SiC / SiC composite material for hot end components of aircraft engines and preparation method thereof

Abstract

The invention discloses a SiC / SiC composite material for hot-end components of an aero-engine and a preparation method thereof, relating to the technical field of SiC / SiC composite materials for hot-end components of an aero-engine. During the preparation, SiC fibers are respectively woven into three types of two-dimensional plain fiber cloths with different surface densities by warp and weft. A certain number of the three types of fiber cloths are laid flat and continuously needle-punched to obtain a variable-density SiC fiber preform. BN interface layer deposition and chemical vapor deposition are successively performed, followed by vacuum impregnation with an epoxy resin impregnation solution and heating for curing. A precursor solution is vacuum impregnated and dried, and the epoxy resin is decomposed at 500°C. Subsequently, heating and pyrolysis are continuously performed to generate a SiC matrix, thereby obtaining a SiC / SiC composite material with an internal void structure. The invention can prepare a ceramic-based composite material that can be rapidly densified, can withstand high temperatures of 1500°C, has certain thermal insulation properties and good mechanical properties, and can be effectively used in hot-end components of an aero-engine.

Description

Technical Field

[0001] The present invention relates to the technical field of SiC / SiC composite materials for hot end components of aircraft engines, and in particular to a SiC / SiC composite material for hot end components of aircraft engines and a preparation method thereof. Background Art

[0002] The turbine system of an aircraft engine is an important subsystem that converts part of the thermal energy pressure of high-temperature, high-pressure combustion gas into mechanical work, and plays a key role in the engine's thrust-to-weight ratio. As the demand for aircraft engine performance continues to increase, higher requirements are placed on the lightweight, high-temperature resistance, mechanical properties, and thermal insulation properties of the hot end component materials. Continuous fiber-reinforced SiC / SiC ceramic matrix composites (hereinafter referred to as SiC / SiC composites) have excellent physical and chemical properties such as high-temperature resistance, oxidation resistance, thermal shock resistance, and high strength. The density of this material is only 1 / 3-1 / 4 of that of high-temperature alloys. Without air cooling and thermal barrier coatings, the operating temperature can be increased by 150-350°C compared to high-temperature alloys, and the potential operating temperature can reach 1650°C. It is a new generation of strategic thermal structural materials in the field of aircraft engines and industrial gas turbines.

[0003] Traditional SiC / SiC composites are mostly formed from fiber preforms of uniform density. Due to the high price of SiC fiber, if SiC fiber cloth of uniform density is used to form the preform, the amount of SiC fiber used will increase, which will increase the preparation cost of the composite to a certain extent. At the same time, the use of highly densified uniform density SiC / SiC composites in the aviation field will increase the load weight of the aircraft due to the internal solid structure, reducing economic benefits. In addition, uniform density SiC / SiC composites require multiple densifications during the densification process, which increases the consumption of raw materials for the preparation of the SiC matrix, resulting in a long preparation cycle and high preparation costs. Currently available information shows that the patent number CN108794035A proposes a method for preparing high-temperature resistant ceramic materials. The material is modified by silicon carbide particles to form silicon nitride fibers, which has good bending resistance and can withstand high temperatures of 1850°C. Patent number CN115821098A proposes a high-temperature resistant ceramic-based composite material and its preparation method. This method uses a ball mill to mix multiple metals and transition metal elements, and then vacuum sintering and pressing to form a high-temperature resistant ceramic-based composite material with excellent bending resistance. The above two patents only assess and evaluate high-temperature resistance and bending resistance, and the preparation process is relatively complex. High-temperature resistant materials used in aircraft engine hot end components often operate in more severe and demanding environments, withstanding high temperatures while also enduring complex stresses such as increased tension and bending.

[0004] Therefore, in order to solve the above problems, there is an urgent need to develop a preparation method for ceramic composite materials used in the hot end components of aircraft engines, so that the prepared ceramic-based composite materials have light weight, high temperature resistance, excellent mechanical properties and certain thermal insulation properties, further meeting the needs of the hot end components of aircraft engines. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a SiC / SiC composite material for the hot end components of aircraft engines and a preparation method thereof, which can quickly densify, withstand high temperatures of 1500°C, have certain thermal insulation properties and good mechanical properties, and can be effectively used in the hot end components of aircraft engines.

[0006] The present invention solves the above technical problems with the following technical solution: a method for preparing a SiC / SiC composite for an aircraft engine hot end component is provided, comprising the following steps:

[0007] (1) SiC fibers were bundled in 6×6 bundles / cm 2 , 7×7 bundles / cm 2 and 8×8 bundles / cm 2 The weaving density is woven into three kinds of two-dimensional plain fiber cloths;

[0008] (2) The two-dimensional plain fiber cloth obtained in step (1) was woven into a 8×8 bundle / cm 2 -7×7 bundles / cm 2 -6×6 bundles / cm 2 -7×7 bundles / cm 2 -8×8 bundles / cm 2 The layers are laid sequentially, then clamped by a graphite fixture and continuously needled to obtain a SiC fiber preform with a density gradient;

[0009] (3) placing the SiC fiber preform with a density gradient obtained in step (2) into a boron nitride deposition furnace, and depositing a BN interface layer on the surface to obtain a fiber preform with a deposited BN interface layer;

[0010] (4) placing the fiber preform deposited with the BN interface layer obtained in step (3) into a SiC vapor deposition furnace to perform SiC chemical vapor deposition to obtain a semi-densified SiC / SiC composite;

[0011] (5) The semi-densified SiC / SiC composite obtained in step (4) is separated from the graphite fixture and immersed in an epoxy resin impregnation solution at a pressure of -0.1 MPa, maintained for 0.5-0.6 hours, and then taken out and dried and cured at a constant temperature of 80°C for 2-3 hours. The impregnation and curing steps are repeated until the weight gain is 5-10%, thereby obtaining a SiC / SiC composite with thermosetting resin infiltrated in the center;

[0012] (6) immersing the SiC / SiC composite obtained in step (5) with the thermosetting resin infiltrated at the center into an organic precursor solution at a pressure of -0.1 MPa for 0.5-0.6 h, repeating the immersion step until the weight gain is 18-22%, and then curing at a temperature of 120-150° C. for 2-3 h, and then heating to 500° C. at a heating rate of 1-10° C. / min in an argon atmosphere and holding for 5 h, and finally heating to 1200° C. at a heating rate of 5° C. / min to obtain a SiC / SiC composite with a void structure;

[0013] (7) The SiC / SiC composite material with a void structure obtained in step (6) is post-treated and oxidized in a muffle furnace at 700° C. for 5-6 hours, cooled to room temperature, cleaned and dried to obtain a SiC / SiC composite material for hot end components of an aircraft engine.

[0014] Furthermore, in step (1), the SiC fibers contain Si, C, O, and Al, have an average diameter of 10 μm, have 1600 fiber bundles, and a density of 3-3.2 g / cm 3 , the atomic ratio of C / Si is 0.92-0.95, the tensile strength is 2.4Gpa, the fracture strain is 0.7%, and the temperature resistance is 1800℃.

[0015] Furthermore, in step (1), the average thickness of the two-dimensional plain woven fiber cloth is 0.2-0.3 mm.

[0016] Furthermore, in step (1), the average thickness of the two-dimensional plain woven fiber cloth is 0.22 mm.

[0017] Furthermore, in step (2), three layers of each weaving density are stacked to form a total of 15 layers of fiber laminated cloth.

[0018] Furthermore, in step (2), when the whole is continuously needled, the needle-punching direction is perpendicular to the plane where the fiber cloth is located, and the number of needle-punching processes is the number of needles per unit area, and the number of needles per cm is 5-10 needles / cm. 2 .

[0019] Furthermore, in step (2), the average thickness of the SiC fiber preform with density gradient is 2.9-3.4 mm.

[0020] Furthermore, in step (2), the average thickness of the SiC fiber preform with density gradient is 3.2 mm.

[0021] Furthermore, in step (3), when the BN interface layer is deposited, argon is used as the protective gas and hydrogen is used as the carrier gas. Ammonia and boron trichloride gases are introduced at a temperature of 1000°C, with ventilation rates of 0.25L / min and 0.15L / min, respectively, and the deposition time is 10-20h.

[0022] Furthermore, in step (3), the average thickness of the BN interface layer is 200-500 nm.

[0023] Furthermore, in step (3), the average thickness of the BN interface layer is 340 nm.

[0024] Furthermore, in step (4), the average density of the semi-densified SiC / SiC composite is 2.2-2.4 g / cm 3 .

[0025] Furthermore, in step (5), the epoxy resin impregnation liquid is prepared by the following method: epoxy resin, diethylenetriamine, acetone and xylene are mixed in a mass ratio of 12:1:7:10, magnetically stirred, and ultrasonically dispersed for 0.5-1h to obtain the epoxy resin impregnation liquid.

[0026] Furthermore, in step (5), the impregnation and curing step is repeated until the weight gain reaches 8%.

[0027] At this time, the vacuum environment is -0.1 MPa, so that the impregnation liquid is impregnated into the interior of the composite material under the action of atmospheric pressure.

[0028] Furthermore, in step (6), the organic precursor solution is at least one of polycarbosilane, polymethylsilane and polypropylene hydroxycarbosilane.

[0029] Furthermore, in step (6), the dipping step is repeated until the weight gain reaches 20%.

[0030] Furthermore, in step (6), the average density of the SiC / SiC composite with a void structure is 2.5-2.9 g / cm 3 .

[0031] Furthermore, in step (6), the average density of the SiC / SiC composite with a void structure is 2.8 g / cm 3 .

[0032] Furthermore, in step (6), the temperature is raised to 500°C and maintained. At this temperature, the thermosetting resin inside the SiC / SiC composite decomposes. The temperature is then raised to 1200°C, and the precursor is pyrolyzed in a high-temperature inert gas environment to generate a SiC matrix between the fiber bundles and the open pores of the fibers.

[0033] Furthermore, in step (7), during post-processing, dust on the surface of the composite material is removed, the surface is polished until it is smooth, and burrs on the edges and corners are removed.

[0034] The present invention uses a new type of SiC fiber in 6×6 bundles / cm 2 , 7×7 bundles / cm 2 and 8×8 bundles / cm 2The fabric is woven into a fiber fabric with varying warp and weft densities, and a variable-density fiber preform is prepared according to a specific layering method. Combined with the CVI+PIP process, the resulting SiC / SiC composite can withstand temperatures of 1500°C. Furthermore, by sewing SiC fibers into three different two-dimensional plain weaves with varying warp and weft densities, and then laying a certain number of these different fabrics in a specific pattern and continuously needle-punching them, the structure, density, and volume fraction of the fiber preform can be controlled and optimized.

[0035] At the same time, a vacuum infusion process was used to immerse the SiC / SiC composite in an epoxy resin solution. Atmospheric pressure and capillary forces generated by solvent evaporation allowed the epoxy resin to penetrate into the voids in the low-density areas of the SiC / SiC composite. The epoxy resin was then heated and cured to pre-fill the voids within the SiC / SiC composite. Subsequently, a PIP process was used to fill the remaining voids in the SiC / SiC composite with a ceramic precursor. Simultaneously, the epoxy resin within the composite was removed at high temperature and further pyrolyzed to form a SiC matrix. This successfully produced a SiC / SiC composite with an internal void structure.

[0036] The present invention also provides a SiC / SiC composite material for hot end components of an aero-engine, which is prepared by the method for preparing the SiC / SiC composite material for hot end components of an aero-engine.

[0037] The present invention has the following beneficial effects:

[0038] 1. The present invention is based on 6×6 (beams) / cm 2 , 7×7 (bundles) / cm 2 , 8×8 (bundles) / cm 2 The SiC fibers are woven into three kinds of two-dimensional plain fiber cloths with different surface densities by warp and weft weaving. A certain number of the three kinds of fiber cloths are laid flat in a certain manner and continuously needle-punched to obtain a SiC fiber preform with a variable density structure with few warp and weft voids in the upper and lower parts and more warp and weft voids in the center. The preform is successively subjected to BN interface layer deposition and chemical vapor deposition of SiC to achieve semi-densification. The semi-densified composite is then vacuum-impregnated with a mixed solution of epoxy resin (EP), diethylenetriamine (DETA), acetone (AC) and xylene (DMB) and heated to cure. After curing, it is vacuum-impregnated with a ceramic precursor solution and dried. The epoxy resin is decomposed in an argon environment at 500°C and then continuously heated to 1200°C for pyrolysis to generate a SiC matrix, thereby obtaining a SiC / SiC composite with an internal void structure. This method can prepare a ceramic matrix composite material that can be rapidly densified, withstand high temperatures of 1500°C, have certain thermal insulation properties and good mechanical properties, and can be effectively used in the hot end components of aircraft engines.

[0039] 2. The present invention uses a preform formed from a new type of SiC fiber and a SiC / SiC composite with a void structure prepared through CVI and epoxy resin impregnation, curing and cracking processes. While the plate has an internal void structure, it can still maintain good mechanical properties and can withstand temperatures of 1500°C.

[0040] 3. During the densification process of SiC / SiC composites with void structures, epoxy resin is impregnated into the interior of the plate for filling, which not only helps to quickly densify the SiC / SiC composites, but also reduces the consumption of raw materials required to generate the SiC matrix, which has the significant advantages of reducing preparation costs and shortening preparation cycles.

[0041] 4. Compared with the SiC / SiC composite with a highly densified uniform structure, the SiC / SiC composite with a void structure prepared by the present invention is lighter. At the same time, the internal void structure reduces the thermal conductivity of the material to a certain extent, making the SiC / SiC composite with a variable density structure have good thermal insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a physical image of the SiC / SiC composite material for the hot end component of an aero-engine obtained in Example 2;

[0043] Figure 2 CT schematic diagram of the cross section of the SiC / SiC composite material for the hot end component of an aero-engine obtained in Example 2;

[0044] Figure 3 Schematic diagram of the SiC matrix after cracking of the ceramic precursor. DETAILED DESCRIPTION

[0045] The principles and features of the present invention are described below. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. In the examples, where specific conditions are not specified, conventional conditions or manufacturer-recommended conditions were used. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0046] Example 1

[0047] A method for preparing a SiC / SiC composite material for an aircraft engine hot end component comprises the following steps:

[0048] (1) SiC fibers were bundled in 6×6 bundles / cm 2 , 7×7 bundles / cm 2 and 8×8 bundles / cm 2 The weaving density is woven into three kinds of two-dimensional plain fiber cloths; the elements contained in the SiC fiber are Si, C, O and Al, the average diameter is 10μm, the fiber tow is 1600, and the density is 3.1g / cm 3, the atomic ratio of C / Si is 0.92-0.95, the tensile strength is 2.4GPa, the breaking strain is 0.7%, and the temperature resistance is 1800℃; the average thickness of the two-dimensional plain fiber cloth is 0.2-0.3mm;

[0049] (2) The two-dimensional plain fiber cloth obtained in step (1) was woven into a 8×8 bundle / cm 2 -7×7 bundles / cm 2 -6×6 bundles / cm 2 -7×7 bundles / cm 2 -8×8 bundles / cm 2 The layers are laid sequentially, with three layers of each weaving density stacked together to form a total of 15 layers of fiber laminated cloth. The preform is then clamped by a graphite fixture and continuously needled to obtain a SiC fiber preform with a density gradient. During the continuous needled process, the needled direction is perpendicular to the plane of the fiber cloth. The number of needled processes is the number of needles per unit area, and the number of needles / cm 2 The average thickness of the SiC fiber preform with density gradient is 2.9 mm.

[0050] (3) placing the SiC fiber preform with a density gradient obtained in step (2) into a boron nitride deposition furnace, and depositing a BN interface layer on the surface to obtain a fiber preform with a BN interface layer deposited thereon; during the BN interface layer deposition, argon was used as a protective gas, hydrogen was used as a carrier gas, ammonia and boron trichloride gas were introduced at a temperature of 1000° C., the ventilation rates were 0.25 L / min and 0.15 L / min, respectively, and the deposition time was 10 h; the average thickness of the BN interface layer was 200 nm;

[0051] (4) The fiber preform with the BN interface layer deposited in step (3) is placed in a SiC vapor deposition furnace to perform SiC chemical vapor deposition to obtain a semi-densified SiC / SiC composite; the average density of the semi-densified SiC / SiC composite is 2.2 g / cm 3 ;

[0052] (5) The semi-densified SiC / SiC composite obtained in step (4) is separated from the graphite fixture, immersed in an epoxy resin impregnation solution at a pressure of -0.1 MPa, maintained for 0.5 h, and then taken out, and then dried and cured at a constant temperature of 80°C for 2 h, and the impregnation and curing steps are repeated until the weight gain is 5%, thereby obtaining a SiC / SiC composite with thermosetting resin infiltrated in the center; the epoxy resin impregnation solution is prepared by the following method: epoxy resin, diethylenetriamine, acetone and xylene are mixed in a mass ratio of 12:1:7:10, magnetically stirred, and ultrasonically dispersed for 0.5 h to obtain the epoxy resin impregnation solution;

[0053] (6) The SiC / SiC composite obtained in step (5) and infiltrated with a thermosetting resin at its center is immersed in an organic precursor solution at a pressure of -0.1 MPa and maintained for 0.5 h. The immersion step is repeated until the weight gain is 18%, and then cured at 120°C for 2 h. The SiC / SiC composite is then heated to 500°C at a heating rate of 2°C / min in an argon atmosphere and maintained for 5 h. Finally, the SiC / SiC composite is heated to 1200°C at a heating rate of 5°C / min to obtain a SiC / SiC composite having a void structure. The organic precursor solution is at least one of polycarbosilane, polymethylsilane and polypropylene hydroxycarbosilane. The average density of the SiC / SiC composite having a void structure is 2.5 g / cm 3 ;

[0054] (7) The SiC / SiC composite material with a void structure obtained in step (6) is post-treated, oxidized in a muffle furnace at 700° C. for 5 h, cooled to room temperature, cleaned and dried to obtain a SiC / SiC composite material for an aircraft engine hot end component; during post-treatment, dust on the composite material surface is removed, the surface is polished until it is smooth, and burrs on the edges and corners are removed.

[0055] Example 2

[0056] A method for preparing a SiC / SiC composite material for an aircraft engine hot end component comprises the following steps:

[0057] (1) SiC fibers were bundled in 6×6 bundles / cm 2 , 7×7 bundles / cm 2 and 8×8 bundles / cm 2 The weaving density is woven into three kinds of two-dimensional plain fiber cloths; the elements contained in the SiC fiber are Si, C, O and Al, the average diameter is 10μm, the fiber tow is 1600, and the density is 3.1g / cm 3 , the atomic ratio of C / Si is 0.92-0.95, the tensile strength is 2.4GPa, the breaking strain is 0.7%, and the temperature resistance is 1800℃; the average thickness of the two-dimensional plain fiber cloth is 0.22mm;

[0058] (2) The two-dimensional plain fiber cloth obtained in step (1) was woven into a 8×8 bundle / cm 2 -7×7 bundles / cm 2 -6×6 bundles / cm 2 -7×7 bundles / cm 2 -8×8 bundles / cm 2 The layers are laid sequentially, with three layers of each weaving density stacked together to form a total of 15 layers of fiber laminated cloth. The preform is then clamped by a graphite fixture and continuously needled to obtain a SiC fiber preform with a density gradient. During the continuous needled process, the needled direction is perpendicular to the plane of the fiber cloth. The number of needled processes is the number of needles per unit area, and the number of needles / cm 2The average thickness of the SiC fiber preform with density gradient is 3.2 mm.

[0059] (3) placing the SiC fiber preform with a density gradient obtained in step (2) into a boron nitride deposition furnace, and depositing a BN interface layer on the surface to obtain a fiber preform with a BN interface layer deposited thereon; during the BN interface layer deposition, argon was used as a protective gas, hydrogen was used as a carrier gas, ammonia and boron trichloride gas were introduced at a temperature of 1000° C., the ventilation rates were 0.25 L / min and 0.15 L / min, respectively, and the deposition time was 15 h; the average thickness of the BN interface layer was 340 nm;

[0060] (4) placing the fiber preform with the BN interface layer deposited in step (3) into a SiC vapor deposition furnace to perform SiC chemical vapor deposition to obtain a semi-densified SiC / SiC composite; the average density of the semi-densified SiC / SiC composite is 2.3 g / cm 3 ;

[0061] (5) The semi-densified SiC / SiC composite obtained in step (4) is separated from the graphite fixture, immersed in an epoxy resin impregnation solution at a pressure of -0.1 MPa, maintained for 0.5 h, and then taken out, and then dried and cured at a constant temperature of 80°C for 2 h, and the impregnation and curing steps are repeated until the weight gain is 8%, thereby obtaining a SiC / SiC composite with thermosetting resin infiltrated in the center; the epoxy resin impregnation solution is prepared by the following method: epoxy resin, diethylenetriamine, acetone and xylene are mixed in a mass ratio of 12:1:7:10, magnetically stirred, and ultrasonically dispersed for 0.5 h to obtain the epoxy resin impregnation solution;

[0062] (6) The SiC / SiC composite obtained in step (5) and infiltrated with a thermosetting resin at the center is immersed in an organic precursor solution at a pressure of -0.1 MPa and maintained for 0.5 h. The immersion step is repeated until the weight gain is 20%, and then cured at 130°C for 2 h. The SiC / SiC composite is then heated to 500°C at a heating rate of 5°C / min in an argon atmosphere and maintained for 5 h. Finally, the SiC / SiC composite is heated to 1200°C at a heating rate of 5°C / min to obtain a SiC / SiC composite with a void structure. The organic precursor solution is at least one of polycarbosilane, polymethylsilane and polypropylene hydroxycarbosilane. The average density of the SiC / SiC composite with a void structure is 2.8 g / cm 3 ;

[0063] (7) The SiC / SiC composite material with a void structure obtained in step (6) is post-treated, oxidized in a muffle furnace at 700° C. for 5 h, cooled to room temperature, cleaned and dried to obtain a SiC / SiC composite material for an aircraft engine hot end component; during post-treatment, dust on the composite material surface is removed, the surface is polished until it is smooth, and burrs on the edges and corners are removed.

[0064] Example 3

[0065] A method for preparing a SiC / SiC composite material for an aircraft engine hot end component comprises the following steps:

[0066] (1) SiC fibers were bundled in 6×6 bundles / cm 2 , 7×7 bundles / cm 2 and 8×8 bundles / cm 2 The weaving density is woven into three kinds of two-dimensional plain fiber cloths; the elements contained in the SiC fiber are Si, C, O and Al, the average diameter is 10μm, the fiber tow is 1600, and the density is 3.1g / cm 3 , the atomic ratio of C / Si is 0.92-0.95, the tensile strength is 2.4GPa, the breaking strain is 0.7%, and the temperature resistance is 1800℃; the average thickness of the two-dimensional plain fiber cloth is 0.2-0.3mm;

[0067] (2) The two-dimensional plain fiber cloth obtained in step (1) was woven into a 8×8 bundle / cm 2 -7×7 bundles / cm 2 -6×6 bundles / cm 2 -7×7 bundles / cm 2 -8×8 bundles / cm 2 The layers are laid sequentially, with three layers of each weaving density stacked together to form a total of 15 layers of fiber laminated cloth; then the preform is clamped by a graphite fixture and continuously needled to obtain a SiC fiber preform with a density gradient; during the continuous needle punching, the needle punching direction is perpendicular to the plane of the fiber cloth, and the number of needle punches per unit area is 10 needles / cm 2 The average thickness of the SiC fiber preform with density gradient is 3.4 mm.

[0068] (3) placing the SiC fiber preform with a density gradient obtained in step (2) into a boron nitride deposition furnace, and depositing a BN interface layer on the surface to obtain a fiber preform with a BN interface layer deposited thereon; during the BN interface layer deposition, argon was used as a protective gas, hydrogen was used as a carrier gas, ammonia and boron trichloride gas were introduced at a temperature of 1000° C., the ventilation rates were 0.25 L / min and 0.15 L / min, respectively, and the deposition time was 120 h; the average thickness of the BN interface layer was 500 nm;

[0069] (4) placing the fiber preform with the BN interface layer deposited in step (3) into a SiC vapor deposition furnace to perform SiC chemical vapor deposition to obtain a semi-densified SiC / SiC composite; the average density of the semi-densified SiC / SiC composite is 2.4 g / cm 3 ;

[0070] (5) The semi-densified SiC / SiC composite obtained in step (4) is separated from the graphite fixture, immersed in an epoxy resin impregnation solution at a pressure of -0.1 MPa, maintained for 0.5 h, and then taken out, and then dried and cured at a constant temperature of 80°C for 2 h, and the impregnation and curing steps are repeated until the weight gain rate is 10%, thereby obtaining a SiC / SiC composite with thermosetting resin infiltrated in the center; the epoxy resin impregnation solution is prepared by the following method: epoxy resin, diethylenetriamine, acetone and xylene are mixed in a mass ratio of 12:1:7:10, magnetically stirred, and ultrasonically dispersed for 0.5-1 h to obtain the epoxy resin impregnation solution;

[0071] (6) The SiC / SiC composite obtained in step (5) and infiltrated with a thermosetting resin at its center is immersed in an organic precursor solution at a pressure of -0.1 MPa and maintained for 0.5 h. The immersion step is repeated until the weight gain is 22%, and then cured at 150°C for 2 h. The SiC / SiC composite is then heated to 500°C at a heating rate of 10°C / min in an argon atmosphere and maintained for 5 h. Finally, the SiC / SiC composite is heated to 1200°C at a heating rate of 5°C / min to obtain a SiC / SiC composite having a void structure. The organic precursor solution is at least one of polycarbosilane, polymethylsilane and polypropylene hydroxycarbosilane. The average density of the SiC / SiC composite having a void structure is 2.9 g / cm 3 ;

[0072] (7) The SiC / SiC composite material with a void structure obtained in step (6) is post-treated, oxidized in a muffle furnace at 700° C. for 5 h, cooled to room temperature, cleaned and dried to obtain a SiC / SiC composite material for an aircraft engine hot end component; during post-treatment, dust on the composite material surface is removed, the surface is polished until it is smooth, and burrs on the edges and corners are removed.

[0073] Test example

[0074] The actual image of the SiC / SiC composite material for the hot end component of the aviation engine obtained in Example 2 is as follows: Figure 1 Its basic information and mechanical properties are shown in Table 1; the CT schematic diagram of its cross section is shown in Figure 2 As shown, the schematic diagram of SiC matrix after the ceramic precursor is cracked is as follows Figure 3 As shown. Among them, Figure 2 In the figure, the gray part is the fiber and matrix area at the cross section, and the black part is the void area inside the composite.

[0075] Table 1 Basic information and mechanical properties

[0076]

[0077]

[0078] Depend on Figure 1It can be seen that the SiC / SiC composite material for the hot end component of the aviation engine prepared in the present invention is well formed, has a smooth surface and a uniform SiC matrix, and can be machined into any desired plate shape.

[0079] Depend on Figure 2 It can be seen that the void structure of the SiC / SiC composite for the hot end component of an aircraft engine produced by the present invention is mainly concentrated in the central area inside the composite; the fiber density in this area is relatively low, and the epoxy resin can more effectively fill this area during the impregnation and curing process, so that the center of the interior of the final composite has a uniform void structure.

[0080] Depend on Figure 3 It can be seen that the PIP process adopted in the present invention can effectively fill the open pores between fibers after the epoxy resin impregnation and curing process is completed, can quickly achieve densification, and shorten the preparation cycle.

[0081] As shown in Table 1, the SiC / SiC composite for aircraft engine hot end components produced by the present invention maintains a relatively low density and a void structure while still exhibiting excellent tensile and flexural strength. Furthermore, the void-structured composite produced by the present invention exhibits a low coefficient of thermal expansion and significantly lower thermal conductivity in the Z direction than in the XY direction, demonstrating significant thermal insulation performance.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing SiC / SiC composites for hot end components of aircraft engines, characterized in that: The following steps are involved: (1) SiC fibers were bundled in 6×6 bundles / cm 2 , 7×7 bundles / cm 2 and 8×8 bundles / cm 2 The weaving density is woven into three kinds of two-dimensional plain fiber cloths; (2) The two-dimensional plain fiber cloth obtained in step (1) was woven into a 8×8 bundle / cm 2 -7×7 bundles / cm 2 -6×6 bundles / cm 2 -7×7 bundles / cm 2 -8×8 bundles / cm 2 The layers are laid sequentially, then clamped by a graphite fixture and continuously needled to obtain a SiC fiber preform with a density gradient; (3) placing the SiC fiber preform with a density gradient obtained in step (2) into a boron nitride deposition furnace, and depositing a BN interface layer on the surface to obtain a fiber preform with a deposited BN interface layer; (4) placing the fiber preform deposited with the BN interface layer obtained in step (3) into a SiC vapor deposition furnace to perform SiC chemical vapor deposition to obtain a semi-densified SiC / SiC composite; (5) The semi-densified SiC / SiC composite obtained in step (4) is separated from the graphite fixture and immersed in an epoxy resin impregnation solution at a pressure of -0.1 MPa, maintained for 0.5-0.6 hours, and then taken out and dried and cured at a constant temperature of 80°C for 2-3 hours. The impregnation and curing steps are repeated until the weight gain is 5-10%, thereby obtaining a SiC / SiC composite with thermosetting resin infiltrated in the center; (6) immersing the SiC / SiC composite obtained in step (5) with the thermosetting resin infiltrated at the center into an organic precursor solution at a pressure of -0.1 MPa for 0.5-0.6 h, repeating the immersion step until the weight gain is 18-22%, and then curing at a temperature of 120-150° C. for 2-3 h, and then heating to 500° C. at a heating rate of 1-10° C. / min in an argon atmosphere and holding for 5 h, and finally heating to 1200° C. at a heating rate of 5° C. / min to obtain a SiC / SiC composite with a void structure; (7) The SiC / SiC composite material with a void structure obtained in step (6) is post-treated and oxidized in a muffle furnace at 700° C. for 5-6 hours, cooled to room temperature, cleaned and dried to obtain a SiC / SiC composite material for hot end components of an aircraft engine.

2. The method for preparing a SiC / SiC composite material for an aircraft engine hot end component according to claim 1, wherein: In step (1), the SiC fibers contain Si, C, O, and Al, have an average diameter of 10 μm, have 1,600 fibers, and a density of 3-3.2 g / cm 3 , the atomic ratio of C / Si is 0.92-0.95, the tensile strength is 2.4Gpa, the fracture strain is 0.7%, and the temperature resistance is 1800℃.

3. The method for preparing a SiC / SiC composite material for an aircraft engine hot end component according to claim 1, wherein: In step (2), three layers of each weaving density are stacked to form a total of 15 layers of fiber laminated cloth.

4. The method for preparing a SiC / SiC composite material for an aircraft engine hot end component according to claim 1, wherein: In step (2), when the whole is continuously needled, the needle-punching direction is perpendicular to the plane where the fiber cloth is located, and the number of needle-punching processes is the number of needles per unit area, and the number of needles per cm is 5-10 needles / cm. 2 .

5. The method for preparing a SiC / SiC composite material for an aircraft engine hot end component according to claim 1, wherein: In step (3), when the BN interface layer is deposited, argon is used as the protective gas and hydrogen is used as the carrier gas. Ammonia and boron trichloride gases are introduced at a temperature of 1000°C, with ventilation rates of 0.25L / min and 0.15L / min, respectively, and the deposition time is 10-20h.

6. The method for preparing a SiC / SiC composite material for an aircraft engine hot end component according to claim 1, wherein: In step (5), the epoxy resin impregnation liquid is prepared by the following method: epoxy resin, diethylenetriamine, acetone and xylene are mixed in a mass ratio of 12:1:7:10, magnetically stirred, and ultrasonically dispersed for 0.5-1h to obtain the epoxy resin impregnation liquid.

7. The method for preparing a SiC / SiC composite material for an aircraft engine hot end component according to claim 1, wherein: In step (6), the organic precursor solution is at least one of polycarbosilane, polymethylsilane and polypropylene hydroxycarbosilane.

8. The method for preparing a SiC / SiC composite material for an aircraft engine hot end component according to claim 1, wherein: In step (6), the average density of the SiC / SiC composite with a void structure is 2.5-2.9 g / cm 3 .

9. The method for preparing a SiC / SiC composite material for an aircraft engine hot end component according to claim 1, wherein: In step (7), during post-processing, dust on the surface of the composite material is removed, the surface is polished until it is smooth, and burrs on the edges and corners are removed.

10. The SiC / SiC composite for hot end components of an aircraft engine produced by the method for producing the SiC / SiC composite for hot end components of an aircraft engine according to any one of claims 1 to 9.

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