A silicon carbide fiber-reinforced silicon carbide ceramic matrix composite material with BN / SiC / Y2Si2O7 multilayer interface and its preparation method

Abstract

This invention relates to a silicon carbide fiber-reinforced silicon carbide ceramic matrix composite material with a BN / SiC / Y2Si2O7 multilayer interface and its preparation method. The preparation method includes: (1) depositing a BN interface on the surface of silicon carbide fibers to obtain SiC. f / BN preform; (2) in the obtained SiC f / BN preform surface SiC interface deposited to obtain SiC f / BN / SiC preform; (3) using sol-gel, impregnation-pulling and high-temperature pyrolysis in the obtained SiC f A Y2Si2O7 interface layer was prepared on the surface of the / BN / SiC preform to obtain SiC. f / BN / SiC / Y2Si2O7 preform; (4) the obtained SiC f The SiC matrix was densified using a BN / SiC / Y2Si2O7 preform to obtain SiC with a BN / SiC / Y2Si2O7 multilayer interface. f / SiC ceramic matrix composites.

Description

Technical Field

[0001] This invention belongs to the field of ceramic matrix composite technology, specifically relating to a SiC composite with a BN / SiC / Y2Si2O7 multilayer interface. f / SiC ceramic matrix composites and their preparation methods. Background Technology

[0002] Due to the unique service environment of aero engines, they face harsh conditions such as thermal-water-oxygen coupling corrosion caused by complex environments including high-temperature and high-pressure combustion gases, corrosion from calcium, magnesium, aluminum, and silicates encountered during flight, and scouring by high-speed combustion gases. These conditions place higher demands on aero engine materials. Currently, high-temperature alloy materials still exhibit temperature gaps at turbine inlets. SiCf / SiC composite materials, with their excellent high-temperature resistance, high specific modulus, high specific strength, low density, good oxidation resistance, and low coefficient of thermal expansion, have become one of the important candidate materials for the hot-section components of next-generation aero engines.

[0003] SiC f SiC ceramic matrix composites consist of SiC fibers, interfaces, and a SiC matrix. Previous research has primarily focused on modifying the SiC matrix to improve its high-temperature resistance to water and oxygen corrosion, thereby protecting the fibers. The interface, as a component of SiC... f SiC composites are a crucial component, not only transferring loads and deflecting cracks but also protecting the fibers. However, the interfaces of composite materials used in the hot-end components of aero-engines are mostly boron-nitrogen (BN) interfaces. Under high-temperature water-oxygen coupling environments, BN interfaces react to form a glassy B₂O₃ phase, which can help close cracks. However, this glassy B₂O₃ is further corroded by high-temperature steam, generating volatile substances such as boric acid and metaboric acid. Therefore, designing antioxidant interfaces for composite materials to improve their antioxidant properties and enhance their environmental tolerance is a key challenge for SiC used in aero-engines. f Issues that must be closely monitored during the research and development of SiC ceramic matrix composites. Chinese Patent 1 (Publication No. CN110894164A) discloses a silicon carbide ceramic matrix composite material with rare earth silicate layered distribution and its preparation method. This method uses slurry impregnation and chemical vapor infiltration to distribute at least two layers of rare earth silicate in a ring shape within the matrix, effectively hindering the erosion of the matrix and fiber bundles by oxygen and water vapor, thus improving the material's resistance to water and oxygen. However, the ring-shaped rare earth silicate distribution introduced in this invention, located within the matrix between fiber bundles, cannot improve the crack deflection ability at the mechanical interface of the composite material, thus failing to achieve toughening and reinforcement of the material's mechanical properties. Summary of the Invention

[0004] For SiC fTo address the problems of poor water and oxygen resistance and insufficient crack deflection ability in SiC ceramic matrix composites, this invention provides a SiC composite with a BN / SiC / Y2Si2O7 multilayer interface. f / SiC ceramic matrix composites and their preparation methods.

[0005] In a first aspect, the present invention provides a SiC with a BN / SiC / Y2Si2O7 multilayer interface. f Methods for preparing SiC ceramic matrix composites include:

[0006] (1) A BN interface layer is deposited on the surface of silicon carbide fiber to prepare SiC. f / BN prefabricated body;

[0007] (2) In the obtained SiC f A SiC interface layer is deposited on the surface of the BN preform to obtain SiC f / BN / SiC preform;

[0008] (3) Sol-gel, dip-coating and high-temperature pyrolysis were used to obtain SiC f A Y2Si2O7 interface layer was prepared on the surface of the / BN / SiC preform to obtain SiC. f / BN / SiC / Y2Si2O7 preform;

[0009] (4) The obtained SiC f The SiC matrix was densified using a BN / SiC / Y2Si2O7 preform to obtain SiC with a BN / SiC / Y2Si2O7 multilayer interface. f / SiC ceramic matrix composites.

[0010] Preferably, the silicon carbide fiber is a one-dimensional silicon carbide fiber bundle, a two-dimensional silicon carbide fiber cloth, a three-dimensional silicon carbide fiber braid, or a hybrid structure thereof.

[0011] Preferably, the BN interface layer is prepared by chemical vapor deposition (CVD), wherein the precursor of the BN interface layer includes a nitrogen source and a boron source; the nitrogen source is at least one selected from ammonia, urea, ammonium chloride, and ammonium borate; the boron source is at least one selected from boron trichloride, diborane, borane, boric acid, and ammonium borate; the molar ratio of the nitrogen source to the boron source is (0.2–5):1; the parameters of the CVD include: hydrogen as the carrier gas, a deposition temperature of 500–2000℃, a deposition pressure of 0.1 kPa–12 GPa; and the thickness of the BN interface is 100–1000 nm.

[0012] Preferably, the SiC interface layer is prepared by chemical vapor deposition (CVD), wherein the precursor of the SiC interface layer is at least one selected from methyltrichlorosilane, propane and silane, propane and trichlorosilane, and hexamethyldisilane; the parameters of the CVD method include: hydrogen as the carrier gas, a precursor-to-hydrogen content ratio of 1:(2-10), a deposition temperature of 600-1800℃, and a deposition pressure of 0.1-30 kPa; and the thickness of the SiC interface layer is 0.2-5 μm.

[0013] Preferably, the Y2Si2O7 interface layer is prepared by sol-gel, dip-coating and high-temperature pyrolysis, comprising:

[0014] (a) Dissolve the precursor of the Y2Si2O7 interface layer in a solvent, and then add a catalyst to form a precursor solution;

[0015] (b) The obtained precursor solution was heated and stirred in a water bath and then aged at room temperature. After aging and stabilization, the precursor solution was coated onto SiC by dip-coating. f The surface of the / BN / SiC preform is finally dried and pyrolyzed at high temperature.

[0016] (c) Repeat step (b) of dip-dipping and high-temperature pyrolysis 1–20 times to obtain SiC. f / BN / SiC / Y2Si2O7 preform.

[0017] Preferably, the precursor of the Y2Si2O7 interface layer includes a silicon source and a yttrium source; the silicon source is at least one of tetraethyl orthosilicate, sodium silicate, polydimethylsiloxane, and hexamethyldisiloxane; the yttrium source is at least one of yttrium nitrate hexahydrate, yttrium chloride, yttrium acetate, and yttrium isopropoxide; and the molar ratio of the silicon source to the yttrium source is (0.2-4):1.

[0018] Preferably, the solvent is at least one selected from anhydrous ethanol, acetone, butanol, ethyl acetate, water, and xylene; the catalyst is at least one selected from hydrochloric acid, nitric acid, citric acid, acetic acid, sodium hydroxide, and ammonia; the mass ratio of catalyst concentration in the precursor solution is 0.01–20 vol%; and the molar ratio of silicon source to yttrium source concentration in the precursor solution is 1:(1–200).

[0019] Preferably, the temperature of the water bath heating and stirring is room temperature to 100°C, and the heating time is 1 to 120 hours; the aging time is 2 to 200 hours.

[0020] Preferably, the parameters of the immersion-lifting method are: immersion speed of 0.1 to 1000 μm / s, immersion time of 0.1 to 72 hours; lifting speed of 0.1 to 1000 μm / s, and standing time of 0.1 to 100 hours.

[0021] Preferably, the drying temperature is 60–180°C and the time is 2–24 hours; the high-temperature pyrolysis temperature is 600–1700°C and the time is 0.5–10 hours, the heating rate is 0.1–10°C / min, and the atmosphere is argon or nitrogen; the thickness of the Y2Si2O7 interface layer is 100–1000 nm.

[0022] Preferably, the SiC substrate is densified by chemical vapor deposition, wherein the precursor for SiC substrate densification is at least one of methyltrichlorosilane, propane and silane, propane and trichlorosilane, and hexamethyldisilane; the parameters of the chemical vapor deposition method include: hydrogen as carrier gas, deposition temperature of 600-1800℃, and deposition pressure of 0.1-30kPa.

[0023] Secondly, the present invention also provides a SiC with a BN / SiC / Y2Si2O7 multilayer interface prepared by the above preparation method. f / SiC ceramic matrix composites.

[0024] In this invention, SiC with a BN / SiC / Y2Si2O7 multilayer interface is used. f / SiC ceramic matrix composites, due to the advantages of Y2Si2O7 such as low water vapor volatilization rate, low oxygen diffusivity, thermochemical properties and thermal expansion coefficient matching SiC, and high chemical compatibility, can achieve toughening mechanisms such as multilayer crack deflection when applied to the interface of composite materials, and delay the oxidation damage of the inner BN interface, thereby improving the oxidation resistance of the composite material interface.

[0025] Beneficial effects:

[0026] This invention prepares a SiC with a BN / SiC / Y2Si2O7 multilayer interface using chemical vapor deposition, sol-gel method, and dip-coating method. f / SiC ceramic matrix composites can not only control the growth of the Y2Si2O7 interface layer by adjusting the sol properties and impregnation parameters, but also enhance the ability of the interface to deflect cracks, effectively improve the toughness of the material, and endow the material interface with excellent oxidation resistance. Attached Figure Description

[0027] Figure 1 To prepare SiC with a BN / SiC / Y2Si2O7 multilayer interface, this invention is used. f Process route for SiC ceramic matrix composites; Figure 2 Micrograph of the composite material prepared in Example 1; Figure 3 The tensile test curve of the composite material prepared in Example 1; Figure 4The tensile fracture morphology of the composite material prepared in Example 1; Figure 5 The tensile test curve of the composite material prepared in Example 2; Figure 6 The tensile test curve of the composite material prepared in Example 3; Figure 7 Tensile test curves of the composite material prepared in Example 4; Figure 8 Tensile test curves for the composite material prepared in Comparative Example 1; Figure 9 The tensile fracture morphology of the composite material prepared in Comparative Example 1 is shown. Figure 10 Tensile test curves for the composite material prepared in Comparative Example 2; Figure 11 The tensile fracture morphology of the composite material prepared in Comparative Example 3 is shown. Figure 12 Tensile test curves for the composite material prepared in Comparative Example 3; Figure 13 The tensile fracture morphology of the composite material prepared in Comparative Example 4 is shown. Figure 14 Tensile test curves for the composite material prepared in Comparative Example 4. Detailed Implementation

[0028] To further illustrate the invention's content, features, and practical effects, the invention will be described in detail below with reference to embodiments. It should be noted that the modification methods of the invention are not limited to these specific implementation methods. Equivalent substitutions and modifications made by those skilled in the art based on their reading of the invention's content, without departing from the spirit and essence of the invention, are also within the scope of protection claimed by this invention.

[0029] The following exemplarily illustrates the SiC with a BN / SiC / Y2Si2O7 multilayer interface provided by the present invention. f Preparation methods of SiC ceramic matrix composites (e.g.) Figure 1 (As shown).

[0030] A BN interface was prepared on the surface of silicon carbide fibers using chemical vapor deposition to obtain SiC. f / BN prefabricated body.

[0031] In optional embodiments, the silicon carbide fiber may be a one-dimensional silicon carbide fiber bundle, a two-dimensional silicon carbide fiber cloth, a three-dimensional silicon carbide fiber braid, or a hybrid structure thereof. The precursor of the BN interface layer includes a nitrogen source and a boron source. The nitrogen source may be at least one selected from ammonia, urea, ammonium chloride, and ammonium borate. The boron source may be at least one selected from boron trichloride, diborane, borane, boric acid, and ammonium borate. The molar ratio of the nitrogen source to the boron source may be (0.2–5):1. The parameters of the chemical vapor deposition method include: hydrogen as the carrier gas, a deposition temperature of 500–2000℃ for the BN interface layer, a deposition pressure of 0.1 kPa–12 GPa, and a thickness of 100–1000 nm for the BN interface layer.

[0032] In SiC f A SiC interface layer was prepared on the surface of the / BN preform using chemical vapor deposition to obtain SiC f / BN / SiC preform.

[0033] In an optional embodiment, the precursor of the SiC interface layer may be at least one of methyltrichlorosilane, propane and silane, propane and trichlorosilane, and hexamethyldisilane. The parameters of the chemical vapor deposition method include: hydrogen as the carrier gas, a precursor-to-hydrogen content ratio of 1:(2-10), a deposition temperature of 600-1800℃, a deposition pressure of 0.1-30 kPa, and a SiC interface layer thickness of 0.2-5 μm.

[0034] In SiC f A Y2Si2O7 interface layer was prepared on the surface of the / BN / SiC preform using the sol-gel method, dip-coating, and high-temperature pyrolysis to obtain SiC. f / BN / SiC / Y2Si2O7 preform.

[0035] (a) Dissolve the precursor of the Y2Si2O7 interface layer in a solvent and add a catalyst to form a precursor solution.

[0036] (b) The precursor solution obtained in step (a) is heated and stirred evenly in a water bath, then aged at room temperature. After stabilization, it is dip-coating applied to the SiC substrate to coat the precursor solution. f / BN / SiC preform surface; after the impregnated preform is dried, it is subjected to high-temperature pyrolysis.

[0037] (c) Repeat the impregnation and pyrolysis process in step (b) 1 to 20 times to obtain SiC. f / BN / SiC / Y2Si2O7 preform.

[0038] In an optional embodiment, the precursor of the Y2Si2O7 interface layer includes a silicon source and a yttrium source. The silicon source may be at least one selected from tetraethyl orthosilicate, sodium silicate, polydimethylsiloxane, and hexamethyldisiloxane. The yttrium source may be at least one selected from yttrium nitrate hexahydrate, yttrium chloride, yttrium acetate, and yttrium isopropoxide. The molar ratio of the silicon source to the yttrium source may be (0.2–4):1.

[0039] The solvent may be at least one selected from anhydrous ethanol, acetone, butanol, ethyl acetate, water, and xylene. The catalyst may be at least one selected from hydrochloric acid, nitric acid, citric acid, acetic acid, sodium hydroxide, and ammonia. The mass ratio of the catalyst concentration in the precursor solution may be 0.01–20 wt%. The molar ratio of the silicon source to the yttrium source in the precursor solution may be 1:(1–200).

[0040] The water bath heating and stirring temperature is room temperature to 100℃, and the heating time is 1 to 120 hours; the aging time is 2 to 200 hours. The water bath heating and aging treatment affect the uniformity of the precursor sol. The lower the water bath temperature, the longer the required aging time, and the better the sol uniformity.

[0041] The parameters for the impregnation-coating method are as follows: impregnation speed of 0.1–1000 μm / s, impregnation time of 0.1–72 hours; and coating speed of 0.1–1000 μm / s, with a settling time of 0.1–200 hours. Excessive impregnation speed can easily generate air bubbles between fiber bundles, affecting the wettability of the material. Excessive coating speed can easily cause the sol to agglomerate between fiber bundles, affecting the interfacial properties of Y2Si2O7.

[0042] The drying temperature is 60–180°C, and the time is 2–24 hours. The high-temperature pyrolysis temperature can be 200–2000°C, and the time can be 0.5–10 hours. The heating rate is 0.1–10°C / min, and the atmosphere is argon or nitrogen. The thickness of the Y2Si2O7 interface layer is 100–1000 nm.

[0043] SiC matrix densification using chemical vapor deposition yields SiC with a BN / SiC / Y2Si2O7 multilayer interface. f / SiC ceramic matrix composites.

[0044] In an optional embodiment, the precursor for SiC matrix densification may be at least one of methyltrichlorosilane, propane and silane, propane and trichlorosilane, and hexamethyldisilane. The parameters of the chemical vapor deposition method include: hydrogen as the carrier gas, a deposition temperature of 600–1800°C, and a deposition pressure of 0.1–30 kPa.

[0045] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0046] Example 1

[0047] (1) A BN interface layer was prepared on a one-dimensional silicon carbide fiber bundle by chemical vapor deposition: ammonia was used as the nitrogen source, boron trichloride was used as the boron source, the molar ratio of nitrogen source to boron source was 1:1, hydrogen was used as the carrier gas, and a BN interface layer was deposited on the surface of silicon carbide fiber at a deposition temperature of 800℃ and a deposition pressure of 1 kPa. The resulting SiC f The thickness of the BN interface layer in the BN preform is 550 nm.

[0048] (2) Preparation of SiC interface layer by chemical vapor deposition: Methyltrichlorosilane was used as the precursor, hydrogen was used as the carrier gas, and the content ratio of precursor to hydrogen was 1:10. The SiC obtained in step (1) f A SiC interface layer was deposited on the surface of the / BN preform at a deposition temperature of 1000℃ and a deposition pressure of 5kPa. f The thickness of the SiC interface layer in the / BN / SiC preform is 600 nm.

[0049] (3) Preparation of Y2Si2O7 interface layer by sol-gel method and dip-coating method:

[0050] (a) In the sol-gel method, tetraethyl orthosilicate is used as the silicon source and yttrium nitrate hexahydrate is used as the yttrium source. The molar ratio of silicon source to yttrium source is 1:1. Tetraethyl orthosilicate and yttrium nitrate hexahydrate are dissolved in ethanol, and hydrochloric acid is added for catalysis (the concentration of hydrochloric acid is 36%). The pH of the solution is adjusted to <1 to obtain the precursor solution.

[0051] (b) The precursor solution obtained in step (a) was heated in a water bath at 60°C for 6 hours, stirred evenly, and then aged at room temperature for 24 hours. After stabilization, it was impregnated and pulled at a speed of 100 μm / s for 1 hour and a pulling speed of 100 μm / s for 24 hours. The impregnated preform was dried at 120°C for 24 hours and then subjected to high-temperature pyrolysis under an argon atmosphere at a temperature of 1400°C, a heating rate of 5°C / min, and a holding time of 2 hours.

[0052] (c) Repeat the impregnation and pyrolysis process in step (b) three times to obtain SiC. fThe thickness of the Y2Si2O7 interface layer in the / BN / SiC / Y2Si2O7 preform is approximately 200 nm.

[0053] (4) Densification of SiC substrate by chemical vapor deposition: Methyltrichlorosilane was used as a precursor and hydrogen as a carrier gas to densify the SiC substrate. The deposition temperature was 1000℃ and the deposition pressure was 0.1~30kPa, thus obtaining SiC with a BN / SiC / Y2Si2O7 multilayer interface. f / SiC composite material, its microstructure is as follows Figure 2 As shown.

[0054] The obtained composite material was subjected to single-filament tensile testing, and the tensile curve is as follows: Figure 3 As shown in the figure, the fracture strength is 170 N, and the fracture displacement of the material is 0.472 mm; the fracture morphology is as follows. Figure 4 As shown in the figure, the crack deflects along the Y2Si2O7 interface and can maintain the fiber pull-out performance, effectively releasing fracture energy and enhancing the toughness of the material.

[0055] Example 2

[0056] In this embodiment 2, SiC has a multilayer interface of BN / SiC / Y2Si2O7. f The preparation process of the SiC ceramic matrix composite material is the same as in Example 1, except that the pyrolysis temperature in step (b) is 1100℃, and the obtained SiC... f The thickness of the Y2Si2O7 interface layer in the / BN / SiC / Y2Si2O7 preform is approximately 230 nm.

[0057] The obtained composite material was subjected to single-filament tensile testing, and the tensile curve is as follows: Figure 5 As shown, the fracture strength is 177 N and the fracture displacement is 0.363 mm.

[0058] Example 3

[0059] In this embodiment 3, SiC has a multilayer interface of BN / SiC / Y2Si2O7. f The preparation process of the SiC ceramic matrix composite material is the same as in Example 1, except that: in step (b), the impregnation speed is 1000 μm / s, the impregnation time is 1 h, the pulling speed is 1000 μm / s, and the standing time is 24 h. The obtained SiC... f The thickness of the Y2Si2O7 interface layer in the / BN / SiC / Y2Si2O7 preform is approximately 720 nm. The obtained composite material underwent single-filament tensile testing, and the tensile curve is shown below. Figure 6 As shown, the fracture strength is 165 N and the fracture displacement is 0.409 mm.

[0060] Example 4

[0061] In this embodiment 4, SiC has a multilayer interface of BN / SiC / Y2Si2O7. f The preparation process of the SiC ceramic matrix composite material is the same as in Example 1, except that in step (b), the impregnation speed is 1 μm / s, the impregnation time is 1 h, the pulling speed is 1 μm / s, and the standing time is 24 h. The obtained SiC... f The thickness of the Y2Si2O7 interface layer in the / BN / SiC / Y2Si2O7 preform is approximately 380 nm.

[0062] The obtained composite material was subjected to single-filament tensile testing, and the tensile curve is as follows: Figure 7 As shown, the fracture strength is 178 N and the fracture displacement is 0.443 mm.

[0063] Comparative Example 1

[0064] In Comparative Example 1, SiC with a BN / SiC / Y2Si2O7 multilayer interface f The preparation process of the / SiC ceramic matrix composite material is the same as in Example 1, except that the Y2Si2O7 interface layer is not designed.

[0065] The densified composite material was subjected to single-filament tensile testing, and the tensile curve is shown below. Figure 8 As shown in the figure, the fracture strength is 153 N and the fracture displacement is 0.125 mm; the fracture morphology is as follows. Figure 9 As shown in the comparison with Example 1, it can be seen that preparing a Y2Si2O7 interface layer inside the composite material can adjust the crack deflection direction and increase the crack deflection path. The Y2Si2O7 interface prepared by this patent has a porous structure and has the effect of a porous interface, which improves the fracture displacement and fracture load, thereby achieving the reinforcement and toughening of the material.

[0066] Comparative Example 2

[0067] In Comparative Example 2, SiC with a BN / SiC / Y2Si2O7 multilayer interface f The preparation process of the / SiC ceramic matrix composite material is the same as in Example 1, except that: catalysis, water bath heating and aging treatment are not performed in step (3). The specific steps include:

[0068] (a) In the sol-gel method, tetraethyl orthosilicate is used as the silicon source and yttrium nitrate hexahydrate is used as the yttrium source. The molar ratio of silicon source to yttrium source is 1:1. Tetraethyl orthosilicate and yttrium nitrate hexahydrate are dissolved in ethanol to prepare the precursor solution.

[0069] (b) The precursor solution obtained in step (a) is impregnated and pulled at a speed of 100 μm / s for 1 h and a pulling speed of 100 μm / s for 24 h. The impregnated preform is dried at 120 °C for 24 h and then subjected to high-temperature pyrolysis in an argon atmosphere at a temperature of 1400 °C, a heating rate of 5 °C / min, and a holding time of 2 h.

[0070] (c) Repeat the impregnation and pyrolysis process in step (b) three times to obtain SiC. f / BN / SiC / Y2Si2O7 preform.

[0071] The precursor prepared in Comparative Example 2 could not form a homogeneous sol. After pyrolysis, SiO2 and Y2O3 separated into phases, and the resulting interfacial layer contained one or more of the following substances: SiO2, Y2O3, Y2SiO5, and Y2Si2O7. The resulting composite material was subjected to single-filament tensile testing, and the tensile curve is shown below. Figure 10 As shown, the fracture strength is 137 N and the fracture displacement is 0.328 mm.

[0072] Comparative Example 3

[0073] In Comparative Example 3, SiC with a BN / SiC / Y2Si2O7 multilayer interface f The preparation process of the SiC ceramic matrix composite material is the same as in Example 1, except that in step (b), the impregnation speed is 10000 μm / s, the impregnation time is 0.1 h, the pulling speed is 10000 μm / s, and the settling time is 0.1 h. Due to the excessively high pulling speed, the obtained precursor, after pyrolysis, easily aggregates in the fiber bundles, failing to stably coat the fibers. This fiber bundle adhesion reduces the mechanical properties of the material, resulting in a morphology as shown in the example. Figure 11 As shown. The obtained composite material was subjected to single-filament tensile testing, and the tensile curve is shown in the figure. Figure 12 As shown, the fracture strength is 137 N and the fracture displacement is 0.293 mm.

[0074] Comparative Example 4

[0075] In Comparative Example 4, SiC with a BN / SiC / Y2Si2O7 multilayer interface f The preparation process of the SiC ceramic matrix composite material is the same as in Example 1, except that the dip-coating process is not performed in step (b). f The / BN / SiC preform was directly impregnated in a sol, allowed to stand for 1 hour, and then removed. The resulting precursor, after pyrolysis, aggregated and adhered within the fiber bundles. The precursor morphology is as follows: Figure 13 As shown. The obtained composite material was subjected to single-filament tensile testing, and the tensile curve is shown in the figure. Figure 14As shown, the fracture strength is 146 N and the fracture displacement is 0.311 mm.

Claims

1. A method for preparing a silicon carbide fiber-reinforced silicon carbide ceramic matrix composite material with a BN / SiC / Y2Si2O7 multilayer interface, characterized in that, include: (1) A BN interface layer is deposited on the surface of silicon carbide fiber to prepare SiC. f / BN prefabricated body; (2) In the obtained SiC f A SiC interface layer is deposited on the surface of the BN preform to obtain SiC f / BN / SiC preform; (3) Sol-gel, dip-coating and high-temperature pyrolysis were used to prepare the SiC. f A Y2Si2O7 interface layer was prepared on the surface of the / BN / SiC preform, including: (a) Dissolve the precursor of the Y2Si2O7 interface layer in a solvent, and then add a catalyst to form a precursor solution; (b) The obtained precursor solution was heated and stirred in a water bath and then aged at room temperature. After aging and stabilization, the precursor solution was coated onto SiC by dip-coating. f The surface of the / BN / SiC preform is then dried and subjected to high-temperature pyrolysis. The water bath heating and stirring temperature is room temperature to 100°C, and the heating time is 1 to 120 hours. The aging time is 2 to 200 hours. The parameters for the impregnation-pulling method are: impregnation speed 0.1 to 1000 μm / s, impregnation time 0.1 to 72 hours; pulling speed 0.1 to 1000 μm / s, standing time 0.1 to 100 hours. The high-temperature pyrolysis temperature is 600 to 1700°C, and the time is 0.5 to 10 hours. The heating rate of the high-temperature pyrolysis is 0.1 to 10°C / minute, and the atmosphere is argon or nitrogen. (c) Repeat step (b) of dip-dipping and high-temperature pyrolysis 1 to 20 times to obtain SiC. f / BN / SiC / Y2Si2O7 preform; (4) The obtained SiC f The SiC matrix was densified using a BN / SiC / Y2Si2O7 preform to obtain SiC with a BN / SiC / Y2Si2O7 multilayer interface. f / SiC ceramic matrix composites.

2. The preparation method according to claim 1, characterized in that, In step (1), the silicon carbide fiber is a one-dimensional silicon carbide fiber bundle, a two-dimensional silicon carbide fiber cloth, a three-dimensional silicon carbide fiber braid, or a hybrid structure thereof.

3. The preparation method according to claim 2, characterized in that, The BN interface layer is prepared by chemical vapor deposition. The precursor of the BN interface layer includes a nitrogen source and a boron source. The nitrogen source is at least one of ammonia, urea, ammonium chloride, and ammonium borate. The boron source is at least one of boron trichloride, borane, boric acid, and ammonium borate.

4. The preparation method according to claim 1 or 2, characterized in that, The SiC interface layer is prepared by chemical vapor deposition, wherein the precursor of the SiC interface layer is at least one of methyltrichlorosilane, propane and silane, propane and trichlorosilane, and hexamethyldisilane. The parameters of the chemical vapor deposition method include: hydrogen as the carrier gas, the ratio of precursor to hydrogen content is 1:(2~10), the deposition temperature is 600~1800℃, and the deposition pressure is 0.1~30kPa.

5. The preparation method according to claim 1, characterized in that, In step (a), the precursor of the Y2Si2O7 interface layer includes a silicon source and a yttrium source; the silicon source is at least one of tetraethyl orthosilicate, sodium silicate, polydimethylsiloxane, and hexamethyldisiloxane; the yttrium source is at least one of yttrium nitrate hexahydrate, yttrium chloride, yttrium acetate, and yttrium isopropoxide.

6. The preparation method according to claim 1, characterized in that, In step (a), the solvent is at least one selected from anhydrous ethanol, acetone, butanol, ethyl acetate, water, and xylene; The catalyst is at least one of hydrochloric acid, nitric acid, citric acid, acetic acid, sodium hydroxide, and ammonia.

7. The preparation method according to claim 1, characterized in that, In step (b), the drying temperature is 60–180°C and the time is 2–24 hours.

8. The preparation method according to claim 1, characterized in that, In step (4), the SiC substrate is densified by chemical vapor deposition; wherein the precursor for densification of the SiC substrate is at least one of methyltrichlorosilane, propane and silane, propane and trichlorosilane, and hexamethyldisilane. The parameters of the chemical vapor deposition method include: hydrogen as the carrier gas, deposition temperature of 600–1800℃, and deposition pressure of 0.1–30 kPa.

9. A silicon carbide fiber-reinforced silicon carbide ceramic matrix composite material with a BN / SiC / Y2Si2O7 multilayer interface, prepared by the method according to any one of claims 1-8, characterized in that, The thickness of the BN interface layer is 100–1000 nm; the thickness of the SiC interface layer is 0.2–5 μm; and the thickness of the Y2Si2O7 interface layer is 100–1000 nm.

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