A high-density fiber-reinforced SiBCN ceramic matrix composite and its preparation method

Abstract

The present invention relates to a high-density fiber-reinforced SiBCN ceramic matrix composite material and a preparation method thereof. The preparation method of the high-density fiber-reinforced SiBCN ceramic matrix composite material includes: firstly, realizing the preliminary deposition of the SiBCN matrix in the fiber preform by chemical vapor infiltration method, and then successively adopting precursor infiltration and pyrolysis method and secondary chemical vapor infiltration method to realize the densification of the SiBCN matrix in the fiber preform, so as to obtain the high-density fiber-reinforced SiBCN ceramic matrix composite material.

Description

Technical Field

[0001] The present invention relates to a high-density fiber-reinforced SiBCN ceramic matrix composite material and a preparation method thereof, belonging to the field of composite material preparation. Background Art

[0002] As a high-temperature thermal structural material, since the SiBCN ceramic was reported in the 1990s of the last century, it has received extensive attention and research from more and more scholars due to its excellent high-temperature resistance (the temperature resistance is as high as 2000 ο °C), oxidation resistance, thermal shock resistance, and good thermochemical compatibility. However, due to the fatal defect of the large brittleness of the pure SiBCN ceramic, the further use of the ceramic phase is restricted. Combining fibers with the SiBCN ceramic matrix to prepare fiber-reinforced SiBCN-based composite materials is an ideal method, which not only overcomes the brittleness of the pure ceramic but also fully exerts the reinforcing and toughening effects of the fibers, and is an ideal high-temperature resistant material applied to the hot-end structural parts of aircraft.

[0003] At present, the relatively common method for preparing SiBCN ceramics inside the fiber preform is the precursor infiltration and pyrolysis method, which mainly involves impregnating the fiber preform with the organic precursor polyborosilazane multiple times and then heating it to a high temperature for heat treatment. A series of reactions such as dehydrogenation, cross-linking, and polymerization occur to the organic molecules in the precursor at high temperatures, and then amorphous SiBCN ceramics are obtained. However, there are three obvious defects in using the SiBCN ceramic precursor infiltration and pyrolysis method: one is that the precursor raw materials and organic solvents are relatively expensive and toxic; the second is that small molecules will continuously overflow during the pyrolysis process of the precursor, causing the matrix to crack and shrink, resulting in cracks. During the service process of the material, the oxygen-containing components in the environment will erode the internal fibers and matrix through the cracks; the third is that when preparing materials solely by the precursor infiltration and pyrolysis method, due to matrix cracking and volume shrinkage, the porosity of the material is prone to be relatively high. Chinese Patent No. 201710980481.0 discloses a dense C f / SiBCN ceramic matrix composites and their preparation methods disclose the preparation of pure SiBCN ceramic matrices by the PIP method. The porosity of the prepared materials is less than 10%, but the porosity of the prepared materials is basically between 9% and 10%, and the porosity of the materials is relatively high. In addition, it has not been reported whether this method is applicable to SiC fiber preforms, especially two-dimensional plain weave SiC fiber preforms, because when simply impregnating two-dimensional plain weave preforms by the PIP method, the materials cannot be effectively formed and are prone to delamination.The Chinese patent with the application number 202010798886.4 discloses a high-performance C / SiBCN composite material, its preparation method and application. The liquid SiBCN precursor is used as the impregnation liquid to densify the carbon fiber preform to obtain the high-performance C / SiBCN composite material. However, the invention does not disclose the density performance data of the material. The preparation method is still the single PIP method for impregnating the material. The material density is low and the porosity is high. At the same time, the fiber preform applicable to the invention is a two-dimensional laminated stitched carbon fiber preform, where the two-dimensional fabrics are stitched together by fibers, which is not applicable to the two-dimensional plain weave laminated preform in the present invention. Also, because the two-dimensional plain weave preform is simply impregnated by the PIP method, the material cannot be effectively formed and the material is prone to delamination; The Chinese patent with the application number 202110323658.6 discloses a SiBCN interface coating for SiC fiber-reinforced composite materials, its preparation method and application. However, this patent is applied as an interface phase rather than a matrix phase. The matrix phase is a SiC ceramic phase rather than a SiBCN ceramic phase. At the same time, the invention does not disclose any material density performance data; The Chinese patent with the application number 201810846950.4 discloses a preparation method of a SiC fiber-reinforced ceramic matrix composite material. However, the material preparation method is a material prepared by precursor molding combined with chemical vapor infiltration. The inside of the fiber preform is mainly a SiBCN-Ti precursor powder containing ZrB2. The prepared material is not a pure SiBCN matrix material and does not give any density data of the material prepared by the chemical vapor infiltration method alone. And this method is only applicable to 2.5D fiber woven and 3D braided preforms and is not applicable to two-dimensional preforms; The Chinese patent with the application number 201310178800.8 discloses a chemical vapor deposition method of Si-B-C-N amorphous ceramics. Using SiCH3Cl3 or SiCl4, BCl3, NH3 as precursors and H2 as the carrier gas and dilution gas, a SiBCN interface was successfully prepared on the carbon fiber surface. However, it does not give the material performance, density and other parameter performance data when using SiBCN as the matrix. According to the process parameter conditions mentioned in the patent, it is impossible to confirm whether the SiBCN matrix can be prepared, the density of the prepared matrix material, and the mechanical and oxidation resistance performance data of the material; The Chinese patent with the application number 201510041187.4 discloses a ceramic matrix composite material with a silane-modified SiBCN as the precursor and its preparation method. Using a SiBCN precursor, toluene and polysilyne as solvents to prepare the matrix to obtain a carbon fiber-reinforced SiBCN ceramic matrix composite material. However, the precursor also has a volume shrinkage problem during the preparation process. The high porosity of the material leads to insufficient oxidation resistance of the material. Summary of the Invention

[0004] In view of the current situation that the density of SiBCN matrix prepared by the PIP method is relatively low and the oxidation resistance is insufficient at the present stage, the present invention provides a high-density fiber-reinforced SiBCN ceramic matrix composite material and a preparation method thereof.

[0005] On the one hand, the present invention provides a preparation method of a high-density fiber-reinforced SiBCN ceramic matrix composite material, including: first, realizing the preliminary deposition of the SiBCN matrix in the fiber preform by chemical vapor infiltration method, and then successively adopting precursor infiltration and pyrolysis method and secondary chemical vapor infiltration method to realize the densification of the SiBCN matrix in the fiber preform, so as to obtain the high-density fiber-reinforced SiBCN ceramic matrix composite material.

[0006] In the present invention, the CVI+PIP+CVI method is used in combination to prepare the material. This method is not only applicable to carbon fiber preforms, but also applicable to SiC fiber preforms. The prepared fiber-reinforced SiBCN ceramic matrix composite material not only has a lower porosity and a higher density, but also has excellent high-temperature oxidation resistance. The properties of the prepared material can meet the requirements of engineering applications to a certain extent.

[0007] Preferably, the fiber preform includes a carbon fiber preform and a SiC fiber preform;

[0008] The carbon fiber preform includes a carbon fiber needle-punched preform, a carbon fiber two-dimensional cloth laminated preform or a carbon fiber two-dimensional cloth stitched preform; preferably, the carbon fiber is T300, T700 or M40;

[0009] The SiC fiber preform includes a SiC fiber cloth, a SiC fiber two-dimensional laminated preform, a SiC fiber two-dimensional stitched preform, a SiC fiber three-dimensional braided preform, a SiC fiber 2.5D braided preform.

[0010] Preferably, an interface phase layer is deposited on the surface of the fiber in the fiber preform; the interface phase layer includes a PyC interface phase layer, a BN interface phase layer, a multi-layer (PyC / SiC)m interface phase layer with alternating deposition of PyC and SiC, and a multi-layer (BN / SiC)n interface phase layer with alternating deposition of BN and SiC; where m≥1, n≥1; the total thickness of the interface phase layer is 50-5000nm.

[0011] Preferably, the parameters of the chemical vapor infiltration method include: using NH3 as the nitrogen source, BCl3 as the boron source, methyltrichlorosilane MTS as the silicon source and carbon source, H2 as the carrier gas, N2 and Ar as the dilution gases, introducing the precursor into the furnace, and depositing for 1-200h at 0.01-3KPa and 600-1000°C to obtain the first-stage SiBCN ceramic matrix composite material.

[0012] Also, preferably, the molar ratio of NH3 to BCl3 is 0.5 to 20; the molar ratio of BCl3 to MTS is 0.3 to 30; the molar ratio of N2 to BCl3 in the dilution gas is 5 to 25; the molar ratio of N2 to Ar is 0.5 to 10.

[0013] Preferably, the precursor used for preparing the SiBCN ceramic matrix by precursor infiltration pyrolysis (PIP) is polyborosilazane; the viscosity of the precursor is below 20 mPa·S; the radical initiator used for the precursor is a peroxy initiator or / and an azo initiator; the addition amount of the radical initiator is 0.1 to 5 wt% of the mass of polyborosilazane.

[0014] Preferably, the peroxy initiator is at least one of lauroyl peroxide and dicumyl peroxide; the azo initiator is 2,2'-azobis(2-methylbutyronitrile).

[0015] Preferably, the process for preparing the SiBCN ceramic matrix by precursor infiltration pyrolysis includes: impregnation, curing, and pyrolysis to obtain a second-stage SiBCN ceramic matrix composite.

[0016] The time of impregnation is 1 to 2 h, and the pressure of impregnation is 0 Pa to 5 MPa.

[0017] The temperature of curing is 50 to 200 °C, and the time of curing is 1 to 20 h.

[0018] The temperature of pyrolysis is 900 to 1400 °C, and the time of pyrolysis is 1 to 2 h.

[0019] The number of times of impregnation, curing, and pyrolysis is 3 to 10 times.

[0020] Preferably, the parameters of the secondary chemical vapor infiltration method include: using NH3 as the nitrogen source, BCl3 as the boron source, trichloromethylsilane (MTS) as the silicon source and carbon source, H2 as the carrier gas, N2 and Ar as the dilution gas, introducing the precursor into the furnace, and depositing at 0.01 to 3 kPa and 600 to 1000 °C for 5 to 200 h to obtain a third-stage SiBCN ceramic matrix composite.

[0021] Also, preferably, the molar ratio of NH3 to BCl3 is 0.5 to 20, the molar ratio of BCl3 to MTS is 0.05 to 5, the molar ratio of N2 to BCl3 in the dilution gas is 5 to 25, and the molar ratio of N2 to Ar is 0.5 to 10.

[0022] Preferably, chemical vapor infiltration is used to achieve the preliminary deposition of the SiBCN matrix to obtain a first-stage SiBCN ceramic matrix composite, and the porosity of the first-stage SiBCN ceramic matrix composite is controlled below 30%.

[0023] The deposition of the SiBCN matrix is achieved by the precursor infiltration and pyrolysis method to obtain the second-stage SiBCN ceramic matrix composite, and the porosity of the second-stage SiBCN ceramic matrix composite is controlled below 20%.

[0024] The deposition of the SiBCN matrix is achieved by the chemical vapor infiltration method to obtain the third-stage SiBCN ceramic matrix composite, and the porosity of the third-stage SiBCN ceramic matrix composite reaches below 6%.

[0025] On the other hand, the present invention provides a high-density fiber-reinforced SiBCN ceramic matrix composite prepared according to the above preparation method. The bending strength of the high-density fiber-reinforced SiBCN ceramic matrix composite is 200 - 550 MPa, and the porosity ≤ 6%.

[0026] Beneficial effects

[0027] (1) In the present invention, the SiBCN matrix is first prepared by the CVI method on the surface of the fiber preform with an interfacial phase modification. On the one hand, through the effective regulation of the precursor components, the effective regulation of the elemental content of each component of the CVI SiBCN matrix can be achieved. The existence of the CVI SiBCN matrix can effectively wrap the fibers in a ring shape to meet the requirements of different application environments. On the other hand, by using the CVI method for SiBCN deposition, the effective filling of the pores within the fiber bundle can be maximally achieved, thereby effectively protecting the single fibers within the fiber bundle and the interfacial phase outside the fibers, and then improving the material density. Finally, as the dense continuous ceramic phase, the CVI SiBCN matrix contacts with the interfacial phase, which can effectively increase the bonding strength between the interfacial phase and the matrix. The strengthening and toughening mechanisms such as interfacial debonding and fiber pull-out can be effectively exerted, thereby improving the mechanical properties of the material.

[0028] (2) The CVI method is used to prepare the SiBCN matrix for the first preliminary densification of the two-dimensional SiC fiber cloth laminated preform. After the CVI preliminary densification, the bonding strength between different layers of fiber cloths in the two-dimensional SiC fiber cloth laminated preform is greatly improved and successfully bonded together, avoiding the volume expansion caused by the subsequent PIP densification process, the phenomenon of material non-forming and delamination.

[0029] (3) Compared with the preparation of the SiBCN matrix material by first using the PIP method and then the CVI method, or only using a single CVI method or a single PIP method to prepare the SiBCN matrix material, by using the combination of the CVI method first, then the PIP method, and finally the CVI method in the present invention to prepare the SiBCN matrix, the porosity of the material can be significantly reduced and the density can be significantly improved.

[0030] (4) The outermost SiBCN matrix of the material is prepared by the CVI method, which can effectively seal the cracks and defects generated during the volume shrinkage in the process of preparing the matrix by the PIP method in the early stage, minimize the residual porosity inside the material to the greatest extent, and form a continuous dense protective layer on the surface of the fibers and the matrix throughout the material, thus playing a protective role similar to that of a coating for the material;

[0031] (5) The content of each elemental component in the outermost SiBCN matrix (such as the content of Si element in the matrix) can be selectively adjusted according to the requirements of the service environment of the material application, so that the outermost SiBCN matrix can play a good self-healing protection effect on the material. Description of the Drawings

[0032] Figure 1 It is the three-point bending displacement curve diagram of the carbon fiber reinforced SiBCN-based composite materials in Examples 1 and 2, where the abscissa is displacement (Displacement) / mm and the ordinate is flexural strength (Flexural strength) / MPa;

[0033] Figure 2 It is the three-point bending displacement curve diagram of the SiC fiber reinforced SiBCN-based composite material in Example 3, where the abscissa is displacement (Displacement) / mm and the ordinate is flexural strength (Flexural strength) / MPa;

[0034] Figure 3 It is the scanning electron micrograph of the polished sample of the carbon fiber reinforced SiBCN-based composite material in Example 1;

[0035] Figure 4 It is the scanning electron micrograph of the polished sample of the carbon fiber reinforced SiBCN-based composite material in Example 1;

[0036] Figure 5 In (a) is the physical diagram of the two-dimensional cloth laminated silicon carbide fiber reinforced SiBCN-based composite material prepared by the single CVI method in Comparative Example 1, (b) is the physical diagram of the two-dimensional cloth laminated silicon carbide fiber reinforced SiBCN-based composite material prepared by the CVI method first and then the PIP method in Comparative Example 2, and (c) is the physical diagram of the two-dimensional cloth laminated silicon carbide fiber reinforced SiBCN-based composite material prepared by the CVI+PIP+CVI method in Example 3 of the present invention;

[0037] Figure 6Figure (a) is a physical diagram of a carbon fiber reinforced SiBCN matrix composite prepared by a single CVI method in Comparative Example 4, (b) is a physical diagram of a carbon fiber reinforced SiBCN matrix composite prepared by first using the PIP method and then the CVI method in Comparative Example 5, and (c) is a physical diagram of a carbon fiber reinforced SiBCN matrix composite prepared by the CVI+PIP+CVI method in Example 1 of the present invention;

[0038] Figure 7 It is a scanning electron micrograph of a polished sample of a carbon fiber reinforced SiBCN matrix composite prepared by a single PIP method in Comparative Example 4 of the present invention. Detailed implementation mode

[0039] The present invention will be further described below through the following implementation modes. It should be understood that the following implementation modes are only used to illustrate the present invention and do not limit the present invention.

[0040] For existing fiber-reinforced ceramic matrix composites, when the porosity is reduced to a certain level, the difficulty coefficient of further reducing the porosity becomes higher. In view of the current situation that the density of the SiBCN matrix prepared by the PIP method is relatively low and the antioxidant property is insufficient, the present disclosure provides a method that can effectively regulate the matrix composition, content, etc., providing new research ideas and methods for the further development of fiber-reinforced ceramic matrix composites. Specifically, a certain mass fraction of SiBCN matrix is deposited on the surface of the fiber preform by low-pressure chemical vapor infiltration (CVI method), so that the SiBCN matrix on the fiber surface realizes a circular wrapping around the fiber. The precursor infiltration and pyrolysis method (PIP method) is used to impregnate-cure-pyrolyze the fiber preform with the liquid SiBCN precursor solution multiple times to achieve the preliminary densification of the fiber preform. After the sample is processed, the CVI method is continued to perform the final densification treatment on the material to obtain a high-density fiber-reinforced SiBCN ceramic matrix composite.

[0041] The suitable interface phase prepared by the present invention realizes the strengthening and toughening effect on the material; the combined use of the CVI and PIP methods effectively reduces the internal porosity of the material and improves the mechanical properties of the material; the circular wrapping of the SiBCN matrix prepared by CVI on the fiber realizes the effective protection of single fibers and the effective filling of pores in the fiber bundle, and as the last layer of matrix of the material, it can play a protective role similar to that of a coating on the material.

[0042] As an example, the specific preparation process of a high-density fiber-reinforced SiBCN matrix composite provided by the present invention is as follows.

[0043] Place the fiber preform into the furnace, perform a vacuum flushing operation, heat up to a specific temperature, and then introduce the interface phase deposition precursor into the furnace to obtain a modified fiber preform with an interface phase layer. The fiber preform includes a carbon fiber preform and a SiC fiber preform; the carbon fiber preform includes types such as a carbon fiber needled preform, a carbon fiber two-dimensional fabric laminated preform, and a carbon fiber two-dimensional fabric stitched preform; the carbon fiber types can be fiber types such as T300, T700, and M40. The SiC fiber preform includes types such as a SiC fiber cloth, a SiC fiber two-dimensional laminated preform, a SiC fiber two-dimensional stitched preform, a SiC fiber three-dimensional braided preform, and a SiC fiber 2.5D braided preform. The interface phase can be a PyC interface phase, a BN interface phase, a multi-layer (PyC / SiC)n interface phase with alternating deposition of PyC and SiC, a multi-layer (BN / SiC)n interface phase with alternating deposition of BN and SiC, etc.

[0044] After the interface phase deposition is completed, raise the temperature in the furnace to a specific temperature, hold for a period of time, and then introduce the SiBCN precursor (NH3, BCl3, CH3Cl3Si (trichloromethylsilane, MTS), H2, N2, and Ar), and deposit for a period of time under constant temperature and pressure to obtain a preliminary SiBCN matrix fiber preform. During the preparation of the SiBCN matrix, the molar ratio of NH3 to BCl3 is 0.5 - 20, the molar ratio of BCl3 to MTS is 0.3 - 30, the molar ratio of the dilution gas N2 to BCl3 is 5 - 25, and the molar ratio of N2 to Ar is 0.5 - 10. The reaction temperature of the SiBCN interface coating is 600 - 1000 ο °C, the deposition time is 1 - 200 hours, and the deposition pressure is 0.01 - 3 Kpa.

[0045] Immerse the preliminary CVI densified SiBCN matrix material in the SiBCN precursor solution, and use the PIP method to perform multiple impregnation-curing-pyrolysis process treatments on the material to obtain a dense material. The SiBCN ceramic precursor prepared by the PIP method is polyborosilazane, the viscosity of the precursor is below 20 mPa·S, and the radical initiator is one or more of peroxide initiators (lauroyl peroxide, diisopropylbenzene peroxide) and azo initiators (azodiisooctanenitrile). The impregnation time of the precursor in the SiBCN matrix prepared by the PIP method is 1 - 2 h; the curing temperature is 50 - 200 ο °C, the curing time is 1 - 20 h; the pyrolysis temperature is 900 - 1400 ο °C, the pyrolysis time is 1 - 2 h, and the number of impregnation-curing-pyrolysis times is 3 - 10 times.

[0046] After the sample is processed and cleaned, it is placed in a furnace for the final CVI SiBCN matrix densification treatment to obtain a high-density fiber-reinforced SiBCN ceramic matrix composite. During the preparation of the SiBCN matrix, the molar ratio of NH3 to BCl3 is 0.5 - 20, the molar ratio of BCl3 to MTS is 0.05 - 5, the molar ratio of the dilution gas N2 to BCl3 is 5 - 25, the molar ratio of N2 to Ar is 0.5 - 10, the reaction temperature is 600 - 1000 ο °C, the deposition pressure is 0.01 - 3 KPa, and the deposition time is 5 - 200 hours.

[0047] In the present invention, the chemical vapor infiltration method (CVI method) is first adopted, then the precursor infiltration and pyrolysis method (PIP method) is adopted, and finally the chemical vapor infiltration method (CVI method) is adopted again for final densification. Compared with the traditional method of ending with CVI and then conducting multiple PIP densification to complete the material preparation or simply using the PIP method to prepare the material, the material density is significantly improved.

[0048] More specifically, as an example, the specific process of a high-density fiber-reinforced SiBCN ceramic matrix composite provided by the present invention is as follows:

[0049] (1) Place the carbon fiber preform (e.g., carbon fiber needle-punched preform, carbon fiber two-dimensional cloth laminated preform, carbon fiber two-dimensional cloth stitched preform) or SiC fiber preform (e.g., SiC fiber cloth, SiC fiber two-dimensional laminated preform, SiC fiber two-dimensional stitched preform, SiC fiber three-dimensional braided preform, SiC fiber 2.5D braided preform) into the furnace, perform the vacuum flushing operation 2 - 3 times, heat up to a specific temperature (e.g., 900 - 1100 ο °C), and then introduce the interface phase deposition precursor into the furnace to obtain a fiber preform with modified interface phase.

[0050] (2) After the interface phase deposition is completed, raise the temperature in the furnace to a specific temperature, keep it for a period of time, then use NH3 as the nitrogen source, BCl3 as the boron source, CH3Cl3Si (trichloromethylsilane, MTS) as the silicon source and carbon source, H2 as the dilution gas and carrier gas, and N2 and Ar as the dilution gases. Introduce the above precursors into the furnace, where the molar ratio of NH3 to BCl3 is 0.5 - 20, the molar ratio of BCl3 to MTS is 0.3 - 30, the molar ratio of the dilution gas N2 to BCl3 is 5 - 25, the molar ratio of N2 to Ar is 0.5 - 10, and deposit for a period of time (e.g., 1 - 200 h) at a constant pressure (e.g., 0.01 - 3 KPa) and a constant temperature (e.g., 600 - 1000 ο °C) to obtain a fiber preform preliminarily containing the SiBCN matrix.

[0051] (3) The preliminarily CVI densified SiBCN matrix material is impregnated with SiBCN precursor solution and free radical initiator, and the material is processed by multiple impregnation-curing-pyrolysis procedures using the PIP method to obtain a dense material. Among them, the precursor solution is a SiBCN ceramic precursor (such as polyborosilazane), and the free radical initiator includes peroxide initiators (such as lauroyl peroxide, dicumyl peroxide) and / or azo initiators (such as 2,2'-azobis(2-methylbutyronitrile)); the precursor impregnation time is 1 - 2 h; the curing temperature is 50 - 200 ο °C, the curing time is 1 - 20 h; the pyrolysis temperature is 900 - 1400 ο °C, the pyrolysis time is 1 - 2 h, and the number of impregnation-curing-pyrolysis is 3 - 10 times;

[0052] (4) After the sample is processed and cleaned, it is placed in a furnace for the final CVI densification treatment of the SiBCN matrix to obtain a high-density fiber-reinforced SiBCN ceramic matrix composite. Among them, the SiBCN deposition precursors and dilution gases are NH3, BCl3, MTS, H2, N2, and Ar. The molar ratio of NH3 to BCl3 is 0.5 - 20, the molar ratio of BCl3 to MTS is 0.05 - 5, the molar ratio of the dilution gas N2 to BCl3 is 5 - 25, and the molar ratio of N2 to Ar is 0.5 - 10. It is deposited for a period of time (such as 5 - 200 hours) at a constant temperature (such as 600 - 1000 ο °C) and a constant pressure (such as 0.01 - 3 KPa).

[0053] In the present invention, the porosity of the final fiber-reinforced SiBCN ceramic matrix composite measured by the Archimedes drainage method is ≤6%, and the flexural strength of the fiber-reinforced SiBCN ceramic matrix composite measured by the three-point bending strength test method of the composite material is 200 - 550 MPa.

[0054] The following further gives examples to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the protection scope of the present invention. The specific process parameters and the like in the following examples are also only an example within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description herein, rather than being limited to the specific values in the following examples.

[0055] Example 1:

[0056] A preparation method and material properties of a carbon fiber-reinforced SiBCN-based composite material of model C-1, the material porosity is 5.66%, the material flexural strength is 468.6 MPa, and the material stress-displacement curve is shown inFigure 1 As shown, the specific preparation steps include:

[0057] (1) Cut the T700 carbon fiber needle-punched preform into a size of 50×100 mm. Place the specimen in the reaction chamber of the furnace, perform the vacuum flushing operation twice, and raise the temperature to 500 ο °C at a rate of 8 °C per minute under vacuum. After holding for half an hour, raise the temperature to 1000 ο °C at a rate of 5 °C per minute. After the temperature is reached, hold for half an hour;

[0058] (2) Using methane as the precursor, Ar as the diluent gas, the molar ratio of Ar to methane is 20, the deposition temperature is 1000 ο °C, the deposition pressure is 3 KPa, and the deposition time is 10 hours to complete the preparation of the PyC interface phase on the fiber surface;

[0059] (3) Using trichloromethylsilane (MTS) as the silicon source, NH3 as the nitrogen source, BCl3 as the boron source, H2 as the carrier gas, N2 and Ar as the diluent gases, the molar ratio of NH3 to BCl3 is 10:1, the molar ratio of BCl3 to MTS is 3, the molar ratio of the diluent gas N2 to BCl3 is 10, the molar ratio of N2 to Ar is 5, and the deposition temperature of the SiBCN matrix is 800 ο °C, the deposition time is 20 hours, and the deposition pressure is 0.1 KPa;

[0060] (4) Place the preform with the deposited SiBCN matrix into the impregnation tank, and use polyborosilazane and dicumyl peroxide as the precursors to densify the fiber preform. The impregnation time of the precursor is 1.5 h; the curing temperature is 100 ο °C, the curing time is 15 h; the pyrolysis temperature is 950 ο °C, the pyrolysis time is 1.5 h, and the number of impregnation-curing-pyrolysis times is 5 times;

[0061] (5) After cleaning the sample densified by PIP, place it in the furnace for the final CVI SiBCN matrix densification treatment to obtain a high-density carbon fiber reinforced SiBCN ceramic matrix composite. Among them, the molar ratio of NH3 to BCl3 is 10, the molar ratio of BCl3 to MTS is 0.5, the molar ratio of the diluent gas N2 to BCl3 is 10, the molar ratio of N2 to Ar is 5, the deposition temperature of the SiBCN matrix is 800 ο °C, the deposition time is 40 hours, and the deposition pressure is 0.5 KPa.

[0062] Example 2:

[0063] Preparation method and material properties of a carbon fiber reinforced SiBCN matrix composite with model C-2. The porosity of the material is 5.89%, the flexural strength of the material is 458.7 MPa, and the stress-displacement curve of the material is shown in Figure 1 as follows. The specific preparation steps include:

[0064] (1) Cut the T700 carbon fiber needle-punched preform into a size of 50×100 mm. Place the sample in the reaction chamber of the furnace, perform the vacuum flushing operation twice, and raise the temperature to 500 ο °C at a rate of 8 °C per minute under vacuum. After holding for half an hour, raise the temperature to 1000 ο °C at a rate of 5 °C per minute. After the temperature rises, hold for half an hour;

[0065] (2) For PyC interface deposition, use methane as the precursor and Ar as the dilution gas. The molar ratio of Ar to methane is 20, and the deposition temperature is 1000 ο °C, and the deposition pressure is 3 KPa; for SiC deposition, use trichloromethylsilane (MTS) as the silicon source, H2 as the carrier gas and dilution gas, Ar as the dilution gas, and the molar ratio of hydrogen to MTS is 10. The deposition temperature is 980 ο °C to complete the preparation of the (PyC / SiC)3 interface phase on the fiber surface;

[0066] (3) Using trichloromethylsilane (MTS) as the silicon source, NH3 as the nitrogen source, BCl3 as the boron source, H2 as the carrier gas, N2 and Ar as the dilution gases. The molar ratio of NH3 to BCl3 is 10:1, the molar ratio of BCl3 to MTS is 3, the molar ratio of the dilution gas N2 to BCl3 is 10, the molar ratio of N2 to Ar is 5, and the deposition temperature of the SiBCN matrix is 800 ο °C, the deposition time is 40 hours, and the deposition pressure is 0.1 KPa;

[0067] (4) Place the preform deposited with the SiBCN matrix into an impregnation tank, and use polyborosilazane and dicumyl peroxide as the precursors to densify the fiber preform. The impregnation time of the precursor is 1.5 h; the curing temperature is 100 ο °C, the curing time is 15 h; the pyrolysis temperature is 950 ο °C, the pyrolysis time is 1.5 h, and the number of impregnation-curing-pyrolysis times is 6 times;

[0068] (5) Wash the sample after PIP densification and then put it into the furnace for the final CVI SiBCN matrix densification treatment to obtain a high-density carbon fiber reinforced SiBCN ceramic matrix composite. Among them, the molar ratio of NH3 to BCl3 is 10, the molar ratio of BCl3 to MTS is 0.5, the molar ratio of the dilution gas N2 to BCl3 is 10, the molar ratio of N2 to Ar is 5, and the deposition temperature of the SiBCN matrix is 800ο C, the deposition time is 60 hours, and the deposition pressure is 0.5 KPa.

[0069] Example 3:

[0070] A preparation method and material properties of a carbon fiber reinforced SiBCN - based composite material of model SiC - 1. The porosity of the material is 5.91%, the flexural strength of the material is 280.8 MPa, and the stress - displacement curve of the material is shown in Figure 2 as follows. The specific preparation steps include:

[0071] (1) Cut the two - dimensional laminated fabric of SiC fibers into a size of 65×80 mm. After fixing the cut two - dimensional laminated preform with a fixture, place it in the reaction chamber of the furnace, perform the vacuum flushing operation 2 times, and raise the temperature to 500 ο C at a rate of 8 °C / minute under vacuum state. After holding for half an hour, raise the temperature to 850 ο C at a rate of 5 °C / minute. After the temperature rises, hold for half an hour;

[0072] (2) Using NH3 as the nitrogen source, BCl3 as the boron source, H2 as the carrier gas, with the molar ratio of NH3 and BCl3 being 10:1, the deposition temperature is 880 ο C to complete the preparation of the BN interfacial phase on the fiber surface;

[0073] (3) Using trichloromethylsilane (MTS) as the silicon source, NH3 as the nitrogen source, BCl3 as the boron source, H2 as the carrier gas, N2 and Ar as dilution gases, with the molar ratio of NH3 and BCl3 being 10:1, the molar ratio of BCl3 and MTS being 3, the molar ratio of the dilution gas N2 and BCl3 being 10, the molar ratio of N2 and Ar being 5, the deposition temperature of the SiBCN matrix is 800 ο C, the deposition time is 50 hours, and the deposition pressure is 0.1 KPa;

[0074] (4) Put the preform with the deposited SiBCN matrix into an impregnation tank, and use polyborosilazane and dicumyl peroxide as precursors to densify the fiber preform. The impregnation time of the precursor is 1.5 h; the curing temperature is 100 ο C, the curing time is 15 h; the pyrolysis temperature is 950 ο C, the pyrolysis time is 1.5 h, and the number of impregnation - curing - pyrolysis times is 5 times;

[0075] (5) After densifying the PIP samples, they were cleaned and then placed in a furnace for the final CVI SiBCN matrix densification treatment to obtain a high-density silicon carbide fiber-reinforced SiBCN ceramic matrix composite. Among them, the molar ratio of NH3 to BCl3 was 10, the molar ratio of BCl3 to MTS was 0.5, the molar ratio of the dilution gas N2 to BCl3 was 10, the molar ratio of N2 to Ar was 5, and the deposition temperature of the SiBCN matrix was 800 ο °C, the deposition time was 60 hours, and the deposition pressure was 0.5 KPa.

[0076] Comparative Example 1:

[0077] A preparation method and material properties of a silicon carbide fiber-reinforced SiBCN matrix composite prepared by a single CVI method with the model number SiC-2. The porosity of the material was 11.25%, the flexural strength of the material was 245.3 MPa, and the stress-displacement curve of the material is shown in Figure 2 as follows. The specific preparation steps include:

[0078] (1) Cut the two-dimensional laminated cloth of SiC fibers into a size of 65×80 mm. After fixing the cut two-dimensional laminated preform with a fixture, place it in the reaction chamber of the furnace, perform the vacuum flushing operation 2 times, and heat it to 500 ο °C at a rate of 8 °C / minute under vacuum. After holding for half an hour, heat it to 850 ο °C at a rate of 5 °C / minute. After the temperature rises, hold for half an hour;

[0079] (2) Using NH3 as the nitrogen source, BCl3 as the boron source, H2 as the carrier gas, with the molar ratio of NH3 to BCl3 being 10:1 and the deposition temperature being 880 ο °C, complete the preparation of the BN interface phase on the fiber surface;

[0080] (3) Using trichloromethylsilane (MTS) as the silicon source, NH3 as the nitrogen source, BCl3 as the boron source, H2 as the carrier gas, N2 and Ar as the dilution gases, with the molar ratio of NH3 to BCl3 being 10:1, the molar ratio of BCl3 to MTS being 3, the molar ratio of the dilution gas N2 to BCl3 being 10, the molar ratio of N2 to Ar being 5, and the deposition temperature of the SiBCN matrix being 800 ο °C, the deposition time was 150 hours, and the deposition pressure was 0.1 Kpa to obtain a silicon carbide fiber-reinforced SiBCN matrix composite.

[0081] Comparative Example 2

[0082] A preparation method and material properties of a silicon carbide fiber-reinforced SiBCN matrix composite prepared by combining the CVI method and the PIP method with the model number SiC-3. The porosity of the material was 8.51%, the flexural strength of the material was 259.1 MPa, and the stress-displacement curve of the material is shown inFigure 2 As shown in the figure, the specific preparation steps are as follows:

[0083] (1) Cut the two-dimensional laminated cloth of SiC fibers into a size of 65×80 mm. After fixing the cut two-dimensional laminated preform with a fixture, place it in the reaction chamber of the furnace, perform the vacuum flushing operation twice, and raise the temperature to 500 ο °C at a rate of 8 °C per minute under vacuum. After holding for half an hour, raise the temperature to 850 ο °C at a rate of 5 °C per minute. After the temperature rises, hold for half an hour;

[0084] (2) Using NH3 as the nitrogen source, BCl3 as the boron source, H2 as the carrier gas, with a molar ratio of NH3 to BCl3 of 10:1 and a deposition temperature of 880 ο °C, complete the preparation of the BN interfacial phase on the fiber surface;

[0085] (3) Using trichloromethylsilane (MTS) as the silicon source, NH3 as the nitrogen source, BCl3 as the boron source, H2 as the carrier gas, N2 and Ar as dilution gases, with a molar ratio of NH3 to BCl3 of 10:1, a molar ratio of BCl3 to MTS of 3, a molar ratio of dilution gas N2 to BCl3 of 10, a molar ratio of N2 to Ar of 5, and a deposition temperature of the SiBCN matrix of 800 ο °C, a deposition time of 50 hours, and a deposition pressure of 0.1 KPa;

[0086] (4) Place the preform deposited with the SiBCN matrix into an impregnation tank, and use polyborosilazane and dicumyl peroxide as the precursors to densify the fiber preform. The impregnation time of the precursor is 1.5 h; the curing temperature is 100 ο °C, the curing time is 15 h; the pyrolysis temperature is 950 ο °C, the pyrolysis time is 1.5 h, and the number of impregnation-curing-pyrolysis is 5 times to obtain the SiC fiber reinforced SiBCN matrix composite material.

[0087] Comparative Example 3

[0088] A preparation method and material properties of a two-dimensional cloth laminated reinforced SiBCN matrix composite material of silicon carbide fiber of model SiC-3 prepared only by the single PIP method. After the material is densified by PIP, delamination occurs and effective performance data cannot be obtained. The specific preparation steps are as follows:

[0089] (1) Cut the two-dimensional laminated cloth of SiC fibers into a size of 65×80 mm. After fixing the cut two-dimensional laminated preform with a fixture, place it in the reaction chamber of the furnace, perform the vacuum flushing operation twice, and raise the temperature to 500 ο °C at a rate of 8 °C per minute under vacuum. After holding for half an hour, raise the temperature to 850 οC. Keep the temperature for half an hour after it rises to the set value.

[0090] (2) Using NH3 as the nitrogen source, BCl3 as the boron source, and H2 as the carrier gas, with the molar ratio of NH3 to BCl3 being 10:1, the deposition temperature is 880 ο C to complete the preparation of the BN interfacial phase on the fiber surface.

[0091] (3) Put the preform after depositing the BN interface into the impregnation tank, and use polyborosilazane and dicumyl peroxide as the precursors to densify the fiber preform. The impregnation time of the precursors is 1.5 h; the curing temperature is 100 ο C, the curing time is 15 h; the pyrolysis temperature is 950 ο C, the pyrolysis time is 1.5 h, and the number of impregnation-curing-pyrolysis cycles is 5 times to obtain the SiC fiber reinforced SiBCN matrix composite.

[0092] Comparative Example 4

[0093] A preparation method and material properties of a carbon fiber reinforced SiBCN matrix composite prepared only by the single PIP method with the model number C-3. The porosity of the material is 9.81%, the flexural strength of the material is 303.2 MPa, and the stress-displacement curve of the material is shown in Figure 1 as follows. The specific preparation steps include:

[0094] (1) Cut the T700 carbon fiber needle-punched preform into a size of 50×100 mm, place the specimen in the reaction chamber of the furnace, perform the vacuum flushing operation 2 times, and raise the temperature to 500 at a rate of 8 °C per minute under vacuum ο C, keep the temperature for half an hour and then raise it to 1000 at a rate of 5 °C per minute ο C. Keep the temperature for half an hour after it rises to the set value.

[0095] (2) Using methane as the precursor and Ar as the diluent gas, with the molar ratio of Ar to methane being 20, the deposition temperature is 1000 ο C, the deposition pressure is 3 KPa, and the deposition time is 10 hours to complete the preparation of the PyC interfacial phase on the fiber surface.

[0096] (3) Put the preform with the deposited PyC interface into the impregnation tank, and use polyborosilazane and dicumyl peroxide as the precursors to densify the fiber preform. The impregnation time of the precursors is 1.5 h; the curing temperature is 100 ο C, the curing time is 15 h; the pyrolysis temperature is 950 ο C, the pyrolysis time is 1.5 h, and the number of impregnation-curing-pyrolysis cycles is 5 times to obtain the carbon fiber reinforced SiBCN matrix composite.

[0097] Comparative Example 5

[0098] Preparation method and material properties of a carbon fiber reinforced SiBCN matrix composite prepared by PIP method first and then CVI method with model C-4. The porosity of the material is 8.91%, the flexural strength of the material is 411.0 MPa, and the stress-displacement curve of the material is shown in Figure 1 the following figure. The specific preparation steps are as follows:

[0099] (1) Cut the T700 carbon fiber needle-punched preform into a size of 50×100 mm. Place the specimen in the reaction chamber of the furnace, perform the vacuum flushing operation twice, and heat it to 500 ο °C at a rate of 8 °C per minute under vacuum. After holding for half an hour, heat it to 1000 ο °C at a rate of 5 °C per minute. After the temperature rises, hold for half an hour;

[0100] (2) Use methane as the precursor and Ar as the diluent gas. The molar ratio of Ar to methane is 20. The deposition temperature is 1000 ο °C, the deposition pressure is 3 KPa, and the deposition time is 10 hours to complete the preparation of the PyC interface phase on the fiber surface;

[0101] (3) Put the preform with the deposited PyC interface phase into the impregnation tank, and use polyborosilazane and dicumyl peroxide as the precursors to densify the fiber preform. The impregnation time of the precursor is 1.5 h; the curing temperature is 100 ο °C, the curing time is 15 h; the pyrolysis temperature is 950 ο °C, the pyrolysis time is 1.5 h, and the number of impregnation-curing-pyrolysis is 5 times;

[0102] (4) Clean the sample after PIP densification and then put it into the furnace for the final CVI SiBCN matrix densification treatment to obtain a high-density carbon fiber reinforced SiBCN ceramic matrix composite. Among them, the molar ratio of NH3 to BCl3 is 10, the molar ratio of BCl3 to MTS is 0.5, the molar ratio of the diluent gas N2 to BCl3 is 10, the molar ratio of N2 to Ar is 5, the deposition temperature of the SiBCN matrix is 800 ο °C, the deposition time is 40 hours, and the deposition pressure is 0.5 KPa.

[0103] Figure 1 Figure of the three-point bending displacement curve of the carbon fiber reinforced SiBCN matrix composite in Examples 1 and 2. It can be seen from the figure that the material shows obvious non-brittle fracture characteristics.

[0104] Figure 2 Figure of the three-point bending displacement curve of the SiC fiber reinforced SiBCN matrix composite in Example 3. It can be seen from the figure that the material shows obvious non-brittle fracture characteristics.

[0105] Figure 3 It is a scanning electron micrograph of the polished sample of the carbon fiber reinforced SiBCN-based composite material in Example 1. It can be seen from the figure that the matrix inside the material is very dense.

[0106] Figure 4 It is a scanning electron micrograph of the polished sample of the carbon fiber reinforced SiBCN-based composite material in Example 1. It can be seen from the figure that the outermost SiBCN matrix has successfully penetrated into the internal residual pores of the material and effectively filled them, further improving the material density.

[0107] Figure 5 In (a), it is a physical picture of the two-dimensional cloth laminated silicon carbide fiber reinforced SiBCN-based composite material prepared by the single CVI method in Comparative Example 1. In (b), it is a physical picture of the two-dimensional cloth laminated silicon carbide fiber reinforced SiBCN-based composite material prepared by the CVI method first and then the PIP method in Comparative Example 2. In (c), it is a physical picture of the two-dimensional cloth laminated silicon carbide fiber reinforced SiBCN-based composite material prepared by the CVI+PIP+CVI method in Example 3 of the present invention. It can be seen from Figure (a) that there are a large number of pores on the surface of the material prepared by the single CVI method. It can be seen from Figure (b) that the large pores on the surface of the material prepared by the CVI and PIP methods disappear, but there are still a small number of pores. It can be seen from Figure (c) that almost no pores can be seen on the surface of the material prepared by the CVI+PIP+CVI method of the present invention, and the material is very dense.

[0108] Figure 6 In (a), it is a physical picture of the carbon fiber reinforced SiBCN-based composite material prepared by the single CVI method in Comparative Example 4. In (b), it is a physical picture of the carbon fiber reinforced SiBCN-based composite material prepared by the PIP method first and then the CVI method in Comparative Example 5. In (c), it is a physical picture of the carbon fiber reinforced SiBCN-based composite material prepared by the CVI+PIP+CVI method in Example 1 of the present invention. It can be seen from Figure (a) that there are obvious large pores on the surface of the material prepared by the single CVI method. It can be seen from Figure (b) that the large pores on the surface of the material prepared by the PIP and CVI methods disappear, but there are still a small number of pores. It can be seen from Figure (c) that the surface of the material prepared by the CVI+PIP+CVI method of the present invention is very dense and almost no pores can be seen.

[0109] Figure 7 It is a scanning electron micrograph of the polished sample of the carbon fiber reinforced SiBCN-based composite material prepared by the single PIP method in Comparative Example 4 of the present invention. It can be seen from the figure that there are large pores inside the material due to volume shrinkage during the PIP preparation process, and the porosity is relatively high.

[0110] Table 1 shows the flexural strength performance data of the SiC f / SiBCN composite material prepared by the CVI+PIP+CVI method of the present invention after 1000 ο C water oxygen for 20h:

[0111]

[0112] It can be seen from Table 1 that the strength retention rate of the material after oxidation test is as high as over 90%, and the material exhibits excellent high-temperature oxidation resistance.

Claims

1. A preparation method of a high-density fiber-reinforced SiBCN ceramic matrix composite material, characterized in that, Including: The first-stage SiBCN ceramic matrix composite is obtained by initially depositing the SiBCN matrix in the fiber preform using chemical vapor infiltration. The parameters of the chemical vapor infiltration method include: using NH3 as the nitrogen source, BCl3 as the boron source, trichloromethylsilane (MTS) as the silicon and carbon source, H2 as the carrier gas, and N2 and Ar as the dilution gases. The precursor is introduced into the furnace and deposited at 0.01 - 0.1 KPa and 600 - 1000 °C for 20 - 50 h. The porosity of the first-stage SiBCN ceramic matrix composite is controlled below 30%. The second-stage SiBCN ceramic matrix composite is obtained by depositing the SiBCN matrix using precursor infiltration and pyrolysis method. The porosity of the second-stage SiBCN ceramic matrix composite is controlled below 20%. The precursor used for preparing the SiBCN ceramic matrix by the precursor infiltration and pyrolysis method (PIP) is polyborosilazane. The viscosity of the precursor is below 20 mPa·S. The free radical initiator used for the precursor is a peroxide initiator or / and an azo initiator. The addition amount of the free radical initiator is 0.1 - 5 wt% of the mass of polyborosilazane. The third-stage SiBCN ceramic matrix composite is obtained by depositing the SiBCN matrix using secondary chemical vapor infiltration. The porosity of the third-stage SiBCN ceramic matrix composite reaches below 6%. The parameters of the secondary chemical vapor infiltration method include: using NH3 as the nitrogen source, BCl3 as the boron source, trichloromethylsilane (MTS) as the silicon and carbon source, H2 as the carrier gas, and N2 and Ar as the dilution gases. The precursor is introduced into the furnace and deposited at 0.01 - 3 KPa and 600 - 1000 °C for 40 - 60 h.

2. The preparation method according to claim 1, wherein, The fiber preform includes a carbon fiber preform and a SiC fiber preform. The carbon fiber preform includes a carbon fiber needled preform, a carbon fiber two-dimensional cloth laminated preform, or a carbon fiber two-dimensional cloth stitched preform. The SiC fiber preform includes a SiC fiber cloth, a SiC fiber two-dimensional laminated preform, a SiC fiber two-dimensional stitched preform, a SiC fiber three-dimensional braided preform, a SiC fiber 2.5D braided preform.

3. The preparation method according to claim 1, characterized in that, An interface phase layer is deposited on the surface of the fibers in the fiber preform. The interface phase layer includes a PyC interface phase layer, a BN interface phase layer, a multi-layer (PyC / SiC)m interface phase layer with alternating deposition of PyC and SiC, and a multi-layer (BN / SiC)n interface phase layer with alternating deposition of BN and SiC, where m≥1 and n≥1. The total thickness of the interface phase layer is 50 - 5000 nm.

4. The preparation method according to claim 1, characterized in that, When initially depositing the SiBCN matrix in the fiber preform using chemical vapor infiltration to obtain the first-stage SiBCN ceramic matrix composite, the molar ratio of NH3 to BCl3 is 0.5 - 20; the molar ratio of BCl3 to MTS is 0.3 - 30; the molar ratio of N2 to BCl3 in the dilution gas is 5 - 25; the molar ratio of N2 to Ar is 0.5 - 10.

5. The preparation method according to claim 1, characterized in that, The peroxy initiator is at least one of lauroyl peroxide and dicumyl peroxide; the azo initiator is 2,2'-azobisisoheptonitrile.

6. The preparation method according to claim 1, characterized in that, The process for preparing the SiBCN ceramic matrix by the precursor impregnation pyrolysis method includes: impregnation, curing, and pyrolysis to obtain the second-stage SiBCN ceramic matrix composite; The impregnation time is 1 to 2 h, and the impregnation pressure is 0 Pa to 5 MPa; The curing temperature is 50 to 200 °C, and the curing time is 1 to 20 h; The pyrolysis temperature is 900 to 1400 °C, and the pyrolysis time is 1 to 2 h; The number of times of impregnation, curing, and pyrolysis is 3 to 10 times.

7. The preparation method according to claim 1, characterized in that, When the SiBCN matrix is deposited by the secondary chemical vapor infiltration method to obtain the third-stage SiBCN ceramic matrix composite, the molar ratio of NH3 to BCl3 is 0.5 to 20, the molar ratio of BCl3 to MTS is 0.05 to 5, the molar ratio of the dilution gas N2 to BCl3 is 5 to 25, and the molar ratio of N2 to Ar is 0.5 to 10.

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