Composite growth base station for diamond synthesis

Abstract

The invention provides a composite growth base for diamond synthesis, and belongs to the technical field of diamond preparation through a chemical vapor deposition method. The composite growth base comprises an upper molybdenum table, a middle stainless steel table, a lower molybdenum table and a stainless steel connecting pipe, the middle stainless steel table comprises a middle table body and a middle table connecting pipe, and the upper molybdenum table and the middle table body are welded and fixed through an upper welding piece and define an upper cooling cavity; the lower molybdenum table and the upper molybdenum table and / or the middle table body are welded and fixed through a middle soldering lug, a lower cooling cavity is defined by the lower molybdenum table and the middle table body, and the stainless steel connecting pipe is welded and fixed to the bottom of the lower molybdenum table through a lower soldering lug. Diamonds can directly grow on the composite growth base table, heat generated by diamond growth can be directly taken away, heat transfer is reduced, and the cooling and heat dissipation effects are better. The welding effect between dissimilar materials is guaranteed in a brazing mode, the welded connecting pipe can be prolonged in the welding mode, the corrosion resistance of the connecting pipe is guaranteed, and meanwhile the situation that the materials cannot be melted when brazing is conducted in a heating furnace is considered.

Description

Technical Field

[0001] The invention relates to a composite growth base for diamond synthesis, belonging to the technical field of preparing diamonds by chemical vapor deposition method. Background Art

[0002] Microwave plasma chemical vapor deposition (MPCVD) is the preferred method for producing high-quality single-crystal diamond. Single-crystal diamond growth occurs on a growth stage assembly consisting of a water-cooled stage and a growth base. Traditionally, the growth base is a solid molybdenum stage. This growth base is tuned by adjusting its configuration (single-piece, double-layer, triple-layer, or multi-layer, using a high-thermal-conductivity copper base) and structure (solid, with a central annular groove) to adjust its overall temperature and heat dissipation, thereby ensuring consistent and uniform temperature distribution throughout the single-crystal diamond sheet. This approach presents limitations in temperature regulation. Each temperature test requires the machine to be shut down and the growth base configuration adjusted until the desired temperature is achieved. Furthermore, under high power and high pressure conditions (where the growth temperature of single-crystal diamond is already far above the required process temperature), relying solely on heat transfer from the growth base to the water-cooled stage is insufficient for temperature regulation.

[0003] In this regard, the Chinese invention patent application with application publication number CN116695099A discloses a liftable MPCVD growth table, which includes a lower sealing plate, a lifting drive device, a first water-cooling assembly, and a second water-cooling assembly. A diamond growth table is provided on the top of the lower sealing plate, and a lifting groove and a positioning ring for placing a molybdenum support (i.e., a molybdenum table) are provided on the diamond growth table. The lifting drive device is connected to the positioning ring in a transmission manner to control its lifting and lowering in the lifting groove. The first water-cooling assembly is used to cool the positioning ring, including a first lifting water pipe and a second lifting water pipe nested from the outside to the inside. The bottoms of the two lifting water pipes are connected to the first water nozzle sleeve, and the tops are respectively connected to the first cooling water inlet plate and the first cooling water outlet plate. A sealing water plate is provided under the positioning ring. The first cooling water inlet plate divides the inner cavity of the sealing water plate into an upper first cooling water inlet cavity and a lower first cooling water outlet cavity. The coolant enters the upper first cooling water inlet cavity through the second lifting water pipe, and then enters the lower first cooling water outlet cavity through the connecting water hole on the first cooling water inlet plate, and then is discharged through the annulus between the first lifting water pipe and the second lifting water pipe to achieve cooling of the positioning ring.

[0004] The positioning ring, sealing water plate, first cooling water inlet plate, and first cooling water outlet plate above form a growth platform with a built-in cooling water chamber for the molybdenum holder (i.e., molybdenum table). Heat generated during diamond growth is transferred from the molybdenum table to the growth platform, where it is then dissipated by the water cooling system. However, because the heat is transferred through the first stage, the water cooling system cannot directly dissipate heat from the molybdenum table, significantly reducing the effectiveness of regulating the diamond growth temperature and affecting the quality and efficiency of diamond synthesis.

[0005] If the growth base is directly made into a molybdenum table for diamond growth, since an upper cooling cavity and a lower cooling cavity need to be set up in the growth base, it still has a three-layer structure, namely an upper table, a middle table and a lower table. The upper table and the middle table form an upper cooling cavity, and the middle table and the lower table form a lower cooling cavity. The upper and lower tables are generally fixed with screws, and the middle table is clamped between the two. In order to ensure the sealing, a sealing ring needs to be set between the joint surfaces of the upper and lower tables. However, if the growth base is directly used for diamond growth, the table temperature is high, and the sealing ring is more easily aged by temperature, affecting the sealing effect. In addition, the water circulation in the cooling cavity has a certain pressure, so it is more prone to leakage. Therefore, this structural form is unreliable and the welding method needs to be considered.

[0006] However, molybdenum has an extremely high melting point, making fusion welding poorly weldable and prone to welding defects. Therefore, brazing with welding sheets was the only option. Furthermore, the water-cooling system's pipes needed to be corrosion-resistant and extendable by welding. Furthermore, the pipes needed to prevent melting during brazing in the heating furnace (i.e., their melting point couldn't be too low). Furthermore, the center stage primarily separated the upper and lower cooling chambers, raising urgent questions about simplifying its structure and ensuring weldability between the center stage and the corresponding pipes. Summary of the Invention

[0007] The object of the present invention is to provide a composite growth base for diamond synthesis, so as to solve the problem in the prior art that a molybdenum table is placed on a growth base with a cooling water chamber for diamond growth. The heat generated during the diamond growth process is transferred to the growth base through the molybdenum table, and then dissipated from the growth base through a water cooling system. The heat is transferred through the first stage, and the water cooling system cannot directly dissipate the heat from the molybdenum table, resulting in a significant reduction in the effect of adjusting the diamond growth temperature, thereby affecting the quality and efficiency of diamond synthesis.

[0008] To achieve the above objectives, the composite growth base for diamond synthesis in the present invention adopts the following technical solutions: A composite growth base for diamond synthesis comprises a molybdenum upper platform, a stainless steel middle platform, a molybdenum lower platform and a stainless steel pipe. The stainless steel middle platform comprises a middle platform body and a middle platform pipe welded and fixed to the middle platform body and extending downward. The molybdenum upper platform and the middle platform body are welded and fixed by an upper welding piece, and an upper cooling cavity is formed between the two. The middle platform pipe is connected to the upper cooling cavity. The molybdenum lower platform is welded and fixed to the molybdenum upper platform and / or the middle platform body by a middle welding piece, and a lower cooling cavity is formed between the molybdenum lower platform and the middle platform body. A connecting hole connecting the upper and lower cooling cavities is provided on the middle platform body. The stainless steel pipe is welded and fixed to the bottom of the molybdenum lower platform by a lower welding piece. The middle platform pipe passes through the molybdenum lower platform and the stainless steel pipe, and the annulus between the middle platform pipe and the stainless steel pipe is connected to the lower cooling cavity.

[0009] The beneficial effects of the above technical solution are: the present invention is a pioneering invention, which proposes a composite growth base, including a molybdenum upper platform, a stainless steel middle platform, a molybdenum lower platform and a stainless steel pipe, wherein the stainless steel middle platform includes a middle platform body and a middle platform pipe that is welded and fixed to the middle platform body and extends downward, that is, the middle platform body and the middle platform pipe are both made of stainless steel, belonging to the same material, and the weldability of stainless steel is relatively good, and they can be welded and fixed by fusion welding, so the middle platform body and the middle platform pipe can be welded and fixed in advance, and then assembled with other components and put into the heating furnace for brazing, and the melting point of stainless steel is relatively high, and it will not melt during the brazing process, taking into account the feasibility of brazing. In addition, after the brazing is completed, the middle platform pipe can also be easily connected to the stainless steel pipe by fusion welding, which not only realizes the extension of the pipe, but also ensures the corrosion resistance of the pipe.

[0010] The molybdenum upper platform and the middle platform body are made of different materials, so the two are fixed by welding with the upper welding piece, that is, the connection between the two is achieved by brazing, and an upper cooling cavity is formed between the two. The middle platform pipe is connected to the upper cooling cavity for the coolant to enter or exit.

[0011] The molybdenum lower platform and the middle platform body are also made of different materials. Although the molybdenum lower platform and the molybdenum upper platform are made of the same material, it is difficult to fix them by fusion welding. Therefore, the molybdenum lower platform and the molybdenum upper platform and / or the middle platform body are welded and fixed by the middle welding piece, that is, the connection between the molybdenum lower platform and the molybdenum upper platform and / or the middle platform body is achieved by brazing, thereby realizing the composite growth base forming a whole.

[0012] A lower cooling cavity is formed between the molybdenum lower platform and the middle platform body, and the annulus between the middle platform pipe and the stainless steel pipe is connected to the lower cooling cavity. At the same time, a connecting hole connecting the upper and lower cooling cavities is provided on the middle platform body, so that the coolant enters the upper cooling cavity from the middle platform pipe, then enters the lower cooling cavity through the connecting hole, and finally flows out from the annulus between the middle platform pipe and the stainless steel pipe, or the coolant enters the lower cooling cavity from the annulus between the middle platform pipe and the stainless steel pipe, then enters the upper cooling cavity through the connecting hole, and finally flows out from the middle platform pipe, thereby realizing the circulation of the coolant and cooling and heat dissipation of the composite growth base.

[0013] In addition, the molybdenum upper platform can be directly used for diamond growth, and there is no need to place another molybdenum platform. The coolant directly cools and dissipates heat on the composite growth base. The heat generated by diamond growth is directly taken away, reducing heat transfer and achieving better cooling and heat dissipation effects, which is beneficial to improving the quality and efficiency of diamond synthesis.

[0014] Because the molybdenum lower plate and stainless steel pipe are made of dissimilar materials, they are fixed together using a lower welding piece, or brazing. The stainless steel pipe must be brazed in the heating furnace along with the molybdenum upper plate, stainless steel middle plate, and molybdenum lower plate. Otherwise, the stainless steel pipe cannot be subsequently welded to the molybdenum lower plate. Furthermore, after brazing, the stainless steel pipe can be easily connected to the stainless steel pipe by fusion welding, which not only extends the pipe but also ensures its corrosion resistance.

[0015] Furthermore, a convex ring extending downward is integrally connected to the bottom of the molybdenum lower platform, and an outward-extending rim is provided at the upper end of the stainless steel pipe. During welding, the lower welding piece is clamped between the outward-extending rim and the molybdenum lower platform. The stainless steel pipe is sleeved on the outside of the convex ring and utilizes the difference in thermal expansion between the two to create an annular gap between the two for the lower welding piece to be filled with the melted welding liquid.

[0016] Furthermore, a ring groove is provided on the bottom surface of the molybdenum lower platform around the convex ring, and the lower welding piece and the outward turning edge are both located in the ring groove during welding, so that the outward turning edge does not protrude from the bottom surface of the molybdenum lower platform after welding.

[0017] Furthermore, during welding, the molybdenum upper platform, stainless steel middle platform, molybdenum lower platform and stainless steel pipe are inverted in the heating furnace, and a counterweight block with a melting point greater than or equal to the melting point of stainless steel is used to apply downward pressure to the outward edge. The counterweight block is provided with a through hole for the middle platform pipe and the stainless steel pipe to pass through.

[0018] Furthermore, a central groove and a plurality of upper flow channels connected to the central groove and arranged in a scattered manner are provided on the molybdenum upper platform. An upper central hole corresponding to the central groove and a plurality of upper through holes connected to the upper central hole and arranged in a scattered manner are provided on the upper welding plate. The upper through holes correspond to the upper flow channels one by one and have the same shape. The upper end surface of the middle platform body and the upper through holes and upper flow channels together form an upper cooling cavity.

[0019] Furthermore, the molybdenum lower platform is provided with a lower center hole connected to the stainless steel pipe and a plurality of lower flow channels connected to the lower center hole and arranged in a scattered manner. The middle welding plate is provided with a through hole corresponding to the lower center hole and for the middle platform pipe to pass through, and a plurality of lower through holes connected to the through holes and arranged in a scattered manner. The lower through holes correspond to the lower flow channels one by one and have the same shape. The lower end surface of the middle platform body and the lower through holes and the lower flow channels together form a lower cooling chamber.

[0020] Furthermore, corresponding upper and lower positioning holes for installing positioning pins are respectively provided on the boss between two adjacent upper flow channels, on the sheet between two adjacent upper through holes, on the middle platform body, on the sheet between two adjacent lower through holes, and on the boss between two adjacent lower flow channels.

[0021] Furthermore, each of the upper through hole, the upper flow channel, the lower through hole and the lower flow channel is fan-shaped.

[0022] Furthermore, a stepped groove with a notch facing downward is provided on the molybdenum upper platform, and the stepped groove includes a small-diameter groove at the top and a large-diameter groove at the bottom. The upper flow channel is arranged on the bottom wall of the small-diameter groove. The upper welding piece and the middle platform body are both located in the small-diameter groove and their outer diameters are equal to the inner diameter of the small-diameter groove. The middle welding piece and the molybdenum lower platform are both located in the large-diameter groove and their outer diameters are equal to the inner diameter of the large-diameter groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A structural diagram of the composite growth base for diamond synthesis of the present invention and its connected pipes, water blocks and lifting drive device; Figure 2 for Figure 1 Enlarged image of the upper middle part; Figure 3 An exploded view of the composite growth base for diamond synthesis of the present invention before welding; Figure 4 This is an exploded view of the composite growth base for diamond synthesis of the present invention before welding from another perspective; Figure 5 This is a state diagram of the composite growth base for diamond synthesis during the welding process of the present invention; Figure 6 An exploded view of the composite growth base, counterweight, and spacer for diamond synthesis according to the present invention; Figure 7 for Figure 1 A magnified view of the water aggregate; Figure 8 A three-dimensional diagram of a water block, a hoop and a collar connected to a composite growth base for diamond synthesis according to the present invention; Figure 9 This is a diagram showing the usage status of the composite growth base for diamond synthesis according to the present invention.

[0024] In the figure: 100, cavity; 200, cavity bottom plate; 300, water-cooling platform; 400, composite growth base; 1, molybdenum upper platform; 1-1, center groove; 1-2, upper flow channel; 1-3, first positioning hole; 1-4, small diameter groove; 1-5, large diameter groove; 2, middle platform body; 2-1, connecting hole; 2-2, second positioning hole; 3, middle platform pipe; 4, molybdenum lower platform; 4-1, convex ring; 4-2, ring groove; 4-3, lower center hole; 4-4, lower flow channel; 5, stainless steel pipe; 5-1, outer edge; 5-2, annular protrusion; 6, upper welding piece; 6-1, upper center hole; 6-2, upper through hole; 6-3, third positioning hole; 7, middle welding piece; 7-1, through hole; 7-2, lower through hole; 7-3, Fourth positioning hole; 8. Lower welding piece; 9. Positioning pin; 10. External pipe; 11. Internal pipe; 12. Water collection block; 12-1. Upper block; 12-2. Lower block; 12-3. Plug; 12-4. Nut cover; 12-5. Sealing ring; 12-6. First sealing ring; 12-7. Second sealing ring; 12-8. Third sealing ring; 12-9. Lower joint; 12-10. Upper joint; 12-11. Bottom threaded hole; 12-12. Side threaded hole; 13. Hoop; 13-1. First holding ring; 13-2. Second holding ring; 13-3. Locking bolt; 14. Ring; 15. Fixing bolt; 16. Counterweight; 16-1. Through hole; 17. Isolation plate; 18. Lifting motor. DETAILED DESCRIPTION

[0025] To address the technical issues existing in the prior art, the present invention provides a growth platform made of a molybdenum and stainless steel composite material, on which diamonds can be grown directly. This platform also features a water-cooling structure that directly removes heat generated by diamond growth, reducing heat transfer and improving cooling and heat dissipation. Furthermore, brazing is employed to ensure effective welding between dissimilar materials, enabling the pipe to be extended after welding and ensuring corrosion resistance. Furthermore, the material does not melt during brazing in a heating furnace.

[0026] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0027] Implementation methods of the composite growth platform for diamond synthesis (abbreviated as composite growth platform) in the present invention: like Figure 1 and Figure 2As shown, the composite growth base 400 includes a molybdenum upper base 1, a stainless steel middle base, a molybdenum lower base 4, and a stainless steel pipe 5. The stainless steel middle base includes a middle base body 2 and a middle base pipe 3 welded to the middle base body 2 and extending downward. Both the middle base body 2 and the middle base pipe 3 are made of stainless steel, which is the same material. Stainless steel has good weldability and can be welded together using mature fusion welding processes (such as laser welding or argon arc welding), ensuring the strength and sealing of the welded connection. Therefore, when manufacturing the composite growth base, the middle base body 2 and the middle base pipe 3 can be welded together in advance and then assembled with other components in a heating furnace for brazing. Due to the high melting point of stainless steel, it does not melt during the brazing process, which takes into account the feasibility of brazing. In addition, the middle base pipe 3 is of appropriate length to allow it to be placed in the heating furnace. After brazing, it can be further connected to the stainless steel pipe by fusion welding, which not only extends the pipe but also ensures its corrosion resistance.

[0028] Combine Figure 3 、 Figure 4 and Figure 5 As shown, the molybdenum upper platform 1 and the middle platform body 2 are welded and fixed by the upper welding plate 6, and an upper cooling cavity is formed between the two, and the middle platform pipe 3 is connected to the upper cooling cavity. The molybdenum lower platform 4 is welded and fixed to the molybdenum upper platform 1 and the middle platform body 2 by the middle welding plate 7, and a lower cooling cavity is formed between the molybdenum lower platform 4 and the middle platform body 2. The middle platform body 2 is provided with a connecting hole 2-1 connecting the upper and lower cooling cavities, and a plurality of connecting holes 2-1 are evenly distributed on the same circumference to ensure that the coolant in the upper and lower cooling cavities can flow smoothly. The stainless steel pipe 5 is welded and fixed to the bottom of the molybdenum lower platform 4 by the lower welding plate 8. The middle platform pipe 3 passes through the molybdenum lower platform 4 and the stainless steel pipe 5, and the annular space between the middle platform pipe 4 and the stainless steel pipe 5 is connected to the lower cooling cavity.

[0029] In this way, the coolant can enter the upper cooling chamber through the middle platform pipe 3, then enter the lower cooling chamber through the connecting hole 2-1, and finally flow out from the annulus between the middle platform pipe 3 and the stainless steel pipe 5. Alternatively, the coolant can enter the lower cooling chamber through the annulus between the middle platform pipe 3 and the stainless steel pipe 5, then enter the upper cooling chamber through the connecting hole 2-1, and finally flow out from the middle platform pipe 3, thus achieving a circulating flow of the coolant and thus achieving cooling and heat dissipation of the composite growth base. In addition, the molybdenum upper platform 1 can directly serve as a source of diamond growth, eliminating the need for a separate molybdenum platform. The coolant directly cools and dissipates heat from the composite growth base, directly carrying away the heat generated by diamond growth, reducing heat transfer and achieving better cooling and heat dissipation effects, which is conducive to improving the quality and efficiency of diamond synthesis.

[0030] The molybdenum upper platform 1 and the middle platform body 2 are made of different materials. Considering the problems of oxidation and brittleness of molybdenum welding, the two are fixed by welding with the upper welding plate 6, that is, the connection between the two is achieved by brazing. The reason why the middle platform body 2 is made of stainless steel is, on the one hand, considering that it needs to be welded with a pipe. To ensure corrosion resistance, brazing feasibility and pipe extension, the pipe needs to be a stainless steel pipe, so the middle platform body 2 uses a stainless steel plate of the same material; on the other hand, considering that the main function of the middle platform body 2 is to separate the upper and lower cooling chambers, the simpler the structure, the better, so a thinner stainless steel plate is selected to make the middle platform body 2.

[0031] Specifically in this embodiment, the molybdenum upper platform 1 is provided with a central groove 1-1 and a plurality of upper flow channels 1-2 (six in this embodiment) connected to the central groove 1-1 and arranged in a scattered manner. The upper welding plate 6 is provided with an upper center hole 6-1 corresponding to the central groove 1-1 and a plurality of upper through holes 6-2 (also six) connected to the upper center hole 6-1 and arranged in a scattered manner. The upper through holes 6-2 correspond to the upper flow channels 1-2 one by one and have the same shape. The upper end surface of the middle platform body 2 and each upper through hole 6-2 and the upper flow channel 1-2 together form an upper cooling cavity.

[0032] In this way, if the coolant enters the upper cooling cavity from the middle platform pipe 3, it will diverge to the multiple upper flow channels 1-2 through the central groove 1-1. Through the guidance of the multiple upper flow channels 1-2, the coolant has a certain flow path, which can ensure the cooling and heat dissipation effect of the molybdenum upper platform 1. At the same time, each connecting hole 2-1 on the middle platform body 2 corresponds to each upper flow channel 1-2, that is, there are six connecting holes 2-1, and the connecting holes 2-1 are located at a position corresponding to the edge of the upper flow channel 1-2. In this way, after the coolant reaches the edge of the upper flow channel 1-2, it enters the lower cooling cavity through the connecting holes 2-1, ensuring the cooling and heat dissipation effect of the molybdenum upper platform 1. Of course, if the coolant enters the lower cooling cavity first, it will enter the corresponding upper flow channel 1-2 through each connecting hole 2-1, and finally converge into the central groove 1-1, and then be discharged through the middle platform pipe 3. Of course, considering that the molybdenum upper platform 1 is directly used for diamond growth and the temperature is higher, it is preferred that the coolant enters the upper cooling cavity first and then enters the lower cooling cavity.

[0033] Since each upper through hole 6-2 needs to be connected to the upper flow channel 1-2 in a one-to-one correspondence, it is necessary to ensure that the upper welding piece 6 is correctly positioned during assembly before welding. Therefore, corresponding positioning holes for mounting positioning pins 9 are provided on the boss between two adjacent upper flow channels 1-2, on the sheet between two adjacent upper through holes 6-2, and on the middle platform body 2. In this embodiment, there are two positioning pins 9, so two first positioning holes 1-3 (both blind holes) are provided on the molybdenum upper platform 1, and the two first positioning holes 1-3 are located on two symmetrically arranged bosses; two second positioning holes 2-2 (both through holes) are provided on the middle platform body 2, and the two second positioning holes 2-2 are arranged 180 degrees symmetrically; and two third positioning holes 6-3 (both through holes) are provided on the upper welding piece 6, and the two third positioning holes 6-3 are located on the two symmetrically arranged sheets.

[0034] The upper welding sheet 6 is a circular sheet. Except for the upper center hole 6-1, the upper through hole 6-2, and the third positioning hole 6-3, the solid sheet parts are all in contact with the molybdenum upper platform 1, and these solid sheet parts are located between the circular middle platform body 2 and the molybdenum upper platform 1, ensuring that there is sufficient contact area between the upper welding sheet 6 and the molybdenum upper platform 1 and the middle platform body 2. This contact area is also the welding area, thereby ensuring the welding connection effect between the molybdenum upper platform 1 and the middle platform body 2.

[0035] Furthermore, each of the upper through holes 6-2 and the upper flow channel 1-2 in the present embodiment is fan-shaped, which not only ensures that the welding area is sufficient, but also takes into account the cooling and heat dissipation effect. In other embodiments, the number of the upper through holes 6-2 and the upper flow channel 1-2 can be adjusted according to actual needs. In other embodiments, each of the upper through holes 6-2 and the upper flow channel 1-2 can also be rectangular or spiral. Of course, in other embodiments, the upper flow channel 1-2 can also be not provided on the molybdenum upper platform 1, but an upper cooling cavity is formed by a groove. In this case, the upper cooling cavity is a through cavity, and there are no multiple flow channels. In this case, the upper through hole 6-2 is no longer provided on the upper welding plate 6. The upper welding plate 6 is an annular plate, and the inner hole diameter of the annular plate is the same as the inner diameter of the groove of the molybdenum upper platform 1. The entity part of the annular plate is in physical contact with the outer periphery of the groove to achieve a certain welding area between the middle platform body 2 and the molybdenum upper platform 1.

[0036] In this embodiment, the molybdenum upper platform 1 has the largest size, and is provided with a stepped groove with the notch facing downward. The stepped groove includes a small-diameter groove 1-4 on the top and a large-diameter groove 1-5 on the bottom. The above-mentioned upper flow channel 1-2 is arranged on the bottom wall of the small-diameter groove 1-4. During assembly before welding, the upper welding piece 6 and the middle platform body 2 are both located in the small-diameter groove 1-4 and the outer diameters are equal to the inner diameter of the small-diameter groove 1-4, and the lower end face of the middle platform body 2 is flush with the bottom wall of the large-diameter groove 1-5, so that the middle welding piece 7 can contact the bottom wall of the large-diameter groove 1-5 and the lower end face of the middle platform body 2 at the same time, so that the molybdenum lower platform 4 can be welded and fixed to the molybdenum upper platform 1 and the middle platform body 2 through the middle welding piece 7, thereby ensuring the overall welding and fixing strength of the composite growth base 400.

[0037] The outer diameter of the middle welding piece 7 is larger than that of the upper welding piece 6, and the outer diameter of the middle welding piece 7 is equal to the outer diameter of the molybdenum lower platform 4. The middle welding piece 7 and the molybdenum lower platform 4 are both located in the large diameter grooves 1-5 and the outer diameters are equal to the inner diameters of the large diameter grooves 1-5. At the same time, the lower end surface of the molybdenum lower platform 4 is flush with the lower end surface of the molybdenum upper platform 1, so that the lower end surface of the composite growth base 400 is flat. When used as Figure 9 As shown, the MPCVD equipment includes a chamber 100 and a chamber bottom plate 200. A water cooling stage 300 is provided on the chamber bottom plate 200. The lower end surface of the composite growth base 400 can be fitted with the upper end surface of the water cooling stage 300, thereby obtaining a further cooling effect through the water cooling stage 300.

[0038] like Figure 3 and Figure 4 As shown, the molybdenum lower platform 4 is provided with a lower center hole 4-3 connected to the stainless steel pipe 5, and multiple lower flow channels 4-4 (six in a scattered pattern) connected to the lower center hole 4-3. The middle welding plate 7 is provided with a through hole 7-1 corresponding to the lower center hole 4-3 and for the middle platform pipe 3 to pass through, and multiple lower through holes 7-2 (six in a scattered pattern) connected to the through hole 7-1. The lower through holes 7-2 are connected to the lower flow channels 4-4 in a one-to-one correspondence and have the same shape. The lower end surface of the middle platform body 2, the lower through holes 7-2, and the lower flow channels 4-4 together form a lower cooling chamber.

[0039] At the same time, each lower through hole 7-2 corresponds one-to-one to the connecting hole 2-1 on the middle platform body 2, so that the coolant enters each lower flow channel 4-4 from the upper cooling cavity and the connecting hole 2-1, and then converges to the lower center hole 4-3 and is discharged through the annular space between the stainless steel pipe 5 and the middle platform pipe 3, so that the coolant has a certain flow path in the lower cooling cavity, ensuring the cooling effect on the molybdenum lower platform 4.

[0040] Therefore, during assembly before welding, the position of the middle welding piece 7 must be placed correctly. Therefore, upper and lower positioning holes corresponding to the installation of the positioning pin 9 are provided on the piece body between the two adjacent lower through holes 7-2 and on the boss between the two adjacent lower flow channels 4-4, corresponding to the positioning holes on the molybdenum upper platform 1, the upper welding piece 6, and the middle platform body 2. Two fourth positioning holes 7-3 (both through holes) are provided on the middle welding piece 7, and two fifth positioning holes (both blind holes) are provided on the molybdenum lower platform 4. During assembly, place the molybdenum upper platform 1 on the workbench with the notch of its stepped groove facing upward, then install the positioning pins 9 in the two first positioning holes 1-3 respectively, and then put in the upper welding piece 6, the middle platform body 2 (the middle platform body 2 and the middle platform pipe 3 have been fixed in advance by fusion welding), and the middle welding piece 7 (the middle platform pipe 3 passes through the through-hole 7-1 when placed) in turn, so that the positioning pin 9 passes through the positioning holes opened on these components, and finally place the molybdenum lower platform 4 (the middle platform pipe 3 passes through the center hole 4-3 when placed), so that the positioning holes on the molybdenum lower platform 4 are aligned with the positioning pins 9, so as to achieve accurate positioning of each component and ensure that the flow channel design features can be assembled and aligned according to the design.

[0041] Of course, in other embodiments, a stepped groove with an upward opening can also be provided on the molybdenum lower platform 4. At this time, the size of the molybdenum lower platform 4 is the largest, and the middle platform body 2 and the molybdenum upper platform 1 are both embedded in the stepped groove of the molybdenum lower platform 4. When assembling before welding, the molybdenum lower platform 4 should be placed on the workbench first with the notch of its stepped groove facing upward, and then the positioning pins are installed in the two fifth positioning holes respectively, and then the middle welding piece 7, the middle platform body 2, the upper welding piece 6 and the molybdenum upper platform 1 are placed in turn. During the placement process, the positioning pins and the positioning holes are used to accurately position each component.

[0042] The middle welding piece 7 is also circular, with its outer portion contacting the bottom wall of the large-diameter groove 1-5, ensuring a sufficient welding area between the molybdenum lower platform 4 and the molybdenum upper platform 1. Except for the outer portion, the through-hole 7-1, the lower through-hole 7-2, and the fourth positioning hole 7-3, the remaining portion contacts the middle platform body 2 and the molybdenum lower platform 4, ensuring a sufficient welding area between the molybdenum lower platform 4 and the middle platform body 2.

[0043] Furthermore, each lower through hole 7-2 and lower flow channel 4-4 in this embodiment are fan-shaped, which not only ensures that the welding area is sufficient, but also takes into account the cooling and heat dissipation effect. In other embodiments, each lower through hole 7-2 and lower flow channel 4-4 can also be rectangular or spiral. Of course, in other embodiments, the molybdenum lower platform 4 can also be provided with no lower flow channel 4-4, but instead a lower cooling cavity is formed by a groove. In this case, the lower cooling cavity is a through cavity, and there are no multiple flow channels. In this case, the middle welding piece 7 is an annular piece, and the inner hole diameter of the annular piece is the same as the inner diameter of the groove of the molybdenum lower platform 4. The solid part of the annular piece is in physical contact with the outer periphery of the groove to achieve a certain welding area between the molybdenum lower platform 4 and the molybdenum upper platform 1. Of course, depending on the specific dimensions of the middle welding piece 7 and the groove, it is possible to achieve that the middle welding piece 7 is in contact with the middle platform body 2 and the molybdenum upper platform 1 at the same time, thereby achieving welding of the three components.

[0044] like Figure 3 、 Figure 5 and Figure 6 As shown, the molybdenum lower platform 4 and the stainless steel pipe 5 are made of dissimilar materials, so they are fixed by welding with the lower welding piece 8, that is, the connection between the two is achieved by brazing. The stainless steel pipe 5 must be brazed in the heating furnace along with the molybdenum upper platform 1, the stainless steel middle platform, and the molybdenum lower platform 4. Otherwise, the stainless steel pipe 5 cannot be welded to the molybdenum lower platform 4 later. In addition, the stainless steel pipe 5 has an appropriate length to be placed in the heating furnace. After the brazing is completed, the stainless steel pipe 5 can be easily connected to the stainless steel pipe by fusion welding, which not only extends the pipe but also ensures the corrosion resistance of the pipe.

[0045] Of course, the stainless steel pipe 5 is shorter than the middle pipe 3, so that the middle pipe 3 can pass through the stainless steel pipe 5. In this way, after the brazing is completed, both pipes can be extended by fusion welding.

[0046] To facilitate welding of the stainless steel pipe 5 and the molybdenum lower platform 4, a downward extending convex ring 4-1 is integrally connected to the bottom of the molybdenum lower platform 4, and an outward extending folded edge 5-1 is provided on the upper end of the stainless steel pipe 5. During welding, the lower welding piece 8 is clamped between the folded edge 5-1 and the molybdenum lower platform 4, and the stainless steel pipe 5 is sleeved on the outside of the convex ring 4-1, forming a relatively compact fit between the two (formulated according to the welding process). The thermal expansion coefficient of stainless steel is greater than that of molybdenum. During the heating process, the thermal expansion of the stainless steel pipe 5 is greater than that of the convex ring 4-1. The difference in thermal expansion causes the two to change from a tight fit to an annular gap. The welding liquid after the lower welding piece 8 is melted can infiltrate and fill the annular gap. After the welding is completed and cooled, the stainless steel pipe 5 contracts to achieve the effect of holding the convex ring 4-1 tightly, solving the problem of poor reliability in welding dissimilar metals and solving the most important welding problem.

[0047] Furthermore, an annular groove 4-2 is provided on the bottom surface of the molybdenum lower platform 4, surrounding the raised ring 4-1. During welding, the lower welding piece 8 and the outward-turned edge 5-1 are both located within the annular groove 4-2. This ensures that the outward-turned edge 5-1 does not protrude from the bottom surface of the molybdenum lower platform 4 after welding, and is flush with the bottom surface of the molybdenum lower platform 4, thereby ensuring that the lower end surface of the composite growth base 400 is flat. Of course, in other embodiments, if there is no water-cooling platform, or the water-cooling platform is an ordinary platform without cooling function, the lower end surface of the composite growth base may not be flat, that is, the annular groove 4-2 may not be provided on the bottom surface of the molybdenum lower platform 4. In this case, the lower welding piece 8 is directly sandwiched between the bottom surface of the molybdenum lower platform 4 and the outward-turned edge 5-1. After welding, the outward-turned edge 5-1 protrudes from the bottom surface of the molybdenum lower platform 4.

[0048] Before welding, the composite growth base needs to be assembled. Except for the middle platform body 2 and the middle platform pipe 3 which are fixed in advance by fusion welding, the remaining components need to be assembled in sequence, and the molybdenum upper platform 1, stainless steel middle platform, molybdenum lower platform 4 and stainless steel pipe 5 are inverted in the heating furnace. The heating furnace can be a vacuum heat treatment furnace, an ordinary air heating furnace or a protective atmosphere heating furnace.

[0049] like Figure 5 and Figure 6 As shown, downward pressure is applied to the outward-turned edge 5-1 by a counterweight 16 having a melting point greater than or equal to that of stainless steel. In this embodiment, the counterweight 16 is made of stainless steel; in other embodiments, it may be made of ceramic or graphite. Counterweight 16 is provided with a through hole 16-1 through which the center tube 3 and the stainless steel tube 5 pass. The main portion of the counterweight 16 has a large outer diameter, while the pressure-bearing portion has a smaller outer diameter, which helps concentrate pressure on the outward-turned edge 5-1. The stepped surface formed between the two portions facilitates the movement of the counterweight 16.

[0050] The function of the counterweight 16 is to ensure that capillary gaps are formed between the molybdenum upper platform 1 and the middle platform body 2, between the molybdenum upper platform 1 and the molybdenum lower platform 4, between the middle platform body 2 and the molybdenum lower platform 4, and between the molybdenum lower platform 4 and the outer edge 5-1. This promotes the molten solder to flow and infiltrate better through capillary action, filling the fitting gaps. In addition, the middle platform body 2 is nickel-plated to increase the wettability of the solder after melting, improve the welding quality between the molybdenum upper platform 1, the middle platform body 2, and the molybdenum lower platform 4, and achieve the purpose of fixing the stainless steel middle platform.

[0051] At the same time, an annular protrusion 5-2 is formed on the outer peripheral surface of the stainless steel pipe 5, and its longitudinal section is arc-shaped. The annular protrusion 5-2 contacts and cooperates with the hole wall of the through hole 16-1 to ensure the positioning accuracy of the counterweight block 16.

[0052] Furthermore, if the counterweight 16 is made of stainless steel, a spacer 17 is placed between the counterweight 16 and the molybdenum lower platform 4. Spacer 17 is positioned between the counterweight 16 and the outer edge 5-1 to prevent the molten solder from overflowing and welding the counterweight 16 and the composite growth base together. Spacer 17 can be a mica sheet, a ceramic sheet, or a graphite sheet. Of course, if the counterweight 16 is made of ceramic or graphite, a spacer is not required.

[0053] like Figure 1 、 Figure 2 、 Figure 7 and Figure 8 As shown, after the composite growth base is welded and secured, it is necessary to weld and secure an internal pipe 11 to the central pipe 3 and an external pipe 10 to the stainless steel pipe 5 to extend the pipe. A water block 12 is connected to the lower portions of the internal and external pipes 11 and 10. This water block 12 comprises a water block body and a plug 12-3 sealed and fixedly connected to the upper end of the water block body. The water block body comprises an upper block 12-1 and a lower block 12-2. The plug 12-3 is threadedly connected to the upper end opening of the upper block 12-1. A first sealing ring 12-6 is provided at the interface between the plug 12-3 and the upper block 12-1 to achieve a seal between the two.

[0054] The lower end of the external pipe 10 passes through the plug 12-3 and extends into the upper block 12-1. The upper block 12-1 is provided with a top step, and the lower end of the external pipe 10 contacts the top step. A nut cover 12-4 is threadedly connected to the top of the plug 12-3. The external pipe 10 passes through the nut cover 12-4. A sealing ring 12-5 is provided between the upper end opening of the plug 12-3 and the outer peripheral surface of the external pipe 10. When the nut cover 12-4 is tightened, the nut cover 12-4 squeezes the sealing ring 12-5, achieving a seal between the plug 12-3 and the external pipe 10, preventing the liquid in the water block 12 from leaking out. At the same time, under the friction of the sealing ring 12-5, a certain bonding force is achieved between the water block 12 and the external pipe 10.

[0055] The lower end of the internal pipe 11 passes through the external pipe 10 and through the upper block 12-1 into the lower block 12-2. A second sealing ring 12-7 is provided between the interface between the upper block 12-1 and the lower block 12-2 and the outer circumference of the internal pipe 11. Both the upper block 12-1 and the lower block 12-2 have flanges, which are fixedly connected by bolts. During fastening, the end faces of the two blocks squeeze the second sealing ring 12-7, achieving a seal between the two blocks and between the internal pipe 11 and the two blocks, preventing coolant in the lower block 12-2 from entering the annulus between the internal pipe 11 and the external pipe 10 through the gap between the internal pipe 11 and the two blocks.

[0056] A third sealing ring 12-8 is further provided between the end faces of the upper block 12-1 and the lower block 12-2. The third sealing ring 12-8 is coaxially arranged on the outside of the second sealing ring 12-7, thereby enhancing the sealing effect between the two blocks.

[0057] An upper joint 12-10 is sealed on the upper block 12-1 and is connected to the annulus between the inner pipe 11 and the outer pipe 10. A lower joint 12-9 is sealed on the lower block 12-2 and is connected to the inner pipe 11. The lower joint 12-9 and the upper joint 12-10 are arranged on the same side of the water block 12 to facilitate connection with the external cooling system.

[0058] In this embodiment, the lower joint 12-9 serves as the water inlet joint, and the upper joint 12-10 serves as the water outlet joint. This allows the coolant to enter the internal pipe 11 through the lower joint 12-9, then flow upward through the middle pipe 3 into the upper cooling chamber within the composite growth base 400. The coolant then flows from the center to the periphery and flows into the lower cooling chamber along the connecting hole 2-1 on the middle body 2. The coolant then converges at the center and flows downward along the annulus between the stainless steel pipe 5 and the external pipe 10, and the middle pipe 3 and the internal pipe 11, to the water block 12. Finally, it flows through the upper joint 12-10 to the external cooling system, thereby cooling the composite growth base 400. In other embodiments, the lower joint 12-9 may also serve as the water outlet joint, in which case the upper joint 12-10 serves as the water inlet joint.

[0059] A lifting drive is connected below the water block 12. This drive is used to move the water block 12, the internal pipe 11, the external pipe 10, and the composite growth base 400 up and down, thereby adjusting the height of the composite growth base 400 and enhancing the cooling effect of the water cooling stage 300 on the composite growth base 400. In this embodiment, the lifting drive is a lifting motor 14; other embodiments may also employ a hydraulic cylinder or pneumatic cylinder.

[0060] Specifically, a bottom threaded hole 12-11 is provided on the bottom surface of lower block 12-2. The lifting drive device includes a screw connected to bottom threaded hole 12-11, i.e., the top output end of lifting motor 14 is a screw. Furthermore, a side threaded hole 12-12 is provided on the side of lower block 12-2, vertically connected to bottom threaded hole 12-11. A jackscrew installed in side threaded hole 12-12 can tighten the screw, preventing the connection between lifting motor 14 and water block 12 from loosening, and also serves to adjust the position of the screw in bottom threaded hole 12-11.

[0061] In addition, combined Figure 1 and Figure 8As shown, the nut cover 12-4 is fixedly connected with a clamp 13 for clamping and fixing on the external pipe 10 after the nut cover 12-4 is installed. In this way, after the nut cover 12-4 is tightened to achieve the seal between the sealing ring 12-5 and the external pipe 10, the water block 12 is indirectly fixed to the external pipe 10 through the rigid connection between the clamp 16 and the external pipe 10, so that when the lifting motor 14 drives the water block 12 to move up and down, the water block 12 can stably drive the external pipe 10 to move up and down, preventing the connection position from slipping during the lifting process or due to water pressure fluctuations.

[0062] A collar 14 is provided below the nut cover 12-4 and is sleeved around the outside of the plug 12-3. A hoop 13 is positioned above the nut cover 12-4. The hoop 13 and collar 14 are fixedly connected by at least two fixing bolts 15, thereby clamping the nut cover 12-4 between the hoop 13 and collar 14. The hoop 13 includes two separate collars, a first collar 13-1 and a second collar 13-2, which are fixedly connected by two locking bolts 13-3. Each collar has an arcuate groove for clamping the outer circumference of the external tube 10.

[0063] During assembly, after the nut cover 12-4 is installed, first tighten the fixing bolt 15 to ensure that the two holding rings and the collar 14 have an initial clamping force on the middle nut cover 12-4, but do not clamp them tightly. Otherwise, the two holding rings will be fixed in position and will no longer be able to clamp the external tube 10. Then install the locking bolt 13-3. The gap between the fixing bolt 15 and the bolt holes in the holding rings allows the two holding rings to move relative to each other to clamp the outer circumference of the external tube 10. Of course, it is necessary to tighten the fixing bolt 15 during installation to ensure that the holding ring 13 holds the external tube 10 while the holding ring 13 and the collar 14 also clamp the nut cover 12-4. Of course, you can also tighten the locking bolt 13-3 first to ensure that the two holding rings have an initial clamping force on the external tube 10, but do not clamp them tightly, and then install the fixing bolt 15 and tighten the locking bolt 13-3 during installation.

[0064] In other embodiments of the composite growth base, when assembling the components of the composite growth base, positioning pins may no longer be used. In this case, positioning holes do not need to be provided in the components, and the placement of the components only needs to be controlled.

[0065] In other embodiments of the composite growth base, depending on the actual weight of each component, the counterweight block may no longer be used, and the capillary gap may be formed by the weight of the component.

[0066] In other embodiments of the composite growth base: the lower welding piece only realizes the welding between the outward-turned edge and the molybdenum lower platform, that is, the convex ring is no longer provided; or the lower welding piece is annular and is sleeved on the outside of the convex ring to realize the welding between the convex ring and the stainless steel pipe and between the outward-turned edge and the molybdenum lower platform.

[0067] In other embodiments of the composite growth base, the middle welding piece can only realize welding between the molybdenum lower platform and the middle platform body.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be based on the claims. Any equivalent structural changes made using the description and drawings of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A composite growth base for diamond synthesis, characterized in that: It includes a molybdenum upper platform, a stainless steel middle platform, a molybdenum lower platform and a stainless steel pipe. The stainless steel middle platform includes a middle platform body and a middle platform pipe welded to the middle platform body and extending downward. The molybdenum upper platform and the middle platform body are welded and fixed by an upper welding piece, and an upper cooling cavity is formed between the two. The middle platform pipe is connected to the upper cooling cavity. The molybdenum lower platform is welded and fixed to the molybdenum upper platform and / or the middle platform body by a middle welding piece, and a lower cooling cavity is formed between the molybdenum lower platform and the middle platform body. A connecting hole connecting the upper and lower cooling cavities is provided on the middle platform body. The stainless steel pipe is welded and fixed to the bottom of the molybdenum lower platform through the lower welding piece. The middle platform pipe passes through the molybdenum lower platform and the stainless steel pipe, and the annulus between the middle platform pipe and the stainless steel pipe is connected to the lower cooling cavity.

2. The composite growth base for diamond synthesis according to claim 1, wherein: The bottom of the molybdenum lower platform is integrally connected with a convex ring extending downward, and the upper end of the stainless steel pipe is provided with an outward-extending outward-facing edge. During welding, the lower welding piece is clamped between the outward-facing edge and the molybdenum lower platform. The stainless steel pipe is sleeved on the outside of the convex ring and utilizes the difference in thermal expansion between the two to create an annular gap between the two for the lower welding piece to be filled with the melted welding liquid.

3. The composite growth base for diamond synthesis according to claim 2, wherein: A ring groove is provided on the bottom surface of the molybdenum lower platform around the convex ring. During welding, the lower welding piece and the outward-turned edge are both located in the ring groove so that the outward-turned edge does not protrude from the bottom surface of the molybdenum lower platform after welding.

4. The composite growth base for diamond synthesis according to claim 2, wherein: During welding, the molybdenum upper platform, stainless steel middle platform, molybdenum lower platform and stainless steel pipe are inverted in the heating furnace, and a counterweight block with a melting point greater than or equal to the melting point of stainless steel is used to apply downward pressure on the outward edge. The counterweight block is provided with through holes for the middle platform pipe and the stainless steel pipe to pass through.

5. The composite growth base for diamond synthesis according to any one of claims 1 to 4, characterized in that: The molybdenum upper platform is provided with a central groove and a plurality of upper flow channels connected to the central groove and arranged in a scattered manner. The upper welding plate is provided with an upper central hole corresponding to the central groove and a plurality of upper through holes connected to the upper central hole and arranged in a scattered manner. The upper through holes correspond to the upper flow channels one by one and have the same shape. The upper end surface of the middle platform body and the upper through holes and upper flow channels together form an upper cooling cavity.

6. The composite growth base for diamond synthesis according to claim 5, characterized in that: The molybdenum lower platform is provided with a lower center hole connected to the stainless steel pipe and a plurality of lower flow channels connected to the lower center hole in a scattered manner. The middle welding plate is provided with a through hole corresponding to the lower center hole for the middle platform pipe to pass through, and a plurality of lower through holes connected to the through holes in a scattered manner. The lower through holes correspond to the lower flow channels one by one and have the same shape. The lower end surface of the middle platform body and the lower through holes and the lower flow channels together form a lower cooling cavity.

7. The composite growth base for diamond synthesis according to claim 6, characterized in that: Positioning holes corresponding to the upper and lower parts and used to install positioning pins are respectively provided on the boss between two adjacent upper flow channels, on the sheet between two adjacent upper through holes, on the middle platform body, on the sheet between two adjacent lower through holes, and on the boss between two adjacent lower flow channels.

8. The composite growth base for diamond synthesis according to claim 6, wherein: Each upper through hole, upper flow channel, lower through hole and lower flow channel is fan-shaped.

9. The composite growth base for diamond synthesis according to claim 5, wherein: A stepped groove with the notch facing downward is provided on the molybdenum upper platform, and the stepped groove includes a small-diameter groove on the upper side and a large-diameter groove on the lower side. The upper flow channel is arranged on the bottom wall of the small-diameter groove. The upper welding piece and the middle platform body are both located in the small-diameter groove and their outer diameters are equal to the inner diameter of the small-diameter groove. The middle welding piece and the molybdenum lower platform are both located in the large-diameter groove and their outer diameters are equal to the inner diameter of the large-diameter groove.

10. The composite growth base for diamond synthesis according to any one of claims 1 to 4, characterized in that: The molybdenum lower platform is provided with a lower center hole connected to the stainless steel pipe and a plurality of lower flow channels connected to the lower center hole in a scattered manner. The middle welding plate is provided with a through hole corresponding to the lower center hole for the middle platform pipe to pass through, and a plurality of lower through holes connected to the through holes in a scattered manner. The lower through holes correspond to the lower flow channels one by one and have the same shape. The lower end surface of the middle platform body and the lower through holes and the lower flow channels together form a lower cooling cavity.

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