An apparatus for assisting ceramic precursor impregnation and an impregnation method thereof

Abstract

This invention relates to the field of ceramic matrix composite material preparation technology, specifically to an auxiliary device and method for impregnating ceramic precursors. The device includes a vacuum tank, a filter plate, a filter membrane, an outlet, and a multi-stage condenser. The vacuum tank has a tank body and a matching tank bottom. The tank body is vertically adjustable at the top of the tank bottom via a cylinder. The tank body is equipped with a vacuum extraction port, a liquid injection port, a pressurization port, a vacuum breaking port, and two observation windows. This invention achieves controllable venting during pressurized impregnation by providing a valved outlet at the bottom of the vacuum tank. Opening the valve during the pressurized impregnation stage allows residual gas inside the tank to be discharged, effectively reducing porosity defects inside the preform and improving the density of the composite material. The repeatable venting operation enables a cyclic impregnation effect of "pressurization-venting-repressurization," equivalent to achieving a "pulse pressurization" impregnation effect within a single impregnation cycle, significantly improving impregnation efficiency and uniformity.

Description

Technical Field

[0001] This invention relates to the field of ceramic matrix composite material preparation technology, specifically to an apparatus and method for assisting in the impregnation of ceramic precursors. Background Technology

[0002] Ceramic matrix composites (CMCs) are widely used in aerospace, automotive, and military fields due to their excellent high-temperature resistance, corrosion resistance, and mechanical properties. The precursor impregnation-pyrolysis process (PIP process) is one of the main processes for preparing fiber-reinforced ceramic matrix composites. The general procedure is as follows: a fiber preform is placed in a sealed container and a vacuum is applied. A liquid precursor is injected, which penetrates the preform through capillary force. After impregnation for a certain period, the preform is removed, crosslinked, and cured. Then, it is pyrolyzed at high temperature. This impregnation-crosslinking-pyrolysis process is repeated until a dense composite material is obtained.

[0003] In the PIP (Pressure Injection) process, vacuum pressure impregnation is an important means to improve impregnation efficiency and densification effect. Existing vacuum pressure impregnation equipment typically employs the following steps: placing the fiber preform into a vacuum tank, evacuating the tank, injecting a ceramic precursor solution, and then pressurizing the tank to ensure the precursor fully penetrates the pores within the preform. However, existing equipment has a significant drawback: during the pressurized impregnation stage, the vacuum tank is in a sealed state, making it impossible to release the gas inside. Because the ceramic precursor solution may carry air bubbles during injection and impregnation, or volatile components in the solution may release gas under pressure and temperature changes, these gases become trapped inside the tank and cannot escape, leading to:

[0004] 1. Porous defects are formed inside the preform, affecting the density and mechanical properties of the composite material;

[0005] 2. It hinders the penetration of the precursor solution into the pores inside the preform, resulting in uneven impregnation;

[0006] 3. Reduced impregnation efficiency, requiring multiple impregnation cycles to achieve the target density.

[0007] To address these technical problems, we propose an apparatus and method for assisting in the impregnation of ceramic precursors. Summary of the Invention

[0008] This invention provides the following technical solution: an apparatus for assisting in the impregnation of ceramic precursors, comprising a vacuum tank, the vacuum tank having a tank body and a tank bottom therewith, the tank body being vertically and vertically mounted on the top of the tank bottom via a cylinder, the tank body being provided with a vacuum extraction port, a liquid injection port, a pressurization port, a vacuum breaking port, and two observation windows; the apparatus further includes:

[0009] A filter plate is installed between the bottom of the tank and the tank body, and several through holes are opened on the filter plate;

[0010] The filter membrane, which can be detachably placed above the filter plate, is used to filter the impregnated precursor. The filter plate is used to provide structural support for the fiber preform and the filter membrane.

[0011] The air outlet is located at the bottom of the tank and is connected to the inside of the tank bottom. An exhaust valve is connected after the air outlet to control the opening and closing of the air outlet.

[0012] A multi-stage condensation recovery unit is installed at the end of the exhaust valve to recover precursors and avoid exhaust waste.

[0013] As a preferred embodiment of the present invention, the exhaust valve further includes a control mechanism for controlling opening and closing. The control mechanism includes a control seat fixedly disposed at the bottom of the tank bottom, a sliding seat slidably disposed on one side of the outer periphery of the control seat in a horizontal direction, a rack fixedly disposed at the bottom of the sliding seat, and a gear fixedly disposed at the end of the valve stem of the exhaust valve. The specifications of the gear are adapted to the specifications of the rack. In the initial state, the rack and the gear are not meshed.

[0014] As a preferred embodiment of the present invention, a cylinder is fixedly provided on the side of the control seat away from the sliding seat. A piston and a top tube are slidably provided inside the cylinder. The diameter of the top tube is smaller than that of the piston, and the top tube movably passes through one end of the cylinder and extends to the outside of the cylinder. In the initial state, one end of the top tube abuts against one side of the cylinder. A first spring is also fixedly provided inside the cylinder. The first spring is fixedly provided between one side of the piston and the inner wall of one end of the cylinder.

[0015] As a preferred embodiment of the present invention, a connecting bridge is provided between the end of the outer ring surface of the top tube away from the piston and the sliding seat. A straight groove is provided on the control seat to accommodate the movement of the connecting bridge. A first connector is fixedly provided at the end of the cylinder near the piston. The interior of the first connector communicates with the interior of the cylinder. A second connector is fixedly provided on the air outlet. The interior of the second connector communicates with the interior of the air outlet. An air pipe is fixedly provided between the first connector and the second connector. The air pipe connects the air outlet and the interior of the cylinder through the first connector and the second connector.

[0016] As a preferred embodiment of the present invention, a lever is rotatably provided on one side of the control seat near the cylinder, and a pressure end is bent at one end of the lever near the first connector. The pressure end extends to the top of the cylinder. A locking end is fixedly provided on one side of the lever near the cylinder. The locking end is located on the lever at the end away from the pressure end. A locking groove adapted to the specifications of the locking end is opened at the lower part of the outer ring surface of the top pipe near the connecting bridge.

[0017] As a preferred embodiment of the present invention, a first connecting pin is fixedly provided on the lever, and a second connecting pin is fixedly provided on one side of the control seat near the lever. The second connecting pin is located at the top of the first connecting pin, and a tension spring is fixedly provided between the second connecting pin and the first connecting pin. The tension spring is in an elastic pre-tightened state.

[0018] As a preferred embodiment of the present invention, a through cavity is integrally formed at the top end of the cylinder near the first connector. The inside of the through cavity communicates with the inside of the cylinder. In the initial state, the piston is located at the bottom of the through cavity. An end cap is fixedly provided at the top of the through cavity. A push rod is slidably provided inside the end cap along the axial direction of the through cavity. The push rod extends to the inside and outside of the through cavity. The top of the push rod abuts against the bottom of the pressure end, and a push head is fixedly provided at the bottom of the push rod. The outer wall of the push head slides in contact with the inner wall of the through cavity. In the initial state, the bottom of the push head abuts against the outer ring surface of the piston. The bottom of the push head has a C-shaped chamfer. A second spring is sleeved around the push rod. The second spring is fixedly provided between the end cap and the push head, and in the initial state, the second spring is in an elastic pre-tightened state.

[0019] As a preferred embodiment of the present invention, a limiting ring is fixedly provided at one end of the top tube near the piston, and a third spring is sleeved around the top tube. The third spring is located inside the first spring and is fixedly disposed between the side of the limiting ring and the inner wall of one end of the cylinder.

[0020] As a preferred embodiment of the present invention, the valve stem end of the exhaust valve is fixedly provided with a hand-tightening head for manually opening and closing the exhaust valve.

[0021] An impregnation method for an auxiliary ceramic precursor impregnation device includes the following steps:

[0022] S1. Place the filter membrane at the bottom of the tank, place the fiber preform on top of the filter membrane, close the exhaust valve, assemble the tank bottom and tank body together, and evacuate the vacuum tank through the vacuum port to create a negative pressure inside the vacuum tank.

[0023] S2. Inject the ceramic precursor solution into the vacuum tank through the injection port, so that the precursor solution immerses the fiber preform. Introduce compressed air into the vacuum tank through the pressurization port to create positive pressure inside the vacuum tank for pressurized impregnation.

[0024] S5. During the pressurized impregnation process, open the exhaust valve to release the gas in the vacuum tank through the vent, and then close the exhaust valve.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. This invention achieves controllable venting during the pressurized impregnation process by setting an outlet with a valve at the bottom of the vacuum tank. Opening the valve during the pressurized impregnation stage allows residual gas in the tank (including bubbles released from the precursor solution and residual gas in the fiber preform) to be discharged, effectively reducing porosity defects inside the preform and improving the density of the composite material.

[0027] 2. This invention achieves a cyclic impregnation effect of "pressurization-venting-repressurization" through repeatable venting operations (opening the venting valve to vent and then closing it again to continue pressurizing and impregnating). This is equivalent to achieving an impregnation effect similar to "pulse pressurization" within a single impregnation cycle, which significantly improves impregnation efficiency and uniformity. Attached Figure Description

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

[0029] Figure 2 This is a perspective structural diagram of the vacuum tank in this invention;

[0030] Figure 3 This is a side sectional view of the vacuum tank in this invention;

[0031] Figure 4 In this invention Figure 3 A partial structural diagram;

[0032] Figure 5 This is a schematic diagram of the control mechanism in the present invention. Figure 1 ;

[0033] Figure 6 This is a schematic diagram of the control mechanism in the present invention. Figure 2 ;

[0034] Figure 7 This is a side sectional view of the cylinder in this invention;

[0035] Figure 8 In this invention Figure 7 A partial structural diagram.

[0036] In the diagram: 100, tank body; 200, tank bottom; 300, filter plate; 400, filter membrane; 500, air outlet; 600, exhaust valve; 601, control seat; 602, sliding seat; 603, rack; 604, gear; 605, cylinder; 606, piston; 607, top pipe; 608, connecting bridge; 6001, straight groove; 609, first connector; 6010, second connector; 6011, air pipe; 6012, first spring; 6013, lever; 6014, pressure end; 6 015. Locking end; 6016. Locking slot; 6017. First connecting pin; 6018. Second connecting pin; 6019. Tension spring; 6020. Through cavity; 6021. End cap; 6022. Push rod; 6023. Second spring; 6024. Push head; 6025. Limiting ring; 6026. Third spring; 6027. Hand-tightening head; 700. Multi-stage condenser recovery unit; 101. Vacuum port; 102. Liquid injection port; 103. Pressurization port; 104. Vacuum breaking port; 105. Observation window. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Please see Figures 1 to 8 The technical solution provided by the present invention specifically includes the following embodiments:

[0039] An apparatus for impregnating ceramic precursors includes a vacuum tank, which has a tank body 100 and a matching tank bottom 200. The tank body 100 is vertically adjustable at the top of the tank bottom 200 via a cylinder. The tank body 100 is provided with a vacuum extraction port 101, a liquid injection port 102, a pressurization port 103, a vacuum breaking port 104, and two observation windows 105. The device also includes: a filter plate 300, disposed between the tank bottom 200 and the tank body 100, with several through holes; a filter membrane 400, detachably placed above the filter plate 300, used to filter the impregnated precursor, with the filter plate 300 providing structural support for the fiber preform and the filter membrane 400; an exhaust port 500, located at the bottom of the tank bottom 200 and communicating with the interior of the tank bottom 200, with an exhaust valve 600 connected after the exhaust port 500, used to control the opening and closing of the exhaust port 500; and a multi-stage condensation recovery machine 700, located at the tail end of the exhaust valve 600, used for the recovery of the precursor to avoid exhaust waste.

[0040] Specific implementation method: Place the fiber preform above the filter membrane 400 in the vacuum tank, close the exhaust valve 600, start the vacuum pump, and evacuate the vacuum tank through the vacuum port 101 to a vacuum degree ≤100Pa. Maintain for 20 minutes to fully remove the air in the pores of the preform. Then, open the liquid injection port 102 and inject the ceramic precursor solution (such as polycarbosilane PCS solution) into the vacuum tank so that the precursor solution completely immerses the fiber preform.

[0041] Next, the vacuum port 101, liquid injection port 102, and vacuum breaking port 104 are closed. Compressed air is introduced into the vacuum tank through the pressurization port 103 and pressurized to 0.5 MPa for pressurized impregnation. During the pressurized impregnation process, the control mechanism is used to open the exhaust valve 600 once every certain period of time and keep it open for a period of time to discharge the gas accumulated in the tank. Then the exhaust valve 600 is closed and pressurized impregnation continues. After holding the temperature and pressure for 60 minutes, the exhaust valve 600 is opened to release the pressure and discharge the precursor solution. The impregnated preform is taken out and crosslinked and cured at 200℃ for 2 hours. Then it is pyrolyzed at 1200℃ in an argon atmosphere for 1 hour. The weight gain and density are calculated by weighing.

[0042] For further details, please refer to [link / reference]. Figure 5 , Figure 6 As shown:

[0043] The exhaust valve 600 also includes a control mechanism for controlling its opening and closing. This control mechanism includes a control seat 601 fixedly installed at the bottom of the tank bottom 200. A sliding seat 602 is slidably installed on one side of the control seat 601 in a horizontal direction. A rack 603 is fixedly installed at the bottom of the sliding seat 602. A gear 604 is fixedly installed at the end of the valve stem of the exhaust valve 600. The specifications of the gear 604 are compatible with the specifications of the rack 603. In the initial state, the rack 603 and the gear 604 are not meshed. Specifically, when the sliding seat 602 slides horizontally toward the gear 604, the rack 603 will gradually move to the position where it meshes with the gear 604. Continued sliding will drive the gear 604 to rotate, thereby driving the valve stem of the exhaust valve 600 to rotate, realizing the automatic opening of the exhaust valve 600. The exhaust action can be automatically completed during the pressurized impregnation stage without manual operation, improving the automation level of the device operation.

[0044] For further details, please refer to [link / reference]. Figure 5 , Figure 6 , Figure 7 , Figure 8 As shown:

[0045] A cylinder 605 is fixedly mounted on the side of the control seat 601 away from the sliding seat 602. A piston 606 and a top tube 607 are slidably mounted inside the cylinder 605. The diameter of the top tube 607 is smaller than the diameter of the piston 606, and the top tube 607 movably passes through one end of the cylinder 605 and extends to the outside of the cylinder 605. In the initial state, one end of the top tube 607 abuts against one side of the cylinder 605. A first spring 6012 is also fixedly mounted inside the cylinder 605, between one side of the piston 606 and the inner wall of one end of the cylinder 605. The end of the outer circumference of the top tube 607 away from the piston 606 is adjacent to the sliding seat 602. A connecting bridge 608 is provided between the cylinder and the piston 606. A straight groove 6001 is provided on the control seat 601 to accommodate the movement of the connecting bridge 608. A first connector 609 is fixedly provided at one end of the cylinder 605 near the piston 606. The interior of the first connector 609 is connected to the interior of the cylinder 605. A second connector 6010 is fixedly provided on the air outlet 500. The interior of the second connector 6010 is connected to the interior of the air outlet 500. An air pipe 6011 is fixedly provided between the first connector 609 and the second connector 6010. The air pipe 6011 connects the air outlet 500 with the interior of the cylinder 605 through the first connector 609 and the second connector 6010.

[0046] Specifically, when the pressure inside the vacuum tank increases, high-pressure gas enters the cylinder 605 through the outlet 500, the second connector 6010, the air pipe 6011, and the first connector 609. This pushes the piston 606 to overcome the elastic force of the first spring 6012 and move away from the first connector 609. The piston 606 drives the top tube 607 to move synchronously. The top tube 607 drives the sliding seat 602 to slide horizontally towards the gear 604 through the connecting bridge 608. This causes the rack 603 to mesh with the gear 604, which in turn drives the exhaust valve 600 to open automatically. This achieves the purpose of automatically opening the exhaust valve 600 using the high pressure inside the tank itself, without the need for additional power. The structural design is ingenious and energy-saving. When the gas inside the tank is discharged, the pressure inside the tank decreases, and the elastic force of the first spring 6012 pushes the piston 606 to return to its original position.

[0047] For further details, please refer to [link / reference]. Figure 6 , Figure 7 As shown:

[0048] A lever 6013 is rotatably mounted on the side of the control base 601 near the cylinder 605. A pressure end 6014 is bent at the end of the lever 6013 near the first connector 609, extending to the top of the cylinder 605. A locking end 6015 is fixedly mounted on the side of the lever 6013 near the cylinder 605, located at the end of the lever 6013 away from the pressure end 6014. The lower part of the outer circumference of the jacking pipe 607 near the connecting bridge 608... A slot 6016 adapted to the specifications of the card end 6015 is provided. A first connecting pin 6017 is fixedly provided on the lever 6013. A second connecting pin 6018 is fixedly provided on the side of the control seat 601 near the lever 6013. The second connecting pin 6018 is located on top of the first connecting pin 6017, and a tension spring 6019 is fixedly provided between the second connecting pin 6018 and the first connecting pin 6017. The tension spring 6019 is in an elastic pre-tightened state.

[0049] Specifically, when the jacking tube 607 is pushed to the designed maximum stroke position by the piston 606, under the elastic preload of the tension spring 6019, the locking end 6015 is locked into the locking groove 6016 on the outer ring surface of the jacking tube 607, fixing the jacking tube 607 at the maximum stroke position. This ensures that the exhaust valve 600 remains stably open, preventing the third spring 6026 from prematurely resetting the jacking tube 607 after the pressure inside the tank decreases, ensuring that the gas accumulated inside the tank can be fully discharged, and improving the exhaust effect.

[0050] For further details, please refer to [link / reference]. Figure 8 As shown:

[0051] A through cavity 6020 is integrally formed at the top end of cylinder 605 near the first connector 609. The interior of the through cavity 6020 communicates with the interior of cylinder 605. In the initial state, piston 606 is located at the bottom of through cavity 6020. An end cap 6021 is fixedly installed at the top of through cavity 6020. A push rod 6022 is slidably installed inside end cap 6021 along the axial direction of through cavity 6020. The push rod 6022 extends into and out of through cavity 6020. The top of push rod 6022 abuts against the bottom of pressure end 6014, and a push head 6024 is fixedly installed at the bottom of push rod 6022. The outer wall of push head 6024 slides in contact with the inner wall of through cavity 6020. In the initial state, the push head 6024... The bottom of the push head 6024 abuts against the outer ring surface of the piston 606. The bottom of the push head 6024 has a C-shaped chamfer. The push rod 6022 is surrounded by a second spring 6023. The second spring 6023 is fixedly disposed between the end cap 6021 and the push head 6024. In the initial state, the second spring 6023 is in an elastic pre-tightened state. The outer end of the top tube 607 near the piston 606 is fixedly provided with a limit ring 6025. The outer end of the top tube 607 is surrounded by a third spring 6026. The third spring 6026 is located inside the first spring 6012. The third spring 6026 is fixedly disposed between the side of the limit ring 6025 and the inner wall of one end of the cylinder 605.

[0052] Specifically, during the process of the air pressure pushing the piston 606 and the top tube 607 to slide away from the first joint 609, after the piston 606 moves and is misaligned with the push head 6024, the pre-tightened second spring 6023 releases its rebound force, pushing the push head 6024 and the top rod 6022 to move downward. The pre-tightened tension spring 6019 releases its rebound force, driving the lever 6013 and the pressure end 6014 to rotate, so that the bottom of the pressure end 6014 always abuts against the top of the top rod 6022. During the rotation of the lever 6013, the locking end 6015 moves upward by a certain stroke, so that it can be accurately locked into the locking groove 6016.

[0053] After the gas inside the tank is discharged for a period of time, the pressure in cylinder 605 decreases, and the internal air pressure in cylinder 605 decreases synchronously. At this time, the rebound force of the first spring 6012 pushes the piston 606 to reset. As the piston 606 gradually moves back to its initial position, it pushes the push head 6024 and the push rod 6022 upward. The push rod 6022 pushes the pressure end 6014 to rotate upward, and through the lever 6013, it drives the locking end 6015 to move downward for a certain distance, so that the locking end 6015 is disengaged from the locking groove 6016, releasing the lock on the top tube 607. The top tube 607 is quickly reset under the push of the third spring 6026, causing the sliding seat 602 to slide in the opposite direction. Under the meshing of the rack 603 and the gear 604, the exhaust valve 600 automatically closes, completing one automatic exhaust process. There is no need for manual repeated operation of the exhaust valve 600. During the pressurized impregnation process, the gas accumulated in the tank can be automatically discharged periodically, avoiding the gas from hindering the penetration of the precursor solution and ensuring the uniformity of impregnation.

[0054] The valve stem end of the exhaust valve 600 is fixedly equipped with a hand-tightening head 6027 for manually opening and closing the exhaust valve 600. When the automatic exhaust mechanism of the device malfunctions or the device needs to be manually adjusted, the valve stem can be directly rotated by turning the hand-tightening head 6027 to manually control the opening and closing state of the exhaust valve 600, thereby improving the flexibility of device operation and facilitating device maintenance.

[0055] Working principle: Place the fiber preform above the filter membrane 400 inside the vacuum tank, close the exhaust valve 600, start the vacuum pump, and evacuate the vacuum tank through the vacuum port 101 until the vacuum degree is ≤100Pa of the tank body. Maintain this for 20 minutes to fully expel the air from the pores of the preform. Then, open the injection port 102 and inject a ceramic precursor solution, such as polycarbosilane (PCS) solution, into the vacuum tank, ensuring that the precursor solution completely submerges the fiber preform. Next, close the vacuum port 101, injection port 102, and vacuum breaking port 104, and pressurize the vacuum tank through the pressurization port 103. Compressed air and pressurized to 0.5 MPa for pressure impregnation. During the pressure impregnation process, the control mechanism opens the exhaust valve 600 once every certain period of time and keeps it open for a period of time to release the gas accumulated in the tank. Then, the exhaust valve 600 is closed and pressure impregnation continues. After holding the temperature and pressure for 60 minutes, the exhaust valve 600 is opened to release the pressure and discharge the precursor solution. The impregnated preform is taken out and crosslinked and cured at 200℃ for 2 hours. Then, it is pyrolyzed at 1200℃ in an argon atmosphere for 1 hour. The weight gain and density are calculated by weighing.

[0056] The specific working principle is as follows: Compressed air is introduced into the vacuum tank through the pressurization port 103, increasing the air pressure inside the vacuum tank. This pressure acts on the filter membrane 400 and the fiber preform, and is transmitted downwards, passing through the through-holes of the filter plate 300 into the tank bottom 200. It then enters the cylinder 605 through the air outlet 500, the second connector 6010, the air pipe 6011, and the first connector 609. The air pressure pushes the piston 606 and the top pipe 607 to slide away from the first connector 609. The top pipe 607 drives the bridging connecting bridge 608 to move synchronously, and the connecting bridge 608 drives the sliding seat 602, which is slidably mounted on the control seat 601, to move in the same direction. After sliding a certain distance, the rack 603 at the bottom of the sliding seat 602 meshes with the gear 604, driving the valve stem to rotate and open the exhaust valve 600, thus automatically discharging the gas accumulated in the tank. After the piston 606 moves and is misaligned with the push head 6024, the pre-tightened second spring 6023 releases its rebound force, pushing the push head 6024 and the push rod 6022 downward. The pre-tightened tension spring 6019 releases its rebound force, driving the lever 6013 and the pressure end 6014 to rotate, so that the bottom of the pressure end 6014 always abuts against the top of the push rod 6022. During the rotation of the lever 6013, the locking end 6015 moves upward a certain distance.

[0057] Finally, when the jacking tube 607 is pushed to its designed maximum stroke position by the piston 606, the locking end 6015 engages inside the jacking tube 607, preventing it from resetting and keeping the exhaust valve 600 open to ensure that the gas inside the tank can be fully discharged. After the gas inside the tank has been discharged for a period of time, the pressure inside the tank decreases, and the gas pressure inside the cylinder 605 decreases synchronously. At this time, the rebound force of the first spring 6012 pushes the piston 606 to reset. As the piston 606 gradually moves back to its initial position, it pushes the push head 6024 and the push rod 6022 upwards, and the push rod 6022 pushes the pressure end 6014 downwards. The tube rotates upwards, and through lever 6013, it drives the locking end 6015 to move downwards by a certain stroke, causing the locking end 6015 to disengage from the locking groove 6016, releasing the lock on the top tube 607. The top tube 607 is quickly reset under the push of the third spring 6026, causing the sliding seat 602 to slide in the opposite direction. Under the meshing of rack 603 and gear 604, the exhaust valve 600 automatically closes, completing one automatic exhaust process. There is no need for manual repeated operation of the exhaust valve 600. During the pressurized impregnation process, the gas accumulated in the tank can be automatically discharged periodically, avoiding the gas from hindering the penetration of the precursor solution and ensuring the uniformity of impregnation.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. An apparatus for assisting in the impregnation of ceramic precursors, comprising a vacuum tank, a filter plate (300), a filter membrane (400), an air outlet (500), and a multi-stage condenser (700), characterized in that: The vacuum tank has a tank body (100) and a tank bottom (200) that cooperates with it. The tank body (100) is raised and lowered at the top of the tank bottom (200) by a cylinder. The tank body (100) is provided with a vacuum port (101), a liquid injection port (102), a pressurization port (103), a vacuum breaking port (104), and two observation windows (105). The filter plate (300) is located between the tank bottom (200) and the tank body (100), and several through holes are opened on the filter plate (300); The filter membrane (400) is detachably placed above the filter plate (300) for filtering the impregnated precursor. The filter plate (300) provides structural support for the fiber preform and the filter membrane (400). The air outlet (500) is located at the bottom of the tank bottom (200) and is connected to the inside of the tank bottom (200). The air outlet (500) is connected to the exhaust valve (600), which is used to control the opening and closing of the air outlet (500). A multi-stage condensation recovery unit (700) is located at the tail end of the exhaust valve (600) for the recovery of precursors, thus avoiding exhaust waste.

2. The apparatus for assisting in the impregnation of ceramic precursors according to claim 1, characterized in that: The exhaust valve (600) also includes a control mechanism for controlling its opening and closing. The control mechanism includes a control seat (601) fixedly disposed at the bottom of the tank bottom (200). A sliding seat (602) is slidably disposed on one side of the outer periphery of the control seat (601) in the horizontal direction. A rack (603) is fixedly disposed at the bottom of the sliding seat (602). A gear (604) is fixedly disposed at the end of the valve stem of the exhaust valve (600). The specifications of the gear (604) are adapted to the specifications of the rack (603). In the initial state, the rack (603) and the gear (604) are not meshed.

3. The apparatus for assisting in the impregnation of ceramic precursors according to claim 2, characterized in that: A cylinder (605) is fixedly installed on the side of the control seat (601) away from the sliding seat (602). A piston (606) and a top tube (607) are slidably installed inside the cylinder (605). The diameter of the top tube (607) is smaller than that of the piston (606), and the top tube (607) moves through one end of the cylinder (605) and extends to the outside of the cylinder (605). In the initial state, one end of the top tube (607) is in contact with one side of the cylinder (605). A first spring (6012) is also fixedly installed inside the cylinder (605). The first spring (6012) is fixedly installed between one side of the piston (606) and the inner wall of one end of the cylinder (605).

4. The apparatus for assisting in the impregnation of ceramic precursors according to claim 3, characterized in that: A connecting bridge (608) is connected between the outer ring surface of the top tube (607) away from the piston (606) and the sliding seat (602). A straight groove (6001) is provided on the control seat (601) to accommodate the movement of the connecting bridge (608). A first connector (609) is fixedly provided at the end of the cylinder (605) near the piston (606). The interior of the first connector (609) is connected to the interior of the cylinder (605). A second connector (6010) is fixedly provided on the air outlet (500). The interior of the second connector (6010) is connected to the interior of the air outlet (500). An air pipe (6011) is fixedly provided between the first connector (609) and the second connector (6010). The air pipe (6011) connects the air outlet (500) and the interior of the cylinder (605) through the first connector (609) and the second connector (6010).

5. The apparatus for assisting in the impregnation of ceramic precursors according to claim 4, characterized in that: A lever (6013) is rotatably provided on one side of the control seat (601) near the cylinder (605). A pressure end (6014) is bent at one end of the lever (6013) near the first connector (609). The pressure end (6014) extends to the top of the cylinder (605). A locking end (6015) is fixedly provided on one side of the lever (6013) near the cylinder (605). The locking end (6015) is located on the lever (6013) at the end away from the pressure end (6014). A slot (6016) that matches the specifications of the locking end (6015) is opened at the lower part of the outer ring surface of the top tube (607) near the connecting bridge (608).

6. The apparatus for assisting in the impregnation of ceramic precursors according to claim 5, characterized in that: A first connecting pin (6017) is fixedly provided on the lever (6013), and a second connecting pin (6018) is fixedly provided on one side of the control seat (601) near the lever (6013). The second connecting pin (6018) is located on top of the first connecting pin (6017), and a tension spring (6019) is fixedly provided between the second connecting pin (6018) and the first connecting pin (6017). The tension spring (6019) is in an elastic pre-tightened state.

7. The apparatus for assisting in the impregnation of ceramic precursors according to claim 6, characterized in that: The cylinder (605) has an integral cavity (6020) at one end near the first connector (609). The cavity (6020) communicates with the cylinder (605). In the initial state, the piston (606) is located at the bottom of the cavity (6020). An end cap (6021) is fixedly installed on the top of the cavity (6020). A push rod (6022) is slidably installed inside the end cap (6021) along the axial direction of the cavity (6020). The push rod (6022) extends into and out of the cavity (6020). The top of the push rod (6022) is connected to the pressure end (6014). The bottom of the push rod (6022) is in contact with the piston (606), and the bottom of the push rod (6022) is fixedly provided with a push head (6024). The outer wall of the push head (6024) slides in contact with the inner wall of the cavity (6020). In the initial state, the bottom of the push head (6024) is in contact with the outer ring surface of the piston (606). The bottom of the push head (6024) has a C-shaped chamfer. The push rod (6022) is surrounded by a second spring (6023). The second spring (6023) is fixedly provided between the end cap (6021) and the push head (6024). In the initial state, the second spring (6023) is in an elastic pre-tightened state.

8. The apparatus for assisting in the impregnation of ceramic precursors according to claim 7, characterized in that: A limiting ring (6025) is fixedly provided at one end of the top tube (607) near the piston (606), and a third spring (6026) is sleeved around the top tube (607). The third spring (6026) is located inside the first spring (6012), and the third spring (6026) is fixedly provided between the side of the limiting ring (6025) and the inner wall of one end of the cylinder (605).

9. The apparatus for assisting in the impregnation of ceramic precursors according to claim 8, characterized in that: The valve stem end of the exhaust valve (600) is fixedly provided with a hand-tightening head (6027) for manually opening and closing the exhaust valve (600).

10. The impregnation method of the apparatus for assisting in the impregnation of ceramic precursors according to claim 9, characterized in that: The following usage steps are included: S1. Place the filter membrane (400) at the bottom of the tank (200), place the fiber preform above the filter membrane (400), close the exhaust valve (600), assemble the bottom of the tank (200) and the tank body (100) together, and evacuate the vacuum tank through the vacuum port (101) to form a negative pressure inside the vacuum tank. S2. Inject ceramic precursor solution into the vacuum tank through injection port (102) so that the precursor solution immerses the fiber preform. Introduce compressed air into the vacuum tank through pressurization port (103) to create positive pressure in the vacuum tank for pressurized impregnation. S3. During the pressurized impregnation process, open the exhaust valve (600) to release the gas in the vacuum tank through the air outlet (500), and then close the exhaust valve (600).

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