Large-cavity diamond cultivation method, heating device and composite heating block

Abstract

The invention relates to a large-cavity diamond cultivation method, a heating device and a composite heating block, and relates to the technical field of HTHP temperature difference method artificial diamond cultivation, and the large-cavity diamond cultivation heating device comprises a main heating pipe, a ceramic partition pipe and an auxiliary heating pipe which are sequentially arranged from inside to outside in a sleeving mode; the heating value of the auxiliary heating pipe is lower than that of the main heating pipe, the auxiliary heating pipe and the main heating pipe are combined to heat the base material, a temperature locking protection layer is formed when the auxiliary heating pipe works, it can be guaranteed that the yield of diamonds is increased, meanwhile, it is further guaranteed that the temperature field in the heating device is evenly distributed, and the quality of the diamonds is improved.

Description

Technical Field

[0001] The present application relates to the technical field of artificially grown diamonds using the HTHP temperature difference method, and in particular to a large cavity diamond growing method, a heating device and a composite heating block. Background Art

[0002] With the large-scale development of high-temperature and high-pressure equipment, the synthetic chamber of cultured diamonds is getting larger and larger. All companies are pursuing higher output and more stable quality. However, after the equipment is large-scaled, it is not possible to produce stable and high-quality products by simply enlarging the size.

[0003] High temperature and high pressure diamond cultivation is a complex growth process, which requires extreme conditions of constant high temperature and constant high pressure. In the prior art, diamonds are cultivated by placing a composite heating block in a six-sided top press. The composite heating block provides a high temperature environment for diamond cultivation. The composite heating block mainly includes a tubular heating device and a sealing structure assembled on the periphery of the tubular heating device. The inner cavity of the tubular heating device is the reaction core used for diamond cultivation. Currently, the more stable reaction core has a maximum diameter of 50 mm.

[0004] When this size is exceeded, diamond growth becomes uneven inside and outside, with large differences in grade and size, making the overall output value of large-cavity cultured diamonds even lower than that of small-cavity cultured diamonds. This is because when the diameter of the tubular structure becomes larger, most of the heat generated dissipates outward and cannot be continuously transferred into the cavity, resulting in an extremely uneven internal temperature field.

[0005] In order to optimize the internal temperature field of the heating device, CN 205988735U discloses "A nonlinear composite heating block structure", which further adds a thermal insulation structure outside the heating device to reduce heat dissipation to the outside.

[0006] However, the effect of setting up a heat preservation structure on reducing the dissipation of heat is not obvious. In order to ensure the heat preservation effect of the heat preservation structure, the thickness of the heat preservation structure will be much greater than the thickness of the heating device. Since the cavity size of the six-sided top press is fixed, this improvement method will further reduce the diameter of the heating device. Therefore, the improvement of its internal temperature field is more due to the reduction in the size of the heating device. This method cannot achieve higher yields and loses the meaning of cultivating diamonds in a large cavity.

[0007] Based on the above situation, when only the additional device is used, a larger reaction core can be obtained, but the internal temperature field is unevenly distributed, and the quality of the cultivated diamonds is poor; when the heating device is combined with the heat preservation structure, the internal temperature field can be improved to a certain extent, but the reaction core will be greatly reduced, and the output of cultivated diamonds is low. Therefore, many companies choose to give up because the six-sided top press cannot produce products normally after being enlarged. In view of this, it is urgent to provide a heating device that can ensure that the output of diamonds is increased while ensuring the uniform distribution of its internal temperature field to improve the quality of diamonds. Summary of the invention

[0008] The purpose of the present application is to provide a large-cavity diamond cultivation method, a heating device and a composite heating block, which can ensure that the diamond yield is increased while ensuring that the internal temperature field is evenly distributed to improve the quality of the diamond.

[0009] In the first aspect, the present application provides a large-cavity cultured diamond heating device that adopts the following technical solution:

[0010] A heating device for growing diamonds in a large cavity, comprising a main heating tube, a ceramic partition tube and an auxiliary heating tube which are sequentially sleeved from the inside to the outside;

[0011] The auxiliary heating tube has a lower heating value than the main heating tube, and is combined with the main heating tube to heat the substrate. The auxiliary heating tube forms a temperature-locking protective layer when working.

[0012] Furthermore, the heating value of the auxiliary heating tube accounts for 60-80% of that of the main heating tube.

[0013] Furthermore, the resistance of the main heating tube is higher than that of the auxiliary heating tube.

[0014] Furthermore, the inner diameter of the main heating tube is set to 50-70 mm.

[0015] Furthermore, the wall thickness of the ceramic partition tube is set to 0.2-2 mm.

[0016] Furthermore, the ceramic partition tube is made of at least any one of aluminum oxide and aluminum oxide.

[0017] Furthermore, the main heating tube, the ceramic partition tube and the auxiliary heating tube are arranged with equal thickness.

[0018] Furthermore, the main heating tube, the ceramic partition tube and the auxiliary heating tube are arranged with the same length.

[0019] In a second aspect, the present application provides a composite heating block, comprising a sealing structure and the above-mentioned heating device.

[0020] In a third aspect, the present application provides a cultivation method using the above-mentioned heating device.

[0021] In summary, the present application includes at least one of the following beneficial technical effects:

[0022] 1. In the present application, the substrate is heated by a combination of a main heating tube and an auxiliary heating tube. The auxiliary heating tube can generate heat autonomously when working, thereby forming a temperature-locking protective layer located on the periphery of the main heating tube. When the periphery of the auxiliary heating tube dissipates heat outward, the temperature can be maintained only by its own heat generation. Compared with the method of adopting a traditional thermal insulation structure, the auxiliary heating tube can better reduce the heat generated by the main heating tube from dissipating outward, thereby ensuring a uniform temperature field distribution inside the heating device. At the same time, the auxiliary heating tube forms a temperature-locking protective layer faster than the traditional thermal insulation structure, thereby reducing the time required for the preheating stage when cultivating diamonds.

[0023] 2. The heating device in the present application can be well applied to large-cavity diamond cultivation technology, which can increase the diamond production by about 30%, the excellent crystal rate by about 20%, and achieve uniform effect in particle size and clarity level of the cultivated diamonds.

[0024] 3. In the present application, the main heating tube and the auxiliary heating tube are separated by a ceramic partition tube. The ceramic partition tube can withstand a high temperature of about 1400°C, does not undergo qualitative changes under high temperature conditions, and does not react with the main heating tube and the auxiliary heating tube, thereby ensuring that the main heating tube and the auxiliary heating tube can operate independently and stably. The ceramic partition tube also has good thermal insulation performance, and can cooperate with the auxiliary heating tube to make the temperature field distribution inside the heating device more uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a top view of the heating device in the present application;

[0026] Figure 2 is a cross-sectional view of the heating device in the present application;

[0027] In the figure, 1. Main heating tube; 2. Ceramic partition tube; 3. Auxiliary heating tube. DETAILED DESCRIPTION

[0028] The following will be combined with the attached Figure 1-2 The technical solution of the present application is described clearly and completely. The following embodiments are exemplary and are only used to explain the present application, and cannot be interpreted as limiting the present application. In the following description, the same symbols are used to represent the same or equivalent elements, and repeated descriptions are omitted.

[0029] In the description of the present application, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the products of the present application are conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0030] In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0031] It should be further understood that the term “and / or” used in the specification and corresponding claims of this application refers to any and all possible combinations of one or more of the listed items.

[0032] Embodiment 1:

[0033] A composite heating block comprises a heating device and a sealing structure assembled on the periphery of the heating device. Figure 1 and Figure 2 The heating device includes a main heating tube 1, a ceramic partition tube 2 and an auxiliary heating tube 3 which are sequentially arranged from the inside to the outside.

[0034] When cultivating diamonds, the substrate is placed in the main heating tube 1. The auxiliary heating tube 3 and the main heating tube 1 work together to heat the substrate, providing a high-temperature environment of about 1400°C for the substrate. Among them, the main heating tube 1 is closer to the substrate than the auxiliary heating tube 3 and plays a major heating role, while the auxiliary heating tube 3 plays an auxiliary role.

[0035] The ceramic partition tube 2 partitions the main heating tube 1 and the auxiliary heating tube 3, so that the main heating tube 1 and the auxiliary heating tube 3 can operate independently. Since the auxiliary heating tube 3 can generate heat independently, compared with the traditional method of using insulation materials to prepare an insulation structure around the main heating tube 1, the auxiliary heating tube 3 can heat up quickly during operation, forming a temperature-locking protective layer located around the main heating tube 1, thereby reducing the time required for the preheating stage when cultivating diamonds.

[0036] At the same time, the auxiliary heating tube 3 can continuously generate heat, which is sufficient to maintain the stability of the temperature-locking protective layer. The temperature-locking protective layer can effectively prevent the heating tube from dissipating too much heat to the outside. Compared with the heating device that only has the main heating tube 1, the heating device in the present application can make the temperature distribution more uniform and can further reduce the heating power of the main heating tube 1 (by about 20%).

[0037] In addition, the auxiliary heating tube 3 can further assist the main heating tube 1 in heating the substrate to compensate for the heat loss of the main heating tube 1 during operation, thereby making the temperature field in the main heating tube 1 uniformly distributed.

[0038] Furthermore, considering that during the diamond cultivation process, the high temperature environment is mainly provided by the main heating tube 1 , the heating value of the auxiliary heating tube 3 is lower than that of the main heating tube 1 , and the heating value of the auxiliary heating tube 3 accounts for 60-80% of that of the main heating tube 1 .

[0039] It should be noted that the main heating tube 1 and the auxiliary heating tube 3 in the present application both use electric heating to provide a high temperature environment for the diamond, that is, the "heating amount" refers to the heat output value of the main heating tube 1 and the auxiliary heating tube 3 at their respective powers within a period of time.

[0040] In a specific embodiment, the power of the main heating tube 1 can be adjusted, for example, the main heating tube 1 and the auxiliary heating tube 3 are operated under the same current condition, and the resistance of the main heating tube 1 is higher than that of the auxiliary heating tube 3.

[0041] In this case, the resistance of the main heating tube 1 and the auxiliary heating tube 3 can be adjusted by adjusting the size and / or material of the main heating tube 1 and the auxiliary heating tube 3. When the size of the main heating tube 1 and the auxiliary heating tube 3 is adjusted, the conductive area of ​​the main heating tube 1 can be set lower than that of the auxiliary tube; when the material of the main heating tube 1 and the auxiliary heating tube 3 is adjusted, the resistivity of the main heating tube 1 can be set higher than that of the auxiliary heating tube 3.

[0042] Furthermore, in another specific embodiment, the main heating tube 1 and the auxiliary heating tube 3 may be placed under different current and voltage conditions to ensure that the heating value of the main heating tube 1 is higher than that of the auxiliary heating tube 3 .

[0043] It should be noted that in the above case, both the main heating tube 1 and the auxiliary heating tube 3 can be made of graphite material. Graphite has good thermal stability and can withstand a high temperature of 1400°C. The resistance of graphite is easy to adjust, so as to design the calorific value of the main heating tube 1 and the auxiliary heating tube 3. In other specific embodiments, the materials of the main heating tube 1 and the auxiliary heating tube 3 can also be adaptively adjusted to ensure good thermal stability and heating performance.

[0044] Furthermore, the inner diameter of the main heating tube 1 is set to 50-70 mm, that is, the heating device has a larger reaction core. In a specific embodiment, the inner diameter of the main heating tube 1 can be set to 60 mm, and in another specific embodiment, the inner diameter of the main heating tube 1 can also be set to 50 mm or 70 mm.

[0045] This is because, since the auxiliary heating tube 3 forms a temperature-locking protective layer through self-heating, the auxiliary heating tube 3 can better reduce the heat loss of the main heating tube 1 under the condition of a smaller thickness, so that the inner diameter of the main heating tube 1 can be maintained at a larger level.

[0046] Based on this, the thickness of the main heating tube 1 and the auxiliary heating tube 3 in this application are set to a relatively low level, and the sum of the thickness of the main heating tube 1, the ceramic partition tube 2 and the auxiliary heating tube 3 is the overall thickness of the heating device. The thickness of the ceramic partition tube 2 is set to 0.2-2 mm.

[0047] In a specific embodiment, the ceramic partition tube 2 can be set to 0.2 mm to further increase the reaction core of the heating device. Considering the difficulty of processing the ceramic partition tube 2 and the limited effect of further reducing the thickness of the ceramic partition tube 2 on expanding the reaction core, in another specific embodiment, the ceramic partition tube 2 can also be set to 2 mm (the difference in thickness of the ceramic partition tube 2 between the two implementations is only 1.8 mm).

[0048] Furthermore, the main heating tube 1, the ceramic partition tube 2 and the auxiliary heating tube 3 are set to have the same thickness, so as to facilitate the processing and preparation of the heating device. The main heating tube 1, the ceramic partition tube 2 and the auxiliary heating tube 3 can be specifically set according to the size of the inner cavity of the six-sided top press. For example, in a specific embodiment, the thickness of the main heating tube 1, the ceramic partition tube 2 and the auxiliary heating tube 3 are all set to 2 mm.

[0049] In this case, the combined thickness of the ceramic partition tube 2 and the auxiliary heating tube 3 is 4 mm, that is, compared with the heating device with only the main heating tube 1, the thickness is only increased by 4 mm. That is, with a small increase in thickness, it not only ensures that the internal temperature field distribution of the heating device is uniform, but also provides a reaction core of sufficient size, thereby ensuring that the output and quality of diamonds are greatly improved.

[0050] It should be noted that the thickness of the main heating tube 1, the ceramic partition tube 2 and the auxiliary heating tube 3 can also be adjusted differently according to actual conditions (ie, different thicknesses) to ensure that the inner diameter of the main heating tube 1 (ie, the reaction core) is at a larger level.

[0051] Reference Figure 2, the main heating tube 1, the ceramic partition tube 2 and the auxiliary heating tube 3 are arranged with equal lengths to ensure that the temperature-locking protective layer formed by the auxiliary heating tube 3 can better cover the outer periphery of the main heating tube 1. At the same time, the ceramic partition tube 2 can fully fill the gap between the main heating tube 1 and the auxiliary heating tube 3. When pressure is applied to the heating device, the ceramic partition tube 2 can better position the main heating tube 1 and the auxiliary heating tube 3 while isolating the main heating tube 1 and the auxiliary heating tube 3, so as to reduce the possibility of deformation of the main heating tube 1 and the auxiliary heating tube 3 due to the pressure of the six-sided top press.

[0052] Furthermore, the ceramic partition tube 2 is made of at least one of alumina and chromium oxide. In a specific embodiment, the ceramic partition tube 2 can be made of alumina. In another specific embodiment, the ceramic partition tube 2 can also be made of chromium oxide. In other embodiments, other suitable materials can also be used to make the ceramic partition tube 2 have better insulation performance, high temperature resistance and stability.

[0053] In a high temperature environment of about 1400°C, the ceramic partition tube 2 can isolate the main heating tube 1 and the auxiliary heating tube 3, and does not react with the main heating tube 1 and the auxiliary heating tube 3, thereby ensuring that the main heating tube 1 and the auxiliary heating tube 3 operate independently and stably.

[0054] At the same time, the ceramic heating tube also has good thermal insulation performance, and can cooperate with the temperature-locking protective layer formed when the auxiliary heating tube 3 is working, further reducing the heat dissipated outward by the main heating tube 1, making the temperature field distribution inside the heating device more uniform.

[0055] It should be noted that the heat dissipated outward by the main heating tube 1 is reduced mainly by forming a temperature-locking protective layer when the auxiliary heating tube 3 is working, and the ceramic partition tube 2 only plays an auxiliary role. Based on this, the wall thickness of the heating tube can also be adjusted according to actual needs to strengthen or weaken the auxiliary role of the ceramic partition tube 2.

[0056] Embodiment 2:

[0057] The difference between this embodiment 2 and embodiment 1 is that a processing method is further provided, which is used to process and shape the above-mentioned heating device, and the processing method includes the following steps:

[0058] Obtaining resistance material to prepare a main heating tube 1 and an auxiliary heating tube 3;

[0059] In a specific embodiment, the resistance material is set to graphite, and a carbon rod with a resistivity of 30 is selected and processed into a main heating tube 1 with an outer diameter of 62 mm, an inner diameter of 60 mm, and a height of 30 mm. A carbon rod with a resistivity of 25 is selected and processed into an auxiliary heating tube 3 with an outer diameter of 66 mm, an inner diameter of 64.1 mm, and a height of 30 mm.

[0060] Obtaining insulating material to prepare a ceramic partition tube 2;

[0061] In a specific embodiment, the insulating material is set to alumina, and a 64 mm diameter alumina rod is selected to process a tubular article with an outer diameter of 62.1 mm and an inner diameter of 30 mm.

[0062] The main heating tube 1, the ceramic partition tube 2 and the auxiliary heating tube 3 are sequentially sleeved from the inside to the outside to assemble a heating device.

[0063] The use of rods facilitates mechanical processing. In other specific embodiments, suitable forms such as plates, powders, etc. may also be used.

[0064] In addition, it should be noted that the 0.1 fitting clearance between the main heating tube 1 and the ceramic partition tube 2 and the 0.1 fitting clearance between the ceramic partition tube 2 and the auxiliary heating tube 3 are tolerances, and the conventional tolerance range in this industry is 0.08 to 0.15.

[0065] Embodiment 3:

[0066] The difference between this embodiment 3 and embodiment 2 is that a large cavity diamond cultivation method is also provided, and the cultivation method uses the heating device obtained by processing in embodiment 2.

[0067] Among them, diamonds are synthesized on a six-sided top press with a cylinder diameter of 900 mm. The pressure is set to 90Mpa, the power is 6.0KW, and the synthesis time is 190h.

[0068] After processing the synthetic reaction core, 30 cultured diamond roughs were obtained, totaling 150 carats. The largest one weighed 6 carats, the smallest one was 4.5 carats, and the average weight of each diamond rough was 5 carats. 25 diamonds reached the VVS clarity level. The quality and output of diamonds have been significantly improved.

[0069] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A heating device for growing diamonds in a large cavity, characterized in that: It comprises a main heating tube (1), a ceramic partition tube (2) and an auxiliary heating tube (3) which are sequentially sleeved from the inside to the outside; The auxiliary heating tube (3) has a lower heating value than the main heating tube (1), and is combined with the main heating tube (1) to heat the substrate; the auxiliary heating tube (3) forms a temperature-locking protective layer when in operation.

2. The heating device according to claim 1, characterized in that The heat output of the auxiliary heating tube (3) accounts for 60 to 80% of that of the main heating tube (1).

3. The heating device according to claim 2, characterized in that: The resistance value of the main heating tube (1) is higher than that of the auxiliary heating tube (3).

4. The heating device according to any one of claims 1 to 3, characterized in that: The inner diameter of the main heating tube (1) is set to 50-70 mm.

5. The heating device according to claim 1, characterized in that: The wall thickness of the ceramic partition tube (2) is set to 0.2-2 mm.

6. The heating device according to claim 1 or 5, characterized in that: The ceramic partition tube (2) is made of at least one of aluminum oxide and chromium oxide.

7. The heating device according to any one of claims 1, characterized in that: The main heating tube (1), the ceramic partition tube (2) and the auxiliary heating tube (3) are arranged with equal thickness.

8. The heating device according to claim 1, characterized in that The main heating tube (1), the ceramic partition tube (2) and the auxiliary heating tube (3) are arranged with the same length.

9. A composite heating block, characterized in that: It comprises a sealing structure and the heating device according to any one of claims 1 to 8.

10. A cultivation method, characterized in that: A heating device according to any one of claims 1 to 8 is used.

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