A SiC f / SiC composite structural components and their preparation methods

Abstract

This invention provides a SiC f The method for preparing SiC composite structural components includes the following steps: S1: Cutting silicon carbide fiber cloth and laying it in a graphite mold to obtain a fiber preform of the structural component; S2: Placing the fiber preform of the structural component, locked with a graphite mold, into a deposition furnace to prepare an interface layer; S3: Placing the preform of the structural component with the interface layer into a SiC deposition furnace to deposit a portion of the SiC matrix, thus obtaining SiC. f / Porous blank of SiC structural parts; S4: Prepare a composite slurry of SiC particles and C particles, and introduce the slurry into SiC using a slurry injection process. f / SiC structural parts porous blanks to obtain SiC f / SiC (SiC) structural component porous blank; S5: for SiC f / SiC (SiC) structural parts porous preforms are densified by silicon infiltration to obtain SiC f / SiC composite material structural parts; in step S5, silicon infiltration is performed using silicon slurry, which is a uniformly mixed preparation of silicon powder, inert filler, binder, and solvent. The resulting SiC f SiC composite structural components have a smooth surface, no liquid silicon adhesion, and good mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of ceramic matrix composites, specifically to a SiC... f / SiC composite structural components and their preparation methods. Background Technology

[0002] In SiC f In the fabrication of SiC ceramic matrix composite structural components, silicon infiltration is often used for densification. Currently, the commonly used silicon infiltration methods mainly include the self-absorption method and the embedding method.

[0003] In the self-absorption silicon infiltration process, silicon powder does not directly contact the sample blank. Instead, a porous carbon core connects the sample blank to the silicon powder. During silicon infiltration, liquid silicon enters the blank through the porous carbon core, completing densification. The self-absorption silicon infiltration path is relatively long, and at high silicon infiltration temperatures, due to the low viscosity and strong capillary force of liquid silicon, complete densification can be achieved for large structural components. However, for SiC... f For silicon infiltration of SiC composite structural components, silicon carbide fibers are easily damaged at high temperatures. To protect the silicon carbide fibers from thermal damage, the silicon infiltration process temperature needs to be controlled as low as possible. However, at low temperatures, the high viscosity of liquid silicon shortens the silicon infiltration path, making it challenging for large-sized SiC composites. f / SiC composite structural components cannot guarantee complete silicon infiltration, thus affecting the overall performance of the structural components.

[0004] The silicon infiltration process for ceramic-based structural components involves embedding the sample blank in silicon powder. While this can effectively shorten the silicon infiltration path, the biggest problem with this method is that it can cause liquid silicon to adhere to the sample blank, increasing the machining difficulty of the sample.

[0005] In addition, in traditional silicon infiltration processes, SiC f In the blank of a SiC structural component, a carbon source is introduced through PIP or CVI processes, and then the sample is densified by silicon infiltration. During this process, liquid silicon reacts with the carbon source to generate SiC. This reaction is exothermic and will cause the internal temperature of the blank to rise by 200~300℃, thereby causing thermal damage to the fibers and reducing the performance of the structural component. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies, and one of its objectives is to provide SiC with a short silicon diffusion path, good silicon diffusion effect, low silicon diffusion temperature, and no significant exothermic reaction. f The preparation method of SiC composite structural components can not only improve the SiC... f The mechanical properties of SiC composite structural components are guaranteed, and the surface of the components after silicon infiltration treatment is smooth and free of liquid silicon adhesion.

[0007] Another object of the present invention is to provide SiC with a smooth surface and no liquid silicon adhesion. f / SiC composite structural components.

[0008] The technical solution adopted in this invention is as follows:

[0009] A SiC f The preparation method of SiC composite structural components includes the following steps:

[0010] S1: After cutting the silicon carbide fiber cloth to the specified size, lay it in the graphite mold, lock the graphite mold, and obtain the structural fiber preform;

[0011] S2: The structural fiber preform, which is locked with a graphite mold, is placed in a deposition furnace to prepare an interface layer on the surface of the structural fiber preform;

[0012] S3: The prefabricated structural component with the interface layer prepared is placed in a SiC deposition furnace to deposit a partial SiC substrate, thus preparing SiC. f / Porous blank for SiC structural components;

[0013] S4: Prepare a composite slurry of SiC particles and C particles, and introduce the slurry into the SiC using a slurry injection process. f / SiC structural parts porous blanks to obtain SiC f / SiC (SiC) structural component porous blank;

[0014] S5: For SiC f / SiC (SiC) structural parts porous preforms are densified by silicon infiltration to obtain SiC f / SiC composite material structural parts; wherein, the silicon infiltration in step S5 includes the following steps:

[0015] SS1 Silicone Slurry Preparation: Silicone powder, inert filler, binder, and solvent are mixed evenly to obtain the silicone slurry.

[0016] SS2 Silicon Paste Coating: SS1 silicon paste is uniformly coated onto SiC. f The surface of the porous blank of the SiC structural component is coated. After coating, the structural component blank is dried in an oven. The coating of silicon slurry is repeated until the weight gain of the structural component blank is ≥90wt%.

[0017] SS3 Silicon Infiltration: The structural blank coated with SS2 silicon slurry is placed in a graphite mold coated with a BN layer. The graphite mold is then placed in a silicon infiltration furnace for silicon infiltration. After silicon infiltration is completed, the residual silicon slurry on the surface is removed to obtain SiC. f / SiC composite material structural components.

[0018] The SiC provided by this invention fThe method for fabricating SiC composite structural components can achieve densification of the components at low temperatures, thereby improving the SiC... f The mechanical properties of SiC composite structural components are improved, and the silicon infiltration process using silicon slurry not only retains the advantage of short silicon infiltration path of traditional embedding methods, but also avoids residual silicon adhering to the surface of the structural components, reducing the amount of machining required. This enables the development of large-size and complex SiC composite components. f The densification treatment of SiC composite structural components can effectively shorten subsequent processing time and improve the performance of SiC. f The fabrication efficiency of SiC composite structural components.

[0019] In a preferred embodiment, the deposition furnace in step S2 is a CVI deposition furnace, the interface layer is either C or BN, and the thickness of the interface layer is 0.2~1μm, preferably 0.3~0.6μm, and more preferably 0.4~0.5μm.

[0020] The preferred solution is SiC in step S3. f The volume content of the SiC matrix in the porous blank of the SiC structural component is 20~30 vol%, preferably 24~26 vol.

[0021] The inventors discovered that by depositing a portion of the SiC matrix, the fibers and interface layer can be prevented from being eroded by liquid silicon during subsequent silicon infiltration, thereby improving the mechanical properties of the composite material. The amount of SiC matrix deposited is controlled to be... f The SiC (SiC) porous preform contains 20-30% of the total volume. If the SiC matrix content is too low, the protection effect on the fibers and interface layer will be poor. If the SiC matrix content is too high, the SiC will not be able to penetrate into the sample during the subsequent slurry pouring process, which will affect the uniformity of the slurry pouring.

[0022] In a preferred embodiment, the infusion process in S4 is carried out in a vacuum infusion apparatus. Specifically, the steps involve pouring a slurry containing SiC particles and C particles into the vacuum infusion apparatus, immersing the SiC particles... f A porous blank for SiC structural components is vacuum-filled to obtain SiC. f / SiC (SiC) porous preform.

[0023] In a preferred embodiment, the composite slurry in S4 is composed of SiC particles, C particles, a dispersant, and a solvent. The dispersant is at least one of polyacrylamide, sodium carboxymethyl cellulose, and ammonium citrate, and the solvent is at least one of water or alcohol.

[0024] In a preferred embodiment, the SiC particles in the composite slurry have a particle size of 0.1~10μm, preferably 0.5~2μm, and the C particles have a particle size of 50~500nm, preferably 50~200nm.

[0025] In a preferred embodiment, the total content of SiC particles and C particles in the composite slurry is 45-65 wt%, the content of dispersant is 0.1-1 wt%, and the remainder is solvent; in a further preferred embodiment, the total content of SiC particles and C particles in the composite slurry is 50-60 wt%, and even more preferably 53%-57 wt%.

[0026] In a preferred embodiment, the C particle content in the composite slurry is 1-4 wt% of the SiC particle mass, preferably 1.5-2.5 wt%.

[0027] Through extensive experiments, the inventors discovered that when the mass ratio of C particles to SiC particles in the composite slurry is controlled within the above-mentioned range, it can maintain relative stability with the silicon slurry during silicon infiltration. When the amount of SiC particles and C particles added to the composite slurry is too high, the exothermic reaction between Si and C will be more obvious, affecting the mechanical properties of the composite material. On the other hand, when the amount added is too low, the silicon infiltration of the composite material will be incomplete, affecting the mechanical properties of the composite material.

[0028] In a preferred embodiment, in step SS1, the mass fractions of silicon powder, inert filler, and binder in the silicon slurry are 35~45wt%, 5~15wt%, and 0.5~2wt%, respectively, with the remainder being solvent.

[0029] In a further preferred embodiment, the silicon slurry contains silicon powder, inert filler, and binder in weights of 38-42 wt%, 8-12 wt%, and 0.1-1.5 wt%, respectively, with the remainder being solvent.

[0030] In a preferred embodiment, the purity of the silicon powder is ≥99.9%, and the median particle size of the silicon powder is 20~60μm, more preferably 30~50μm.

[0031] In a preferred embodiment, the inert filler is at least one of silicon nitride powder, silicon carbide powder, aluminum nitride powder, boron nitride powder, and graphite powder.

[0032] In a preferred embodiment, the median particle size of the inert filler is 1~10μm, and more preferably 1~5μm.

[0033] The inventors discovered that when the median particle size of the silicon powder and the inert filler is within the above range, the effect of preventing liquid silicon from sticking is the best.

[0034] In a preferred embodiment, the adhesive is at least one selected from polyvinyl alcohol, polyvinyl butyral, sodium carboxymethyl cellulose, and polyvinylpyrrolidone.

[0035] In a preferred embodiment, the solvent is one of water and alcohol.

[0036] In a preferred embodiment, the silicon diffusion temperature in the SS3 silicon diffusion step is 1420℃~1450℃, preferably 1430℃~1440℃, and the silicon diffusion time is 10~40min, preferably 20~30min.

[0037] The present invention also provides a SiC f / SiC composite structural components are prepared by any of the above-mentioned preparation methods.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] (1) The SiC of the present invention f A method for preparing SiC composite structural components, through optimization of the preparation process, in

[0040] While lowering the silicon diffusion temperature of structural components, the silicon diffusion effect can be guaranteed, thereby improving the mechanical properties of composite material structural components.

[0041] (2) The preparation method provided by the present invention keeps the liquid silicon and carbon source relatively stable in the silicon infiltration process, which effectively overcomes the problem that the liquid silicon and carbon source react to generate SiC in the traditional silicon infiltration process, which causes significant heat release and leads to thermal damage to silicon carbide fibers.

[0042] (3) The method provided by the present invention changes the traditional silicon powder landfill process to a silicon slurry landfill process, which effectively avoids the problem of large-area adsorption of liquid molten silicon on the surface of structural parts. The present invention can realize that after silicon diffusion, liquid silicon and inert filler will form a loose shell on the sample surface, which effectively solves the problem of large areas of liquid silicon adhering in the silicon diffusion process of structural parts and reduces the machining cost of structural parts in subsequent processes.

[0043] (4) SiC prepared by the method of the present invention f / SiC composite structural components have a smooth surface and no liquid silicon adhesion, which can effectively reduce the machining difficulty in subsequent processes of structural components. Attached Figure Description

[0044] Figure 1 SiC f Preparation process flow of / SiC composite materials;

[0045] Figure 2 The SiC prepared in Example 1 f / SiC composite structural components;

[0046] Figure 3 SiC prepared for Comparative Example 2 f / SiC composite structural components.

[0047] In the figure, 1: the area after cleaning the loose shell layer on the sample surface of Example 1, 2: the loose shell layer formed on the sample surface after silicon infiltration in Example 1, and 3: the molten silicon adhering to the sample surface in Comparative Example 2. Detailed Implementation

[0048] The present invention will now be described in detail with reference to specific embodiments.

[0049] Example 1:

[0050] This embodiment focuses on the preparation of SiC. f / SiC composite structural components, such as Figure 1 The flowchart shown illustrates the preparation process following the steps outlined below:

[0051] 1. Prepare silicon carbide fiber cloth, cut it to a size of 210×210mm, lay the fiber cloth in the graphite mold, and use graphite bolts to lock the mold.

[0052] 2. The structural fiber preform, which is locked with a graphite mold, is placed in a BN deposition furnace to prepare a BN interface layer on the surface of the structural fiber preform. The interface layer thickness is about 500 nm.

[0053] 3. The prefabricated structural component with the prepared BN interface layer was placed in a SiC deposition furnace to deposit a partial SiC matrix with a density of 1.81 g / cm³. 3 Subsequently (with a SiC substrate volume of 27 vol%), SiC was prepared. f / Porous blank for SiC structural components;

[0054] 4. Weigh 55 parts by weight of a mixture of 1μm SiC particles and 100nm C particles, wherein the mass fraction of C particles is 0, 1, 2, 3, and 4 wt%, and they are numbered C0, C1, C2, C3, and C4. Weigh 0.5 parts by weight of polyacrylamide dispersant and the remaining parts by weight of deionized water. Mix the above materials evenly using a ball mill to obtain five slurries with different C particle contents. f The porous blank of SiC structural parts was divided into 5 equal parts and placed into a slurry injection device. Five different slurries with different C particle contents were poured into each part. After injection, five different SiC materials with different C particle contents were obtained. f / SiC (SiC) structural component porous blank;

[0055] 5. Weigh 40 parts by weight of silicon powder with a median particle size of 30 μm, weigh 10 parts by weight of aluminum nitride powder with a median particle size of 5 μm, weigh 1 part by weight of polyvinyl alcohol, and use the remaining parts by weight of deionized water as a solvent. Mix the four components evenly using a magnetic stirrer to obtain a silicon slurry. Coat the silicon slurry onto five SiC substrates with different C particle contents. f The surface of a porous SiC (SiC) structural blank was repeatedly dried and coated until the sample gained more than 90 wt% of weight. The coated sample was then placed in a graphite crucible coated with BN (Boron Nitrogen Nide) and placed in a silicon infiltration furnace for silicon infiltration. The silicon infiltration temperature was set at 1430℃ and the holding time was 30 min. After cooling, the silicon-infiltrated SiC was obtained. f / SiC composite structural component sample. For example... Figure 2 As shown, this is sample number C2. In the figure, the loose shell 2 formed on the sample surface after silicon infiltration and the area 1 after cleaning the loose shell on the sample surface show that there is no liquid silicon adhering.

[0056] After silica infiltration, five samples with different carbon particle contents were cut into five 10×10mm density and porosity test samples and five 60×9×3mm flexural strength samples. The density, porosity, and flexural strength of the samples were tested using standards GB / T 25995 and ASTM C1341-13. The test results of density, porosity, and flexural strength for samples with different numbers are shown in Table 1 below.

[0057] Table 1. Test results of density, porosity and flexural strength of samples with different carbon particle contents. Serial Number Sample number C particle percentage <![CDATA[Density (g / cm 3 ).]]> Porosity (%) Bending strength (MPa) Remark 1 C0 0wt% 2.60 4.6 463 2 C1 1wt% 2.72 2.5 534 3 C2 2wt% 2.74 2.3 528 4 C3 3wt% 2.75 1.9 514 5 C4 4wt% 2.73 2.4 475

[0058] Example 2: SiC was prepared using the following method f SiC composite structural components:

[0059] 1. Prepare silicon carbide fiber cloth, cut it to a size of 210×210mm, lay the fiber cloth in the graphite mold, and use graphite bolts to lock the mold.

[0060] 2. The fiber preform of the structural component, which is locked with a graphite mold, is placed in a BN deposition furnace to prepare a BN interface layer with a thickness of approximately 500 nm.

[0061] 3. The prefabricated structural component with the prepared BN interface layer was placed in a SiC deposition furnace to deposit a partial SiC matrix with a density of 1.81 g / cm³. 3 Subsequently (with a SiC substrate volume of 27 vol%), SiC was prepared. f / Porous blank for SiC structural components;

[0062] 4. Weigh 55 parts by weight of a mixture of 1μm SiC particles and 100nm C particles, wherein the C particles account for 2wt% by weight. Weigh 0.5 parts by weight of polyacrylamide dispersant and the remaining parts by weight of deionized water. Mix the above materials evenly using a ball mill to obtain a slurry for injection. Then, add the SiC... f The porous blank of the SiC structural component is placed into the slurry injection equipment, the slurry is poured in, and after the injection is completed, SiC is obtained. f / SiC (SiC) structural component porous blank;

[0063] 5. Weigh 40 parts by weight of silicon powder with a median particle size of 30 μm, weigh 10 parts by weight of aluminum nitride powder with a median particle size of 5 μm, weigh 1 part by weight of polyvinyl alcohol, and use the remaining parts by weight of deionized water as a solvent. Mix the four components evenly using a magnetic stirrer to obtain a silicon slurry. Then, add SiC... f The porous blank of SiC structural components is cut into three equal parts, numbered SGWD-1400, SGWD-1430, and SGWD-1460. Silicon slurry is then coated onto the SiC blanks with the different numbering. f The surface of a porous SiC (SiC) structural blank was repeatedly dried and coated until the sample gained more than 90 wt% of weight. The coated sample was then placed in a graphite crucible coated with BN (Boron Nitrogen Nide) and placed in a silicon infiltration furnace for silicon infiltration. The silicon infiltration temperatures were set at 1400℃, 1430℃, and 1460℃, with a holding time of 30 min. After cooling, silicon-infiltrated SiC was obtained. f / SiC composite structural component sample;

[0064] After silica infiltration, the three different numbered samples were cut into five 10×10mm density and porosity test samples and five 60×9×3mm flexural strength samples. The density, porosity, and flexural strength of the samples were tested using standards GB / T 25995 and ASTM C1341-13. The test results of density, porosity, and flexural strength for samples with different numbering are shown in Table 2 below.

[0065] Table 2. Test results of density, porosity, and flexural strength of samples at different silicating temperatures. Serial Number Sample number Silicon diffusion temperature <![CDATA[Density (g / cm 3 ).]]> Porosity (%) Bending strength (MPa) Remark 1 SGWD-1400 1400℃ 2.20 18.6 275 2 SGWD-1430 1430℃ 2.75 2.1 526 3 SGWD-1460 1460℃ 2.74 2.3 438

[0066] Example 3: SiC was prepared using the following method f SiC composite structural components:

[0067] 1. Prepare silicon carbide fiber cloth, cut it to a size of 210×210mm, lay the fiber cloth in the graphite mold, and use graphite bolts to lock the mold.

[0068] 2. The fiber preform of the structural component, which is locked with a graphite mold, is placed in a BN deposition furnace to prepare a BN interface layer with a thickness of approximately 500 nm.

[0069] 3. The prefabricated structural component with the prepared BN interface layer was placed in a SiC deposition furnace to deposit a partial SiC matrix with a density of 1.81 g / cm³. 3 Subsequently (with a SiC substrate volume of 27 vol%), SiC was prepared. f / Porous blank for SiC structural components;

[0070] 4. Weigh 55 parts by weight of a mixture of 1μm SiC particles and 100nm C particles, wherein the C particles account for 2wt% by weight. Weigh 0.5 parts by weight of polyacrylamide dispersant and the remaining parts by weight of deionized water. Mix the above materials evenly using a ball mill to obtain a slurry for injection. Then, add the SiC... f The porous blank of the SiC structural component is placed into the slurry injection equipment, the slurry is poured in, and after the injection is completed, SiC is obtained. f / SiC (SiC) structural component porous blank;

[0071] 5. Weigh 40 wt% of silicon powder with a median particle size of 30 μm. Weigh different mass fractions of aluminum nitride powder (4 wt%, 7 wt%, 10 wt%, 13 wt%, and 16 wt%) for experiments, numbered JL-TL-1, JL-TL-2, JL-TL-3, JL-TL-4, and JL-TL-5 respectively, with a median particle size of 5 μm. Weigh 1 wt% of polyvinyl alcohol and use the remaining mass fraction of deionized water as a solvent. Mix the four components evenly using a magnetic stirrer to obtain silicon slurry with different filler contents; then add SiC... f The porous blank of SiC structural parts was divided into 5 equal parts. The silicon slurry prepared above was used to coat the sample surface, and the coating was repeatedly dried until the sample weight gain reached more than 90 wt%. The coated sample was then placed in a graphite crucible coated with BN and placed in a silicon infiltration furnace for silicon infiltration. The silicon infiltration temperature was set at 1430℃, and the holding time was 30 min. After cooling, the silicon-infiltrated SiC was obtained. f / SiC composite structural component sample.

[0072] After silica infiltration, the sample surface was cleaned with a brush to check for any liquid silica adhering to the surface. The sample was then cut into five 10×10mm samples, and their density and porosity were tested using the standard GB / T 25995 "Test Methods for Density and Apparent Porosity of Fine Ceramics". The surface condition, density, and porosity test results of samples with different inert filler contents after silica infiltration are shown in Table 3 below.

[0073] Table 3. Surface condition, density, and porosity test results of slurry samples after silica infiltration with different inert filler contents. Serial Number Sample number Inert filler content Sample surface condition <![CDATA[Density (g / cm 3 ).]]> Porosity (%) Remark 1 JL-TL-1 4wt% Liquid silicon adhesion exists in some areas. 2.73 1.7 2 JL-TL-2 7wt% No liquid silicon adhesion 2.76 1.8 3 JL-TL-3 10wt% No liquid silicon adhesion 2.74 2.3 4 JL-TL-4 13wt% No liquid silicon adhesion 2.70 3.2 5 JL-TL-5 16wt% In a small area, liquid silicon adhesion is not present. 2.54 6.2

[0074] Example 4 SiC was prepared using the following method f SiC composite structural components:

[0075] 1. Prepare silicon carbide fiber cloth, cut it to a size of 210×210mm, lay the fiber cloth in the graphite mold, and use graphite bolts to lock the mold.

[0076] 2. The fiber preform of the structural component, which is locked with a graphite mold, is placed in a BN deposition furnace to prepare a BN interface layer with a thickness of approximately 500 nm.

[0077] 3. The prefabricated structural component with the prepared BN interface layer was placed in a SiC deposition furnace to deposit a partial SiC matrix with a density of 1.81 g / cm³. 3 Subsequently (with a SiC substrate volume of 27 vol%), SiC was prepared. f / Porous blank for SiC structural components;

[0078] 4. Weigh 55 parts by weight of a mixture of 1μm SiC particles and 100nm C particles, wherein the C particles account for 2wt% by weight. Weigh 0.5 parts by weight of polyacrylamide dispersant and the remaining parts by weight of deionized water. Mix the above materials evenly using a ball mill to obtain a slurry for injection. Then, add the SiC... f A porous SiC flat blank is placed into a slurry injection device, slurry is poured in, and after injection, SiC is obtained. f / SiC (SiC) structural component porous blank;

[0079] 5. Weigh 40 wt% of silicon powder and 10 wt% of aluminum nitride powder. Compare silicon powder and inert filler with different median particle sizes. The test numbers and the selected silicon powder and aluminum nitride powder particle sizes are shown in Table 4. Weigh 1 wt% of polyvinyl alcohol binder and use the remaining mass fraction of deionized water as a solvent. Mix the four components evenly using a magnetic stirrer to obtain a silicon slurry. Then, add SiC... fThe porous blank of SiC structural parts was divided into 12 equal parts. The silicon slurry prepared above was used to coat the sample surface, and the coating was repeatedly dried until the sample weight gain reached over 90 wt%. The coated sample was then placed in a graphite crucible coated with BN and placed in a silicon infiltration furnace for silicon infiltration. The silicon infiltration temperature was set at 1430℃, and the holding time was 30 min. After cooling, the silicon-infiltrated SiC was obtained. f / SiC composite structural component sample.

[0080] After silica infiltration, the sample surface was cleaned with a brush to check for any liquid silica adhering to the surface. Then, each sample was cut into five 10×10mm pieces. The density and porosity of the samples were tested using the standard GB / T 25995, "Test Methods for Density and Apparent Porosity of Fine Ceramics". The surface condition, density, and porosity test results of the silica-infiltrated samples with different median particle sizes are shown in Table 5.

[0081] Table 4. Particle size comparison test numbers and particle size information of silicon powder and aluminum nitride powder. Serial Number Test number Median particle size of silica powder (μm) Median particle size (μm) of aluminum nitride powder Remark 1 JL-LJ-1 10 0.5 2 JL-LJ-2 10 5 3 JL-LJ-3 10 15 4 JL-LJ-4 30 0.5 5 JL-LJ-5 30 5 6 JL-LJ-6 30 15 7 JL-LJ-7 50 0.5 8 JL-LJ-8 50 5 9 JL-LJ-9 50 15 10 JL-LJ-10 80 0.5 11 JL-LJ-11 80 5 12 JL-LJ-12 80 15

[0082] Table 5. Surface condition, density, and porosity test results of silica-infiltrated slurries with different median particle sizes. Serial Number Sample number Sample surface condition <![CDATA[Density (g / cm 3 ).]]> Porosity (%) Remark 1 JL-LJ-1 Liquid silicon adhesion exists in some areas. 2.73 1.7 2 JL-LJ-2 Liquid silicon adhesion exists in a small area. 2.67 3.8 3 JL-LJ-3 Liquid silicon adhesion exists in some areas. 2.59 5.8 4 JL-LJ-4 Liquid silicon adhesion exists in a small area. 2.74 2.3 5 JL-LJ-5 No liquid silicon adhesion 2.75 1.9 6 JL-LJ-6 Liquid silicon adhesion exists in a small area. 2.69 3.4 7 JL-LJ-7 Liquid silicon adhesion exists in a small area. 2.70 2.4 8 JL-LJ-8 No liquid silicon adhesion 2.74 2.2 9 JL-LJ-9 Liquid silicon adhesion exists in a small area. 2.68 3.5 10 JL-LJ-10 Liquid silicon adhesion exists in some areas. 2.73 1.9 11 JL-LJ-11 Liquid silicon adhesion exists in a small area. 2.72 2.5 12 JL-LJ-12 Liquid silicon adhesion exists in some areas. 2.65 3.6

[0083] Comparative Example 1 SiC was prepared using the following method f SiC composite structural components:

[0084] 1. Prepare silicon carbide fiber cloth, cut it to a size of 210×210mm, lay the fiber cloth in the graphite mold, and use graphite bolts to lock the mold.

[0085] 2. The structural fiber preform, which is locked with a graphite mold, is placed in a BN deposition furnace to prepare a BN interface layer on the surface of the structural fiber preform. The interface layer thickness is about 500 nm.

[0086] 3. The prefabricated structural component with the prepared BN interface layer was placed in a SiC deposition furnace to deposit a partial SiC matrix with a density of 1.81 g / cm³. 3 Subsequently (with a SiC substrate volume of 27 vol%), SiC was prepared. f / Porous blank for SiC structural components;

[0087] 4. A carbon source is introduced into the porous preform using a traditional PIP impregnation pyrolysis process. Specifically, the porous preform is impregnated with a phenolic resin alcohol solution, and then fully pyrolyzed at 1000℃. This impregnation pyrolysis process is repeated for 3 cycles to ensure that a sufficient amount of pyrolysis carbon source is introduced into the porous preform, thus obtaining SiC. f / SiC(C) flat structural porous blank;

[0088] 5. Weigh 40 parts by weight of silicon powder with a median particle size of 30 μm, weigh 10 parts by weight of aluminum nitride powder with a median particle size of 5 μm, weigh 1 part by weight of polyvinyl alcohol, and use the remaining parts by weight of deionized water as a solvent. Mix the four components evenly using a magnetic stirrer to obtain a silicon slurry. Coat the silicon slurry onto SiC. f The surface of the porous blank of the SiC (C) flat part is repeatedly dried and coated until the sample weight gain is more than 90 wt%. The coated sample is then placed in a graphite crucible coated with BN coating and placed in a silicon infiltration furnace for silicon infiltration. The silicon infiltration temperature is set at 1430℃ and the holding time is 30 min. After cooling, the silicon infiltrated sample is obtained.

[0089] After silica infiltration, the samples were cut into 10×10mm test samples and 60×9×3mm flexural strength samples. Density, porosity, and flexural strength were tested using standards GB / T 25995 and ASTM C1341-13. The test results showed a density of 2.44 g / cm³. 3 It has a porosity of 7.8% and a flexural strength of 376 MPa.

[0090] Comparing the experimental results of Example 1, it can be seen that the sample obtained by introducing a large amount of carbon source into the sample using the PIP process under low-temperature (1430℃) silicon infiltration conditions has lower density, higher porosity, and lower flexural strength. This is mainly because the large amount of carbon introduced into the sample of Example 1, during the silicon infiltration process, due to the low silicon infiltration temperature, high silicon viscosity, and weak capillary force, cannot quickly penetrate into the sample. The reaction of Si and C to form silicon carbide causes volume expansion, blocking the silicon infiltration channels, resulting in unreacted cracked carbon and unpenetrated areas in the sample. In addition, the reaction of Si and C releases a large amount of heat, damaging the fiber strength. In contrast, the Example 1, due to the addition of less C source, does not have the problems of blocked silicon infiltration channels and large amounts of exothermic reaction of silicon and carbon, thus exhibiting higher performance.

[0091] Comparative Example 2 SiC was prepared using the following method f SiC composite structural components:

[0092] 1. Prepare silicon carbide fiber cloth, cut it to a size of 210×210mm, lay the fiber cloth in the graphite mold, and use graphite bolts to lock the mold.

[0093] 2. The fiber preform of the structural component, which is locked with a graphite mold, is placed in a BN deposition furnace to prepare a BN interface layer with a thickness of approximately 500 nm.

[0094] 3. The prefabricated structural component with the prepared BN interface layer was placed in a SiC deposition furnace to deposit a partial SiC matrix with a density of 1.81 g / cm³. 3 Subsequently (with a SiC substrate volume of 27 vol%), SiC was prepared. f / Porous blank for SiC structural components;

[0095] 4. Weigh 55 parts by weight of a mixture of 1μm SiC particles and 100nm C particles, wherein the C particles account for 2wt% by weight. Weigh 0.5 parts by weight of polyacrylamide dispersant and the remaining parts by weight of deionized water. Mix the above materials evenly using a ball mill to obtain a slurry for injection. Then, add the SiC... f The porous blank of the SiC structural component is placed into the slurry injection equipment, the slurry is poured in, and after the injection is completed, SiC is obtained. f / SiC (SiC) structural component porous blank;

[0096] 5. SiC f A porous blank of a SiC (SiC) structural component is placed in a graphite crucible coated with BN. A layer of Si powder is poured onto the surface of the blank, with the same mass as the flat sample. The blank is then placed in a silicon infiltration furnace for silicon infiltration. The silicon infiltration temperature is set to 1430℃ and the holding time is 30 min. After cooling, the silicon-infiltrated sample is obtained.

[0097] The state of the sample after silicon infiltration is as follows Figure 3 As shown, a large amount of residual silicon is adsorbed on the sample surface, as seen in the molten silicon 3 adhering to the sample surface, which severely affects the sample surface condition. In contrast, the sample condition of Example 1, which used silicon slurry for silicon infiltration, is as follows: Figure 2 As shown, there is no residual silicon adhering, which greatly reduces the machining difficulty of the sample.

[0098] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A SiC f The preparation method of SiC composite structural components includes the following steps: S1: After cutting the silicon carbide fiber cloth to the specified size, lay it in the graphite mold, lock the graphite mold, and obtain the structural fiber preform; S2: The structural fiber preform, which is locked with a graphite mold, is placed in a deposition furnace to prepare an interface layer on the surface of the structural fiber preform; S3: The prefabricated structural component with the interface layer prepared is placed in a SiC deposition furnace to deposit a partial SiC substrate, thus preparing SiC. f / Porous blank for SiC structural components; S4: Prepare a composite slurry of SiC particles and C particles, and introduce the slurry into the SiC using a slurry injection process. f / SiC structural parts porous blanks to obtain SiC f / SiC (SiC) structural component porous blank; S5: For SiC f / SiC (SiC) structural parts porous preforms are densified by silicon infiltration to obtain SiC f / SiC composite material structural components; The silicon infiltration process in step S5 includes the following steps: SS1 Silicone Slurry Preparation: Silicone powder, inert filler, binder, and solvent are mixed evenly to obtain the silicone slurry. SS2 Silicon Paste Coating: SS1 silicon paste is uniformly coated onto SiC. f / SiC (SiC) structural parts porous blank surface, after coating, SiC f The porous blank of the SiC structural component is placed in an oven and dried. The coating of silicon slurry is repeated until the weight gain of the structural component blank is ≥90wt%. SS3 silicon infiltration: The structural blank coated with SS2 silicon slurry is placed in a graphite mold coated with a BN layer. The graphite mold is then placed in a silicon infiltration furnace for silicon infiltration treatment. After silicon infiltration is completed, the residual silicon slurry on the surface is removed to obtain SiC. f / SiC composite material structural components.

2. A SiC according to claim 1 f The method for preparing SiC composite structural components is characterized by, The deposition furnace in step S2 is a CVI deposition furnace, and the interface layer is either C or BN, with a thickness of 0.2~1μm. SiC in step S3 f The volume content of SiC matrix in the porous blank of SiC structural parts is 20~30 vol.

3. A SiC according to claim 1 f The method for preparing SiC composite structural components is characterized by, The infusion process described in S4 is carried out in a vacuum infusion apparatus, where a slurry containing SiC particles and C particles is poured into the vacuum infusion apparatus to immerse the SiC particles. f A porous SiC preform is vacuum-injected to obtain SiC. f / SiC (SiC) porous preform.

4. A SiC according to claim 1 f The method for preparing SiC composite structural components is characterized by, The composite slurry in S4 is composed of SiC particles, C particles, a dispersant and a solvent. The dispersant is at least one of polyacrylamide, sodium carboxymethyl cellulose and ammonium citrate, and the solvent is at least one of water or alcohol.

5. A SiC according to claim 1 f The method for preparing SiC composite structural components is characterized by, The composite The total content of SiC particles and C particles in the slurry is 45~65wt%, the content of dispersant is 0.1~1wt%, and the remainder is solvent; the particle size of SiC particles in the composite slurry is 0.1~10μm, and the particle size of C particles is 50~500nm.

6. A SiC according to claim 5 f The method for preparing SiC composite structural components is characterized by, The C particle content in the composite slurry is 1-4 wt% of the SiC particle mass.

7. A SiC according to claim 1 f The method for preparing SiC composite structural components is characterized by, In step SS1, the silicon slurry contains silicon powder, inert filler, and binder in proportions of 35-45 wt%, 5-15 wt%, and 0.5-2 wt%, respectively, with the remainder being solvent. The purity of the silicon powder is ≥99.9%, and the median particle size of the silicon powder is 20~60μm; The inert filler is at least one of silicon nitride powder, silicon carbide powder, aluminum nitride powder, boron nitride powder, and graphite powder; The median particle size of the inert filler is 1~10μm.

8. A SiC according to claim 7 f The method for preparing SiC composite structural components is characterized by, The adhesive is at least one of polyvinyl alcohol, polyvinyl butyral, sodium carboxymethyl cellulose, and polyvinylpyrrolidone. The solvent is either water or alcohol.

9. A SiC according to claim 1 f The method for preparing SiC composite structural components is characterized by, The silicon diffusion temperature in the SS3 silicon diffusion step is 1420℃~1450℃, and the silicon diffusion time is 10~40min.

10. A SiC f / SiC composite structural component, comprising a SiC composite material as described in any one of claims 1 to 9 f The SiC composite structural component was prepared by a specific method.

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