Vapor deposition densification structure of spherical ultrathin carbon-carbon screen blank

Abstract

The invention discloses a vapor deposition densification structure of a spherical ultrathin carbon-carbon screen blank, and belongs to the technical field of engine design. The vapor deposition densification structure comprises a male die and a female die. The ultrathin carbon-carbon screen blank is fixed through the three bosses on the upper surface of the male die, and the ultrathin carbon-carbon composite material is not subjected to high-temperature thermal deformation in the CVD deposition process through clamping of the male die and the female die. Through the vent holes, the transverse vent grooves and the longitudinal vent grooves machined in the male die and the female die, the ultrathin carbon-carbon screen blank makes full contact with the deposition atmosphere in the CVD deposition process. The method solves the problem that the ultra-thin carbon-carbon screen blank is difficult to fully contact with the deposition atmosphere while high-temperature thermal deformation of the ultra-thin carbon-carbon screen blank is limited.

Description

Technical Field

[0001] This invention relates to a vapor-phase deposition densification structure for a spherical ultrathin carbon screen preform, belonging to the field of engine design technology. Background Technology

[0002] As deep space exploration progresses, traditional chemical propulsion systems are increasingly unable to meet the demands of deep space missions. To address this new challenge, long-life electric propulsion ion engines have become the preferred propulsion system for next-generation spacecraft. Their working principle is as follows: First, electrical energy is used to ionize the propellant. The ionized ions are then accelerated and extracted as they pass through a grid assembly with an ultra-thin screen structure, thereby generating long-lasting stable thrust. The grid assembly is the core component of the electric propulsion ion engine, and its design and manufacturing level directly determines the performance and lifespan of the propulsion system.

[0003] While breakthroughs have been achieved in the manufacturing of conventional molybdenum metal gates, their lifespan is only 14,000 hours, far short of the 40,000-hour lifespan required for deep space exploration. To improve the structural performance of ultra-thin screen-structured gate components, further research into the application of advanced materials is essential. Carbon-carbon composite materials possess advantages such as lightweight, high strength, low expansion, high temperature resistance, and resistance to ion sputtering, making them an ideal alternative to molybdenum metal as a gate component material for electric propulsion ion engines. Ion engines impose strict limitations on the thickness of the gate component. Molybdenum metal gates are generally designed in a planar shape, but carbon-carbon composite materials have weaker impact toughness than molybdenum metal. If the ultra-thin carbon-carbon screen follows a planar design, it will be more prone to brittle fracture than metallic materials when subjected to ion beam impacts. When faced with an impact, the arched surface can distribute the impact load across the entire structural surface, thereby significantly reducing local stress concentration. This load dispersion characteristic allows the arched surface to transmit energy more evenly when subjected to impact and reduces the possibility of fracture. Therefore, in order to improve the impact toughness of ultra-thin carbon screens and ensure their service life, designing the central region as a more impact-resistant convex shape (such as a spherical surface) is a more feasible solution.

[0004] The fabrication process of ultrathin carbon-carbon screen grids can be broadly divided into three main steps: preform forming, CVD (chemical vapor deposition) carbonization, and finishing. Among these, CVD carbonization is a crucial step in improving the carbon content and density of the ultrathin carbon-carbon screen. Given the ultrathin nature of the carbon-carbon screen, directly placing the preform in the deposition furnace for CVD deposition would lead to localized warping and deformation of the carbon-carbon composite sample after cooling. This is because the preform expands under high temperature while the pores are continuously filled with deposited carbon elements, causing a redistribution of thermal stress. To avoid this, a tooling structure must be used to constrain the thermal deformation of the sample during CVD deposition. However, if the preform is completely fitted to the tooling structure, it will not be able to contact the deposition atmosphere, thus preventing CVD deposition. Therefore, a dense tooling structure needs to be designed that can both limit the high-temperature thermal deformation of the sample and ensure sufficient contact between the preform and the deposition atmosphere. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the difficulty of limiting the high-temperature thermal deformation of ultrathin carbon screen blanks while ensuring sufficient contact between them and the deposition atmosphere. A vapor-phase deposition densification structure for spherical ultrathin carbon screen blanks is proposed. Using this structure, vapor-phase deposition densification of ultrathin carbon screen blanks is carried out, and finally, ultrathin carbon composite materials with shape retention and deposition density that meet the design requirements are obtained.

[0006] The technical solution of this invention is: This invention discloses a vapor-phase deposition densification structure for a spherical ultrathin carbon-carbon screen preform, comprising: a male mold, a female mold, a pin, a nut, and a screw; wherein, The female mold and the male mold are disc structures, and multiple grooves and through holes are machined on the edges of both the female mold and the male mold. The pin passes through the through holes of the female mold and the male mold to achieve positioning and alignment; The male mold surface edge presses against the female mold surface edge; the screw passes through the groove of the female mold and the groove of the male mold in sequence and then connects with the nut to fix the female mold and the male mold; Multiple ventilation holes are machined in the middle area of ​​the female mold, and each ventilation hole is a through hole that penetrates the female mold along the thickness direction; The male mold has multiple ventilation holes machined along the vertical surface direction; The ventilation holes of the female mold correspond one-to-one with those of the male mold, and are used to allow the deposition atmosphere to pass through during the CVD deposition process; Multiple longitudinal ventilation grooves are machined along the longitudinal direction on the surface of the female mold, and multiple transverse ventilation grooves are machined along the transverse direction on the upper surface of the female mold; Multiple longitudinal ventilation grooves are machined along the longitudinal direction on the surface of the male mold, and multiple transverse ventilation grooves are machined along the transverse direction on the upper surface of the male mold. The transverse ventilation grooves of the female mold correspond one-to-one with the transverse ventilation grooves of the male mold; the longitudinal ventilation grooves of the female mold correspond one-to-one with the longitudinal ventilation grooves of the male mold, which are used to allow the deposition atmosphere to pass through during the CVD deposition process.

[0007] Furthermore, in the above structure, the distance between vent holes and the distance between the through holes and vent holes of the female mold satisfy the following constraints: L3≥2.5D3; L4≥3D3; L5≥1.5D3 Where L5 is the distance between the through hole and the vent hole of the female mold, L3 is the spacing between the vent hole and the through hole, L4 is the spacing between the vent hole and the row hole, and D3 is the diameter of the vent hole.

[0008] Furthermore, in the above structure, the female mold surface is machined with multiple longitudinal ventilation grooves along the longitudinal direction, and the female mold surface is machined with multiple transverse ventilation grooves along the transverse direction; the middle surface of the longitudinal ventilation groove of the female mold should coincide with the axis of the female mold ventilation hole, and the middle surface of the transverse ventilation groove of the female mold should coincide with the axis of the female mold ventilation hole.

[0009] Furthermore, in the above structure, the dimensions and spacing between the longitudinal venting groove of the female mold, the transverse venting groove of the female mold, and the venting hole of the female mold satisfy the following constraints: L3=L7; L4=L9; L6=L8; L6≤0.7D3; L6≥0.5D3 Where L3 is the spacing between vent holes and parallel holes, L4 is the spacing between vent holes and parallel holes, L6 is the width of the longitudinal vent groove of the female mold, L7 is the spacing between the longitudinal vent grooves of the female mold, L8 is the width of the transverse vent groove of the female mold, L9 is the spacing between the transverse vent grooves of the female mold, and D3 is the diameter of the vent hole.

[0010] Furthermore, in the above structure, the distance between the male mold vent holes and the distance between the male mold through holes and the male mold vent holes satisfy the following constraints: L 14 ≥2.5D3; L 15 ≥3D3; L 16 ≥1.5D3 Among them, L 14 L is the spacing between the vent holes and the parallel holes of the male mold. 15 L is the spacing between the ventilation holes of the male mold. 16 D3 is the distance between the through hole and the vent hole of the male mold, and D3 is the diameter of the vent hole.

[0011] Furthermore, in the above structure, the middle surface of the longitudinal ventilation groove of the male mold coincides with the axis of the male mold ventilation hole, and the middle surface of the transverse ventilation groove of the male mold coincides with the axis of the male mold ventilation hole.

[0012] Furthermore, in the above structure, the dimensions and spacing between the longitudinal venting groove of the male mold, the transverse venting groove of the male mold, and the venting hole of the male mold satisfy the following constraints: L 14 =L 11 ; L 15 =L 13 ; L 10 =L 12 ; L 10 ≤0.7D3; L 10 ≥0.5D3 Among them, L 14 L is the spacing between the vent holes and the parallel holes of the male mold. 15 D3 is the spacing between the rows of vent holes in the male mold, D3 is the diameter of the vent hole, and L is the spacing between the rows of vent holes in the male mold. 10 L is the width of the longitudinal ventilation groove of the male mold. 11 L is the spacing between the longitudinal ventilation slots of the male mold. 12 L is the width of the transverse ventilation groove of the male mold. 13 This refers to the spacing between the transverse ventilation slots of the male mold.

[0013] Furthermore, in the above structure, the male mold surface is machined with a first male mold surface boss, a second male mold surface boss, and a third male mold surface boss; The outer curved edge of the first boss on the surface of the male mold coincides with the edge of the male mold, and the other three boundary lines are the first straight edge, the first curved edge, and the second curved edge, respectively; the outer curved edge of the second boss on the surface of the male mold coincides with the edge of the male mold, and the other three boundary lines are the second straight edge, the third curved edge, and the fourth curved edge, respectively; the outer curved edge of the third boss on the surface of the male mold coincides with the edge of the male mold, and the other three boundary lines are the third straight edge, the fifth curved edge, and the sixth curved edge, respectively; During the CVD deposition process, the edge of the ultrathin carbon screen preform is in close contact with the first curved edge of the first boss edge on the male mold surface, the second curved edge of the second boss edge on the male mold surface, and the third curved edge of the third boss edge on the male mold surface, thereby fixing the ultrathin carbon screen preform.

[0014] Furthermore, in the above structure, there is a circumferential gap between the first boss, the second boss, and the third boss on the male mold surface.

[0015] Furthermore, in the above structure, the hole diameter, row spacing, and hole spacing dimensional parameters between the male and female molds satisfy the following constraints: L 14 =L3; L 15 =L4; L 16 =L5; D3=D6; D4=D7 Where L3 is the spacing between vent holes and parallel vent holes, L4 is the spacing between vent holes and parallel vent holes, L5 is the distance between vent holes and parallel vent holes, and L 14 L is the spacing between the vent holes and the parallel holes of the male mold. 15 L is the spacing between the ventilation holes of the male mold. 16 D6 is the distance between the through hole and the vent hole of the male mold, D7 is the diameter of the vent hole, and D6 is the diameter of the through hole.

[0016] The present invention has the following beneficial effects: This invention employs a vapor deposition densification structure design with venting holes and shaping bosses arranged in a crisscross pattern. Three bosses on the upper surface of the male mold effectively fix the ultrathin carbon-carbon screen preform. The clamping action between the male and female molds restricts the high-temperature thermal deformation of the ultrathin carbon-carbon composite material during CVD deposition. Venting holes, transverse venting grooves, and longitudinal venting grooves machined on the male and female molds ensure sufficient contact between the ultrathin carbon-carbon screen preform and the deposition atmosphere during CVD deposition. By using this structure to restrict the deformation of the ultrathin carbon-carbon screen in the vapor deposition process, no additional step to eliminate thermal deformation is needed in subsequent preparation processes, thus improving the preparation efficiency of the ultrathin carbon-carbon screen. Ultimately, this invention solves the technical problem of simultaneously restricting the high-temperature thermal deformation of the ultrathin carbon-carbon screen preform and ensuring sufficient contact with the deposition atmosphere, thereby improving production efficiency. Attached Figure Description

[0017] Figure 1 This is a top view of the ultrathin carbon screen preform sample according to an embodiment of the present invention. Figure 2 This is a cross-sectional view of section AA of the ultrathin carbon screen blank sample according to an embodiment of the present invention; Figure 3 This is a top view of the negative mold of the vapor-deposited densified structure according to an embodiment of the present invention; Figure 4 This is a cross-sectional view of the BB cross-section of the vapor-deposited densified structure in an embodiment of the present invention. Figure 5 This is a bottom view of the negative mold of the vapor-deposited densified structure according to an embodiment of the present invention; Figure 6 This is a top view of the positive mold of the vapor-deposited densified structure according to an embodiment of the present invention; Figure 7 This is a cross-sectional view of the CC section of the positive mold for the vapor-deposited densified structure according to an embodiment of the present invention; Figure 8 This is a bottom view of the positive mold of the vapor-deposited densified structure according to an embodiment of the present invention; Figure 9 This is a side view of the assembled vapor-deposited densified structure according to an embodiment of the present invention; Figure 10 This is a view of the assembly of a vapor-deposited densified structure according to an embodiment of the present invention, taken from the D direction. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0019] This invention proposes a vapor deposition densification structure for a spherical ultrathin carbon-carbon screen preform. The ultrathin carbon-carbon screen preform is fixed by three protrusions on the upper surface of the male mold. The clamping between the male and female molds prevents the ultrathin carbon-carbon composite material from undergoing high-temperature thermal deformation during CVD deposition. Ventilation holes, transverse ventilation grooves, and longitudinal ventilation grooves machined on the male and female molds ensure sufficient contact between the ultrathin carbon-carbon screen preform and the deposition atmosphere during CVD deposition. This invention solves the problem of limiting the high-temperature thermal deformation of the ultrathin carbon-carbon screen preform while ensuring sufficient contact with the deposition atmosphere.

[0020] The vapor-deposited densification structure in this embodiment is for... Figure 1 The spherical ultrathin carbon screen blank shown is designed.

[0021] like Figure 1 and Figure 2 As shown, the spherical ultrathin carbon screen blank used in this embodiment has a diameter of D1, an edge plane thickness of T1, an upper surface radial width of L1, a lower surface radial width of L2, an upper surface radius of R3, a lower surface radius of R4, a corner radius of R1 on the upper surface of the transition zone between the sphere and the edge plane, and a corner radius of R2 on the lower surface of the transition zone between the sphere and the edge plane.

[0022] like Figure 10 As shown, the vapor-deposited densified structure includes: a male mold 43, a female mold 44, a first pin 41, a second pin 42, a first screw 37, a second screw 38, a third screw 39, a fourth screw 40, a first nut 45, a second nut 46, a third nut 47, and a fourth nut 48.

[0023] The upper surface edge of the male mold 43 presses against the lower surface edge of the female mold 44; two through holes near the edge of the male mold 43 are respectively passed through by the first pin 41 and the second pin 42, and two through holes near the edge of the female mold 44 are respectively passed through by the first pin 41 and the second pin 42, so as to achieve alignment between the male mold 43 and the female mold 44; the first screw 37, the second screw 38, the third screw 39 and the fourth screw 40 all pass through the grooves at the edges of the male mold 43 and the female mold 44, and are respectively connected to the first nut 45, the second nut 46, the third nut 47 and the fourth nut 48, so as to achieve fixation between the male mold 43 and the female mold 44.

[0024] Standard parts can be used for the first pin 41, the second pin 42, the first screw 37, the second screw 38, the third screw 39, the fourth screw 40, the first nut 45, the second nut 46, the third nut 47, and the fourth nut 48.

[0025] like Figure 3 As shown, the female mold 44 has a first groove 1, a second groove 2, a third groove 3 and a fourth groove 4 machined at its edge, which are used for the first screw 37, the second screw 38, the third screw 39 and the fourth screw 40 to pass through respectively; the female mold 44 has a first through hole 5 and a second through hole 6 machined near its edge, which are used for the first pin 41 and the second pin 42 to pass through respectively. The middle area of ​​the female mold 44 is machined with multiple female mold vent holes 9 with a row hole spacing L3 and a row spacing L4. Each vent hole is a through hole that penetrates the female mold along the thickness direction, which is used to allow the deposition atmosphere to pass through during the CVD deposition process.

[0026] The outer diameter of the female mold 44 edge is D2; the diameters of the first through hole 5 and the second through hole 6 are both D4. Based on these dimensions, standard universal pins can be selected, or pins that can be machined to achieve a tight fit with the first through hole 5 and the second through hole 6 can be selected; to ensure that the gas flow rate of all vents in the middle area of ​​the female mold 44 remains as consistent as possible during the CVD deposition process, it is recommended that the diameter of all vents be machined to D3; the height of the female mold edge plane area 10 is T2. For example... Figure 4 As shown.

[0027] To prevent defects such as cracking from occurring during the machining of the female mold 44, the distance between vent holes and the distance between through holes should meet the following constraints: L3≥2.5D3; L4≥3D3; L5≥1.5D3 It should be emphasized that, under the premise of meeting the above constraints, the hole spacing of the negative mold 44 should not be too large in order to improve space utilization and promote CVD deposition.

[0028] like Figure 5As shown, the lower surface of the female mold 44 has multiple longitudinal ventilation grooves 7 with a width of L6 and a spacing of L7, which are used to allow the deposition atmosphere to pass through during the CVD deposition process; the lower surface of the female mold 44 has multiple transverse ventilation grooves 8 with a width of L8 and a spacing of L9, which are used to allow the deposition atmosphere to pass through during the CVD deposition process; according to the shape difference, the lower surface of the female mold 44 is divided into three major areas: the female mold edge plane area 10, the female mold middle curved surface area 11, and the female mold surface transition rounded corner area 12.

[0029] During the CVD deposition process, the upper surface of the spherical ultrathin carbon screen blank comes into contact with the curved surface area 11 in the middle of the female mold, the transition rounded corner area 12 on the surface of the female mold, and part of the flat area 10 on the edge of the female mold. Therefore, the lower surface of the female mold 44 should be processed according to the actual shape and size parameters of the upper surface of the spherical ultrathin carbon screen blank to ensure that the two fit together completely.

[0030] To achieve the ideal CVD deposition effect, the dimensions and spacing between the longitudinal venting groove 7, the transverse venting groove 8, and the venting hole 9 of the female mold should meet the following constraints: L3=L7; L4=L9; L6=L8; L6≤0.7D3; L6≥0.5D3 It should be emphasized that, under the premise of meeting the above constraints, in order to achieve a good synergistic effect among the longitudinal ventilation groove 7, the transverse ventilation groove 8, and the ventilation hole 9 of the female mold 44 during the CVD deposition process, the longitudinal ventilation groove 7 and the transverse ventilation groove 8 of the female mold should both pass through the center of the ventilation hole 9 of the female mold. That is, the middle surface of the longitudinal ventilation groove 7 should coincide with the axis of the ventilation hole 9 of the female mold, and the middle surface of the transverse ventilation groove 8 should coincide with the axis of the ventilation hole 9 of the female mold.

[0031] like Figure 5 and Figure 6 As shown, the upper surface of the male mold 43 has a width of L machined along the longitudinal direction. 10 The spacing is L 11 Multiple longitudinal ventilation grooves 13 of the male mold are used to allow the deposition atmosphere to pass through during the CVD deposition process; the upper surface of the male mold 43 is machined with a width of L along the transverse direction. 12 The spacing is L 13 Multiple transverse ventilation grooves 14 of the male mold are used to allow the deposition atmosphere to pass through during the CVD deposition process; according to the shape difference, the upper surface of the male mold 43 is divided into six major areas: the male mold edge plane area 16, the male mold middle curved surface area 17, the male mold surface transition rounded corner area 18, the male mold surface first boss 19, the male mold surface second boss 23, and the male mold surface third boss 27.

[0032] The outer curved edge of the first boss 19 on the surface of the male mold coincides with the edge of the male mold 43, and the other three boundary lines are the first straight edge 20, the first curved edge 21 and the second curved edge 22, respectively; the outer curved edge of the second boss 23 on the surface of the male mold coincides with the edge of the male mold 43, and the other three boundary lines are the second straight edge 24, the third curved edge 25 and the fourth curved edge 26, respectively; the outer curved edge of the third boss 27 on the surface of the male mold coincides with the edge of the male mold 43, and the other three boundary lines are the third straight edge 28, the fifth curved edge 29 and the sixth curved edge 30, respectively; wherein, the radius value of the first curved edge 21, the third curved edge 25 and the fifth curved edge 29 is R5.

[0033] During the CVD deposition process, the lower surface of the spherical ultrathin carbon screen blank is in contact with the central curved area 17 of the male mold, the transition rounded corner area 18 of the male mold surface, and part of the male mold edge plane area 16. The edge of the ultrathin carbon screen blank is in close contact with the first curved edge 21, the second curved edge 25, and the third curved edge 29. Therefore, the upper surface of the male mold 43 should be processed according to the actual shape and size parameters of the lower surface of the spherical ultrathin carbon screen blank to ensure that the two are completely in contact.

[0034] To ensure good adhesion between the edges of the ultra-thin carbon screen blank and the first curved edge 21, the second curved edge 25, and the third curved edge 29, the following constraints should be met: D1=2R5 It should be emphasized that, in order to achieve the best effect of limiting the high-temperature deformation of the ultrathin carbon-carbon screen preform during the CVD deposition process, it is recommended that the first boss 19, the second boss 23, and the third boss 27 on the male mold surface be designed to be evenly distributed along the circumferential direction. The reason why there is a gap along the circumferential direction between the first boss 19, the second boss 23, and the third boss 27 on the male mold surface instead of occupying the entire edge of the male mold 43 is to facilitate the application of force from the edge of the ultrathin carbon-carbon composite material for demolding after the CVD deposition process is completed.

[0035] To achieve the ideal CVD deposition effect, the dimensions and spacing between the longitudinal venting groove 13, the transverse venting groove 14, and the venting hole 15 of the male mold should meet the following constraints: L 14 =L 11 ; L 15 =L 13 ; L 10 =L 12 ; L 10 ≤0.7D3; L 10 ≥0.5D3 It should be emphasized that, under the premise of meeting the above constraints, in order to achieve a good synergistic effect among the longitudinal ventilation groove 13, the transverse ventilation groove 14, and the ventilation hole 15 of the male mold 44 during the CVD deposition process, the longitudinal ventilation groove 13 and the transverse ventilation groove 14 of the male mold should both pass through the center of the ventilation hole 15 of the male mold. That is, the middle surface of the longitudinal ventilation groove 13 of the male mold should coincide with the axis of the ventilation hole 15 of the male mold, and the middle surface of the transverse ventilation groove 14 of the male mold should coincide with the axis of the ventilation hole 15 of the male mold.

[0036] like Figure 8 As shown, the male mold 43 has a fifth groove 32, a sixth groove 33, a seventh groove 34, and an eighth groove 31 machined at its edge, for the first screw 37, the second screw 38, the third screw 39, and the fourth screw 40 to pass through, respectively; the male mold 43 has a third through hole 36 and a fourth through hole 35 machined near its edge, for the first pin 41 and the second pin 42 to pass through, respectively; the male mold 43 has a row of holes spaced L in the middle area. 14 Line spacing L 15 Multiple male mold vents 15, each vent is a through hole that penetrates the female mold along the thickness direction, used to allow the deposition atmosphere to pass through during the CVD deposition process.

[0037] like Figure 9 As shown, the outer diameter of the male mold 43 is D5; the diameters of the third through hole 36 and the fourth through hole 35 are both D7. Based on these dimensions, standard universal pins can be selected, or pins that can be machined to achieve a tight fit with the third through hole 36 and the fourth through hole 35 can be selected; to ensure that the gas flow rate of all vents in the middle area of ​​the male mold 43 remains as consistent as possible during the CVD deposition process, it is recommended that the diameter of all vents be machined to D6; the height of the male mold edge plane area 16 is T3. Figure 7 As shown.

[0038] To prevent defects such as cracking from occurring during the machining of the male mold 43, the distance between vent holes and the distance between through holes should meet the following constraints: L 14 ≥2.5D3; L 15 ≥3D3; L 16 ≥1.5D3 It should be emphasized that, under the premise of meeting the above constraints, the hole spacing of the male mold 43 should not be too large in order to improve space utilization and promote CVD deposition.

[0039] To ensure that all ventilation holes, longitudinal ventilation grooves, and transverse ventilation grooves machined on the male mold 43 and female mold 44 correspond one-to-one after assembly, the dimensional parameters such as hole diameter, row spacing, and hole spacing between the two molds should meet the following constraints: L 14 =L3; L 15 =L4; L 16 =L5; D3=D6; D4=D7 like Figure 10 As shown, during the assembly of the vapor-deposited densified structure, the first pin 41 passes through the first through hole 5 and the third through hole 36 in sequence, and the second pin 42 passes through the second through hole 6 and the fourth through hole 35 in sequence, thereby aligning the male mold 43 and the female mold 44; the first screw 37 passes through the first groove 1 and the fifth groove 32 in sequence and is connected to the first nut 45; the second screw 38 passes through the second groove 2 and the sixth groove 33 in sequence and is connected to the second nut 46; the third screw 39 passes through the third groove 3 and the seventh groove 34 in sequence and is connected to the third nut 47; and the fourth screw 40 passes through the fourth groove 4 and the eighth groove 31 in sequence and is connected to the fourth nut 48, thereby fixing the male mold 43 and the female mold 44.

[0040] Using the structure proposed in this invention, the CVD deposition process of ultrathin carbon-carbon screen preforms can be achieved by... Figures 3-8 The female and male molds shown are used to fix and limit the ultra-thin carbon screen blank, thereby avoiding the problem of irreversible thermal deformation of the ultra-thin carbon composite material after experiencing high temperature process.

[0041] This invention avoids the problem of insufficient contact between the deposition atmosphere and the ultrathin carbon screen preform due to the limitation of the densified structure of vapor deposition during the CVD deposition process by processing ventilation holes, longitudinal ventilation grooves and transverse ventilation grooves on the lower surface of the female mold, the upper surface of the male mold, the thickness direction of the female mold, and the thickness direction of the male mold according to certain rules.

[0042] The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A structure for vapor deposition densification of a spherical ultra-thin carbon-carbon sieve blank, characterized in that, Comprise: Male die (43), female die (44), pin, nut and screw; wherein, The female die (44) and male die (43) are disc structures, and a plurality of grooves and through holes are processed at the edges of the female die (44) and the male die (43); The pin passes through the through hole of the female die (44) and the through hole of the male die (43), and realizes positioning alignment; The surface edge of the male die (43) is pressed against the surface edge of the female die (44); the screw is connected with the nut after sequentially passing through the groove of the female die and the groove of the male die, and realizes the fixation of the female die (44) and the male die (43); A plurality of female die vent holes (9) are processed in the middle region of the female die (44), and each vent hole (9) is in the form of a through hole penetrating the female die (44) in the thickness direction; A plurality of male die vent holes (15) are processed in the male die (43) in the vertical surface direction; The female die vent hole and the male die vent hole correspond to each other, and are used for passing the deposition atmosphere in the CVD deposition process; A plurality of female die longitudinal vent grooves (7) are processed on the surface of the female die (44) in the longitudinal direction, and a plurality of female die transverse vent grooves (8) are processed on the upper surface of the female die (44) in the transverse direction; A plurality of male die longitudinal vent grooves (13) are processed on the surface of the male die (43) in the longitudinal direction, and a plurality of male die transverse vent grooves (14) are processed on the upper surface of the male die (43) in the transverse direction; The female die transverse vent groove (8) and the male die transverse vent groove (14) correspond to each other; the female die longitudinal vent groove (7) and the male die longitudinal vent groove (13) correspond to each other, and are used for passing the deposition atmosphere in the CVD deposition process.

2. A structure for the densification of a spherical ultra-thin carbon-carbon sieve blank by vapor deposition according to claim 1, characterized in that, The distance between the vent holes (9), the distance between the through hole of the female die and the vent hole (9) satisfy the following constraint conditions: L3≥2.5D3; L4≥3D3; L5≥1.5D3 Wherein, L5 is the distance between the through hole of the female die and the vent hole, L3 is the distance between the vent holes in the same row, L4 is the distance between the vent holes in the same row, and D3 is the diameter of the vent hole.

3. The structure for the densification of a spherical ultra-thin carbon-carbon sieve blank by vapor deposition according to claim 1, characterized in that, A plurality of female die longitudinal vent grooves are processed on the surface of the female die (44) in the longitudinal direction, and a plurality of female die transverse vent grooves are processed on the surface of the female die (44) in the transverse direction; the middle surface of the female die longitudinal vent groove should coincide with the axis of the female die vent hole, and the middle surface of the female die transverse vent groove should coincide with the axis of the female die vent hole.

4. A structure for vapor deposition densification of a spherical ultra-thin carbon-carbon sieve blank according to claim 3, characterized in that, The size and spacing between the female die longitudinal vent groove, the female die transverse vent groove and the female die vent hole satisfy the following constraint conditions: L3=L7; L4=L9; L6=L8; L6≤0.7D3; L6≥0.5D3 Wherein, L3 is the distance between the vent holes in the same row, L4 is the distance between the vent holes in the same row, L6 is the width of the female die longitudinal vent groove, L7 is the spacing of the female die longitudinal vent groove, L8 is the width of the female die transverse vent groove, L9 is the spacing of the female die transverse vent groove, and D3 is the diameter of the vent hole.

5. The structure for the densification of a spherical ultra-thin carbon-carbon sieve blank by vapor deposition according to claim 1, characterized in that, The distance between the vent holes (9), the distance between the through hole of the female die and the vent hole (9) satisfy the following constraint conditions: L 14 ≥2.5D3; L 15 ≥3D3; L 16 ≥1.5D3 wherein L 14 is the distance between the vent holes of the male mold, L 15 is the distance between the vent holes of the male mold, L 16 is the distance between the vent holes of the male mold, D3 is the diameter of the vent holes.

6. The structure for the densification of a spherical ultra-thin carbon-carbon sieve blank by vapor deposition according to claim 1, characterized in that, The middle surface of the female die longitudinal vent groove and the axis of the female die vent hole coincide, and the middle surface of the female die transverse vent groove and the axis of the female die vent hole coincide.

7. A structure for the vapor deposition densification of a spherical ultra-thin carbon-carbon sieve blank according to claim 6, characterized in that, The size and spacing between the female die longitudinal vent groove, the female die transverse vent groove and the female die vent hole satisfy the following constraint conditions: L 14 =L 11 ; L 15 =L 13 ; L 10 =L 12 ; L 10 ≤0.7D3; L 10 ≥0.5D3 wherein L 14 is the distance between the vent holes in a row of vent holes of the male mold, L 15 is the distance between the vent holes in a row of vent holes of the male mold, D3 is the diameter of the vent holes, L 10 is the width of the longitudinal vent grooves of the male mold, L 11 is the distance between the longitudinal vent grooves of the male mold, L 12 is the width of the transverse vent grooves of the male mold, L 13 is the distance between the transverse vent grooves of the male mold.

8. The structure for the densification of a spherical ultra-thin carbon-carbon sieve blank by vapor deposition according to claim 1, characterized in that, The male die (43) is machined with a male die surface first boss (19), a male die surface second boss (23) and a male die surface third boss (27); The outer side curve of the male die surface first boss (19) coincides with the edge of the male die (43), and the other three boundary lines are respectively a first straight edge (20), a first curve edge (21) and a second curve edge (22); the outer side curve of the male die surface second boss (23) coincides with the edge of the male die (43), and the other three boundary lines are respectively a second straight edge (24), a third curve edge (25) and a fourth curve edge (26); the outer side curve of the male die surface third boss (27) coincides with the edge of the male die (43), and the other three boundary lines are respectively a third straight edge (28), a fifth curve edge (29) and a sixth curve edge (30); During the CVD deposition process, the edge of the ultra-thin carbon-carbon screen mesh blank is in close contact with the first curve edge (21) of the edge of the male die surface first boss (19), the second curve edge (22) of the edge of the male die surface second boss (23) and the third curve edge (25) of the edge of the male die surface third boss (27), thereby realizing the fixation of the ultra-thin carbon-carbon screen mesh blank.

9. A structure for the vapor deposition densification of a spherical ultra-thin carbon-carbon sieve blank according to claim 8, characterized in that, A gap is left between the male die surface first boss (19), the male die surface second boss (23) and the male die surface third boss (27) along the ring direction.

10. The structure for the densification of a spherical ultra-thin carbon-carbon sieve blank by vapor deposition according to claim 1, characterized in that, The aperture, row spacing and hole spacing size parameters between the male die and the female die satisfy the following constraint conditions: L 14 =L3; L 15 =L4; L 16 =L5; D3=D6; D4=D7 Wherein, L3 is the distance between the through holes in the same row of the vent holes, L4 is the distance between the rows of the vent holes, L5 is the distance between the through holes and the vent holes, L 14 L3 is the distance between the through holes in the same row of the vent holes, 15 L4 is the distance between the rows of the vent holes, 16 L5 is the distance between the through holes and the vent holes, D6 is the diameter of the vent hole, and D7 is the diameter of the through hole.

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