A boron-containing mesophase-assisted low-temperature preparation of water-oxygen resistant matrix modified SiC f / SiC composite material, method for preparing the same, and use thereof

Abstract

This invention discloses a method for low-temperature preparation of water-resistant, oxygen-resistant bulk modified SiC with boron-containing mesophase assistance. f This paper relates to the field of composite materials technology, specifically SiC composite materials, their preparation methods, and applications. The method includes the preparation of porous SiC... f / SiC composite material; obtain boron-containing resin precursor solution; porous SiC f After immersing the SiC composite material in a boron-containing resin precursor solution, a cured composite is obtained. The cured composite is then held at 900–1100℃ for 2–4 hours to obtain a pyrolysis composite. This pyrolysis composite is then coated with Y-Si powder and further wrapped with graphite paper. Finally, it undergoes a reaction melt infiltration process under vacuum at 1260–1300℃ for 10–30 minutes to obtain water-resistant, oxygen-modified SiC. f / SiC composite materials. This invention utilizes mesophase-assisted preparation of modified SiC. f / SiC composite materials, on the one hand, reduce the preparation temperature and reduce fiber damage; on the other hand, they avoid the premature appearance of the low-temperature Y-Si phase and improve the ultimate service temperature of the composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of composite materials, and particularly relates to a boron-containing interphase assisted low-temperature preparation of a water-oxygen resistant matrix modified SiC f / SiC composite material and a preparation method and application thereof. BACKGROUND

[0002] Continuous silicon carbide fiber reinforced silicon carbide ceramic matrix composite (SiC f / SiC composite material) is known as the next generation of aero-engine thermal structural material due to its high-temperature resistance, high specific strength and many other advantages. With the continuous increase of the flight speed of aircraft and the continuous maturity of the preparation technology of SiC f / SiC composite material, the application demand of SiC f / SiC composite material components has been expanded from a low-temperature and low-load environment (below 1200 DEG C, tensile strength of about 150 MPa) to a medium-temperature and medium-load environment (1200-1500 DEG C, tensile strength greater than 200 MPa). Higher service temperature and stress conditions make the corrosion of SiC f / SiC composite material components more serious, and it is urgent to develop an advanced process to prepare a high-temperature resistant, high-load and corrosion resistant SiC f / SiC composite material.

[0003] High-density materials generally have high matrix cracking stress, can meet the requirements of high performance (tensile strength greater than 200 MPa), and in a dry oxygen environment, the dense oxide layer (SiO2) generated by the surface oxidation of high-density SiC f / SiC composite material can effectively prevent the diffusion of oxygen to the inside of the material. However, in a water-oxygen environment, the SiO2 layer will react with water to make the oxide layer be consumed, and oxygen will further corrode the SiC f / SiC composite material after contacting. Therefore, it is urgent to introduce a water-oxygen resistant element (yttrium, ytterbium, etc.) into the matrix of SiC f / SiC composite material to improve its water-oxygen resistance. Since the strength of the water-oxygen resistant element phase itself is low, and there is a difference between its thermal expansion coefficient and SiC, which will cause thermal residual stress in the composite material, the introduction of the water-oxygen resistant element phase will generally reduce the mechanical properties of SiC f / SiC composite material. In addition, when the water-oxygen resistant element cannot form a dense layered structure, the unprotected SiC matrix will still be corroded by water and oxygen.

[0004] The reaction melt infiltration (RMI) process has the characteristics of short cycle, high density of the prepared composite material and excellent mechanical properties, and is the preferred method for preparing a water-oxygen resistant matrix modified SiC f / SiC composite material. In the prior art, graphite particles are introduced into porous SiCf / SiC composite, then Y-Si alloy was infiltrated into the porous composite at 1350℃ to prepare SiC f / SiC-SiYC composite, the composite has a high density, due to the reaction of Si in Y-Si alloy with graphite, the alloy component shifts to the direction of high Y content, resulting in the need to prepare SiC at 100℃ higher than the melting point of Y-Si alloy (1242℃) f / SiC-SiYC composite, which may cause certain thermal damage to SiC fibers that lack sufficient temperature resistance. In addition, due to the use of vacuum and pressure impregnation to introduce carbon sources, it is difficult to control the content and distribution of carbon, and there is a high content of residual alloy in the composite, and the distribution of SiC and water-oxygen resistant phases generated by reaction is not uniform.

[0005] The skilled person introduces boron carbide particles into the porous SiC f / SiC composite by vacuum and pressure impregnation, and then uses Y-Si alloy to react and infiltrate at 1300, 1400 and 1500℃, respectively, above the melting point of the alloy (1242℃) to prepare SiC f / Si-Y-B-C composite. Due to the introduction of boron element, the composite has a certain self-healing ability. The introduction of carbon and boron elements still adopts the idea of hard particle slurry, and it is difficult to control the content and distribution of boron carbide, there is a high content of residual alloy in the composite, and the distribution of SiC and water-oxygen resistant phases generated by reaction is not uniform, showing the morphology of residual alloy wrapped by reaction generated phases.

[0006] As can be seen, the carbon introduced by hard slurry is difficult to make the composite obtain water-oxygen resistant phase uniform distribution matrix, and due to the difficulty in controlling the content of carbon and boron, there is also a large amount of unreacted low melting point alloy (melting point 1242℃) in the matrix, affecting the high temperature application of the composite.

[0007] In addition, in the prior art, boric acid, polyvinyl alcohol, glycerol and water are mixed to prepare a sol by 120℃ oil bath for 4~8h, the sol is introduced into the carbon fiber preform, and the gel is cracked after 18~24h, then repeated impregnation and cracking 8~16 times to obtain C f / B4C-C composite, and then C f / SiC-ZrC-ZrB2 ultra-high temperature ceramic matrix composite material, the composite material is relatively dense, but cannot resist water oxygen corrosion. In the sol-gel process stage, the preparation process of the sol containing boric acid and polyvinyl alcohol and the gelation time are long, and long-time drying and repeated immersion and pyrolysis 8-16 times can meet the requirements of composite infiltration; in addition, the polyboron ethyl ester gel prepared by the method is a coated structure, and the carbon and boron carbide formed by the carbon thermal reduction reaction reproduce the distribution characteristics of the gel, that is, the coated distribution in the pores of the / SiC composite material, resulting in the coated distribution of the SiC phase generated by the reaction after infiltration. f / SiC composite material. SUMMARY

[0008] In view of the problems in the background art, the present application mainly aims at the problem that the carbon introduced by the hard slurry in the prior art is difficult to make the composite material obtain the water-oxygen-resistant matrix with uniform distribution, and due to the difficulty in regulating the content of carbon and boron, there is a large amount of unreacted low-melting-point alloy (melting point 1242℃) in the matrix, which affects the high-temperature application of the composite material. The present application provides a boron-containing interphase assisted low-temperature preparation of water-oxygen-resistant matrix modified SiC f / SiC composite material and its preparation method and application. The method uses an interphase to assist in the preparation of modified SiC f / SiC composite material, on the one hand, reduces the preparation temperature and reduces the damage to the fibers; on the other hand, avoids the early appearance of low-temperature Y-Si phase, and improves the ultimate use temperature of the composite material.

[0009] The first object of the present application is to provide a boron-containing interphase assisted low-temperature preparation of water-oxygen-resistant matrix modified SiC f / SiC composite material, comprising the following steps:

[0010] Preparation of porous SiC f / SiC composite material;

[0011] Disperse furfuryl alcohol and triblock copolymer in an ethanol aqueous solution to obtain a mixed solution I;

[0012] Disperse ammonium borate hexahydrate in a 37wt.% formaldehyde aqueous solution to obtain a mixed solution II;

[0013] Mix the mixed solution I and the mixed solution II, then add 25wt.% ammonia water, and mix uniformly to obtain a boron-containing resin precursor solution;

[0014] Immerse the porous SiC f / SiC composite material in the boron-containing resin precursor solution, and then perform a curing treatment to obtain a cured composite;

[0015] The solidified composite is kept at 900-1100 ℃ for 2-4 hours under the protection of inert gas to obtain a pyrolyzed composite;

[0016] The pyrolyzed composite is wrapped with Y-Si powder and wrapped with graphite paper on the outermost layer, and then subjected to reactive melt infiltration at 1260-1300 ℃ under vacuum for 10-30 min to obtain the water-oxygen resistant matrix modified SiC f / SiC composite material.

[0017] Preferably, the mass ratio of the furfuryl alcohol and the triblock copolymer is 3-12:1; and the mass ratio of the ammonium borate hexahydrate and the 37wt.% aqueous formaldehyde solution is 1:1.5-5.

[0018] Preferably, the aqueous ethanol solution is prepared by mixing the water solvent and the anhydrous ethanol at a volume ratio of 1:0.75-5.

[0019] Preferably, the solidification treatment comprises:

[0020] The porous SiC f / SiC composite material is immersed in the boron-containing resin precursor solution, heated to 80-150 ℃ at a heating rate of 3-5 ℃ / min in a curing kettle, pressurized to 1.5-3 MPa, kept for 2-12 hours, and then dried at 80-120 ℃ in an air environment for 20-40 min.

[0021] Preferably, the porous SiC f / SiC composite material is immersed in the boron-containing resin precursor solution, which comprises: f The porous SiC f / SiC composite material and the boron-containing resin precursor solution are placed in a container, vacuumized to a pressure of <0.09 MPa in the container, kept for 20-30 min, and then the porous SiC

[0022] Preferably, the porous SiC f / SiC composite material is prepared according to the following steps:

[0023] A boron nitride (BN) interfacial phase is prepared on the surface of a two-dimensional SiC fiber braid to obtain a SiC fiber preform; wherein the thickness of the interfacial phase is 100-400 nm.

[0024] A certain volume fraction of SiC matrix is deposited in the SiC fiber preform by using a CVI process to obtain the porous SiC f / SiC composite material, which has a porosity of 28-36% and a density of 1.7-2.1 g / cm 3 .

[0025] Preferably, when depositing a certain volume fraction of SiC matrix in SiC fiber preform using the CVI process, trichloromethylsilane is used as the precursor, hydrogen as the carrier gas, and argon as the dilution gas, with a flow ratio of 1:5 to 50:2 to 20, a total gas pressure of 0.5 to 5 kPa, a deposition temperature of 873 to 1773 K, and a deposition time of approximately 600 hours.

[0026] The second objective of this invention is to provide a method for the low-temperature preparation of water-resistant, oxygen-modified SiC using a boron-containing mesophase-assisted process. f / SiC composite material.

[0027] Preferably, the modified composite material has a porosity of less than 13% and a density greater than 2.5 g / cm³. 3 .

[0028] The third objective of this invention is to provide a method for the low-temperature preparation of water-resistant, oxygen-modified SiC using a boron-containing mesophase-assisted process. f Application of SiC composite materials in thermal structural materials for aero-engines.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] This invention provides a method for the low-temperature preparation of water-resistant, oxygen-modified SiC using a boron-containing mesophase-assisted process. f / SiC composite materials, their preparation methods, and applications. The method first involves preparing a boron-containing furfural-furfuryl alcohol transparent resin (R... P Introduced into porous SiC by vacuum impregnation. f In the / SiC composite material, then R P Resin and porous SiC f The SiC composite material was transferred to a thermostatic curing autoclave for impregnation and curing, then placed in a tube furnace for pyrolysis, and finally the modified SiC was cured at low temperature using the RMI method. f Densification of SiC composites. Warm-press curing promotes the polycondensation of furfural and furfuryl alcohol, significantly shortening the self-assembly time of small molecules and reducing the preparation time of SiC. f The addition of copolymers improves the pore structure and toughness of porous resins, allowing them to maintain their original pore structure even after direct air drying and pyrolysis. During RMI (Regenerative Molecular Mixture), interconnected and uniformly porous boron-containing carbon reacts with Y-Si melt to form a dense, uniformly distributed SiC, Si-YBC mesophase, and Y3Si5 (melting point 1612℃) multiphase matrix. This method rapidly prepares modified SiC. f / SiC composite materials possess high density and excellent mechanical properties, effectively solving the current challenges in preparing modified SiC using the RMI process. fThe SiC composite material has problems of high temperature, high content of residual alloy with low melting point, uneven matrix component and structure.

[0031] The present application can control the content and morphology of the resin by adjusting the volume fraction of furfural and formaldehyde, and further control the content and morphology of the pyrolysis carbon; the pore diameter and volume of the porous resin can be controlled by adjusting the temperature and time of warm-pressing curing, and further control the pore size and porosity of the Si-Y alloy pore channel; the degree of branched chain bonding of the resin can be controlled by adjusting the content of ammonium borate, and further control the distribution and content of boron in the porous carbon; the liquid silicon penetration depth and the degree of carbon-silicon reaction can be controlled by adjusting the Y-Si alloy penetration temperature and time, and further improve the density and mechanical properties of the composite material.

[0032] The boron-containing transparent resin prepared by using ethanol and water as solvents can be efficiently infiltrated into the porous SiC f The content of carbon and boron in the SiC composite material can be effectively controlled by circulating impregnation, which lays a foundation for preparing the modified SiC f The content of carbon and boron in the SiC composite material can be effectively controlled by circulating impregnation, which lays a foundation for preparing the modified SiC f The content of carbon and boron in the SiC composite material can be effectively controlled by circulating impregnation, which lays a foundation for preparing the modified SiC Figure 3 The content of carbon and boron in the SiC composite material can be effectively controlled by circulating impregnation, which lays a foundation for preparing the modified SiC f The content of carbon and boron in the SiC composite material can be effectively controlled by circulating impregnation, which lays a foundation for preparing the modified SiC

[0033] In the preparation process of the boron-containing furfuryl alcohol-furfural resin, the triblock copolymer (P123) is added to improve the pore structure of the porous resin and improve the toughness of the porous resin, which can avoid the adverse effects of incomplete polymerization of small molecules caused by the addition of ammonium borate, and can also avoid the collapse of the pore channel caused by capillary force during drying or pyrolysis, simplifying the drying process and shortening the drying time.

[0034] The warm-pressing curing method provides heating and pressurizing conditions, which can promote the condensation of furfuryl alcohol and furfural depending on the triblock copolymer to quickly build the main chain of the resin, and promote the combination of formaldehyde and ammonium borate, and then connect to the process of the resin branched chain. The warm-pressing curing method greatly reduces the synthesis time of the boron-containing porous resin, and shortens the preparation period of the modified SiC f The content of carbon and boron in the SiC composite material can be effectively controlled by circulating impregnation, which lays a foundation for preparing the modified SiC

[0035] The present application utilizes the intermediate phase to prepare modified SiC f / SiC composite, on the one hand, the preparation temperature is reduced, and the fiber damage is reduced; on the other hand, the early appearance of low-temperature Y-Si phase is avoided, and the ultimate use temperature of the composite material is improved. In addition, by adjusting the carbon content, the modified SiC f / SiC composite has a high SiC phase content, and by adjusting the carbon structure, the SiC and residual alloy phase are dispersedly embedded, and the mechanical properties of the composite material are improved.

[0036] The resin curing and cracking can effectively make the Y element uniformly distributed in the porous SiC f / SiC composite, on the one hand, the subsequent alloy can uniformly penetrate into the entire composite material, and on the other hand, the matrix phase structure can be controlled. By using alloy infiltration, a high-density modified matrix can be prepared to improve the oxidation resistance of the composite material. The process of resin curing and cracking combined with alloy infiltration can obtain a composite material with controllable matrix composition and structure under the premise of ensuring high density. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The present application relates to the preparation process flow chart.

[0038] Figure 2 The water and oxygen resistant matrix modified SiC f / SiC composite material prepared in examples 1-3.

[0039] Figure 3 The water and oxygen resistant matrix modified SiC f / SiC composite material prepared in example 3.

[0040] Figure 4 The water and oxygen resistant matrix modified SiC f / SiC composite material prepared in examples 1-3. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solutions of the present application and to implement them, the present application will be further described below in conjunction with specific examples and drawings, but the examples are not limiting to the present application.

[0042] The present application can effectively make the Y element uniformly distributed in the porous SiC fThe problem can be effectively solved by introducing a porous carbon material containing boron elements into the / SiC composite material. Meanwhile, considering the wettability of Y-Si alloy and boron-doped carbon, the content of boron elements should be strictly controlled so that the boron elements can play a role of connecting Y-Si and C as an intermediate phase without hindering the wettability, avoiding the Y-Si phase from being precipitated in advance, and reducing the infiltration temperature.

[0043] The application provides a method for preparing a matrix-modified SiC f composite material at a low temperature with the aid of an intermediate phase. f The application provides a process method for preparing a matrix-modified SiC

[0044] The application provides a method for preparing a matrix-modified SiC f composite material at a low temperature with the aid of an intermediate phase.

[0045] The application provides a method for preparing a matrix-modified SiC f composite material at a low temperature with the aid of an intermediate phase.

[0046] Furfuryl alcohol and a triblock copolymer are dispersed in an ethanol aqueous solution to obtain a mixed solution I.

[0047] Ammonium borate hexahydrate is dispersed in a 37wt.% formaldehyde aqueous solution to obtain a mixed solution II.

[0048] The mixed solution I and the mixed solution II are mixed, and then 25wt.% ammonia water is added and uniformly mixed to obtain a boron-containing resin precursor solution.

[0049] The porous SiC f composite material is immersed in the boron-containing resin precursor solution, and then subjected to a curing treatment to obtain a cured composite.

[0050] The cured composite is kept at 900-1100 DEG C. for 2-4 hours under the protection of an inert gas to obtain a pyrolyzed composite.

[0051] The pyrolyzed composite is wrapped with Y-Si powder, and the outermost layer is wrapped with graphite paper, and then subjected to a reaction melt infiltration at 1260-1300 DEG C. under vacuum for 10-30 min. to obtain a matrix-modified SiC f composite material.

[0052] The mass ratio of the furfuryl alcohol to the triblock copolymer is 3-12:1, and the mass ratio of the ammonium borate hexahydrate to the 37wt.% formaldehyde aqueous solution is 1:1.5-5.

[0053] The aqueous ethanol solution is prepared by mixing water solvent and anhydrous ethanol at a volume ratio of 1:0.75-5.

[0054] The solidification treatment comprises: immersing the porous SiC f / SiC composite into a boron-containing resin precursor solution, heating to 80-150°C at a heating rate of 3-5°C / min in a curing oven, pressurizing to 1.5-3 MPa, and then drying in an air environment at 80-120°C for 20-40 min.

[0055] Specifically, the porous SiC f / SiC composite is immersed into the boron-containing resin precursor solution by the following steps: f / SiC composite and the boron-containing resin precursor solution into a container, vacuumizing the container to a pressure of <0.09 MPa, and then immersing the porous SiC f / SiC composite into the boron-containing resin precursor solution for 20-30 min.

[0056] The porous SiC f / SiC composite is prepared by the following steps:

[0057] A boron nitride (BN) interfacial phase is prepared on the surface of a two-dimensional SiC fiber braid to obtain a SiC fiber preform; the thickness of the interfacial phase is 100-400 nm.

[0058] A certain volume fraction of SiC matrix is deposited in the SiC fiber preform by a CVI process to obtain the porous SiC f / SiC composite, which has a porosity of 28-36% and a density of 1.7-2.1 g / cm 3 .

[0059] Specifically, when a certain volume fraction of SiC matrix is deposited in the SiC fiber preform by the CVI process, trichloromethylsilane is used as a precursor, hydrogen is used as a carrier gas, and argon is used as a dilution gas; the flow rate ratio of the three is 1:5-50:2-20, the total gas pressure is 0.5-5 kPa, the deposition temperature is 873-1773 K, and the deposition time is about 600 hours.

[0060] In one embodiment, a method for preparing a water-oxygen resistant matrix modified SiC f / SiC composite at a low temperature with the assistance of a boron-containing intermediate phase is provided, as shown in Figure 1 The specific steps are as follows:

[0061] Step 1. Preparation of a porous SiC f / SiC composite:

[0062] Step 1.1 A two-dimensional SiC fiber braid (2D SiC fiber preform) is used to prepare a boron nitride (BN) interface phase on its surface for the purpose of protecting the fibers and transferring stress. Boron trichloride (BCl3) and ammonia (NH3) are introduced in a ratio of 0.45:0.55, and the ratio of dilution gas hydrogen (H2) to reaction gas (dilution ratio) is d(H2)=10~20. Argon (Ar) is introduced to maintain the pressure in the furnace at 1~2kPa, the deposition temperature is 650~800℃, and the deposition time is 10~20h. A BN interface layer with a thickness of 100~400nm is obtained.

[0063] Step 1.2 A certain volume fraction of SiC matrix is prepared in the SiC fiber preform obtained in step 1.1 using the CVI process; trichloromethylsilane (MTS) is used as the precursor, hydrogen is used as the carrier gas, and argon is used as the dilution gas. The flow ratio of the three is 1:5~50:2~20, the total gas pressure is 0.5~5kPa, the deposition temperature is 873~1773K, and the deposition time is about 600 hours. A porous SiC 3 / SiC composite material with a porosity of 28~36% and a density of 1.7~2.1g / cm f is obtained, which is used for subsequent slurry impregnation; a porous SiC f / SiC composite material is obtained.

[0064] Step 2. Preparation of boron-containing resin:

[0065] Step 2.1 Furfuryl alcohol 10~20g and triblock copolymer 5~10g are added to container 1 containing an aqueous ethanol solution, and magnetic stirring is performed for 5~10min. Then, 20~36g of furfuryl alcohol is added, and magnetic stirring is performed for 15min.

[0066] Step 2.2 8~13g of 37wt.% formaldehyde aqueous solution and 2.6~5.2g of ammonium borate hexahydrate are added to container 2, respectively, and magnetic stirring is performed for 20min.

[0067] Step 2.3 Then, the solution in container 2 is transferred to container 1, and magnetic stirring is performed for 5min. Then, 1~1.5g of 25wt.% ammonia water is added, and magnetic stirring is performed for 10~20min to obtain a transparent solution, i.e., a boron-containing resin precursor R P ; that is, a boron-containing resin precursor solution;

[0068] The aqueous ethanol solution is an aqueous ethanol solution obtained by mixing 15~40ml of water with 30~80ml of anhydrous ethanol;

[0069] Step 3. Resin sol impregnation:

[0070] A porous SiC f / SiC composite material and the boron-containing resin precursor R obtained in step 2 P Put into a glass drying dish, vacuumize to a pressure lower than 0.09 MPa in the glass dish, and keep for 20-30 min, then put the porous SiC f / SiC composite material into the solution and keep for 20-30 min to obtain SiC impregnated with the resin precursor f / SiC-R P .

[0071] Step 4. Crosslinking and curing of the boron-containing resin:

[0072] Put the SiC obtained in step 3 f / SiC-R P into the solution, and keep for 20-30 min to obtain SiC impregnated with the resin precursor f / SiC-R c , which is the cured composite.

[0073] Step 5. Pyrolysis of the boron-containing resin:

[0074] Put the SiC obtained in step 4 f / SiC-R c (cured composite) into a horizontal tube furnace, heat to 900-1100℃ at a rate of 5-10℃ / min, keep for 2-4 hours, and pass 100-150 sccm of argon as protective gas throughout the process, so that the resin gel in the composite material is pyrolyzed into boron-containing carbon, to obtain SiC f / SiC-C(B), which is the pyrolyzed composite.

[0075] Step 6. Alloy infiltration:

[0076] Put the SiC obtained in step 5 f / SiC-C(B) (pyrolyzed composite) into a silicon infiltration furnace, and react with the molten silicon at 1260-1300℃ in a vacuum environment for 10-30 min to complete densification, so as to quickly prepare a modified SiC with controllable components and structure f / SiC composite material, which is the water-oxygen-resistant matrix modified SiC f / SiC composite material

[0077] The second aspect of the present application provides a boron-containing mesophase assisted low-temperature preparation of a water-oxygen-resistant matrix modified SiC f / SiC composite material. The porosity of the modified composite material is less than 12%, and the density is greater than 2.5 g / cm3 .

[0078] The third aspect of the present application provides a boron-containing mesophase-assisted low-temperature preparation of a water-oxygen-resistant matrix modified SiC f / SiC composite material in the application of aero-engine thermal structural materials.

[0079] 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.

[0080] Example 1

[0081] A boron-containing mesophase-assisted low-temperature preparation of a water-oxygen-resistant matrix modified SiC f / SiC composite material, comprising the following steps:

[0082] Step 1. Preparation of porous SiC f / SiC composite material:

[0083] Step 1.1 A two-dimensional SiC fiber braid is used to prepare a boron nitride (BN) interface phase on its surface, and a mixture of boron trichloride (BCl3) and ammonia gas (NH3) with a ratio of 0.45:0.55 is introduced, and the ratio of dilution gas hydrogen (H2) to reaction gas (dilution ratio) is d(H2)=10. Argon (Ar) is introduced to maintain the pressure in the furnace at 1kPa, the deposition temperature is 650℃, the deposition time is 10h, and a BN interface layer with a thickness of 100nm is obtained.

[0084] Step 1.2 A certain volume fraction of SiC matrix is prepared in the SiC fiber preform obtained in step 1.1 using the CVI process. Trichloromethylsilane (MTS) is used as the precursor, hydrogen gas is used as the carrier gas, and argon gas is used as the dilution gas, with a flow ratio of 1:5:2, a total gas pressure of 0.5kPa, a deposition temperature of 873K, and a deposition time of about 600 hours. Thus, a porous SiC 3 / SiC composite material with a porosity of 28% and a density of 2.1g / cm f is obtained for subsequent slurry impregnation.

[0085] Step 2. Preparation of boron-containing resin:

[0086] Step 2.1 Add 10g of furfuryl alcohol and 5g of triblock copolymer to container 1 containing an aqueous ethanol solution, and magnetically stir for 5min, then add 20g of furfuryl alcohol and magnetically stir for 15min.

[0087] Step 2.2 Add 8g of 37wt.% formaldehyde solution and 2.6g of ammonium borate hexahydrate to container 2, respectively, and magnetically stir for 20min.

[0088] Step 2.3: The solution in container 2 is then transferred to container 1 and magnetically stirred for 5 minutes. Then, 1 g of 25 wt.% ammonia solution is added, and the mixture is magnetically stirred for 10 minutes to obtain a transparent solution, which is the boron-containing resin precursor R. P .

[0089] The ethanol-water solution is an ethanol-water solution obtained by mixing 15 ml of water with 30 ml of anhydrous ethanol.

[0090] Step 3. Resin sol impregnation:

[0091] Porous SiC with a porosity of 28% f / SiC composite material and boron-containing resin precursor R obtained in step 2 P Place the porous SiC material in a glass desiccator, evacuate the glass until the pressure inside the desiccator is below 0.09 MPa, maintain this pressure for 20 minutes, and then place the desiccator inside the glass. f / SiC composite material is immersed in solution for 20 minutes to obtain SiC impregnated with resin precursor. f / SiC-R P .

[0092] Step 4. Crosslinking and curing of boron-containing resin:

[0093] The SiC obtained in step 3 f / SiC-R P The remaining transparent solution was poured into a thermostatic curing autoclave, heated to 80°C at a heating rate of 3°C / min, pressurized to 2 MPa, and held at that temperature for 2 hours. Afterward, it was removed and dried in air at 80°C for 30 minutes to obtain SiC. f / SiC-R c .

[0094] Step 5. Pyrolysis of boron-containing resin:

[0095] The SiC obtained in step 4 f / SiC-R c The material was placed in a horizontal tube furnace and heated to 900℃ at a rate of 5℃ / min, held at that temperature for 2 hours, with argon gas at 100 sccm purging throughout as a protective gas. This caused the resin gel in the composite material to decompose into boron-containing carbon, yielding SiC. f / SiC-C(B).

[0096] Step 6. Alloy infiltration:

[0097] The SiC obtained in step 5 fThe Y-Si powder is wrapped with SiC-C(B), and the outermost layer is wrapped with graphite paper. Then, the composite material wrapped with Y-Si powder is placed in a silicon infiltration furnace, and reaction melt infiltration is carried out at 1260°C in a vacuum environment for 10 min to complete densification, so that the modified SiC with controllable components and structure is quickly prepared f The SiC composite material (X1) is prepared.

[0098] The final SiC f The density of the SiC 3 composite material is 2.62 g / cm f , and the open porosity is 10.48%. Test shows that the room temperature bending strength of the SiC f composite material is 340 MPa.

[0099] Example 2

[0100] A boron-containing mesophase assisted low-temperature preparation of a water-oxygen resistant matrix modified SiC f The preparation method of the SiC composite material comprises the following steps:

[0101] Step 1. Preparation of porous SiC f composite material:

[0102] Step 1.1 A two-dimensional SiC fiber braid is used to prepare a boron nitride (BN) interface phase on the surface thereof, and a mixture of boron trichloride (BCl3) and ammonia gas (NH3) in a ratio of 0.45:0.55 is introduced, and the ratio (dilution ratio) of dilution gas hydrogen (H2) to reaction gas is d(H2)=15. Argon (Ar) is introduced to maintain the pressure in the furnace at 1.5 kPa, the deposition temperature is 740°C, and the deposition time is 15 h, so that a BN interface layer with a thickness of 200 nm is obtained.

[0103] Step 1.2 A certain volume fraction of SiC matrix is prepared in the SiC fiber preform obtained in step 1.1 by using the CVI process. Trichloromethylsilane (MTS) is used as a precursor, hydrogen is used as a carrier gas, and argon is used as a dilution gas. The flow rate ratio of the three is 1:20:10, the total gas pressure is 3 kPa, the deposition temperature is 1073 K, and the deposition time is about 600 hours. Thus, a porous SiC 3 composite material with a porosity of 32% and a density of 1.9 g / cm f is obtained, which is used for subsequent slurry impregnation.

[0104] Step 2. Preparation of boron-containing resin:

[0105] Step 2.1 Furfuryl alcohol 15 g and triblock copolymer 8 g are added to a container 1 containing an aqueous ethanol solution, and magnetic stirring is carried out for 8 min. Then, 28 g of furfuryl alcohol is added, and magnetic stirring is carried out for 15 min.

[0106] Step 2.2 10 g of 37 wt.% aqueous formaldehyde solution and 3.8 g of ammonium borate hexahydrate were added into container 2, respectively, and magnetically stirred for 20 min.

[0107] Step 2.3 The solution in container 2 was then transferred into container 1, magnetically stirred for 5 min, and 1.3 g of 25 wt.% ammonia water was added, magnetically stirred for 15 min, to obtain a transparent solution, i.e., boron-containing resin precursor R P .

[0108] The aqueous ethanol solution was obtained by mixing 25 ml of water and 50 ml of anhydrous ethanol.

[0109] Step 3. Resin sol impregnation:

[0110] The porous SiC f / SiC composite material with a porosity of 32% and the boron-containing resin precursor R P obtained in step 2 were placed in a glass drying dish, vacuumized to a pressure lower than 0.09 MPa in the glass dish, and maintained for 25 min, and then the porous SiC f / SiC composite material was immersed in the solution for 25 min to obtain SiC f / SiC-R P .

[0111] Step 4. Boron-containing resin crosslinking and curing:

[0112] The SiC f / SiC-R P obtained in step 3 was poured into a warm-pressing curing kettle together with the remaining transparent solution, heated to 120°C at a heating rate of 4°C / min, pressurized to 2 MPa, and maintained for 6 hours, and then taken out and dried at 100°C in an air environment for 30 min to obtain SiC f / SiC-R c .

[0113] Step 5. Boron-containing resin pyrolysis:

[0114] The SiC f / SiC-R c obtained in step 4 was placed in a horizontal tube furnace, heated to 1000°C at a heating rate of 7°C / min, and maintained for 3 hours, and 120 sccm of argon gas was introduced as a protective gas throughout the process to pyrolyze the resin gel in the composite material into boron-containing carbon, to obtain SiC f / SiC-C(B).

[0115] Step 6. Alloy infiltration:

[0116] The SiC fThe / SiC-C(B) is wrapped with Y-Si powder, and the outermost layer is wrapped with graphite paper. Then, the composite material wrapped with Y-Si powder is placed in a silicon infiltration furnace, and reaction melt infiltration is carried out at 1280 ℃ in a vacuum environment for 20 min to complete densification, so that the modified SiC with controllable composition and structure is quickly prepared f The / SiC composite material (X2).

[0117] The density of the final SiC f / SiC composite material is 3.00 g / cm 3 , and the open porosity is 5.31%. Test shows that the room temperature bending strength of the SiC f / SiC composite material is 210 MPa.

[0118] Example 3

[0119] A boron-containing mesophase assisted low-temperature preparation of water-oxygen resistant matrix modified SiC f The preparation method of the / SiC composite material comprises the following steps:

[0120] Step 1. Preparation of porous SiC f / SiC composite material:

[0121] Step 1.1 A two-dimensional SiC fiber braid is used to prepare a boron nitride (BN) interface phase on its surface. Boron trichloride (BCl3) and ammonia (NH3) are introduced in a ratio of 0.45:0.55, and the ratio of dilution gas hydrogen (H2) to reaction gas (dilution ratio) is d(H2)=20. Argon (Ar) is introduced to maintain the pressure in the furnace at 2 kPa, the deposition temperature is 800 ℃, and the deposition time is 20 h to obtain a BN interface layer with a thickness of 400 nm.

[0122] Step 1.2 A certain volume fraction of SiC matrix is prepared in the SiC fiber preform obtained in step 1.1 by CVI process. Trichloromethylsilane (MTS) is used as a precursor, hydrogen is used as a carrier gas, and argon is used as a dilution gas. The flow ratio of the three is 1:50:20, the total gas pressure is 5 kPa, the deposition temperature is 1273 K, and the deposition time is about 600 hours. Thus, a porous SiC 3 / SiC composite material with a porosity of 36% and a density of 1.7 g / cm f is obtained, which is used for subsequent slurry impregnation.

[0123] Step 2. Preparation of boron-containing resin:

[0124] Step 2.1 Furfuryl alcohol 20 g and triblock copolymer 10 g are added to a container 1 containing an aqueous ethanol solution, and magnetically stirred for 10 min. Then, 36 g of furfuryl alcohol is added, and magnetically stirred for 15 min.

[0125] Step 2.2 Add 13 g of 37 wt.% aqueous formaldehyde solution and 5.2 g of ammonium borate hexahydrate into container 2, respectively, and magnetically stir for 20 min.

[0126] Step 2.3 Then transfer the solution in container 2 into container 1, magnetically stir for 5 min, and then add 1.5 g of 25 wt.% ammonia water, magnetically stir for 20 min, to obtain a transparent solution, i.e., boron-containing resin precursor R P .

[0127] The aqueous ethanol solution is an aqueous ethanol solution obtained by mixing 40 ml of water and 80 ml of anhydrous ethanol.

[0128] Step 3. Resin sol impregnation:

[0129] Put the porous SiC f / SiC composite material with a porosity of 36% and the boron-containing resin precursor R P obtained in step 2 into a glass drying dish, and vacuumize the glass dish to a pressure lower than 0.09 MPa, and keep for 30 min. Then immerse the porous SiC f / SiC composite material in the solution for 30 min to obtain SiC f / SiC-R P .

[0130] Step 4. Boron-containing resin crosslinking and curing:

[0131] Pour the SiC f / SiC-R P obtained in step 3 and the remaining transparent solution into a warm-pressing curing kettle, heat to 150 °C at a heating rate of 5 °C / min, pressurize to 2 MPa, and keep for 12 hours. Then take out and dry at 120 °C in air for 30 min to obtain SiC f / SiC-R c .

[0132] Step 5. Boron-containing resin pyrolysis:

[0133] Put the SiC f / SiC-R c obtained in step 4 into a horizontal tube furnace, heat to 1100 °C at a heating rate of 10 °C / min, and keep for 4 hours. Throughout the process, 150 sccm of argon gas is introduced as a protective gas. The resin gel in the composite material is pyrolyzed to form boron-containing carbon to obtain SiC f / SiC-C(B).

[0134] Step 6. Alloy infiltration:

[0135] Put the SiC fThe SiC-C(B) is wrapped with Y-Si powder, and the outermost layer is wrapped with graphite paper, and then the composite material wrapped with Y-Si powder is placed in a silicon infiltration furnace, and reaction melt infiltration is carried out at 1300 DEG C in a vacuum environment for 30 min, and densification is completed, so that the modified SiC with controllable composition and structure is rapidly prepared f / SiC composite material (X3).

[0136] The density of the final SiC f / SiC composite material is 2.85 g / cm 3 , and the open porosity is 5.21%. Test shows that the room temperature bending strength of the SiC f / SiC composite material is 570 MPa.

[0137] In order to illustrate the related performance of the water-oxygen-resistant matrix modified SiC f / SiC composite material provided by the application, the application is described in combination with the drawings.

[0138] Figure 2 The density and porosity of the water-oxygen-resistant matrix modified SiC f / SiC composite material prepared in examples 1-3.

[0139] As can be seen from the table, Figure 2 the X2 and X3 composite materials prepared in the examples have high density and low porosity, which meet the requirements of high density and oxidation resistance.

[0140] Figure 3 The cross-sectional morphology of the water-oxygen-resistant matrix modified SiC f / SiC composite material prepared in example 3.

[0141] As can be seen from the table, Figure 3 the modified SiC f / SiC composite material prepared in example 3 has almost no closed pore defects. The matrix mainly consists of SiC, Y3Si5 and intermediate phase Si-Y-B-C, and each phase is uniformly dispersed.

[0142] Figure 4 The bending strength of the water-oxygen-resistant matrix modified SiC f / SiC composite material prepared in examples 1-3.

[0143] As can be seen from the table, Figure 4 the bending strength of the composite material prepared in X3 is higher than that of X1 and X2, which indicates that the dispersed matrix can effectively improve the strength of the composite material.

[0144] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A method for low-temperature preparation of water-resistant modified SiC with boron-containing mesophase assistance. f The method for using SiC composite materials is characterized by... Includes the following steps: Preparation of porous SiC f / SiC composite materials; Furfuryl alcohol and the triblock copolymer were dispersed in an aqueous ethanol solution to obtain mixed solution I; Ammonium borate hexahydrate was dispersed in a 37 wt.% formaldehyde aqueous solution to obtain mixed solution II; After mixing mixed solution I and mixed solution II, 25 wt.% ammonia water is added and mixed evenly to obtain a boron-containing resin precursor solution; porous SiC f The SiC composite material is immersed in a boron-containing resin precursor solution and then cured to obtain a cured composite. Under the protection of inert gas, the solidified composite is kept at 900~1100℃ for 2~4 hours to obtain the pyrolysis composite; The pyrolysis composite was coated with Y-Si powder and then wrapped with graphite paper as the outermost layer. The mixture was then subjected to a reaction melt infiltration process under vacuum at 1260–1300 °C for 10–30 min to obtain water-resistant, oxygen-modified SiC. f / SiC composite materials; The triblock copolymer is P123; porous SiC f When SiC composite materials are immersed in a boron-containing resin precursor solution, the process includes: immersing porous SiC... f The SiC composite material and boron-containing resin precursor solution were placed in a container, and a vacuum was drawn until the pressure inside the container was <0.09 MPa. After maintaining this vacuum for 20-30 minutes, the porous SiC was then added. f / SiC composite material is immersed in boron-containing resin precursor solution for 20-30 minutes; The curing process includes: porous SiC f After the SiC composite material is immersed in a boron-containing resin precursor solution, it is heated to 80-150°C in a curing autoclave at a heating rate of 3-5°C / min and pressurized to 1.5-3MPa. After holding at this temperature for 2-12 hours, it is dried in an air environment at 80-120°C for 20-40 minutes.

2. The method for preparing water-resistant modified SiC using boron-containing mesophase-assisted low-temperature preparation according to claim 1 f The method for using SiC composite materials is characterized by... The mass ratio of furfuryl alcohol to the triblock copolymer is 3~12:1; the mass ratio of ammonium borate hexahydrate to 37wt.% formaldehyde aqueous solution is 1:1.5~5.

3. The method for preparing water-resistant modified SiC using a boron-containing mesophase-assisted low-temperature process according to claim 1. f The method for using SiC composite materials is characterized by... The ethanol-water solution is prepared by mixing an aqueous solvent and anhydrous ethanol in a volume ratio of 1:0.75~5.

4. The method for preparing water-resistant modified SiC using boron-containing mesophase-assisted low-temperature preparation according to claim 1 f The method for using SiC composite materials is characterized by... The porous SiC f The SiC composite material is prepared according to the following steps: A boron nitride (BN) interface phase was prepared on the surface of a two-dimensional SiC fiber braid to obtain a SiC fiber preform; wherein the thickness of the interface phase was 100~400 nm. A certain volume fraction of SiC matrix is ​​deposited in a SiC fiber preform using the CVI process, thus creating porous SiC. f The SiC composite material has a porosity of 28-36% and a density of 1.7-2.1 g / cm³. 3 .

5. The method for preparing water-resistant modified SiC using a boron-containing mesophase-assisted low-temperature process according to claim 4. f The method for using SiC composite materials is characterized by... When depositing a certain volume fraction of SiC matrix in SiC fiber preform using the CVI process, trichloromethylsilane is used as the precursor, hydrogen as the carrier gas, and argon as the dilution gas. The flow ratio of the three is 1:5 to 50:2 to 20, the total gas pressure is 0.5 to 5 kPa, the deposition temperature is 873 to 1773 K, and the deposition time is 600 hours.

6. A method for preparing hydrophobic modified SiC using a boron-containing mesophase assisted low-temperature process according to any one of claims 1 to 5. f / SiC composite material.

7. The method for preparing water-resistant modified SiC using a boron-containing mesophase-assisted low-temperature process according to claim 6. f / SiC composite material, characterized in that The modified SiC f The porosity of the SiC composite material is less than 12%, and the density is greater than 2.5 g / cm³. 3 .

8. A method for preparing water-resistant, oxygen-modified SiC using a boron-containing mesophase-assisted low-temperature process as described in claim 6. f Application of SiC composite materials in thermal structural materials for aero-engines.

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