Integral forming die and preparation method of SiC / SiC composite material reinforced wall panel

Abstract

The present invention relates to an integral forming mold and preparation method for SiC / SiC composite material reinforced wall panels. The integral forming mold for the SiC / SiC composite material reinforced wall panels comprises a bottom mold, a top mold and a core mold; the bottom mold is provided with a first impregnation channel, the top mold is provided with a second impregnation channel, the first impregnation channel and the second impregnation channel are connected, and the core mold is located between the top mold and the bottom mold. Compared with the split preparation method of the densification process in the prior art, the connection strength between the wall panel preform and the reinforcement preform of the present invention is high. Compared with the integral weaving method in the prior art, the opening structure in the present invention does not require processing, thereby saving materials and costs.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material processing, and in particular to an integral forming die and a preparation method for a SiC / SiC composite material reinforced wallboard. Background Art

[0002] Compared to traditional high-temperature alloys, SiC / SiC composites have a density only one-third to one-quarter that of high-temperature alloys. They offer excellent properties such as high strength, high modulus, and high-temperature oxidation resistance, making them internationally recognized as ideal materials for hot-end components in the aerospace industry. A stiffened panel structure is a composite structure composed of a main structure (skin) and stiffeners (such as stringers, ribs, longitudinals, and beams) connected in a specific manner. To meet diverse needs, a variety of stiffened panel structures are used in engineering practice. Omega-shaped stiffeners are gaining increasing attention among structural design engineers due to their high compressive stability. Omega-shaped stiffeners typically have a large cross-section, with their two sides connected to the skin to form a closed cross-section. They exhibit high post-buckling resistance under compressive loads and are commonly used in primary load-bearing structures subjected to severe loading conditions. Furthermore, omega-shaped stiffeners enhance the torsional stability and buckling strength of components, allowing for a wider skin width between two stiffeners in the panel design, which helps reduce the number of parts. There are usually two methods to manufacture SiC / SiC composite Ω-shaped reinforced wall panels: one is to prepare Ω-shaped reinforcement ribs and wall panels separately through a densification process, and then assemble them into integral Ω-shaped reinforced wall panels through online connection, mechanical connection, welding, gluing and other methods; the other is to adopt an integral weaving method to weave solid reinforcement ribs as a whole onto the wall panel preform, and obtain Ω-shaped reinforced wall panels through fine processing.

[0003] The densification process, a split-piece fabrication method, is limited by the connection method and requires opening holes in the composite material, which can damage the composite's structural integrity or cause thermal expansion mismatches in the connecting layers, resulting in lower structural strength. The monolithic braiding method, however, cannot weave open-end reinforcement preforms, requiring the braiding of solid reinforcement preforms, which are then processed to produce Ω-shaped reinforcements. This increases the costs of fiber, preform braiding, matrix materials, and processing, hindering the widespread application of Ω-shaped stiffened panels in the aviation industry. A low-cost monolithic manufacturing method for SiC / SiC composite Ω-shaped stiffened panels is urgently needed.

[0004] Therefore, the present invention provides an integral forming die and a preparation method for a SiC / SiC composite material reinforced wall panel. Summary of the Invention

[0005] (1) Technical problems to be solved

[0006] The embodiment of the present invention provides an integral forming die and a preparation method for a SiC / SiC composite material reinforced wall panel, which solves the technical problems of low connection strength and high cost.

[0007] (2) Technical solution

[0008] In order to solve the above technical problems, in a first aspect, the present invention proposes an integral forming die for a SiC / SiC composite reinforced wall panel, comprising a bottom die, a top die and a core die;

[0009] The bottom mold is provided with a first impregnation flow channel, the top mold is provided with a second impregnation flow channel, the first impregnation flow channel and the second impregnation flow channel are communicated, and the core mold is located between the top mold and the bottom mold.

[0010] Optionally, the bottom mold has a receiving groove frame in the middle, the edge of the receiving groove frame is provided with a positioning groove, the top mold is clamped in the receiving groove frame, and the core mold is located in the positioning groove.

[0011] Optionally, a first positioning pin hole is provided on the bottom mold, a second positioning pin hole is provided on the top 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 bottom mold, a second connecting hole is provided on the top mold, and a connecting piece is connected between the first connecting hole and the second connecting hole.

[0012] In a second aspect, the present invention further provides a method for preparing a reinforced wall panel, comprising:

[0013] Installing the mold, obtaining a wall panel preform and a rib preform, and installing the wall panel preform and the rib preform in an integral forming mold of a SiC / SiC composite material reinforced wall panel;

[0014] Stitching, stitching the wall panel preform and the reinforcement preform to obtain a reinforced wall panel preform;

[0015] Preparation of an interface layer, forming an interface layer on the surface of the reinforced wall panel prefabricated body;

[0016] Preliminary densification: obtaining a ceramic precursor solution, impregnating the reinforced wall panel preform in the ceramic precursor solution, then heating the impregnated reinforced wall panel preform to a precursor ceramic transition point temperature for high-temperature cracking, and separating the reinforced wall panel preform from the integral forming mold to obtain a porous reinforced wall panel blank;

[0017] Further densification is performed by immersing the stiffened wall panel blank in a ceramic precursor solution for vacuum impregnation treatment, and then re-loading the stiffened wall panel blank into the integral forming mold for further high-temperature cracking, and demolding the stiffened wall panel blank from the integral forming mold;

[0018] Repeat the steps to further densify, and when the weight increase rate of the reinforced wall panel blank after impregnation and cracking is less than 1% of the reinforced wall panel blank before impregnation and cracking, a dense reinforced wall panel blank is obtained;

[0019] Machining is to process the dense reinforced wall panel blank into a target workpiece of the reinforced wall panel.

[0020] Optionally, the molding comprises:

[0021] The wall panel preform is attached to the bottom mold, the rib preform is attached to the core mold, the core mold is installed between the top mold and the bottom mold, and then the wall panel preform, the rib preform, the top mold, the bottom mold and the core mold are cured using spray adhesive.

[0022] Optionally, the interface layer is a pyrolytic carbon interface layer or a boron nitride interface layer.

[0023] Optionally, the ceramic precursor solution is a polycarbosilane solution or liquid polycarbosilane.

[0024] Optionally, during the precursor impregnation and high-temperature pyrolysis, the reinforced wall panel preform is immersed in the ceramic precursor solution for 24 hours to 48 hours, and the high-temperature pyrolysis time is 0.5 hours to 2 hours.

[0025] Optionally, in the further densification step, the reinforced wall panel green body is immersed in a ceramic precursor solution for 12 hours to 24 hours.

[0026] Optionally, the suturing comprises:

[0027] The wall panel preform and the reinforcement preform are sewn together by using continuous SiC fiber or core-wrapped SiC fiber to obtain a reinforced wall panel preform.

[0028] (3) Beneficial effects

[0029] In summary, in the integral forming mold and preparation method of the SiC / SiC composite material reinforced wall panel of the present invention, before processing the reinforced wall panel, a wall panel preform and a rib preform can be prepared first. The wall panel preform and the rib preform are respectively formed by weaving, and the wall panel preform and the rib preform respectively have many porous structures. When processing the reinforced wall panel, the wall panel preform is installed on the bottom mold, the rib preform is installed on the core mold, and then the core mold is placed on the bottom mold, and finally the top mold is covered on the core mold and the bottom mold. An open structure is formed between the wall panel preform and the rib preform. The SiC composite material is impregnated into the wall panel preform and the rib preform through the first impregnation flow channel and the second impregnation flow channel, and finally the target workpiece of the reinforced wall panel is processed by machining. The target workpiece of the reinforced wall panel thus obtained also has an open structure. Compared with the split preparation method of the densification process in the prior art, the connection strength of the wall panel preform and the rib preform of the present invention is high. Compared with the overall weaving method in the prior art, the open structure in the present invention does not require processing, thus saving materials and costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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.

[0031] Figure 1 2 is a schematic structural diagram of an integral forming die for a SiC / SiC composite material reinforced wall panel according to an embodiment of the present invention;

[0032] Figure 2 This is a schematic structural diagram of a bottom mold in one embodiment of the present invention;

[0033] Figure 3 2 is a schematic structural diagram of a core mold in one embodiment of the present invention;

[0034] Figure 4 This is a schematic structural diagram of a wall panel prefabricated body according to one embodiment of the present invention;

[0035] Figure 5 This is a schematic structural diagram of a reinforcement prefabricated body according to an embodiment of the present invention;

[0036] Figure 6 Schematic diagram of the stitching of a wall panel preform and a rib preform in one embodiment of the present invention.

[0037] In the figure: 1-bottom mold; 2-core mold; 3-top mold; 4-second impregnation channel; 5-second positioning pin hole; 6-second connecting hole; 7-positioning groove; 8-positioning boss; 9-wall panel preform; 10-rib preform; 11-core-wrapped SiC fiber. DETAILED DESCRIPTION

[0038] 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.

[0039] 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.

[0040] 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.

[0041] Please refer to Figures 1 to 6 In the first aspect, this embodiment proposes an integral forming mold for a SiC / SiC composite reinforced wall panel, comprising a bottom mold 1, a top mold 3, and a core mold 2; the bottom mold 1 is provided with a first impregnation channel, the top mold 3 is provided with a second impregnation channel 4, the first impregnation channel and the second impregnation channel 4 are connected, and the core mold 2 is located between the top mold 3 and the bottom mold 1. Before processing the reinforced wall panel, a wall panel preform 9 and a rib preform 10 can be prepared first. The wall panel preform 9 and the rib preform 10 are respectively formed by weaving, and the wall panel preform 9 and the rib preform 10 each have a plurality of porous structures. When processing the reinforced wall panel, the wall panel preform 9 is installed on the bottom mold 1, the rib preform 10 is installed on the core mold 2, and then the core mold 2 is placed on the bottom mold 1, and finally the top mold 3 is covered on the core mold 2 and the bottom mold 1. An opening structure is formed between the wall panel preform 9 and the rib preform 10. The SiC composite material and the like are impregnated into the wall panel preform 9 and the rib preform 10 through the first impregnation flow channel and the second impregnation flow channel 4, and finally processed into the target workpiece of the reinforced wall panel through machining. The target workpiece of the reinforced wall panel thus obtained also has an open structure. Compared with the split preparation method of the densification process in the prior art, the connection strength between the wall panel preform 9 and the rib preform 10 in this embodiment is high. Compared with the integral weaving method in the prior art, the open structure in this embodiment does not need to be processed, so it can save materials and costs. Among them, the SiC matrix precursor is injected through the first impregnation flow channel and the second impregnation flow channel. 。

[0042] In one embodiment, the bottom mold 1 has a receiving groove frame in the middle, and the edges of the receiving groove frame are provided with positioning grooves 7. The top mold 3 is clamped in the receiving groove frame, and the core mold 2 is provided with positioning bosses 8. The core mold 2 is installed in the positioning groove 7 via the positioning bosses 8. The receiving groove frame is located in the middle of the top surface of the bottom mold 1. The receiving groove frame is square and can clamp the top mold 3 therein. The receiving groove frame has a support function for the top mold 3. Positioning grooves 7 are respectively provided at both ends of the receiving groove frame. The ends of the core mold 2 are clamped in the positioning grooves 7. The positioning grooves 7 have a support and fixation function for the core mold 2.

[0043] In one embodiment, the bottom mold 1 is provided with a first positioning pin hole, the top mold 3 is provided with a second positioning pin hole 5, and a positioning pin is connected between the first positioning pin hole and the second positioning pin hole 5; the bottom mold 1 is provided with a first connecting hole, the top mold 3 is provided with a second connecting hole 6, and a connecting piece is connected between the first connecting hole and the second connecting hole 6. The mutual cooperation between the first positioning pin hole, the second positioning pin hole 5 and the positioning pin can position the top mold 3 and the bottom mold 1, and facilitate the connection between the top mold 3 and the bottom mold 1. The connection between the first connecting hole, the second connecting hole 6 and the connecting piece can connect and fix the top mold 3 and the bottom mold 1. Specifically, the first connecting hole and the second connecting hole 6 are threaded holes, and the connecting piece is a screw, which is easy to disassemble and assemble and has a simple structure.

[0044] In a second aspect, this embodiment further provides a method for preparing a reinforced wall panel, comprising:

[0045] Installing the mold, obtaining the wall panel preform 9 and the rib preform 10, and installing the wall panel preform 9 and the rib preform 10 in the integral forming mold of the SiC / SiC composite material reinforced wall panel;

[0046] Stitching, stitching the wall panel preform 9 and the reinforcement preform 10 to obtain a reinforced wall panel preform 9;

[0047] Preparation of an interface layer, forming an interface layer on the surface of the reinforced wall panel preform 9;

[0048] Preliminary densification: obtaining a ceramic precursor solution, impregnating the reinforced wall panel preform 9 in the ceramic precursor solution, then heating the impregnated reinforced wall panel preform 9 to the precursor ceramic transition point temperature for high-temperature cracking, repeating the impregnation and high-temperature cracking cycles several times, and then separating the reinforced wall panel preform 9 from the integral forming mold to obtain a porous reinforced wall panel blank;

[0049] Further densification is performed by immersing the stiffened wall panel blank 9 in a ceramic precursor solution for vacuum impregnation treatment, and then re-loading it into the integral forming mold for further high-temperature cracking, and demolding the stiffened wall panel blank and the integral forming mold;

[0050] Repeat the above steps to further densify the wall panel blank until the weight gain rate of the reinforced wall panel blank 9 after impregnation and cracking is less than 1% of the reinforced wall panel blank before impregnation and cracking, and obtain a dense reinforced wall panel blank;

[0051] Machining is to process the dense reinforced wall panel blank into a target workpiece of the reinforced wall panel.

[0052] In the method for preparing reinforced wall panels of this embodiment, an open structure is formed between the wall panel preform 9 and the rib preform 10, so the resulting reinforced wall panel also has an open structure. Compared to the existing split-densification process preparation method, the connection strength between the wall panel preform 9 and the rib preform 10 of this embodiment is higher. Compared to the existing integral braiding method, the open structure of this embodiment does not require processing, thus saving materials and costs.

[0053] In one embodiment, the mold assembly includes attaching the wall panel preform 9 to the bottom mold 1, attaching the rib preform 10 to the core mold 2, installing the core mold 2 between the top mold 3 and the bottom mold 1, and then using a spray adhesive to solidify the wall panel preform 9, the rib preform 10, the top mold 3, the bottom mold 1, and the core mold 2. The mold is tightened and pressed for 4 hours using locking bolts. The use of a spray adhesive has the advantages of convenient operation, fast room temperature curing speed, a tight fit between the fiber preform and the mold surface, and no impurities introduced.

[0054] In one embodiment, the stitching includes: after removing the top mold 3, using continuous SiC fiber or core-wrapped SiC fiber 11 to stitch the wall panel preform 9 and the reinforcement preform 10 to obtain a reinforced wall panel preform 9.

[0055] In one embodiment, the interface layer is a pyrolytic carbon interface layer or a boron nitride interface layer. The interface layer preparation step includes placing the reinforced wall panel preform 9 with a mold 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 and holding the temperature for 1 hour. Argon and propane are introduced at a flow rate ratio of 1:1, the deposition pressure is 2000 Pa, and after 15 hours of deposition, the temperature is cooled to room temperature. The resulting PyC interface layer has a thickness of 200 nm.

[0056] In one embodiment, the ceramic precursor solution is a polycarbosilane solution or liquid polycarbosilane.

[0057] In one embodiment, during the preliminary densification, the reinforced wall panel preform 9 is immersed in the ceramic precursor solution for 24 hours to 48 hours, and the high temperature pyrolysis time is 0.5 hours to 2 hours. Specifically, the precursor impregnation and pyrolysis process includes: using a polycarbosilane precursor as the solute and xylene as the solvent, with the polycarbosilane accounting for 50% by weight of the precursor impregnation solution; uniformly stirring at room temperature for 24 hours to obtain a SiC ceramic precursor solution; placing the reinforced wall panel preform 9 with the mold in a vacuum impregnation apparatus; evacuating the vacuum impregnation apparatus with a vacuum pump; and introducing the SiC ceramic precursor solution into the vacuum impregnation apparatus through a stainless steel pipe when the pressure in the vacuum impregnation apparatus is less than 100 Pa. Ultimately, the reinforced wall panel preform 9 with the mold is completely submerged in the ceramic precursor solution, and the impregnation process continues for 24 hours; then, placing the reinforced wall panel preform 9 with the mold in a pyrolysis furnace, evacuating the pressure to 50 Pa, heating to 1200°C at a heating rate of 10°C / min, and maintaining the temperature for 1 hour. After repeating the precursor impregnation and pyrolysis steps four times, the process proceeds to the preliminary densification step.

[0058] In one embodiment, in the further densification step, the stiffened wall panel green body is immersed in a ceramic precursor solution for 12 hours to 24 hours. Specifically, the second densification includes: placing the reinforced wall panel preform 9 with a mold in a vacuum impregnation device, vacuuming the vacuum impregnation device with a vacuum pump, and when the pressure in the inner cavity of the vacuum impregnation device is less than 100Pa, introducing the ceramic precursor solution into the inner cavity of the vacuum impregnation device through a stainless steel pipe. Finally, the reinforced wall panel preform 9 with the mold is submerged in the ceramic precursor solution and maintained for 12 hours. Then, it is placed in the mold again and placed in a high-temperature cracking furnace and vacuumed to 50Pa. It is heated to 1200℃ at a heating rate of 10℃ / min, kept warm for 1 hour, demolded and weighed, and the impregnation-molding-high-temperature cracking-demolding process is repeated. When the weight of the reinforced wall panel preform 9 after impregnation and cracking is less than 1% of the weight gain rate before impregnation, the matrix densification process of the reinforced wall panel preform 9 is completed to obtain a densified reinforced wall panel blank.

[0059] In one embodiment, the machining includes: processing the dense reinforced wall panel blank according to the requirements of the drawing to obtain the target workpiece of the reinforced wall panel 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 reinforced wall panel.

[0060] 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 reinforced wall panel, characterized in that: The integral forming mold of the SiC / SiC composite reinforced wall panel includes a bottom mold, a top mold and a core mold; The bottom mold is provided with a first impregnation flow channel, the top mold is provided with a second impregnation flow channel, the first impregnation flow channel and the second impregnation flow channel are connected, and the core mold is located between the top mold and the bottom mold; The bottom mold has a receiving groove frame in the middle, and a positioning groove is provided on the edge of the receiving groove frame. The top mold is clamped in the receiving groove frame, and positioning bosses are provided at both ends of the core mold. The core mold is installed in the positioning groove through the positioning bosses. The preparation method comprises the following steps: setting a mold, obtaining a wall panel preform and a rib preform, installing the wall panel preform and the rib preform in an integral forming mold of a SiC / SiC composite reinforced wall panel, laminating the wall panel preform on a bottom mold, laminating the rib preform on a core mold, installing the core mold between a top mold and a bottom mold, and then curing the wall panel preform, the rib preform, the top mold, the bottom mold and the core mold by spraying adhesive; Stitching, stitching the wall panel preform and the reinforcement preform to obtain a reinforced wall panel preform; Preparation of an interface layer, forming an interface layer on the surface of the reinforced wall panel prefabricated body; Preliminary densification: obtaining a ceramic precursor solution, impregnating the reinforced wall panel preform in the ceramic precursor solution, then heating the impregnated reinforced wall panel preform to a precursor ceramic transition point temperature for high-temperature cracking, and separating the reinforced wall panel preform from the integral forming mold to obtain a porous reinforced wall panel blank; Further densification is performed by immersing the stiffened wall panel blank in a ceramic precursor solution for vacuum impregnation treatment, and then re-loading the stiffened wall panel blank into the integral forming mold for further high-temperature cracking, and demolding the stiffened wall panel blank from the integral forming mold; Repeat the steps to further densify, and when the weight increase rate of the reinforced wall panel blank after impregnation and cracking is less than 1% of the reinforced wall panel blank before impregnation and cracking, a dense reinforced wall panel blank is obtained; Machining is to process the dense reinforced wall panel blank into a target workpiece of the reinforced wall panel.

2. The method for preparing the reinforced wall panel according to claim 1, characterized in that: The bottom mold is provided with a first positioning pin hole, the top 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 bottom mold is provided with a first connecting hole, the top 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 ceramic precursor solution is a polycarbosilane solution or liquid polycarbosilane.

5. The preparation method according to claim 1, characterized in that During the precursor impregnation and high-temperature pyrolysis, the reinforced wall panel preform is immersed in the ceramic precursor solution for 24 hours to 48 hours, and the high-temperature pyrolysis time is 0.5 hours to 2 hours.

6. The preparation method according to claim 1, characterized in that In the further densification step, the reinforced wall panel green body is immersed in a ceramic precursor solution for 12 hours to 24 hours.

7. The preparation method according to claim 1, characterized in that The suturing comprises: The wall panel preform and the reinforcement preform are sewn together by using continuous SiC fiber or core-wrapped SiC fiber to obtain a reinforced wall panel preform.

Images