As a further preferred solution, when using Option 2, the line width of a single carbide circle is 0.35-0.45 mm. The distance between two adjacent carbide circles, i.e., the length of a single diamond block, has a ratio of 5-35:1 to the diamond thickness; more preferably, 10-35:1, even more preferably, 16-32:1, and even more preferably, 20-28:1. In this case, the product's toughness is far superior to that of the other solutions. This discovery is also a first for the present invention.

[0029] The present invention provides an integrated preparation method for a PDC substrate containing a high-impact toughness structural transition layer, comprising the following steps:

[0030] 1) Diamond feedstock preparation: Diamond powder is mixed with one or more of Co powder and WC powder at a concentration of 0-40 vol.% to prepare M powder. Diamond feedstock is prepared using an organic polymer binder and M powder as raw materials through internal mixing and granulation. M and binder are pre-mixed mechanically (d90 < 50) to form a uniform mass ratio of 70-95:5-30, preferably 80-90:10-20. The M powder + binder loading is 45-65 vol.%, preferably 48-57 vol.%. M powder is referred to as diamond mixed powder. In the present invention, when diamond mixed powder contains only diamond powder, it is also referred to as M powder.

[0031] 2) Cemented Carbide Feedstock Preparation: Prepare cemented carbide powder. The cemented carbide is WC-Co, with a Co mass fraction of 5-25 wt.% and a WC mass fraction of 75-95 wt.%. The cemented carbide feedstock is produced by mixing, kneading, and granulating an organic polymer binder and cemented carbide powder. When manufacturing the cemented carbide feedstock, consider its bonding with the diamond feedstock during the printing phase and shrinkage matching during the debinding and sintering phases. The powder loading is 45-65 vol.%, preferably 50-61 vol.%.

[0032] The organic polymer binder includes a filler, a skeleton, a plasticizer, and a surfactant, with a mass ratio of 55-75:20-40:2-5:1-5 respectively; the filler includes one or more of solid paraffin (PW), liquid paraffin (LPW), and microcrystalline wax (MW), preferably a mixture of PW and MW; the skeleton includes 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; and the surfactant is selected from at least one of stearic acid (SA) and oleic acid, preferably SA.

[0033] 3) 2D structure construction: Model the target 3D structure and convert the 3D structure into

[0034] A multi-layer two-dimensional structure diagram that can be recognized by the printing device;

[0035] 4) Printing Preparation: Place the diamond feedstock and carbide feedstock produced in steps 1) and 2) into different hoppers of the extrusion 3D printer. Select the nozzle size and layer thickness based on the target structural accuracy. Set the extrusion temperature, build platform temperature, fill flow rate, and other printing strategy parameters. Import the modeling slice file.

[0036] 5) Extrusion printing:

[0037] According to the set structure and path, the nozzle size is 0.1-0.8mm, the layer thickness is 0.1-0.2mm, the extrusion temperature is 120-180℃, the filling flow rate is 50-100%, the printing platform temperature is 70-100℃, the filling speed is 10-40mm / s, the routing width is consistent with the nozzle diameter, the single-layer routing method is a straight line, and the upper layer routing direction is [0, 90°]. Extrusion molding is performed to obtain a printed blank. The filling flow rate is based on the inherent extrusion flow rate in the slicing software. On the printer control panel, the actual extrusion amount is adjusted according to the percentage of the inherent flow rate in the slicing software.

[0038] 6) Degreasing and sintering:

[0039] After degreasing, the printed blank is sintered by first vacuuming and then filling with protective gas to obtain a PDC substrate with a high impact toughness structural transition layer; the sintering temperature is 1400-1500°C.

[0040] As a preferred solution, when the model is composed of a carbide substrate and a transition layer from bottom to top, during the printing process, the nozzle with carbide feed placed in the extrusion printer is first started according to the preset parameters and prepares a carbide substrate of a specific size; then the double nozzles are operated in an orderly manner according to the model design to prepare each sub-transition layer on the carbide substrate, wherein the sub-transition layer is formed by alternating stacking of diamond layers and carbide layers, and the area hot-pressed and composited with diamond is a diamond layer, thereby obtaining a high impact toughness structure transition layer-carbide substrate green body; the alternating stacking In the transition layer, the carbide layer is sandwiched between the diamond layers, and the diamond layer is penetrated by the carbide feed in a grid structure, and the carbide grids in adjacent diamond layers are staggered. In the high impact toughness structure transition layer-carbide substrate green body, the total thickness of the transition layer is 0.2-3 mm, preferably 0.5-2 mm. In the transition layer, the thickness of a single diamond layer is not less than 0.1 mm, the number of layers is not less than 3, and the thickness of the carbide layer is 0.1-1 mm. In the single diamond layer, the width of the carbide grid line is less than 1.2 mm.

[0041] In the present invention, degreasing includes solvent degreasing. During solvent degreasing, n-heptane is used as the degreasing solvent, and degreasing is performed at 30-60° C. for 12-36 hours to obtain a degreased composite green body.

[0042] Solvent degreasing generally removes PW, MW, and SA.

[0043] In the present invention, after solvent debinding, thermal debinding and vacuum sintering are performed. Specifically, the debinded composite green body is placed in a vacuum furnace for thermal debinding. The temperature is slowly raised to 550°C in an H2 atmosphere at a flow rate of 40-60 L / min and maintained at this temperature for 40-90 minutes to completely remove the polymer binder. Subsequently, the temperature is continuously raised to 1400-1500°C in a vacuum state, and high-pressure Ar2 is introduced at 3-6 bar and maintained at this temperature for 20-50 minutes. The sample is then cooled in the furnace to obtain a PDC substrate with a high-impact toughness structural transition layer.

[0044] The present invention discloses an application of a PDC substrate comprising a high-impact toughness structural transition layer, comprising: assembling a sintered PDC substrate with a high-impact toughness structural transition layer and diamond powder, such that the transition layer and the diamond powder are in contact, into a high-temperature, high-pressure synthesis block, and then subjecting the block to high-temperature, high-pressure synthesis in a hexahedral press. The synthesis process comprises a pressure of 5-7.5 GPa, preferably 6-7 GPa, and a temperature of 1400-1700°C, preferably 1450-1550°C.

[0045] Principles and advantages

[0046] The present invention is the first to design a PDC substrate composed of N sub-transition layers. The sub-transition layers designed by the present invention contain diamond areas and cemented carbide areas. These two areas can be distributed alternately or cross-distributed, which enhances the toughness of the PDC substrate. At the same time, on this basis, the following optimization schemes are also proposed: "Scheme 1, any sub-transition layer contains cemented carbide to form a grid, and diamond filler is filled in the grid; the grids in adjacent sub-transition layers are offset; Scheme 2, any sub-transition layer is composed of cemented carbide rings and diamond rings distributed alternately, and the cemented carbide rings and diamond rings are in a concentric circle structure, and the diamond content in the cemented carbide rings is less than the diamond content in the diamond rings." These two schemes further enhance the toughness of the product. When the isolation layer is further optimized and introduced, that is, a cemented carbide layer is distributed between adjacent sub-transition layers, the toughness of the product is further enhanced. This design is the first of its kind in the present invention.

[0047] At the same time, the present invention also attempts for the first time to use extrusion additive manufacturing to prepare a PDC substrate with the above-mentioned special structure. With the synergistic effect of various components and processes, the toughness of the product is further improved.

[0048] The present invention utilizes the high fracture toughness of the structure and the high structural design flexibility of extrusion-type additive manufacturing to integrally prepare a high-impact toughness transition layer and a cemented carbide substrate for a polycrystalline diamond compact, thereby alleviating the differences in elastic modulus and thermal expansion coefficient between the cemented carbide substrate and the polycrystalline diamond layer, inhibiting the initiation and propagation of cracks at the PDC interface, and improving the interface bonding strength and impact resistance of the polycrystalline diamond compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the PDC composite sheet with a high impact toughness transition layer designed in Example 1;

[0050] Figure 2 Schematic diagram of the high impact toughness transition layer and cemented carbide substrate designed in Example 1

[0051] Figure 1 、 2 In the figure, black represents diamond, and lead and white represent YG13; in the diamond layer, YG13 is embedded in a grid structure;

[0052] Figure 3 Schematic diagram of the high impact toughness transition layer and cemented carbide substrate designed in Example 3;

[0053] Figure 4 This is a schematic diagram for introducing the aspect ratio in Example 1.

[0054] Figure 5 This is a schematic diagram for introducing the aspect ratio in Example 3. DETAILED DESCRIPTION

[0055] Example 1

[0056] Step 1

[0057] Prepare Co powder, diamond powder, and YG13 cemented carbide powder; the average particle size of Co powder is 1.2 μm, the average particle size of diamond is 10 μm, the average particle size of YG13 is 1.2~1.6 μm, and the density is 14.2 g / cm 3 ; Among them, diamond and Co are weighed and mixed in a mass ratio of 9:1 to obtain diamond-10Co mixed powder.

[0058] Step 2

[0059] The organic polymer was prepared in a mass ratio of PW:MW:EO:EVA:HDPE:DOP:SA = 45:10:5:16:17:5:2; the volume ratio of organic polymer:polycrystalline diamond raw material mixed powder / YG13 powder = 45:55. PW, MW, EO, EVA, HDPE, and DOP were added to an internal mixer in descending order of melting point and heated and mixed until uniform. SA was added simultaneously with the powder in 3-5 batches. The mixture was cooled to allow for thorough shearing and kneading of the powder and organic polymer to ensure uniform mixing. The cooled internal mixer was then crushed and sieved to obtain the desired feed granules. The internal mixing temperature was 145°C, and the cooling temperature-time was 125°C-30 minutes, for a total internal mixing time of 1.5 hours.

[0060] Step 3:

[0061] The model of integrated preparation of high impact toughness transition layer and PDC substrate is designed. The model consists of two parts, from bottom to top: YG13 substrate and YG13+diamond transition layer. The transition layer is composed of 6 layers of diamond layers and 5 layers of YG13 layers stacked alternately, and in the diamond layer, YG13 is embedded in it in a grid structure, such as Figure 1 shown.

[0062] In the YG13+diamond transition layer, the grids in the two adjacent diamond layers are offset by a certain amount. The offset is 1 / 2 of the square area, and the offset direction is oblique 45°, thus obtaining two staggered grids.

[0063] The model has an overall size of φ18.7 × 9.3 mm, with the YG13 substrate measuring φ18.7 × 8.2 mm and the YG13 + diamond transition layer measuring φ18.7 × 1.7 mm. Within the YG13 + diamond transition layer, there are five carbide layers with a thickness of 0.1 mm, and six diamond layers with a thickness of 0.2 mm. The thickness design principle is as follows: assuming the diamond layer is a complete diamond layer without a carbide grid, by adjusting the thickness of the diamond layer and carbide layer in the transition layer, the volume fraction ratio of diamond to carbide in the transition layer is adjusted to ≈ 55:45. The diamond layers are of equal thickness, and the carbide layers are of equal thickness.

[0064] A single diamond polygon in the diamond layer is a polygonal block with a certain height. The average side length is the total side length of the polygonal bottom of the polygon divided by the number of sides, that is, (t1+t2+…+tn) / n, t is the side length of the bottom, and n is the number of sides of the bottom. The ratio of the average side length to the thickness (height) of the diamond layer is the aspect ratio. In this embodiment, the cemented carbide grid is a cube grid with aspect ratios of 16 (Group A), 24 (Group B), and 32 (Group C), respectively, and the grid line width is 0.4 mm. The volume fraction ratio of the total diamond material to the cemented carbide material in the transition layer is diamond material: YG13 material ≈ 55:45,

[0065] The designed integrated high-impact toughness transition layer and PDC substrate model was imported into the corresponding slicing software and extrusion printer at a 1:1 ratio. Two extruders were assigned to the upper and lower layers, and the corresponding printing strategy parameters were set in the software: nozzle size 0.4mm, layer thickness 0.15mm, extrusion temperature 165°C, fill flow rate 90%, print platform temperature 80°C, fill speed 30mm / s, trace width 0.4mm, single-layer trace mode straight, and upper layer trace direction [0, 90°]. The prepared YG13 and diamond-10Co materials were then fed into the two hoppers of the extrusion 3D printer and printed according to the preset parameters.

[0066] Step 4: Degreasing the printed high impact toughness structural transition layer-cemented carbide substrate green body with solvent, wherein the solvent degreasing temperature is 50°C, the degreasing solvent is n-heptane, and the degreasing is carried out for 24 hours;

[0067] Step 5: The degreased high-impact toughness structural transition layer-cemented carbide substrate green body was placed in a furnace with an H2 atmosphere at a flow rate of 50 L / min and slowly heated to 550°C for 1 hour. The temperature was then continuously raised to 1400°C under vacuum, and then high-pressure Ar2 at 5.8 bar was introduced and held for 30 minutes. The sample was then cooled in the furnace to obtain a sintered body of the upper and lower structural transition layers-cemented carbide substrate.

[0068] Step 6

[0069] Diamond-4wt.% Co powder with an average diamond grain size of 20μm and the prepared transition layer-carbide substrate sintered body were placed in a molybdenum cup. NaCl, carbon tubes, pyrophyllite, conductive sheets, and graphite sheets were then assembled into a high-temperature, high-pressure composite block. This was then sintered at high temperature and high pressure to produce a polycrystalline diamond compact (PDC). The high-temperature, high-pressure process was performed at 1500°C and 9.0GPa for 10 minutes to produce the polycrystalline diamond compact (PDC).

[0070] The prepared transition layer-carbide substrate green body exhibited a regular morphology with a dimensional deviation of less than 5%, a relative density of 98%, and no bubbling or cracking defects after solvent degreasing. After vacuum sintering, the YG13 substrate, transition layer, and sample axial dimensions shrank by 16.31%, 16.24%, and 18.31%, respectively. The diamond surface was partially graphitized. Under high temperature and pressure, graphite and diamond dissolved and precipitated to form polycrystalline diamond. The PDC wear ratio for Group A was 37.4 × 10 4 , impact toughness is 1153; PDC wear ratio of group B is 38.2×10 4 , impact toughness is 1395J; the wear ratio of PDC in group C is 39.8×10 4 , the impact toughness is 1281J.

[0071] In this example, wear ratio tests were performed on polycrystalline diamond samples using SiC grinding wheels. Each grinding wheel tested one point on the PDC, with wheel wear controlled at 110-130 grams. Two corresponding points were measured on each PDC, and the results were averaged. Impact resistance was tested using a PDC dynamic load resistance tester. The testing method was as follows: starting with an impact energy of 20J, the sample was tested ten times. If no damage (cracking, delamination, etc.) was observed, the impact energy was increased to 25J and the test continued ten times. If no damage was observed, the impact energy was increased to 30J and the test continued ten times. This process was repeated until damage occurred and testing was stopped. The impact energy multiplied by the number of impacts was the impact energy, and the average value was calculated by testing five times each layer. (The wear ratio and impact toughness testing methods used in the subsequent examples and comparative examples are consistent.)

[0072] Example 2 - Changing layer thickness and number of layers

[0073] Other differences are the same as in Example 1, except that:

[0074] In step 3, the number of YG13 layers in the transition layer was changed to 4, with a thickness of 0.1 mm. The number of diamond layers was changed to 5, with a thickness of 0.2 mm. This resulted in a volume ratio of diamond to YG13 of ≈ 7:3 across the transition layer, ignoring the effect of the carbide mesh in the diamond layer on the diamond volume fraction. The mesh was a cubic mesh with aspect ratios of 6, 8, and 10, respectively, and a mesh width of 0.4 mm. The model had an overall size of φ18.7 × 9.3 mm, with the transition layer measuring φ18.7 × 1.4 mm and the YG13 substrate measuring φ18.7 × 7.9 mm.

[0075] The resulting transition layer-carbide substrate green body had a regular morphology, a dimensional deviation of less than 5%, a relative density of 99%, and no bubbling or cracking defects during solvent degreasing. After vacuum sintering, the YG13 substrate radial dimensions shrank by 16.26%, the transition layer radial dimensions shrank by 16.13%, and the sample axial dimensions shrank by 17.85%. The diamond surface was partially graphitized. Under high temperature and high pressure, graphite and diamond dissolved and precipitated to form polycrystalline diamond. Three groups of PDCs were obtained, with transition layer diamond grid aspect ratios of 6, 8, and 10, respectively, and their wear ratios were 37.9×10 4 , 38.5×10 4 、38.8×10 4 ; The impact toughness is 1090J, 1271J, and 1133J respectively. Example 3

[0076] The transition layer was changed from YG13 grid to YG13 concentric circles, and the diamonds were also made into concentric circles. The steps and parameters of ingredients, molding, degreasing and sintering were the same as those in Example 1. The differences were:

[0077] Replace the YG13 grid that runs through the diamond layer in step 3 with concentric circles of YG13. The thickness of the diamond and YG13 layers remains unchanged, both at 0.1mm, and the number of layers remains unchanged (6 diamond layers, 5 YG13 layers). Concentric circles of YG13 run through the diamond layer, and the concentric circles in two adjacent diamond layers are staggered at a distance that bisects the thickness of the diamond ring. If the core thickness of the diamond concentric circle structure cannot be filled with one circle of diamond and one circle of YG13, it will be filled entirely with diamond. The line width of a single YG13 circle is 0.4mm, and the distance between two YG13 circles is the length of a single diamond block. This length is related to the diamond thickness, and the aspect ratio is 16, 24, or 32.

[0078] The resulting transition layer-carbide substrate green body had a regular morphology, a dimensional deviation of less than 7%, a relative density of 96%, and no bubbling or cracking defects during solvent degreasing. After vacuum sintering, the YG13 substrate radial dimensions shrank by 16.37%, the transition layer radial dimensions shrank by 16.28%, and the sample axial dimensions shrank by 18.29%, with the diamond surface partially graphitized. Under high temperature and high pressure, graphite and diamond dissolved and precipitated to form polycrystalline diamond. Three groups of PDCs were obtained, with transition layer diamond concentric circle aspect ratios of 16, 24, and 32, respectively, and their wear ratios were 38.7×10 4 、39.3×10 4 、36.8×10 4 ; The impact toughness are 1148J, 1318J and 1243J respectively.

[0079] Comparative Example 1—Homogeneous Cemented Carbide Control Group without Transition Layer

[0080] A single-material YG13 cemented carbide green body with dimensions of φ18.7 mm in diameter and 9.3 mm in height was prepared by additive manufacturing. The molding parameters corresponded to the YG13 substrate printing parameters used in Example 1. The debinding, vacuum sintering, and high-temperature and high-pressure processes and parameters were consistent with those in Example 1. After vacuum sintering, the radial dimensions shrank by 17.03% and the axial dimensions shrank by 19.22%, achieving a density exceeding 98%. High-temperature and high-pressure treatment produced a polycrystalline diamond compact with a YG13 substrate. After high-temperature and high-pressure treatment, the compact exhibited a wear ratio of 39.4 × 10⁴ and an impact toughness of 893 J.

[0081] Comparative Example 2 - Diamond and carbide raw materials mixed as transition layer, no structure

[0082] Step 1

[0083] Diamond micropowder, YG13 cemented carbide powder; average diamond particle size is 10μm, average YG13 particle size is 1.2~1.6μm, density is 14.2g / cm 3; Diamond micropowder and YG13 cemented carbide powder were weighed and mixed in volume ratios of 2:3, 1:1, and 3:2 to prepare diamond-YG13 mixed powder.

[0084] Step 2

[0085] The organic polymer was prepared in a mass ratio of PW:MW:EO:EVA:HDPE:DOP:SA = 47:9:5:15:16:5:3; the volume ratio of organic polymer:diamond-YG13 mixed powder was 45:55. PW, MW, EO, EVA, HDPE, and DOP were added to an internal mixer in descending order of melting point and heated and mixed until uniform. SA was added simultaneously with the powder in 3-5 batches. During this time, the powder was cooled to allow for thorough shearing and kneading of the organic polymer to ensure uniform mixing. The cooled internal mixer was then crushed and sieved to obtain the desired feed granules. The internal mixing temperature was 145°C, and the cooling temperature-time was 125°C-30 minutes, for a total internal mixing time of 1.5 hours.

[0086] Step 3

[0087] A high-impact toughness transition layer and PDC substrate model was designed and fabricated in an integrated manner. The model consists of two components: a YG13 substrate and a diamond-YG13 mixed powder transition layer, from bottom to top. The model dimensions are φ18.7 × 9.3 mm, with the YG13 substrate measuring φ18.7 × 8.2 mm and the diamond-YG13 transition layer measuring φ18.7 × 1.1 mm.

[0088] The designed integrated high-impact toughness transition layer and PDC substrate model was imported into the corresponding slicing software and extrusion printer at a 1:1 ratio. Two extruders were assigned to the upper and lower layers, and the corresponding printing strategy parameters were set in the software: nozzle size 0.4mm, layer thickness 0.15mm, extrusion temperature 165°C, fill flow rate 90%, print platform temperature 80°C, fill speed 30mm / s, trace width 0.4mm, single-layer trace mode straight, and upper layer trace direction [0, 90°]. The prepared YG13 and diamond-10Co materials were then fed into the two hoppers of the extrusion 3D printer and printed according to the preset parameters.

[0089] The subsequent degreasing, vacuum sintering, and high-temperature and high-pressure sintering steps and parameters were consistent with those described in Example 1. The resulting transition layer-carbide substrate green body had a regular morphology, a dimensional deviation of less than 3%, a green body relative density of 98%, and no bubbling or cracking defects during solvent degreasing. After vacuum sintering, the radial dimensions of the YG13 substrate shrank by 17.13%, the radial dimensions of the transition layer shrank by 16.9%, and the axial dimensions of the sample shrank by 18.45%. The diamond surface was partially graphitized. After high temperature and high pressure, the graphite and diamond dissolved and precipitated to form polycrystalline diamond. After high temperature and high pressure, the PDC wear ratio was 39.3×10 4 、37.6×10 4 、38.2×10 4 , the impact toughness is 985J, 1075J, and 963J.

Claims

1. A PDC substrate with a high impact toughness structural transition layer, characterized by: The invention comprises a cemented carbide substrate, a transition layer, and a PCD layer; the cemented carbide substrate is composed of cemented carbide, the transition layer is composed of N sub-transition layers, and any one of the sub-transition layers contains a diamond region and a cemented carbide region; wherein the cemented carbide content in the diamond region is less than the cemented carbide content in the cemented carbide region, and the diamond content in the diamond region is greater than the diamond content in the cemented carbide region; The PDC substrate containing a high impact toughness structural transition layer includes at least one of the following schemes 1 or 2; Solution 1: Project perpendicularly to any sub-transition layer. In the projected sub-transition layer, the carbide area forms a mesh line, the mesh line forms a grid, and the diamond filler is filled in the grid; the grids in adjacent sub-transition layers are offset; Option 2: Any sub-transition layer is composed of alternating cemented carbide rings and diamond rings, the cemented carbide rings and diamond rings are in a concentric circle structure, and the diamond content in the cemented carbide rings is less than that in the diamond rings; In solution 1, the total thickness of the diamond area is greater than or equal to 0.1 mm. In solution 1, the number of sub-transition layers is greater than or equal to 3. In the first solution, the width of the cemented carbide grid line is less than 1.2 mm; the diamond content in the cemented carbide grid line is less than the diamond content in the diamond filler; In scheme 1, the offset is 1 / 8 to 2 / 3 of the area of ​​the smallest grid, and the offset angle is 15 to 45°; In the second scheme, the carbide rings and / or diamond rings in adjacent sub-transition layers are offset; the offset is 1 / 5-2 / 3 of the thickness of the diamond ring, that is, the thickness of any carbide ring increases and occupies 1 / 5-2 / 3 of the thickness of the diamond ring.

2. The PDC substrate with a high impact toughness structural transition layer according to claim 1, characterized in that: The total thickness of the transition layer is 0.2~3mm.

3. The PDC substrate with a high impact toughness structural transition layer according to claim 1, characterized in that: The total thickness of the transition layer is 0.5~2mm.

4. The PDC substrate with a high impact toughness structural transition layer according to claim 1, characterized in that: In Option 1 and Option 2, a hard alloy layer is distributed between adjacent sub-transition layers.

5. The PDC substrate with a high impact toughness structural transition layer according to claim 1, characterized in that: The cemented carbide substrate is composed of WC-Co cemented carbide; the cemented carbide used in the transition layer includes WC-Co cemented carbide; The WC-Co cemented carbide has a Co content of 5-25 wt.%; the diamond powder is mixed with one or both of Co and WC, with a content of 0-30 vol.%.

6. A method for preparing an integrated PDC substrate containing a high impact toughness structural transition layer; characterized in that: The steps include: 1) Diamond feed preparation: Diamond powder is mixed with one or more of Co powder and WC powder at a content of 0-40 vol.% to prepare M powder. Diamond feed is prepared by mixing an organic polymer binder and M powder as raw materials through mixing and granulation. The M powder and organic polymer binder are mechanically mixed in advance to obtain a uniform mixture, with a raw material d90 < 50 microns and a mass ratio of 70-95:5-30. The powder loading of M powder + organic polymer binder is 45-65 vol.%. M powder is a diamond mixed powder. When the diamond mixed powder contains only diamond powder, it is also called M powder. 2) Cemented carbide feedstock preparation: Prepare cemented carbide powder. The cemented carbide is WC-Co, where the mass fraction of Co is 5-25wt.%, and the mass fraction of WC is 75-95wt.%. The cemented carbide feedstock is made from organic polymer and cemented carbide powder by mixing, kneading, and granulating. When manufacturing the cemented carbide feedstock, the powder loading is 45-65vol.%, taking into account its molding bonding with the diamond feedstock during the printing stage and its shrinkage matching during the debinding and sintering stage. The organic polymer comprises a filler, a skeleton, a plasticizer, and a surfactant, with a mass ratio of 55-75:20-40:2-5:1-5 respectively; the filler comprises one or more of solid paraffin wax PW, liquid paraffin LPW, and microcrystalline wax MW; the skeleton comprises one or more of vegetable oil EO, high-density polyethylene HDPE, low-density polyethylene LDPE, polypropylene PP, and ethylene-vinyl acetate copolymer EVA; the plasticizer is selected from at least one of dioctyl phthalate DOP, dibutyl phthalate DBP, tricresyl phosphate TCP, and tributyl citrate TBC; and the surfactant is selected from at least one of stearic acid SA and oleic acid; 3) 2D structure construction: Model the target 3D structure and convert the 3D structure into A multi-layer two-dimensional structure diagram that can be recognized by the printing device; 4) Printing Preparation: Place the diamond feedstock and carbide feedstock prepared in steps 1) and 2) into different hoppers of the extrusion 3D printer. Select the nozzle size and print layer thickness based on the target structural accuracy, set the printing strategy parameters, and import the modeling slice file. 5) Extrusion printing: According to the set structure and path, the nozzle size is 0.1-0.8mm, the layer thickness is 0.1-0.2mm, the extrusion temperature is 120-180℃, the fill flow rate is 50-100%, the printing platform temperature is 70-100℃, the fill speed is 10-40mm / s, the trace width is consistent with the nozzle diameter, the single layer trace mode is straight, and the upper layer trace direction is [0, 90°]. Extrusion molding is performed to obtain the printed blank; 6) Degreasing and sintering: After degreasing, the printed blank is sintered by first vacuuming and then filling with protective gas to obtain a PDC substrate with a high impact toughness structural transition layer; the sintering temperature is 1400-1500°C.

7. The method for integrated preparation of a PDC substrate containing a high impact toughness structural transition layer according to claim 6, characterized in that: In step 1), the mass ratio of M powder to organic polymer binder is 80-90:10-20; the powder loading amount of M powder + organic polymer binder is 48-57 vol.%; In step 2), the powder loading amount is 50~61vol.%; The filler is a mixture of PW and MW, the skeleton is a mixture of HDPE and EVA, the plasticizer is DOP, and the surfactant is SA.

8. The method for integrated preparation of a PDC substrate containing a high impact toughness structural transition layer according to claim 6, characterized in that: When the model consists of a carbide substrate and a transition layer from bottom to top, during the printing process, the nozzle with carbide feed placed in the extrusion printer is first started according to the preset parameters to prepare the carbide substrate; then the double nozzles are operated in an orderly manner according to the model design to prepare each sub-transition layer on the carbide substrate, the sub-transition layer is composed of alternately stacked diamond layers and carbide layers, and the area hot-pressed and composited with diamond is the diamond layer, thus obtaining a high impact toughness structure transition layer-carbide substrate green body; the alternately stacked In the transition layer, the cemented carbide layer is sandwiched between the diamond layers, and the diamond layer is penetrated by the cemented carbide feed in a grid-like structure, and the cemented carbide grids in adjacent diamond layers are staggered. In the high impact toughness structure transition layer-cemented carbide substrate green body, the total thickness of the transition layer is 0.2-3 mm. In the transition layer, the thickness of a single diamond layer is not less than 0.1 mm, the number of layers is not less than 3, and the thickness of the cemented carbide layer is 0.1-1 mm. In the single diamond layer, the width of the cemented carbide grid line is less than 1.2 mm.

9. The method for integrated preparation of a PDC substrate containing a high impact toughness structural transition layer according to claim 6, characterized in that: Degreasing includes solvent degreasing, wherein n-heptane is used as a degreasing solvent, and degreasing is performed at 30-60° C. for 12-36 hours to obtain a degreased composite green body; After solvent degreasing, thermal degreasing and vacuum sintering are carried out; specifically, the composite green body after solvent degreasing is placed in a vacuum furnace for thermal degreasing, and the temperature is slowly raised to 550°C in an H2 atmosphere furnace with a flow rate of 40~60L / min, and kept warm for 40~90min to completely remove the organic polymer binder; then, the temperature is continuously raised to 1400~1500°C in a vacuum state, and 3~6bar high-pressure argon gas is introduced and kept warm for 20~50min, and then the sample is cooled in the furnace to obtain a PDC substrate with a high impact toughness structural transition layer.

10. An application of a PDC substrate containing a high impact toughness structural transition layer according to any one of claims 1 to 5, characterized in that it comprises: The obtained PDC substrate sintered body of the high-impact toughness structural transition layer and diamond micropowder are assembled into a high-temperature and high-pressure synthesis block in a manner that the transition layer and the diamond micropowder are in contact, and placed in a hexahedral press for high-temperature and high-pressure synthesis; the synthesis process is pressure: 5-7.5GPa, temperature: 1400-1700℃.

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