A vacuum pressure impregnation mold and method

Abstract

The present invention provides a mold and method for vacuum pressure impregnation, and belongs to the technical field of vacuum pressure impregnation. The mold for vacuum pressure impregnation of the present invention comprises a bottom plate, a pressurized tank body, a pressurized plate, a pressurized rod, an upper cover plate, a threaded sleeve and a positioning plate; the bottom plate and the pressurized tank body are fixedly connected, and the pressurized tank body is provided with a vacuum port and a slurry port; when the sample to be impregnated is pre-vacuumed, the positioning plate is fixed to the pressurized plate and the pressurized plate is clamped at the upper end of the pressurized tank body; after the pre-vacuuming of the sample to be impregnated is completed, the positioning plate is removed, the pressurized plate and the pressurized rod are fixed, the upper cover plate and the pressurized tank body are fixed, the pressurized rod passes through the upper cover plate and is threadedly connected with the threaded sleeve, the threaded sleeve is used for guiding the pressurized rod, and the interior of the tank body is a closed space after assembly. The method for vacuum pressure impregnation of the present invention uses a press machine to apply pressure to the mold through the pressurized rod, avoids the use of compressed air or inert gas for pressurization, reduces costs, and is suitable for mass production.

Description

Technical Field

[0001] The invention belongs to the technical field of vacuum pressure impregnation, and in particular relates to a vacuum pressure impregnation mold and a method. Background Art

[0002] Fiber reinforced silicon carbide ceramic matrix composites have many advantages such as high strength, high modulus, high thermal conductivity, low thermal expansion coefficient, good fracture toughness, etc. They are widely used in aerospace, nuclear energy, automobile, chemical and other fields.

[0003] Slurry impregnation and precursor impregnation are one of the commonly used methods for preparing fiber-reinforced silicon carbide ceramic matrix composites. The atmospheric pressure impregnation method is limited by factors such as the viscosity of the slurry and ceramic precursor, as well as the wettability with the fiber preform, and it is difficult to fully impregnate the fiber preform. The vacuum pressure impregnation method can achieve full impregnation of the slurry or ceramic precursor into the fiber preform.

[0004] The principle of vacuum pressure impregnation is to pre-evacuate the workpiece and then fill it with the impregnant, and then apply a certain pressure to allow the impregnant to fully penetrate into the pores inside the workpiece, thereby completing the impregnation process. Common vacuum pressure impregnation equipment consists of many parts, and compressed air or inert gas is often used for pressurization. However, this method has high requirements for equipment, the equipment is relatively complex, and the investment cost is high; the impregnant needs to pass through a long impregnant pipeline, which easily causes waste of the impregnant; when changing the impregnant, the impregnation pipeline, impregnation tank, return pipeline, etc. need to be cleaned. The above factors make this equipment only suitable for mass production of products, and not suitable for development and testing of small and medium-sized samples. Summary of the invention

[0005] Therefore, the present invention aims at the problems existing in the existing vacuum pressure impregnation equipment, proposes a vacuum pressure impregnation mold to realize vacuum pressure impregnation of small and medium-sized samples, and also provides a vacuum pressure impregnation method.

[0006] To achieve the above object, the present invention provides a vacuum pressure impregnation mold, comprising a bottom plate, a pressurized tank, a pressurized plate, a pressurized rod, an upper cover plate, a threaded sleeve and a positioning plate;

[0007] The bottom plate is fixedly connected to the pressurized tank body and is used to place the sample to be impregnated; the pressurized tank body is provided with a vacuum port and a slurry port, the vacuum port is connected to a vacuum pump through a rubber tube, and the slurry port is connected to a controllable impregnating agent pipeline with a switch;

[0008] The size of the positioning plate is larger than that of the pressurized tank body. When the sample to be impregnated is pre-vacuumed, the positioning plate is fixed to the pressurized plate and clamps the pressurized plate at the upper end of the pressurized tank body to prevent the pressurized plate from moving downward due to the pressure difference between the inside and outside of the tank body during this process;

[0009] After the pre-vacuuming of the impregnated sample is completed, the positioning plate is removed, the pressure plate and the pressure rod are fixed, the upper cover plate and the pressurized tank body are fixed, the pressure rod passes through the upper cover plate and is threadedly connected with the threaded sleeve, the threaded sleeve is used to guide the pressure rod, and the interior of the tank body is a closed space after assembly.

[0010] Preferably, sealing rings are provided at the threads of the pressurizing plate and the pressurizing rod, respectively, and sealing gaskets are provided between the pressurizing tank body and the bottom plate and the upper cover plate, respectively.

[0011] Preferably, all sealing rings and sealing gaskets are made of fluororubber.

[0012] Preferably, the pressurized tank body is fixedly connected to the bottom plate and the upper cover plate respectively by countersunk screws, the pressurized plate is fixedly connected to the positioning plate by countersunk screws, and the pressurized plate is fixedly connected to the pressurized rod by countersunk screws.

[0013] Preferably, the position of the vacuum port is higher than the position of the slurry port to avoid the slurry being drawn into the vacuum pipeline during the vacuuming process.

[0014] Preferably, the material of the upper cover plate and the threaded sleeve is independently selected from polytetrafluoroethylene or nylon.

[0015] Preferably, the materials of the bottom plate, the pressurized tank body and the pressurized plate are independently selected from 304 or 316 stainless steel.

[0016] Preferably, the pressure rod and the positioning plate are made of quenched 45 steel.

[0017] The present invention also provides a method for vacuum pressure impregnation using the mold as described above, comprising the following steps:

[0018] The bottom plate is fixedly connected to the pressurized tank body, the pressurized plate is fixedly connected to the positioning plate, the pressurized plate is placed inside the pressurized tank body after the sample to be impregnated is placed in the tank body, the vacuum port is connected to the vacuum pump through a rubber tube, and the slurry port is connected to a controllable impregnating agent pipeline with a switch;

[0019] The impregnating agent pipeline is controlled to be in a closed state, the vacuum pump is turned on, and the sample to be impregnated is pre-vacuumed, and the gas retained in the pores of the sample to be impregnated is completely pumped out and then the vacuum pump is turned off;

[0020] The impregnating agent pipeline is controlled to be in an open state, so that the impregnating agent enters the tank body under the action of atmospheric pressure, and the impregnating agent pipeline is controlled to be in a closed state after the impregnating agent in the tank body reaches a certain amount; the liquid level of the impregnating agent in the tank body is controlled to be lower than the position of the slurry port;

[0021] Remove the positioning plate, and connect the pressure rod, the upper cover plate and the threaded sleeve in sequence;

[0022] Turn on the vacuum pump, evacuate the inside of the tank, and then turn off the vacuum pump;

[0023] The mold is placed under a press, the press is in contact with the pressurizing rod, the press is turned on, and pressure is applied to the mold to achieve a vacuum pressure infusion molding process for the sample.

[0024] Preferably, quantitative pressure impregnation of the sample is achieved by controlling the pressure applied by the press to the mold and thereby controlling the pressure of vacuum impregnation inside the tank body; the pressure of vacuum impregnation inside the tank body is calculated by the indication of the pressure gauge on the press.

[0025] The advantages of the present invention using the above technical solution are:

[0026] The vacuum pressure impregnation mold of the present invention comprises a bottom plate, a pressurized tank body, a pressurized plate, a pressurized rod, an upper cover plate, a threaded sleeve, and a positioning plate. The pressurized plate directly pressurizes the liquid surface of the impregnant, and the liquid impregnant is used to transmit pressure so that the impregnant is fully impregnated into the internal pores of the sample to be impregnated. The press applies pressure to the mold through the pressurized rod. The mold is simple, avoiding the use of compressed air or inert gas for pressurization, and reducing the equipment cost. The mold can be designed according to the commonly used size of the sample to avoid the waste of the impregnant. The vacuum pressure impregnation mold of the present invention performs a method for vacuum pressure impregnation. The impregnant can be switched by replacing the impregnant pipeline or using a disposable impregnant pipeline. The mold has wide applicability and is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a schematic diagram of the installation of the positioning plate in the vacuum pressure impregnation mold of the present invention;

[0029] Figure 2 It is a schematic diagram of the installation of the pressure rod in the vacuum pressure impregnation mold of the present invention;

[0030] Figure 3 This is a physical picture of the carbon fiber reinforced silicon carbide preform obtained after impregnation with silicon carbide slurry in Example 1 of the present invention;

[0031] Description of the drawings: 1-bottom plate; 2-pressurized tank body; 3-pressurized plate; 4-pressurized rod; 5-upper cover plate; 6-threaded sleeve; 7-sealing ring; 8-sealing gasket; 9-sealing ring; 10-sealing gasket; 11-positioning plate. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] like Figure 1 and 2 As shown, the present invention provides a vacuum pressure impregnation mold, comprising a bottom plate 1, a pressurized tank body 2, a pressurized plate 3, a pressurized rod 4, an upper cover plate 5, a threaded sleeve 6 and a positioning plate 11;

[0034] The bottom plate 1 and the pressurized tank body 2 are fixedly connected and used to place the sample to be impregnated; the pressurized tank body 2 is provided with a vacuum port and a slurry port, the vacuum port is connected to a vacuum pump through a rubber tube, and the slurry port is connected to a controllable impregnating agent pipeline with a switch;

[0035] The size of the positioning plate 11 is larger than that of the pressurized tank body 2. When the sample to be impregnated is pre-vacuumed, the positioning plate 11 is fixed to the pressurized plate 3 and the pressurized plate 3 is clamped at the upper end of the pressurized tank body 2 to prevent the pressurized plate 3 from moving downward due to the pressure difference between the inside and outside of the tank body and affecting the subsequent pressurization.

[0036] After the pre-vacuuming of the impregnated sample is completed, the positioning plate 11 is removed, the pressure plate 3 and the pressure rod 4 are fixed, the upper cover plate 5 and the pressurized tank body 2 are fixed, the pressure rod 4 passes through the upper cover plate 5 and is threadedly connected with the threaded sleeve 6, and the threaded sleeve 6 is used to guide the pressure rod 4. After assembly, the interior of the tank body is a closed space.

[0037] Among them, sealing rings 7 and 9 can be respectively provided at the threads of the pressurizing plate 3 and the pressurizing rod 4, and sealing gaskets 8 and 10 can be respectively provided between the pressurized tank body 2 and the bottom plate 1 and the upper cover plate 5. All sealing rings and sealing gaskets are preferably made of fluororubber material, which can improve the pressure resistance of the vacuum pressure impregnation mold. The size and wall thickness of the pressurized tank body 2 should be designed according to the size and pressure parameters of the actual sample.

[0038] In some preferred embodiments, the pressurized tank body 2 is fixedly connected to the base plate 1 and the upper cover plate 5 respectively by countersunk screws, the pressurized plate 3 is fixedly connected to the positioning plate 11 by countersunk screws, and the pressurized plate 3 is fixedly connected to the pressurized rod 4 by countersunk screws.

[0039] In some preferred embodiments, on the pressurized tank body 2, the position of the vacuum port is higher than the position of the slurry port to avoid the slurry being drawn into the vacuum pipeline during the vacuuming process.

[0040] In some preferred embodiments, since the upper cover plate 5 and the threaded sleeve 6 are not in direct contact with the impregnating agent slurry, the materials used can be independently selected from polytetrafluoroethylene or nylon, etc., to seal and reduce the weight of the mold.

[0041] In some preferred embodiments, the materials of the bottom plate 1, the pressurized tank 2, and the pressurized plate 3 are independently selected from 304 or 316 stainless steel to prevent the impregnating agent slurry from chemically reacting with them and affecting the material properties.

[0042] In some preferred embodiments, the pressure rod 4 and the positioning plate 11 are made of quenched 45 steel to reduce deformation caused by pressure.

[0043] The present invention also provides a method for vacuum pressure impregnation using the mold as described above, comprising the following steps:

[0044] The bottom plate 1 is fixedly connected to the pressurized tank body 2, the pressurized plate 3 is fixedly connected to the positioning plate 11, and after placing the sample to be impregnated in the tank body, the pressurized plate 3 is placed inside the pressurized tank body 2, the vacuum port is connected to the vacuum pump through a rubber tube, and the slurry port is connected to a controllable impregnating agent pipeline with a switch;

[0045] The impregnating agent pipeline is controlled to be in a closed state, the vacuum pump is turned on, and the sample to be impregnated is pre-vacuumed, and the gas retained in the pores of the sample to be impregnated is completely pumped out and then the vacuum pump is turned off;

[0046] The impregnating agent pipeline is controlled to be in an open state, so that the impregnating agent enters the tank body under the action of atmospheric pressure, and the impregnating agent pipeline is controlled to be in a closed state after the impregnating agent in the tank body reaches a certain amount; the liquid level of the impregnating agent in the tank body is controlled to be lower than the position of the slurry port;

[0047] Remove the positioning plate 11, and connect the pressure rod 4, the upper cover plate 5 and the threaded sleeve 6 in sequence;

[0048] Turn on the vacuum pump, evacuate the inside of the tank, and then turn off the vacuum pump;

[0049] The mold is placed under a press, the press is in contact with the pressurizing rod 4, the press is turned on, and pressure is applied to the mold to implement a vacuum pressure infusion molding process for the sample.

[0050] After vacuum pressure impregnation molding is completed, demoulding is performed, and one impregnation cycle of the sample is completed.

[0051] Among them, the quantitative pressure impregnation of the sample is achieved by controlling the pressure applied by the press to the mold and then controlling the pressure of the vacuum impregnation inside the tank body; the pressure of the vacuum impregnation inside the tank body is calculated by the indication of the pressure gauge on the press.

[0052] The liquid level of the impregnating agent in the tank is controlled to be lower than the position of the slurry port, mainly to avoid the impregnating agent pipeline being pressurized during the pressurization process and to avoid the risk of bursting due to the pipeline's inability to withstand pressure. The controllable impregnating agent pipeline with a switch can be a metal impregnating agent pipeline with a ball valve, or a simple impregnating agent pipeline made of materials such as PVC hose, which can be opened and closed by a clamp.

[0053] Example 1

[0054] The process of vacuum pressure impregnation of carbon fiber reinforced silicon carbide composite materials using a mold is as follows:

[0055] The bottom plate 1 and the pressurized tank body 2 are connected by countersunk screws, and the contact surface between the bottom plate 1 and the pressurized tank body 2 is sealed by a fluororubber gasket 10, wherein the inner diameter of the pressurized tank body 2 is Φ165mm and the outer diameter is Φ200mm; the bottom plate 1 of the connector is placed downward, and the carbon fiber felt is placed in the pressurized tank body 2, wherein the density of the carbon fiber felt is 0.45g / cm 3 , size Φ150mm*20mm;

[0056] Install the fluorine rubber O-ring 9 on the pressure plate 3, and connect the positioning plate 11 and the pressure plate 3 with countersunk screws; place the pressure plate 3 on the upper part of the pressure tank 2, connect the vacuum port to the vacuum pump through a rubber tube, connect the slurry port to the PVC soft hose, fold the soft hose in half, and seal the pipeline with a clip;

[0057] Turn on the vacuum pump, pre-evacuate the connected mold, and remove the gas retained in the pores of the carbon fiber felt. The vacuum gauge connected to the vacuum pump will display the vacuum degree inside the mold.

[0058] Insert the PVC soft rubber tube into the prepared silicon carbide slurry, turn off the vacuum pump, open the clamp, and slowly loosen the PVC soft rubber tube. The silicon carbide slurry enters the mold under the action of atmospheric pressure; the mold is filled with silicon carbide slurry with a liquid level lower than the slurry port, where the silicon carbide slurry is enough to impregnate the carbon fiber felt, fold the soft rubber tube in half, and seal the pipeline with the clamp;

[0059] Remove the positioning plate 11, and connect the pressurizing rod 4, the upper cover plate 5, and the threaded sleeve 6 in sequence, wherein the contact surface between the upper cover plate 5 and the pressurizing tank body 2 is sealed by a fluororubber gasket 8, and a fluororubber O-ring 7 is installed at the thread of the pressurizing rod 4;

[0060] Turn on the vacuum pump, continue to evacuate the inside of the mold, the vacuum degree is 7KPa, the pressure rod 4 moves downward under the action of atmospheric pressure, and turn off the vacuum pump;

[0061] The mold is placed under a 30T press, the press is in contact with the mold pressure rod 4, the press is turned on, and pressure is applied to the mold. The pressure inside the vacuum pressure impregnation mold is calculated to be 3MPa through the pressure gauge on the press;

[0062] Demolding, completing the impregnation of carbon fiber felt with silicon carbide slurry, and obtaining a carbon fiber reinforced silicon carbide preform, as shown in the figure Figure 3 After drying and degreasing at 1600°C, a carbon fiber reinforced silicon carbide composite material was obtained, and the volume content of silicon carbide in the carbon fiber felt was calculated to be 16.4%.

[0063] The advantages of the present invention using the above technical solution are:

[0064] The vacuum pressure impregnation mold of the present invention comprises a bottom plate, a pressurized tank body, a pressurized plate, a pressurized rod, an upper cover plate, a threaded sleeve, and a positioning plate. The pressurized plate directly pressurizes the liquid surface of the impregnant, and the liquid impregnant is used to transmit pressure so that the impregnant is fully impregnated into the internal pores of the sample to be impregnated. The press applies pressure to the mold through the pressurized rod. The mold is simple, avoiding the use of compressed air or inert gas for pressurization, and reducing the equipment cost. The mold can be designed according to the commonly used size of the sample to avoid the waste of the impregnant. The vacuum pressure impregnation mold of the present invention performs a method for vacuum pressure impregnation. The impregnant can be switched by replacing the impregnant pipeline or using a disposable impregnant pipeline. The mold has wide applicability and is suitable for mass production.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vacuum pressure impregnation mold, characterized in that: It includes a bottom plate, a pressurized tank body, a pressurized plate, a pressurized rod, an upper cover plate, a threaded sleeve and a positioning plate; The bottom plate is fixedly connected to the pressurized tank body and is used to place the sample to be impregnated; the pressurized tank body is provided with a vacuum port and a slurry port, the vacuum port is connected to a vacuum pump through a rubber tube, and the slurry port is connected to a controllable impregnating agent pipeline with a switch; The size of the positioning plate is larger than that of the pressurized tank body. When the sample to be impregnated is pre-vacuumed, the positioning plate is fixed to the pressurized plate and clamps the pressurized plate at the upper end of the pressurized tank body to prevent the pressurized plate from moving downward due to the pressure difference between the inside and outside of the tank body during this process; After the pre-vacuuming of the impregnated sample is completed, the positioning plate is removed, the pressure plate and the pressure rod are fixed, the upper cover plate and the pressurized tank body are fixed, the pressure rod passes through the upper cover plate and is threadedly connected with the threaded sleeve, the threaded sleeve is used to guide the pressure rod, and the interior of the tank body is a closed space after assembly.

2. The vacuum pressure impregnation mold according to claim 1, characterized in that: Sealing rings are respectively arranged at the threads of the pressurizing plate and the pressurizing rod, and sealing gaskets are respectively arranged between the pressurizing tank body and the bottom plate and the upper cover plate.

3. The vacuum pressure impregnation mold according to claim 2, characterized in that: All sealing rings and sealing gaskets are made of fluorine rubber.

4. The vacuum pressure impregnation mold according to claim 1, characterized in that: The pressurized tank body is fixedly connected to the bottom plate and the upper cover plate respectively by countersunk screws, the pressurized plate is fixedly connected to the positioning plate by countersunk screws, and the pressurized plate is fixedly connected to the pressurized rod by countersunk screws.

5. The vacuum pressure impregnation mold according to claim 1, characterized in that: The position of the vacuum port is higher than the position of the slurry port, so as to avoid the slurry being drawn into the vacuum pipeline during the vacuuming process.

6. The vacuum pressure impregnation mold according to claim 1, characterized in that: The materials of the upper cover plate and the threaded sleeve are independently selected from polytetrafluoroethylene or nylon.

7. The vacuum pressure impregnation mold according to claim 1, characterized in that: The materials of the bottom plate, the pressurized tank body, and the pressurized plate are independently selected from 304 or 316 stainless steel.

8. The vacuum pressure impregnation mold according to claim 1, characterized in that: The material of the pressure rod and the positioning plate is 45 steel quenched.

9. A method for vacuum pressure impregnation using the mold according to any one of claims 1 to 8, characterized in that: The following steps are involved: The bottom plate is fixedly connected to the pressurized tank body, the pressurized plate is fixedly connected to the positioning plate, the pressurized plate is placed inside the pressurized tank body after the sample to be impregnated is placed in the tank body, the vacuum port is connected to the vacuum pump through a rubber tube, and the slurry port is connected to a controllable impregnating agent pipeline with a switch; The impregnating agent pipeline is controlled to be in a closed state, the vacuum pump is turned on, and the sample to be impregnated is pre-vacuumed, and the gas retained in the pores of the sample to be impregnated is completely pumped out and then the vacuum pump is turned off; The impregnating agent pipeline is controlled to be in an open state, so that the impregnating agent enters the tank body under the action of atmospheric pressure, and the impregnating agent pipeline is controlled to be in a closed state after the impregnating agent in the tank body reaches a certain amount; the liquid level of the impregnating agent in the tank body is controlled to be lower than the position of the slurry port; Remove the positioning plate, and connect the pressure rod, the upper cover plate and the threaded sleeve in sequence; Turn on the vacuum pump, evacuate the inside of the tank, and then turn off the vacuum pump; The mold is placed under a press, the press is in contact with the pressurizing rod, the press is turned on, and pressure is applied to the mold to achieve a vacuum pressure infusion molding process for the sample.

10. The vacuum pressure impregnation method according to claim 9, characterized in that: The pressure of the vacuum impregnation inside the tank is controlled by controlling the pressure applied by the press to the mold, thereby controlling the pressure of the vacuum impregnation inside the tank, thereby achieving quantitative pressure impregnation of the sample; the pressure of the vacuum impregnation inside the tank is calculated by the indication of the pressure gauge on the press.

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