A silicon carbide fiber reinforced silicon carbide composite material with an in-situ grown nanowire interface layer and a preparation method and application thereof

Abstract

This invention belongs to the field of silicon carbide composite material technology, and relates to a silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer, its preparation method, and its application. This invention discloses a method for obtaining a silicon carbide fiber cloth with a SiC nanowire interface layer through electroplating and in-situ growth on a silicon carbide fiber cloth loaded with a pyrolytic carbon interface layer. The silicon carbide fiber-reinforced silicon carbide composite material prepared using this SiC nanowire interface layer exhibits good performance.

Description

Technical Field

[0001] This invention belongs to the field of silicon carbide composite material technology, and relates to a silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer, its preparation method and application. Background Technology

[0002] Silicon carbide fiber reinforced silicon carbide (SiC) f SiC composites possess unique physical and chemical properties, such as low density, corrosion resistance, radiation resistance, and excellent high-temperature resistance. These properties endow SiC with... f The stability and durability of SiC composite materials in extreme environments make them promising for wide application in high-tech fields such as hypersonic aircraft, aero engines, and nuclear reactors.

[0003] Compared to high-temperature alloys, SiC f SiC composites still exhibit significant shortcomings in mechanical properties such as fracture strength and fracture toughness, which has become a prominent bottleneck restricting their wider application. Improving the overall mechanical properties of composites, especially their toughness and crack resistance, has become one of the core research issues in this field. Existing research mainly focuses on reinforcing fiber properties, optimizing interfacial layer structure characteristics, and improving preparation and heat treatment processes. However, utilizing novel nanoreinforcing materials such as nanoparticles, nanofibers, or nanowires to improve the mechanical properties of SiC composites remains a significant challenge. f Exploration of the toughness of SiC composites is relatively limited. Nanoreinforcement, as a second-phase strengthening unit, can form an effective load transfer and crack deflection mechanism within the matrix microregions, thereby achieving simultaneous strengthening and toughening at the microscopic level. In particular, introducing SiC nanowires into the matrix between fiber layers and fiber bundles can significantly extend the crack propagation path, increase crack propagation energy consumption, and improve the microscopic brittleness of the matrix, thus significantly enhancing the overall fracture toughness and structural reliability of the composite material.

[0004] Currently, in SiC fThe main technical approaches for introducing nano-reinforcing agents into SiC composites include electrophoretic deposition and in-situ growth. In traditional electrophoretic deposition, SiC fiber woven fabric is typically used as the working electrode, and a metal plate as the counter electrode, both immersed in an electrophoretic solution containing nanowires. Under an applied electric field, the nano-reinforcing agents suspended in the liquid migrate towards the working electrode due to surface charging, eventually adsorbing and depositing on the fiber surface to form an interface layer. Because this method directly connects the deposition matrix to the electrode, it is more suitable for depositing on highly conductive matrices. However, SiC fibers themselves have high resistance, and electrophoretic deposition on their surface easily leads to uneven electric field distribution, making it difficult to achieve a uniform distribution of the nano-reinforcing phase. Furthermore, the nanowires used in this method are pre-synthesized, and their size and morphology are difficult to adapt to the complex pore structure inside the composite material. Therefore, the nanowires often cannot fully penetrate and uniformly disperse within the fiber bundle. The nanowires introduced through electrophoretic deposition mainly rely on physical adsorption and electrostatic interactions for bonding with the fiber surface, resulting in weak interfacial bonding strength. Under load, debonding easily occurs, severely limiting the reinforcing efficiency.

[0005] Chinese patent application document (publication number: CN108218457B) discloses a method for improving the electrophoretic deposition process of nano-reinforcement by using a metal plate as an auxiliary electrode and fixing SiC fiber woven fabric on the electrode to form a working electrode, thereby preparing a more uniform nanowire interface layer. However, this method cannot control the nanowire content.

[0006] Chinese patent application document (publication number: CN119263859A) discloses a method of loading a metal catalyst precursor onto a PyC interface layer via vacuum impregnation, followed by in-situ generation of a SiC nanowire interface layer on the surface of the PyC interface layer using chemical vapor deposition. This method cannot effectively control the content and distribution of the catalyst, resulting in an uneven distribution of the nanowire interface layer.

[0007] Chinese patent application document (publication number: CN113735604A) discloses a method of immersing a composite material preform in a cobalt acetate solution, introducing a cobalt catalyst using an ultrasonic process, and then directly preparing a SiC nanowire interface layer via chemical vapor infiltration after ultrasonication. This method still suffers from problems such as the inability to effectively control the catalyst content and uneven nanowire distribution; furthermore, the chemical vapor infiltration process used in this method requires sophisticated equipment, has a long preparation cycle, and is costly. Summary of the Invention

[0008] The purpose of this invention is to address the aforementioned problems in the prior art by proposing a method for obtaining a silicon carbide fiber cloth with a SiC nanowire interface layer through electroplating and in-situ growth on a silicon carbide fiber cloth loaded with a cracked carbon interface layer. The silicon carbide fiber reinforced silicon carbide composite material made from this silicon carbide fiber cloth with a SiC nanowire interface layer has better performance.

[0009] One objective of this invention is achieved through the following technical solution: A method for preparing a silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer includes the following steps: (1) A silicon carbide fiber cloth loaded with a cracked carbon interface layer and two metal sheets were placed together in an electroplating solution for electroplating to obtain a silicon carbide fiber cloth loaded with a catalyst, wherein the catalyst loaded on its surface is nickel nanoparticles and the catalyst loading amount is 0.4~3wt%; The electroplating solution contains nickel sulfate at a concentration of 220-250 g / L, nickel chloride at a concentration of 30-45 g / L, sulfuric acid at a concentration of 1-2 g / L, boric acid at a concentration of 25-35 g / L, and a pH of 3.5-4.5. (2) The mixture of catalyst-supported silicon carbide fiber cloth, liquid polycarbosilane, and carbon source is placed together in an argon atmosphere and heated to a first temperature of 1200-1400℃ at a rate of 1-10℃ / min and held for 1-12h to obtain silicon carbide fiber cloth with SiC nanowire interface layer; wherein the loading amount of SiC nanowire interface layer is 10-25wt%; (3) Silicon carbide fibers loaded with SiC nanowire interface layers were arranged in liquid polycarbosilane and subjected to pressure impregnation, followed by a first pyrolysis to obtain porous SiC nanowires. f / SiC composite material preform; (4) Porous SiC f The / SiC composite preform was impregnated under pressure in liquid polycarbosilane, followed by a second pyrolysis to obtain a silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer.

[0010] Preferably, in step (1), the metal sheet is a nickel sheet.

[0011] Preferably, in step (1), the distance between the anode and the cathode is 60~80mm.

[0012] Further optimization is achieved by setting the distance between the anode and the cathode to 75 mm.

[0013] Preferably, in step (1), the electroplating current is 0.1A and the electroplating time is 2~5min.

[0014] Further optimization, in step (1), in the electroplating solution, the silicon carbide fiber cloth loaded with the cracked carbon interface layer is used as the cathode, and the two metal nickel sheets are used as the anodes respectively. The distance between the anode and the cathode is 75 mm. Electroplating is carried out at a current of 0.1 A for 2~5 min to obtain the silicon carbide fiber cloth loaded with catalyst.

[0015] Preferably, in step (1), the average melting point of the catalyst is 1000~1200℃.

[0016] Further preferred, in step (1), the catalyst is nickel nanoparticles with an average melting point of 1200℃.

[0017] Preferably, in step (1), the method for preparing the silicon carbide fiber cloth loaded with the cracked carbon interface layer includes: depositing the silicon carbide fiber cloth in an environment with acetylene and methane as carbon source gases and argon as protective gas, the deposition temperature is 900~1000℃, the deposition time is 4~6h, and the silicon carbide fiber cloth loaded with the cracked carbon interface layer is obtained, the loading amount of the cracked carbon interface layer is 10~25wt%.

[0018] Further optimization involves using acetylene at a flow rate of 25–50 mL / min, methane at a flow rate of 37.5–75 mL / min, and argon at a flow rate of 100–200 mL / min.

[0019] Further preferred, the loading of the cracked carbon interface layer in the silicon carbide fiber cloth loaded with the cracked carbon interface layer is 10~25wt%.

[0020] Preferably, in step (2), the carbon source in the mixture includes at least one of carbon black, phenolic resin and activated carbon.

[0021] Preferably, in step (2), the mass ratio of liquid polycarbosilane to carbon source in the mixture is (0.1~1):1.

[0022] Further preferred, in step (2), the mass ratio of liquid polycarbosilane to carbon source in the mixture is (0.4~0.7):1.

[0023] More preferably, in step (2), the mass ratio of liquid polycarbosilane to carbon source in the mixture is 0.5:1.

[0024] Preferably, in step (2), the mass ratio of the silicon carbide fiber cloth supporting the catalyst to the mixture is (0.03~0.05):1.

[0025] Preferably, in step (2), the heating rate of the first temperature is 5~10℃ / min.

[0026] Preferably, in step (2), the aspect ratio of the SiC nanowires in the SiC nanowire interface layer is (100~500):1.

[0027] Preferably, the average melting point of the catalyst in step (1) is less than or equal to the first temperature in step (2).

[0028] Further preferred, the average melting point of the catalyst in step (1) is less than the first temperature in step (2).

[0029] Preferably, in steps (3, 4), the pressure impregnation is carried out under nitrogen gas at a pressure of 1~5 MPa for 1~6 hours.

[0030] Further optimization involves the following steps (3 and 4): pressure impregnation is carried out under nitrogen atmosphere at a pressure of 1-3 MPa for 1-3 hours.

[0031] Preferably, in step (3), the silicon carbide fiber cloth is obtained after pressure impregnation, and the impregnation amount is 5~20wt%.

[0032] Preferably, in step (3), the first pyrolysis includes: stacking and fixing 1 to 30 pieces of impregnated silicon carbide fiber cloth in a mold, heating it to a second temperature of 500 to 700°C at a heating rate of 0.5 to 3°C / min, and holding it at that temperature for 0.5 to 5 hours.

[0033] Further preferred, in step (3), the first pyrolysis includes: placing 1 to 30 pieces of impregnated silicon carbide fiber cloth in a metal mold and applying a pressure of 1 to 5 MPa for stacking and fixing, keeping it for 1 to 6 hours, placing the stacked and fixed mold in an argon environment, heating it to a second temperature of 500 to 700°C at a heating rate of 0.5 to 3°C / min and keeping it at that temperature for 0.5 to 5 hours.

[0034] Preferably, in step (4), the second pyrolysis includes: heating to a third temperature of 1000-1300℃ at a heating rate of 0.5-5℃ / min and holding at that temperature for 0.5-5h.

[0035] Further preferred, in step (4), the second pyrolysis includes: heating to a third temperature of 1100~1250℃ at a heating rate of 1~3℃ / min and holding at that temperature for 0.5~2h.

[0036] Preferably, the second temperature < the third temperature ≤ the first temperature.

[0037] Further preferred, the second temperature < the average melting point of the catalyst ≤ the third temperature < the first temperature.

[0038] Preferably, in step (4), the pressure impregnation and the second pyrolysis are repeated 0 to 20 times.

[0039] The second objective of this invention is achieved through the following technical solution: A silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer is prepared by the above-described method.

[0040] Preferably, the bulk density of the silicon carbide fiber-reinforced silicon carbide composite material with the in-situ grown nanowire interface layer is ≥2.46 g / cm³. 3 Open pores ≤3.2%.

[0041] Further preferably, the bulk density of the silicon carbide fiber-reinforced silicon carbide composite material with the in-situ grown nanowire interface layer is 2.47~2.52 g / cm³. 3 The number of open pores is 2.5~3.2%.

[0042] Preferably, the silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer has a flexural strength ≥460 MPa and a fracture toughness ≥10 MPa•m. 1 / 2 .

[0043] Further preferably, the silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer has a flexural strength ≥ 560 MPa and a fracture toughness ≥ 13.5 MPa•m. 1 / 2 .

[0044] The third objective of this invention is achieved through the following technical solution: Application of a silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer in the fields of hypersonic aircraft and nuclear reactor cladding materials.

[0045] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention obtains a SiC nanowire interface layer on the surface of silicon carbide fiber cloth loaded with a cracked carbon interface layer through electroplating and in-situ growth steps. The introduction of the SiC nanowire interface can significantly extend the crack propagation path of silicon carbide fiber reinforced silicon carbide composite material, improve the brittleness of the micro-matrix, and thus effectively enhance the bending strength and fracture toughness.

[0046] 2. This invention controls the current, time, and distance between the anode and cathode during the electroplating process, and uniformly distributes a certain amount of catalyst particles on the surface of the silicon carbide fiber cloth substrate loaded with the cracked carbon interface layer, ensuring that SiC nanowires are formed in the subsequent in-situ growth of SiC nanowires without corroding the silicon carbide fiber cloth substrate.

[0047] 3. In the electroplating solution used in this invention, nickel sulfate and nickel chloride are used as the main salts, sulfuric acid is used to adjust the pH of the electroplating solution, and boric acid is used as an acid-base buffer to balance the pH of the solution. If the pH is too low, the polarization effect will be weakened, the electroplated metal catalyst particles will be coarse, resulting in uneven growth of nanowires. If the pH is too high, the catalyst layer will become loose and brittle, the bonding force between the catalyst and the substrate will be reduced, resulting in a weakening of the bonding force between the nanowire interface layer and the substrate, and ultimately reducing the toughening effect of the nanowires.

[0048] 4. In the in-situ growth of SiC nanowires, the present invention controls the temperature, holding time and heating rate of the heat treatment; the first temperature of forming the SiC nanowire interface layer in step (2) is higher than the melting point of the catalyst particles generated in step (1). If the first temperature is too low, the SiC nanowires cannot grow; if the first temperature is too high, it will cause thermal damage to the silicon carbide fiber cloth substrate; if the holding time of the first temperature is too short, the liquid polycarbosilane will not be completely decomposed, resulting in a decrease in the total amount and aspect ratio of SiC nanowires; if the heating rate is too slow, the liquid polycarbosilane will decompose prematurely before the melting point of the catalyst is reached, affecting the growth of SiC nanowires.

[0049] 5. This invention uses precursor pyrolysis chemical vapor deposition to replace the traditional chemical vapor infiltration method, which greatly reduces the equipment requirements for in-situ growth of SiC nanowires, thereby reducing production costs. The preparation method has good applicability.

[0050] 6. This invention uses an impregnation pyrolysis method to improve the density of the composite material. The lower molding pressure and densification temperature greatly preserve the structure of the SiC nanowire interface layer, successfully improving the strength and toughness of the composite material. This is of great significance for the development of hypersonic aircraft, nuclear reactor cladding materials and other fields. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the electroplating step in the preparation method of silicon carbide fiber-reinforced silicon carbide composite material with in-situ grown nanowire interface layer of the present invention. Figure 2 This is a surface SEM image of the silicon carbide fiber cloth with a SiC nanowire interface layer in Example 1 of the present invention. Figure 3 This is a SEM image of another surface of the silicon carbide fiber cloth with a SiC nanowire interface layer in Example 1 of the present invention. Figure 4 This is a cross-sectional SEM image of the silicon carbide fiber cloth with SiC nanowire interface layer loaded in Example 1 of the present invention; Figure 5 This is a surface SEM image of the silicon carbide fiber cloth of the SiC nanowire interface layer in Example 2 of the present invention; Figure 6This is a surface SEM image of the silicon carbide fiber cloth with a SiC nanowire interface layer in Example 2 of the present invention. Figure 7 This is a cross-sectional SEM image of the silicon carbide fiber cloth with SiC nanowire interface layer loaded in Example 2 of the present invention; Figure 8 This is a TEM image of the SiC nanowires in the silicon carbide fiber cloth with the SiC nanowire interface layer in Example 1 of the present invention. Detailed Implementation

[0052] The technical solution of the present invention will be further described and illustrated below through specific embodiments. It should be understood that the specific embodiments described herein are only for the purpose of helping to understand the present invention and are not intended to limit the present invention.

[0053] Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used in the art, and the methods used in the embodiments are all conventional methods in the art.

[0054] In this article, the raw materials and equipment include: Silicon carbide fiber cloth, Fujian Liya New Materials Co., Ltd.; Liquid polycarbosilane (LPCS), ceramicization yield greater than 70%, Fujian Liya New Materials Co., Ltd. Activated carbon, Shanghai Aladdin Biochemical Technology Co., Ltd.; The electroplating equipment uses a single-channel DC power supply.

[0055] The tests in this article include: Archimedes' method of water displacement was used to test the open porosity and bulk density. The bending strength test method adopts the three-point bending test method; The fracture toughness was tested using the single-sided notched beam method.

[0056] This paper describes a method for preparing silicon carbide fiber-reinforced silicon carbide composites with in-situ grown nanowire interface layers, comprising the following steps: (1) Silicon carbide fiber cloth was deposited in an environment with acetylene and methane as carbon source gases and argon as protective gas. The deposition temperature was 900~1000℃ and the deposition time was 4~6h to obtain silicon carbide fiber cloth loaded with a cracked carbon interface layer. The flow rate of acetylene was 25~50 mL / min, the flow rate of methane was 37.5~75 mL / min, and the flow rate of argon was 100~200 mL / min. The loading amount of cracked carbon interface layer was 10~25wt%. Nickel sulfate, nickel chloride, sulfuric acid, and boric acid are added to water and stirred in a water bath at 50-80°C for 10-120 minutes to obtain an electroplating solution. The electroplating solution has a nickel sulfate concentration of 220-250 g / L, a nickel chloride concentration of 30-45 g / L, a sulfuric acid concentration of 1-2 g / L, a boric acid concentration of 25-35 g / L, and a pH of 3.5-4.5. In the above electroplating solution, silicon carbide fiber cloth loaded with a cracked carbon interface layer is used as the cathode, and two nickel sheets are used as the anodes respectively. The distance between the anode and the cathode is 75 mm. Electroplating is carried out at a current of 0.1 A for 2 to 5 minutes, and then the cloth is taken out and dried to obtain silicon carbide fiber cloth loaded with catalyst. The catalyst loading is 0.4 to 3 wt%, and the catalyst is iron nanoparticles or nickel nanoparticles. (2) Liquid polycarbosilane and activated carbon are mixed in a mass ratio of (0.1~1):1 to obtain a mixture; the silicon carbide fiber cloth with catalyst is placed together with the mixture in a graphite crucible, and heated to a first temperature of 1200~1400℃ at a heating rate of 1~10℃ / min in a flowing argon atmosphere and held for 1~6h to obtain silicon carbide fiber cloth with SiC nanowire interface layer; wherein the loading amount of SiC nanowire interface layer is 10~25wt%; The first temperature is greater than or equal to the melting point of the catalyst; (3) The silicon carbide fiber cloth loaded with SiC nanowire interface layer was immersed in liquid polycarbosilane and impregnated under nitrogen atmosphere at 1-5 MPa for 1-6 h to obtain impregnated silicon carbide fiber cloth; 20 pieces of impregnated silicon carbide fiber cloth were placed in a metal mold and stacked and fixed under pressure of 1-5 MPa, and then pyrolyzed in argon atmosphere, heated to a second temperature of 500-700℃ at a heating rate of 0.5-3℃ / min and held for 0.5-5 h to obtain porous SiC. f / SiC composite material preform; (4) Porous SiC f The SiC composite preform is immersed in liquid polycarbosilane and impregnated under nitrogen atmosphere at 1-5 MPa for 1-6 hours to obtain the impregnated preform; then it is placed in argon atmosphere and heated to a third temperature of 1000-1300℃ at a heating rate of 0.5-5℃ / min and held for 0.5-5 hours to obtain the composite intermediate. (5) Repeat step (4) 0 to 20 times to obtain silicon carbide fiber reinforced silicon carbide composite material with in-situ grown nanowire interface layer.

[0057] In this paper, the preparation method of silicon carbide fiber cloth loaded with cracked carbon interface layer includes: placing silicon carbide fiber cloth (50×60mm, 1g) in a closed environment, continuously introducing argon gas at 200mL / min, acetylene at 50mL / min, and methane at 75mL / min, heating to 1000℃, and holding at 6min to obtain silicon carbide fiber cloth loaded with cracked carbon interface layer; wherein the loading amount of cracked carbon interface layer in the silicon carbide fiber cloth loaded with cracked carbon interface layer is 15wt%.

[0058] In this paper, the loading materials and their amounts are closely related in each step. Excessive pyrolytic carbon interfacial layer can affect stress transmission in the composite material, reducing its strength; insufficient loading may cause the catalyst to directly erode the fibers, also reducing the composite material's strength and toughness. Insufficient catalyst leads to uneven nanowire growth, while excessive catalyst forms large catalyst particles during nanowire growth, also affecting the uniformity of the nanowire interfacial layer. The amount of liquid polycarbosilane added affects the loading of the SiC nanowire interfacial layer; excessive SiC nanowire interfacial layer results in more closed pores, reducing the compactness of the composite material and thus reducing its strength, while insufficient SiC nanowire interfacial layer makes it difficult to exert its reinforcing and toughening effects.

[0059] In this paper, a schematic diagram of the electroplating step in the preparation method of the silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer of the present invention is shown below. Figure 1 .

[0060] Example 1 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material with in-situ grown nanowire interface layer in this embodiment includes the following steps: (1) Add nickel sulfate, nickel chloride, sulfuric acid and boric acid to water, heat in a water bath to 60°C, and mechanically stir for 60 min to obtain an electroplating solution; the concentration of nickel sulfate in the electroplating solution is 250 g / L, the concentration of nickel chloride is 45 g / L, the concentration of sulfuric acid is 2 g / L, the concentration of boric acid is 35 g / L, and the pH is 3.5. In the electroplating solution, a silicon carbide fiber cloth loaded with a cracked carbon interface layer is fixed with a clamp and connected to the negative terminal of the power supply as a cathode. Two metal nickel sheets are connected to the positive terminal of the power supply as anodes. The distance between the anode and the cathode is 75 mm. Electroplating is carried out at a current of 0.1 A for 2 min. After removal and drying, a catalyst-loaded silicon carbide fiber cloth is obtained. The mass of the catalyst is 0.52 wt% of the silicon carbide fiber cloth loaded with the cracked carbon interface layer, that is, the catalyst loading is 0.52 wt%. The catalyst is nickel nanoparticles with an average melting point of 1200℃.

[0061] (2) Mix 12.5g of liquid polycarbosilane with 25g of activated carbon powder to obtain a mixture; place the silicon carbide fiber cloth loaded with catalyst in step (1) together with the mixture in a graphite crucible, and heat it to the first temperature of 1300℃ at a heating rate of 10℃ / min in a flowing argon environment and keep it at that temperature for 3h to obtain a silicon carbide fiber cloth loaded with SiC nanowire interface layer, wherein the mass of the SiC nanowire interface layer is 15.4wt% of the silicon carbide fiber cloth loaded with cracked carbon interface layer, that is, the loading amount of SiC nanowire interface layer is 15.4wt%.

[0062] (3) The silicon carbide fiber cloth loaded with SiC nanowire interface layer in step (2) is immersed in liquid polycarbosilane and impregnated under pressure in a nitrogen environment, wherein the impregnation pressure is 2MPa and the impregnation holding time is 2h, to obtain the impregnated silicon carbide fiber cloth; 20 pieces of impregnated silicon carbide fiber cloth are placed in a metal mold and stacked and fixed under a pressure of 2MPa; the stacked and fixed mold is placed in an argon environment for the first pyrolysis, and the temperature is raised to the second temperature of 600℃ at a heating rate of 2℃ / min and held for 1h to obtain porous SiC f / SiC composite preform.

[0063] (4) The porous SiC from step (3) f The SiC composite preform was immersed in liquid polycarbosilane and impregnated under pressure in a nitrogen environment. The impregnation pressure was 2 MPa and the impregnation holding time was 2 h to obtain the impregnated preform. Then, it was placed in an argon environment for a second pyrolysis, and the temperature was raised to a third temperature of 1200℃ at a heating rate of 2℃ / min and held for 1 h to obtain the composite intermediate. (5) Repeat step (4) 10 times to obtain silicon carbide fiber reinforced silicon carbide composite material with in-situ grown nanowire interface layer.

[0064] The properties of the silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer prepared in this embodiment are shown in Table 1.

[0065] Example 2

[0066] The preparation method of silicon carbide fiber-reinforced silicon carbide composite material with in-situ grown nanowire interface layer in this embodiment includes the following steps: (1) The process is carried out according to step (1) of Example 1, except that the electroplating time is 5 min, and a silicon carbide fiber cloth loaded with catalyst is obtained. (2~5) Proceed according to steps (2~5) of Example 1.

[0067] The properties of the silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer prepared in this embodiment are shown in Table 1.

[0068] Example 3

[0069] The preparation method of silicon carbide fiber-reinforced silicon carbide composite material with in-situ grown nanowire interface layer in this embodiment includes the following steps: (1) Proceed according to step (1) of Example 1; (2) Follow the steps of Example 1 (2), except that 15g of liquid polycarbosilane is mixed with 25g of activated carbon powder; this step yields silicon carbide fiber cloth loaded with SiC nanowire interface layer, wherein the mass of SiC nanowire interface layer is 18.6wt% of silicon carbide fiber cloth loaded with cracked carbon interface layer.

[0070] (3~5) Proceed according to steps (3~5) of Example 1.

[0071] The properties of the silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer prepared in this embodiment are shown in Table 1.

[0072] Comparative Example 1 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material in this comparative example includes the following steps: (1) Follow the steps (3) of Example 1, except that the silicon carbide fiber cloth without cracked carbon interface layer is immersed in liquid polycarbosilane; (2~3) Proceed according to steps (4~5) of Example 1.

[0073] The properties of the silicon carbide fiber-reinforced silicon carbide composite material prepared in this comparative example are shown in Table 1.

[0074] Comparative Example 2 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material in this comparative example includes the following steps: (1) Follow the steps (3) of Example 1, except that the silicon carbide fiber cloth loaded with the cracked carbon interface layer in step (1) of Example 1 is immersed in liquid polycarbosilane; (2~3) Proceed according to steps (4~5) of Example 1.

[0075] The properties of the silicon carbide fiber-reinforced silicon carbide composite material prepared in this comparative example are shown in Table 1.

[0076] Comparative Example 3 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material in this comparative example includes the following steps: (1) Follow the steps (3) of Example 1, except that the silicon carbide fiber cloth loaded with catalyst in step (2) of Example 1 is immersed in liquid polycarbosilane; (2~5) Proceed according to steps (4~5) of Example 1.

[0077] The properties of the silicon carbide fiber-reinforced silicon carbide composite material prepared in this comparative example are shown in Table 1.

[0078] Comparative Example 4 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material in this comparative example includes the following steps: (1) Add ferrous chloride and boric acid to water, heat in a water bath to 45°C, and mechanically stir for 60 min to obtain the second electroplating solution; the concentration of ferrous chloride in the second electroplating solution is 55 g / L, the concentration of boric acid is 35 g / L, and the pH is 3.7.

[0079] In this electroplating solution, a silicon carbide fiber cloth loaded with a cracked carbon interface layer is fixed with a clamp and connected to the negative terminal of a power supply as a cathode, and two metal iron sheets are connected to the positive terminal of a power supply as anodes. The distance between the anode and the cathode is 75 mm. Electroplating is performed at a current of 0.1 A for 2 minutes, and the cloth is then removed and dried to obtain a silicon carbide fiber cloth loaded with a catalyst. The catalyst is iron nanoparticles with an average melting point of 1000 °C. (2~5) Proceed according to steps (2~5) of Example 1.

[0080] The properties of the silicon carbide fiber-reinforced silicon carbide composite material prepared in this comparative example are shown in Table 1.

[0081] Comparative Example 5 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material in this comparative example includes the following steps: (1) Add nickel sulfate, nickel chloride, sulfuric acid, and boric acid to water, heat in a water bath to 60°C, and mechanically stir for 60 min to obtain the first electroplating solution; the concentration of nickel sulfate in the electroplating solution is 250 g / L, the concentration of nickel chloride is 45 g / L, the concentration of sulfuric acid is 2 g / L, the concentration of boric acid is 35 g / L, and the pH is 3.5; in the first electroplating solution, fix the silicon carbide fiber cloth loaded with the cracked carbon interface layer with a clamp and connect it to the negative terminal of the power supply as the cathode, and connect two metal nickel sheets to the positive terminal of the power supply as the anode. The distance between the anode and the cathode is 75 mm. Electroplating is carried out at a current of 0.1 A for 1 min, and then the cloth is taken out and dried to obtain the silicon carbide fiber cloth loaded with the catalyst; the catalyst is nickel nanoparticles; Ferrous chloride and boric acid were added to water, heated in a water bath to 45°C, and mechanically stirred for 60 minutes to obtain an electroplating solution. The second electroplating solution contained 55 g / L ferrous chloride, 35 g / L boric acid, and had a pH of 3.7. The first electroplating solution was replaced with the second electroplating solution, and the two nickel sheets were replaced with two iron sheets. Electroplating was performed at 0.1 A for 1 minute, and the solution was removed and dried to obtain a silicon carbide fiber cloth loaded with a catalyst. The catalyst consisted of nickel nanoparticles and iron nanoparticles with an average melting point of 1100°C. (2~5) Proceed according to steps (2~5) of Example 1.

[0082] The properties of the silicon carbide fiber-reinforced silicon carbide composite material prepared in this comparative example are shown in Table 1.

[0083] Comparative Example 6 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material in this comparative example includes the following steps: (1) Follow the steps (1) of Example 1, except that the distance between the anode and the cathode is 50 mm; (2~5) Proceed according to steps (2~5) of Example 1.

[0084] The properties of the silicon carbide fiber-reinforced silicon carbide composite material prepared in this comparative example are shown in Table 1.

[0085] Comparative Example 7 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material in this comparative example includes the following steps: (1) Follow the steps (1) of Example 1, except that the concentration of nickel sulfate in the electroplating solution is 250 g / L, the concentration of nickel chloride is 45 g / L, the concentration of sulfuric acid is 1 g / L, the concentration of boric acid is 35 g / L, and the pH is 5. (2~5) Proceed according to steps (2~5) of Example 1.

[0086] The properties of the silicon carbide fiber-reinforced silicon carbide composite material prepared in this comparative example are shown in Table 1.

[0087] Comparative Example 8 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material in this comparative example includes the following steps: (1~2) Proceed according to steps (1~2) of Example 1; (3) Follow the steps (3) of Example 1, except that the silicon carbide fiber cloth loaded with catalyst and the mixture are placed together in a graphite crucible, heated to 1100°C at a heating rate of 10°C / min and kept at that temperature for 3 hours in a flowing argon environment to obtain silicon carbide fiber cloth loaded with SiC nanowire interface layer. (4~5) Proceed according to steps (4~5) of Example 1.

[0088] The properties of the silicon carbide fiber-reinforced silicon carbide composite material prepared in this comparative example are shown in Table 1.

[0089] Comparative Example 9 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material in this comparative example includes the following steps: (1) Mix 5g of nickel powder, 2g of polyvinyl butyral (PVB), and 200ml of ethanol to obtain a mixed solution. Immerse the silicon carbide fiber cloth loaded with the cracked carbon interface layer in the mixed solution and sonicate for 1h. Remove and dry to obtain the silicon carbide fiber cloth loaded with catalyst. The catalyst is nickel nanoparticles with a loading of 0.50wt%. (2~5) Proceed according to steps (2~5) of Example 1.

[0090] The properties of the silicon carbide fiber-reinforced silicon carbide composite material prepared in this comparative example are shown in Table 1.

[0091] Comparative Example 10 The preparation method of silicon carbide fiber-reinforced silicon carbide composite material in this comparative example includes the following steps: (1) Follow the steps (1) of Example 1, except that a silicon carbide fiber cloth without cracked carbon interface layer is fixed with a clamp and connected to the negative terminal of the power supply as a cathode. (2~5) Proceed according to steps (2~5) of Example 1.

[0092] The properties of the silicon carbide fiber-reinforced silicon carbide composite material prepared in this comparative example are shown in Table 1.

[0093] Table 1. Performance of Silicon Carbide Fiber Reinforced Silicon Carbide Composites

[0094] according to Figures 2-8 As shown in Table 1, the present invention forms catalyst particles on the surface of silicon carbide fibers loaded with a cracked carbon interface layer by electroplating, and then grows a SiC nanowire interface layer in situ to obtain silicon carbide fiber cloth loaded with a SiC nanowire interface layer. The silicon carbide fiber reinforced silicon carbide composite material made based on the silicon carbide fiber cloth loaded with a SiC nanowire interface layer has good performance.

[0095] in Figure 2 The surface of the silicon carbide fiber cloth with the SiC nanowire interface layer obtained in Example 1 is uniformly distributed with catalyst particles. Figure 3 and Figure 4 The silicon carbide fiber cloth with SiC nanowire interface layer obtained in Example 1 shows that SiC nanowires are uniformly distributed on the surface of silicon carbide fibers and grow around the interface of silicon carbide fibers, which proves that the bonding force between SiC nanowires and silicon carbide fibers is good, which is conducive to exerting the reinforcing and toughening effect of SiC nanowires as interface layer. Figure 5 The silicon carbide fiber cloth with the SiC nanowire interface layer obtained in Example 2 also shows a uniform distribution of catalyst particles on its surface, and its catalyst loading is greater than that in Example 1; according to Figure 6It is known that a portion of the surface of the silicon carbide fiber cloth with the SiC nanowire interface layer obtained in Example 2 was corroded; with increased catalyst content, it is easier to melt and form large particles at high temperatures, and excessive local catalyst content may erode the silicon carbide fibers. According to Figure 7 As can be seen from the cross-sectional diagram, the lower half of the silicon carbide fiber has begun to be eroded by the catalyst, resulting in changes in the morphology and contrast of the silicon carbide fiber. The overall strength and toughness of the composite material obtained after the silicon carbide fiber is eroded will decrease.

[0096] Figure 8 The TEM image shows SiC nanowires in the interface layer of SiC nanowires. Catalyst particles are present at the top of the SiC nanowires, proving that the growth mechanism of the nanowires is a gas-liquid-solid growth mechanism. The catalyst plays a key role in the growth process of the nanowires, and the nanowires are uniformly distributed along the length direction.

[0097] In summary, this invention obtains a SiC nanowire interface layer on the surface of silicon carbide fiber cloth loaded with a cracked carbon interface layer through electroplating and in-situ growth steps. The introduction of the SiC nanowire interface can significantly extend the crack propagation path of silicon carbide fiber-reinforced silicon carbide composite material, improve the brittleness of the micro-matrix, and thus effectively enhance the bending strength and fracture toughness.

[0098] All aspects, embodiments, and features of this invention should be considered illustrative in all respects and not limiting of the invention; the scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0099] In the preparation method of this invention, the order of the steps is not limited to the listed order. For those skilled in the art, variations in the order of the steps without creative effort are also within the scope of protection of this invention. Furthermore, two or more steps or actions can be performed simultaneously.

[0100] Finally, it should be noted that the specific embodiments described herein are merely illustrative examples of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A method for preparing a silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer, characterized in that, The preparation method includes the following steps: (1) A silicon carbide fiber cloth loaded with a cracked carbon interface layer and two metal sheets were placed together in an electroplating solution for electroplating to obtain a silicon carbide fiber cloth loaded with a catalyst, wherein the catalyst loaded on its surface is nickel nanoparticles and the catalyst loading amount is 0.4~3wt%; The electroplating solution contains nickel sulfate at a concentration of 220-250 g / L, nickel chloride at a concentration of 30-45 g / L, sulfuric acid at a concentration of 1-2 g / L, boric acid at a concentration of 25-35 g / L, and a pH of 3.5-4.

5. (2) In an argon atmosphere, the mixture of catalyst-supported silicon carbide fiber cloth, liquid polycarbosilane, and carbon source is heated to a first temperature of 1200-1400℃ at a rate of 1-10℃ / min and held for 1-12h to obtain silicon carbide fiber cloth with a SiC nanowire interface layer; wherein the loading amount of the SiC nanowire interface layer is 10-25wt%; (3) Silicon carbide fibers loaded with SiC nanowire interface layers were arranged in liquid polycarbosilane and subjected to pressure impregnation, followed by a first pyrolysis to obtain porous SiC nanowires. f / SiC composite material preform; (4) Porous SiC f The / SiC composite preform was impregnated under pressure in liquid polycarbosilane, followed by a second pyrolysis to obtain a silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer.

2. The method for preparing silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer according to claim 1, characterized in that, In step (1), the distance between the anode and the cathode is 60~80mm; the electroplating current is 0.1A and the electroplating time is 2~5min.

3. The method for preparing silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer according to claim 1, characterized in that, In step (1), the method for preparing the silicon carbide fiber cloth loaded with the cracked carbon interface layer includes: depositing the silicon carbide fiber cloth in an environment with acetylene and methane as carbon source gases and argon as protective gas, the deposition temperature is 900~1000℃, the deposition time is 4~6h, and the silicon carbide fiber cloth loaded with the cracked carbon interface layer is obtained, the loading amount of the cracked carbon interface layer is 10~25wt%.

4. The method for preparing silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer according to claim 1, characterized in that, In step (2), the mass ratio of liquid polycarbosilane to carbon source in the mixture is (0.1~1):1, and the mass ratio of silicon carbide fiber cloth supporting catalyst to mixture is (0.03~0.05):

1.

5. The method for preparing silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer according to claim 1, characterized in that, In step (3), the first pyrolysis includes: stacking and fixing 1 to 30 pieces of impregnated silicon carbide fiber cloth in a mold, heating it to a second temperature of 500 to 700°C at a heating rate of 0.5 to 3°C / min, and holding it at that temperature for 0.5 to 5 hours.

6. The method for preparing silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer according to claim 1, characterized in that, In step (4), the second pyrolysis includes: heating to a third temperature of 1000-1300℃ at a heating rate of 0.5-5℃ / min and holding at that temperature for 0.5-5h.

7. The method for preparing silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer according to claim 5 or 6, characterized in that, Second temperature < average melting point of catalyst ≤ third temperature < first temperature.

8. A silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer, characterized in that, It is prepared by the method described in any one of claims 1 to 7 for the preparation of silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer.

9. The silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer according to claim 8, characterized in that, The bulk density of the silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer is ≥2.46 g / cm³. 3 Porosity ≤ 3.2%; flexural strength ≥ 460 MPa; fracture toughness ≥ 10 MPa•m 1 / 2 .

10. The application of a silicon carbide fiber-reinforced silicon carbide composite material with an in-situ grown nanowire interface layer as described in any one of claims 8 to 9 in the fields of hypersonic aircraft and nuclear reactor cladding materials.

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