Polycrystalline diamond compact and preparation method thereof

Abstract

The invention relates to a polycrystalline diamond compact and a preparation method thereof, and belongs to the field of preparation of polycrystalline diamond compacts. The polycrystalline diamond compact is composed of a hard alloy matrix layer and a polycrystalline diamond layer, the hard alloy matrix layer is made of tungsten carbide and Co and Ni adhesives, and the usage amount of Co and the usage amount of Ni account for 8.5%-10% and 1.5%-3% of the mass of the hard alloy matrix layer respectively; tungsten carbide raw materials for preparing the hard alloy matrix layer are composed of, by volume fraction, 10%-15% of coarse particle size tungsten carbide, 75%-80% of medium particle size tungsten carbide and 5%-10% of fine particle size tungsten carbide, the coarse particle size ranges from 10 micrometers to 15 micrometers, the medium particle size ranges from 2 micrometers to 8 micrometers, and the fine particle size is smaller than 1 micrometer. Co and Ni are used as adhesives of the hard alloy matrix layer, the use amount of Co and Ni is controlled, and distribution of the particle size of tungsten carbide is combined, so that the polycrystalline diamond compact has chemical corrosion resistance and wear resistance at the same time.

Description

Technical Field

[0001] The invention relates to a polycrystalline diamond composite sheet and a preparation method thereof, and belongs to the field of preparation of polycrystalline diamond composite sheets. Background Art

[0002] Polycrystalline diamond composite sheet is a new functional material composed of a cemented carbide matrix layer and a polycrystalline diamond layer. Since the polycrystalline diamond layer has extremely high wear resistance and high hardness, and the cemented carbide matrix has high impact resistance and weldability, it is widely used in oil drilling, geological drilling and coal mining.

[0003] Although polycrystalline diamond composite sheets combine the advantages of polycrystalline diamond layers and cemented carbide substrates, the rock formations during drilling are complex, and the impact strength and wear resistance of polycrystalline diamond composite sheets are limited. When encountering particularly hard rock formations, such as pebble layers, the diamond polycrystalline layer will quickly collapse and fail, and the remaining cemented carbide substrate will also fail.

[0004] The Chinese invention patent with the authorization announcement date of March 2, 2016 and the authorization announcement number of CN103072332B discloses a polycrystalline diamond composite sheet, which includes a cemented carbide matrix layer and a polycrystalline diamond layer, the polycrystalline diamond layer includes a wear-resistant area composed of cobalt-poor polycrystalline diamond particles and an impact-resistant area composed of cobalt-rich polycrystalline diamond, and the cobalt-poor polycrystalline diamond particles are dispersed in the impact-resistant area. Although the polycrystalline diamond sheet with this special structure shows good wear resistance and impact resistance, it requires that the cobalt-poor polycrystalline diamond particles be dispersed in the impact-resistant area and control the volume ratio of the wear-resistant area to the impact-resistant area to be 1 to 2, and the overall preparation method is very strict.

[0005] At the same time, the wear resistance mentioned above for the polycrystalline diamond composite sheet only avoids large-scale polycrystalline diamond breakage, rather than reducing the degree of wear, and cannot truly improve the wear resistance of the polycrystalline diamond composite sheet. Furthermore, in the drilling environment, the polycrystalline diamond composite sheet is easily corroded by the mixed system of rock cuttings, worn-off diamond cuttings and mud, thereby causing structural defects in the polycrystalline diamond composite sheet and affecting the overall performance. At present, the existing polycrystalline diamond composite sheet cannot take into account both chemical corrosion resistance and wear resistance at the same time. Summary of the invention

[0006] The first object of the present invention is to provide a polycrystalline diamond compact to solve the problem that the polycrystalline diamond compact in the prior art cannot take into account both chemical corrosion resistance and wear resistance.

[0007] The second object of the present invention is to provide a method for preparing a polycrystalline diamond compact to solve the problem that the method for preparing a high-performance polycrystalline diamond compact in the prior art has strict requirements.

[0008] To achieve the above object, the first technical solution of the present invention is as follows:

[0009] A polycrystalline diamond compact, wherein the cemented carbide substrate layer is made of tungsten carbide, Co, and Ni binders. The amount of Co is 8.5% - 10% of the mass of the cemented carbide substrate layer, and the amount of Ni is 1.5% - 3% of the mass of the cemented carbide substrate layer;

[0010] The tungsten carbide raw material for preparing the cemented carbide substrate layer consists of coarse-grained tungsten carbide, medium-grained tungsten carbide, and fine-grained tungsten carbide. Calculated based on a total volume fraction of 100%, the volume fraction of the coarse-grained tungsten carbide is 10% - 15%, the volume fraction of the medium-grained tungsten carbide is 75% - 80%, and the volume fraction of the fine-grained tungsten carbide is 5 - 10%; the coarse grain size is 10 - 15 μm, the medium grain size is 2 - 8 μm, and the fine grain size is less than 1 μm.

[0011] The polycrystalline diamond compact of the present invention is an exploratory invention. By using Co and Ni as binders for the cemented carbide substrate layer and controlling the amounts of Co and Ni, combined with the distribution of the tungsten carbide particle size, while ensuring that the polycrystalline diamond compact has basic chemical corrosion resistance, its wear resistance is improved.

[0012] Further preferably, the volume fraction of the coarse-grained tungsten carbide is 10% - 12%, the volume fraction of the medium-grained tungsten carbide is 78% - 80%, and the volume fraction of the fine-grained tungsten carbide is 10%.

[0013] Preferably, the amount of Co is 9.5 - 10% of the mass of the cemented carbide substrate layer, and the amount of Ni is 1.5 - 1.7% of the mass of the cemented carbide substrate layer. When preparing the cemented carbide substrate layer with Co and Ni in these amounts, the resulting polycrystalline diamond compact has better chemical corrosion resistance and wear resistance.

[0014] To ensure the hardness of the polycrystalline diamond compact, preferably, the polycrystalline diamond layer is made of diamond micropowder and a binder. The binder consists of Co and W. The amount of Co is 5% - 8% of the mass of the polycrystalline diamond layer, and the amount of W is 1.5% - 2% of the mass of the polycrystalline diamond layer.

[0015] Preferably, the diamond micropowder is composed of coarse-grained diamond particles and fine-grained diamond particles. Based on a total volume fraction of 100%, the volume fraction of the coarse-grained diamond particles is 75% - 80%, and the volume fraction of the fine-grained diamond particles is 20% - 25%. The coarse grain size is 15 - 25 μm, and the fine grain size is 1 - 8 μm. Further preferably, the volume fraction of the coarse-grained diamond particles is 75% - 77%, and the volume fraction of the fine-grained diamond particles is 23% - 25%.

[0016] The second technical solution of the present invention is as follows:

[0017] A method for preparing a polycrystalline diamond composite sheet, comprising the following steps: mixing tungsten carbide with Co and Ni binders, pressing and gradient sintering to obtain a cemented carbide matrix layer; assembling the cemented carbide matrix layer and the raw materials of the polycrystalline diamond layer and then performing high-temperature and high-pressure sintering to obtain the polycrystalline diamond composite sheet.

[0018] The present invention makes the polycrystalline diamond composite sheet have both chemical corrosion resistance and wear resistance by controlling the binder composition and the tungsten carbide particle size distribution of the cemented carbide matrix layer. Its specific preparation method is relatively simple, and the preparation of the polycrystalline diamond composite sheet can be achieved without strict process requirements, which is convenient for large-scale production and utilization.

[0019] To ensure the denseness of the cemented carbide matrix layer, preferably, the gradient sintering includes a first heating stage and a second heating stage; the final temperature of the first heating stage is 1000 - 1050 °C, and the holding time is 45 - 50 s; the final temperature of the second heating stage is 1380 - 1400 °C, and the holding time is 3950 - 4000 s.

[0020] To ensure the quality of the polycrystalline diamond composite sheet, preferably, the pressure of the high-temperature and high-pressure sintering is 7.7 - 8 Gpa, and the pressure holding time is 880 - 900 s.

[0021] Preferably, the temperature of the high-temperature and high-pressure sintering is 1500 - 1550 °C, and the sintering time is 350 - 400 s. Description of the Drawings

[0022] Figure 1 It is the morphology diagram of the cemented carbide matrix of Example 1 of the present invention under a scanning electron microscope;

[0023] Figure 2 It is the morphology diagram of the cemented carbide matrix of Example 2 of the present invention under a scanning electron microscope;

[0024] Figure 3 It is the chemical corrosion result diagram of the polycrystalline diamond composite sheet of Example 1 of the present invention;

[0025] Figure 4 Chemical etching result diagram of the polycrystalline diamond composite sheet of Embodiment 2 of the present invention;

[0026] Figure 5 Distribution diagram of the uniform sintered body between each diamond particle and the binder particle in the polycrystalline diamond layer of Embodiment 1 of the present invention;

[0027] Figure 6 Distribution diagram of the uniform sintered body between each diamond particle and the binder particle in the polycrystalline diamond layer of Embodiment 2 of the present invention;

[0028] Figure 7 Relationship diagram between the grinding layer number and the grinding mouth area of the polycrystalline diamond composite sheets of Embodiments 1 and 2 of the present invention;

[0029] Figure 8 Grinding mouth condition diagram of the polycrystalline diamond composite sheet of Embodiment 1 of the present invention;

[0030] Figure 9 Grinding mouth condition diagram of the polycrystalline diamond composite sheet of Embodiment 2 of the present invention. Specific embodiments

[0031] The technical solutions of the present invention will be further described below in conjunction with specific embodiments. In the following examples, unless otherwise specified, the raw materials involved are commercially available conventional raw materials, and the treatment means involved are conventional treatment means.

[0032] I. Specific embodiments of the polycrystalline diamond composite sheet and its preparation method of the present invention are as follows:

[0033] Embodiment 1

[0034] The polycrystalline diamond composite sheet of this embodiment is composed of a cemented carbide substrate layer and a polycrystalline diamond layer. Among them, the cemented carbide substrate layer is made of the following raw materials by mass fraction: 88.5% tungsten carbide, 10% Co (particle size 0.2 - 0.5 μm), 1.5% Ni (0.5 μm < particle size < 1.0 μm); by volume fraction, the particle size distribution of tungsten carbide is: 10% of 10 - 15 μm coarse particle size tungsten carbide, 80% of 2 - 8 μm medium particle size tungsten carbide, and 10% of 0.5 - 1 μm fine particle size tungsten carbide.

[0035] The polycrystalline diamond layer is made of the following raw materials by mass fraction: 5% Co (particle size 0.2 - 0.5 μm), 1.5% W (particle size 0.2 - 1.0 μm), and the balance is diamond micropowder; by volume fraction, the diamond micropowder is composed of 75% of 15 - 25 μm coarse particle size diamond particles and 25% of 1 - 8 μm fine particle size diamond particles.

[0036] The preparation method of the polycrystalline diamond composite sheet of this embodiment adopts the following steps:

[0037] (1) Mix the raw materials in the cemented carbide matrix layer of this example evenly and press them. Then, heat up for 500 s to 1000 °C, keep the temperature for 50 s, heat up for 1000 s to 1380 °C, and after keeping the temperature for 4000 s, cool it in the furnace to room temperature. The morphology diagram of the prepared cemented carbide matrix is as shown in Figure 1 shown;

[0038] (2) Mix the raw materials of the polycrystalline diamond layer evenly, place them in a metal cup, seal them after assembling with the cemented carbide matrix, and perform high-temperature and high-pressure synthesis and sintering through a six-sided top press. Increase the pressure to 7.7 GPa in the cavity in 100 s and keep the pressure for 900 s; Sintering temperature: Heat up for 300 s to 1500 °C, keep the temperature for 400 s, and cool down slowly for 200 s (cool down to 800 °C in 100 s, reduce to 100 °C in 60 s, and reduce to room temperature in 40 s) to obtain a polycrystalline diamond composite sheet.

[0039] Example 2

[0040] The polycrystalline diamond composite sheet of this example is composed of a cemented carbide matrix layer and a polycrystalline diamond layer. Among them, the cemented carbide matrix layer is made of the following raw materials by mass fraction: 88.5% tungsten carbide, 8.5% Co (particle size 0.2 - 0.5 μm), 3% Ni (0.5 μm < particle size < 1.0 μm); By volume fraction, the particle size distribution of tungsten carbide is: 10% of 10 - 15 μm coarse-grained tungsten carbide, 80% of 2 - 8 μm medium-grained tungsten carbide, and 10% of 0.5 - 1 μm fine-grained tungsten carbide.

[0041] The polycrystalline diamond layer is made of the following raw materials by mass fraction: 5% Co (particle size 0.2 - 0.5 μm), 1.5% W (particle size 0.2 - 1.0 μm), and the balance is diamond micropowder; By volume fraction, the diamond micropowder is composed of 75% of 15 - 25 μm coarse-grained diamond particles and 25% of 1 - 8 μm fine-grained diamond particles.

[0042] The preparation method of the polycrystalline diamond composite sheet of this example adopts the following steps:

[0043] (1) Mix the substances in the cemented carbide matrix layer of this example evenly and press them. Then, heat up for 500 s to 1000 °C, keep the temperature for 50 s, heat up for 1000 s to 1380 °C, and after keeping the temperature for 4000 s, cool it in the furnace to room temperature. The morphology diagram of the prepared cemented carbide matrix is as shown in Figure 2 shown;

[0044] (2) Mix the raw materials of the polycrystalline diamond layer evenly, place them in a metal cup, assemble them with the cemented carbide substrate and seal them. Then, perform high-temperature and high-pressure synthesis and sintering through a six-sided top press. Raise the pressure to 7.7 GPa in the cavity within 100 s and hold the pressure for 900 s. Sintering temperature: Raise the temperature to 1500 °C within 300 s, keep the temperature for 400 s, and cool down slowly for 200 s (cool down to 800 °C within 100 s, reduce to 100 °C within 60 s, and reduce to room temperature within 40 s) to obtain the polycrystalline diamond composite sheet.

[0045] II. Comparative Example

[0046] The polycrystalline diamond composite sheet of this comparative example is only different from that of Example 1 in that the cemented carbide substrate layer is made of raw materials with the following mass fractions: 88.5% tungsten carbide and 11.5% Co (particle size 0.2 - 0.5 μm); the particle size distribution of tungsten carbide is the same as that of Example 1. The specific preparation method is the same as that of Example 1.

[0047] The polycrystalline diamond composite sheets of the above Examples 1 - 2 and the comparative example are made into the same specifications, with a diameter of 15.88 mm, a total height of 13.2 mm, and a height of the polycrystalline diamond layer of 3.0 mm.

[0048] III. Experimental Example

[0049] Experimental Example 1 Chemical Corrosion Resistance Test

[0050] Perform chemical corrosion resistance tests on the polycrystalline diamond composite sheets of each example and the comparative example. Specifically, immerse the polycrystalline diamond composite sheets in a 5% mass fraction of NaCl neutral solution for 480 h (immerse the entire cemented carbide composite sheet in the NaCl solution), and observe the corrosion product situation around its outer periphery. The corrosion results of the polycrystalline diamond composite sheet of Example 1 are as Figure 3 shown, and the corrosion results of the polycrystalline diamond composite sheet of Example 2 are as Figure 4 shown.

[0051] According to Figure 3 , Figure 4 comparison, it can be seen that when the total content of Co and Ni remains constant, further increasing the Ni content in Example 2 can, to a certain extent, inhibit the abnormal growth of WC grains and improve its chemical corrosion resistance. The surface corrosion of Example 1 is relatively serious, with obvious surface potholes, meeting the basic chemical corrosion resistance requirements.

[0052] Experimental Example 2 Evaluation of the Particle Distribution Uniformity of the Polycrystalline Diamond Layer

[0053] After surface polishing the polycrystalline diamond layers of Examples 1 - 2, observe the morphology and perform energy spectrum measurement under a scanning electron microscope (SEM) to obtain the results as Figure 5 , Figure 6 shown.

[0054] According to Figure 5 and Figure 6 comparison, it can be seen that the distribution of the metal binder (the white substance in the figure is Co) in the polycrystalline diamond layer of Example 1 is more uniform, and the C-C bond combination is better, which is beneficial to the improvement of the impact performance.

[0055] Wear resistance test of Experimental Example 3

[0056] Wear resistance measurement method: The polycrystalline diamond composite sheets of each example and comparative example were installed in a vertical turret lathe (VTL) and used to machine rod-shaped granite. The polycrystalline diamond composite sheet was inclined at an angle of 15° with respect to the surface of the rod-shaped granite, the cutting depth was 0.25 mm / layer, the polycrystalline diamond composite sheet was fixed, the rod-shaped granite rotated at a certain speed, and the transverse feed rate was 2 mm / rpm. The grinding mouth area was recorded every 10 layers of grinding, and the grinding was stopped when reaching 60 layers. The grinding mouth data are shown in Table 1 below.

[0057] Table 1 Grinding mouth areas of each example and comparative example (unit: mm 2 )

[0058] Sample 10 layers 20 layers 30 layers 40 layers 50 layers 60 layers Example 1 1.673 3.376 5.009 6.363 7.377 8.504 Example 2 2.180 4.315 6.071 7.358 8.535 9.551 Comparative example / / / / / 10.233

[0059] The comparison of the grinding mouth areas of Examples 1 and 2 is as Figure 7 shown. According to Figure 7 it can be seen that when the polycrystalline diamond composite sheet of Example 1 grinds off the same thickness of granite, the grinding area is smaller, and the corresponding grinding mouth condition of the product is as Figure 8 shown. The grinding mouth condition of the polycrystalline diamond composite sheet of Example 2 under the same conditions is as Figure 9 shown. The wear resistance of Example 1 is better than that of Example 2.

[0060] Based on the above experiments, it can be seen that the polycrystalline diamond composite sheets of each example have good chemical corrosion resistance and wear resistance. Among them, the chemical corrosion resistances of Examples 1 and 2 can both meet the requirements, and the polycrystalline diamond composite sheet of Example 1 shows better wear resistance.

Claims

1. A polycrystalline diamond compact, which is composed of a cemented carbide substrate layer and a polycrystalline diamond layer, and is characterized in that, The cemented carbide matrix layer is made of tungsten carbide and Co and Ni binders. The dosage of Co is 8.5% - 10% of the mass of the cemented carbide matrix layer, and the dosage of Ni is 1.5% - 3% of the mass of the cemented carbide matrix layer; The tungsten carbide raw material for preparing the cemented carbide matrix layer consists of coarse-grained tungsten carbide, medium-grained tungsten carbide and fine-grained tungsten carbide. Calculated based on the total volume fraction of 100%, the volume fraction of the coarse-grained tungsten carbide is 10% - 15%, the volume fraction of the medium-grained tungsten carbide is 75% - 80%, and the volume fraction of the fine-grained tungsten carbide is 5 - 10%; The coarse grain size is 10 - 15μm, the medium grain size is 2 - 8μm, and the fine grain size is less than 1μm.

2. The polycrystalline diamond compact according to claim 1, wherein, The dosage of Co is 9.5 - 10% of the mass of the cemented carbide matrix layer, and the dosage of Ni is 1.5 - 1.7% of the mass of the cemented carbide matrix layer.

3. The polycrystalline diamond compact according to claim 1, wherein The polycrystalline diamond layer is made of diamond micropowder and a binder. The binder consists of Co and W. The dosage of Co is 5% - 8% of the mass of the polycrystalline diamond layer, and the dosage of W is 1.5% - 2% of the mass of the polycrystalline diamond layer.

4. The polycrystalline diamond compact according to claim 3, wherein, The diamond micropowder consists of coarse-grained diamond particles and fine-grained diamond particles. Calculated based on the total volume fraction of 100%, the volume fraction of the coarse-grained diamond particles is 75% - 80%, the volume fraction of the fine-grained diamond particles is 20% - 25%, the coarse grain size is 15 - 25μm, and the fine grain size is 1 - 8μm.

5. A method for preparing a polycrystalline diamond compact according to any one of claims 1-4, characterized in that, It includes the following steps: Mix, press and gradient sinter tungsten carbide with Co and Ni binders to obtain a cemented carbide matrix layer; Assemble the cemented carbide matrix layer and the polycrystalline diamond layer raw materials and then carry out high-temperature and high-pressure sintering to obtain a polycrystalline diamond composite sheet.

6. The preparation method of the polycrystalline diamond composite sheet according to claim 5, wherein, The gradient sintering includes a first heating stage and a second heating stage; The final temperature of the first heating stage is 1000 - 1050°C, and the holding time is 45 - 50s; The final temperature of the second heating stage is 1380 - 1400°C, and the holding time is 3950 - 4000s.

7. The preparation method of the polycrystalline diamond compact according to claim 5, wherein, The pressure of the high-temperature and high-pressure sintering is 7.7 - 8Gpa, and the pressure holding time is 880 - 900s.

8. The method for preparing a polycrystalline diamond compact according to claim 5 or 7, characterized in that, The temperature of the high-temperature and high-pressure sintering is 1500 - 1550°C, and the sintering time is 350 - 400s.

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