Forming die and preparation method of SiC / SiC composite C-shaped structural part

Abstract

The present invention relates to a molding die and a method for producing a SiC / SiC composite C-shaped structural component. The molding die comprises a first outer mold, a second outer mold, and a core mold. The first and second outer molds are each C-shaped and mate with each other to form a receiving space, wherein the core mold is located within the receiving space. The first outer mold is provided with a first impregnation channel, and the second outer mold is provided with a second impregnation channel, wherein the first and second impregnation channels are connected. A single molding die can produce two SiC / SiC composite C-shaped structural components, while achieving high processing efficiency and reducing processing costs.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material processing, and in particular to a forming die and a preparation method of a SiC / SiC composite C-shaped structural part. Background Art

[0002] Compared with traditional high-temperature alloys, SiC / SiC composite materials have a density of only 1 / 3 to 1 / 4 of that of high-temperature alloys. They have excellent properties such as high strength, high modulus, and high-temperature oxidation resistance, and are internationally recognized as ideal materials for hot-end components in the aerospace field. C-type structural parts, as a typical web and flange structure, are widely used in aircraft skin reinforcement structures and are one of the important components for improving skin stiffness. C-type structural parts have three surfaces that need to be controlled. In the traditional precursor infusion pyrolysis (PIP) process for preparing SiC / SiC composite C-type structural parts, it is impossible to produce multiple structural parts simultaneously in the same mold like other shaped reinforcement structures such as Ω-shaped, L-shaped, and Z-shaped (CN202010977892). The traditional solution is to use a one-to-one mold preparation (CN202210292078X). This method is inefficient when applied to some C-type structural parts with relatively simple structures. It is easy to cause waste of raw materials during the process, which is not conducive to cost control and limits the development of its engineering application.

[0003] Therefore, the present invention provides a forming die and a preparation method for a SiC / SiC composite C-shaped structural member. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] The embodiments of the present invention provide a forming die and a preparation method for a SiC / SiC composite C-shaped structural member, which solve the technical problems of low processing efficiency and high cost.

[0006] (2) Technical solution

[0007] In order to solve the above technical problems, the present invention provides a first aspect of a molding die for a SiC / SiC composite C-shaped structural member, comprising a first outer mold, a second outer mold and a core mold;

[0008] The first outer mold and the second outer mold are respectively C-shaped, and the first outer mold and the second outer mold are aligned with each other to form an accommodating space, and the core mold is located in the accommodating space;

[0009] The first outer mold is provided with a first impregnation channel, the second outer mold is provided with a second impregnation channel, and the first impregnation channel and the second impregnation channel are communicated.

[0010] Optionally, a first positioning pin hole is provided on the first outer mold, a second positioning pin hole is provided on the second outer mold, and a positioning pin is connected between the first positioning pin hole and the second positioning pin hole; a first connecting hole is provided on the first outer mold, a second connecting hole is provided on the second outer mold, and a connecting piece is connected between the first connecting hole and the second connecting hole.

[0011] In a second aspect, the present invention provides a method for preparing a SiC / SiC composite C-shaped structural member, comprising:

[0012] Placing two fiber preforms in a mold for a SiC / SiC composite C-shaped structural member, with one side of the two fiber preforms attached to the core mold and the other sides of the two fiber preforms correspondingly attached to the first outer mold and the second outer mold, respectively;

[0013] placing the molding die with the fiber preform into a vacuum container, and then placing the molding die and the fiber preform into an autoclave for pressure molding;

[0014] forming an interface layer on the surface of the fiber preform;

[0015] Performing a preliminary densification treatment on the fiber preform to obtain a porous C-shaped structural member blank;

[0016] Further densifying the C-shaped structural part blank to obtain a dense C-shaped structural part blank;

[0017] The dense C-shaped structural part blank is processed into a C-shaped structural part.

[0018] Optionally, the interface layer is a pyrolytic carbon interface layer or a boron nitride interface layer.

[0019] Optionally, the fiber preform is 2D, 2.5D or 3D.

[0020] Optionally, the preliminary densification treatment of the fiber preform to obtain a porous C-shaped structural member blank comprises:

[0021] The fiber preform is subjected to a preliminary densification treatment using a ceramic precursor solution to obtain a porous C-shaped structural component blank.

[0022] Optionally, the ceramic precursor solution is a polycarbosilane solution or liquid polycarbosilane.

[0023] Optionally, the solute of the polycarbosilane solution is polycarbosilane, and the solvent of the polycarbosilane solution is xylene.

[0024] (3) Beneficial effects

[0025] In summary, in the molding die and preparation method of the SiC / SiC composite material C-type structural part of the present invention, when preparing the SiC / SiC composite material C-type structural part, two fiber preforms are placed on a core mold, vacuum isostatic pressing is used to assist molding to obtain two C-type fiber preforms, propane and argon are used as gas sources to prepare a PyC interface layer, polycarbosilane is used as a precursor, and xylene is used as a solvent to prepare a SiC ceramic matrix, and after densification, two SiC / SiC composite material C-type structural parts are obtained by mechanical processing. When the molding die of the SiC / SiC composite material C-type structural part of the present embodiment is used to prepare the SiC / SiC composite material C-type structural part, the core mold can control the inner surface of the first outer mold and the second outer mold, and the length dimension of the core mold cross section is equal to the sum of the dimensions of the first outer mold and the second outer mold after relative placement plus the dimension of the machining allowance. Two SiC / SiC composite material C-type structural parts can be prepared at one time. At the same time, the processing efficiency is high and the processing cost can be saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. 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 any creative work.

[0027] Figure 1 1 is a schematic structural diagram of a molding die for a SiC / SiC composite C-shaped structural member according to an embodiment of the present invention;

[0028] Figure 2 1 is another structural schematic diagram of a forming die for a SiC / SiC composite C-shaped structural member according to one embodiment of the present invention;

[0029] Figure 3 This is a diagram showing the connection relationship between the core mold and two position-limiting preforms in one embodiment of the present invention;

[0030] Figure 4 It is a structural schematic diagram of a C-shaped structural part forming die in the prior art.

[0031] In the figure: 1-core mold; 2-first outer mold; 3-second outer mold; 4-first impregnation channel; 5-first positioning pin hole; 6-first connecting hole; 7-fiber preform. DETAILED DESCRIPTION

[0032] The following detailed description of the embodiments of the present invention is provided in conjunction with the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are intended to illustrate the principles of the present invention and are not intended to limit the scope of the present invention. That is, the present invention is not limited to the described embodiments and covers any modifications, replacements, and improvements to the parts, components, and connection methods without departing from the spirit of the present invention.

[0033] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0034] It should be noted that the various embodiments in this specification are described in a progressive manner. References to the same or similar parts between the various embodiments are sufficient. Each embodiment focuses on the differences from the other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and technologies are omitted here.

[0035] Please refer to Figures 1 to 4 A forming mold for a SiC / SiC composite C-shaped structural part includes a first outer mold, a second outer mold and a core mold; the first outer mold and the second outer mold are respectively C-shaped, the first outer mold and the second outer mold are matched with each other to form an accommodating space, and the core mold is located in the accommodating space; a first impregnation channel is provided on the first outer mold, and a second impregnation channel is provided on the second outer mold (not shown in the figure), and the first impregnation channel and the second impregnation channel are connected.

[0036] When preparing a SiC / SiC composite C-type structural part, two fiber preforms are placed on a core mold and vacuum isostatic pressing is used to assist molding to obtain two C-type fiber preforms. A PyC interface layer is prepared using propane and argon as gas sources, polycarbosilane is used as a precursor, and xylene is used as a solvent to prepare a SiC ceramic matrix. After densification, two SiC / SiC composite C-type structural parts are obtained by mechanical processing. When using the molding mold of the SiC / SiC composite C-type structural part of this embodiment to prepare the SiC / SiC composite C-type structural part, the core mold can control the inner surface of the first outer mold and the second outer mold. The length dimension of the core mold cross section is equal to the sum of the dimensions of the first outer mold and the second outer mold after relative placement plus the dimension of the machining allowance. Two SiC / SiC composite C-type structural parts can be prepared at one time. At the same time, the processing efficiency is high and the processing cost can be saved. Among them, the SiC matrix precursor is injected through the first impregnation flow channel and the second impregnation flow channel.

[0037] In one embodiment, the first outer mold is provided with a first positioning pin hole, the second outer mold is provided with a second positioning pin hole (not shown in the figure), and a positioning pin is connected between the first positioning pin hole and the second positioning pin hole; the first outer mold is provided with a first connecting hole, the second outer mold is provided with a second connecting hole (not shown in the figure), and a connecting piece is connected between the first connecting hole and the second connecting hole. The mutual cooperation of the first positioning pin hole, the second positioning pin hole and the positioning pin can position the second outer mold and the first outer mold, and facilitate the connection of the second outer mold and the first outer mold. The connection of the first connecting hole, the second connecting hole and the connecting piece can connect and fix the second outer mold to the first outer mold. Specifically, the first connecting hole and the second connecting hole are threaded holes, and the connecting piece is a screw, which is easy to disassemble and assemble and has a simple structure.

[0038] This embodiment also provides a method for preparing a SiC / SiC composite C-shaped structural member, comprising:

[0039] Placing two fiber preforms in a mold for a SiC / SiC composite C-shaped structural member, with one side of the two fiber preforms attached to the core mold and the other sides of the two fiber preforms correspondingly attached to the first outer mold and the second outer mold, respectively;

[0040] placing the molding die with the fiber preform into a vacuum container, and then placing the molding die and the fiber preform into an autoclave for pressure molding;

[0041] forming an interface layer on the surface of the fiber preform;

[0042] Performing a preliminary densification treatment on the fiber preform to obtain a porous C-shaped structural member blank;

[0043] Further densifying the C-shaped structural part blank to obtain a dense C-shaped structural part blank;

[0044] The dense C-shaped structural part blank is processed into a C-shaped structural part.

[0045] In the preparation method of the SiC / SiC composite material C-type structural member of this embodiment,

[0046] In one embodiment, forming an interface layer on the surface of the fiber preform includes: placing the fiber preform into the forming mold, placing the preform into a PyC chemical vapor deposition furnace, evacuating the furnace to a vacuum of 50 Pa, then heating the furnace to 300°C, holding the temperature for 1 hour, then further heating the temperature to 1000°C, holding the temperature for 1 hour, introducing argon and propane at a flow rate ratio of 1:1, and depositing at a pressure of 2000 Pa. After 15 hours of deposition, the temperature is lowered to room temperature, and the PyC interface layer has a thickness of 200 nm. The interface layer is a pyrolytic carbon interface layer or a boron nitride interface layer.

[0047] In one embodiment, the fiber preform is 2D, 2.5D, or 3D, wherein 2D represents a two-dimensional structure, 2.5D represents a 2.5-dimensional structure, and 3D represents a three-dimensional structure.

[0048] In one embodiment, the preliminary densification treatment of the fiber preform to obtain a porous C-shaped structural component blank includes: preliminary densification treatment of the fiber preform using a ceramic precursor solution to obtain a porous C-shaped structural component blank. Specifically, a polycarbosilane precursor is used as a solute, xylene is used as a solvent, and polycarbosilane accounts for 50% by weight of the precursor impregnation solution. The solution is uniformly stirred at room temperature for 24 hours to obtain a SiC ceramic precursor solution. A fiber preform with a forming mold and an interface layer prepared thereon is placed in a vacuum impregnation device, and the vacuum impregnation device is evacuated with a vacuum pump. When the pressure in the inner cavity of the vacuum impregnation device is less than 100 Pa, the SiC ceramic precursor solution is introduced into the inner cavity of the vacuum impregnation device through a stainless steel pipe, and finally the fiber preform with the forming mold is completely submerged in the ceramic precursor solution, and the impregnation treatment is carried out for 24 hours. The fiber preform with the forming mold is then placed in a high-temperature cracking furnace, evacuated to 50 Pa, heated to 1200°C at a heating rate of 10°C / min, and kept warm for 1 hour. After the impregnation-cracking cycle is repeated 6 times, a porous C-shaped structural part blank is obtained after demolding.

[0049] The C-type structural part blank is subjected to further densification treatment to obtain a dense C-type structural part blank, comprising: placing the C-type structural part blank in a vacuum impregnation device, evacuating the vacuum impregnation device with a vacuum pump, introducing a ceramic precursor solution into the inner cavity of the vacuum impregnation device through a stainless steel pipeline when the pressure in the inner cavity of the vacuum impregnation device is less than 100 Pa, and finally submerging the porous C-type structural part blank in the ceramic precursor solution and maintaining it for 12 hours, then placing it again in a forming mold and placing it in a high-temperature cracking furnace to evacuate to 50 Pa, heating it to 1200° C. at a heating rate of 10° C. / min, keeping it warm for 1 hour, demolding and weighing, repeating the impregnation-molding-high-temperature cracking-demolding process, and completing the matrix densification process of the C-type structural part blank when the weight of the C-type structural part blank after impregnation and cracking is less than 1% of the weight gain rate before impregnation to obtain a dense C-type structural part blank.

[0050] In one embodiment, the ceramic precursor solution is a polycarbosilane solution or liquid polycarbosilane.

[0051] In one embodiment, the solute of the polycarbosilane solution is polycarbosilane, and the solvent of the polycarbosilane solution is xylene.

[0052] Processing the dense C-shaped structural part blank into a C-shaped structural part includes: processing the dense C-shaped structural part blank according to the drawing requirements to obtain a C-shaped structural part with a net size, polishing it with 1200-mesh water sandpaper, and then cleaning the polished area with anhydrous ethanol and drying it to complete the preparation of the C-shaped structural part.

[0053] Design the original solution mold based on the same boundary constraints, please refer to Figure 4 , Figure 4 This is a schematic diagram of the structure of the C-shaped structural part forming mold in the prior art. After measurement and calculation, the volume of the forming mold in this embodiment is 1824.8cm 3 , a set of forming molds can simultaneously produce two C-shaped structural parts. The volume of the forming mold in the prior art is 1469.5cm 3 , a set of molds can only produce one C-shaped structural part. Therefore, compared with the prior art, the molding mold and preparation method of the SiC / SiC composite C-shaped structural part of this embodiment improves production efficiency while reducing the mold volume by approximately 40% compared to the prior art, saving costs and reducing the waste of precursor solution during the process.

[0054] The above are merely embodiments of the present application and are not intended to limit the present application. Various modifications and variations are possible for those skilled in the art without departing from the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for preparing a SiC / SiC composite C-shaped structural member, characterized in that: The forming die of the SiC / SiC composite C-shaped structural part comprises a first outer die, a second outer die and a core die; The first outer mold and the second outer mold are respectively C-shaped, and the first outer mold and the second outer mold are aligned with each other to form an accommodating space. The core mold is located in the accommodating space. The length of the cross section of the core mold is equal to the sum of the dimensions of the first outer mold and the second outer mold after being placed relative to each other plus the dimension of the machining allowance; The first outer mold is provided with a first impregnation flow channel, the second outer mold is provided with a second impregnation flow channel, the first impregnation flow channel and the second impregnation flow channel are connected; The preparation method comprises the following steps: Placing two fiber preforms in a mold for a SiC / SiC composite C-shaped structural member, with one side of the two fiber preforms attached to the core mold and the other sides of the two fiber preforms correspondingly attached to the first outer mold and the second outer mold, respectively; placing the molding die with the fiber preform into a vacuum container, and then placing the molding die and the fiber preform into an autoclave for pressure molding; forming an interface layer on the surface of the fiber preform; Performing a preliminary densification treatment on the fiber preform to obtain a porous C-shaped structural member blank; Further densifying the C-shaped structural part blank to obtain a dense C-shaped structural part blank; The dense C-shaped structural part blank is processed into a C-shaped structural part.

2. The preparation method according to claim 1, characterized in that The first outer mold is provided with a first positioning pin hole, the second outer mold is provided with a second positioning pin hole, and a positioning pin is connected between the first positioning pin hole and the second positioning pin hole; the first outer mold is provided with a first connecting hole, the second outer mold is provided with a second connecting hole, and a connecting piece is connected between the first connecting hole and the second connecting hole.

3. The preparation method according to claim 1, characterized in that The interface layer is a pyrolytic carbon interface layer or a boron nitride interface layer.

4. The preparation method according to claim 1, characterized in that The fiber preform is 2D, 2.5D or 3D.

5. The preparation method according to any one of claims 1 to 4, characterized in that The preliminary densification treatment of the fiber preform to obtain a porous C-shaped structural member blank comprises: The fiber preform is subjected to a preliminary densification treatment using a ceramic precursor solution to obtain a porous C-shaped structural component blank.

6. The preparation method according to claim 5, characterized in that The ceramic precursor solution is a polycarbosilane solution or liquid polycarbosilane.

7. The preparation method according to claim 6, characterized in that The solute of the polycarbosilane solution is polycarbosilane, and the solvent of the polycarbosilane solution is xylene.

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