SiBCN interface layer, SiBCN interface layer protects SiC f / SiC ceramic matrix composite and its preparation method

Abstract

The present invention relates to a SiBCN interface layer, a SiBCN interface layer for protecting a SiCf / SiC ceramic matrix composite material, and a preparation method thereof. Among them, the preparation method of the SiBCN interface layer includes: (1) fixing the fiber preform with a fixture and placing it in the reaction chamber of the furnace, and heating it to a deposition temperature of 600-850 ο °C under vacuum and holding for 0.5 h to 2 h; (2) using trichloromethylsilane as the silicon source and carbon source with the formula CH3Cl3Si, BCl3 as the boron source, NH3 as the nitrogen source, H2 as the dilution gas and carrier gas, and Ar as the dilution gas, controlling NH3 and BCl3 to be transported into the reaction chamber through different conveying pipelines respectively, and depositing for 2 h to 20 h at 0.01-3 KPa and 600-850 °C to prepare a SiBCN interface layer on the fiber surface in the fiber preform; (3) subjecting the fiber preform deposited with the SiBCN interface layer to a stabilization treatment to obtain the high-performance SiBCN interface layer.

Description

Technical Field

[0001] The present invention relates to a high-performance SiBCN interface layer, a SiC fiber-reinforced SiC ceramic matrix composite material protected by the SiBCN interface layer, and a preparation method thereof, belonging to the technical field of preparation of fiber-reinforced ceramic matrix composite materials. Background Art

[0002] SiC f / SiC ceramic matrix composite material is a new type of high-temperature thermal structure material, which has high specific strength and modulus, low density, excellent thermochemical stability and oxidation resistance, etc., and has been successfully applied to high-temperature structural components such as the outer ring of an aero-engine turbine, the inner lining of a combustion chamber, turbine blades, tail nozzle regulating vanes, and sealing sheets. These structural components need to withstand the repeated scouring of high-temperature gas and other complex environments during use, and the stability of the material in a high-temperature oxidation environment plays a decisive role in the successful use of the material. The interface phase, as an important part of the entire SiC f / SiC ceramic matrix composite material, plays a key role in the effective exertion of the mechanical properties of the material. Therefore, it is particularly important to carry out the research and development of the interface phase.

[0003] Silicon boron carbon nitride (SiBCN) ceramic is a high-temperature structural ceramic material, which has excellent high-temperature resistance, thermal shock resistance, creep resistance, oxidation resistance and ablation resistance, and its oxidation resistance is better than that of traditional SiC and Si3N4 ceramics. In recent years, it has received extensive attention and key research as the interface layer and matrix phase in ceramic matrix composites. At present, the methods for preparing SiBCN ceramics mainly include chemical vapor deposition method, polymer pyrolysis method and mechanical alloying method, etc. In the polymer pyrolysis method, due to the overflow of small molecules during the high-temperature pyrolysis of the precursor, it is easy to cause the surface of the generated SiBCN interface layer to be non-dense and have pores, and there are easily cracks on the surface, thus unable to completely and effectively protect the fibers; in the mechanical alloying method, due to the need for high-temperature hot pressing sintering during the preparation process, it is easy to damage the SiC fibers, and at the same time it is only suitable for the preparation of specimens with simple shapes and is not suitable for the preparation of complex-shaped structural components; while the chemical vapor deposition method has significant advantages such as controllable precursor components and product components, high product purity, low deposition temperature, and low fiber damage, and is the most promising preparation method for depositing the SiBCN interface coating inside the fiber preform.

[0004] At present, there are few reports on the preparation of SiBCN interfacial coatings by chemical vapor deposition (CVD) method and their application in ceramic matrix composites. Chinese Patent 1 (Application No. 201310178800.8) discloses a chemical vapor deposition method for Si-B-C-N amorphous ceramics, which uses SiCH3Cl3 or SiCl4, BCl3, and NH3 as precursors, and hydrogen and argon as carrier gas and dilution gas. A SiBCN interface was successfully prepared on the surface of carbon fiber, but it did not give the specific numerical values of the material properties when using SiBCN as the interfacial coating. Based on the process parameters and conditions mentioned in the patent, it is impossible to obtain SiC fiber-reinforced ceramic matrix composites with high mechanical properties (three-point bending strength) by only depositing the SiBCN interfacial phase, because the material properties are not only determined by the interfacial phase, but also the matrix density determines to a great extent the requirements of the material's mechanical properties for the interfacial phase. Moreover, SiC fibers are completely different from carbon fibers, and there is no comparability between them. Chinese Patent 2 (Application No. 202110323658.6) discloses the preparation of a SiBCN interfacial layer by chemical vapor deposition method. When N2 / Ar is used as the dilution gas, the white by-products on the surface of the fiber bundle are significantly reduced, and the deposition effect of the interfacial coating is significantly improved. When H2 / Ar is used as the dilution gas, the surface of the fiber bundle is wrapped by white by-products, and the interface cannot uniformly and effectively wrap the fibers, which will have an adverse effect on the subsequent matrix densification and material properties of the material. Sun Xun published "Effects of CVD SiBCN interphaseson mechanical and dielectric properties ofSiC f / SiC composites fabricated viaa PIP process" in the journal "Ceramics International". He used borazine and liquid polycarbosilane as precursors to prepare a SiBCN interface on the surface of KD-II SiC fibers and used the precursor infiltration pyrolysis (PIP) method to densify the material. Polycarbosilane (PCS) was used as the organic precursor. Although the prepared SiC / SiC material with a SiBCN interfacial phase has excellent antioxidant properties, the three-point bending strength of the material is significantly low (only 69.2 MPa), and the fracture displacement of the material is also significantly low. The mechanical properties of the material far from meet the requirements for engineering applications. Summary of the Invention

[0005] Aiming at the current situation that the mechanical properties of SiC f / SiC ceramic matrix composites are low when using SiBCN as the interfacial phase, the present invention provides a high-performance SiBCN interfacial layer and its preparation method, and a SiBCN interfacial layer for protecting SiC f / SiC ceramic matrix composites. Specifically, the SiBCN interface coating prepared by the method provided by the present invention has excellent interface debonding and mechanical transfer effects. The prepared material can meet the requirements of actual engineering applications to a certain extent. Moreover, the method provided by the present invention has strong repeatability, can be effectively regulated, and has a simple interface deposition operation in terms of the interface composition, thickness, uniformity, etc., providing a new research idea and method for further developing the interface phase for SiC f / SiC composites.

[0006] In a first aspect, the present invention provides a method for preparing a high-performance SiBCN interface layer, which is characterized by comprising: (1) fixing the fiber preform with a fixture and placing it in the reaction chamber of the furnace, heating it to the deposition temperature of 600-850 °C in a vacuum state and holding for 0.5 h-2 h; (2) using trichloromethylsilane as the silicon source and carbon source with CH3Cl3Si, BCl3 as the boron source, NH3 as the nitrogen source, H2 as the dilution gas and carrier gas, and Ar as the dilution gas, controlling NH3 and BCl3 to be respectively transported into the reaction chamber through different delivery pipes, and depositing for 2 h-20 h at 0.01-3 KPa and 600-850 °C to prepare a SiBCN interface layer on the fiber surface in the fiber preform; (3) subjecting the fiber preform deposited with the SiBCN interface layer to stabilization treatment to obtain the high-performance SiBCN interface layer

[0007] Preferably, in step (1), the SiC fiber preform includes at least one of SiC fiber bundles, SiC fiber cloth, SiC fiber two-dimensional laminates, SiC fiber two-dimensional stitching, SiC fiber 3D braids, and SiC fiber 2.5D braid preforms.

[0008] Preferably, in step (1), the mold includes one of a graphite mold, an alumina ceramic mold, a silicon carbide ceramic mold, and a silicon nitride ceramic mold; the vacuum degree of the vacuum state is below 5 Pa, preferably below 3 Pa.

[0009] Preferably, in step (1), the heating system of the deposition temperature includes: the heating rate below 500 °C is 6-10 °C / min, and the heating rate above 500 °C is 1-5 °C / min.

[0010] Preferably, in step (2), the molar ratio of NH3 to BCl3 is 0.5-20; the molar ratio of BCl3 to MTS is 0.1-5; the molar ratio of the dilution gas Ar to BCl3 is 5-30; the molar ratio of H2 to BCl3 is 0.5-30.

[0011] Preferably, in step (3), the temperature of the stabilization treatment is 1100-1500 °C, and the time is 0.5-3 h.

[0012] In a second aspect, the present invention provides a SiC fiber preform protected by a SiBCN interface layer prepared by the preparation method described above. The thickness of the SiBCN interface layer in the SiC fiber preform protected by the SiBCN interface layer does not exceed 2 μm.

[0013] In a third aspect, the present invention provides a method for preparing a SiBCN interface layer protected SiC f / SiC ceramic matrix composite, comprising: (1) performing preliminary SiC densification on the SiC fiber preform protected by the SiBCN interface layer according to claim 7 by chemical vapor infiltration process to obtain a preliminarily densified SiBCN interface layer protected SiC f / SiC ceramic matrix composite; impregnating the obtained preliminarily densified SiBCN interface layer protected SiC f / SiC ceramic matrix composite with a liquid resin solution, taking it out and then curing and pyrolyzing; (2) repeating the impregnation-curing-pyrolysis in step (1) at least 2 times to obtain a carbon-containing porous preform; (3) performing silicon infiltration on the carbon-containing porous preform by reactive melt deposition method to obtain the SiBCN interface layer protected SiC f / SiC ceramic matrix composite.

[0014] Preferably, the parameters for performing preliminary SiC densification by chemical vapor infiltration process include: using trichloromethylsilane as the SiC precursor; the dilution gases are hydrogen and argon, with a molar ratio of 1 to 5, and the total flow rate of the dilution gases is 1000 to 4000 ml / min; the carrier gas is hydrogen, with a flow rate of 100 to 200 ml / min; the infiltration temperature is 850 to 1050 °C, the infiltration pressure is 3 to 20 KPa, and the infiltration time is 20 to 100 hours.

[0015] Preferably, the liquid resin in the liquid resin solution includes at least one of phenolic resin, furfural resin, and pitch resin; the organic solvent in the liquid resin solution is at least one of polyethylene glycol solution, ethanol, ethylene glycol, glycerol, furfuryl alcohol, gasoline, alcohol, formaldehyde, glucose solution, and sucrose solution; preferably, the concentration of the polyethylene glycol solution is 5 to 20 wt%, and the solvent is selected from at least one of alcohol, gasoline, glycerol, polyethylene glycol, and formaldehyde; preferably, the concentration of the glucose solution is 30 to 60 wt%, and the solvent is selected from at least one of ethylene glycol, glycerol, glucose, furfuryl alcohol, and formaldehyde; preferably, the concentration of the sucrose solution is 30 to 60 wt%, and the solvent is selected from at least one of ethanol, ethylene glycol, glycerol, and sucrose.

[0016] Preferably, the vacuum degree of the impregnation is 1-10 KPa, and the impregnation time is 10-120 minutes; the curing temperature is 100-200 °C, and the curing time is 1-12 h, preferably 5-12 hours; the pyrolysis temperature is 700-1000 °C, and the pyrolysis time is 0.5-3 h, preferably 2-3 hours.

[0017] Preferably, the parameters for silicon infiltration treatment by the reactive melt deposition method include: the melt infiltration temperature is 1420-1600 °C, and the melt infiltration time is 0.5-2 h.

[0018] In a second aspect, the present invention provides a SiC f / SiC ceramic matrix composite protected by a SiBCN interface layer obtained according to the above preparation method.

[0019] Beneficial effects of the present invention:

[0020] (1) The present invention uses the low-pressure chemical vapor deposition method to prepare a SiBCN interface phase inside the SiC fiber preform. Through the effective regulation of the interface phase composition, thickness, structure, and uniformity, the interface phase can effectively deflect internal cracks of the material, and the interface phase can achieve effective debonding, playing a good strengthening and toughening effect;

[0021] (2) The present invention uses the chemical vapor infiltration method to preliminarily densify SiC on the SiBCN interface fiber preform. By regulating the SiC matrix content, effective protection of single fibers in the fiber preform is achieved. By regulating the pore distribution and content of porous carbon in the carbon-containing porous preform, the erosion of fibers during the silicon infiltration process by the reaction melt infiltration method is slowed down. The combined use of the two methods significantly reduces the porosity of the prepared material and improves the mechanical properties of the material. The bending strength of the material is not less than 350 MPa, and the mechanical properties far exceed those of existing SiC / SiC composites with a SiBCN interface phase prepared by the same type of method. Description of the drawings

[0022] Figure 1 It is a low-magnification scanning electron microscope cross-sectional view of the inside of the SiC fiber preform after depositing the SiBCN interface phase in Example 1 of the present invention;

[0023] Figure 2 It is an energy spectrum analysis (EDS) diagram of the SIBCN interface on the surface of the SiC fiber in Example 1 of the present invention;

[0024] Figure 3 It is a three-point bending-strain curve diagram of the SiC f / SiC ceramic matrix composite protected by the SiBCN interface layer prepared in Examples 1, 2, and 3 of the present invention;

[0025] Figure 4The SiC protected by the SiBCN interface layer prepared in Example 3 of the present invention f / SEM image of the polished sample of the SiC ceramic matrix composite material Specific implementation mode

[0026] The present invention will be further described through 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

[0027] Aiming at the deficiencies in the performance of SiC fiber-reinforced SiC ceramic matrix composites when the existing SiBCN is used as the interface layer, the present invention uses chemical vapor infiltration to prepare a SiBCN interface coating on the surface of SiC fibers and combines chemical vapor infiltration and reactive melt infiltration methods to prepare a SiBCN interface layer to protect SiC fiber-reinforced SiC ceramic matrix composites

[0028] Hereinafter, an exemplary description of the SiBCN interface layer protecting SiC f / Preparation method of SiC ceramic matrix composite material, and the preparation method includes the following steps

[0029] Preparation of SiBCN interface-protected SiC fiber preform. Using chemical vapor deposition method, SiBCN is deposited on the surface of the SiC fiber preform to obtain a preliminary SiBCN interface-protected SiC fiber preform. After stabilization treatment, the SiBCN interface-protected SiC fiber preform is obtained

[0030] In some implementation modes, the SiC fiber preform can be selected from at least one of SiC fiber bundles, SiC fiber cloths, SiC fiber two-dimensional laminates, SiC fiber two-dimensional stitched, SiC fiber 3D braids, and SiC fiber 2.5D braided preforms

[0031] In some implementation modes, the fiber preform is placed in a vertical chemical vapor deposition furnace, and the corresponding precursor is introduced into the furnace to obtain a SiBCN-coated fiber preform. The process of the chemical vapor deposition method is as follows: the fiber preform is fixed with a graphite fixture and placed in the furnace. After evacuating and flushing multiple times, it is heated to 600-850 °C and kept warm for 0.5-2 h under vacuum (preferably, the heating rate below 500 °C is 6-10 °C / min, and the heating rate above 500 °C is 1-5 °C / min); then, the chemical vapor deposition precursor gas is introduced, and deposition is carried out at 0.01-3 KPa and 600-850 °C for 2-20 h

[0032] Among them, in the chemical vapor deposition precursor gas: CH3Cl3Si (trichloromethylsilane, MTS) serves as the silicon source and carbon source, with a flow rate of 100 - 300 ml / min; BCl3 serves as the boron source, with a flow rate of 10 - 1500 ml / min; NH3 serves as the nitrogen source, with a flow rate of 50 - 6000 ml / min; H2 serves as the dilution gas and carrier gas, with a flow rate of 5 - 45000 ml / min; Ar serves as the dilution gas, with a flow rate of 500 - 9000 ml / min. In some embodiments, the molar ratio of NH3 to BCl3 can be controlled to be 0.5 - 20, the molar ratio of BCl3 to MTS can be 0.1 - 5, the molar ratio of the dilution gas Ar to BCl3 can be 5 - 30, and the molar ratio of H2 to BCl3 can be 0.5 - 30. In the present invention, the content of Si element in the SiBCN interface is regulated by adjusting the molar ratio of BCl3 to MTS, and finally the phase structure of the SiBCN interface is regulated, thereby regulating the material properties.

[0033] Preferably, the purity of MTS is above 97%, the purity of BCl3 is 99.9%, and the purity of the remaining gases is 99.999%; NH3 and BCl3 are respectively transported to the chemical vapor deposition reaction chamber through different pipelines.

[0034] Preferably, in the chemical vapor deposition furnace, the fixed fiber preform can adopt a porous graphite fixture (with a pore diameter of 50 mm), and the shape can be rectangular, square, etc. The opening shape can be diamond-shaped, polygonal, circular, square, rectangular, etc., and the number of holes can be 2 or more.

[0035] In some embodiments, the temperature of the stabilization treatment is 1100 - 1500 °C, and the stabilization treatment time is 0.5 - 3 h. Through the stabilization treatment, the atomic migration between grains in the interface phase can be promoted, the atomic structure rearrangement and interface structure transformation can be promoted, making the interface structure more stable. In the present invention, the stabilization temperature is set within this range because too high a stabilization temperature will cause damage to the fiber strength, which is not conducive to the subsequent material mechanical properties, and too low a stabilization temperature cannot effectively cause sufficient structural rearrangement of the interface phase.

[0036] In some embodiments, in the SiBCN interface protecting the SiC fiber preform, the final fiber volume fraction of the fiber preform can be controlled to be 18 vol% or more, preferably above 22 vol%; the content of the SiBCN interface coating can be 3 - 30 wt%. By regulating the fiber volume fraction to be above 18%, it is beneficial to maximize the fiber performance and make full use of the reinforcement effect of the fiber. By controlling the interface coating content within 3 - 30 wt%, the interface phase thickness can be indirectly controlled, thereby effectively alleviating the thermal stress generated during the material preparation process. The interface phase plays a good role in strengthening and toughening.

[0037] In some embodiments, the thickness of the SiBCN interfacial protective layer can be 50 nm to 2 μm.

[0038] The SiBCN interface protects the SiC fiber preform for preliminary densification. The SiBCN interface-protected SiC fiber preform is preliminarily densified with SiC by a chemical vapor infiltration (CVI) process to obtain a preliminarily densified SiBCN interface layer-protected SiC f / SiC ceramic matrix composite.

[0039] In some embodiments, during the preliminary SiC densification process by the chemical vapor infiltration process, trichloromethylsilane (MTS) is used as the SiC precursor; the dilution gases are hydrogen and argon with a molar ratio of 1 to 5, and the total flow rate of the dilution gases is 1000 to 4000 ml / min; the carrier gas is hydrogen with a flow rate of 100 to 200 ml / min. Controlling the dilution gas flow rate to be higher than the carrier gas flow rate can effectively dilute the MTS concentration during the SiC densification process and prevent the premature closing of pores on the material surface due to excessive concentration, which affects the further densification of the subsequent matrix.

[0040] In some embodiments, during the preliminary SiC densification process by the chemical vapor infiltration process, the infiltration temperature can be 850 to 1050 °C, the infiltration pressure can be 3 to 20 KPa, and the infiltration time can be 20 to 100 hours. By controlling the process parameters within the above ranges, the maximum uniform deposition of the SiC matrix inside the material can be effectively achieved, and the effective infiltration of the SiC matrix inside the material can be realized.

[0041] In some embodiments, it is possible to control the SiC matrix weight gain ratio in the preliminarily densified SiBCN interface layer-protected SiC f / SiC ceramic matrix composite to be 20 to 300%. By pre-depositing a certain amount of CVI SiC matrix inside the matrix, the effective filling of the pores inside the fiber bundles in the material can be achieved, thereby improving the material density and the matrix strength.

[0042] SiBCN interface layer-protected SiC f / SiC ceramic matrix composite preparation. The surface of the preliminarily densified SiBCN interface layer-protected SiC f / SiC ceramic matrix composite is polished, cleaned, dried, and then impregnated with a liquid resin and an organic solvent. After taking it out, it is cured, dried, and pyrolyzed. The impregnation-curing-pyrolysis operation is repeated 2 to 6 times to obtain a carbon-containing porous preform. After removing impurities from the surface of the obtained carbon-containing porous preform after pyrolysis, it is put into a furnace and subjected to silicon infiltration treatment by the reaction melt infiltration (RMI) method for further densification to obtain the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite.

[0043] In some embodiments, the liquid resin may be at least one of phenolic resin, furfural resin, and asphalt resin; the organic solvent may be at least one of polyethylene glycol, ethanol, glycerol, furfuryl alcohol, gasoline, alcohol, formaldehyde, glucose, and sucrose solution.

[0044] In some embodiments, the vacuum degree of impregnation is 1-10 KPa, and the impregnation time can be 10-120 minutes; the curing temperature is 100-200 °C, and the curing time is 1-12 h, preferably 5-12 hours; the pyrolysis temperature is 700-1000 °C, and the pyrolysis time is 0.5-3 h, preferably 2-3 hours. Controlling the material impregnation under a low-pressure environment can effectively improve the material impregnation efficiency. At the same time, controlling the curing temperature between 100-200 °C can effectively shorten the curing time, and controlling the pyrolysis temperature between 700-1000 °C can maximize the completion of pyrolysis while not affecting the material properties.

[0045] In some embodiments, in reactive melt infiltration, the infiltration temperature can be 1420-1600 °C, and the infiltration time can be 0.5-2 h. By regulating the infiltration temperature and infiltration time within this range, the infiltration process can be effectively ensured while avoiding damage to the fiber strength caused by too high infiltration temperature.

[0046] The SiBCN interface coating prepared by the present invention realizes good bonding with SiC fibers, has good physical and chemical compatibility and thermal stability, and realizes good mechanical strengthening and toughening effects on SiC fibers. The present invention adopts a method combining CVI and RMI. Compared with the existing CVI and precursor infiltration pyrolysis method (PIP) usage methods, it avoids the pore defects caused by the volume shrinkage of the precursor and the overflow of small molecules in the infiltration pyrolysis process, saves the material preparation cycle, improves the material preparation efficiency, and at the same time adopts the CVI and RMI processes, reduces the internal porosity of the material, improves the mechanical properties of the material, and finally obtains a high-performance SiBCN interface layer with energy consumption mechanisms such as good interface debonding, fiber pull-out, and crack deflection to protect SiC fiber-reinforced ceramic matrix composites.

[0047] The SiBCN interface coating prepared by the present invention has good bonding strength with SiC fibers, and has good mechanical strengthening and toughening effects and high-temperature oxidation resistance. Compared with the prior art, the SiBCN interface layer-protected SiC fiber-reinforced ceramic matrix composite prepared by the present invention has excellent mechanical properties and high-temperature oxidation resistance. Energy consumption mechanisms such as interface debonding, fiber pull-out, and crack deflection can be fully and effectively exerted during the material fracture failure process, and the mechanical properties of the material have good repeatability.

[0048] The porosity of the finally obtained SiC fiber-reinforced composite material is tested by the Archimedes drainage method and is ≤6%; the flexural strength of the obtained SiC fiber-reinforced composite material is tested by the three-point bending strength test method of the composite material and is ≥300 MPa, preferably ≥350 MPa, and the flexural strain is ≥0.4%, preferably ≥0.6%.

[0049] The following further lists 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 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 a selection within a suitable range through the description in this article, rather than being limited to the specific values in the following examples.

[0050] Example 1

[0051] The SiBCN interface layer protects SiC f / SiC ceramic matrix composite material preparation method includes the following steps:

[0052] (1) Preparation of SiBCN interface-protected SiC fiber preform. Fix the SiC fiber cloth with a size of 100×180 mm with graphite jigs with square holes with a side length of 30×30 mm on both sides, place the sample in the reaction chamber of the furnace, evacuate and inflate 2 times. Under vacuum conditions, heat it to 500 °C at a rate of 10 °C per minute, keep it warm for half an hour, and then heat it to 850 °C at a rate of 5 °C per minute and keep it warm for 1 h; then, introduce precursors and dilution gases such as trichloromethylsilane (MTS), NH3, BCl3, H2, and Ar into the furnace, control the molar ratio of NH3 and BCl3 to be 2, the molar ratio of BCl3 and MTS to be 1.5, the molar ratio of dilution gas Ar and BCl3 to be 10, and the molar ratio of H2 and BCl3 to be 10, and deposit at 3 KPa and 820 °C for 15 h; then take out the SiC fiber with the SiBCN interface coating deposited and put it into the furnace for stabilization treatment. The stabilization treatment temperature is 1100 °C and the stabilization treatment time is 3 h to obtain the SiBCN interface-protected SiC fiber preform.

[0053] (2) The SiBCN interface protects the SiC fiber preform for initial densification. The SiBCN interface-protected SiC fiber preform is placed in a chemical vapor infiltration furnace for initial CVI SiC densification treatment. The flow rate of the carrier gas hydrogen is 150 ml / min, the flow rate of the diluent gas hydrogen is 1500 ml / min, the flow rate of argon is 300 ml / min, the infiltration temperature is 990 °C, the furnace pressure is 5 KPa, and the infiltration time is 50 hours, obtaining the SiC protected by the initially densified SiBCN interface layer f / SiC ceramic matrix composite; wherein, the weight gain ratio of CVI SiC is 30%.

[0054] (3) Preparation of SiBCN interface layer-protected SiC f / SiC ceramic matrix composite. The surface of the initially densified SiBCN interface layer-protected SiC f / SiC ceramic matrix composite is polished, cleaned and dried, and then the sample is subjected to 3 times of impregnation and pyrolysis treatment with 100 g of phenolic resin, 30 g of furfuryl alcohol, 30 g of polyethylene glycol and 300 g of glycerol. The impregnation vacuum is 5 KPa, the impregnation time is 120 minutes, the curing temperature is 150 °C, the curing time is 8 hours, the pyrolysis temperature is 950 °C, and the time is 2.5 hours; then, after the surface of the impregnated and pyrolyzed sample is cleaned and dried, it is put into an infiltration furnace for the final silicon infiltration treatment. The infiltration temperature is 1450 °C, the infiltration time is 1.5 hours, obtaining the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite.

[0055] Figure 1 This is a low-magnification scanning electron microscope image of the cross-section of the SiC fiber preform after depositing the SiBCN interface phase in Example 1 of the present invention. It can be seen from the figure that the SiBCN interface coating uniformly penetrates into the fiber preform.

[0056] Figure 2 This is an energy dispersive spectroscopy (EDS) image of the SIBCN interface on the surface of the SiC fiber in Example 1 of the present invention. It can be seen from the figure that the prepared SiBCN interface is mainly composed of five elements: Si, B, C, N, and O.

[0057] It is known through testing that the porosity of the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite prepared in Example 1 is 4.80%, the flexural strength of the material is 358.43 MPa, and the flexural strain is 0.6%.

[0058] Example 2

[0059] The preparation method of the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite includes the following steps:

[0060] (1) Preparation of SiBCN interfacial protection SiC fiber preform. The SiC fiber cloth with a size of 300×200 mm is fixed with graphite jigs with rectangular holes with side lengths of 20×25 mm on both sides. The sample is placed in the reaction chamber of the furnace, evacuated and filled with gas twice. Under vacuum conditions, it is heated to 500 °C at a rate of 10 °C per minute, held for half an hour, and then heated to 800 °C at a rate of 5 °C per minute. After holding for 1 h; then, precursors and dilution gases such as trichloromethylsilane (MTS), NH3, BCl3, H2, and Ar are introduced into the furnace. Control the molar ratio of NH3 and BCl3 to be 10, the molar ratio of BCl3 and MTS to be 2.5, the molar ratio of dilution gas Ar and BCl3 to be 10, and the molar ratio of H2 and BCl3 to be 10. Deposit at 3 KPa and 840 °C for 13 h; then take out the SiC fibers with the SiBCN interfacial coating deposited and put them into the furnace for stabilization treatment. The stabilization treatment temperature is 1130 °C and the stabilization treatment time is 3 h to obtain the SiBCN interfacial protection SiC fiber preform.

[0061] (2) Preliminary densification of SiBCN interfacial protection SiC fiber preform. The SiBCN interfacial protection SiC fiber preform is put into a chemical vapor infiltration furnace for preliminary CVI SiC densification treatment. The flow rate of carrier gas hydrogen is 150 ml / min, the flow rate of dilution gas hydrogen is 1500 ml / min, the flow rate of argon is 300 ml / min, the infiltration temperature is 990 °C, the pressure in the furnace is 5 KPa, and the infiltration time is 65 hours to obtain the SiBCN interfacial layer protected SiC f / SiC ceramic matrix composite; among them, the weight gain ratio of CVI SiC is 40%.

[0062] (3) Preparation of SiBCN interfacial layer protected SiC f / SiC ceramic matrix composite. Polish the surface of the SiBCN interfacial layer protected SiC f / SiC ceramic matrix composite. After cleaning and drying, use 80 g of phenolic resin, 40 g of furfuryl alcohol, 30 g of polyethylene glycol, and 300 g of glycerol to perform 3 impregnation and pyrolysis treatments on the sample. The impregnation vacuum is 5 KPa, the impregnation time is 120 minutes, the curing temperature is 150 °C, the curing time is 8 hours, the pyrolysis temperature is 950 °C, and the time is 2.5 hours; then, after cleaning and drying the surface of the sample after impregnation and pyrolysis, put it into a melt infiltration furnace for the final silicon infiltration treatment. The melt infiltration temperature is 1450 °C and the melt infiltration time is 1.5 hours to obtain the SiBCN interfacial layer protected SiC f / SiC ceramic matrix composite.

[0063] It can be known through testing that the SiBCN interfacial layer protected SiC prepared in Example 2f The porosity of the / SiC ceramic matrix composite is 4.50%, the flexural strength of the material is 373.54 MPa, and the flexural strain is 0.66%.

[0064] Example 3

[0065] The SiBCN interface layer protects SiC f The preparation method of the / SiC ceramic matrix composite includes the following steps:

[0066] (1) Preparation of SiBCN interface-protected SiC fiber preform. Fix the SiC fiber cloth with a size of 100×100 mm on both sides with porous graphite jigs with a pore diameter of φ25 mm. Place the specimen in the reaction chamber of the furnace, evacuate and fill with gas 2 times. Under vacuum conditions, heat it to 500 °C at a rate of 10 °C per minute, hold for half an hour, and then heat it to 780 °C at a rate of 5 °C per minute and hold for 1 h; Then, introduce precursors and diluent gases such as trichloromethylsilane (MTS), NH3, BCl3, H2, and Ar into the furnace. The molar ratio of NH3 and BCl3 is 15, the molar ratio of BCl3 and MTS is 4, the molar ratio of diluent gas Ar and BCl3 is 10, and the molar ratio of H2 and BCl3 is 10. Deposit at 2.5 KPa and 830 °C for 14 h; Then take out the SiC fiber deposited with the SiBCN interface coating and put it into the furnace for stabilization treatment. The stabilization treatment temperature is 1150 °C and the stabilization treatment time is 3 h to obtain the SiBCN interface-protected SiC fiber preform.

[0067] (2) Preliminary densification of the SiBCN interface-protected SiC fiber preform. Put the SiBCN interface-protected SiC fiber preform into a chemical vapor infiltration furnace for preliminary CVI SiC densification treatment. The flow rate of carrier gas hydrogen is 150 ml / min, the flow rate of diluent gas hydrogen is 1500 ml / min, the flow rate of argon is 300 ml / min, the infiltration temperature is 990 °C, the pressure in the furnace is 5 KPa, and the infiltration time is 100 hours to obtain the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite; Among them, the weight gain ratio of CVI SiC is 60%.

[0068] (3) SiBCN interface layer protects SiC f Preparation of / SiC ceramic matrix composite. The SiBCN interface layer-protected SiC fFor the surface polishing of the SiC ceramic matrix composite, after cleaning and drying, the sample was subjected to three impregnation and pyrolysis treatments with 90 g of phenolic resin, 50 g of furfuryl alcohol, 30 g of polyethylene glycol, and 300 g of glycerol. Among them, the impregnation vacuum was 5 KPa, the impregnation time was 120 minutes, the curing temperature was 150 °C, the curing time was 8 hours, the pyrolysis temperature was 950 °C, and the time was 2.5 hours; then, after cleaning and drying the surface of the sample after impregnation and pyrolysis, it was put into an infiltration furnace for the final silicon infiltration treatment. The infiltration temperature was 1450 °C, and the infiltration time was 1.5 hours to obtain the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite

[0069] It can be known through testing that the porosity of the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite prepared in Example 3 is 4.28%, the flexural strength of the material is 407.90 MPa, and the flexural strain is 0.85%.

[0070] Figure 3 For the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite prepared in Examples 1, 2, and 3 of the present invention. It can be seen from the figure that the composite material prepared by the present invention exhibits obvious ductile fracture characteristics

[0071] Figure 4 For the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite prepared in Example 3 of the present invention. It can be seen from the figure that the interior of the material prepared by the method of the present invention is very dense, and almost no large pores can be seen

[0072] Example 4

[0073] For the preparation process of the composite material in this Example 4, refer to Example 1. The difference is that in step (1), the SiC fiber with the SiBCN interface coating deposited was taken out and put into the furnace for stabilization treatment. The stabilization treatment temperature was 1450 °C, and the stabilization treatment time was 3 h to obtain the SiBCN interface-protected SiC fiber preform. The porosity of the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite prepared in this example is 4.38%, the flexural strength of the material is 310.1 MPa, and the flexural strain is 0.61%.

[0074] Example 5

[0075] For the preparation process of the composite material in Example 5, refer to Example 1, with the difference that: in step (1), the SiC fibers with the SiBCN interface coating deposited are taken out and put into the furnace for stabilization treatment. The stabilization treatment temperature is 1500 °C and the stabilization treatment time is 3 h to obtain the SiBCN interface-protected SiC fiber preform. The porosity of the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite is 3.88%, the flexural strength of the material is 319.8 MPa, and the flexural strain is 0.61%.

[0076] Example 6

[0077] For the preparation process of the composite material in Example 6, refer to Example 1, with the difference that: in step (1), the SiC fibers with the SiBCN interface coating deposited are taken out and put into the furnace for stabilization treatment. The stabilization treatment temperature is 1000 °C and the stabilization treatment time is 3 h to obtain the SiBCN interface-protected SiC fiber preform. The porosity of the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite is 3.56%, the flexural strength of the material is 351.8 MPa, and the flexural strain is 0.48%.

[0078] Example 7

[0079] For the preparation process of the composite material in Example 7, refer to Example 1, with the difference that: in step (1), the SiC fibers with the SiBCN interface coating deposited are taken out and put into the furnace for stabilization treatment. The stabilization treatment temperature is 1600 °C and the stabilization treatment time is 3 h to obtain the SiBCN interface-protected SiC fiber preform. The porosity of the SiBCN interface layer-protected SiC f / SiC ceramic matrix composite is 3.78%, the flexural strength of the material is 328.1 MPa, and the flexural strain is 0.41%.

[0080] Example 8

[0081] For the preparation process of the composite material in Example 8, refer to Example 1, with the difference that: in step (3), the surface of the preliminarily densified SiBCN interface layer-protected SiC f / SiC ceramic matrix composite is polished, cleaned, dried, and then the sample is subjected to 3 impregnation and pyrolysis treatments with 50 g of phenolic resin, 50 g of furfuryl alcohol resin, 30 g of polyethylene glycol, and 300 g of glycerol. The impregnation vacuum is 5 KPa, the impregnation time is 120 minutes, the curing temperature is 150 °C, the curing time is 8 hours, the pyrolysis temperature is 950 °C, and the time is 2.5 hours. The porosity of the SiBCN interface layer-protected SiC fThe porosity of the SiC ceramic matrix composite is 4.12%, the flexural strength of the material is 345.8 MPa, and the flexural strain is 0.73%.

[0082] Example 9

[0083] For the preparation process of the composite material in this Example 9, refer to Example 1. The difference is that in step (3), the SiC protected by the preliminarily densified SiBCN interface layer f / SiC ceramic matrix composite surface was polished, and after cleaning and drying, the sample was subjected to three impregnation and pyrolysis treatments with 50 g of phenolic resin, 30 g of polyethylene glycol, 50 g of furfuryl alcohol, and 300 g of ethanol. Among them, the impregnation vacuum was 5 KPa, the impregnation time was 120 minutes, the curing temperature was 150 °C, the curing time was 8 hours, the pyrolysis temperature was 950 °C, and the time was 2.5 hours. The SiC protected by the SiBCN interface layer prepared in this example f / SiC ceramic matrix composite has a porosity of 3.56%, the flexural strength of the material is 340.8 MPa, and the flexural strain is 0.75%.

[0084] Example 10

[0085] For the preparation process of the composite material in this Example 10, refer to Example 9. The difference is that in step (3), the SiC protected by the preliminarily densified SiBCN interface layer f / SiC ceramic matrix composite surface was polished, and after cleaning and drying, the sample was subjected to three impregnation and pyrolysis treatments with 50 g of phenolic resin, 50 g of furfuryl alcohol, and 300 g of glycerol. Among them, the impregnation vacuum was 5 KPa, the impregnation time was 120 minutes, the curing temperature was 150 °C, the curing time was 8 hours, the pyrolysis temperature was 950 °C, and the time was 2.5 hours. The SiC protected by the SiBCN interface layer prepared in this example f / SiC ceramic matrix composite has a porosity of 3.45%, the flexural strength of the material is 325.7 MPa, and the flexural strain is 0.57%.

[0086] Example 11

[0087] For the preparation process of the composite material in this Example 11, refer to Example 9. The difference is that in step (3), the SiC protected by the preliminarily densified SiBCN interface layer f / SiC ceramic matrix composite surface was polished, and after cleaning and drying, the sample was subjected to three impregnation and pyrolysis treatments with 50 g of phenolic resin, 30 g of polyethylene glycol, and 300 g of ethanol. Among them, the impregnation vacuum was 5 KPa, the impregnation time was 120 minutes, the curing temperature was 150 °C, the curing time was 8 hours, the pyrolysis temperature was 950 °C, and the time was 2.5 hours. The SiC protected by the SiBCN interface layer prepared in this example fThe porosity of the SiC ceramic matrix composite is 5.02%, the flexural strength of the material is 308.0 MPa, and the flexural strain is 0.45%.

[0088] Comparative Example 1

[0089] For the preparation process of the composite material in this Comparative Example 1, refer to Example 1, with the difference that: in step (1), the SiC fibers coated with the SiBCN interface coating are taken out without stabilization treatment to obtain the SiBCN interface-protected SiC fiber preform. The SiC protected by the SiBCN interface layer prepared in this Comparative Example 1 f / SiC ceramic matrix composite has a porosity of 4.75%, a flexural strength of the material of 246.3 MPa, and a flexural strain of 0.26%.

[0090] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and alternatives to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. Preparation method of SiC f / SiC ceramic matrix composite protected by a high-performance SiBCN interface layer, characterized in that Comprising: (1) Fix the fiber preform with a fixture and place it in the reaction chamber of the furnace. Heat it to the deposition temperature of 600 - 850 °C under vacuum and hold for 0.5 h - 2 h; (2) Using trichloromethylsilane CH3Cl3Si as the silicon source and carbon source, BCl3 as the boron source, NH3 as the nitrogen source, H2 as the dilution gas and carrier gas, and Ar as the dilution gas. Control NH3 and BCl3 to be transported into the reaction chamber through different pipelines respectively, and deposit for 2 h - 20 h at 0.01 - 3 KPa and 600 - 850 °C to prepare a SiBCN interface layer on the fiber surface in the fiber preform; (3) Stabilize the fiber preform deposited with the SiBCN interface layer to obtain a SiC fiber preform protected by a high-performance SiBCN interface layer; the temperature of the stabilization treatment is 1100 - 1500 °C, and the time is 0.5 - 3 h; the thickness of the high-performance SiBCN interface layer is 50 nm - 2 μm; (4)The SiC fiber preform protected by the high-performance SiBCN interface layer obtained in the chemical vapor infiltration process step (3) is preliminarily densified with SiC to obtain a preliminarily densified SiBCN interface layer-protected SiC f / SiC ceramic matrix composite; The SiC protected by the obtained preliminarily densified SiBCN interface layer f / SiC ceramic matrix composite is impregnated with a liquid resin solution, taken out and then cured and pyrolyzed; the impregnation-curing-pyrolysis in this step is repeated at least 2 times to obtain a carbon-containing porous preform; (5) The carbon-containing porous preform is subjected to silicon infiltration treatment by reactive melt deposition to obtain the SiC / f SiC ceramic matrix composite protected by the high-performance SiBCN interface layer; The bending strength of SiC / SiC ceramic matrix composites protected by a high-performance SiBCN interface layer measured by the three-point bending strength test method of composite materials is ≥300 MPa, and the bending strain is ≥0.4%. f / SiC ceramic matrix composites have a bending strength ≥300 MPa and a bending strain ≥0.4%.

2. The preparation method according to claim 1, characterized in that, In step (1), the fiber preform includes at least one of SiC fiber bundles, SiC fiber cloth, two-dimensional SiC fiber laminates, two-dimensional stitched SiC fibers, three-dimensional woven SiC fibers, and 2.5D woven SiC fiber preforms.

3. The preparation method according to claim 1, wherein In step (1), the vacuum degree of the vacuum state is below 5 Pa.

4. The preparation method according to claim 3, characterized in that, In step (1), the vacuum degree of the vacuum state is below 3 Pa.

5. The preparation method according to claim 1, characterized in that, In step (1), the heating regime of the deposition temperature includes: the heating rate is 6 - 10 °C / min below 500 °C, and the heating rate is 1 - 5 °C / min above 500 °C.

6. The preparation method according to claim 1, characterized in that, In step (2), the molar ratio of NH3 and BCl3 is 0.5 - 20; the molar ratio of BCl3 and trichloromethylsilane is 0.1 - 5; the molar ratio of the dilution gas Ar and BCl3 is 5 - 30; the molar ratio of H2 and BCl3 is 0.5 - 30.

7. The preparation method according to claim 1, wherein The parameters for preliminary SiC densification using the chemical vapor infiltration process include: using trichloromethylsilane as the SiC precursor; the dilution gases are hydrogen and argon, with a molar ratio of 1 - 5, and the total flow rate of the dilution gases is 1000 - 4000 ml / min; the carrier gas is hydrogen, with a flow rate of 100 - 200 ml / min; The infiltration temperature is 850 - 1050 °C, the infiltration pressure is 3 - 20 KPa, and the infiltration time is 20 - 100 hours.

8. The preparation method according to claim 1, wherein The liquid resin in the liquid resin solution includes at least one of phenolic resin, furfural resin, and pitch resin; The organic solvent in the liquid resin solution is at least one of polyethylene glycol solution, ethanol, ethylene glycol, glycerol, furfuryl alcohol, gasoline, alcohol, formaldehyde, glucose solution, and sucrose solution; The concentration of the polyethylene glycol solution is 5 - 20 wt%, and the solvent is selected from at least one of alcohol, gasoline, glycerol, and formaldehyde; The concentration of the glucose solution is 30 - 60 wt%, and the solvent is selected from at least one of ethylene glycol, glycerol, furfuryl alcohol, and formaldehyde; The concentration of the sucrose solution is 30 - 60 wt%, and the solvent is selected from at least one of ethanol, ethylene glycol, and glycerol.

9. The preparation method according to claim 1, characterized in that, The vacuum degree of the impregnation is 1 to 10 KPa, and the impregnation time is 10 to 120 minutes; The curing temperature is 100 to 200 °C, and the curing time is 1 to 12 h; The pyrolysis temperature is 700 to 1000 °C, and the pyrolysis time is 0.5 to 3 h.

10. The preparation method according to claim 9, characterized in that, The curing time is 5 to 12 hours; The pyrolysis time is 2 to 3 hours.

11. The preparation method according to any one of claims 1 to 10, characterized in that, The parameters for silicon infiltration treatment by reactive melt deposition method include: the infiltration temperature is 1420 to 1600 °C, and the infiltration time is 0.5 to 2 h.

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