Preparation method of two-dimensional C / SiC composite material with short compact period
Two-dimensional C/SiC composite materials were prepared by ball milling, alkaline washing and modification of silicon carbide particles, combined with polycarbosilane and peroxide initiators. This solved the problems of long preparation cycle and high cost, and realized high performance and low cost two-dimensional C/SiC composite materials.
Patent Information
- Application Number
- CN202512059863.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-03-06
AI Technical Summary
Existing methods for preparing C/SiC composite materials cannot simultaneously achieve short production cycles, low costs, and high mechanical properties; conventional processes suffer from long production cycles and high costs.
Two-dimensional C/SiC composite materials were prepared by ball milling, alkali washing and modification of silicon carbide particles, combined with polycarbosilane and peroxide initiator, and then composited with carbon fiber fabric through slit coating, followed by multiple layers of curing and pyrolysis.
Short-cycle densification of two-dimensional C/SiC composites was achieved, significantly improving mechanical properties, reducing preparation costs, and requiring only 1-3 curing-pyrolysis processes.
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Figure CN121609588A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of ceramic matrix composites technology, and in particular to a method for preparing a two-dimensional C / SiC composite material with a short dense period. Background Technology
[0002] Due to their extremely high thermal stability and specific strength, ceramic matrix composites are widely used in thermal structures and thermal protection in fields such as aircraft and nuclear energy. Among ceramic matrix composites, carbon fiber reinforced silicon carbide composites are the most widely used. Besides aerospace and related military applications, since 2020, C / SiC has begun to be gradually used in high-end automotive brake discs. However, the high manufacturing cost and lengthy production cycle have become obstacles to further market expansion, severely limiting their widespread application.
[0003] Conventional C / SiC fabrication processes include precursor impregnation-pyrolysis (PIP), chemical vapor deposition (CVI), and liquid-phase silicon infiltration (LSI). In the PIP process, 8-12 rounds of repeated precursor impregnation-pyrolysis are often required to achieve densification of C / SiC, which significantly extends the fabrication cycle. Furthermore, the market price of conventional SiC liquid precursors is typically above 4000 RMB / kg, while the precursor utilization rate in the PIP process is only around 20% (final product mass / precursor mass consumed), further increasing the fabrication cost of C / SiC. Benefiting from low fiber damage and high density, the CVI method can bring superior mechanical properties to C / SiC; however, its process cost and cycle time even exceed those of the PIP method. In conventional PIP and CVI processes, the densification cycle for C / SiC can reach hundreds or even thousands of hours. The LSI method is one of the lowest-cost methods for preparing C / SiC; however, the liquid molten elemental silicon can damage carbon fibers at high temperatures, resulting in poor mechanical properties in C / SiC prepared by this method. Furthermore, conventional C / SiC reinforcements are based on 3D carbon fiber braids, which adds extra braiding costs.
[0004] Therefore, there is a need for a two-dimensional C / SiC composite material and its preparation method that can take into account short cycle time, low cost, and high mechanical properties. Summary of the Invention
[0005] The purpose of this invention is to provide a method for preparing a short-dense-cycle two-dimensional C / SiC composite material, in order to solve the problem that existing methods for preparing C / SiC composite materials cannot simultaneously achieve short cycle, low cost, and high mechanical properties.
[0006] To achieve the above objectives, the present invention provides a method for preparing a two-dimensional C / SiC composite material with a short dense period, comprising the following steps: S1. After mixing silicon carbide ceramic powder with water, the mixture is ball-milled and dried. Then, it is placed in potassium hydroxide solution and washed with alkali to obtain alkali-washed silicon carbide particles. S2. The alkaline-washed silicon carbide particles are placed in a vinyl silane coupling agent solution for dispersion treatment. The dispersed mixture is then heated for modification reaction to obtain vinyl-modified silicon carbide particles. S3. Dissolve polycarbosilane, vinyl polycarbosilane, and peroxide initiator in n-hexane, then add vinyl-modified silicon carbide particles to the mixed solution, stir, and rotary evaporate to obtain the coating precursor. S4. The coating precursor is combined with carbon fiber fabric to form a prepreg by using slit coating. S5. The prepreg is laminated and cured, and then pyrolyzed under vacuum or protective atmosphere to obtain a pre-dense C / SiC composite material. S6. Impregnate the pre-dense C / SiC composite material, and repeat the lamination curing and pyrolysis steps in S5 1-2 times to obtain a two-dimensional C / SiC composite material.
[0007] In this invention, the particle size of silicon carbide ceramic powder in S1 is 5-25µm, the mass ratio of silicon carbide ceramic powder to water is 1:5-10, the ball milling machine is a star ball mill, the ball milling speed is 500-700rpm, and the ball milling time is 10-15h; after ball milling, the particle size of silicon carbide ceramic powder is 200-800nm.
[0008] In this invention, the concentration of potassium hydroxide solution in S1 is 0.5-1.5 mol / L, the temperature of alkaline washing is 40-50℃, the washing time is 12-24 h, and stirring is carried out during the alkaline washing process at a stirring rate of 1200-2000 rpm. After the alkaline washing is completed, the mixed solution is centrifuged to separate the precipitate. The precipitate is washed with deionized water 3-5 times, and the centrifugation and washing steps are repeated 3-5 times. The precipitate is collected and dried at a temperature of 80-95℃ to obtain alkaline-washed silicon carbide particles.
[0009] In this invention, the vinyl silane coupling agent solution in S2 is an aqueous solution of vinyl silane coupling agent, which includes at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, and vinyltriisopropoxysilane. The mass concentration of the vinyl silane coupling agent solution is 2%-5%. The dispersion process includes sequential cross-ultra-high-speed shear dispersion and ultrasonic vibration. The modification reaction temperature is 40-60℃, the modification reaction time is 10-24h, and the modification reaction is accompanied by stirring at a speed of 1200-2000rpm. After the modification reaction is completed, the mixed solution is centrifuged to separate the precipitate. The precipitate is washed with deionized water 3-5 times, and the centrifugation and washing steps are repeated 3-5 times. The precipitate is collected and dried at a temperature of 80-95℃ to obtain vinyl-modified silicon carbide particles.
[0010] In this invention, the vinyl polycarbosilane in S3 is in a liquid state with a viscosity of 30-100 cps; the polycarbosilane is in a solid state; and the mass ratio of polycarbosilane to vinyl polycarbosilane is 5:4-6.
[0011] In this invention, the peroxide initiator in S3 includes cumene peroxide or benzoyl peroxide, and the mass of the peroxide initiator is 0.5%-1% of the mass of vinyl polycarbosilane; the volume of vinyl-modified silicon carbide particles accounts for 20%-40% of the total volume of polycarbosilane and vinyl polycarbosilane; the peak temperature of rotary evaporation is 80-95°C, and the pressure of rotary evaporation is 0.05-1 kPa. The purpose of rotary evaporation is to remove the above-mentioned n-hexane to obtain a high-viscosity coating precursor.
[0012] In this invention, the carbon fiber fabric in S4 includes a 2D fabric of T300 carbon fiber or a 2D fabric of T700 carbon fiber. The 2D fabric of T300 carbon fiber is selected from plain weave fabric, twill fabric or satin fabric of T300 carbon fiber; the 2D fabric of T700 carbon fiber is selected from plain weave fabric, twill fabric or satin fabric of T700 carbon fiber.
[0013] In this invention, the curing method in S5 includes vacuum bag pressing, autoclave method or molding method, the initiation temperature of curing is 120-140℃, and the peak temperature of curing is 180-250℃; the pyrolysis atmosphere includes nitrogen or argon, and the peak temperature of pyrolysis is 900-1400℃.
[0014] In this invention, the impregnation method in S6 is pressure impregnation, the pressure of pressure impregnation is 3-5 MPa, and the number of repetitions is 1-2 times.
[0015] The present invention also provides a two-dimensional C / SiC composite material prepared by the above-mentioned method for preparing short-dense period two-dimensional C / SiC composite material.
[0016] The present invention has the following beneficial effects: This invention provides a method for preparing a short-dense periodic two-dimensional C / SiC composite material, comprising the following steps: S1, mixing silicon carbide ceramic powder with water, ball milling, drying, and then placing it in a potassium hydroxide solution for alkaline washing to obtain alkaline-washed silicon carbide particles; S2, placing the alkaline-washed silicon carbide particles in a vinyl silane coupling agent solution for dispersion treatment, heating the dispersed mixture for modification reaction to obtain vinyl-modified silicon carbide particles; S3, mixing polycarbosilane, vinyl polycarbosilane, and... Oxide initiator is dissolved in n-hexane, and then vinyl-modified silicon carbide particles are added to the mixed solution. The mixture is stirred and rotary evaporated to obtain a coating precursor. S4: The coating precursor is combined with carbon fiber fabric to form a prepreg by slit coating. S5: The prepreg is laminated and cured, and then pyrolyzed under vacuum or protective atmosphere to obtain a pre-dense C / SiC composite material. S6: The pre-dense C / SiC composite material is impregnated, and the lamination curing and pyrolysis steps in S5 are repeated 1-2 times to obtain a two-dimensional C / SiC composite material.
[0017] In step S1, the ball milling process increases the specific surface area of the silicon carbide ceramic powder and simultaneously achieves micro-oxidation of the surface, laying the foundation for the subsequent alkaline washing process in step S2. Subsequently, the addition of potassium hydroxide solution enables the grafting of hydroxyl groups onto the surface of the silicon carbide ceramic powder, laying the foundation for the modification process in step S3. By adding vinyl polycarbosilane to combine with the hydroxyl groups on the surface of the silicon carbide ceramic powder, the resulting vinyl-modified silicon carbide particles not only increase compatibility with polycarbosilane but also significantly improve the mechanical properties of the subsequent two-dimensional C / SiC composite material.
[0018] The preparation method provided by this invention only requires 1-3 curing (layer curing)-pyrolysis processes to prepare two-dimensional C / SiC composite materials with high density and excellent mechanical properties. Compared with the traditional precursor impregnation pyrolysis method (which requires 9-12 rounds of densification cycle), it has the characteristics of short preparation cycle, low cost and excellent mechanical properties.
[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0020] Figure 1 This is a scanning electron microscope image of silicon carbide ceramic powder particles obtained in Example 1; Figure 2 This is the three-point bending force-displacement curve diagram of the present invention. Detailed Implementation
[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The features mentioned above or the features mentioned in the specific examples of this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.
[0022] The T300-3K plain weave fabric used in the following examples is a plain weave fabric of T300 strength grade carbon fiber, with 3000 carbon fiber monofilaments in a single bundle of fiber.
[0023] Example 1 A method for preparing a two-dimensional C / SiC composite material with a short dense period includes the following steps: S1. Silicon carbide ceramic powder with an average particle size of 5µm was mixed with water at a mass ratio of 1:5 and placed in a planetary ball mill. The mixture was ball-milled at 700rpm for 10h and then dried at 95℃ to obtain silicon carbide ceramic powder particles with an average particle size of 290nm. The silicon carbide ceramic powder particles were placed in a 1mol / L potassium hydroxide solution. After the silicon carbide ceramic powder particles were completely submerged, they were alkali-washed at 1600rpm for 12h at 40℃. After alkali washing, the mixed solution was centrifuged to separate the precipitate. The precipitate was washed with deionized water 3 times and the above centrifugation and washing steps were repeated 4 times. The precipitate was collected and placed in a blower dryer and dried at 95℃ to obtain alkali-washed silicon carbide particles. S2. The alkaline-washed silicon carbide particles were placed in a 5% (w / w) aqueous solution of vinyltrimethoxysilane to completely immerse them. Subsequently, they were subjected to cross-high-speed shear dispersion treatment and ultrasonic vibration treatment. After treatment, the particles were modified at 40°C and 1600 rpm for 12 hours. After the modification reaction was completed, the mixed solution was centrifuged to separate the precipitate. The precipitate was washed with deionized water 4 times, and the above centrifugation and washing steps were repeated 4 times. The precipitate was collected and placed in a forced-air drying oven and dried at 95°C to obtain vinyl-modified silicon carbide particles.
[0024] S3. Solid polycarbosilane, liquid vinyl polycarbosilane (30 cps), and cumene peroxide are mixed in a mass ratio of 1:1:0.01 and dissolved in n-hexane to obtain a polycarbosilane solution. Then, vinyl-modified silicon carbide particles (the volume of the vinyl-modified silicon carbide particles accounts for 40% of the total volume of solid polycarbosilane and liquid vinyl polycarbosilane) are added and stirred. Subsequently, the solution is rotary evaporated at a peak temperature of 80°C and a pressure of 1 kPa to remove n-hexane and obtain the coating precursor. S4. The coating precursor is coated into a thin film by slit coating and then combined with T300-3K plain weave fabric to form a prepreg. S5. The prepreg is laminated and cured using an autoclave. The initiation temperature for lamination and curing is 120℃, and the peak temperature is 180℃. The laminated and cured composite material is then pyrolyzed under a nitrogen atmosphere. The pyrolysis process is as follows: first, the temperature is increased from 20℃ to 200℃ at a rate of 3℃ / min, and held for 30 min; then, the temperature is increased to 250℃ at a rate of 1.6℃ / min, and held for 30 min; finally, the temperature is increased to 300℃ at a rate of 1.6℃ / min. The temperature was increased to 400℃ at a rate of 1.6℃ / min and held for 30 min; then increased to 600℃ at a rate of 1.2℃ / min and held for 60 min; subsequently increased to 800℃ at a rate of 1.6℃ / min and held for 60 min; finally increased to 1200℃ at a rate of 1.6℃ / min and held for 60 min to complete the pyrolysis process and obtain a preliminarily dense C / SiC composite material. S6. The pre-dense C / SiC composite material is impregnated under a nitrogen atmosphere at a pressure of 3 MPa. Then, step S5 above is repeated with the same parameters to obtain a two-dimensional C / SiC composite material with a density of 1.98 g / cm³. 3 .
[0025] That is, Example 1 underwent a total of two curing (layer curing)-pyrolysis processes.
[0026] Comparative Example 1 S1. Silicon carbide ceramic powder with an average particle size of 5µm was mixed with water and placed in a planetary ball mill. It was ball milled at 700rpm for 10h and then dried at 95℃ to obtain silicon carbide ceramic powder particles with an average particle size of 290nm. S2. Solid polycarbosilane, liquid vinyl polycarbosilane (30 cps), and cumene peroxide are mixed in a mass ratio of 1:1:0.01 and dissolved in n-hexane to obtain a polycarbosilane solution. Then, vinyl-modified silicon carbide particles (the volume of the vinyl-modified silicon carbide particles accounts for 40% of the total volume of solid polycarbosilane and liquid vinyl polycarbosilane) are added and stirred. Subsequently, the solution is rotary evaporated at a peak temperature of 80°C and a pressure of 1 kPa to remove n-hexane and obtain the coating precursor. S3. The coating precursor is coated into a thin film by slit coating and then combined with T300-3K plain weave fabric to form a prepreg. S4. The prepreg is laminated and cured using an autoclave. The initiation temperature for lamination and curing is 120℃, and the peak temperature is 180℃. The laminated and cured composite material is then pyrolyzed under a nitrogen atmosphere. The pyrolysis process is as follows: first, the temperature is increased from 20℃ to 200℃ at a rate of 3℃ / min, and held for 30 min; then, the temperature is increased to 250℃ at a rate of 1.6℃ / min, and held for 30 min; finally, the temperature is increased to 300℃ at a rate of 1.6℃ / min. The temperature was increased to 400℃ at a rate of 1.6℃ / min and held for 60 min; then increased to 600℃ at a rate of 1.2℃ / min and held for 60 min; subsequently increased to 800℃ at a rate of 1.6℃ / min and held for 60 min; finally increased to 1200℃ at a rate of 1.6℃ / min and held for 60 min to complete the pyrolysis process and obtain a preliminarily dense C / SiC composite material. S5. The preliminarily dense C / SiC composite material is impregnated under a nitrogen atmosphere at a pressure of 3 MPa. Then, step S4 above is repeated with the same parameters to obtain a two-dimensional C / SiC composite material with a density of 1.95 g / cm³. 3 .
[0027] That is, Comparative Example 1 underwent a total of two curing (layer curing)-pyrolysis processes.
[0028] Comparative Example 2 S1. Solid polycarbosilane, liquid vinyl polycarbosilane (30 cps), and cumene peroxide are mixed in a mass ratio of 1:1:0.01 and dissolved in n-hexane to obtain a polycarbosilane solution. Then, the solution is removed by rotary evaporation at a peak temperature of 80°C and a pressure of 1 kPa to obtain the coating precursor. S2. The coating precursor is coated into a thin film using slit coating and then combined with T300-3K plain weave fabric to form a prepreg. S3. The prepreg is laminated and cured using an autoclave. The initiation temperature for lamination and curing is 120℃, and the peak temperature is 180℃. The laminated and cured composite material is then pyrolyzed under a nitrogen atmosphere. The pyrolysis process is as follows: first, the temperature is increased from 20℃ to 200℃ at a rate of 3℃ / min, and held for 30 min; then, the temperature is increased to 250℃ at a rate of 1.6℃ / min, and held for 30 min; finally, the temperature is increased to 300℃ at a rate of 1.6℃ / min. The temperature was increased to 400℃ at a rate of 1.6℃ / min and held for 60 min; then increased to 600℃ at a rate of 1.2℃ / min and held for 60 min; subsequently increased to 800℃ at a rate of 1.6℃ / min and held for 60 min; finally increased to 1200℃ at a rate of 1.6℃ / min and held for 60 min to complete the pyrolysis process and obtain a preliminarily dense C / SiC composite material. S4. The preliminarily dense C / SiC composite material is impregnated under a nitrogen atmosphere at a pressure of 3 MPa. Then, the above step S3 is repeated with the same parameters to obtain a two-dimensional C / SiC composite material with a density of 1.22 g / cm³. 3 .
[0029] That is, Comparative Example 2 underwent a total of two curing (layer curing)-pyrolysis processes.
[0030] Performance testing: The silicon carbide ceramic powder particles obtained in Example 1 were observed using a scanning electron microscope, and the results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the silicon carbide ceramic powder particles are irregular polygonal or blocky, with an increased specific surface area.
[0031] The density and flexural strength (at room temperature) of the two-dimensional C / SiC composite materials obtained in Example 1, Comparative Example 1, and Comparative Example 2 were tested, and their three-point bending force-displacement curves are shown below. Figure 2 As shown, the specific values for density and average three-point bending strength (bending strength) at room temperature are given in Table 1. From... Figure 2 It can be seen that the two-dimensional C / SiC composite material prepared by the method in Example 1 has the best mechanical properties. Its curve shows the highest peak load and the largest area under the curve, indicating that it not only has excellent flexural strength but also absorbs more energy before fracture, resulting in optimal flexural strength.
[0032] Table 1. Results of density and mechanical property tests
[0033] As can be seen from Table 1, the preparation method provided by the present invention achieves densification of C / SiC within two rounds of curing and pyrolysis, and also significantly improves its mechanical properties.
[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for producing a short dense period two-dimensional C / SiC composite material, characterized in that, The method comprises the following steps: S1, mixing silicon carbide ceramic powder with water, ball milling, drying, and then placing in potassium hydroxide solution, alkali washing, to obtain alkali washed silicon carbide particles; S2, placing the alkali washed silicon carbide particles in a vinyl silane coupling agent solution, dispersing, heating the mixed solution, modifying, to obtain vinyl modified silicon carbide particles; S3, dissolving polycarbosilane, vinyl polycarbosilane and peroxide initiator in n-hexane, then adding vinyl modified silicon carbide particles to the mixed solution, stirring, and rotary evaporation to obtain a coating precursor; S4, using a slot coating method to combine the coating precursor and carbon fiber fabric into a prepreg; S5, stacking and curing the prepreg, pyrolyzing in vacuum or protective atmosphere to obtain a preliminary dense C / SiC composite material; S6, impregnating the preliminary dense C / SiC composite material, repeating the stacking and curing and pyrolyzing steps in S5 1-2 times to obtain a two-dimensional C / SiC composite material.
2. The method for preparing a short-dense periodic two-dimensional C / SiC composite material according to claim 1, characterized in that, In S1, the particle size of the silicon carbide ceramic powder is 5-25 µm, the mass ratio of the silicon carbide ceramic powder to water is 1:5-10, the rotation speed of the ball milling is 500-700 rpm, and the ball milling time is 10-15 h.
3. The method for preparing a short-dense periodic two-dimensional C / SiC composite material according to claim 1, characterized in that, In S1, the concentration of the potassium hydroxide solution is 0.5-1.5 mol / L, the alkali washing temperature is 40-50℃, the alkali washing time is 12-24 h, and the alkali washing process is accompanied by stirring at a stirring rate of 1200-2000 rpm.
4. The method for preparing a short-dense periodic two-dimensional C / SiC composite material according to claim 1, characterized in that, In S2, the vinyl silane coupling agent solution is an aqueous solution of a vinyl silane coupling agent, the vinyl silane coupling agent includes at least one of vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tri(2-methoxyethoxy)silane, and vinyl triisopropoxysilane, and the mass concentration of the vinyl silane coupling agent solution is 2%-5%. The modification reaction temperature is 40-60℃, the modification reaction time is 10-24 h, and the modification reaction process is accompanied by stirring at a stirring speed of 1200-2000 rpm.
5. The method for preparing a short-dense periodic two-dimensional C / SiC composite material according to claim 1, characterized in that, In S3, the vinyl polycarbosilane is in a liquid state with a viscosity of 30-100 cps, and the polycarbosilane is in a solid state; the mass ratio of the polycarbosilane to the vinyl polycarbosilane is 5:4-6.
6. The method of claim 1, wherein the short dense phase two-dimensional C / SiC composite material is prepared by the following steps of: In S3, the peroxide initiator includes dicumyl peroxide or benzoyl peroxide, the mass of the peroxide initiator is 0.5%-1% of the mass of the vinyl polycarbosilane, the volume of the vinyl modified silicon carbide particles accounts for 20%-40% of the total volume of the polycarbosilane and the vinyl polycarbosilane, the peak temperature of the rotary evaporation is 80-95℃, and the pressure of the rotary evaporation is 0.05-1 kPa.
7. The method for preparing a short-dense periodic two-dimensional C / SiC composite material according to claim 1, characterized in that, In S4, the carbon fiber fabric includes a 2D fabric of T300 carbon fiber or a 2D fabric of T700 carbon fiber; The 2D fabric of T300 carbon fiber is selected from a plain weave fabric of T300 carbon fiber, a twill weave fabric of T300 carbon fiber, or a satin weave fabric of T300 carbon fiber; and the 2D fabric of T700 carbon fiber is selected from a plain weave fabric of T700 carbon fiber, a twill weave fabric of T700 carbon fiber, or a satin weave fabric of T700 carbon fiber.
8. The method of claim 7, wherein the short dense phase cycle is characterized by, The lamination curing mode in S5 includes vacuum bag pressing, hot pressing tank or mould pressing; the lamination curing initiation temperature is 120-140℃, and the lamination curing peak temperature is 180-250℃; the pyrolysis atmosphere includes nitrogen or argon, and the pyrolysis peak temperature is 900-1400℃.
9. The method for preparing a short-dense periodic two-dimensional C / SiC composite material according to claim 1, characterized in that, The impregnation mode in S6 is pressure impregnation, and the pressure impregnation pressure is 3-5MPa.
10. The two-dimensional C / SiC composite material prepared by the method for preparing short dense period two-dimensional C / SiC composite material according to any one of claims 1-9.