A method for preparing a carbon fiber surface club-shaped SiOC / C two-stage interface coating

Abstract

The present application relates to the technical field of carbon fiber surface modification, and particularly relates to a preparation method of a carbon fiber surface wolf tooth rod-shaped SiOC / C double-stage interface coating. A uniform protrusion carbon is first prepared on the surface of the carbon fiber by using a hydrothermal carbonization method, and then SiO2, Si and C powders are used as raw materials to complete the preparation of the wolf tooth rod-shaped SiOC / C double-stage interface coating by using a chemical vapor deposition method. In the present application, the carbon coating is prepared on the surface of the carbon fiber by using a hydrothermal carbonization process, which can alleviate the damage of the carbon fiber in the gas phase deposition process, and then the outer layer of the coating structure is converted into a SiOC coating by using a chemical vapor deposition method, and the SiOC coating can effectively isolate the oxidation corrosion. The wolf tooth rod-shaped SiOC / C double-stage interface structure prepared by the present application can form an inlaid pinning structure between the carbon fiber and the matrix, greatly improves the interface bonding force, and provides an efficient and convenient way to improve the comprehensive performance of the carbon / toughened ceramic composite material.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber surface modification technology, specifically to a method for preparing a serrated SiOC / C bi-level interface coating on the surface of carbon fiber. Background Technology

[0002] Carbon fiber, with its excellent mechanical properties and low density, is a typical reinforcing phase material in ceramic matrix composites, and carbon / ceramic composites prepared from it are among the most promising materials in the aerospace and nuclear energy fields. Interfacial properties are a key factor affecting the performance of carbon / ceramic composites. A good interfacial phase material can not only protect carbon fibers from reactive damage but also optimize the interfacial bonding between carbon fibers and the matrix. Among various interfacial phase materials, carbon interfacial phases, due to their similar physical properties to carbon fibers, can effectively avoid interfacial cracking or fiber breakage caused by expansion mismatch under thermal conditions, making them one of the preferred interfacial phase materials for carbon / ceramic composites. However, due to the poor oxidation resistance of carbon materials, a single-layer carbon interfacial phase is difficult to effectively isolate oxidative erosion; moreover, carbon interfacial coatings are usually relatively smooth with low roughness, resulting in poor and difficult-to-control frictional properties between them and the matrix or fibers. If an interfacial phase with both good oxidation resistance and mechanical frictional properties is prepared on top of the carbon coating, the oxidation resistance and mechanical properties of the carbon / ceramic composite can be improved simultaneously.

[0003] Currently, grafting zero-dimensional nanoparticles, one-dimensional nanowires, or nanofibers onto the surface of carbon fibers is widely used to improve their interfacial properties. Surface grafts can form an interlocking structure between the matrix and the substrate, significantly enhancing interfacial adhesion. However, grafting methods struggle to achieve a completely uniform coating on carbon fibers, making it difficult to effectively improve their antioxidant properties. Furthermore, grafting methods generally suffer from complex processes, high costs, and poor uniformity, hindering their engineering applications. Therefore, a simple, easily scalable method for preparing a surface coating that effectively ensures the antioxidant properties of carbon fibers is a pressing issue that needs to be addressed. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a mahogany-shaped SiOC / C bi-level interface coating on the surface of carbon fibers, in order to solve the problems of existing grafting methods, such as complex processes, high costs, poor uniformity, difficulty in engineering applications, and difficulty in ensuring the antioxidant properties of carbon fibers.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for preparing a serrated SiOC / C bi-level interface coating on a carbon fiber surface, comprising the following steps:

[0006] S1. Place the carbon fiber braid in a tube furnace and keep it at 500℃~700℃ for 1 hour to remove the sizing agent from the surface of the carbon fiber.

[0007] S2. Immerse the carbon fiber braid after removing the sizing agent into a glucose solution and transfer it to a hydrothermal reactor. Place the reactor in an oven and set the oven temperature to 160℃~210℃. After keeping it warm for 4~6 hours, take out the carbon fiber braid and use an ultrasonic cleaner to repeatedly clean the carbon fiber braid to obtain a carbon fiber braid with uniformly attached tiny carbon balls on the surface.

[0008] S3. Immerse the carbon fiber braid obtained in S2 in the catalyst solution. After 5-10 hours, remove the carbon fiber braid and place it in an oven at 70°C until it is completely dry.

[0009] S4. Mix SiO2, Si and C powder raw materials evenly in a certain proportion and spread them evenly at the bottom of the alumina crucible. Cover the mixed powder with the carbon fiber braid obtained in S3. Then place the alumina crucible in a tube furnace, heat it under a protective atmosphere and then keep it at that temperature for a period of time to obtain the carbon fiber braid with SiOC / C dual-level interface coating.

[0010] Furthermore, in S2, the glucose solution has a mass fraction of 30 wt.% to 60 wt.%.

[0011] Furthermore, in S3, the catalyst can be one of ferric nitrate, nickel nitrate, or ferrocene.

[0012] Furthermore, in S3, the concentration of the catalyst solution is 0.01 mol / L to 1 mol / L.

[0013] Furthermore, in S4, the powder raw materials of SiO2, Si and C are mixed evenly by a high-energy ball mill, and the molar ratio of Si and C elements in the powder raw materials of SiO2, Si and C is 1:1 to 5.

[0014] Furthermore, in S4, the protective gas is either argon or nitrogen, and the flow rate is 300 mL / min.

[0015] Furthermore, in step S4, the tube furnace is uniformly heated to 1200°C at a rate of 5°C / min.

[0016] ~1600℃, heat preservation time is 2h~4h.

[0017] The beneficial effects of this invention are:

[0018] 1. The present invention uses a hydrothermal carbonization process to prepare a carbon coating structure with serrated protrusions on the surface of carbon fibers. Then, through chemical vapor deposition, the outer layer of the coating structure is transformed into an inorganic ceramic interface with surface protrusions, which can effectively alleviate the damage to carbon fibers caused by the vapor deposition process.

[0019] 2. The wolf-tooth-shaped SiOC / C bi-level interfacial coating prepared by the present invention can not only increase the interfacial shear force between carbon fibers and the matrix, but also effectively improve the oxidation damage resistance of carbon fibers, thereby achieving a synergistic improvement in the interfacial performance and oxidation resistance of carbon fibers. Attached Figure Description

[0020] Figure 1 This is a low-magnification SEM (scanning electron microscope) image of the bi-stage coating obtained in Example 1 of the present invention;

[0021] Figure 2 This is a high-magnification SEM image of the dual-stage coating obtained in Example 1 of the present invention;

[0022] Figure 3 This is a high-magnification SEM image of the dual-stage coating obtained in Example 1 of the present invention;

[0023] Figure 4 This is a high-magnification SEM image of the dual-stage coating obtained in Example 1 of the present invention;

[0024] Figure 5 This is the EDS (elemental analysis) diagram of the dual-stage coating obtained in Example 1 of the present invention. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0026] The principle of this invention is as follows:

[0027] The sizing agent (one or more film-forming polymers) on the surface of the carbon fiber braid can affect the preparation of the carbon coating, so it needs to be removed. In a tube furnace, holding at a temperature of 500℃~700℃ for 1 hour can vaporize and remove the sizing agent, thus facilitating the uniform preparation of the subsequent carbon coating.

[0028] Under high temperature conditions, glucose undergoes decomposition, which can form a carbon coating on the carbon fiber surface. The hydrothermal method is used to make the carbon coating more uniform. During the process, the oven temperature in the hydrothermal reactor is controlled at 160℃~210℃ and kept at that temperature for 4~6 hours. After ultrasonic cleaning, a carbon coating structure containing wolf-tooth-shaped protrusions is obtained.

[0029] Take powdered raw materials of SiO2, Si and C, and control the molar ratio of Si to C to be 1:1 to 5 during the process. Mix them evenly with a ball mill and spread them evenly on the bottom of an alumina crucible. Cover the mixed powder with the carbon-coated carbon fiber braid. Then place the alumina crucible in a tube furnace and heat it to 1200℃ to 1600℃ under a protective atmosphere. Then hold it at that temperature for 2h to 4h to obtain the carbon fiber braid with a SiOC / C dual-level interface coating.

[0030] During the process, an alumina crucible and a protective gas atmosphere are used to avoid introducing impurities and high-temperature oxidation of carbon fibers. The protective gas is an inert gas, such as nitrogen or argon. At the same time, in order to improve the reaction rate, the carbon fibers need to be impregnated with a catalyst. During the process, the carbon fiber braid with the prepared carbon coating structure is impregnated in a catalyst solution. The catalyst solution is ferric nitrate, nickel nitrate, ferrocene, etc., and the solution concentration is controlled at 0.01 mol / L to 1 mol / L.

[0031] Example 1

[0032] S1. Place the carbon fiber braid in a corundum tube furnace and keep it at 500°C for 1 hour to remove the sizing agent from the surface of the carbon fiber.

[0033] S2. Prepare a 40 wt.% glucose solution with a glucose to deionized water mass ratio of 2:3. Stir the solution in a magnetic stirrer until the glucose is fully dissolved. Immerse the carbon fibers (after removing the sizing agent) in the solution, and then perform a hydrothermal reaction at 200℃ for 6 hours in an oven to prepare a carbon coating. Ultrasonically clean the fibers after the hydrothermal reaction using an ultrasonic cleaner to evenly disperse the large number of carbon spheres attached to the braid, obtaining a uniformly carbon-coated C / C ratio. f Fiber braided fabric;

[0034] S3. Immerse the carbon fiber braid obtained in S2 in a 0.01 mol / L ferric nitrate solution for 10 hours, then remove and dry it.

[0035] S4. Mix SiO2, Si, and C powders at a Si to C molar ratio of 1:4 and ball mill in a high-energy ball mill at 220 r / min for 30 min to obtain a uniformly mixed raw material powder. Spread the uniformly mixed raw material powder evenly in an alumina crucible, cover the crucible with a fiber braid obtained in S3, and heat to 1500℃ for 2 h under argon protection at a heating rate of 5℃ / min and an argon flow rate of 300 ml / min. After the holding period, cool with the furnace to obtain a carbon fiber braid with a SiOC / C dual-level interface coating.

[0036] The obtained SiOC / C bi-level interfacial coating on the carbon fiber braid was subjected to scanning electron microscopy (SEM) and elemental analysis (EDS). The results are as follows: Figures 1-5 As shown.

[0037] like Figure 1 As shown, the bi-level interfacial coating prepared on the carbon fiber surface exhibits a wolf-tooth-like structure, in which the "wolf-tooth" protrusions are evenly and widely distributed.

[0038] like Figures 2-4 As shown, the double-layer coating on the carbon fiber surface has a uniform thickness and a dense structure.

[0039] like Figure 5 As shown, the elemental composition of the dual-layer coating was analyzed by EDS, and it can be seen that the main elemental components are Si, O and C.

[0040] Example 2

[0041] S1. Place the carbon fiber braid in a corundum tube furnace and keep it at 500°C for 1 hour to remove the sizing agent from the surface of the carbon fiber.

[0042] S2. Prepare a 50 wt.% glucose solution with a glucose to deionized water mass ratio of 1:1. Stir the solution in a magnetic stirrer until the glucose is fully dissolved. Immerse the carbon fibers (after removing the sizing agent) in the solution, and then perform a hydrothermal reaction at 190℃ for 6 hours in an oven to prepare a carbon coating. Ultrasonic cleaning is then used to clean the fibers after the hydrothermal reaction, dispersing the large number of carbon spheres attached to the braid evenly, resulting in a uniformly carbon-coated C / C ratio. f Fiber braided fabric;

[0043] S3. Immerse the carbon fiber braid obtained in S2 in a 0.05 mol / L ferric nitrate solution for 10 hours, then remove and dry it.

[0044] S4. Mix SiO2, Si, and C powders at a Si to C molar ratio of 1:3 and ball mill in a high-energy ball mill at 220 r / min for 30 min to obtain a uniformly mixed raw material powder. Spread the uniformly mixed raw material powder evenly in an alumina crucible, cover the crucible with a fiber braid obtained in S3, and heat to 1400℃ for 2 h under argon protection at a heating rate of 5℃ / min and an argon flow rate of 300 ml / min. After the holding time is completed, cool with the furnace to obtain a carbon fiber braid with a SiOC / C dual-level interface coating.

[0045] Example 3:

[0046] S1. Place the carbon fiber braid in a corundum tube furnace and keep it at 500°C for 1 hour to remove the sizing agent from the surface of the carbon fiber.

[0047] S2. Prepare a 60 wt.% glucose solution with a glucose to deionized water mass ratio of 3:2. Stir the solution in a magnetic stirrer until the glucose is fully dissolved. Immerse the carbon fibers (after removing the sizing agent) in the solution, and then perform a hydrothermal reaction at 190°C for 6 hours in an oven to prepare a carbon coating. Ultrasonic cleaning is then used to clean the fibers after the hydrothermal reaction, dispersing the large number of carbon spheres attached to the braid evenly, resulting in a uniformly carbon-coated C / C ratio. f Fiber braided fabric;

[0048] S3. Immerse the carbon fiber braid obtained in S2 in a 0.1 mol / L ferric nitrate solution for 10 hours, then remove and dry it.

[0049] S4. Mix SiO2, Si, and C powders at a Si to C molar ratio of 1:2 and ball mill in a high-energy ball mill at 220 r / min for 30 min to obtain a uniformly mixed raw material powder. Spread the uniformly mixed raw material powder evenly in an alumina crucible, cover the crucible with a fiber braid obtained in S3, and heat to 1600℃ for 2 h under argon protection at a heating rate of 5℃ / min and an argon flow rate of 300 ml / min. After the holding period, cool with the furnace to obtain a carbon fiber braid with a SiOC / C dual-level interface coating.

[0050] Example 4

[0051] S1. Place the carbon fiber braid in a corundum tube furnace and keep it at 500°C for 1 hour to remove the sizing agent from the surface of the carbon fiber.

[0052] S2. Prepare a 30 wt.% glucose solution with a glucose to deionized water mass ratio of 3:7. Stir the solution in a magnetic stirrer until the glucose is fully dissolved. Immerse the carbon fibers (after removing the sizing agent) in the solution, and then perform a hydrothermal reaction at 200°C for 6 hours in an oven to prepare a carbon coating. Ultrasonic cleaning is then used to clean the fibers after the hydrothermal reaction, dispersing the large number of carbon spheres attached to the braid evenly, resulting in a uniformly carbon-coated C / C ratio. f Fiber braided fabric;

[0053] S3. Immerse the carbon fiber braid obtained in S2 in a 0.5 mol / L ferrocene solution for 10 hours, then remove and dry it.

[0054] S4. Mix SiO2, Si, and C powders at a Si to C molar ratio of 1:5 and ball mill in a high-energy ball mill at 220 r / min for 30 min to obtain a uniformly mixed raw material powder. Spread the uniformly mixed raw material powder evenly in an alumina crucible, cover the crucible with a fiber braid obtained in S3, and heat to 1500℃ for 2 h under argon protection at a heating rate of 5℃ / min and an argon flow rate of 300 ml / min. After the holding period, cool with the furnace to obtain a carbon fiber braid with a SiOC / C dual-level interface coating.

[0055] Example 5

[0056] S1. Place the carbon fiber braid in a corundum tube furnace and keep it at 500°C for 1 hour to remove the sizing agent from the surface of the carbon fiber.

[0057] S2. Prepare a 40 wt.% glucose solution with a glucose to deionized water mass ratio of 2:3. Stir the solution in a magnetic stirrer until the glucose is fully dissolved. Immerse the carbon fibers (after removing the sizing agent) in the solution, and then perform a hydrothermal reaction at 200℃ for 6 hours in an oven to prepare a carbon coating. Ultrasonically clean the fibers after the hydrothermal reaction using an ultrasonic cleaner to evenly disperse the large number of carbon spheres attached to the braid, obtaining a uniformly carbon-coated C / C ratio. f Fiber braided fabric;

[0058] S3. Immerse the carbon fiber braid obtained in S2 in a 0.01 mol / L ferric nitrate solution for 10 hours, then remove and dry it.

[0059] S4. Mix SiO2, Si, and C powders at a Si to C molar ratio of 1:3 and ball mill in a high-energy ball mill at 220 r / min for 30 min to obtain a uniformly mixed raw material powder. Spread the uniformly mixed raw material powder evenly in an alumina crucible, cover the crucible with a fiber braid obtained in S3, and heat to 1300℃ for 2 h under argon protection at a heating rate of 5℃ / min and an argon flow rate of 300 ml / min. After the holding period, cool with the furnace to obtain a carbon fiber braid with a SiOC / C dual-level interface coating.

[0060] Example 6

[0061] S1. Place the carbon fiber braid in a corundum tube furnace and keep it at 500°C for 1 hour to remove the sizing agent from the surface of the carbon fiber.

[0062] S2. Prepare a 40 wt.% glucose solution with a glucose to deionized water mass ratio of 1:1. Stir the solution in a magnetic stirrer until the glucose is fully dissolved. Immerse the carbon fibers (after removing the sizing agent) in the solution, and then perform a hydrothermal reaction at 200°C for 6 hours in an oven to prepare a carbon coating. Ultrasonically clean the fibers after the hydrothermal reaction using an ultrasonic cleaner to evenly disperse the large number of carbon spheres attached to the braid, obtaining a uniformly carbon-coated C / C ratio. f Fiber braided fabric;

[0063] S3. Immerse the carbon fiber braid obtained in S2 in a 0.01 mol / L ferric nitrate solution for 10 hours, then remove and dry it.

[0064] S4. Mix SiO2, Si, and C powders at a Si to C molar ratio of 1:1 and ball mill in a high-energy ball mill at 220 r / min for 30 min to obtain a uniformly mixed raw material powder. Spread the uniformly mixed raw material powder evenly in an alumina crucible, cover the crucible with a fiber braid obtained in S3, and heat to 1200℃ for 2 h under argon protection at a heating rate of 5℃ / min and an argon flow rate of 300 ml / min. After the holding period, cool with the furnace to obtain a carbon fiber braid with a SiOC / C dual-level interface coating.

[0065] To analyze the performance of this bilayer interface, interfacial shear force tests were conducted on the original fibers and the carbon fibers with the serrated SiOC / C bilevel interfacial coating prepared in the examples. The results showed that the interfacial shear strength of the original carbon fibers was 16.6 MPa, the carbon fibers obtained in Example 1 were 20.4 MPa, the carbon fibers obtained in Example 2 were 42.2 MPa, the carbon fibers obtained in Example 3 were 30.7 MPa, and the carbon fibers obtained in Example 4 were 21.7 MPa. The test results indicate that the serrated SiOC / C bilevel interfacial coating prepared in this invention can increase the interfacial shear force between the carbon fibers and the matrix.

[0066] This invention is not limited to the preferred embodiments described above. Anyone can derive other forms of products under the guidance of this invention. However, regardless of any changes made in their shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A method for preparing a carbon fiber surface club-like SiOC / C bi-level interface coating, characterized by, The method comprises the following steps: S1, placing the carbon fiber braid in a tube furnace, and keeping the temperature at 500-700 DEG C for 1 h to remove the sizing agent on the surface of the carbon fiber; S2, immersing the carbon fiber braid after removing the sizing agent in a glucose solution, and transferring to a hydrothermal reaction kettle, placing the reaction kettle in an oven, setting the oven temperature to 160-210 DEG C, keeping for 4-6 h, taking out the carbon fiber braid, and repeatedly cleaning the carbon fiber braid using an ultrasonic cleaning machine to obtain a carbon fiber braid with uniform and small carbon spheres attached to the surface; S3, immersing the carbon fiber braid obtained in S2 in a catalyst solution, taking out the carbon fiber braid after 5-10 h, and placing it in an oven at 70 DEG C until completely dry; S4, uniformly mixing SiO2, Si and C powder raw materials in a certain proportion, laying them on the bottom of an alumina crucible, and covering the carbon fiber braid obtained in S3 on the mixed powder, then placing the alumina crucible in a tube furnace, and heating and keeping for a period of time in a protective gas atmosphere to obtain a carbon fiber braid with SiOC / C double-level interface coating.

2. The method of claim 1, wherein the method is characterized by: In S2, the mass fraction of the glucose solution is 30-60 wt.%.

3. The method for preparing a serrated SiOC / C bipolar interface coating on a carbon fiber surface according to claim 1, characterized in that: In S3, the catalyst is one of ferric nitrate, nickel nitrate and ferrocene.

4. The method for preparing a serrated SiOC / C bipolar interface coating on a carbon fiber surface according to claim 3, characterized in that: In S3, the concentration of the catalyst solution is 0.01-1 mol / L.

5. The method for preparing a serrated SiOC / C bipolar interface coating on a carbon fiber surface according to claim 1, characterized in that: In S4, the SiO2, Si and C powder raw materials are uniformly mixed by a high-energy ball mill, and the molar ratio of Si and C in the SiO2, Si and C powder raw materials is 1:1-5.

6. The method of claim 1, wherein the method is characterized by: In S4, the protective gas is argon with a flow rate of 300 mL / min.

7. The method for preparing a serrated SiOC / C bipolar interface coating on a carbon fiber surface according to claim 1, characterized in that: In S4, the tube furnace is uniformly heated at a rate of 5 DEG C / min to 1200-1600 DEG C, and the holding time is 2-4 h.

Images