An assembly structure of a polycrystalline diamond synthetic block

Abstract

The present invention discloses an assembly structure of a polycrystalline diamond synthetic block, comprising a cylindrical synthetic column, a carbon tube arranged outside the circumference of the synthetic column, a conductive steel ring arranged at both ends of the carbon tube, and a pyrophyllite block wrapping the carbon tube and the conductive steel ring; dolomite sheets are arranged at both ends of the synthetic column, and the dolomite sheets are embedded in the two ends of the inner side of the carbon tube; a titanium belt wrapping the synthetic column is arranged between the synthetic column and the carbon tube; titanium sheets are fitted at both ends of the outer side of the carbon tube, and the titanium sheet is conductively connected to the conductive steel ring, the conductive steel ring is an inverted bowl-shaped structure, and is filled with dolomite powder pressed material; the end of the titanium belt is in contact with and conductive to the titanium sheet; a composite insulating tube is coated on the carbon tube. The assembly structure of the polycrystalline diamond synthetic block adds a metal supercharging component, and the shape of the metal supercharging component is adjusted to compensate for the imbalance of the pressure field, improve the controllability of the pressure field, reduce the pressure required for synthesis, reduce press loss, and extend the life of the top hammer.

Description

Technical Field

[0001] The invention relates to the technical field of polycrystalline diamond synthesis, in particular to an assembly structure of a polycrystalline diamond synthesis block. Background Art

[0002] Polycrystalline diamond synthesis requires a specific high-temperature, high-pressure environment. Achieving a balanced, stable high-temperature, high-pressure environment requires strict control of temperature and pressure accuracy; mechanical stability of the high-pressure equipment; chemical stability of the insulation and pressure-transmitting materials; precise assembly dimensions of the synthesized blocks; and reliable processes. Currently, domestic polycrystalline diamond synthesis equipment mostly uses small-bore, six-sided presses with cylinder diameters of 650mm or 750mm. Due to the limitations of the synthesis chamber and process, the yield rate of each synthesized block is relatively low. To address the issue of low production, major manufacturers in the industry use the seed method or seed-coated nickel-based catalyst materials, and then adjust the synthesis process to promote nucleation during the synthesis process, thereby increasing the yield rate of polycrystalline diamond. If a large-cavity six-sided top press with a cylinder diameter of 850mm or above is used to synthesize polycrystalline diamond, the required pressure and temperature are higher, which causes great damage to the equipment. In addition, during the growth process of polycrystalline diamond, the pressure fluctuation and uneven pressure distribution cause the quality of polycrystalline diamond to drop significantly. In addition, high pressure leads to the formation of polycrystals around the synthesis column. The uneven pressure easily causes the generated polycrystalline diamond to have pores, impurity doping, and small particles. Even if the yield rate is improved, the quality is reduced, and the final result is not worth the loss. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the existing defects, provide an assembly structure of a polycrystalline diamond synthetic block, add a metal booster component, adjust the shape of the metal booster component, compensate for the imbalance of the pressure field, improve the controllability of the pressure field, and reduce the pressure required for synthesis, reduce press losses, and extend the life of the top hammer, which can effectively solve the problems in the background technology.

[0004] To achieve the above objectives, the present invention provides the following technical solutions: an assembly structure of a polycrystalline diamond synthetic block, comprising a cylindrical synthetic column, carbon tubes disposed outside the circumference of the synthetic column, conductive steel rings disposed at both ends of the carbon tubes, and a pyrophyllite block encapsulating the carbon tubes and the conductive steel rings;

[0005] Dolomite sheets are provided at both ends of the synthetic column, and the dolomite sheets are embedded at both ends of the inner side of the carbon tube;

[0006] A titanium belt wrapping the synthetic column is provided between the synthetic column and the carbon tube;

[0007] Titanium sheets are fitted at both ends of the outer side of the carbon tube, and the titanium sheets are electrically connected to the conductive steel ring. The conductive steel ring is an inverted bowl-shaped structure filled with dolomite powder pressed material.

[0008] The end of the titanium strip is in contact and conductive with the titanium sheet;

[0009] The carbon tube outer sheath composite insulating tube;

[0010] The composite insulating tube is covered with a dolomite tube, and the dolomite tube is covered with a special-shaped iron ring; the cross-section of the special-shaped iron ring is circular inside and square outside, and the corners are provided with arc chamfers;

[0011] The conductive steel ring is covered with a pyrophyllite ring, and the outer circumferential surface of the pyrophyllite ring is the same as the axial projection of the special-shaped iron ring;

[0012] The pyrophyllite ring and the special-shaped iron ring are used together to cover the pyrophyllite blocks, and the pyrophyllite blocks are coaxially arranged in two groups, upper and lower.

[0013] As a preferred technical solution of the present invention, the synthesis column includes a catalyst and graphite. The catalyst uses 7:3 nickel-iron alloy powder with a particle size between 120-230 meshes, and the graphite uses high-purity flaky graphite with a particle size range between 200-500 meshes.

[0014] As a preferred technical solution of the present invention, the composite insulating tube is a mixture of NaCl and ZrO2 with a mixing ratio of 3.5:1.5-4.5:0.5.

[0015] A polycrystalline diamond synthesis method based on the above-mentioned assembly structure; a synthetic column is prepared by mixing a catalyst and graphite in a mass ratio of 1:5-1:3 in a three-dimensional mixer for 10-15 hours; granulation is performed using an isostatic press at a granulation pressure of 10-20 MPa; and a four-column press is used to press the reaction core into a columnar shape;

[0016] Synthetic block assembly structure assembly;

[0017] Pre-treatment of the synthetic block, insulation in a nitrogen-filled insulation box at 120°C for 1-2 hours;

[0018] The synthetic blocks are pressed and the pressure is slowly increased to 60-85Mpa in a six-sided top press with a power of 1300-1450W.

[0019] Compared with the existing technology, the present invention has the following advantages: the assembly structure of the polycrystalline diamond synthetic block adopts a 0.1-0.5mm thick titanium strip, combined with titanium sheets at the upper and lower ends, to form a closed space, which solves the problem of high brittleness and easy cracking of traditional carbon tubes and effectively prevents the entry of impurities. At the same time, the titanium metal performs the functions of electrical and thermal conductivity, making the internal and external temperature fields more balanced;

[0020] Composite insulation tube 5 with NaCl and ZrO2 in a ratio of 3.5:1.5-4.5:0.5 on the carbon tube outer shell. NaCl has good thermal insulation and pressure transmission properties, but under high temperature and high pressure, it will spontaneously nucleate and crystallize, reducing the thermal insulation performance. Therefore, doping ZrO2 reduces temperature loss and improves the stability of the cavity;

[0021] Dolomite has a large thermal expansion coefficient, and its performance changes little under high temperature and high pressure. It has good pressure transmission effect, but poor thermal insulation performance, so it is used as the inner lining pipe;

[0022] The dolomite tube is covered with a special-shaped iron ring with an inner circle and an outer convex shape. During the synthesis of polycrystalline diamond, the pressure distribution is high on the four sides of the pyrophyllite block and low on the four corners of the pyrophyllite block. Using the iron ring as a pressure-boosting block can significantly reduce the pressure required for synthesis, from the original 95MPa to 85MPa. The pressure increase is mainly related to the thickness of the iron ring. The thicker the iron ring, the more obvious the pressure increase. In order to compensate for the pressure difference between the four corners and the four sides of the pyrophyllite, the iron ring is set to a special-shaped structure. The thickness of the iron ring is 1mm on the four sides, and the thickness of the iron ring at the four corners gradually increases to 2-3mm. The iron ring at the four corners of the pyrophyllite is 1-2mm thicker than that at the four sides of the pyrophyllite, which can make the pressure more balanced.

[0023] Pyrophyllite blocks have good creep properties in the early stage, and hysteresis occurs during the pressure increase and pressure reduction process, which plays a sealing role. However, under high temperature and high pressure, a phase change occurs, and the layered structure gradually disappears, and the thermal insulation, sealing, and pressure transmission performance deteriorate. Therefore, a dolomite inner liner is placed inside to improve its sealing and pressure transmission performance.

[0024] At the same time, the pyrophyllite block adopts a structure that is divided into two parts by a cross-section, which reduces the uneven thickness of the pyrophyllite block caused by the flow sealing of the pyrophyllite during the press synthesis;

[0025] During the pretreatment of the synthetic block, nitrogen is used for heat preservation to prevent secondary oxidation or moisture absorption by the outside air;

[0026] By selecting the thickness of the iron ring, choosing the appropriate pressure and temperature, the synthetic block can be pressed under low pressure and low temperature environment, ensuring that the polycrystalline diamond in the press is always in a stable and balanced state, and effectively reducing press losses;

[0027] Moreover, after the pressure is balanced, the conversion rate and yield rate are effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the structure of the present invention;

[0029] Figure 2 A top view of a pyrophyllite block according to the present invention;

[0030] Figure 3 This is a top view of the special-shaped iron ring of the present invention;

[0031] Figure 4 A top view of a pyrophyllite ring according to the present invention;

[0032] Figure 5 This is an enlarged view of point A of the present invention;

[0033] Figure 6 The pressure field distribution inside and outside the special-shaped iron ring and talc block.

[0034] In the figure: 1. Pyrophyllite block; 2. Special-shaped iron ring; 3. Pyrophyllite ring; 4. Dolomite tube; 5. Composite insulation tube; 6. Carbon tube; 7. Titanium strip; 8. Conductive steel ring; 9. Filling material; 10. Titanium sheet; 11. Dolomite sheet. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] See also Figures 1-6 The present invention provides a technical solution: an assembly structure of a polycrystalline diamond synthetic block, comprising a cylindrical synthetic column, a carbon tube 6 arranged outside the circumference of the synthetic column, a conductive steel ring 8 arranged at both ends of the carbon tube 6, and a pyrophyllite block 1 wrapping the carbon tube 6 and the conductive steel ring 8;

[0037] Dolomite sheets 11 are provided at both ends of the synthetic column, and the dolomite sheets 11 are embedded in both ends of the inner side of the carbon tube 6;

[0038] A titanium belt 7 wrapping the synthetic column is provided between the synthetic column and the carbon tube 6;

[0039] Titanium sheets 10 are fitted on both ends of the outer side of the carbon tube 6. The titanium sheets 10 are electrically connected to the conductive steel ring 8. The conductive steel ring 8 is an inverted bowl-shaped structure filled with dolomite powder pressed material.

[0040] The end of the titanium strip 7 is in contact with the titanium sheet 10;

[0041] The carbon tube 6 is sheathed with a composite insulating tube 5;

[0042] The composite insulating tube 5 is covered with the dolomite tube 4, and the dolomite tube 4 is covered with the special-shaped iron ring 2; the cross section of the special-shaped iron ring 2 is circular inside and square outside, and the corners are provided with arc chamfers;

[0043] The conductive steel ring 8 is covered with a pyrophyllite ring 3, and the outer circumference of the pyrophyllite ring 3 is the same as the axial projection of the special-shaped iron ring 2;

[0044] The pyrophyllite ring 3 and the special-shaped iron ring 2 are used together to cover the pyrophyllite block 1, and the pyrophyllite block 1 is coaxially arranged in two groups, upper and lower.

[0045] The synthetic column includes a catalyst and graphite. The catalyst uses 7:3 nickel-iron alloy powder with a particle size between 120-230 meshes. The graphite uses high-purity flake graphite with a particle size range between 200-500 meshes.

[0046] The composite insulating tube 5 is a mixture of NaCl and ZrO2, with a mixing ratio of 3.5:1.5-4.5:0.5.

[0047] Also disclosed is a polycrystalline diamond synthesis method based on the above assembly structure;

[0048] To make the synthetic column, the catalyst and graphite with a mass ratio of 1:5-1:3 are mixed in a three-dimensional mixer for 10-15 hours; granulated in an isostatic press with a granulation pressure of 10-20 MPa; and pressed into a columnar reaction core using a four-column press.

[0049] Synthetic block assembly structure assembly;

[0050] Pre-treatment of the synthetic block, insulation in a nitrogen-filled insulation box at 120°C for 1-2 hours;

[0051] The synthetic blocks are pressed and the pressure is slowly increased to 60-85Mpa in a six-sided top press with a power of 1300-1450W.

[0052] When making assemblies,

[0053] A 0.2mm thick titanium strip 7 is used, combined with 0.8mm titanium sheets 10 at the upper and lower ends, to form a closed space. It replaces the carbon tubes 6 for electrical and thermal conductivity, and is combined with dolomite sheets 11 for insulation and heat preservation.

[0054] At the same time, the top conductive steel ring 8 adopts an inverted bowl-shaped structure, with the bowl wall part in contact with the titanium sheet 10. The bowl wall thickness is small, which reduces heat loss. In addition, the dolomite powder pressed material in the conductive steel ring 8 serves as the filling material 9. Under high temperature and high pressure, it has the same force conduction performance and thermal insulation performance, thereby further reducing the transmission of the internal temperature of the synthetic column to the top hammer.

[0055] The carbon tube 6 is coated with a composite insulating tube 5 made of a composite material of NaCl and ZrO2 with a ratio of 3.5:1.5;

[0056] The assembled synthetic block is placed in a nitrogen-filled insulation oven at 120°C for 1.5 hours, then placed in a top press, where it is slowly pressurized at 60-85Mpa and synthesized at a power of 1300-1450W. After slowly releasing the pressure, a column core is obtained. The column core is processed and purified to obtain polycrystalline diamond particles, with the yield increased from the original 120 carats / block to 500 carats / block.

[0057] in,

[0058] During the synthesis process of polycrystalline diamond, the pressure distribution is high on the four sides of pyrophyllite and low at the four corners of pyrophyllite. Using an iron ring as a pressure booster can significantly reduce the synthesis pressure from the original 95MPa to 85MPa. The pressure boost is mainly related to the thickness of the iron ring. The thicker the iron ring, the more obvious the pressure boost. In order to make up for the pressure difference between the four corners and the four sides of pyrophyllite, the iron ring is set to a special-shaped structure. The thickness of the special-shaped iron ring 2 is 1mm on the four sides, and the thickness of the iron ring at the four corners gradually increases to 2-3mm. The iron ring at the four corners of pyrophyllite is 1-2mm thicker than that at the four sides of pyrophyllite, which can make the pressure more balanced.

[0059] The use of special-shaped iron rings as metal boosters balances the pressure inside the synthesis column, effectively improving the conversion rate and increasing the yield by about 30%. The combination of pyrophyllite blocks 1 and dolomite tubes 4 effectively improves the thermal insulation performance, making the internal temperature balanced, and increasing the particle size concentration rate and yield rate of the product by about 10%.

[0060] At the same time, the new synthetic column assembly structure effectively reduces the pressure required for the synthesis of polycrystalline diamonds. The holding pressure can be reduced from 95MPa to about 85MPa, a reduction of about 10%, further reducing energy consumption and equipment loss. Moreover, the reduced synthesis pressure reduces the pressure change inside the column core, and the internal pressure field tends to be stable, thereby reducing power, further reducing press losses, extending the life of the top hammer, and saving energy consumption and costs.

[0061] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An assembly structure of a polycrystalline diamond synthetic block, comprising a cylindrical synthetic column, a carbon tube (6) arranged outside the circumference of the synthetic column, a conductive steel ring (8) arranged at both ends of the carbon tube (6), and a pyrophyllite block (1) wrapping the carbon tube (6) and the conductive steel ring (8), characterized in that: Dolomite sheets (11) are provided at both ends of the synthetic column, and the dolomite sheets (11) are embedded in the two ends of the inner side of the carbon tube (6); a titanium strip (7) is provided between the synthetic column and the carbon tube (6) to wrap the synthetic column; titanium sheets (10) are provided at both ends of the outer side of the carbon tube (6), and the titanium sheet (10) is conductive with the conductive steel ring (8), and the conductive steel ring (8) is an inverted bowl-shaped structure filled with dolomite powder pressed material; the end of the titanium strip (7) is in contact with the titanium sheet (10) and conductive; the carbon tube (6) is covered with a composite insulating tube (5); the composite insulating tube (5) is covered with a dolomite tube (4), and the dolomite tube (4) is covered with a special-shaped iron ring (2); the cross-section of the special-shaped iron ring (2) is an inner circle and an outer square, and the corners are provided with arc chamfers; The conductive steel ring (8) is covered with a pyrophyllite ring (3), and the outer circumference of the pyrophyllite ring (3) is the same as the axial projection of the special-shaped iron ring (2); the pyrophyllite ring (3) and the special-shaped iron ring (2) are jointly covered with a pyrophyllite block (1), and the pyrophyllite block (1) is arranged coaxially in two groups. In order to compensate for the pressure difference between the four corners and the four sides of the pyrophyllite, the iron ring is set to a special-shaped structure. The thickness of the special-shaped iron ring (2) is 1mm at the four sides, and the thickness of the iron ring at the four corners gradually increases to 2-3mm.

2. The assembly structure of the polycrystalline diamond synthetic block according to claim 1, characterized in that: The synthetic column includes a catalyst and graphite. The catalyst is nickel-iron alloy powder with a ratio of 7:3 and a particle size of 120-230 meshes. The graphite is high-purity flake graphite with a particle size range of 200-500 meshes.

3. The assembly structure of the polycrystalline diamond synthetic block according to claim 1, characterized in that: The composite insulating tube (5) is a mixture of NaCl and ZrO2, with a mixing ratio of 3.5:1.5-4.5:0.

5.

4. A method for synthesizing polycrystalline diamond based on the assembly structure of claim 1, characterized in that: To make the synthetic column, the catalyst and graphite with a mass ratio of 1:5-1:3 are mixed in a three-dimensional mixer for 10-15 hours; granulation is carried out using an isostatic press with a granulation pressure of 10-20 MPa; a four-column press is used to press the columnar reaction core; the synthetic block assembly structure is assembled; the synthetic block is pretreated and kept warm in a nitrogen-protected insulation box at 120°C for 1-2 hours; the synthetic block is pressed by slowly increasing the pressure to 60-85 MPa in a six-sided top press and synthesizing at a power of 1300-1450W.

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