A method for preparing a low-residue silicon-SiC composite material and a method for preparing liquid phenolic resin.

Abstract

This invention provides a method for preparing a low-residual-silicon SiC composite material and a method for preparing liquid phenolic resin, relating to the field of SiC composite material preparation technology. The method includes: preparing a SiC fiber preform using SiC fiber bundles and shaping it in a graphite mold to obtain a fiber preform with a graphite mold; preparing a SiC interface layer to obtain a porous SiC / BN / Si-C-N composite material with a graphite mold; depositing a SiC matrix to obtain a porous SiC / BN / Si-C-N / SiC composite material; and impregnating, pyrolyzing, and siliconizing the porous SiC / BN / Si-C-N / SiC composite material using liquid phenolic resin to obtain the SiC / BN / Si-C-N / SiC composite material. The SiC composite material prepared by this method has the characteristics of low porosity, high strength, and low preparation cost.

Description

Technical Field

[0001] This invention relates to the field of SiC composite material preparation technology, specifically to a method for preparing a low-residual-silicon SiC composite material and a method for preparing liquid phenolic resin. Background Technology

[0002] SiC / SiC composites are high-temperature resistant, low-density ceramic matrix thermal structural composites that have been applied or tested in civilian and military equipment fields such as commercial engines, high thrust-to-weight ratio military aero engines, satellite attitude control engines, hypersonic ramjet engines, and space repatriation thermal protection systems. Short-cycle, low-cost manufacturing processes are one of the key issues that need to be addressed for the widespread engineering application of SiC / SiC composites. Currently, the manufacturing cost of ceramic matrix composites is high not only due to the high price of raw material SiC fiber, but also because the densification process has a long cycle, resulting in high electricity, water, gas, labor, and equipment maintenance costs, which limits the widespread application of SiC / SiC composites. Extensive research has been conducted both domestically and internationally on low-cost, short-cycle SiC / SiC composite manufacturing technologies. For example, GE in the United States developed a prepreg combined with melt infiltration (RMI) process for manufacturing SiC / SiC composites. This process fully utilizes the advantages of RMI, offering short cycle times and low costs, making it suitable for manufacturing SiC / SiC components such as turbine outer rings, guide vanes, and combustion chamber flame tubes.

[0003] Residual silicon is inevitably present in SiC / SiC prepared using the RMI process. When residual silicon aggregates in large quantities within SiC / SiC, its mechanical properties deteriorate sharply. Introducing dispersed SiC particles to separate the residual silicon from the matrix can effectively mitigate this adverse effect. Two main methods exist: ① directly introducing SiC particles using slurry impregnation or slurry-casting; ② introducing carbon to generate dispersed SiC particles / grains in situ using a carbon-silicon reaction. Researchers in the United States have used slurry-casting combined with melt infiltration (MI) to prepare high-density, high-strength SiC / SiC, which has been practically applied to components such as F414 low-pressure turbine blades. However, it is worth noting that the slurry process is limited by the pore structure and shape of the semi-dense composite material, making it difficult to prepare large-size and structurally complex components. Furthermore, the absence of a C-Si reaction during infiltration results in a high residual silicon content within the SiC / SiC, limiting the increase in its operating temperature. Furthermore, due to the significant difference in modulus between SiC fibers, BN interfaces, and CVI SiC matrix, the stress distribution is uneven when the material is subjected to force, which easily leads to stress concentration at the interface, causing cracks to be triggered and propagated more rapidly, thus reducing the mechanical properties of the material. Summary of the Invention

[0004] In view of this, the embodiments of this specification provide a method for preparing a low-residual silicon SiC composite material and a method for preparing liquid phenolic resin, so as to achieve the purpose of rapidly and cost-effectively manufacturing SiC / SiC composite materials.

[0005] The embodiments in this specification provide the following technical solutions:

[0006] A method for preparing a low-residual silicon SiC composite material, comprising:

[0007] SiC fiber preforms were prepared using SiC fiber bundles, and then the SiC fiber preforms were placed in a graphite mold for shaping to obtain a fiber preform with a graphite mold.

[0008] A continuous and uniform BN interface layer is prepared on the surface of SiC fibers in a fiber preform to obtain a fiber preform containing a BN interface layer. Based on the fiber preform containing a BN interface layer, a Si-CN interface layer is prepared to obtain a porous SiC / BN / Si-CN composite material with a graphite mold.

[0009] A SiC matrix was prepared in a porous SiC / BN / Si-CN composite material using the CVI process, resulting in a porous SiC / BN / Si-CN / SiC composite material.

[0010] Porous SiC / BN / Si-CN / SiC composite materials were impregnated and pyrolyzed using liquid phenolic resin to obtain porous SiC / BN / Si-CN / SiC / C composite materials.

[0011] The porous SiC / BN / Si-CN / SiC / C composite material was subjected to silicon infiltration treatment to obtain the SiC / BN / Si-CN / SiC composite material.

[0012] Furthermore, based on the fiber preform containing the BN interface layer, a Si-CN interface layer is prepared to obtain a porous SiC / BN / Si-CN composite material with a graphite mold, including:

[0013] The fiber preform containing the BN interface layer is placed into a CVI Si-CN deposition furnace;

[0014] A porous SiC / BN / Si-CN composite material with a graphite mold is obtained by preparing a Si-CN interface layer using the CVI process. The thickness of the BN interface layer is 200 nm to 600 nm, and the thickness of the Si-CN interface layer is 300 nm to 500 nm. The Si-CN interface layer is a ceramic interface layer containing Si, C, and N elements, including but not limited to one or more combinations of SiCN ceramic, Si3N4 ceramic, and SiBCN ceramic.

[0015] Furthermore, the graphite mold includes a female mold and a male mold. The surfaces of both the female mold and the male mold are provided with a first through hole with a diameter of Ф4mm~Ф6mm. The hole spacing of the first through hole is 8mm~12mm. The thickness of both the female mold and the male mold is 10~15mm. The four corners of the female mold and the male mold are respectively provided with a second through hole with a diameter of Ф10mm~Ф12mm. The edge distance of the second through hole is 20mm~24mm.

[0016] Furthermore, a SiC matrix is ​​prepared in the porous SiC / BN / Si-CN composite material using the CVI process to obtain a porous SiC / BN / Si-CN / SiC composite material, comprising:

[0017] The SiC matrix was prepared using the CVI process, and the porous SiC / BN / Si-CN composite material with a graphite mold was placed in a SiC vapor deposition furnace to deposit the SiC matrix.

[0018] After removing the graphite mold, a porous SiC / BN / Si-CN / SiC composite material is obtained.

[0019] Furthermore, using liquid phenolic resin, the porous SiC / BN / Si-CN / SiC composite material is impregnated and pyrolyzed to obtain a porous SiC / BN / Si-CN / SiC / C composite material, comprising:

[0020] The porous SiC / BN / Si-CN / SiC composite material was placed in a vacuum impregnation vessel and a vacuum was drawn.

[0021] When the vacuum degree of the vacuum impregnation vessel is less than 100 Pa, under the action of pressure difference, liquid phenolic resin is introduced into the vacuum impregnation vessel so that the liquid phenolic resin completely impregnates the porous SiC / BN / Si-CN / SiC composite material.

[0022] After maintaining the mixture for 12 to 24 hours, the impregnated SiC / BN / Si-CN / SiC / resin carbon precursor composite material is obtained.

[0023] The impregnated SiC / BN / Si-CN / SiC / resin carbon precursor composite material was placed in a high-temperature pyrolysis furnace and heated to 900~1200℃ at a heating rate of 10℃ / min.

[0024] After heat preservation for 1 hour, a porous SiC / BN / Si-CN / SiC / C composite material was obtained.

[0025] Furthermore, the porous SiC / BN / Si-CN / SiC / C composite material is subjected to silicon infiltration treatment to obtain a SiC / BN / Si-CN / SiC composite material, comprising:

[0026] The porous SiC / BN / Si-CN / SiC / C composite material is placed in a high-temperature silicon infiltration furnace, heated to 1430~1450℃, and held for 0.5~1 hour. The high-temperature silicon infiltration includes pure silicon or silicon alloy, and the silicon alloy includes one or more combinations of silicon zirconium alloy, silicon aluminum alloy, silicon molybdenum alloy, and silicon hafnium alloy.

[0027] The silicon-infiltrated composite material was cooled to room temperature in the furnace, and after being removed, the residual silicon on the surface was polished to obtain the SiC / BN / Si-CN / SiC composite material.

[0028] A method for preparing a liquid phenolic resin, wherein the liquid phenolic resin is used in the impregnation and pyrolysis treatment of a method for preparing a low-residue silicon SiC composite material, comprising:

[0029] According to the predetermined ratio, furan resin monomer, alkaline catalyst, cosolvent and third monomer are added to the reactor, stirred evenly, and heated to the first step temperature at the first heating rate, and then kept at the temperature until the first set holding time is reached to generate intermediate product.

[0030] After adding a crosslinking agent to the intermediate product, the temperature is raised to the second step temperature at the second heating rate, and then held at the temperature until the second set holding time is reached to carry out the polymerization reaction.

[0031] After the polymerization reaction is completed and the temperature is lowered, the alkali in the reaction system is neutralized, the pressure is reduced and the additives are removed to the set viscosity range to obtain the liquid resin carbon precursor.

[0032] Furthermore, the first step temperature is 50℃~85℃, the first heating rate is 1~3℃ / min, and the first set holding time is 0.5 hours~2 hours;

[0033] The second temperature step is 90℃~150℃, the second heating rate is 2~3℃ / min, and the second set holding time is 4~6 hours.

[0034] Furthermore, the furan resin monomers include aldehyde resins and phenolic resins, with the ratio of aldehyde resins to phenolic resins being 1:1 to 1:1.5, and 2% to 10% of phenolic monomers are added;

[0035] The alkaline catalyst is ammonia water, and the amount of alkaline catalyst used accounts for 0.5% to 6% of the total amount of aldehydes and phenols in the liquid phenolic resin.

[0036] Furan resins are synthetic resins whose molecular structure contains a furan ring. Furan resins include one or more combinations of furfuryl alcohol-furfural resin and furfural-acetone resin.

[0037] The amount of crosslinking agent used is 1~5%.

[0038] Furthermore, in the preparation process of liquid phenolic resin, deionized water is used as a solvent and alcohols are used as co-solvents. The alcohols include methanol or ethanol, and the amount of alcohol used is 5% to 10% of the amount of deionized water.

[0039] The pH value during the preparation of liquid phenolic resin is controlled between 8 and 10.

[0040] Compared with the prior art, the beneficial effects that at least one technical solution adopted in the embodiments of this specification can achieve include at least:

[0041] The CVI-RMI SiC / SiC composite material provided in this invention has a uniform matrix composition, low porosity, high strength, and low preparation cost. It can lay the material foundation for the engineering application of this type of material and has broad application prospects in the field of high-temperature hot-end components. Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a flowchart of the preparation method of the low residual silicon SiC composite material and the preparation method of liquid phenolic resin according to embodiments of the present invention;

[0044] Figure 2 The image shows the microstructure morphology of the CVI-RMISiC / SiC composite material prepared by the method for preparing low residual silicon SiC composite material according to the present invention.

[0045] Figure 3 This is a microstructure morphology diagram of porous carbon prepared by the liquid phenolic resin preparation method of this invention. Detailed Implementation

[0046] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] like Figure 1 As shown, the preparation method of the low residual silicon SiC composite material of this invention includes the following steps:

[0049] Step 1: Prepare SiC fiber preform.

[0050] SiC fiber bundles were prepared into SiC fiber preforms ①.

[0051] Step 2: Prepare the BN interface layer and the Si-CN composite interface layer.

[0052] The ① obtained in step one is placed in a graphite mold for shaping to obtain a fiber preform ② with a graphite mold. Then, a continuous and uniform BN interface layer is prepared on the surface of the SiC fiber in ② to obtain ③, with a BN interface layer thickness of 200nm~600nm. Then, ③ is placed in a CVI Si-CN deposition furnace to prepare a Si-CN interface layer with a thickness of 300~500nm, to obtain a porous SiC / BN / Si-CN composite material ④ with a graphite mold.

[0053] Step 3: Deposit SiC matrix using CVI process. Place the ④ obtained in step 2 into SiC vapor deposition furnace to deposit SiC matrix. After removing the graphite mold, a porous SiC / BN / Si-CN / SiC composite material ⑤ is obtained.

[0054] Step 4: Synthesize liquid phenolic resin carbon (⑥).

[0055] Liquid phenolic resin was synthesized using furan resin as a carbon precursor, deionized water as a solvent, and P123 as a crosslinking agent.

[0056] Step 5: Carbon impregnation and pyrolysis of liquid phenolic resin.

[0057] The ⑤ obtained in step three is placed in a vacuum impregnation vessel and a vacuum is drawn. When the vacuum degree is less than 100 Pa, the ⑥ obtained in step four is introduced into the vacuum impregnation vessel under pressure difference, ensuring that the ⑥ is completely immersed in the ⑤. This process is maintained for 12-24 hours to obtain the impregnated SiC / BN / Si-CN / SiC / resin carbon precursor composite material ⑦. Then, ⑦ is placed in a high-temperature pyrolysis furnace and heated to 900-1200℃ at a heating rate of 10℃ / min, and held for 1 hour to obtain a porous SiC / BN / Si-CN / SiC / C composite material ⑧.

[0058] Step 6: High-temperature silicon infiltration.

[0059] The ⑧ obtained in step 5 is placed in a high-temperature silicon infiltration furnace, heated to 1430~1450℃, held for 0.5~1 hour, cooled to room temperature with the furnace, and after being taken out, the residual silicon on the surface is polished to obtain the SiC / BN / Si-CN / SiC composite material.

[0060] Specifically, the SiC fibers in the SiC fiber bundle include new types of SiC fibers such as low-oxygen high-carbon type, near-stoichiometric type, and higher temperature resistance type. The SiC fiber preforms include SiC fiber preforms with two-dimensional lay-up structure, 2.5D woven structure, and three-dimensional multi-directional braided structure, with a fiber volume fraction of 33%~42%.

[0061] Specifically, the preparation methods for the BN interface layer include, but are not limited to, chemical vapor infiltration / deposition (CVI / CVD) and dip-coating processes. These methods can yield a continuous and uniform BN interface phase.

[0062] Specifically, the Si-CN interface layer was prepared using the CVI process.

[0063] Specifically, the graphite mold includes a female mold and a male mold. The surfaces of both the female and male molds have a first through hole with a diameter of Ф4mm~Ф6mm and a hole spacing of 8mm~12mm. The thickness of the female and male molds is 10~15mm. The four corners of the female and male molds each have a second through hole with a diameter of Ф10mm~Ф12mm and a hole edge distance of 20mm~24mm. C / C bolts and nuts matching the diameter of the through holes are used to fix the fiber preform and the male and female molds.

[0064] Specifically, the main feature of the SiC matrix in step three is that a SiC fiber preform with a graphite mold on which a BN / Si-CN multiphase interface layer has been deposited is placed into a SiC vapor deposition furnace to prepare a SiC matrix, thereby obtaining a porous SiC / BN / Si-CN / SiC composite material.

[0065] Specifically, the Si-CN interface layer in the SiC / BN / Si-CN / SiC composite material is a ceramic interface layer containing Si, C, and N elements, including but not limited to SiCN ceramics, Si3N4 ceramics, and SiBCN ceramics. The modulus of this ceramic interface layer is between that of the BN interface and the SiC matrix, aiming to achieve modulus matching of the multiphase distribution of BN / Si-CN / SiC and improve the deflection crack effect of the interface layer during the fracture process of the composite material.

[0066] Specifically, the high-temperature silicon infiltration in step six includes pure silicon or silicon alloys, such as silicon-zirconium alloys, silicon-aluminum alloys, silicon-molybdenum alloys, and silicon-hafnium alloys. Before silicon infiltration, a small amount of BN or SiC powder with a particle size of 6μm to 15μm is applied to the sample surface to increase the capillary wall effect during silicon infiltration and to prevent excessive liquid silicon or silicon alloy from adhering to the test surface during cooling, thus increasing the surface processing cost.

[0067] Low residual silicon SiC composite materials such as Figure 2 As shown.

[0068] This invention also includes a method for synthesizing liquid phenolic resin carbon, which is a modified phenolic resin. The synthesis method optimizes the molecular topology and crosslinking point spacing of the liquid phenolic resin generated under alkaline conditions by adjusting parameters such as the ratio of furan resin monomers, the type and amount of solvent, the amount of the third monomer added, and the ratio of co-solvents. This allows for the control of the pore size of the porous resin carbon during the pyrolysis process of the liquid phenolic resin carbon, which has a multi-level channel structure that facilitates the penetration of liquid silicon.

[0069] The synthesis steps of liquid phenolic resin include:

[0070] Step 1: Add furan resin monomer, alkaline catalyst, co-solvent and third monomer to the reaction vessel according to the predetermined ratio, stir evenly, and strictly control the heating rate to the first temperature step and keep it at the temperature for a certain time to generate intermediate product.

[0071] Step 2: After adding the crosslinking agent, gradually raise the temperature to the second temperature step, hold at that temperature for a certain period of time, and carry out the polymerization reaction;

[0072] Step 3: After the reaction is completed and the temperature is lowered, the alkali in the reaction system is neutralized appropriately, and the auxiliary agent is removed under reduced pressure to a suitable viscosity to obtain the liquid phenolic resin carbon precursor.

[0073] The ratio of the two furan resin monomers (including but not limited to two types of aldehyde resins and phenolic resins) is 1:1 to 1:1.5. At the same time, 2% to 10% phenol monomer can be added appropriately to adjust the molecular weight of the condensation product phenolic resin, so that it generates a liquid product.

[0074] The alkaline catalyst is ammonia water (NH3H2O), and its amount is 0.5%~6% of the total amount of aldehyde and phenol monomers.

[0075] The temperature of the liquid phenolic resin synthesis reaction needs to be controlled in stages. In the first temperature stage, the temperature is controlled within the range of 50℃ to 85℃, with a corresponding heating rate of 1 to 3℃ / min and a holding time of 0.5 to 2 hours, producing a furan resin intermediate. In the second temperature stage, the temperature is controlled within the range of 90℃ to 150℃, with a corresponding heating rate of 2 to 3℃ / min and a holding time of 4 to 6 hours.

[0076] The pH value needs to be monitored during the synthesis of liquid phenolic resin, and the pH value needs to be kept stable at 8-10 during the reaction.

[0077] Furan resins are synthetic resins containing a furan ring in their molecular structure, including but not limited to furfuryl alcohol-furfural resin and furfural-acetone resin.

[0078] In the synthesis of liquid phenolic resin, deionized water is used as the solvent, and a small amount of alcohol is added as a co-solvent. The alcohol monomers include, but are not limited to, methanol or ethanol, and the amount used is 5% to 10% of the deionized water.

[0079] The amount of crosslinking agent used in liquid phenolic resin is 1~5%.

[0080] The post-synthesis treatment steps of liquid phenolic resin include neutralizing the alkalinity in the reaction process with 0.1 M hydrochloric acid aqueous solution, and then removing the additives in the reaction system to a suitable viscosity by cooling and depressurizing, with a pressure range of 1.5~2 kPa.

[0081] The porous carbon produced, such as Figure 3 As shown.

[0082] Using two examples, the preparation methods of low-residual silicon SiC composite materials and liquid phenolic resin are further explained.

[0083] Example 1:

[0084] In this embodiment, a 2.5D CVI-RMISiC / SiC composite material was prepared. First, a graphite mold was designed based on the size of the fiber preform. A BN interface layer was prepared using boron trichloride, hydrogen, ammonia, and argon as gas sources. A SiCN interface layer was prepared using trichloromethylsilane, ammonia, argon, and hydrogen as gas sources. A SiC matrix was prepared using trichloromethylsilane, hydrogen, and argon as gas sources. Liquid phenolic resin was synthesized using aldehydes and alcohols as carbon precursors, deionized water as a solvent, and P123 as a crosslinking agent. The liquid phenolic resin was impregnated under vacuum pressure and then pyrolyzed. Finally, silicon infiltration was performed to obtain the SiC / SiC composite material.

[0085] Includes the following steps:

[0086] (1) Preparation of 2.5D silicon carbide fiber preform: 0.5k low oxygen high carbon type silicon carbide fiber is used as reinforcement and 2.5D silicon carbide fiber preform is prepared as a whole by weaving. The warp to weft ratio of 2.5D fiber preform is 7:6, the fiber volume fraction is 40%, and the fiber preform size is 270×180×4mm (length×width×thickness).

[0087] (2) The 2.5DSiC fiber preform is then inserted into the graphite mold. The graphite mold includes a female mold and a male mold. Both the male and female molds have through holes with a diameter of Ф4mm on their surfaces, with a hole spacing of 8mm. The thickness of the graphite molds for the female and male molds is 10mm. The four corners of the graphite molds for the female and male molds have through holes with a diameter of Ф12mm, with a hole edge distance of 24mm. The fiber preform and the male and female graphite molds are fixed with C / C bolts and nuts of the corresponding size.

[0088] (3) Preparation of BN / SiCN interface layer: The 2.5DSiC fiber preform with graphite mold was placed in the BN deposition furnace. The furnace was evacuated to a vacuum level below 50 Pa. The temperature was then raised to 300℃ and held for 1 h. The temperature was then raised to 1000℃ and held for 1 h. The BN deposition gas source was introduced: boron trichloride, ammonia, argon and hydrogen. The purity of boron trichloride, ammonia and argon was 99.99%, 99.999% and 99.999% respectively. The specific deposition process parameters were: the flow rates of boron trichloride, ammonia, argon and hydrogen were 0.2 L / min, 1 L / min, 2 L / min and 2 L / min respectively; the deposition temperature was 1000℃; the deposition pressure was 1.5 KPa; and the deposition time was 8 h. The 2.5DSiC fiber preform with graphite mold containing BN interface layer was obtained. The SiC fiber preform with the deposited BN interface layer was then placed together with the graphite mold into a SiCN vapor deposition furnace. The furnace was evacuated to a vacuum level below 50 Pa, and then the temperature was raised to 300℃ and held for 1 hour. The temperature was then raised to 1000℃ and held for 1 hour. The SiCN deposition gas source was introduced: boron trichloride, ammonia, argon, and hydrogen. The purity of trichloromethylsilane was 96%, the purity of ammonia was 99.99%, the purity of argon was 99.999%, and the purity of hydrogen was 99.999%. The deposition temperature was 1000℃, the deposition pressure was 1.5 kPa, and the deposition time was 15 hours.

[0089] (4) CVI SiC substrate: The 2.5DSiC fiber preform with deposited BN / SiCN composite interface layer was placed together with the graphite mold in the SiC vapor deposition furnace. The deposition system was trichloromethylsilane-hydrogen-argon, with trichloromethylsilane purity of 96%, hydrogen purity of 99.999%, and argon purity of 99.999%. The mass ratio of the three was 1:5:5. The deposition temperature was 1050℃, the pressure was 2000Pa, and the deposition time was 140h. The graphite mold was then removed.

[0090] (5) Synthesis of liquid resin carbon: Aldehydes and alcohols were used as carbon precursors, deionized water as solvent, and P123 as crosslinking agent to synthesize liquid phenolic resin. The specific synthesis route is as follows: 500g furfural, 600g furfuryl alcohol, and 50g phenol were weighed and added to the reaction system, along with 10L deionized water and 0.5L ethanol. Ammonia was added dropwise to the system to adjust the pH to 8-10. Then, the reactor was sealed with an inert gas. Under mechanical stirring, the temperature was increased to 80℃ at a rate of 1.5℃ / min and held for 1 hour. Then, the temperature was increased to 120℃ at a rate of 2.5℃ / min and held for 5 hours. After the reaction was completed, 110g of P123 crosslinking agent was added, the pressure of the reaction system was reduced to 1.5kPa, and the water in the reaction system was removed to finally obtain liquid resin carbon.

[0091] (6) Impregnating and pyrolyzing liquid resin carbon: The 2.5DSiC fiber preform deposited with BN / SiCN / SiC was placed in a vacuum impregnation device. The vacuum impregnation device was evacuated using a vacuum pump. When the pressure inside the vacuum impregnation device was less than 100 Pa, the liquid resin carbon precursor impregnation solution was introduced into the vacuum impregnation device through a stainless steel pipeline. Finally, the fiber preform was completely submerged in the polymer precursor impregnation solution and kept for 24 hours. The impregnated 2.5DSiC fiber preform was placed in a graphite mold and placed in a high-temperature pyrolysis furnace. When the pressure was evacuated to less than 100 Pa, the temperature was increased from room temperature to 1200℃ at a heating rate of 10℃ / min and pyrolyzed at high temperature for 1 hour. The graphite mold was then removed.

[0092] (7) High-temperature silicon infiltration: The SiC / BN / SiCN / C that has undergone high-temperature pyrolysis is placed in a high-temperature silicon infiltration furnace, and silicon powder is spread on the surface. When the vacuum is reduced to less than 100 Pa, the temperature is increased to 1200℃ at 10℃ / min and held for 0.5 hours. Then, the temperature is increased to 1400℃ at 5℃ / min and held for 20 minutes. Finally, the temperature is increased to 1430℃ at 3℃ / min and silicon infiltration is carried out for 0.5 hours. The furnace is then cooled down. The CVI-RMISiC / SiC composite material is obtained.

[0093] Example 2:

[0094] In this embodiment, 2DCVI-RMISiC / SiC composite material was prepared. First, a graphite mold was designed based on the size of the fiber preform. A BN interface layer was prepared using boron trichloride, hydrogen, ammonia, and argon as gas sources. A Si3N4 interface layer was prepared using silicon tetrachloride, ammonia, argon, and hydrogen as gas sources. A SiC matrix was prepared using trichloromethylsilane, hydrogen, and argon as gas sources. Liquid phenolic resin was synthesized using aldehydes and alcohols as carbon precursors, deionized water as a solvent, and P123 as a crosslinking agent. The liquid phenolic resin was impregnated under vacuum pressure and then pyrolyzed. Finally, silicon infiltration was performed to obtain the SiC / SiC composite material.

[0095] Includes the following steps:

[0096] (1) Preparation of 2D silicon carbide fiber preform: 0.5k low oxygen high carbon type silicon carbide fiber is used as reinforcement. Silicon carbide fiber cloth is prepared by 0 / 90° weaving method. The multi-layer silicon carbide fiber cloth is stacked to obtain 2D fiber preform. The warp to weft ratio is 1:1, the fiber volume fraction is 40%, and the fiber preform size is 270×180×4mm (length×width×thickness).

[0097] (2) The 2D SiC fiber preform is then inserted into the graphite mold. The graphite mold includes a female mold and a male mold. Both the male and female molds have through holes with a diameter of Ф4mm on their surfaces, with a hole spacing of 8mm. The thickness of the graphite molds for the female and male molds is 10mm. The four corners of the graphite molds for the female and male molds have through holes with a diameter of Ф12mm, with a hole edge distance of 24mm. The fiber preform and the graphite molds for the male and female molds are fixed with C / C bolts and nuts of the corresponding size.

[0098] (3) Preparation of BN / Si3N4 interface layer: The 2D SiC fiber preform with graphite mold was placed in the BN deposition furnace. The furnace was evacuated to a vacuum level below 50 Pa. The temperature was then raised to 300℃ and held for 1 h. The temperature was then raised to 1000℃ and held for 1 h. The BN deposition gas source was introduced: boron trichloride, ammonia, argon and hydrogen. The purity of boron trichloride, ammonia and argon was 99.99%, 99.999% and 99.999% respectively. The specific deposition process parameters were: the flow rates of boron trichloride, ammonia, argon and hydrogen were 0.2 L / min, 1 L / min, 2 L / min and 2 L / min respectively; the deposition temperature was 1000℃; the deposition pressure was 1.5 KPa; and the deposition time was 8 h. The 2D SiC fiber preform with graphite mold containing BN interface layer was obtained. The SiC fiber preform with the deposited BN interface layer was then placed together with the graphite mold into a Si3N4 vapor deposition furnace. The furnace was evacuated to a vacuum level below 50 Pa, and then the temperature was raised to 300℃ and held for 1 hour. The temperature was then raised to 800℃ and held for 1 hour. The Si3N4 deposition gas source was introduced: silicon tetrachloride, ammonia, argon, and hydrogen. The purity of silicon tetrachloride was 96%, ammonia was 99.99%, argon was 99.999%, and hydrogen was 99.999%. The deposition temperature was 800℃, the deposition pressure was 1.5 kPa, and the deposition time was 15 hours.

[0099] (4) CVI SiC substrate: The 2D SiC fiber preform with deposited BN / Si3N4 composite interface layer is placed together with the graphite mold in the SiC vapor deposition furnace. The deposition system is trichloromethylsilane-hydrogen-argon, wherein the purity of trichloromethylsilane is 96%; the purity of hydrogen is 99.999%; the purity of argon is 99.999%; the mass ratio of the three is 1:5:5, the deposition temperature is 1050℃, the pressure is 2000Pa, the deposition time is 140h, and the graphite mold is removed.

[0100] (5) Synthesis of liquid resin carbon: Aldehydes and alcohols were used as carbon precursors, deionized water as solvent, and P123 as crosslinking agent to synthesize liquid phenolic resin. The specific synthesis route is as follows: 500g furfural, 600g furfuryl alcohol, and 50g phenol were weighed and added to the reaction system, along with 10L deionized water and 0.5L ethanol. Ammonia was added dropwise to the system to adjust the pH to 8-10. Then, the reactor was sealed with an inert gas. Under mechanical stirring, the temperature was increased to 80°C at a rate of 1.5°C / min and held for 1 hour. Then, the temperature was increased to 120°C at a rate of 2.5°C / min and held for 5 hours. After the reaction was completed, 110g of P123 crosslinking agent was added, the pressure of the reaction system was reduced to 1.5kPa, and the water in the reaction system was removed to finally obtain liquid resin carbon.

[0101] (6) Impregnating with liquid resin carbon and then pyrolyzing: The 2D SiC fiber preform deposited with BN / Si3N4 / SiC was placed in a vacuum impregnation device. The vacuum impregnation device was evacuated using a vacuum pump. When the pressure inside the vacuum impregnation device was less than 100 Pa, the liquid resin carbon precursor impregnation solution was introduced into the vacuum impregnation device through a stainless steel pipeline. Finally, the fiber preform was completely submerged in the polymer precursor impregnation solution and kept for 24 hours. The impregnated 2D SiC fiber preform was placed in a graphite mold and then placed in a high-temperature pyrolysis furnace. When the pressure was evacuated to less than 100 Pa, it was heated from room temperature to 1200 °C at a heating rate of 10 °C / min and pyrolyzed at high temperature for 1 hour. The graphite mold was then removed.

[0102] (7) High-temperature silicon infiltration: The SiC / BN / Si3N4 / C that has undergone high-temperature pyrolysis is placed in a high-temperature silicon infiltration furnace, and silicon powder is spread on the surface. When the vacuum is reduced to less than 100 Pa, the temperature is increased to 1200℃ at 10℃ / min and held for 0.5 hours. Then, the temperature is increased to 1400℃ at 5℃ / min and held for 20 minutes. Finally, the temperature is increased to 1430℃ at 3℃ / min and silicon infiltration is carried out for 0.5 hours. The furnace is then cooled down. CVI-RMI SiC / SiC composite material is obtained.

[0103] Beneficial effects of the embodiments of the present invention:

[0104] Unlike traditional methods that use phenolic resin as a carbon source, resulting in oxygen-containing, amorphous, and blocky distribution of the resin carbon leading to poor melt penetration channels, insufficient reaction between the phenolic resin carbon and molten silicon, and the SiC matrix only forming at the interface between the phenolic resin carbon and molten silicon, which creates carbon-rich and silicon-rich regions in the composite material, leading to low density, high porosity, and poor mechanical properties, this invention utilizes synthesized liquid resin carbon as a precursor for impregnation and pyrolysis to obtain a porous carbon precursor suitable for the silicon infiltration process. This avoids the existence of silicon-rich and carbon-rich regions caused by poor silicon infiltration channels. In addition, the use of a Si-CN interface can protect the BN interface layer and SiC fibers from erosion by molten silicon, ensuring the full utilization of the interface's "mechanical fuse" function and the maintenance of fiber in-situ strength. Meanwhile, the modulus of the Si-CN ceramic interface layer is between that of the BN interface and the SiC matrix. The sequential distribution of BN / Si-CN / SiC can achieve a gradient increase in modulus, alleviate the modulus mismatch between BN and the SiC matrix, and improve the deflection effect of the interface layer during the fracture process of the composite material. The use of the BN / Si-CN multiphase interface layer realizes the protection of SiC fibers during the silicon infiltration process. Based on the principle of polycondensation reaction, a new resin is synthesized, and after medium-temperature pyrolysis, porous carbon with specific pore size and interconnected open pore characteristics is obtained, which changes the dense bulk structure characteristics of phenolic resin carbon, provides a favorable channel for the infiltration of molten silicon, and enhances the RMI reaction efficiency. Finally, the CVI-RMI SiC / SiC composite material matrix provided in this embodiment has uniform composition, low porosity, high strength, and low preparation cost, which can lay the material foundation for the engineering application of this type of material and has broad application prospects in the field of high-temperature hot-end components.

[0105] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical solutions, and technical solutions in this invention can be freely combined and used.

Claims

1. A method for preparing a low-residual silicon SiC composite material, characterized in that, include: A SiC fiber preform was prepared using SiC fiber bundles, and the SiC fiber preform was placed in a graphite mold for shaping to obtain a fiber preform with a graphite mold. A continuous and uniform BN interface layer is prepared on the surface of the SiC fibers of the fiber preform to obtain a fiber preform containing the BN interface layer. Based on the fiber preform containing the BN interface layer, a Si-CN interface layer is prepared to obtain a porous SiC / BN / Si-CN composite material with a graphite mold. Based on the porous SiC / BN / Si-CN composite material with graphite mold, a SiC matrix is ​​deposited to obtain a porous SiC / BN / Si-CN / SiC composite material. A liquid resin is prepared, and the porous SiC / BN / Si-CN / SiC composite material is impregnated and pyrolyzed using the liquid resin to obtain a porous SiC / BN / Si-CN / SiC / C composite material. Preparation of liquid resin includes: According to the predetermined ratio, furan resin monomer, alkaline catalyst, cosolvent and third monomer are added to the reactor, stirred evenly, and heated to the first step temperature at the first heating rate, and then kept at the temperature until the first set holding time is reached to generate intermediate product. The first step temperature is 50℃~85℃, the first heating rate is 1~3℃ / min, and the first set holding time is 0.5 hours~2 hours; The furan resin monomers include aldehydes and alcohols, with the ratio of aldehydes to alcohols being 1:1 to 1:1.5, and phenol monomers are added at 2% to 10% of the total amount of furan resin monomers; the alkaline catalyst is ammonia water, and the amount of the alkaline catalyst is 0.5% to 6% of the total amount of aldehyde and alcohol monomers in the liquid resin; the furan resin is a synthetic resin containing a furan ring in its molecular structure; the amount of crosslinking agent is 11.5% of the mass percentage of the furan resin monomers, and the crosslinking agent is P123; After adding a crosslinking agent to the intermediate product, the temperature is raised to the second step temperature at the second heating rate, and then kept at the temperature until the second set holding time is reached to carry out the polymerization reaction. The second step temperature is 90℃~150℃, the second heating rate is 2~3℃ / min, and the second set holding time is 4~6 hours; After the polymerization reaction is completed and the temperature is lowered, the alkali in the reaction system is neutralized, the pressure is reduced and the additives are removed to the set viscosity range to obtain the liquid resin carbon precursor. The porous SiC / BN / Si-CN / SiC / C composite material is subjected to silicon infiltration treatment to obtain the SiC / BN / Si-CN / SiC composite material.

2. The method for preparing the low-residual silicon SiC composite material according to claim 1, characterized in that, Based on the fiber preform containing the BN interface layer, a Si-CN interface layer is prepared to obtain a porous SiC / BN / Si-CN composite material with a graphite mold, comprising: The fiber preform containing the BN interface layer is placed in a CVI Si-CN deposition furnace; A porous SiC / BN / Si-CN composite material with a graphite mold is obtained by preparing a Si-CN interface layer using the CVI process. The thickness of the BN interface layer is 200 nm to 600 nm, and the thickness of the Si-CN interface layer is 300 nm to 500 nm. The Si-CN interface layer is a ceramic interface layer containing Si, C, and N elements, including but not limited to one or more combinations of SiCN ceramics and SiBCN ceramics.

3. The method for preparing the low-residual silicon SiC composite material according to claim 1, characterized in that, The graphite mold includes a female mold and a male mold. The surfaces of the female mold and the male mold are provided with a first through hole with a diameter of Ф4mm~Ф6mm. The spacing between the first through holes is 8mm~12mm. The thickness of the female mold and the male mold is 10~15mm. The four corners of the female mold and the male mold are respectively provided with a second through hole with a diameter of Ф10mm~Ф12mm. The edge distance of the second through hole is 20mm~24mm.

4. The method for preparing the low-residual silicon SiC composite material according to claim 1, characterized in that, Based on the porous SiC / BN / Si-CN composite material with graphite mold, a SiC matrix is ​​deposited to obtain a porous SiC / BN / Si-CN / SiC composite material, comprising: The SiC matrix was prepared using the CVI process, and the porous SiC / BN / Si-CN composite material with a graphite mold was placed in a SiC vapor deposition furnace to deposit the SiC matrix. After removing the graphite mold, a porous SiC / BN / Si-CN / SiC composite material is obtained.

5. The method for preparing the low-residual silicon SiC composite material according to claim 1, characterized in that, The porous SiC / BN / Si-CN / SiC composite material is impregnated and pyrolyzed using liquid resin to obtain a porous SiC / BN / Si-CN / SiC / C composite material, comprising: The porous SiC / BN / Si-CN / SiC composite material was placed in a vacuum impregnation vessel and a vacuum was drawn. When the vacuum degree of the vacuum impregnation vessel is less than 100 Pa, the liquid resin is introduced into the vacuum impregnation vessel under the action of pressure difference, so that the liquid resin completely impregnates the porous SiC / BN / Si-CN / SiC composite material. After maintaining the mixture for 12-24 hours, the impregnated SiC / BN / Si-CN / SiC resin carbon precursor composite material is obtained. The impregnated SiC / BN / Si-CN / SiC resin carbon precursor composite material is placed in a high-temperature pyrolysis furnace and heated to 900~1200℃ at a heating rate of 10℃ / min. After heat preservation for 1 hour, a porous SiC / BN / Si-CN / SiC / C composite material was obtained.

6. The method for preparing the low-residual silicon SiC composite material according to claim 1, characterized in that, The porous SiC / BN / Si-CN / SiC / C composite material is subjected to silicon infiltration treatment to obtain a SiC / BN / Si-CN / SiC composite material, comprising: The porous SiC / BN / Si-CN / SiC / C composite material is placed in a high-temperature silicon infiltration furnace, heated to 1430~1450℃, and held for 0.5~1 hour. The high-temperature silicon infiltration includes pure silicon or silicon alloy, and the silicon alloy includes one or more combinations of silicon zirconium alloy, silicon aluminum alloy, silicon molybdenum alloy, and silicon hafnium alloy. The porous SiC / BN / Si-CN / SiC composite material was cooled to room temperature in the furnace, and after being removed, the residual silicon on the surface was polished to obtain the SiC / BN / Si-CN / SiC composite material.

7. The method for preparing the low-residual silicon SiC composite material according to claim 1, characterized in that, In the preparation process of the liquid resin, deionized water is used as a solvent and alcohols are used as a co-solvent. The alcohols include methanol or ethanol, and the amount of alcohol used is 5% to 10% of the amount of deionized water. The pH value is controlled between 8 and 10 during the preparation process of the liquid resin.

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