Preparation method of ceramic matrix composite high-strength disassembly groove countersunk head screw

Abstract

The invention discloses a preparation method of a ceramic matrix composite countersunk head screw with a high-strength disassembly groove, and relates to the technical field of preparation of countersunk head screws. The method sequentially comprises the following steps of: CVI (Chemical Vapor Infiltration) of a plate; processing a strip material; performing CVI (chemical vapor infiltration) deposition; turning a bar material; densification holes are manufactured, and threads are turned; a PIP-PCS is carried out; performing CVI (chemical vapor infiltration) deposition; carrying out adaptive installation; the balance is removed; manufacturing a dismounting groove / hole; and performing CVI deposition to obtain a finished product. The invention provides a PIP + CVI combined forming process technology aiming at the defects and defects of densification of a countersunk head part dismounting groove / hole in a traditional process, and effectively solves the problems of edge breakage and other defects existing in the screw countersunk head part dismounting groove / hole and the dismounting, mounting and tightening process.

Description

Technical Field

[0001] This invention relates to the field of countersunk screw manufacturing technology, specifically to a method for preparing a high-strength countersunk screw with a disassembly groove made of ceramic matrix composite material. Background Technology

[0002] Ceramic matrix composites are a new type of strategic material with characteristics such as high temperature resistance, low density, high specific strength, high specific modulus, oxidation resistance, ablation resistance, insensitivity to cracks, and non-catastrophic damage. They have wide applications in aviation, aerospace, satellite spaceflight, nuclear energy, and photovoltaic fields.

[0003] Due to limitations in the molding process of ceramic matrix composite countersunk screw preforms, the current fabrication method for countersunk screw preforms is mostly three-dimensional needle-punched (carbon fiber) flat plates. It is difficult to achieve conformal fabrication of countersunk screws. The common CVI deposition process for countersunk screws has drawbacks such as uneven density of the disassembly groove in the countersunk part and easy edge chipping damage in the disassembly groove, which makes it difficult to meet the online connection accuracy requirements of ceramic matrix composites. Therefore, it is crucial to adopt certain measures and methods to improve the fabrication quality of the disassembly groove in ceramic matrix composite countersunk screws. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a method for preparing a high-strength countersunk screw with a countersunk groove made of ceramic matrix composite material, thereby solving the problems of insufficient and inadequate densification of the countersunk groove / hole in existing countersunk screws.

[0005] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for preparing a high-strength countersunk screw with a disassembly groove made of ceramic matrix composite material is provided, comprising the following steps: (1) Plate CVI: A silicon carbide matrix is ​​deposited on a flat ceramic matrix preform using CVI until the density by drainage method is 1.5-1.6 g / cm³. 3 This yields a flat preform; (2) Processing strips: Along the layup direction of the ceramic matrix composite preform, the flat preform is processed into strips. The length of the strip is 10-12 mm longer than the total length of the countersunk screw, and the thickness and width of the strip are 0.8-1 mm greater than the maximum countersunk diameter of the countersunk screw. (3) CVI deposition: Silicon carbide substrate is deposited on the strip using CVI until the density by drainage method is 1.7-1.8 g / cm³. 3 The strip preform is obtained; (4) Turning bar stock: On a CNC lathe, the strip preform is processed into round bar stock, and then processed into "convex" shaped stepped round bar stock. The diameter of the large diameter section of the stepped round bar stock is the same as the maximum diameter of the countersunk head of the countersunk screw. The diameter of the small diameter section of the stepped round bar stock is 0.2-0.5mm larger than the nominal diameter of the screw of the countersunk screw. The length of the small diameter section of the stepped round bar stock is 0.2-0.5mm larger than the length of the screw of the countersunk screw. The length of the stepped round bar stock is 10mm more than the total length of the countersunk screw. The part of the stepped round bar stock that is 10mm longer than the length of the countersunk screw is used as the process head for subsequent processes. (5) Making denser holes and machining threads: On a CNC lathe, two densification holes are machined on the large-diameter section of the stepped round bar. The diameter of each densification hole is 3mm, and both holes are through holes. The first densification hole is located on the axis of the large-diameter section of the stepped round bar and is perpendicular to the layup direction of the ceramic matrix composite preform. The second densification hole is located on the axis of the large-diameter section of the stepped round bar and is perpendicular to the first densification hole. The edge of both densification holes is 0.5-1mm away from the countersunk end face of the countersunk screw. Then, on a CNC lathe, the thread, nominal diameter of the screw, total length, screw length, and countersunk head are machined to obtain the first semi-finished product. (6) PIP-PCS: The countersunk head and process head of the first semi-finished product are immersed in a slurry solution and then cured to obtain ceramic matrix composite parts; (7) CVI deposition: CVI deposition of silicon carbide matrix is ​​used to deposit silicon carbide matrix on ceramic matrix composite parts until the density by drainage method is 2-2.1 g / cm³. 3 The second semi-finished product is obtained; (8) Adaptation and installation: Adapt and install the second semi-finished product; (9) Remove excess material: Remove the exposed process head of the adapter installation, retain the connection between the core of the process head and the countersunk end face, with a connection diameter of 3-3.5mm, to obtain the third semi-finished product; (10) Making disassembly groove / hole: Remove the third semi-finished product from the fitting installation position, remove the process head, and prepare the disassembly groove / hole on the countersunk end face to obtain the fourth semi-finished product; (11) CVI deposition: Silicon carbide is deposited using CVI to obtain the finished product.

[0006] Based on the above technical solution, the present invention can be further improved as follows: Furthermore, in step (6), the minimum distance between the edge of the two densification holes and the countersunk end face of the countersunk screw is 0.5-1mm.

[0007] Furthermore, in step (6), the slurry solution is prepared by heating polycarbosilane in a water bath, adding dicumyl peroxide, and stirring.

[0008] Furthermore, the mass ratio of polycarbosilane to dicumyl peroxide is 100:0.3.

[0009] Furthermore, the sample was heated in a water bath at 25°C for 30 minutes.

[0010] Furthermore, in step (6), the sample is immersed for 20 minutes at 0.5 MPa.

[0011] Furthermore, in step (6), the product is kept at 160°C for 2 hours to complete the curing process.

[0012] Furthermore, in step (10), the disassembly groove / hole is a straight groove, a double-hole groove, or a cross groove.

[0013] Furthermore, in step (11), deposition lasts for 40-45 hours.

[0014] The present invention has the following beneficial effects: 1. In view of the shortcomings and drawbacks of the densification of the countersunk head disassembly groove / hole in the traditional process, the present invention proposes the PIP+CVI combined molding process technology, which effectively solves the problems of edge chipping and other defects in the disassembly groove / hole of the screw countersunk head during disassembly and tightening.

[0015] 2. The present invention has a short preparation cycle. The PIP process can effectively solve the problems of poor deposition and penetration effect of traditional CVI process on thick preforms and high brittleness of ceramic matrix composites. In the process of preparing countersunk screws by traditional CVI process, multiple furnaces of repeated deposition are required for the countersunk part with large size, resulting in a long preparation cycle and obvious density gradient decay in the radial direction of the countersunk part. The present invention can make the part secondary denser by PIP impregnation-curing and then CVI-SiC deposition, and the internal SiC matrix is ​​more dense and uniform.

[0016] 3. This invention is applicable to the machining of screws with various countersunk angles (90°, 60°, and 55°), and provides better integrity of the disassembly area (slotted groove, double-hole groove). The countersunk screws of this invention have density-enhancing holes created during the manufacturing process, resulting in more uniform density in the countersunk area, which is more beneficial for ensuring the quality of the finished product. Furthermore, after installation, these density-enhancing holes can be used as process disassembly holes, facilitating the removal of the flattened head after disassembly and improving repair efficiency. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of the present invention; Figure 2 Schematic diagram of a prefabricated flat countersunk screw; Figure 3 This is a schematic diagram of the countersunk screw strip structure; Figure 4 Schematic diagram of countersunk screw bar stock; Figure 5 This is a schematic diagram of the first semi-finished product of a countersunk screw; Figure 6 This is a schematic diagram of a finished countersunk screw with a countersunk head angle of 90°, as shown in Example 1. Figure 7 This is a schematic diagram of a finished countersunk screw with a countersunk head angle of 60°, as shown in Example 2. Figure 8 This is a schematic diagram of the finished product of the double-groove countersunk screw with a countersunk angle of 55° as shown in Example 3; Figure 9 Here is a microscopic image of the countersunk screw prepared in Example 1; Figure 10 This is a microscopic image of a slotted countersunk screw manufactured using the traditional CVI process. Detailed Implementation

[0018] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0019] Figures 2-8 In this diagram, Dk is the maximum countersunk diameter; D is the nominal diameter of the screw; L is the total length; B is the screw length; E is the thread length; α is the countersunk angle; and M is the thread specification.

[0020] CVI: Chemical Vapor Deposition; PIP: Precursor Impregnation Pyrolysis.

[0021] Example 1: A high-strength countersunk screw with a ceramic matrix composite material has an M6 thread specification, a total length L of 20mm, a screw length B of 17mm, a thread length E of 10mm, a countersunk angle α of 90°, a maximum countersunk diameter Dk of 12mm, and a nominal screw diameter D of 6mm.

[0022] A method for preparing a high-strength countersunk screw with a detachable groove made of ceramic matrix composite material includes the following steps: (see process flow diagram) Figure 1 ) (1) Plate CVI: A flat ceramic matrix composite preform (see Figure 2 , Figure 2 (From top to bottom, the images are a top view and a front view.) A silicon carbide substrate was deposited using CVI, with a density of 1.6 g / cm³ obtained by the drainage method. 3 This yields a flat preform; (2) Processing strips: Along the layup direction of the ceramic matrix composite preform, the flat preform is processed into strips. The length of the strip is 10 mm longer than the total length of the countersunk screw, and the thickness and width of the strip are both 1 mm greater than the maximum countersunk diameter of the countersunk screw. The strips are then obtained (see...). Figure 3 , Figure 3 (From left to right, the front view and the side view are arranged as follows). Specifically: 2.1. Machining the upper and lower surfaces of the ceramic matrix composite preform plate on a surface grinder, with the allowance evenly distributed on both sides, ensuring that the thickness of the ceramic matrix composite preform plate is 13mm; 2.2 The ceramic matrix composite preform plate is processed into strips along the orthogonal direction of its shape. The strips are 30mm long, and the thickness and width of the strips are both 13mm. (3) CVI deposition: Silicon carbide substrate is deposited on the strip using CVI until the density by drainage method is 1.78 g / cm³. 3 The strip preform is obtained; (4) Turning bar stock: On a CNC lathe, the strip preform is installed on a four-jaw chuck, the dial indicator is used for alignment, and diamond tools are used to chamfer the strip stock into round bar stock; Then, the round bar is mounted onto the three-jaw chuck of the CNC lathe, aligned using a dial indicator, and machined into a "convex" shaped stepped round bar. The diameter of the major diameter section of the stepped round bar is the same as the maximum countersunk diameter of the countersunk screw, φ12mm. The diameter of the minor diameter section of the stepped round bar is φ6.5mm, which is 0.5mm larger than the nominal diameter of the countersunk screw. The length of the minor diameter section of the stepped round bar is 17.5mm, which is 0.5mm longer than the length of the countersunk screw. The length of the stepped round bar is 30mm, which is 10mm longer than the total length of the countersunk screw. The portion of the stepped round bar that is 10mm longer than the total length of the countersunk screw is the process head for subsequent processes (see...). Figure 4 ); (5) Making denser holes and machining threads: On a CNC lathe, two densification holes are machined on the large-diameter section of the stepped round bar. The diameter of each densification hole is 3mm, and both holes are through holes. The first densification hole is located on the axis of the large-diameter section of the stepped round bar and is perpendicular to the layup direction of the ceramic matrix composite preform. The second densification hole is located on the axis of the large-diameter section of the stepped round bar and is perpendicular to the first densification hole. The minimum distance between the edge of the two densification holes and the countersunk end face of the countersunk screw is 1mm. Then, on a CNC lathe, the threads, nominal diameter of the screw, overall length, screw length, and countersunk head are machined to obtain the first semi-finished product (see...). Figure 5 , Figure 5 (From left to right, the front view and the side view are arranged as follows). (6) PIP-PCS: The countersunk head and process head of the first semi-finished product are immersed in slurry solution. After the vacuum degree is reduced to -0.01Mpa, the slurry solution is vacuum-inhaled into the impregnation tank through the feed port. The pressure valve is opened to start pressure impregnation. The product is impregnated at 0.5Mpa for 20 minutes, then removed and drained. Then it is kept at 160℃ for 2 hours to complete the curing and obtain ceramic matrix composite parts. The slurry solution was prepared by heating polycarbosilane in a water bath at 25°C for 30 minutes, adding dicumyl peroxide, and stirring. The mass ratio of polycarbosilane to dicumyl peroxide was 100:0.3. (7) CVI deposition: CVI deposition of silicon carbide matrix is ​​used to deposit silicon carbide matrix on ceramic matrix composite parts until the density by drainage method is 2 g / cm³. 3 The second semi-finished product is obtained; (8) Adaptation and installation: The second semi-finished product is adapted and installed, that is, the screw of the second semi-finished product is tested and matched with the thread to be adapted, and the countersunk conical surface is tested and matched with the countersunk 90° countersunk hole to be installed. (9) Remove excess material: Remove the exposed process head of the adapter installation, retain the connection between the core of the process head and the countersunk end face, with a connection diameter of 3mm, to obtain the third semi-finished product; (10) Making disassembly groove: Using the densification holes orthogonally distributed in the countersunk part as process auxiliary disassembly holes, the third semi-finished product is removed from the matching installation position, the process head is removed, and a disassembly groove (a straight groove, perpendicular to the layup direction) is prepared on the countersunk end face to obtain the fourth semi-finished product. (11) CVI deposition: The fourth semi-finished product is subjected to CVI deposition for one furnace of silicon carbide for 40 hours to obtain the finished product (see Figure 6 and Figure 9 , Figure 6 From left to right, the main view and the side view are shown in the middle.

[0023] Example 2: A high-strength countersunk screw with a ceramic matrix composite material has an M8 thread specification, a total length L of 18 mm, a screw length B of 14 mm, a thread length E of 10 mm, a countersunk angle α of 60°, a maximum countersunk diameter Dk of 12.6 mm, and a nominal screw diameter D of 8 mm.

[0024] A method for preparing a high-strength countersunk screw with a detachable groove made of ceramic matrix composite material includes the following steps: (1) Plate CVI: A silicon carbide matrix is ​​deposited on a flat ceramic matrix preform using CVI until the density by drainage method is 1.5 g / cm³. 3 This yields a flat preform; (2) Processing the strip material: Along the laying direction of the ceramic matrix composite preform, process the flat preform into a strip material. The length of the strip material is greater than the total length of the countersunk screw by 12 mm, and the thickness and width of the strip material are both greater than the maximum diameter of the countersunk head of the countersunk screw by 0.9 mm, thus obtaining the strip material; Specifically: 2.1. Process the upper and lower surfaces of the flat ceramic matrix composite preform on a surface grinder, evenly distributing the allowance on both sides to ensure the thickness dimension of the flat ceramic matrix composite preform is 13.5 mm; 2.2. Process the flat ceramic matrix composite preform into a strip material along the orthogonal direction of the outer shape. The length of the strip material is 30 mm, and the thickness and width dimensions of the strip material are both 13.5 mm; (3) CVI deposition: Use CVI to deposit a silicon carbide matrix on the strip material until the density by the drainage method is 1.7 g / cm 3 , thus obtaining the strip preform; (4) Turning the bar material: On a CNC lathe, install the strip preform onto a four-jaw chuck, use a dial indicator to align it, and use a diamond tool to chamfer the strip material into a round bar; Then install the round bar onto a three-jaw chuck of the CNC lathe, use a dial indicator to align it, and process the round bar into a "convex" shaped stepped round bar. The diameter of the large-diameter section of the stepped round bar is the same as the maximum diameter of the countersunk head of the countersunk screw, which is φ12.6 mm. The diameter of the small-diameter section of the stepped round bar is greater than the nominal diameter of the screw rod of the countersunk screw by 0.2 mm, which is φ8.2 mm. The length of the small-diameter section of the stepped round bar is greater than the length of the screw rod of the countersunk screw by 0.2 mm, which is 14.2 mm. The length of the stepped round bar is 10 mm more than the total length of the countersunk screw, which is 28 mm; The part with a length 10 mm more of the stepped round bar is the process head for subsequent processes; (5) Making densification holes and threading: On a CNC lathe, process two densification holes on the large-diameter section of the stepped round bar. The diameter of each densification hole is 3 mm, and all the densification holes are through holes. Among them, the first densification hole is set on the axis of the large-diameter section of the stepped round bar and perpendicular to the laying direction of the ceramic matrix composite preform. The second densification hole is set on the axis of the large-diameter section of the stepped round bar and perpendicularly intersects with the first densification hole. The minimum distance from the hole edge of the two densification holes to the countersunk end face of the countersunk screw is 0.5 mm; Then, on a CNC lathe, process the thread, the nominal diameter of the screw rod, the total length, the length of the screw rod, and the countersunk head to obtain the first semi-finished product; (6) PIP-PCS: Immerse the countersunk head and the process head of the first semi-finished product in the slurry solution. After the vacuum degree reaches -0.01 Mpa, vacuum suck the slurry solution into the impregnation tank through the feed port, open the pressure valve, start pressure impregnation, impregnate for 20 min under the condition of 0.5 Mpa, take it out and drain; Then keep it warm at 160 °C for 2 h to complete curing, thus obtaining the ceramic matrix composite part; The slurry solution was prepared by heating polycarbosilane in a water bath at 25°C for 30 minutes, adding dicumyl peroxide, and stirring. The mass ratio of polycarbosilane to dicumyl peroxide was 100:0.3. (7) CVI deposition: CVI deposition of silicon carbide matrix is ​​used to deposit silicon carbide matrix on ceramic matrix composite parts until the density by drainage method is 2 g / cm³. 3 The second semi-finished product is obtained; (8) Adaptation and installation: The second semi-finished product is adapted and installed, that is, the screw of the second semi-finished product is tested and matched with the thread to be adapted, and the countersunk conical surface is tested and matched with the countersunk 60° countersunk hole to be installed. (9) Remove excess material: Remove the exposed process head of the adapter installation, retain the connection between the core of the process head and the countersunk end face, with a connection diameter of 3.5mm, to obtain the third semi-finished product; (10) Making disassembly groove: Using the densification holes orthogonally distributed in the countersunk part as process auxiliary disassembly holes, the third semi-finished product is removed from the matching installation position, the process head is removed, and a disassembly groove (a straight groove, perpendicular to the layup direction) is prepared on the countersunk end face to obtain the fourth semi-finished product. (11) CVI deposition: The fourth semi-finished product is subjected to CVI deposition for one furnace of silicon carbide for 45 hours to obtain the finished product (see Figure 7 , Figure 7 From left to right, the main view and the side view are shown in the middle.

[0025] Example 3: A high-strength countersunk screw with a ceramic matrix composite material has an M8 thread specification, a total length L of 18 mm, a screw length B of 14 mm, a thread length E of 10 mm, a countersunk angle α of 55°, a maximum countersunk diameter Dk of 12.2 mm, and a nominal screw diameter D of 8 mm.

[0026] A method for preparing a high-strength countersunk screw with a detachable groove made of ceramic matrix composite material includes the following steps: (1) Plate CVI: A silicon carbide matrix is ​​deposited on a flat ceramic matrix preform using CVI until the density by drainage method is 1.55 g / cm³. 3 This yields a flat preform; (2) Processing strips: Along the layup direction of the ceramic matrix composite preform, the flat preform is processed into strips. The length of the strip is 11 mm longer than the total length of the countersunk screw, and the thickness and width of the strip are both greater than the maximum countersunk diameter of the countersunk screw by 0.8 mm. Specifically: 2.1. Machining the upper and lower surfaces of the ceramic matrix composite preform plate on a surface grinder, with the allowance evenly distributed on both sides, ensuring that the thickness of the ceramic matrix composite preform plate is 13mm; 2.2. Process the ceramic matrix composite preform plate into strips along the orthogonal direction of the outer shape. The length of the strip is 29 mm, and the thickness and width dimensions of the strip are both 13 mm; (3)CVI deposition: Use CVI to deposit silicon carbide matrix on the strip until the density by the drainage method is 1.8 g / cm 3 , and obtain the strip preform; (4)Turn the bar stock: On a CNC lathe, install the strip preform on a four-jaw chuck, use a dial indicator to align it, and use a diamond tool to chamfer the strip into a round bar stock; Then install the round bar stock on a three-jaw chuck of the CNC lathe, use a dial indicator to align it, and process the round bar stock into a "convex" shaped stepped round bar stock. The diameter of the large-diameter section of the stepped round bar stock is the same as the maximum diameter of the countersunk head of the countersunk screw, which is φ12.2 mm. The diameter of the small-diameter section of the stepped round bar stock is 0.3 mm larger than the nominal diameter of the screw of the countersunk screw, which is φ8.3 mm. The length of the small-diameter section of the stepped round bar stock is 0.3 mm longer than the length of the screw of the countersunk screw, which is 14.3 mm. The length of the stepped round bar stock is 10 mm longer than the total length of the countersunk screw, which is 28 mm; The part with a length 10 mm longer of the stepped round bar stock is the process head for subsequent processes; (5)Manufacture densification holes and turn threads: On a CNC lathe, process two densification holes on the large-diameter section of the stepped round bar stock. The diameter of each densification hole is 3 mm, and all densification holes are through holes. Among them, the first densification hole is set on the axis of the large-diameter section of the stepped round bar stock and perpendicular to the lay-up direction of the ceramic matrix composite preform. The second densification hole is set on the axis of the large-diameter section of the stepped round bar stock and perpendicularly intersects with the first densification hole. The minimum distance from the hole edge of the two densification holes to the countersunk end face of the countersunk screw is 0.8 mm; Then, on a CNC lathe, process threads, the nominal diameter of the screw, the total length, the length of the screw, and the countersunk head, and obtain the first semi-finished product; (6)PIP-PCS: Immerse the countersunk head and process head of the first semi-finished product in the slurry solution. After the vacuum degree reaches -0.01 Mpa, vacuum suck the slurry solution into the impregnation tank through the feed port, open the pressure valve, start pressure impregnation, impregnate for 20 min under the condition of 0.5 Mpa, and take it out to drain; Then keep it warm at 160 °C for 2 h to complete curing, and obtain the ceramic matrix composite part; The slurry solution is prepared by the following method: Heat polycarbosilane in a water bath at 25 °C for 30 min, add diisopropylbenzene peroxide, and stir to obtain it; The mass ratio of polycarbosilane to diisopropylbenzene peroxide is 100:0.3; (7)CVI deposition: Use CVI to deposit silicon carbide matrix on the ceramic matrix composite part until the density by the drainage method is 2.1 g / cm 3 , and obtain the second semi-finished product; (8) Adaptation and installation: The second semi-finished product is adapted and installed, that is, the screw of the second semi-finished product is tested and matched with the thread to be adapted, and the countersunk conical surface is tested and matched with the countersunk 55° countersunk hole to be installed. (9) Remove excess material: Remove the exposed process head of the adapter installation, retain the connection between the core of the process head and the countersunk end face, with a connection diameter of 3.3mm, to obtain the third semi-finished product; (10) Making disassembly holes: Using the orthogonally distributed densification holes in the countersunk part as process-aided disassembly holes, the third semi-finished product is removed from the matching installation position, the process head is removed, and a disassembly groove (double hole groove, perpendicular to the layup direction) is prepared on the countersunk end face to obtain the fourth semi-finished product. (11) CVI deposition: The fourth semi-finished product is subjected to CVI deposition for one furnace of silicon carbide for 42 hours to obtain the finished product (see Figure 8 , Figure 8 From left to right, the main view and the side view are shown in the middle.

[0027] Comparative Example 1: A ceramic matrix composite countersunk screw has an M6 thread specification, a total length L of 20 mm, a screw length B of 17 mm, a thread length E of 10 mm, a countersunk angle α of 90°, a maximum countersunk diameter Dk of 12 mm, and a nominal screw diameter D of 6 mm.

[0028] A method for preparing a countersunk screw made of ceramic matrix composite material includes the following steps: Excluding steps (5) and (6), the rest is the same as in Example 1, and the finished product is obtained (see Figure 10 ).

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a ceramic matrix composite high-strength socket head screw, characterized by, Comprise the following steps in sequence: (1) Sheet CVI: plate-shaped ceramic matrix composite preform is deposited with SiC matrix by CVI to a drainage method density of 1.5-1.6 g / cm 3 , to obtain a plate-shaped preform; (2) Processing strip: along the ceramic matrix composite preform layer direction, the flat plate preform is processed into a strip, the length of the strip is 10-12mm longer than the total length of the countersunk screw, the thickness and width of the strip are both 0.8-1mm larger than the maximum diameter of the countersunk head of the countersunk screw, and the strip is prepared; (3) CVI deposition: the strip is deposited with SiC matrix by CVI to a drainage method density of 1.7-1.8 g / cm 3 , to obtain a strip preform; (4) Bar stock: on the numerical control lathe, the strip preform is processed into a round bar, and then into a " convex" shaped stepped round bar, the diameter of the large diameter section of the stepped round bar is the same as the maximum diameter of the countersunk head of the countersunk screw, the diameter of the small diameter section of the stepped round bar is 0.2-0.5mm larger than the nominal diameter of the screw rod of the countersunk screw, the length of the small diameter section of the stepped round bar is 0.2-0.5mm longer than the length of the screw rod of the countersunk screw, the length of the stepped round bar is 10mm longer than the total length of the countersunk screw, and the part with a length of 10mm longer than the stepped round bar is used as the process head for the subsequent process; (5) Make densification holes and thread: On the numerical control lathe, two densification holes are processed on the large diameter section of the stepped round bar, the hole diameter of the densification holes is 3mm, and the densification holes are through holes, wherein the first densification hole is arranged on the axis of the large diameter section of the stepped round bar and is perpendicular to the layering direction of the ceramic matrix composite preform, the second densification hole is arranged on the axis of the large diameter section of the stepped round bar and intersects perpendicularly with the first densification hole, and the hole edge of the two densification holes is 0.5-1mm away from the countersunk head end surface of the countersunk screw; then, on the numerical control lathe, the thread, the nominal diameter of the screw rod, the total length, the length of the screw rod and the countersunk head are processed to prepare the first semi-finished product; (6) PIP-PCS: immerse the countersunk head and the process head of the first semi-finished product in the slurry solution, and then solidify to prepare the ceramic matrix composite part; (7) CVI deposition: the ceramic matrix composite part is deposited with silicon carbide matrix by CVI, until the drainage method density is 2-2.1 g / cm 3 , to obtain a second semi-finished product; (8) Fit and install: fit and install the second semi-finished product; (9) Remove the excess amount: remove the process head exposed by the fit and installation, retain the connection between the process head core and the countersunk head end surface, the connection diameter is 3-3.5mm, and the third semi-finished product is prepared; (10) Make disassembly groove / hole: remove the process head from the fit and installation position, prepare the disassembly groove / hole on the countersunk head end surface to prepare the fourth semi-finished product; (11) CVI deposition: deposit silicon carbide on the fourth semi-finished product by CVI to prepare the finished product.

2. The method of making a ceramic matrix composite high strength captive slot button head screw of claim 1, wherein, In step (6), the slurry solution is prepared by the following method: heating the polycarbosilane in a water bath, adding dicumyl peroxide, and stirring to prepare.

3. The method of making a ceramic matrix composite high strength captive slot button head screw of claim 2, wherein, The mass ratio of polycarbosilane to dicumyl peroxide is 100:0.

3.

4. The method of making a ceramic matrix composite high strength captive slot button head screw of claim 2, wherein, Water bath heating at 25℃ for 30min.

5. The method of making a ceramic matrix composite high strength captive slot flat head screw of claim 1, wherein, In step (6), immerse for 20min under the condition of 0.5Mpa.

6. The method of making a ceramic matrix composite high strength captive slot button head screw of claim 1, wherein, In step (6), the solidification is completed under the condition of 160℃ for 2h.

7. The method of making a ceramic matrix composite high strength captive slot button head screw of claim 1, wherein, In step (11), deposit for 40-45h.

8. The ceramic matrix composite high-strength disassembly groove countersunk screw prepared by the method of any one of claims 1-7.

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