A high-parameter SiC / SiC ceramic matrix composite

Abstract

This invention provides a high-parameter SiC / SiC ceramic matrix composite material, relating to the field of aerospace high-temperature structural materials. This high-parameter SiC / SiC ceramic matrix composite material is composed of a SiC fiber preform, an interface phase, and a SiC matrix; the interface phase is a BN layer or a PyC+BN composite gradient layer; the SiC fiber preform adopts a 3D orthogonal braided or needle-punched structure, with a fiber volume fraction of 45%–55%; the SiC matrix is ​​prepared by a CVI+PIP composite process, with a matrix porosity ≤5%. The preparation method includes four main steps: SiC fiber preform preparation, interface phase deposition, SiC matrix densification, and environmental barrier coating. By optimizing the preform braiding structure, interface phase type, and matrix composition, combined with specific preparation processes, the composite material meets the requirements of high mechanical properties, high high-temperature oxidation resistance, high density, and high thermal conductivity. This preparation method, through CVI+PIP composite process optimization, nano-dispersed phase addition, and gradient interface phase design, overcomes existing process bottlenecks and achieves the industrial-scale preparation of high-performance composite materials.

Description

Technical Field

[0001] This invention relates to the field of high-temperature structural materials for aerospace, specifically a high-parameter SiC / SiC ceramic matrix composite material. Background Technology

[0002] SiC / SiC ceramic matrix composites combine the high temperature resistance, corrosion resistance, and low expansion properties of SiC ceramics with the high toughness and high specific strength of SiC fibers. They are core materials that can replace traditional high temperature alloys and meet the extreme service environment of aerospace above 1600℃.

[0003] Currently, SiC / SiC ceramic matrix composites generally suffer from the following technical defects: First, their mechanical properties are insufficient, with flexural strength mostly below 900 MPa and fracture toughness <18 MPa·m. 1 / 2 First, it is difficult to support the high load requirements of hot-end components of aerospace engines; second, it has poor high-temperature oxidation resistance, with an oxidation weight loss rate of >3% / 500h at 1500℃, which can easily lead to material cracking and spalling during long-term service; third, it has low density, with most products having a density of <95% and porosity of >5%, which directly affects thermal conductivity and structural stability, and the in-plane thermal conductivity is usually <60 W / (m·K), making it unsuitable for high heat flux density conditions; fourth, the manufacturing process has a long cycle and high cost, and the single CVI process is difficult to achieve densification of thick parts, while the PIP process has many cycles, resulting in low production efficiency.

[0004] Although some technologies have attempted to improve the performance of SiC / SiC through fiber modification and process optimization, they have not yet broken through the bottleneck of the core parameters of "high strength, high toughness, high oxidation resistance, and high density," failing to meet the technical requirements of next-generation aerospace equipment. Therefore, there is an urgent need to develop a high-parameter SiC / SiC ceramic matrix composite material with controllable parameters, excellent performance, and suitability for industrial production, as well as its preparation method. Summary of the Invention

[0005] Technical problems to be solved To address the technical shortcomings of existing SiC / SiC ceramic matrix composites, such as low flexural strength, insufficient fracture toughness, poor high-temperature oxidation resistance, and substandard density and thermal conductivity, this invention provides a high-parameter SiC / SiC ceramic matrix composite material and its preparation method. By optimizing the fiber preform structure, interface phase composition, matrix composition, and preparation process, multiple performance parameters of the composite material are simultaneously improved to meet the requirements of aerospace extreme operating conditions.

[0006] Technical solution To achieve the above objectives, the present invention provides the following technical solution: a high-parameter SiC / SiC ceramic matrix composite material, comprising a SiC fiber preform, an interface phase, and a SiC matrix; the interface phase is a BN layer or a PyC+BN composite gradient layer; the SiC fiber preform adopts a 3D orthogonal braided or needle-punched structure, with a fiber volume fraction of 45%–55%; the SiC matrix is ​​prepared by a CVI+PIP composite process, with a matrix porosity ≤5%.

[0007] Preferably, the SiC fiber is one of the third-generation or fourth-generation SiC fibers, with a tensile strength ≥3.5GPa and a modulus ≥400GPa.

[0008] Preferably, when the interface phase is a BN layer, the thickness of the BN layer is 100~300nm; when the interface phase is a PyC+BN composite gradient layer, it consists of a PyC layer, a BN layer, and a SiC transition layer from the inside out, wherein the thickness of the PyC layer is 50~100nm, the thickness of the BN layer is 100~200nm, and the thickness of the SiC transition layer is 30~50nm.

[0009] Preferably, at least one nano-dispersed phase selected from B4C, TaB2, and ZrC is added to the SiC matrix, the nano-dispersed phase having a particle size of 50-200 nm and an addition amount of 2% to 8% of the mass of the SiC matrix.

[0010] Preferably, the surface of the high-parameter SiC / SiC ceramic matrix composite material is coated with an environmental barrier coating, which is a rare earth silicate coating, specifically at least one of Yb2SiO5, Lu2SiO5, and HfO2, and the coating thickness is 50~200μm.

[0011] Preferably, a method for preparing a high-parameter SiC / SiC ceramic matrix composite material includes the following steps: (1) Preparation of SiC fiber preform: Select third-generation or fourth-generation SiC fibers and prepare preforms using 3D orthogonal weaving or needle punching processes, controlling the fiber volume fraction to be 45% to 55%; (2) Interfacial phase deposition: BN interfacial phase is deposited on the surface of SiC fiber preform using the CVI method. The deposition temperature is 900~1100℃, the deposition pressure is 500~1000Pa, and the deposition time is 2~4h to obtain a preform with a BN layer thickness of 100~300nm; or PyC, BN, and SiC transition layers are deposited sequentially to form a composite gradient interfacial phase. (3) Dense SiC matrix: The matrix was impregnated using a CVI+PIP composite process. The CVI process parameters were: temperature 1000~1200℃, pressure 800~1500Pa, and the precursor was methyltrichlorosilane. The PIP process parameters were: the precursor was polycarbosilane, the solid content was 40%~60%, the pyrolysis temperature was 1000~1200℃, the pyrolysis time was 2~3h, and the cycle was 3~5 times until the matrix density was ≥97% and the porosity was ≤5%. (4) Environmental barrier coating: A rare earth silicate environmental barrier coating is applied to the surface of the composite material using plasma spraying technology. The spraying power is 30~50kW, the spraying distance is 80~120mm, and the coating thickness is controlled to be 50~200μm. (5) High-temperature heat treatment and performance determination.

[0012] Preferably, in step (3), the CVI process deposition time is 3 to 5 hours, the PIP process pyrolysis atmosphere is argon, and the pyrolysis heating rate is 5 to 10 °C / min.

[0013] Preferably, in step (4), the particle size of the raw material powder for the rare earth silicate environmental barrier coating is 10~50μm, and the surface of the composite material is sandblasted before spraying. The sandblasting pressure is 0.3~0.5MPa and the sandblasting time is 1~3min.

[0014] Beneficial effects This invention provides a high-parameter SiC / SiC ceramic matrix composite material. It possesses the following beneficial effects: 1. Significantly improved performance parameters: The composite material's flexural strength is ≥1100 MPa, an improvement of ≥20% compared to existing products; fracture toughness is ≥22 MPa·m. 1 / 2 The performance is improved by ≥25%; the oxidation weight loss at 1600℃ / 1000h is ≤1%, and the antioxidant life is improved by ≥2 times; the density is ≥97%, the porosity is ≤3%, and the in-plane thermal conductivity is ≥80 W / (m·K), fully meeting the performance requirements of aerospace extreme working conditions.

[0015] 2. Strong process adaptability: The CVI+PIP composite densification process reduces the number of PIP cycles, shortening the production cycle by more than 40% compared to the single CVI process. It can achieve uniform densification of thick parts (>10 mm) and complex structural composite materials, reducing production costs.

[0016] 3. Excellent structural stability: The gradient interface phase design and the addition of nano-dispersed phases effectively alleviate interface stress, inhibit crack propagation, improve the thermal shock resistance and fatigue life of composite materials, and have higher reliability in long-term service.

[0017] 4. Wide range of applications: It can be adapted to the hot-end components of various high-temperature equipment such as rocket engines, aerospace vehicles, and high-end gas turbines, and has good market promotion and application prospects. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the high-parameter SiC / SiC ceramic matrix composite material of the present invention; Figure 2 This is a process flow diagram of the preparation method of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] like Figure 1-2 As shown, this invention provides a high-parameter SiC / SiC ceramic matrix composite material, characterized in that it is composed of a SiC fiber preform, an interface phase, and a SiC matrix; the interface phase is a BN layer or a PyC+BN composite gradient layer; the SiC fiber preform adopts a 3D orthogonal braided or needle-punched structure, with a fiber volume fraction of 45%–55%; the SiC matrix is ​​prepared by a CVI+PIP composite process, with a matrix porosity ≤5%. The SiC fiber is one of the third or fourth generation SiC fibers, with a tensile strength ≥3.5GPa and a modulus ≥400GPa. When the interface phase is a BN layer, the thickness of the BN layer is 100~300nm. When the interface phase is a PyC+BN composite gradient layer, the layers from the inside out are PyC layer, BN layer, and SiC transition layer, with the PyC layer thickness being 50~100nm, the BN layer thickness being 100~200nm, and the SiC transition layer thickness being 30~50nm. At least one nano-dispersed phase from B4C, TaB2, and ZrC is added to the SiC matrix, with a nano-dispersed phase particle size of 50~200nm and an addition amount of 2%~8% of the SiC matrix mass. The surface of the high-parameter SiC / SiC ceramic matrix composite material is coated with an environmental barrier coating, which is a rare earth silicate coating, specifically at least one from Yb2SiO5, Lu2SiO5, and HfO2, with a coating thickness of 50~200μm. Example 1; Preparation of a high-parameter SiC / SiC ceramic matrix composite material: 1. Preparation of SiC fiber preform: Third-generation SiC fibers (tensile strength 3.6 GPa, modulus 410 GPa) were selected, and the preform was prepared by 3D orthogonal weaving process, with the fiber volume fraction controlled at 50%.

[0021] 2. Interfacial phase deposition: BN interfacial phase was deposited on the surface of SiC fiber preform using the CVI method at a deposition temperature of 1000℃, a deposition pressure of 800Pa, and a deposition time of 3h, resulting in a preform with a BN layer thickness of 200nm.

[0022] 3. SiC matrix densification: The matrix was impregnated using a CVI+PIP composite process. The CVI process parameters were: temperature 1100℃, pressure 1200Pa, precursor methyltrichlorosilane, deposition time 4h; the PIP process parameters were: precursor polycarbosilane, solid content 50%, pyrolysis temperature 1100℃, pyrolysis atmosphere argon, heating rate 8℃ / min, pyrolysis time 2.5h, and 4 cycles. The final SiC matrix was obtained with a porosity of 4%, and the composite material had a density of 97.5% and a porosity of 2.5%.

[0023] 4. Environmental barrier coating: A Yb2SiO5 environmental barrier coating is applied to the surface of the composite material using plasma spraying technology. The spraying power is 40kW, the spraying distance is 100mm, the raw material powder particle size is 30μm, and the surface of the composite material is sandblasted before spraying. The sandblasting pressure is 0.4MPa, the sandblasting time is 2min, and the coating thickness is 120μm. 5. High-temperature heat treatment and performance finalization.

[0024] Performance Test 1 The performance of the SiC / SiC ceramic matrix composite material prepared in this embodiment was tested, and the results are as follows: ; Example 2 Preparation of a high-parameter SiC / SiC ceramic matrix composite material: 1. Preparation of SiC fiber preform: Fourth-generation SiC fiber (tensile strength 3.7 GPa, modulus 420 GPa) was selected, and the preform was prepared by needle punching process, with the fiber volume fraction controlled at 45%.

[0025] 2. Interfacial phase deposition: PyC, BN, and SiC transition layers were sequentially deposited using the CVI method to form a composite gradient interfacial phase. The deposition temperature was 950℃, the deposition pressure was 600Pa, and the deposition times were 2h for the PyC layer, 2.5h for the BN layer, and 1h for the SiC transition layer, respectively, to obtain a preform with a PyC layer thickness of 60nm, a BN layer thickness of 150nm, and a SiC transition layer thickness of 40nm.

[0026] 3. SiC matrix densification: A CVI+PIP composite process was adopted. The CVI process temperature was 1000℃, the pressure was 1000Pa, and the deposition time was 3h. The PIP process solid content was 40%, the pyrolysis temperature was 1000℃, the heating rate was 5℃ / min, the pyrolysis time was 2h, and the cycle was 3 times. 5% of B4C nano-dispersed phase (particle size 80nm) by mass of SiC matrix was added. The final matrix porosity was 3%, the composite material density was 98%, and the porosity was 2%.

[0027] 4. Environmental barrier coating: Apply Lu2SiO5 environmental barrier coating, spray power 35kW, spray distance 90mm, raw material powder particle size 20μm, sandblasting pressure 0.3MPa, sandblasting time 1.5min, coating thickness 80μm; 5. High-temperature heat treatment and performance finalization.

[0028] Performance Test 2 The SiC / SiC ceramic matrix composite material prepared in this embodiment was subjected to performance testing, and the results are as follows: ; Example 3 Preparation of a high-parameter SiC / SiC ceramic matrix composite material: 1. Preparation of SiC fiber preform: Third-generation SiC fibers were selected and 3D orthogonally woven, with a fiber volume fraction of 55%.

[0029] 2. Interfacial phase deposition: BN interfacial phase deposition, temperature 1100℃, pressure 1000Pa, deposition time 4h, BN layer thickness 300nm.

[0030] 3. SiC matrix densification: CVI process temperature 1200℃, pressure 1500Pa, deposition time 5h; PIP process solid content 60%, pyrolysis temperature 1200℃, heating rate 10℃ / min, pyrolysis time 3h, 5 cycles, adding 8% of the SiC matrix mass of TaB2 nano-dispersed phase (particle size 150nm), matrix porosity 5%, composite material density 97%, porosity 3%.

[0031] 4. Environmental barrier coating: Apply HfO2-doped Yb2SiO5 composite environmental barrier coating, with a spraying power of 50kW, a spraying distance of 120mm, a raw material powder particle size of 50μm, a sandblasting pressure of 0.5MPa, a sandblasting time of 3min, and a coating thickness of 200μm. 5. High-temperature heat treatment and performance finalization.

[0032] Performance Test 3 The SiC / SiC ceramic matrix composite material prepared in this embodiment was subjected to performance testing, and the results are as follows: ; Comparative Example 1 Preparation of a SiC / SiC ceramic matrix composite material: SiC / SiC ceramic matrix composites were prepared using a single CVI process without the addition of nano-dispersed phases or the application of an environmental barrier coating. The remaining steps were the same as in Example 1.

[0033] Performance Test 4 The performance test results are as follows: ; Comparative Example 2 Preparation of a SiC / SiC ceramic matrix composite material: The CVI+PIP composite process was adopted, but the PIP process cycle was 2 times, and there was no gradient interface phase design. The remaining steps were the same as in Example 1.

[0034] Performance Test 5 The performance test results are as follows: ; Comparative analysis of the above embodiments and comparative examples shows that the present invention significantly improves the comprehensive performance of SiC / SiC ceramic matrix composites by employing high-parameter SiC fibers, optimizing the interfacial phase structure, combining CVI+PIP composite densification process with the addition of nano-dispersed phases, and coating with an environmental barrier coating. Compared with the comparative examples, the composites prepared in the embodiments have higher density (97%–98%), flexural strength (1120–1180 MPa), and fracture toughness (22–24 MPa·m). 1 / 2 With an in-plane thermal conductivity of 80–85 W / (m·K) and a lower oxidation weight loss rate (0.7%–1%) at 1600℃ / 1000h, the mechanical properties, antioxidant properties, and thermophysical properties of this invention are significantly improved, demonstrating the advanced nature and effectiveness of the technical solution of this invention.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-parameter SiC / SiC ceramic matrix composite material, characterized in that: It is composed of SiC fiber preform, interface phase and SiC matrix; the interface phase is BN layer or PyC+BN composite gradient layer; the SiC fiber preform adopts 3D orthogonal weaving or needle punching structure, and the fiber volume fraction is 45% to 55%; the SiC matrix is ​​prepared by CVI+PIP composite process and the matrix porosity is ≤5%.

2. The high-parameter SiC / SiC ceramic matrix composite material according to claim 1, characterized in that: The SiC fiber is one of the third or fourth generation SiC fibers, with a tensile strength ≥3.5GPa and a modulus ≥400GPa.

3. The high-parameter SiC / SiC ceramic matrix composite material according to claim 1, characterized in that: When the interface phase is a BN layer, the thickness of the BN layer is 100~300nm; when the interface phase is a PyC+BN composite gradient layer, the layers from the inside out are a PyC layer, a BN layer, and a SiC transition layer, wherein the thickness of the PyC layer is 50~100nm, the thickness of the BN layer is 100~200nm, and the thickness of the SiC transition layer is 30~50nm.

4. The high-parameter SiC / SiC ceramic matrix composite material according to claim 1, characterized in that: The SiC matrix is ​​supplemented with at least one nano-dispersed phase selected from B4C, TaB2, and ZrC. The nano-dispersed phase has a particle size of 50-200 nm and is added in an amount of 2% to 8% of the mass of the SiC matrix.

5. The high-parameter SiC / SiC ceramic matrix composite material according to claim 1, characterized in that: The surface of the high-parameter SiC / SiC ceramic matrix composite material is coated with an environmental barrier coating, which is a rare earth silicate coating, specifically at least one of Yb2SiO5, Lu2SiO5, and HfO2, with a coating thickness of 50~200μm.

6. A method for preparing a high-parameter SiC / SiC ceramic matrix composite material, characterized in that, Includes the following steps: (1) Preparation of SiC fiber preform: Select third-generation or fourth-generation SiC fibers and prepare preforms using 3D orthogonal weaving or needle punching processes, controlling the fiber volume fraction to be 45% to 55%; (2) Interfacial phase deposition: BN interfacial phase is deposited on the surface of SiC fiber preform using the CVI method. The deposition temperature is 900~1100℃, the deposition pressure is 500~1000Pa, and the deposition time is 2~4h to obtain a preform with a BN layer thickness of 100~300nm; or PyC, BN, and SiC transition layers are deposited sequentially to form a composite gradient interfacial phase. (3) Dense SiC matrix: The matrix was impregnated using a CVI+PIP composite process. The CVI process parameters were: temperature 1000~1200℃, pressure 800~1500Pa, and the precursor was methyltrichlorosilane. The PIP process parameters were: the precursor was polycarbosilane, the solid content was 40%~60%, the pyrolysis temperature was 1000~1200℃, the pyrolysis time was 2~3h, and the cycle was 3~5 times until the matrix density was ≥97% and the porosity was ≤5%. (4) Environmental barrier coating: A rare earth silicate environmental barrier coating is applied to the surface of the composite material using plasma spraying technology. The spraying power is 30~50kW, the spraying distance is 80~120mm, and the coating thickness is controlled to be 50~200μm. (5) High-temperature heat treatment and performance determination.

7. The method for preparing a high-parameter SiC / SiC ceramic matrix composite material according to claim 6, characterized in that: In step (3), the deposition time of CVI process is 3 to 5 hours, the pyrolysis atmosphere of PIP process is argon, and the pyrolysis heating rate is 5 to 10 °C / min.

8. The method for preparing a high-parameter SiC / SiC ceramic matrix composite material according to claim 6, characterized in that: In step (4), the particle size of the raw material powder for the rare earth silicate environmental barrier coating is 10~50μm. Before spraying, the surface of the composite material is sandblasted with a sandblasting pressure of 0.3~0.5MPa and a sandblasting time of 1~3min.

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