Big diamond single crystal blank plastic assembly block and plastic growth method

Abstract

The invention provides a blank molding assembly block of diamond large single crystals and a plastic growth method, and belongs to the technical field of superhard material synthesis. The blank molding assembly block comprises a mutually-embedded metal catalyst layer formed by mutually embedding a plurality of prismatic table metal catalyst structures, the whole mutually-embedded metal catalyst layer is in a prismatic table shape, one of the upper end face and the lower end face of each prismatic table metal catalyst structure is in contact with the high-purity graphite carbon source layer, and the other one of the upper end face and the lower end face of each prismatic table metal catalyst structure is in contact with the seed crystal; the adjacent prismatic table metal catalyst structures are separated by an insulating layer, and the insulating layer is a Ca coating or a BN coating. A mutually-embedded prismatic-table-shaped metal catalyst structure with an axial temperature gradient and a carbon diffusion channel is constructed in a blank assembly block, diamond is induced to grow in a preset direction in an HPHT environment, directional shaping growth of the diamond is achieved under the condition that the process complexity is not improved, and the quality of the diamond is improved. The crystal morphology controllability, the catalytic agent utilization efficiency and the final drilling rate are remarkably improved, and the single-cavity yield is increased.

Description

Technical Field

[0001] This invention belongs to the field of superhard material synthesis technology, specifically relating to a blank plastic assembly block for large diamond single crystals and a plastic growth method. Background Technology

[0002] Currently, the mainstream methods for growing diamond can be divided into chemical vapor deposition (CVD) and high-temperature, high-pressure (HPHT) methods. HPHT can induce rapid rearrangement and crystallization of carbon atoms under conditions of approximately 5–6 GPa and 1500℃, resulting in grown diamonds with fewer defects and better crystal integrity. Therefore, the continuous development of new HPHT diamond growing technologies is of great significance.

[0003] Current HPHT (High Temperature High Pressure) diamond cultivation technology still faces some bottlenecks. For example, Chinese patent application CN119753807A discloses a plastic assembly block for high temperature and high pressure diamond cultivation. By setting a plastic cavity with an inverted frustum in the crystal bed, the diamond is induced to grow into a bipyramidal structure, which allows for the cutting of two bare diamonds, increasing the utilization rate of the blank from about 33% to 50-70%. From this patent application, it can be seen that the pyrophyllite block has a side length of 84 mm, a through-hole size of 60 mm, and a crystal bed / catalyst diameter of 50 mm. To achieve a bipyramidal diamond growth structure, the upper diameter of the crystal bed is preferably 10 mm, with a height of 5–7 mm, and the seed hole depth is 1 mm. Therefore, the actual thickness of the crystal bed will reach 6–8 mm. The thickness of the metal catalyst used for diamond growth is 10 mm. The weight of the grown diamond blank is concentrated between 3 and 4.5 ct. Given the bipyramidal shape of the diamond, it is easy to calculate that the height of the diamond blank is approximately 7 mm. Due to its symmetrical structure, the single-pyramidal diamond blank in the catalyst is approximately 3.5 mm. From the above data, it can be seen that approximately 6.5 mm of the metal catalyst in the cavity does not participate in diamond growth, meaning that over 60% of the catalyst material is wasted. Furthermore, based on the data analysis in the aforementioned patent application, 10 diamonds can be grown simultaneously. With 160 hours of growth, the total mass of diamonds in a single cavity is approximately 33.2–35.2 ct. With a catalyst thickness of 50 mm, an upper diameter of 10 mm for the crystal bed, and ideally, up to 19 diamonds can be grown, resulting in a total mass of approximately 60 ct in a single cavity. The diamond yield (ct) is significantly lower than the industry average of around 80 ct for single-cavity diamonds. In summary, although the method disclosed in the aforementioned patent application increases the diamond yield from 33% to 50-70%, the resulting economic benefits are limited. Furthermore, because the crystal bed is made of ceramic and the catalyst is made of metal, their thermal conductivity differs, leading to different temperatures within the plastic cavity. This inevitably results in different processes for growing bipyramidal diamonds in the crystal bed and catalyst. Additionally, since the upper catalyst lacks a plastic cavity, its pyramidal shape depends on the growth process; these issues increase the difficulty of controlling the diamond growth process.

[0004] Therefore, it is necessary to develop a new method that can increase single-cavity production, improve drill yield, and reduce catalyst waste and process difficulty. Summary of the Invention

[0005] In view of this, based on the design of irregularly shaped catalyst structures, a blank molding assembly block for large single diamond crystals and a plastic growth method are provided. According to the fundamental principle that diamond can only grow in metal catalysts, an interlocking frustum-shaped metal catalyst structure with axial temperature gradients and carbon diffusion channels is constructed in the blank assembly block. Diamond is then induced to grow along a predetermined direction in an HPHT environment. Without increasing process complexity, directional plastic growth of diamond is achieved, significantly improving crystal morphology controllability, catalyst utilization efficiency, and final diamond yield, thereby increasing the yield per cavity.

[0006] Specifically, the technical solution provided by this invention is as follows: A blank molding assembly block for a large diamond single crystal includes an interlocking metal catalyst layer composed of multiple interlocking frustum metal catalyst structures. The interlocking metal catalyst layer is frustum shaped as a whole. One of the upper and lower end faces of each frustum metal catalyst structure is in contact with a high-purity graphite carbon source layer, and the other is in contact with a seed crystal. Adjacent frustum metal catalyst structures are separated by an insulating layer, which is a Ca coating or a BN coating. The frustum metal catalyst structure is composed of an Fe-Co alloy or an Fe-Ni alloy.

[0007] To further improve the quality of large single-crystal diamond blanks, the Fe-Co alloy is composed of Fe: 50-65%, Co: 30-45%, Al: 0-2%, Ti: 0-2%, Cu: 0-2%, and Mn: 0-2% by mass percentage; the Fe-Ni alloy is composed of Fe: 50-70%, Ni: 30-40%, Al: 0-2%, Ti: 0-2%, Cu: 0-2%, and Mn: 0-2%.

[0008] To further improve catalyst utilization efficiency and final drilling yield, the frustum metal catalyst structure is a quadrangular frustum structure, a hexagonal frustum structure, or an octagonal frustum structure. Preferably, the frustum metal catalyst structure is a regular frustum structure, with the side lengths of its upper and lower end faces being 0.8–1.2 mm and 7.5–8.5 mm, respectively. The height of the frustum metal catalyst structure is 5–12 mm, and the seed crystal size is 0.3–1 mm.

[0009] In one specific embodiment, the blank molding assembly block further includes a pressure transmission and sealing component, which has a plastic growth cavity, and the plastic growth cavity is stacked with the high-purity graphite carbon source layer, the intercalated metal catalyst layer, and the crystal bed on which the seed crystal is disposed.

[0010] In one specific embodiment, the pressure-transmitting sealing assembly includes a synthesis chamber, in which a dolomite tube is embedded. The dolomite tube contains an insulating material tube, a heating element, and two conductive pressure-transmitting layers. The heating element is embedded within the insulating material tube. The two conductive pressure-transmitting layers are respectively disposed at both ends of the insulating material tube and the heating element. Both ends of the heating element are provided with a thermal insulation layer, and the two thermal insulation layers form the plastic growth chamber. A central through-hole is opened at each end of the synthesis chamber, and a conductive ring is installed in each central through-hole. The conductive ring is disposed on the conductive pressure-transmitting layer.

[0011] A method for plastic growth of a large single-crystal diamond blank includes: first, placing the blank molding assembly block in a six-sided press, applying a pressure of 5.0 to 6.0 GPa, and constructing a temperature gradient from top to bottom, wherein the temperature gradient is 15 to 50°C; then heating the temperature to 1350 to 1550°C and maintaining it for 120 to 170 h to obtain a cone-shaped large single-crystal diamond blank.

[0012] To further improve the controllability of crystal morphology, catalyst utilization efficiency, final diamond yield, and the quality of large single-crystal diamond blanks, preferably, the pressure is 5.4–5.6 GPa, the temperature is 1400–1500℃, and the holding time is 120–150 h.

[0013] Compared with the prior art, the technical solution provided by the present invention has the following advantages: Significantly improved crystal morphology controllability: This invention utilizes an interlocking frustum metal catalyst structure to achieve the shaped growth of diamond in an HPHT environment. Compared to traditional sheet or powder catalysts that easily lead to irregular polyhedral crystals, this approach can induce crystals to expand directionally along a preset axis, thereby directly forming large, regular, cone-shaped single crystals. This effectively reduces the need for subsequent cutting and processing, increasing the utilization rate of diamond blanks from 33% to 50-70%.

[0014] Increased single-cavity diamond yield: This invention achieves interlocking diamond growth by adopting an interlocking frustum metal catalyst structure, which reduces the gaps between diamonds. With the cavity size remaining unchanged, the number of seed crystals can theoretically be increased by 2 times. Taking a catalyst with a diameter of 50mm as an example, the single-cavity yield can be increased from about 60-80 ct to about 100-110 ct.

[0015] Reduced process complexity: The catalysts used in this invention are of the same type, and the diamond growth regions, temperatures, pressures, and carbon dissolution rates are identical. Therefore, no changes to the process are required; high-quality diamond synthesis can be achieved within the cavity described in this invention using conventional diamond synthesis processes.

[0016] Improved catalyst utilization: This invention improves the aspect ratio of diamond by adopting an interlocking frustum metal catalyst structure; and increases the utilization rate of metal catalyst to about 60%, reducing the waste of catalyst materials. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the interlocking metal catalyst layer structure used in an embodiment of the present invention; Figure 2 This is a schematic diagram of the blank molding assembly block structure of a large diamond single crystal provided in an embodiment of the present invention; Figure 3 The adoption provided for the embodiments of the present invention Figure 2 The diagram shows the process of diamond crystals growing along the conical axis in the HPHT environment in the molded assembly block. Figure 4 The images show the actual product of the cone-shaped diamond blank synthesized in Embodiment 1 of the present invention (left) and the actual product of the cut diamond (right). Figure 5 The images show the actual diamond blank synthesized in Comparative Example 1 (left) and the actual diamond after cutting (right). The components in the above diagram are: 1. Conductive coil; 2. Thermal insulation layer; 3. Heating element; 4. Dolomite tube; 5. High-purity graphite carbon source layer; 6. Interlocking metal catalyst layer; 61. Frustum metal catalyst structure; 62. Insulation layer; 7. Seed crystal; 8. Insulation material tube; 9. Pyrophyllite block; 10. Conductive pressure transmission layer. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0019] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0020] In this invention, unless otherwise specified and / or stated, all numerical values ​​involving component amounts are "by weight". Unless otherwise specified, the terminology used in this invention are common terms in the relevant field. Unless otherwise specified, the synthesis methods, testing methods, etc., used in the various embodiments are conventional means well known to those skilled in the art, and the raw materials and equipment used are all available from publicly available commercial sources.

[0021] This invention, based on the fundamental principle that diamond can only grow in metal catalysts, designs an irregularly shaped catalyst structure. This structure enables the plastic growth of large single-crystal diamond blanks. This not only provides a novel pathway for crystal plastic growth but also lays the technological foundation for efficient and low-loss diamond fabrication, possessing excellent industrialization prospects and innovative value. Therefore, this invention provides a blank plastic assembly block for large single-crystal diamond and a plastic growth method, the specific implementation of which is as follows: Please see Figures 1-2 This invention provides a blank molding assembly block for large diamond single crystals, comprising an interlocking frustum-shaped metal catalyst layer 6, which is composed of multiple interlocking frustum-shaped metal catalyst structures 61. One end face of each frustum-shaped metal catalyst structure 61 contacts a high-purity graphite carbon source layer 5, and the other end face contacts a seed crystal 7. The frustum-shaped metal catalyst structure is made of an Fe-Co alloy or an Fe-Ni alloy. To prevent interpenetration between different frustum-shaped metal catalyst structures 61 and to improve the success rate of molding the large diamond single crystal blank, adjacent frustum-shaped metal catalyst structures 61 are separated by an insulating layer 62, which is a Ca coating or a BN coating, and the insulating layer completely covers the contact area between adjacent frustum-shaped metal catalyst structures 61.

[0022] To further improve catalyst utilization efficiency and final drilling yield, the frustum metal catalyst structure is a square frustum structure, a hexagonal frustum structure, or an octagonal frustum structure, preferably a regular frustum structure, such as a regular square frustum structure, a regular hexagonal frustum structure, or a regular octagonal frustum structure.

[0023] To further improve the aspect ratio of the diamond large single crystal blank, increase the catalyst utilization efficiency and the final drilling yield, the side lengths of the upper and lower end faces of the frustum metal catalyst structure are 0.8-1.2 mm and 7.5-8.5 mm, respectively, the height of the frustum metal catalyst structure is 5-12 mm, and the size of the seed crystal 7 is 0.3-1 mm.

[0024] The composition of the catalyst has a significant impact on the quality of large single-crystal diamond blanks. Different catalyst formulations can control the carbon transport rate. In this invention, the Fe-Co alloy, by mass percentage, is composed of Fe: 50-65%, Co: 30-45%, Al: 0-2%, Ti: 0-2%, Cu: 0-2%, and Mn: 0-2%; the Fe-Ni alloy is composed of Fe: 50-70%, Ni: 30-40%, Al: 0-2%, Ti: 0-2%, Cu: 0-2%, and Mn: 0-2%. Preferably, the frustum-shaped metal catalyst structure 61 is composed of Fe... 60 Co 40 Fe 59 Co 39Ti1Cu1, Fe 58 Co 38 Ti2Cu2, Fe 60 Ni 40 Fe 60 Ni 38 Al1Mn1, Fe 58 Ni 39 It is composed of Ti2Mn1, etc. The frustum metal catalyst structure 61 in the interlocking metal catalyst layer 6 adopts the same type of catalyst.

[0025] The other structures in the blank molding assembly block of the large diamond single crystal are all existing technologies. The main purpose of this invention is to include the interlocking metal catalyst layer 6 in the blank molding assembly block. The pressure transmission and sealing assembly includes a synthesis cavity, in which a dolomite tube is embedded. The dolomite tube contains an insulating material tube, a heating tube, and two conductive pressure transmission layers. The heating tube is embedded in the insulating material tube. The two conductive pressure transmission layers are respectively disposed at both ends of the insulating material tube and the heating tube. Both ends of the heating tube are provided with heat insulation layers. A plastic growth cavity is formed between the two heat insulation layers. The high-purity graphite carbon source layer, the interlocking metal catalyst layer, and the crystal bed with the seed crystal are stacked in the plastic growth cavity. A central through hole is opened at both ends of the synthesis cavity. A conductive ring is installed in each central through hole. The conductive ring is disposed on the conductive pressure transmission layer.

[0026] Specifically, in one particular implementation, such as Figure 2 As shown, the press cylinder diameter used for large diamond single crystal synthesis is 800 mm. The blank molding assembly block includes: a pyrophyllite block 9 with a size of 84 mm and a central through hole of 60 mm, with a conductive ring 1 installed at the central through hole; a 2 mm thick dolomite tube 4 embedded in the pyrophyllite block 9, the total height of the embedded dolomite tube 4 is 60 mm, the crystal bed height is 3 mm, and the dolomite tube 4 is provided with an insulating material tube 8, a heating tube 3, and two conductive pressure transmission layers 10. Both ends of the heating tube 3 are provided with heat insulation layers 2, and the plastic growth cavity is formed between the two heat insulation layers 2; the plastic growth cavity is stacked with the high-purity graphite carbon source layer 5, the interlocking metal catalyst layer 6, and the crystal bed with the seed crystal 7; after the blank molding assembly block is assembled, it is placed in a forced-air drying oven at 100-120℃ for 30-60 minutes to remove adsorbed water, and it is ready for use.

[0027] This invention also provides a method for the plastic growth of a large single-crystal diamond blank, comprising: first, placing the blank plastic assembly block in a six-sided press, applying a pressure of 5.0–6.0 GPa, and establishing a top-down temperature gradient of 15–50 °C; then heating the temperature to 1350–1550 °C and maintaining it for 120–170 h, under this environment, such as Figure 3 As shown, carbon atoms in the high-purity graphite carbon source layer 5 preferentially diffuse along the axial direction of the frustum-shaped metal catalyst structure 61, inducing the diamond crystal in the seed crystal 7 to grow along a predetermined direction, thereby obtaining a cone-shaped diamond large single crystal blank. Preferably, the pressure is 5.4–5.6 GPa, the temperature gradient is 15–35 °C, the temperature is 1400–1500 °C, and the holding time is 120–150 h; this can further improve the controllability of crystal morphology, catalyst utilization efficiency, final diamond yield, and the quality of the diamond large single crystal blank.

[0028] The technical solution to be protected by this invention will be further explained through specific embodiments below. Example 1 This embodiment provides a blank molding assembly block for a large single diamond crystal, the structure of which is as follows: Figures 1-2 As shown, the frustum-shaped metal catalyst structure 61 in this embodiment is made of Fe 59 Co 39 The Ti1Cu1-composed regular square frustum structure has side lengths of 1 mm and 8 mm on the upper and lower end faces, respectively, and a height of 6 mm. That is, the height of the interlocking metal catalyst layer 6 is 6 mm and the maximum diameter is 50 mm. In addition, 32 seed crystals 7 with a diameter of about 0.8 mm are placed on the crystal bed along with the frustum metal catalyst structure 61.

[0029] This embodiment also provides a method for plastically growing diamond large single crystal blanks using the above-mentioned blank molding assembly block, comprising: first, placing the above-mentioned blank molding assembly block in a hinged six-sided press with a cylinder diameter of 800mm, applying a pressure of 5.5 GPa (hydraulic pressure 80MPa), and constructing a temperature gradient from top to bottom, wherein the temperature gradient is 20-30℃; then heating the temperature to 1480℃ (power 9.76kw) and maintaining it for 120 h; after synthesis, removing it, and treating it with nitric acid to obtain diamond large single crystal blanks; among them, one crystal failed to grow, and a total of 31 diamond large single crystal blanks were actually obtained, the blanks are conical, the weight of a single crystal is between 2.86 and 4.13 ct, the total weight is 103.68 ct, and the aspect ratio is between 0.60 and 1.35; taking one of them Figure 4 The blank shown on the left, measuring 3.27ct, was cut to obtain... Figure 4 (Right) shows a loose diamond with a clarity of VS, color of E, and a weight of 2.07 ct; the utilization rate of the large single-crystal diamond blank is 63.2%. The catalyst utilization rate in this embodiment is 50.3% (calculated based on a diamond density of 3.5 g / cm³). 3 The total weight is 103.68 × 0.2 = 20.736 g, therefore the volume is 5.92 cm³. 3According to the volume formula, the volume of a catalyst column with a diameter of 50 mm and a height of 6 mm is easily obtained as 11.78 cm³. 3 Therefore, the catalyst utilization rate was 50.3%.

[0030] Example 2 This embodiment provides a blank molding assembly block for a large single diamond crystal, the structure of which is as follows: Figures 1-2 As shown, the frustum-shaped metal catalyst structure 61 in this embodiment is made of Fe 58 Co 38 The hexagonal frustum structure composed of Ti2Cu2 has side lengths of 0.8 mm and 7.5 mm at the top and bottom end faces, respectively, and a height of 6 mm. That is, the height of the interlocking metal catalyst layer 6 is 6 mm and the maximum diameter is 50 mm. Furthermore, 35 seed crystals 7 with a diameter of about 0.5 mm are placed on the crystal bed along with the frustum metal catalyst structure 61.

[0031] This embodiment also provides a method for plastically growing diamond large single crystal blanks using the above-mentioned blank molding assembly block, comprising: first, placing the above-mentioned blank molding assembly block in a hinged six-sided press with a cylinder diameter of 800 mm, applying a pressure of 5.0 GPa (hydraulic pressure 75 MPa), and constructing a temperature gradient from top to bottom, wherein the temperature gradient is 15-20℃; then heating the temperature to 1400℃ (power 9.0 kW) and maintaining it for 167 h; after synthesis, removing it, and treating it with nitric acid to obtain diamond large single crystal blanks; a total of 35 diamond large single crystal blanks were actually obtained, the blanks are conical, the weight of a single crystal is between 2.82 and 3.56 ct, the total weight is 112.7 ct, and the aspect ratio is between 0.71 and 1.47; taking one blank with a weight of 2.95 ct, cutting it to obtain a clarity of VS, a color of E, and a weight of 1.81 The diamond used was a bare diamond; the utilization rate of the large single-crystal diamond blank was 61.35%. The catalyst utilization rate in this embodiment was 54.6%.

[0032] Example 3 This embodiment provides a blank molding assembly block for a large single diamond crystal, the structure of which is as follows: Figures 1-2 As shown, the frustum-shaped metal catalyst structure 61 in this embodiment is made of Fe 58 Co 38 The octagonal frustum structure composed of Mn1Ti1Cu2 has side lengths of 0.8 mm and 7.5 mm at the top and bottom end faces, respectively, and a height of 6.5 mm. That is, the height of the interlocking metal catalyst layer 6 is 6.5 mm and the maximum diameter is 50 mm. In addition, 35 seed crystals 7 with a diameter of about 0.5 mm are placed on the crystal bed along with the frustum metal catalyst structure 61.

[0033] This embodiment also provides a method for plastically growing diamond large single crystal blanks using the above-mentioned blank molding assembly block, comprising: first, placing the above-mentioned blank molding assembly block in a hinged six-sided press with a cylinder diameter of 800 mm, applying a pressure of 5.0 GPa (hydraulic pressure 75 MPa), and constructing a temperature gradient from top to bottom, wherein the temperature gradient is 20-35℃; then heating the temperature to 1400℃ (power 9.0 kW) and maintaining it for 156 h; after synthesis, removing it, and treating it with nitric acid to obtain diamond large single crystal blanks; a total of 35 diamond large single crystal blanks were actually obtained, the blanks are conical, the weight of a single crystal is between 2.93 and 3.56 ct, the total weight is 117.25 ct, and the aspect ratio is between 0.74 and 1.39; taking one blank with a weight of 3.36 ct, cutting it to obtain a clarity of VS, a color of E, and a weight of 2.08. The diamond used was a bare diamond; the utilization rate of the large single-crystal diamond blank was 61.9%. The catalyst utilization rate in this embodiment was 52.19%.

[0034] Comparative Example 1 This comparative example provides a method for growing large single-crystal diamond blanks, which is basically the same as the growth method provided in Example 1, the main difference being that: this comparative example uses conventional Fe... 59 Co 39 Ti1Cu1 rod-shaped metal catalyst replaces the frustum-shaped metal catalyst structure 61 in Example 1, resulting in a 6 mm high metal catalyst layer. Thus, 25 seed crystals 7 with a diameter of 0.8 mm are placed on the crystal bed. All other methods are the same, ultimately yielding 24 blanks with a hexahedral shape, each weighing between 2.23 and 4.85 ct, for a total weight of 75.6 ct, and with an aspect ratio between 0.34 and 0.82. The best quality blank is selected from these. Figure 5 (Left) A 3.42ct blank, after being cut, yields the following: Figure 5 The loose diamond shown on the right, with a clarity of VS, color of E, and a weight of 1.17ct, has a utilization rate of 34.2%. The catalyst utilization rate in this comparative example is 36.41%.

[0035] Therefore, by employing an interlocking frustum metal catalyst structure, the present invention enables the plastic growth of diamond in an HPHT environment. Compared with traditional sheet or powder catalysts, which are prone to causing irregular polyhedral crystals, the method provided by the present invention can induce the crystal to expand directionally along a preset axis, thereby directly forming a large, regular, cone-shaped single crystal, effectively reducing the need for subsequent cutting and processing, and increasing the utilization rate of diamond blanks from 33% to 50-70%.

[0036] Furthermore, the embodiments of the present invention employ an interlocking frustum metal catalyst structure to achieve interlocking growth of diamonds, reducing the gaps between diamonds. With the cavity size remaining unchanged, the number of seed crystals can theoretically be increased by up to 2 times. The embodiments show that, taking a catalyst with a diameter of 50 mm as an example, the yield per cavity can be increased from about 60-80 ct to about 100-120 ct.

[0037] Furthermore, the embodiments of the present invention employ an interlocking frustum metal catalyst structure, which improves the aspect ratio of the diamond single crystal; compared with the catalyst layer with a general height of about 6 mm, the utilization rate of the catalyst is increased to about 60%, reducing the waste of catalyst materials.

[0038] Therefore, the method provided in this embodiment of the invention uses the same type of catalyst, and the diamond single crystal growth region, temperature and pressure, and carbon dissolution rate are the same. There is no need to change the process. High-quality diamond synthesis can be achieved in the cavity described in this invention by using conventional diamond synthesis process. The synthesis process is simple.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A blank molding assembly block for large single diamond crystals, characterized in that, The material includes an interlocking metal catalyst layer composed of multiple interlocking frustum metal catalyst structures. The interlocking metal catalyst layer is frustum shaped as a whole. One of the upper and lower end faces of each frustum metal catalyst structure is in contact with a high-purity graphite carbon source layer, and the other is in contact with a seed crystal. Adjacent frustum metal catalyst structures are separated by an insulating layer, which is a Ca coating or a BN coating. The frustum metal catalyst structure is made of Fe-Co alloy or Fe-Ni alloy.

2. The blank molding assembly block according to claim 1, characterized in that, The Fe-Co alloy, by mass percentage, is composed of Fe: 50-65%, Co: 30-45%, Al: 0-2%, Ti: 0-2%, Cu: 0-2%, and Mn: 0-2%.

3. The blank molding assembly block according to claim 1, characterized in that, The Fe-Ni alloy is composed of Fe: 50-70%, Ni: 30-40%, Al: 0-2%, Ti: 0-2%, Cu: 0-2%, and Mn: 0-2%.

4. The blank molding assembly block according to claim 1, characterized in that, The frustum-shaped metal catalyst structure is made of Fe 60 Co 40 Fe 59 Co 39 Ti1Cu1, Fe 58 Co 38 Ti2Cu2, Fe 60 Ni 40 Fe 60 Ni 38 Al1Mn1 or Fe 58 Ni 39 Composition: Ti2Mn1.

5. The blank molding assembly block according to claim 1, characterized in that, The frustum metal catalyst structure is a four-sided frustum structure, a six-sided frustum structure, or an octagonal frustum structure.

6. The blank molding assembly block according to claim 5, characterized in that, The frustum metal catalyst structure is a regular frustum structure, with the side lengths of its upper and lower end faces being 0.8–1.2 mm and 7.5–8.5 mm, respectively. The height of the frustum metal catalyst structure is 5–12 mm, and the seed crystal size is 0.3–1 mm.

7. The blank molding assembly block according to claim 6, characterized in that, It also includes a pressure-transmitting sealing assembly, which has a plastic growth chamber, in which the high-purity graphite carbon source layer, the intercalated metal catalyst layer, and the crystal bed with the seed crystal are stacked.

8. The blank molding assembly block according to claim 7, characterized in that, The pressure-transmitting sealing assembly includes a synthesis chamber, in which a dolomite tube is embedded. The dolomite tube contains an insulating material tube, a heating tube, and two conductive pressure-transmitting layers. The heating tube is embedded in the insulating material tube. The two conductive pressure-transmitting layers are respectively disposed at both ends of the insulating material tube and the heating tube. Both ends of the heating tube are provided with a thermal insulation layer. The two thermal insulation layers form the plastic growth chamber. A central through hole is opened at each end of the synthesis chamber. A conductive ring is installed in each central through hole. The conductive ring is disposed on the conductive pressure-transmitting layer.

9. A method for the plastic growth of a large single-crystal diamond blank, comprising: First, the blank molding assembly block according to any one of claims 1 to 8 is placed in a six-sided top press, a pressure of 5.0 to 6.0 GPa is applied, and a temperature gradient from top to bottom is constructed, wherein the temperature gradient is 15 to 50°C; then the temperature is heated to 1350 to 1550°C and maintained for 120 to 170 h to obtain a cone-shaped diamond large single crystal blank.

10. The plastic growth method according to claim 9, characterized in that, The pressure is 5.4–5.6 GPa, the temperature is 1400–1500℃, and the duration is 120–150 h.

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