Near-net forming die and forming method for ceramic-based composite flat plate part
By combining a split mold design with graphite fixtures, the deformation problem of ceramic matrix composite parts during chemical vapor infiltration was solved, achieving precise control of part shape and shortening the production cycle, thus reducing costs.
Patent Information
- Application Number
- CN202511069245.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-31
- Publication Date
- 2025-10-17
AI Technical Summary
Ceramic matrix composite parts are prone to deformation during chemical vapor infiltration, which affects the dimensional accuracy of the parts and the production cycle, leading to increased production costs.
The upper and lower mold components adopt a split design and are combined with graphite fixtures. During chemical vapor deposition, the preform and the mold components are processed together. In the later stage, only the upper and lower molds are removed, while the upper and lower frames are retained to avoid high-temperature deformation.
This effectively prevents the prefabricated body from deforming at high temperatures, ensures the standard shape of the parts, shortens the production cycle, and reduces costs.
Smart Images
Figure CN120791945A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of ceramic matrix composite forming processing, and particularly relates to a near-net forming die and a forming method for ceramic matrix composite flat plate parts. BACKGROUND
[0002] As a new type of thermal structure / function integrated strategic material, ceramic matrix composite has the characteristics of low density, high temperature resistance, high specific strength, high specific modulus, oxidation resistance, ablation resistance, crack insensitivity and non-disastrous damage, and is widely used in key fields such as aviation, aerospace, nuclear power and photovoltaic. Ceramic matrix composite products are usually assembled by parts with different structures and sizes. Deformation control during preparation of parts with special structures is crucial, which directly affects the assembly of the final product.
[0003] In the conventional preform shaping process of ceramic matrix composite flat plate parts, carbon cloth or silicon carbide cloth is stacked and laid on the surface of the die to form a preform, and only a machining allowance is reserved on the periphery. However, the preparation of ceramic matrix composite parts must be carried out through chemical vapor infiltration (CVI). Since the CVI temperature is relatively high, usually around 950-1200℃, the part will deform at high temperature during this process. During the preform preparation process, there is no deformation due to the action of the mold. When the density of the preform reaches 1.2-1.3g / cm 3 , the preform needs to be demolded to avoid serious mold sticking and affect the later chemical vapor infiltration of the preform. After the mold is removed, the density of the preform is 1.3-1.7g / cm 3 , and deformation such as plane distortion is prone to occur during the CVI densification process. The larger the size of the part, the more complex the deformation, and a special shape correcting tool or a new mold needs to be designed for deformation control. The use of a special shape correcting tool or mold for deposition preparation will affect the densification progress, thereby prolonging the production cycle and increasing the production cost. SUMMARY
[0004] In view of the deficiencies in the prior art, the present application provides a near-net forming die and a forming method for ceramic matrix composite flat plate parts, which solves the problem of deformation of the preform of the ceramic matrix composite part during chemical vapor infiltration in the prior art.
[0005] In the first aspect, in order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is: A near-net forming die for ceramic matrix composite flat plate parts, comprising an upper die assembly, a lower die assembly and a graphite clamp; the upper die assembly and the lower die assembly are detachably connected; the graphite clamp clamps and fixes the upper die assembly and the lower die assembly.
[0006] In the present scheme, the preform of the ceramic matrix composite part is arranged between the upper die assembly and the lower die assembly, and the graphite clamp clamps the upper die assembly and the lower die assembly, so that the preform can be vapor deposited together with the upper die assembly and the lower die assembly during subsequent chemical vapor deposition, thereby avoiding the high-temperature deformation of the preform during the early CVI vapor deposition and the later CVI densification process.
[0007] Further, the upper die assembly comprises an upper die and an upper frame body, the upper die is arranged inside the upper frame body, and a plurality of sewing holes are formed on the upper die; The lower die assembly comprises a lower die and a lower frame body, the lower die is arranged inside the lower frame body, and a plurality of sewing holes are formed on the lower die; The inner edges of the upper frame body and the lower frame body on the side close to each other are provided with steps, the use profile of the upper die is tightly attached to the step use profile of the inner edge of the upper frame body and the preform profile, and the use profile of the lower die is tightly attached to the step use profile of the inner edge of the lower frame body and the preform profile; screw holes are formed on the upper frame body and the lower frame body, and the upper frame body and the lower frame body are connected by die screws penetrating through the screw holes.
[0008] In the present scheme, the upper die and the upper frame body in the upper die assembly are designed in a split type, and the lower die and the lower frame body in the lower die assembly are designed in a split type, and when the density of the preform reaches 1.2-1.3 g / cm 3 Before the further CVI densification process, only the upper die and the lower die can be removed, and the upper frame body and the lower frame body can be retained; this design will not affect the CVI densification process of the preform, and due to the clamping effect of the upper frame body and the lower frame body, the preform will not be deformed in a plane twist manner, so that the shape of the prepared part can be ensured to be standard, and subsequent mechanical processing is easy.
[0009] Further, the graphite clamp comprises a first graphite pressing strip and a second graphite pressing strip, the first graphite pressing strip is arranged on the top of the upper die, and the second graphite pressing strip is arranged on the bottom of the lower die; the first graphite pressing strip and the second graphite pressing strip are connected by clamp screws.
[0010] In the present scheme, after loosening the clamp screws and removing the first graphite pressing strip and the second graphite pressing strip, the upper die and the lower die can be removed, which is convenient to operate.
[0011] In a second aspect, based on the near-net forming die for the ceramic matrix composite flat plate part provided in the first aspect, a near-net forming method for the ceramic matrix composite flat plate part is provided, which comprises the following steps: Step S1: design the preform structure; Step S2: cut the carbon cloth according to the preform structure, and uniformly lay the carbon cloth or silicon carbide cloth on the use profile of the lower die; Step S3: using carbon fiber to sew the laid carbon cloth or silicon carbide cloth to the using surface of the lower mold; Step S4: installing the lower frame around the lower mold; Step S5: installing the upper frame on the lower frame, and connecting the upper frame and the lower frame by using mold bolts after installation; Step S6: embedding the upper mold in the upper frame; Step S7: setting the first graphite pressing strip on the top of the upper mold, and setting the second graphite pressing strip on the bottom of the lower mold, and connecting the first graphite pressing strip and the second graphite pressing strip by using clamp bolts; Step S8: preparing the interface and the silicon carbide matrix for the whole composed of the prefabricated body, the lower mold and the upper mold; Step S9: preparing the silicon carbide matrix for the prefabricated body, and detecting the finished product after preparation.
[0012] In the scheme, the carbon cloth is prepared and sewn on the lower mold to form a shape, then the lower frame and the upper frame are installed, and the upper mold is embedded in the upper frame, so that the upper mold and the lower mold are highly matched in position. After the interface and the silicon carbide matrix are prepared by chemical vapor deposition, the upper mold and the lower mold are removed, and the densification of the prefabricated body matrix is carried out. The densification rate is relatively fast, the production cycle of the part is short, the cost is reduced, and the prefabricated body is not easy to deform during the densification process.
[0013] Further, when designing the prefabricated body structure in step S1, a 10-15mm allowance is reserved at the edge of the part.
[0014] Further, in step S2, the carbon cloth or silicon carbide cloth with the required thickness is uniformly laid on the using surface of the lower mold; it is required that the carbon cloth exceeds the edge of the mold by 5-10mm.
[0015] Further, in step S4, after the lower frame is installed around the lower mold, the inner edge step surface of the lower frame is reserved with an allowance of 1-2mm at the edge of the prefabricated body.
[0016] Further, in step S5, when installing the upper frame, it is required that the upper frame is flush with the lower frame around the edge, and the fitting gap is less than 0.1mm.
[0017] Further, in step S8, when preparing the interface and the silicon carbide matrix, after the density of the prefabricated body matrix reaches 1.2-1.3g / cm3, the deposition is stopped, the first graphite pressing strip and the second graphite pressing strip are removed, and the upper mold and the lower mold are taken off.
[0018] Further, step S9 comprises: Step S901: preparing the silicon carbide matrix for the prefabricated body, and removing the upper frame and the lower frame after the density of the prefabricated body matrix is greater than 1.7g / cm 3 ; Step S902: machining the preform according to the standard size of the part; Step S903: after machining, continue to prepare the silicon carbide matrix of the preform, and when the matrix density of the preform is greater than 1.85 g / cm 3 , perform finished product detection.
[0019] The beneficial effects of the present application are: The near net forming mold for ceramic matrix composite flat plate parts provided by the present application can perform vapor deposition on the preform together with the upper mold assembly and the lower mold assembly during subsequent chemical vapor deposition, avoiding high-temperature deformation of the preform during the early CVI vapor deposition and the later CVI densification process. During the CVI densification process, only the upper mold and the lower mold can be removed, and the upper frame and the lower frame are retained, so that the CVI densification process of the preform is not affected, and the preform does not deform due to the clamping effect of the upper frame and the lower frame. The shape of the prepared part is standard, and subsequent mechanical processing is easy.
[0020] The near net forming method for ceramic matrix composite flat plate parts provided by the present application prepares and sews carbon cloth on the lower mold, then installs the lower frame and the upper frame, and after installation, installs the upper mold, so that the upper mold and the lower mold are in high position matching. After preparing the interface and the silicon carbide matrix by chemical vapor deposition, the upper mold and the lower mold are removed, and then the densification of the preform matrix is performed. The densification rate is fast, the part production cycle is short, and the cost is reduced. Meanwhile, the preform is not prone to deformation during the densification process. BRIEF DESCRIPTION OF DRAWINGS
[0021] Figure 1 It is a structure diagram of the preform in the present application; Figure 2 It is an exploded view of the upper mold assembly and the lower mold assembly in the present application; Figure 3 It is a structure diagram of laying the preform on the lower mold in Example 2; Figure 4 It is a structure diagram of setting the lower frame around the lower mold in Example 2; Figure 5 It is a structure diagram of installing the upper frame on the lower frame in Example 2; Figure 6 It is a structure diagram of embedding the upper mold in the upper frame in Example 2; Figure 7 It is a structure diagram of clamping the upper mold and the lower mold by the graphite clamp in Example 2; Figure 8 It is a structure diagram of performing preform matrix densification after disassembling the upper mold and the lower mold.
[0022] Reference signs: 1. upper mold assembly; 11. upper mold; 12. upper frame body; 2. lower mold assembly; 21. lower mold; 22. lower frame body; 23. mold bolt; 24. step; 3. graphite clamp; 31. first graphite pressing strip; 32. second graphite pressing strip; 33. clamp bolt; DETAILED DESCRIPTION The present application will be further described below in conjunction with the drawings and specific embodiments. The specific embodiments of the present application are described below to facilitate understanding of the present application by those skilled in the art, but it should be clear that the present application is not limited to the scope of the specific embodiments, and that all applications utilizing the concept of the present application are within the scope of the present application as long as various changes are within the spirit and scope of the present application as defined and determined by the appended claims.
[0023] Example 1 As shown in Figure 2 and Figure 7 , the present embodiment provides a near net shape forming mold for ceramic matrix composite flat plate parts, which solves the problem of deformation of the preform during chemical vapor deposition of ceramic matrix composite parts in the prior art; it specifically comprises: The upper mold assembly 1, the lower mold assembly 2 and the graphite clamp 3; the upper mold assembly 1 and the lower mold assembly 2 are detachably connected; the graphite clamp 3 clamps and fixes the upper mold assembly 1 and the lower mold assembly 2; during subsequent chemical vapor deposition, the preform can be vapor deposited together with the upper mold assembly 1 and the lower mold assembly 2, avoiding high-temperature deformation of the preform during the early CVI and the late CVI densification process.
[0024] The upper mold assembly 1 comprises the upper mold 11 and the upper frame body 12, the upper mold 11 is arranged inside the upper frame body 12, and a 0.5mm gap is reserved between the upper mold 11 and the upper frame body 12; a plurality of sewing holes are formed on the upper mold 11, the diameter of the sewing hole is φ3-φ5mm, and the hole spacing is 5mm.
[0025] The lower mold assembly 2 comprises the lower mold 21 and the lower frame body 22, the lower mold 21 is arranged inside the lower frame body 22, and a 0.5mm gap is reserved between the lower mold 21 and the lower frame body 22; a plurality of sewing holes are formed on the lower mold 21, the diameter of the sewing hole is φ3-φ5mm, and the hole spacing is 5mm. The length and width dimensions of the upper mold 11 and the lower mold 21 are 5-10mm smaller than the size of the preform (part size + machining allowance).
[0026] The bottom surface of the upper mold 11 is flush with the bottom surface of the upper frame body 12, the bottom surface of the lower mold 21 is flush with the bottom surface of the lower frame body 22, and the inner and outer type four peripheral end surfaces of the upper frame body 12 and the lower frame body 22 are flush.
[0027] The inner edge of the upper frame body 12 and the inner edge of the lower frame body 22 near one side are provided with steps 24, the working surface of the upper die 11 is flush with the step 24 of the inner edge of the upper frame body 12, and the working surface of the lower die 21 is flush with the step 24 of the inner edge of the lower frame body 22. When the preform is clamped in use, the preform is arranged in the cavity formed by the steps 24 of the upper frame body 12 and the lower frame body 22, and the upper and lower surfaces of the preform are respectively attached to the working surface of the upper die 11 and the working surface of the lower die 21.
[0028] For parts like flat plates, the working surface of the upper die 11 may not be flush with the step 24 of the inner edge of the upper frame body 12 when a part with a curved surface is prepared, and the working surface of the lower die 21 may not be flush with the step 24 of the inner edge of the lower frame body 22.
[0029] The upper frame body 12 and the lower frame body 22 are provided with bolt holes, and the bolt holes are spaced apart by 150-200 mm; the upper frame body 12 and the lower frame body 22 are connected by a die bolt 23 penetrating through the bolt holes.
[0030] The upper die 11 and the upper frame body 12 in the upper die assembly 1 are designed in a split type, and the lower die 21 and the lower frame body 22 in the lower die assembly 2 are designed in a split type; after the density of the preform reaches 1.2-1.3 g / cm 3 Before the further CVI densification process, only the upper die 11 and the lower die 21 can be removed, and the upper frame body 12 and the lower frame body 22 are retained; this design does not affect the CVI densification process of the preform, and due to the clamping effect of the upper frame body 12 and the lower frame body 22, the preform will not deform in a plane distortion manner, which can ensure that the shape of the prepared part is standard, and subsequent machining is easy.
[0031] The graphite clamp 3 includes a first graphite pressing strip 31 and a second graphite pressing strip 32, the first graphite pressing strip 31 is arranged at the top of the upper die 11, and the second graphite pressing strip 32 is arranged at the bottom of the lower die 21; the first graphite pressing strip 31 and the second graphite pressing strip 32 are connected by a clamp bolt 33; after the clamp bolt 33 is loosened and the first graphite pressing strip 31 and the second graphite pressing strip 32 are removed, the upper die 11 and the lower die 21 can be taken down, which is convenient to operate.
[0032] Example 2 Based on the near-net forming die for a ceramic matrix composite flat plate part provided in Example 1, a near-net forming method for a ceramic matrix composite flat plate part is provided, which includes the following steps: Step S1: design a preform structure, reserve a 12 mm margin at the edge of the part, as shown in Figure 1 ; Step S2: Cutting 19 layers of T300-1K carbon cloth according to the structure of the preform, and uniformly laying the carbon cloth or silicon carbide cloth on the use surface of the lower mold 21; the carbon cloth is required to exceed the edge of the mold by at least 10 mm, as shown in Figure 3 . Step S3: Sewing the laid 1K carbon cloth or silicon carbide cloth on the use surface of the lower mold 21 using 3K carbon fiber; Step S4: Installing the lower frame 22 around the lower mold 21, and after installing the lower frame 22, the inner edge step surface of the lower frame 22 is reserved with a margin of 1-2 mm from the edge of the preform, as shown in Figure 4 . Step S5: Installing the upper frame 12 on the lower frame 22, and the upper frame 12 is required to be flush with the four edges of the lower frame 22, and the fitting gap is less than 0.1 mm; after installation, the upper frame 12 and the lower frame 22 are connected using mold bolts 23, as shown in Figure 5 . Step S6: Embedding the upper mold 11 in the upper frame 12, as shown in Figure 6 . Step S7: Setting the first graphite pressing strip 31 on the top of the upper mold 11, and setting the second graphite pressing strip 32 on the bottom of the lower mold 21, and connecting the first graphite pressing strip 31 and the second graphite pressing strip 32 through the clamp bolt 33, as shown in Figure 7 . Step S8: Preparing the carbon interface and the silicon carbide matrix for the whole composed of the preform, the lower mold 21 and the upper mold 11, and after the density of the preform matrix reaches 1.2-1.3 g / cm3, stopping deposition, removing the first graphite pressing strip 31 and the second graphite pressing strip 32, and taking off the upper mold 11 and the lower mold 21, as shown in Figure 8 . Step S9: Preparing the silicon carbide matrix for the preform, and after preparation, performing finished product detection; specifically including: Step S901: Preparing the silicon carbide matrix for the preform, and when the density of the preform matrix is greater than 1.7 g / cm3, removing the upper frame 12 and the lower frame 22; Step S902: Processing the preform according to the standard size of the part; Step S903: After processing, continuing to prepare the silicon carbide matrix for the preform, and when the density of the preform matrix is greater than 1.85 g / cm3, performing finished product detection.
[0033] In this embodiment, after preparing the carbon interface and the silicon carbide matrix by chemical vapor infiltration, the upper mold 11 and the lower mold 21 are removed, and then the densification of the preform matrix is performed, the densification rate is fast, the production cycle of the part is short, the cost is reduced, and the preform is not easy to deform during the densification process.
[0034] Those skilled in the art will appreciate that the embodiments described herein are presented for purposes of illustration and that the inventive principles are not limited to these particular embodiments. Other variations and modifications can be made to the embodiments without departing from the spirit and scope of the inventive principles.
Claims
1. A near-net-shape mold for ceramic-based composite flat plate parts, characterized by: It comprises an upper mold assembly (1), a lower mold assembly (2) and a graphite clamp (3); the upper mold assembly (1) and the lower mold assembly (2) are detachably connected; and the graphite clamp (3) clamps and fixes the upper mold assembly (1) and the lower mold assembly (2).
2. The near-net-shape mold for ceramic-based composite flat plate parts according to claim 1, characterized in that: The upper mold assembly (1) comprises an upper mold (11) and an upper frame (12); the upper mold (11) is arranged inside the upper frame (12); and a plurality of sewing holes are provided on the upper mold (11); The lower mold assembly (2) comprises a lower mold (21) and a lower frame (22); the lower mold (21) is arranged inside the lower frame (22); and a plurality of sewing holes are provided on the lower mold (21); The inner edges of the sides of the upper frame (12) and the lower frame (22) that are close to each other are both provided with a step (24); the use profile of the upper mold (11) and the use profile of the step (24) on the inner edge of the upper frame (12) are both in close contact with the prefabricated body surface; the use profile of the lower mold (21) and the use profile of the step (24) on the inner edge of the lower frame (22) are both in close contact with the prefabricated body surface; bolt holes are both provided on the upper frame (12) and the lower frame (22); the upper frame (12) and the lower frame (22) are connected by mold bolts (23) that pass through the bolt holes.
3. The near-net-shape mold for ceramic-based composite flat plate parts according to claim 2, characterized in that: The graphite clamp (3) includes a first graphite bead (31) and a second graphite bead (32), wherein the first graphite bead (31) is arranged on the top of the upper mold (11), and the second graphite bead (32) is arranged on the bottom of the lower mold (21); the first graphite bead (31) and the second graphite bead (32) are connected by a clamp bolt (33).
4. A method for forming a near-net-shape mold for a ceramic-based composite flat plate part according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S1: designing a prefabricated structure; Step S2: cutting the carbon cloth according to the preform structure, and evenly laying the carbon cloth or silicon carbide cloth on the working surface of the lower mold (21); Step S3: using carbon fiber to sew the laid carbon cloth or silicon carbide cloth onto the use surface of the lower mold (21); Step S4: installing the lower frame (22) around the lower mold (21); Step S5: Install the upper frame (12) on the lower frame (22), and after installation, use mold bolts (23) to connect the upper frame (12) and the lower frame (22); Step S6: embedding the upper mold (11) inside the upper frame (12); Step S7: a first graphite strip (31) is provided on the top of the upper mold (11), a second graphite strip (32) is provided on the bottom of the lower mold (21), and the first graphite strip (31) and the second graphite strip (32) are connected by a clamp bolt (33); Step S8: preparing the interface and silicon carbide matrix of the preform together with the lower mold (21) and the upper mold (11); Step S9: preparing a silicon carbide matrix for the preform, and then testing the finished product.
5. The method for forming a near-net-shape mold for a ceramic-based composite flat plate part according to claim 4, characterized in that: When designing the prefabricated structure in step S1, a margin of 10 to 15 mm is reserved at the edge of the part.
6. The method for forming a near-net-shape mold for a ceramic-based composite flat plate part according to claim 4, characterized in that: In step S2, the carbon cloth or silicon carbide cloth is cut to a required thickness and evenly laid on the working surface of the lower mold (21); the carbon cloth is required to extend at least 5 to 10 mm beyond the edge of the mold.
7. The method for forming a near-net-shape mold for a ceramic-based composite flat plate part according to claim 4, characterized in that: In step S4, after the lower frame (22) is installed around the lower mold (21), a margin of 1-2 mm is reserved between the inner edge step surface of the lower frame (22) and the edge of the preform.
8. The method for forming a near-net-shape mold for a ceramic-based composite flat plate part according to claim 4, characterized in that: In the step S5, when the upper frame (12) is installed, it is required that the edges of the upper frame (12) and the lower frame (22) are flush with each other, and the gap between them is less than 0.1 mm.
9. The method for forming a near-net-shape mold for a ceramic-based composite flat plate part according to claim 4, characterized in that: In step S8, the interface and the silicon carbide matrix are prepared until the density of the preform matrix reaches 1.2 to 1.3 g / cm 3 Afterwards, the deposition is stopped, the first graphite strip (31) and the second graphite strip (32) are removed, and the upper mold (11) and the lower mold (21) are removed.
10. The method for forming a near-net-shape mold for a ceramic-based composite flat plate part according to claim 4, characterized in that: The step S9 includes: Step S901: Prepare a silicon carbide matrix for the preform until the matrix density of the preform is greater than 1.7 g / cm 3 When the upper frame (12) and the lower frame (22) are removed; Step S902: Processing the preform according to the standard size of the part; Step S903: After processing, continue to prepare the silicon carbide matrix of the preform until the matrix density of the preform is greater than 1.85g / cm 3 When the product is finished, it is tested.