A SiC composite material containing a high-strength and high-modulus matrix f and a method for producing and using the same

Abstract

The application discloses a SiC f / SiC composite material containing a high-strength and high-modulus matrix and a preparation method and application thereof, and relates to the technical field of silicon carbide-based composite materials. The method comprises the following steps: preparing a CVI-BN interfacial phase in a SiC fiber preform by adopting a chemical vapor infiltration process, introducing SiC whiskers in the SiC fiber preform by adopting a gel injection molding process, and obtaining a porous composite material; placing the porous composite material in a first polycarbosilane slurry for multiple times of impregnation and pyrolysis, so as to obtain a semi-dense SiC f / SiC composite material; placing the semi-dense SiC f / SiC composite material in a second polycarbosilane slurry for multiple times of impregnation and pyrolysis, so as to obtain a dense SiC f / SiC composite material; the application promotes the formation of a continuous rigid load-carrying skeleton in the matrix by jointly modifying a PIP-SiC matrix by means of inert fillers SiC w and active fillers silicon powder, reduces the defect content of the matrix, improves the crystallinity, and purifies the components. The mechanical properties of the modified composite material are improved by more than 30%.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide-based composite materials, specifically to a SiC matrix containing high strength and high modulus. f / SiC composite materials, their preparation methods, and applications. Background Technology

[0002] The hot-section components of next-generation aero-engines operate in harsher environments with higher temperatures, coming into direct contact with high-temperature exhaust gases. They are susceptible to corrosion from these gases and subjected to intense aerodynamic and thermal fatigue loads. Silicon carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC) are thus addressed. f SiC (SiC) has become an important candidate material for hot-end components of next-generation high-performance aero-engines due to its excellent properties such as high specific strength and good temperature resistance.

[0003] SiC f The main methods for preparing SiC composite materials include chemical vapor infiltration (CVI), precursor impregnation pyrolysis (PIP), reactive melt infiltration (RMI), and combinations of these methods. The CVI method requires expensive equipment, and the resulting SiC composites... f SiC composites exhibit a large open porosity (10%–15%), making them prone to failure under high-temperature and corrosive environments. SiC prepared by the RMI method... f SiC composites typically contain a large amount of residual silicon (>10%), and their performance deteriorates sharply when the temperature exceeds the softening or melting point of Si, making them unsuitable for the high-temperature, high-stress conditions of aero-engines. The PIP method, however, offers advantages such as relatively low cost, adjustable preparation temperature, less fiber damage, and the ability to produce high-quality SiC composites. f The low porosity (~10%) and ability to fabricate complex-shaped components of SiC composites make them a low-cost option for preparing high-density SiC. f Common methods for SiC composite materials.

[0004] In SiC f In SiC composites, the matrix plays a crucial role in load transfer, shaping, and protecting SiC fibers. Among these, efficiently transferring the load to the SiC fibers is essential for achieving SiC... fThe key to high performance of / SiC composites is the high performance of the matrix. The high-efficiency transmission and load require the matrix to have high strength and high modulus characteristics. PIP method requires multiple rounds of immersion and pyrolysis to prepare high-density composites, which leads to loose distribution of PIP-SiC matrix and difficulty in continuous transmission and load; in addition, PIP-SiC matrix is converted from polymer precursor polycarbosilane (PCS), and the structure is usually amorphous, and during the ceramicization process, it is inevitable to produce severe shrinkage, accompanied by the escape of small molecule gas, resulting in cracks and micropores in the PIP-SiC matrix; at the same time, a small amount of aromatic hydrocarbon substances are difficult to escape during the pyrolysis of PCS and remain in the matrix, so that PIP-SiC matrix contains free carbon, which has low modulus and is easy to crack. As can be seen from the above, the PIP-SiC matrix is loose and difficult to continuously transmit and load, and the matrix has high defects, low crystallinity and impure composition, which seriously limits the improvement of the strength and modulus of the matrix and affects the transmission efficiency of the matrix. Therefore, improving the continuity of PIP-SiC matrix and improving the defect content, crystallinity and composition of the matrix are the keys to realizing high performance of / SiC composites. f The key to high performance of / SiC composites is the high performance of the matrix. The high-efficiency transmission and load require the matrix to have high strength and high modulus characteristics. PIP method requires multiple rounds of immersion and pyrolysis to prepare high-density composites, which leads to loose distribution of PIP-SiC matrix and difficulty in continuous transmission and load; in addition, PIP-SiC matrix is converted from polymer precursor polycarbosilane (PCS), and the structure is usually amorphous, and during the ceramicization process, it is inevitable to produce severe shrinkage, accompanied by the escape of small molecule gas, resulting in cracks and micropores in the PIP-SiC matrix; at the same time, a small amount of aromatic hydrocarbon substances are difficult to escape during the pyrolysis of PCS and remain in the matrix, so that PIP-SiC matrix contains free carbon, which has low modulus and is easy to crack. As can be seen from the above, the PIP-SiC matrix is loose and difficult to continuously transmit and load, and the matrix has high defects, low crystallinity and impure composition, which seriously limits the improvement of the strength and modulus of the matrix and affects the transmission efficiency of the matrix. Therefore, improving the continuity of PIP-SiC matrix and improving the defect content, crystallinity and composition of the matrix are the keys to realizing high performance of / SiC composites.

[0005] At present, the methods for improving the properties of PIP-SiC matrix mainly include adding inert fillers or active fillers. Inert fillers mainly include SiC particles (SiC p ), SiC whiskers (SiC w ) and SiC nanowires (SiC nws ), and active fillers mainly include Al, Ti and other powders. The commonly used filler introduction methods mainly include slurry impregnation and CVI technology. Inert fillers: when high volume fraction inert fillers are introduced by slurry impregnation technology, a large number of closed pores are often formed in SiC f / SiC composites, resulting in a decrease in density; SiC w or SiC nws is grown in situ by CVI technology, which is difficult to achieve high volume fraction, and the CVI equipment is expensive and the process cost is high. These two methods have certain limitations in controlling and improving the introduction content of fillers, and it is difficult to improve the continuity of the matrix. Active fillers: Al, Ti and other heterogeneous fillers have the problem of mismatching with SiC in thermal expansion coefficient, which aggravates the problem of impure composition of PIP-SiC matrix, and residual stress is generated during the preparation of the matrix, which affects the mechanical properties of SiC f / SiC composites. As described above, the current modification methods are difficult to solve the problems of loose distribution of PIP-SiC matrix, difficulty in continuous transmission and load, and high defects, low crystallinity and impure composition of the matrix. SUMMARY

[0006] In view of the problems in the prior art, the present application mainly solves the problems that the PIP-SiC matrix is difficult to be continuously transmitted and carried, and the matrix has high defects, low crystallization degree and impure components. The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof f The present application introduces high volume fraction SiC into the interior of the fiber preform by using gel injection molding method, promotes the formation of continuous rigid skeleton in the interior of the matrix, and introduces nano-silicon powder modified polycarbosilane slurry into the interior of the SiC / SiC composite material by using vacuum impregnation and pressure impregnation method w The present application introduces high volume fraction SiC into the interior of the fiber preform by using gel injection molding method, promotes the formation of continuous rigid skeleton in the interior of the matrix, and introduces nano-silicon powder modified polycarbosilane slurry into the interior of the SiC / SiC composite material by using vacuum impregnation and pressure impregnation method f The present application introduces high volume fraction SiC into the interior of the fiber preform by using gel injection molding method, promotes the formation of continuous rigid skeleton in the interior of the matrix, and introduces nano-silicon powder modified polycarbosilane slurry into the interior of the SiC / SiC composite material by using vacuum impregnation and pressure impregnation method

[0007] The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof f The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof

[0008] The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof

[0009] The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof f The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof

[0010] The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof f The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof f The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof

[0011] The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof

[0012] The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof

[0013] The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof

[0014] The present application provides a SiC / SiC composite material with high-strength and high-modulus matrix, a preparation method and application thereof

[0015] The SiC whisker organic composite slurry is configured according to the following steps:

[0016] The SiC whisker, the pH regulator tetramethylammonium hydroxide is dissolved in deionized water, ball-milled for 2-4 h, mixed uniformly, the monomer acrylamide and the crosslinking agent methylene bisacrylamide are added and continue to be ball-milled and mixed for 5-10 h, and finally the initiator ammonium persulfate is added.

[0017] Preferably, the first polycarbosilane slurry is configured according to the following steps:

[0018] The solid-phase active filler silicon powder with a mass fraction of 10%-15% is added to the liquid-phase precursor, and the mixture is uniformly mixed to obtain the first polycarbosilane slurry; wherein the liquid-phase precursor is a mixture of vinyl-modified hydrogen polycarbosilane and dimethylbenzene, and the mass ratio of the vinyl-modified hydrogen polycarbosilane to the dimethylbenzene is 1:1-20; and the particle size of the solid-phase active filler silicon powder is 100-500 nm.

[0019] Preferably, the second polycarbosilane slurry is configured according to the following steps:

[0020] The solid-phase active filler silicon powder with a mass fraction of 5%-10% is added to the liquid-phase precursor, and the mixture is uniformly mixed to obtain the second polycarbosilane slurry; wherein the liquid-phase precursor is a mixture of vinyl-modified hydrogen polycarbosilane and dimethylbenzene, and the mass ratio of the vinyl-modified hydrogen polycarbosilane to the dimethylbenzene is 1:1-20; and the particle size of the solid-phase active filler silicon powder is 100-500 nm.

[0021] Preferably, the vacuum impregnation process comprises the following steps:

[0022] The porous composite material is placed in the impregnation device, vacuumized to a pressure lower than-0.09 MPa in the impregnation device, and kept for 20-30 min, then the porous composite material is immersed in the first polycarbosilane slurry or the second polycarbosilane slurry for 20-30 min and taken out.

[0023] Preferably, the pressure impregnation process comprises the following steps: the porous composite material is placed in a sealed container together with the first polycarbosilane slurry or the second polycarbosilane slurry, and pressurized to 1-3 MPa, kept for 30-60 min and taken out.

[0024] Preferably, the solidification and cracking process comprises the following steps:

[0025] The argon flow rate is 150 mL / min, and the temperature rising program is as follows: from room temperature to 220 ℃ at a rate of 10 ℃ / min, kept for 1 h, from 220 ℃ to 1100-1500 ℃ at a rate of 10 ℃ / min, kept for 2 h, and then cooled to 700 ℃ at a rate of 5 ℃ / min and naturally cooled;

[0026] This involves multiple impregnations and pyrolysis processes, with at least two impregnations and pyrolysis cycles.

[0027] Preferably, when preparing the CVI-BN interface phase in the SiC fiber preform using chemical vapor infiltration, BCl3 is used as the boron source, NH3 as the nitrogen source, H2 and Ar as dilution gases, the deposition temperature is 500~700 ℃, the pressure is 2~6 kPa, and the deposition time is 20~40 h; wherein, the thickness of the interface phase is 150~500 nm.

[0028] The second objective of this invention is to provide a SiC matrix containing high strength and high modulus. f / SiC composite material.

[0029] The third objective of this invention is to provide a SiC matrix containing high strength and high modulus. f Application of SiC composite materials in hot-end components of aero-engines.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] This invention provides a SiC matrix containing high strength and high modulus. f This invention relates to SiC composite materials, their preparation methods, and applications. Firstly, a BN interfacial phase is deposited within a fiber preform, followed by high-volume-fraction SiC. w Inert fillers are used to prepare SiC w Organic slurry is introduced into the fiber preform via gel casting. Then, polycarbosilane slurry modified with active filler silica powder is introduced into the porous composite material via vacuum impregnation and pressure impregnation. Densification is achieved through multiple rounds of impregnation and pyrolysis. w The introduction of silicon powder promotes the formation of a continuous rigid load-carrying framework, and significantly reduces the content of defects (cracks, pores, etc.) in the matrix, improving the crystallinity and purity of the PIP-SiC matrix. Through the synergistic effect of the two fillers, not only is a PIP-SiC matrix with high strength and high modulus obtained, but the internal stress generated during the PIP-SiC matrix preparation process is also improved. This invention solves the problem of preparing SiC using the PIP method. f / SiC composite materials address the problems of low matrix strength, low modulus, and poor load transfer efficiency, effectively improving SiC f Mechanical properties of SiC composite materials.

[0032] This invention utilizes a gel casting method to significantly improve the performance of SiC. w The amount of SiC introduced (volume fraction of 5-20 vol.%) and its uniform distribution promote the formation of a continuous rigid load-carrying framework in the matrix. wThe addition of [a specific ingredient] can reduce the susceptibility of the PIP-SiC matrix to cracks, increase the crack initiation energy of the PIP-SiC matrix, increase the crack propagation path, and effectively improve the [crack propagation] of SiC. f Matrix strength of / SiC composite materials.

[0033] This invention, by precisely controlling the amount and particle size of silicon powder introduced, can control the interaction between the active filler silicon powder and SiC. w The reaction process between residual carbon in the organic slurry and free carbon generated during PCS pyrolysis yields a pure PIP-SiC matrix, further enhancing the modulus of the PIP-SiC matrix.

[0034] The SiC grains generated by the silicon-carbon reaction provided by this invention are attached to SiC. w The surrounding area further reinforces the rigid framework inside the matrix, improving the load transfer performance of PIP-SiC.

[0035] The exothermic reaction of silicon-carbon provided by this invention can improve the crystallinity and grain size of SiC. SiC with high crystallinity and large grain size exhibits higher thermal conductivity and intrinsic strength than amorphous SiC, which helps to reduce SiC crystal size. f The influence of thermal stress on SiC composites in high-temperature applications, improving the performance of SiC... f Performance of / SiC composite materials.

[0036] The volume expansion effect during the silicon-carbon reaction process in this invention can, to a certain extent, suppress the stress generated by shrinkage during PCS pyrolysis, reducing matrix cracks and porosity. This is not only beneficial for improving the performance of SiC... f The overall density of the PIP-SiC composite material (porosity not exceeding 10%) is improved, and it also helps to improve the structural integrity of the PIP-SiC matrix, reduce the matrix defect content, and improve the overall modulus and matrix load transfer efficiency of the PIP-SiC matrix.

[0037] The silicon powder provided by this invention, as an active filler, has low raw material costs and a simple and easy-to-implement silicon powder introduction process, consistent with the advantages of the PIP method, such as low cost, simple process operation, and ability to manufacture complex-shaped components. The unmodified PIP process has low efficiency and a long densification cycle, requiring multiple rounds of impregnation and pyrolysis to achieve high densification. The addition of the two fillers in this invention can effectively shorten the PIP densification cycle, further reducing manufacturing costs. Attached Figure Description

[0038] Figure 1 This is a process flow diagram of the preparation method involved in the present invention.

[0039] Figure 2 PIP SiC containing a high-strength and high-modulus matrix f Schematic diagram of the SiC composite material structure.

[0040] Figure 3 SiC prepared for Example 2 by gel casting method w Scanning electron microscope image.

[0041] Figure 4 SiC prepared for Comparative Example 1 and Example 2 f Scanning electron microscope image of polished section of PIP-SiC matrix in / SiC composite.

[0042] Figure 5 Modified SiC prepared for Example 2 f Bending stress-displacement curve of / SiC composite.

[0043] Figure 6 Modified SiC prepared for Example 2 f Tensile stress-strain curve of / SiC composite. DETAILED DESCRIPTION

[0044] In order to make the technical personnel of the present application better understand the technical solutions can be implemented, the following specific embodiments and the present application is further described with reference to the drawings, but the examples are not as a limitation of the present application.

[0045] In order to solve the problem of low strength, low modulus and poor load transfer efficiency of the matrix of the composite material prepared by PIP method, the present application provides a kind of SiC f / SiC composite containing high strength and high modulus matrix. By jointly modifying PIP-SiC matrix with inert filler SiC w And active filler silicon powder, continuous rigid load transfer skeleton is formed in the matrix, and the defect content of the matrix is reduced, the crystallinity is improved, and the components are purified. The mechanical properties of the modified composite are improved by more than 30%.

[0046] In order to achieve the above purpose, the present application provides a kind of SiC f / SiC composite containing high strength and high modulus matrix, and a preparation method thereof, comprising the following steps:

[0047] CVI-BN interfacial phase is prepared in SiC fiber preform by chemical vapor infiltration process, and SiC whisker is introduced into SiC fiber preform by gel casting process, to obtain porous composite material;

[0048] The porous composite material is placed in the first polycarbosilane slurry for multiple times of impregnation and pyrolysis, to obtain semi-dense SiC f / SiC composite material;

[0049] The semi-dense SiC fThe / SiC composite material is placed in the second polycarbosilane slurry for multiple times of impregnation and pyrolysis to obtain dense SiC f / SiC composite material

[0050] Each impregnation and pyrolysis process comprises: placing the composite material in the first polycarbosilane slurry or the second polycarbosilane slurry, vacuum impregnation, pressure impregnation, and then curing and pyrolysis in an argon atmosphere; the mass fraction of fillers in the first polycarbosilane slurry is greater than that in the second polycarbosilane slurry.

[0051] The SiC whisker is introduced into the SiC fiber preform by the gel casting process, comprising:

[0052] The SiC whisker organic composite slurry is prepared;

[0053] After the SiC whisker organic composite slurry is degassed by vacuum stirring, it is poured into a mold containing the SiC fiber preform, and the SiC whisker organic composite slurry is uniformly dispersed in the SiC fiber preform by vibration; the mold is placed in an oven at 75-85 ℃ for 2-4 h for curing;

[0054] The SiC whisker organic composite slurry is prepared according to the following steps:

[0055] The SiC whisker, the pH adjuster tetramethylammonium hydroxide, the monomer acrylamide, and the crosslinking agent methylene bisacrylamide are dissolved in deionized water and ball milled for 2-4 h, and then the initiator ammonium persulfate is added.

[0056] The first polycarbosilane slurry is prepared according to the following steps:

[0057] The solid active filler silicon powder with a mass fraction of 10-15% is added to the liquid precursor, and the mixture is uniformly mixed to obtain the first polycarbosilane slurry; wherein the liquid precursor is a mixture of vinyl-modified hydrogen polycarbosilane and dimethylbenzene, and the mass ratio of vinyl-modified hydrogen polycarbosilane to dimethylbenzene is 1:1-20; the particle size of the solid active filler silicon powder is 100-500 nm.

[0058] The second polycarbosilane slurry is prepared according to the following steps:

[0059] The solid active filler silicon powder with a mass fraction of 5-10% is added to the liquid precursor, and the mixture is uniformly mixed to obtain the second polycarbosilane slurry; wherein the liquid precursor is a mixture of vinyl-modified hydrogen polycarbosilane and dimethylbenzene, and the mass ratio of vinyl-modified hydrogen polycarbosilane to dimethylbenzene is 1:1-20; the particle size of the solid active filler silicon powder is 100-500 nm.

[0060] The vacuum impregnation process comprises:

[0061] The porous composite is placed in the impregnation device, vacuumized to a pressure lower than -0.09 MPa in the impregnation device, and kept for 20-30 min, then the porous composite is immersed in the first polycarbosilane slurry or the second polycarbosilane slurry for 20-30 min and taken out.

[0062] The pressure impregnation process is: the porous composite is placed in a sealed container together with the first polycarbosilane slurry or the second polycarbosilane slurry, pressurized to 1-3 MPa, kept for 30-60 min, and taken out.

[0063] The solidification and cracking process comprises:

[0064] The argon flow rate is 150 mL / min, and the temperature rising program is: from room temperature to 220 ℃ at a rate of 10 ℃ / min, kept for 1 h, from 220 ℃ to 1100-1500 ℃ at a rate of 10 ℃ / min, kept for 2 h, and then cooled to 700 ℃ at a rate of 5 ℃ / min and naturally cooled.

[0065] The multiple impregnation and cracking is at least twice.

[0066] When the chemical vapor infiltration process is used to prepare the CVI-BN interface phase in the SiC fiber preform, BCl3 is used as the boron source, NH3 is used as the nitrogen source, H2 and Ar are used as the dilution gas, the deposition temperature is 500-700 ℃, the pressure is 2-6 kPa, and the deposition time is 20-40 h; wherein the thickness of the interface phase is 150-500 nm.

[0067] In an embodiment, referring to Figure 1 Fig. 1, a SiC / SiC composite material containing a high-strength and high-modulus matrix is prepared. f The preparation method of the SiC / SiC composite material comprises the following specific steps:

[0068] Step 1: a chemical vapor infiltration process is used to prepare a CVI-BN interface phase in the SiC fiber preform.

[0069] The fiber preform is one of a unidirectional SiC fiber preform, a two-dimensional SiC fiber preform, or a three-dimensional four-way SiC fiber preform, wherein the fiber volume fraction is 30%-50%.

[0070] The preparation process of the CVI-BN interface phase is a chemical vapor infiltration process, BCl3 is used as the boron source, NH3 is used as the nitrogen source, H2 and Ar are used as the dilution gas, the deposition temperature is 500-700 ℃, the pressure is 2-6 kPa, and the deposition time is 20-40 h; wherein the thickness of the interface phase is 150-500 nm.

[0071] Step 2: Prepare SiC whiskers (SiC w Organic slurry; SiC is introduced into the SiC fiber preform using a gel casting process. w SiC w With a volume fraction of 5%–20% in the composite material, a density of 1.9–2.1 g / cm³ is obtained. 3 Porous composite materials;

[0072] SiC w The method for preparing organic composite slurry is as follows: SiC w pH adjuster tetramethylammonium hydroxide (TMAH) was dissolved in deionized water, ball-milled for 2-4 hours, and mixed thoroughly to obtain SiC. w Organic slurry;

[0073] To SiC w The organic slurry was ball-milled with monomer acrylamide (AM) and crosslinking agent methylenebisacrylamide (MBAM) for 5–10 h; finally, ammonium persulfate (APS) initiator was added to obtain SiC. w Organic composite slurry; of which, SiC w The organic slurry formulation is as follows: SiC w The mass fraction is 30%~70%, the mass fraction of tetramethylammonium hydroxide is 1%~3%, the mass fraction of acrylamide is 3%~10%, the mass fraction of methylenebisacrylamide is 0.4%~1%, and the mass fraction of ammonium persulfate is 0.4%~1%.

[0074] The gel casting process is as follows: SiC w After being vacuum-stirred and defoamed, the organic slurry is poured into a mold containing fiber preforms, and the SiC is then vibrated to allow the slurry to dissolve. w The organic slurry is uniformly dispersed within the fiber preform; the mold is placed in an 80 ℃ oven for curing for 2-4 h, and finally the fiber preform is removed from the mold.

[0075] Step 3: Introduce SiC w The porous composite material was vacuum impregnated in polycarbosilane slurry (first polycarbosilane slurry) for 1 hour, then pressure impregnated in polycarbosilane slurry for 1 hour, and then sonicated for 10 minutes; the excess slurry on the surface of the composite material was wiped dry, and it was placed in a tube furnace for curing and pyrolysis in an argon atmosphere.

[0076] The preparation method of polycarbosilane slurry is as follows: 10%~15% by mass of solid active filler silicon powder is added to the liquid phase precursor. The liquid phase precursor is a mixture of vinyl-modified hydrogen polycarbosilane and xylene. The mass ratio of vinyl-modified hydrogen polycarbosilane to xylene is 1:20~1:1.

[0077] The vacuum impregnation process is as follows: the porous composite material is placed in the impregnation device, and a vacuum is drawn until the pressure inside the impregnation device is lower than -0.09 MPa. After maintaining this for 20 to 30 minutes, the porous composite material is immersed in polycarbosilane slurry and maintained for 20 to 30 minutes before being removed.

[0078] The pressure impregnation process is as follows: the porous composite material together with the polycarbosilane slurry is placed in a sealed container and pressurized at 1~3MPa for 30~60 min before being removed;

[0079] The solidification and pyrolysis process was as follows: the argon flow rate was 150 mL / min, the heating program was as follows: 10 ℃ / min from room temperature to 220 ℃, hold for 1 h, 10 ℃ / min from 220 ℃ to 1100~1500 ℃, hold for 2 h, 5 ℃ / min from 1100~1500 ℃ to 700 ℃ and then allow to cool naturally.

[0080] The solid filler silicon powder in step 3 has a particle size of 100~500 nm. Nanoscale silicon powder filler can accumulate around SiCw, interacting with SiC... w The organic matter in the organic slurry reacts with the residual carbon to form large-sized β-SiC grains, improving the matrix's carrying capacity.

[0081] Step 4: Remove the PIP debris adhering to the surface of the composite material, and repeatedly impregnate and pyrolyze it 2-5 times to obtain a density of 2.1-2.4 g / cm³. 3 Semi-dense SiC f / SiC composite materials;

[0082] Reduce the mass fraction of silicon powder filler in the polycarbosilane slurry (second polycarbosilane slurry), repeat step 3, and repeatedly impregnate and pyrolyze 2-5 times to obtain dense SiC. f / SiC composite material.

[0083] In step 4, the polycarbosilane slurry contains silicon powder with a mass fraction reduced to 5%–10%. w After the organic matter in the organic slurry completely reacts with the residual carbon, the silicon powder only reacts with the free carbon generated during the PCS pyrolysis process. In order to maintain the SiC phase in the PIP-SiC matrix close to the stoichiometry, the required silicon powder content is reduced.

[0084] A second aspect of the present invention provides a SiC matrix containing high strength and high modulus. f / SiC composite material.

[0085] See Figure 2 As shown, the SiC f / The interior of the SiC composite matrix is ​​composed of SiC wThe β-SiC grains with the grain size greater than 50 nm form a continuous rigid transmission skeleton, the skeleton surface is wrapped by a SiC filling phase with less defects (cracks and pores), a crystallinity greater than 80% and a near stoichiometric ratio, and the skeleton and the filling phase jointly form a PIP-SiC matrix with high strength and high modulus.

[0086] The PIP-SiC matrix in the composite material has a modulus greater than 280 GPa, the matrix cracking stress of the composite material is greater than 140 MPa, the density is greater than 2.6 g / cm 3 , and the open porosity is less than 10%.

[0087] The third aspect of the present application provides a SiC f / SiC composite material containing a high-strength and high-modulus matrix for application in a hot end part of an aero-engine.

[0088] It should be noted that the experimental methods used in the present application are conventional methods unless otherwise specified; the reagents and materials used are commercially available unless otherwise specified.

[0089] Example 1

[0090] Step 1 SiC f / SiC fiber preform

[0091] Step 1.1 weave SiC fibers to obtain a unidirectional fiber preform, and the fiber volume fraction is 35%.

[0092] Step 1.2 prepare a BN interface phase in the SiC fiber preform by using a chemical vapor infiltration process, wherein BCl3 is a boron source, NH3 is a nitrogen source, H2 and Ar are dilution gases, the deposition temperature is 600 ℃, the pressure is 4 kPa, and the deposition time is 40 h, and thus the BN interface phase obtained has a thickness of 300 nm.

[0093] Step 2 introduce SiC w :

[0094] Step 2.1 dissolve SiC w with a mass fraction of 45 wt.%, 1.5 wt.% of a pH adjuster tetramethylammonium hydroxide TMAH in deionized water, and add appropriate amount of zirconium oxide milling beads into a ball milling jar, and wet mill for 4 h.

[0095] Step 2.2 add monomer acrylamide AM with a mass fraction of 6 wt.% and crosslinking agent methylene bisacrylamide MBAM with a mass fraction of 0.5 wt.% into the SiC w organic slurry, and continue to ball mill for 10 h.

[0096] Step 2.3 add a catalyst into the SiCw The organic slurry with 0.5 wt.% of initiator ammonium persulfate was degassed by vacuum stirring, and then poured into the mold with the fiber preform inside. The SiC w The organic slurry was uniformly dispersed in the fiber preform; the mold was placed in an 80 °C oven for 3 h of curing. Finally, the fiber preform was taken out of the mold to obtain a porous composite material with a density of 2.09 g / cm 3 .

[0097] Step 3: Impregnation and pyrolysis of polycarbosilane slurry:

[0098] Step 3.1: The vinyl-modified hydrogen polycarbosilane and xylene were mixed uniformly at a mass ratio of 1:3, and magnetically stirred at room temperature for 20 min as a liquid precursor. Then, 10 wt.% of solid active filler silicon powder with a particle size of 100 nm was added to the liquid precursor, and magnetically stirred at room temperature for 20 min as a polycarbosilane slurry for impregnation.

[0099] Step 3.2: The porous composite material was placed in an impregnation device, and vacuumed to a pressure lower than -0.09 MPa in the impregnation device for 30 min. Then, the porous composite material was immersed in the polycarbosilane slurry for 30 min and taken out.

[0100] Step 3.3: The porous composite material together with the polycarbosilane slurry was placed in a sealed container and pressurized to 1 MPa for 60 min and then taken out.

[0101] Step 3.4: The porous composite material obtained in step 3.3 was wiped to remove the excess slurry on the surface, and then placed in a tube furnace for curing and pyrolysis in an argon atmosphere. The argon gas flow rate was 150 mL / min, the temperature was raised at a rate of 10 °C / min from room temperature to 220 °C, held for 1 h, then raised at a rate of 10 °C / min from 220 °C to 1100 °C, held for 1 h, and then cooled naturally from 1100 °C to 700 °C at a rate of 5 °C / min.

[0102] Step 4: Repeated impregnation and pyrolysis:

[0103] Step 4.1: The PIP slag attached to the surface of the composite material obtained in step 3 was removed, and the repeated impregnation and pyrolysis was performed for 3 cycles to obtain a semi-dense SiC 3 / SiC composite material with a density of 2.36 g / cm f .

[0104] Step 4.2: The mass fraction of silicon powder filler in the polycarbosilane slurry was reduced to 5 wt.%, and step 3 was repeated for 5 cycles of repeated impregnation and pyrolysis to obtain a dense SiC f / SiC composite material.

[0105] The density of the final SiC f / SiC composite was 2.69 g / cm 3 , and the open porosity was 5.44%. The PIP-SiC matrix in the SiC f / SiC composite prepared in this example had a modulus of 302.2 ± 17.4 GPa, a matrix cracking stress of 155.2 ± 11.1 MPa, a flexural strength of 1311.6 ± 115.2 MPa, a fracture toughness of 48.6 ± 6.1 MPa·m 1 / 2 , and a tensile strength of 630.7 ± 48.7 MPa.

[0106] Example 2

[0107] Step 1 Preparation of SiC f / SiC fiber preform

[0108] Step 1.1 Two-dimensional fiber preform was obtained by weaving SiC fibers. The fiber volume fraction was 35%.

[0109] Step 1.2 A BN interfacial phase was prepared in the SiC fiber preform by a chemical vapor infiltration process, in which BCl3 was the boron source, NH3 was the nitrogen source, H2 and Ar were the dilution gases, the deposition temperature was 600 °C, the pressure was 4 kPa, and the deposition time was 40 h. The BN interfacial phase obtained had a thickness of 300 nm.

[0110] Step 2 Gel casting process for introducing SiC w :

[0111] Step 2.1 SiC w with a mass fraction of 45 wt.%, 1.5 wt.% of a pH adjuster tetramethylammonium hydroxide (TMAH) was dissolved in deionized water, and an appropriate amount of zirconium oxide milling beads was added into a ball milling jar, and wet milling was performed for 4 h.

[0112] Step 2.2 Monomer acrylamide (AM) with a mass fraction of 6 wt.% and 0.5 wt.% of crosslinking agent methylene bisacrylamide (MBAM) were added to the SiC w organic slurry, and ball milling was continued for 10 h.

[0113] Step 2.3 0.5 wt.% of initiator ammonium persulfate was added to the SiC w organic slurry, and after vacuum stirring to remove bubbles, the SiC w organic slurry was poured into a mold containing the fiber preform, and the SiC 3porous composite material.

[0114] Step 3. Impregnation and pyrolysis of polycarbosilane slurry:

[0115] Step 3.1 The vinyl-modified hydrogen polycarbosilane and xylene were mixed uniformly at a mass ratio of 1:3, and magnetically stirred at room temperature for 20 min as a liquid precursor. Then, 10 wt.% of solid active filler silicon powder with a particle size of 100 nm was added to the liquid precursor, and magnetically stirred at room temperature for 20 min as a polycarbosilane slurry for impregnation.

[0116] Step 3.2 The porous composite material was placed in an impregnation device, and vacuumized to a pressure lower than -0.09 MPa in the impregnation device for 30 min. Then, the porous composite material was immersed in the polycarbosilane slurry for 30 min and taken out.

[0117] Step 3.3 The porous composite material was placed in a sealed container together with the polycarbosilane slurry, and pressurized to 1 MPa for 60 min and taken out.

[0118] Step 3.4 The porous composite material obtained in step 3.3 was wiped to remove the excess slurry on the surface, and placed in a tube furnace for solidification and pyrolysis in an argon atmosphere. The argon gas flow rate was 150 mL / min, the temperature was raised at a rate of 10 ℃ / min from room temperature to 220 ℃, maintained for 1 h, raised at a rate of 10 ℃ / min from 220 ℃ to 1100 ℃, maintained for 1 h, and then cooled to 700 ℃ at a rate of 5 ℃ / min and naturally cooled.

[0119] Step 4. Repeated impregnation and pyrolysis:

[0120] Step 4.1 The PIP slag attached to the surface of the composite material obtained in step 3 was removed, and repeated impregnation and pyrolysis was performed for 4 cycles to obtain a semi-dense SiC 3 / SiC composite material with a density of 2.32 g / cm f .

[0121] Step 4.2 The mass fraction of silicon powder filler in the polycarbosilane slurry was reduced to 5 wt.%, and step 3 was repeated for 5 cycles to obtain a dense SiC f / SiC composite material.

[0122] The density of the final SiC f / SiC composite material was measured by the Archimedes drainage method to be 2.64 g / cm 3 , and the open porosity was 6.21%. The SiC fThe PIP-SiC matrix of / SiC composite has a modulus of 327.7 ± 11.9 GPa, a matrix cracking stress of 167.7 ± 8.3 MPa, a flexural strength of 857.1 ± 36.2 MPa, and a fracture toughness of 43.9 ± 3.1 MPa·m 1 / 2 , and a tensile strength of 492.8 ± 22.2 MPa.

[0123] Example 3

[0124] Step 1 SiC f Preparation of / SiC fiber preform

[0125] Step 1.1 Weaving SiC fibers to obtain a three-dimensional four-directional fiber preform. The fiber volume fraction is 35%.

[0126] Step 1.2 Preparing a BN interfacial phase in the SiC fiber preform by a chemical vapor infiltration process, wherein BCl3 is a boron source, NH3 is a nitrogen source, H2 and Ar are dilution gases, the deposition temperature is 600 ℃, the pressure is 4 kPa, and the deposition time is 40 h, thereby obtaining a BN interfacial phase with a thickness of 300 nm.

[0127] Step 2 Gel casting process for introducing SiC w :

[0128] Step 2.1 Dissolving 45 wt.% of SiC w , 1.5 wt.% of pH adjuster tetramethylammonium hydroxide TMAH in deionized water, adding an appropriate amount of zirconium oxide milling beads into a ball milling jar, and wet milling for 4 h.

[0129] Step 2.2 Adding 6 wt.% of monomer acrylamide AM and 0.5 wt.% of crosslinking agent methylene bisacrylamide MBAM to the SiC w organic slurry, and continuing to ball mill for 10 h.

[0130] Step 2.3 Adding 0.5 wt.% of initiator ammonium persulfate to the SiC w organic slurry, vacuum stirring to remove bubbles, pouring into a mold containing the fiber preform, and vibrating to uniformly disperse the SiC w organic slurry inside the fiber preform; placing the mold in an 80 ℃ oven for curing for 3 h. Finally, removing the fiber preform from the mold to obtain a porous composite material with a density of 2.02 g / cm 3 .

[0131] Step 3 Impregnation and pyrolysis of polycarbosilane slurry:

[0132] Step 3.1 The vinyl-modified hydridopolycarbosilane and xylene were mixed uniformly at a mass ratio of 1:3, and magnetically stirred at room temperature for 20 min as a liquid precursor. Then, 10 wt.% solid active filler silicon powder with a particle size of 100 nm was added to the liquid precursor, and magnetically stirred at room temperature for 20 min as a polycarbosilane slurry for impregnation.

[0133] Step 3.2 The porous composite material was placed in an impregnation device, and vacuumized to a pressure lower than -0.09 MPa in the impregnation device, and maintained for 30 min. Then, the porous composite material was immersed in the polycarbosilane slurry for 30 min, and taken out.

[0134] Step 3.3 The porous composite material was placed in a sealed container together with the polycarbosilane slurry, and pressurized to 1 MPa, and maintained for 60 min, and taken out.

[0135] Step 3.4 The porous composite material obtained in step 3.3 was wiped to remove the excess slurry on the surface, and placed in a tube furnace for curing and pyrolysis in an argon atmosphere. The argon flow rate was 150 mL / min, the temperature was raised at a rate of 10 ℃ / min from room temperature to 220 ℃, maintained for 1 h, raised at a rate of 10 ℃ / min from 220 ℃ to 1100 ℃, maintained for 1 h, and then cooled to 700 ℃ at a rate of 5 ℃ / min, and naturally cooled.

[0136] Step 4 Repeated impregnation and pyrolysis:

[0137] Step 4.1 The PIP slag attached to the surface of the composite material obtained in step 3 was removed, and repeated impregnation and pyrolysis was performed for 4 cycles to obtain a semi-dense SiC 3 / SiC composite material with a density of 2.34 g / cm f .

[0138] Step 4.2 The mass fraction of silicon powder filler in the polycarbosilane slurry was reduced to 5 wt.%, and step 3 was repeated for 5 cycles to obtain a dense SiC f / SiC composite material.

[0139] The density of the final SiC f / SiC composite material was measured by the Archimedes drainage method to be 2.65 g / cm 3 , and the open porosity was 6.12%. The SiC f / SiC composite material prepared in this example had a PIP-SiC matrix modulus of 296.5±3.8 GPa, a matrix cracking stress of 156.3±9.6 MPa, a bending strength of 846.5±48.8 MPa, and a fracture toughness of 45.2±2.4 MPa·m 1 / 2, the tensile strength is 470.8 ± 59.7 MPa.

[0140] Comparative Example 1

[0141] Step 1 SiC f Preparation of SiC fiber preform

[0142] Step 1.1 Weave SiC fibers to obtain a two-dimensional fiber preform. The fiber volume fraction is 35%.

[0143] Step 1.2 Prepare a BN interfacial phase in the SiC fiber preform by a chemical vapor infiltration process, wherein BCl3 is the boron source, NH3 is the nitrogen source, H2 and Ar are the dilution gases, the deposition temperature is 600 ℃, the pressure is 4 kPa, and the deposition time is 40 h, thereby obtaining a BN interfacial phase with a thickness of 300 nm.

[0144] Step 2 Impregnation and pyrolysis of polycarbosilane solution:

[0145] Step 2.1 Mix the vinyl-modified hydrogen polycarbosilane and xylene uniformly at a mass ratio of 1:3, and magnetically stir at room temperature for 20 min as the polycarbosilane solution.

[0146] Step 2.2 Put the porous composite material into the impregnation device, vacuumize to a pressure lower than -0.09 MPa in the impregnation device, and keep for 30 min, then immerse the porous composite material in the polycarbosilane solution for 30 min and take it out.

[0147] Step 2.3 Put the porous composite material together with the polycarbosilane solution into a sealed container and pressurize to 1 MPa, keep for 60 min and take it out.

[0148] Step 2.4 Wipe off the excess solution on the surface of the porous composite material obtained in step 2.3, put it into a tube furnace, and solidify and pyrolyze under an argon atmosphere, with an argon gas flow rate of 150 mL / min, a temperature rising program of 10 ℃ / min from room temperature to 220 ℃, holding for 1 h, 10 ℃ / min from 220 ℃ to 1100 ℃, holding for 1 h, and 5 ℃ / min from 1100 ℃ to 700 ℃, and then natural cooling.

[0149] Step 3 Repeated impregnation and pyrolysis:

[0150] Remove the PIP slag attached to the surface of the composite material obtained in step 2, and repeat the impregnation and pyrolysis for 15 cycles to obtain a dense SiC 3 / SiC composite material with a density of 2.65 g / cm f .

[0151] The final SiC fThe density of the SiC / SiC composite material is 2.65 g / cm 3 The open porosity of the SiC / SiC composite material is 6.01%. The SiC f The matrix modulus of the SiC / SiC composite material PIP-SiC is 207.1 ± 8.3 GPa, the matrix cracking stress is 110.1 ± 5.9 MPa, the flexural strength is 505.1 ± 76.8 MPa, and the fracture toughness is 22.2 ± 3.1 MPa·m 1 / 2 The tensile strength is 246.2 ± 36.7 MPa.

[0152] Figure 4 The photos show the cross-sectional morphology of the PIP-SiC matrix of the composite material before and after modification in Example 2 and Comparative Example 1. In Comparative Example 1, a large number of cracks and hole defects exist in the PIP-SiC matrix, which seriously affects the load transmission efficiency of the matrix. The matrix modulus, matrix cracking stress and mechanical properties of the composite material are all much lower than those of the modified composite material. Moreover, before modification, the PIP process impregnation furnace times are more (15 times), and the composite material preparation cycle is long.

[0153] Comparative Example 2

[0154] Step 1 SiC f Preparation of SiC / SiC fiber preform

[0155] Step 1.1 Weave SiC fibers to obtain a two-dimensional fiber preform. The fiber volume fraction is 35%.

[0156] Step 1.2 Prepare a BN interfacial phase in the SiC fiber preform by chemical vapor infiltration process, wherein BCl3 is the boron source, NH3 is the nitrogen source, H2 and Ar are the dilution gases, the deposition temperature is 600 ℃, the pressure is 4 kPa, and the deposition time is 40 h. The BN interfacial phase obtained by this method has a thickness of 300 nm.

[0157] Step 2 Gel casting process to introduce SiC w

[0158] Step 2.1 Dissolve 45 wt.% of SiC w , 1.5 wt.% of pH adjuster tetramethylammonium hydroxide TMAH in deionized water, add appropriate amount of zirconium oxide milling beads, and put them into a ball mill jar together. Wet mill for 4 h.

[0159] Step 2.2 Add 6 wt.% of monomer acrylamide AM and 0.5 wt.% of crosslinking agent methylene bisacrylamide MBAM to the SiC w organic slurry, and continue ball milling for 10 h.

[0160] Step 2.3 Add 0.5 wt.% of catalyst 2,2'-azobis(2-methylpropionitrile) AIBN to the SiC​w The organic slurry with 0.5 wt.% of initiator ammonium persulfate was poured into the mold with the fiber preform inside after vacuum stirring to remove bubbles, and the SiC w The organic slurry was uniformly dispersed inside the fiber preform; the mold was placed in an 80℃ oven for 3 h of curing. The fiber preform was finally taken out of the mold to obtain a porous composite material with a density of 2.08 g / cm 3 .

[0161] Step 3: Impregnation and pyrolysis of polycarbosilane solution:

[0162] Step 3.1: The vinyl-modified hydrogen polycarbosilane and xylene were mixed uniformly at a mass ratio of 1:3, and magnetically stirred at room temperature for 20 min as the polycarbosilane solution.

[0163] Step 3.2: The porous composite material was placed in the impregnation device, vacuumed to a pressure lower than -0.09 MPa in the impregnation device for 30 min, then immersed in the polycarbosilane solution for 30 min and taken out.

[0164] Step 3.3: The porous composite material was placed in a sealed container together with the polycarbosilane solution, pressurized to 1 MPa for 60 min and taken out.

[0165] Step 3.4: The porous composite material obtained in step 3.3 was wiped to remove excess solution on the surface, placed in a tube furnace for curing and pyrolysis in an argon atmosphere, with an argon gas flow rate of 150 mL / min, a temperature rising program of 10 ℃ / min from room temperature to 220 ℃, holding for 1 h, 10 ℃ / min from 220 ℃ to 1100 ℃, holding for 1 h, and 5 ℃ / min from 1100 ℃ to 700 ℃, and then naturally cooled.

[0166] Step 4: Repeated impregnation and pyrolysis:

[0167] Step 4.1: The PIP slag attached to the surface of the composite material obtained in step 3 was removed, and the repeated impregnation and pyrolysis was performed for 8 cycles to obtain a dense SiC 3 / SiC composite material with a density of 2.61 g / cm f .

[0168] The density of the final SiC f / SiC composite material was measured by the Archimedes drainage method to be 2.61 g / cm 3 , and the open porosity was 7.29%. The SiC fThe PIP-SiC matrix of the / SiC composite has a modulus of 248.5 ± 13.2 GPa, a matrix cracking stress of 119.2 ± 8.1 MPa, a bending strength of 506.1 ± 84.1 MPa, and a fracture toughness of 23.6 ± 2.5 MPa·m 1 / 2 , and a tensile strength of 265.4 ± 13.2 MPa.

[0169] SiC w After the addition of SiC w , a continuous skeleton structure is formed inside the PIP-SiC matrix, and the modulus and matrix cracking stress of the PIP-SiC matrix of the composite are improved compared with the unmodified composite. However, the PIP-SiC matrix near the SiC w still has problems such as high defect content, low crystallinity, and impure composition. Therefore, it is difficult to efficiently improve the mechanical properties of the composite by only adding SiC w as a filler.

[0170] Comparative Example 3

[0171] Step 1 SiC f Preparation of the / SiC fiber preform

[0172] Step 1.1 Weaving SiC fibers to obtain a two-dimensional fiber preform. The fiber volume fraction is 35%.

[0173] Step 1.2 Using a chemical vapor infiltration process to prepare a BN interfacial phase in the SiC fiber preform, wherein BCl3 is the boron source, NH3 is the nitrogen source, H2 and Ar are the dilution gases, the deposition temperature is 600 ℃, the pressure is 4 kPa, and the deposition time is 40 h. The BN interfacial phase obtained has a thickness of 300 nm.

[0174] Step 2 Impregnation and pyrolysis of polycarbosilane slurry:

[0175] Step 2.1 Mixing vinyl-modified hydrogen polycarbosilane and xylene uniformly at a mass ratio of 1:3 at room temperature for 20 min as the liquid precursor. Then, adding 5 wt.% of solid active filler silicon powder with a particle size of 100 nm into the liquid precursor and stirring magnetically at room temperature for 20 min as the polycarbosilane slurry for impregnation.

[0176] Step 2.2 Placing the porous composite into an impregnation device, vacuumizing to a pressure lower than -0.09 MPa in the impregnation device, and keeping for 30 min. Then, immersing the porous composite into the polycarbosilane slurry for 30 min and taking it out.

[0177] Step 2.3 Placing the porous composite together with the polycarbosilane slurry into a sealed container and pressurizing to 1 MPa, keeping for 60 min and then taking it out.

[0178] Step 2.4 Wipe off the excess slurry on the surface of the porous composite material obtained in Step 2.3, place it in a tube furnace, and solidify and pyrolyze it in an argon atmosphere. The argon flow rate is 150 mL / min, and the heating program is as follows: heat from room temperature to 220 ℃ at 10 ℃ / min, hold for 1 h, heat from 220 ℃ to 1100 ℃ at 10 ℃ / min, hold for 1 h, and then cool from 1100 ℃ to 700 ℃ at 5 ℃ / min and then allow it to cool naturally.

[0179] Step 3: Repeated immersion pyrolysis:

[0180] After removing the PIP debris adhering to the surface of the composite material obtained in step 2, the mixture was repeatedly impregnated and pyrolyzed 11 times to obtain a density of 2.62 g / cm³. 3 dense SiC f / SiC composite material.

[0181] The final SiC was measured using the Archimedes displacement method. f The density of the SiC composite material is 2.62 g / cm³. 3 The porosity is 5.93%. The SiC prepared in this embodiment... f The PIP-SiC matrix of the / SiC composite material has a matrix modulus of 234.7±11.7 GPa, a matrix cracking stress of 123.4±6.2 MPa, a flexural strength of 591.2±78.3 MPa, and a fracture toughness of 28.3±2.2 MPa·m. 1 / 2 The tensile strength is 302.8 ± 28.5 MPa.

[0182] After adding silicon powder, the number of cracks and pores inside the PIP-SiC matrix of the composite material decreased, the crystallinity of SiC increased, and the SiC phase in the matrix approached the stoichiometry. The modulus, cracking stress, and mechanical properties of the composite material were all improved after adjustment. However, the PIP process involved multiple impregnation and pyrolysis furnace cycles (11 times), resulting in a loosely distributed PIP-SiC matrix and the lack of a continuous rigid framework within the matrix, making continuous load transfer difficult. Therefore, simply adding silicon powder as a filler is insufficient to efficiently improve the mechanical properties of the composite material.

[0183] To illustrate the SiC containing a high-strength and high-modulus matrix provided by the present invention f The relevant properties of the / SiC composite material are explained with reference to the attached figures.

[0184] Figure 3 In Example 2, SiC was introduced into the fiber preform using a gel casting method. w Scanning electron microscope image.

[0185] from Figure 3It can be seen that SiC w It presents long rod shape, diameter is between 1-2 μm, length is 10-30 μm. SiC w It is mutually overlapped and stacked between the pores, forming a three-dimensional network skeleton structure, which is beneficial to the subsequent matrix transmission. The pore size of the preform is mostly between 1-3 μm, and the subsequent PIP process is used to fill the pores.

[0186] Figure 4 SiC f PIP-SiC matrix in the / SiC composite material.

[0187] From Figure 4 It can be seen that there are a large number of cracks and hole defects in the PIP-SiC matrix in Comparative Example 1, and the crack size is about 10-40 μm. These defects are difficult to fill by repeated impregnation and pyrolysis. The PIP-SiC matrix in Example 2 is smooth and flat, and only a small amount of cracks exist, which is expected to improve the modulus of the matrix and the mechanical properties of the composite material.

[0188] Figure 5 Modified SiC f Bending stress-displacement curve of / SiC composite material.

[0189] From Figure 5 It can be seen that the SiC f / SiC composite material prepared in Example 2 can reach 857 MPa, which is much higher than the bending strength of the traditional PIP process prepared SiC f / SiC composite material. And after the composite material reaches the maximum load, the load decreases in steps, showing pseudo-plastic fracture.

[0190] Figure 6 Modified SiC f Tensile stress-strain curve of / SiC composite material.

[0191] Figure 6 It can be seen that the SiC f / SiC composite material prepared in Example 2 can reach 493 MPa, using 0.005% strain offset method, the proportional limit stress of SiC f / SiC composite material is 167 MPa, which significantly improves the tensile strength and proportional limit stress of the traditional PIP process prepared SiC f / SiC composite material.

[0192] The preferred embodiments are described herein, including the best mode known to the inventors of practicing the application. Of course, variations on the preferred embodiments will occur to those of ordinary skill in the art once advised of the application in general, and the preferred embodiments in particular, without departing from the spirit and scope of the application. Therefore, it is well within the framewofk of the application to have other embodiments that are built upon the preferred embodiments and that can be missing, plus additional structures and / or functions. Accordingly, the appended claims are intended to encompass within their scope all alternatives, modifications, permutations, and variations of the preferred embodiments that have been described herein but also which can be apparent to those of ordinary skill in the art once advised of the application in general, and the preferred embodiments in particular. The following examples are provided to further illustrate the application, but should not be construed as limiting the scope of the application.

[0193] While the application has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, since the scope of the application is indicated by the appended claims, along with their equivalents.

Claims

1. A SiC matrix containing high strength and high modulus f The method for preparing / SiC composite materials is characterized by, The method comprises the following steps: The CVI-BN interface phase is prepared in the SiC fiber preform by a chemical vapor infiltration process, and SiC whiskers are introduced into the SiC fiber preform by a gel casting process to obtain a porous composite material; The porous composite is placed in a first polycarbosilane slurry for multiple impregnations and pyrolysis to obtain a semi-dense SiC f / SiC composite The semi-dense SiC f / SiC composite was placed in a second polycarbosilane slurry for multiple impregnations and pyrolysis to obtain a dense SiC f / SiC composite; Each time of impregnation and pyrolysis comprises: placing the composite material in the first polycarbosilane slurry or the second polycarbosilane slurry, vacuum impregnation, pressure impregnation, and then pyrolysis in an argon atmosphere; the mass fraction of fillers in the first polycarbosilane slurry is greater than that in the second polycarbosilane slurry; The method for introducing SiC whiskers into the SiC fiber preform by the gel casting process comprises the following steps: An SiC whisker organic composite slurry is prepared; The SiC whisker organic composite slurry is poured into a mold containing the SiC fiber preform after vacuum stirring and defoaming, and the SiC whisker organic composite slurry is uniformly dispersed in the SiC fiber preform by vibration; the mold is placed in an oven at 75-85 ℃ for 2-4 h for curing; The SiC whisker organic composite slurry is prepared by the following steps: SiC whiskers and a pH regulator tetramethylammonium hydroxide are dissolved in deionized water, ball-milled for 2-4 h, mixed uniformly, monomer acrylamide and crosslinking agent methylene bisacrylamide are added and ball-milled for 5-10 h, and finally initiator ammonium persulfate is added; The first polycarbosilane slurry is prepared by the following steps: 10%-15% of solid-phase active fillers silicon powder is added to a liquid precursor, and the mixture is uniformly mixed to obtain the first polycarbosilane slurry; the liquid precursor is a mixture of vinyl-modified hydrogen polycarbosilane and dimethylbenzene, and the mass ratio of vinyl-modified hydrogen polycarbosilane to dimethylbenzene is 1:1-20; the particle size of the solid-phase active fillers silicon powder is 100-500 nm; The second polycarbosilane slurry is prepared by the following steps: 5%-10% of solid-phase active fillers silicon powder is added to a liquid precursor, and the mixture is uniformly mixed to obtain the second polycarbosilane slurry; the liquid precursor is a mixture of vinyl-modified hydrogen polycarbosilane and dimethylbenzene, and the mass ratio of vinyl-modified hydrogen polycarbosilane to dimethylbenzene is 1:1-20; the particle size of the solid-phase active fillers silicon powder is 100-500 nm; The pyrolysis process comprises: the argon flow is 150 mL / min, the temperature rising program is: from room temperature to 220 ℃ at a rate of 10 ℃ / min, holding for 1 h, from 220 ℃ to 1100-1500 ℃ at a rate of 10 ℃ / min, holding for 2 h, and then natural cooling from 1100-1500 ℃ to 700 ℃ at a rate of 5 ℃ / min; the impregnation and pyrolysis are performed at least twice. When the CVI-BN interface phase is prepared in the SiC fiber preform by a chemical vapor infiltration process, BCl3 is used as a boron source, NH3 is used as a nitrogen source, H2 and Ar are used as dilution gases, the deposition temperature is 500-700 ℃, the pressure is 2-6 kPa, and the deposition time is 20-40 h; the thickness of the interface phase is 150-500 nm.

2. SiC composite material containing a high-strength and high-modulus matrix according to claim 1 f A method for producing an SiC composite material containing a high-strength and high-modulus matrix, characterized by, The vacuum impregnation process comprises: placing the porous composite into an impregnation device, vacuumizing to a pressure lower than-0.09 MPa in the impregnation device, keeping for 20-30 min, then immersing the porous composite into the first polycarbosilane slurry or the second polycarbosilane slurry for 20-30 min, and taking out.

3. The SiC composite material containing a high-strength and high-modulus matrix according to claim 1 f A method for producing a SiC composite material, characterized by, The pressure impregnation process comprises: placing the porous composite together with the first polycarbosilane slurry or the second polycarbosilane slurry into a closed container, pressurizing to 1-3 MPa, keeping for 30-60 min, and taking out.

4. A SiC composite material containing a high strength and high modulus matrix produced by the method of any one of claims 1 to 3. f / SiC composite material.

5. A SiC composite material containing high strength and high modulus matrix as claimed in claim 4 for use in hot section components of aircraft engines. f / SiC composite material in hot section components of aircraft engines.

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