Ultra-high temperature ceramic modified C / C composite material and its preparation method and application

Abstract

The present invention discloses an ultrahigh-temperature ceramic-modified C / C composite material, its preparation method, and application, relating to the field of ultrahigh-temperature materials technology. The method comprises obtaining a resin slurry, a free silicon slurry, and a ceramic particle slurry; sequentially applying the resin slurry, free silicon slurry, and ceramic particle slurry to a carbon cloth surface to obtain a multi-layered carbon cloth; stacking the multi-layered carbon cloth into a composite body using a binder; and placing the cured composite body into a mold to obtain the ultrahigh-temperature ceramic-modified C / C composite material. The present invention effectively reduces carbon fiber damage and improves interfacial bonding by introducing a transition resin layer.

Description

Technical Field

[0001] The present invention relates to the technical field of ultrahigh temperature materials, and in particular to an ultrahigh temperature ceramic modified C / C composite material and a preparation method and application thereof. Background Art

[0002] Carbon / carbon (C / C) composite material is a single element composite material with carbon fiber and its fabric as reinforcement and pyrolytic carbon as matrix. It is a multiphase material with a turbostratic graphite structure and has low density (density is generally less than 2g / cm 3 ), low thermal expansion coefficient (about 1-2×10 -6 C / C composites offer a unique combination of high-temperature properties, high strength / K, high specific strength, excellent high-temperature mechanical properties, and resistance to high-temperature thermal cycling. Their unique high-temperature performance is unmatched by other structural materials, making them ideal structural materials for the hot-end components of hypersonic vehicles. However, the strong oxidation sensitivity of C / C composites significantly limits their application in high-temperature aerobic environments. Therefore, improving the oxidation resistance of C / C composites is a key issue in enhancing their stability in high-temperature aerobic environments.

[0003] Ultrahigh-temperature ceramics (UHTCs) are transition metal compounds with melting points above 3000°C. They primarily include transition metal borides, carbides, and nitrides, such as HfB2, ZrB2, TaB2, TiB2, ZrC, HfC, TiC, TaC, ZrN, HfN, TiN, and TaN. UHTCs possess metal-like properties, such as excellent electrical and thermal conductivity. Strong covalent bonds give them high melting points, high stiffness, and hardness, as well as excellent resistance to oxidation and ablation at high temperatures. Therefore, incorporating UHTCs into C / C composites could help overcome the high-temperature oxidation sensitivity of C / C composites.

[0004] Currently, conventional methods for preparing UHTCs-modified C / C composites primarily include polymer impregnation pyrolysis (PIP), reactive melt infiltration (RMI), chemical vapor infiltration (CVI), and the traditional solid-phase method. However, the PIP process has a long preparation cycle and struggles to produce high-density materials; the RMI process suffers from excessively high reaction temperatures, which can severely damage the carbon fibers and make it difficult to obtain composites with high UHTCs content; and the CVI process has a long production cycle, high equipment requirements, high production costs, and difficult process control. The traditional solid-phase method involves vacuum impregnation of a ceramic slurry into a carbon fiber preform, followed by high-temperature treatment or hot-pressing sintering to produce UHTCs-modified C / C composites. While this process offers the advantages of ease of operation, it currently suffers from drawbacks such as uneven ceramic phase distribution and the accumulation of ceramic particles on the surface, hindering the practical application of the material. ZrC-SiC-modified C / C composites have been successfully prepared using the RMI process. However, the high reaction temperature during the preparation process causes damage to the carbon fibers, resulting in brittle fracture of the composite. ZrC and SiC were introduced into C / C composites using the PIP process. After multiple curing and cracking cycles, the modified composites still contained a certain number of closed pores, indicating incomplete densification. C / C-ZrC composites were successfully prepared using the CLVD process, but the preparation cycle exceeded two weeks, the equipment requirements were high, and the preparation process was complex. Summary of the Invention

[0005] To address the deficiencies in the aforementioned background technology, the present invention addresses the prior art problem of high reaction temperatures in the modification of C / C composite materials using UHTCs, which damage the carbon fibers and cause brittle fracture in the composite materials. The present invention provides an ultrahigh-temperature ceramic-modified C / C composite material, a preparation method, and applications thereof. This method not only shortens the composite material preparation cycle but also enables control over the ceramic components and their content, resulting in excellent designability. This can provide further insights into the subsequent structural design of composite materials for different usage environments and application requirements.

[0006] In order to achieve the above object, the first aspect of the present invention provides an ultrahigh temperature ceramic modified C / C composite material, comprising the following steps:

[0007] Obtaining resin slurry, free silicon slurry and ceramic particle slurry;

[0008] The resin slurry, the free silicon slurry and the ceramic particle slurry are sequentially applied to the surface of the carbon cloth to obtain a multi-layer coated carbon cloth; wherein each coated layer is dried;

[0009] The carbon cloth coated with multiple layers of coating is stacked into a composite material body by using an adhesive, the body is vacuum treated, and then dried at 80-100° C. for 1-2 hours to obtain a cured composite material body;

[0010] After the cured composite body is placed in a mold, the temperature is raised to 1700-1900°C at a rate of 10-15°C / min under vacuum and kept at this temperature for 30-60 minutes. At the same time, during the heating process from room temperature to 1200°C, pressure is gradually applied to the cured composite body until the sample pressure reaches 30-40 MPa. The pressure is maintained until the hot pressing mold cools to room temperature to obtain an ultra-high temperature ceramic modified C / C composite material.

[0011] Preferably, the drying temperature for each coating layer is 60-80° C. and the drying time is 10-15 minutes. After the ceramic particle slurry is coated, the drying time is 4-6 hours.

[0012] Preferably, the resin slurry is prepared by adding a certain amount of phenolic resin particles to an anhydrous ethanol solution and stirring; the free silicon slurry is prepared by adding phenolic resin particles and Si powder in a certain molar ratio to an anhydrous ethanol solution and stirring; the ceramic particle slurry is prepared by adding ceramic powder, sintering aid and phenolic resin particles in a certain molar ratio to an anhydrous ethanol solution and stirring.

[0013] Preferably, the coating on the surface of the carbon cloth includes one or more ceramic particle slurries, wherein the ceramic powder in each ceramic particle slurry is one or more of HfB2, ZrB2, HfSi2, SiC, and Si.

[0014] Preferably, after the resin slurry is coated on the surface of the carbon cloth, a resin layer with a thickness of 25 to 50 μm is formed on the surface of the carbon cloth after drying; then the free silicon slurry is coated on the resin layer, and a free silicon layer with a thickness of 15 to 30 μm is formed after drying; then the ceramic particle slurry is coated on the free silicon coating, and a ceramic layer with a thickness of 100 to 150 μm is formed after drying; thus, a carbon cloth coated with multiple layers of coating is obtained.

[0015] Preferably, the vacuum treatment is to place the green body in a vacuum drying oven for vacuum treatment, and maintain the vacuum state for 15 to 30 minutes.

[0016] Preferably, after the cured composite material body is placed in the mold, -4 The subsequent sintering is carried out in a vacuum environment of Pa, wherein the mold is a graphite mold.

[0017] Preferably, after the cured composite material green body is placed in a mold, the mold is protected around with graphite paper, and placed in a hot pressing sintering furnace, and the distance between the mold upper pressing head and the mold is maintained at 15 to 20 mm.

[0018] A second aspect of the present invention provides an ultrahigh temperature ceramic modified C / C composite material.

[0019] A third aspect of the present invention provides an application of an ultra-high temperature ceramic modified C / C composite material in a hot end component of a hypersonic aircraft.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides an ultra-high temperature ceramic modified C / C composite material and its preparation method and application, which have the following effects:

[0022] (1) Short preparation cycle: The traditional CVI preparation process cycle is about two weeks, while the preparation cycle of the present invention is only about 2 days, which is shorter; (2) Less damage to carbon fiber: Compared with the traditional RMI preparation process, the RMI process causes the ceramic matrix to react with the carbon fiber due to its higher preparation temperature, thereby damaging the carbon fiber, while the introduction of the transition resin layer in this process effectively reduces the damage to the carbon fiber, and the reaction between the resin layer and the transition silicon layer improves the interface bonding; (3) Realizes the control of the ceramic composition and distribution inside the composite material, with strong designability: Compared with the traditional solid phase method, the composition and ratio of the ceramic in the slurry can be adjusted according to actual conditions, and the distribution of the ceramic layer can be controlled according to the thickness change and mass change during the coating process. Therefore, the coating composition and structure of the carbon cloth surface are highly designable, and the composite material can be structurally designed according to different usage environments and actual engineering needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the present invention.

[0024] Figure 2 This is a comparison chart of the room temperature bending properties of the HfB2-SiC modified C / C composite material prepared by the RMI process and the present invention.

[0025] Figure 3 These are the cross-sectional SEM photos of the HfB2-SiC modified C / C composite material prepared in the present invention and its EDS analysis results.

[0026] Figure 4 This is an SEM photo of the HfB2-SiC ceramic and SiC ceramic co-modified C / C composite material prepared in the present invention.

[0027] Figure 5The changes in the ablation rate at each stage and the total ablation rate of the sample after ablation for 600s at a flow rate of 2.38MW before and after the introduction of the silicon transition layer into the HfB2-SiC modified C / C composite material prepared by the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below with reference to specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0029] The present invention provides a method for preparing a high-temperature ceramic-modified C / C composite material, which is mainly based on a hot-pressing sintering auxiliary slurry impregnated carbon cloth lamination process. First, a carbon fiber plain-weave carbon cloth is taken, and a phenolic resin coating and a silicon-phenolic resin coating of a certain thickness are brushed on the surface of the carbon cloth to obtain a pretreated carbon cloth. Next, the ceramic slurry that has been thoroughly stirred and ultrasonically treated is evenly applied to the pretreated carbon cloth to obtain a ceramic-coated carbon cloth. On the one hand, the resin layer introduced during the pretreatment process carbonizes under high-temperature treatment to form pyrolytic carbon, which reacts with free silicon to form SiC. The formation of SiC not only prevents free silicon and the ceramic layer from corroding the carbon fibers, but also improves the interlayer bonding strength between the ceramic layer and the carbon cloth layer through chemical bonding, solving the interlayer bonding problem of the sample. On the other hand, sintering aids with optimized content and particle size are added to the ceramic slurry. These sintering aids promote the sintering of the ceramic and reduce the pore defects within the ceramic layer during the hot-pressing sintering process, achieving densification of the ultra-high-temperature ceramic-modified C / C composite material. Next, a certain number of ceramic-coated carbon cloth layers are stacked at room temperature using a polyvinyl alcohol (PVA) aqueous solution to form a green body. PVA aqueous solution exhibits excellent bonding properties at room temperature and, at high temperatures, can be converted into pyrolytic carbon, reacting with free silicon, thereby enhancing the interlayer adhesion of the laminated specimen. Therefore, PVA aqueous solution is used as a binder. Finally, the dried green body is placed in a graphite mold and hot-pressed for sintering. This hot-pressing process provides the energy required for solid-phase diffusion of the ceramic particles, resulting in sintering and densification, ultimately producing a molded specimen.

[0030] The present invention provides a method for preparing an ultra-high temperature ceramic modified C / C composite material, comprising the following steps:

[0031] Obtaining resin slurry, free silicon slurry and ceramic particle slurry;

[0032] The resin slurry, the free silicon slurry and the ceramic particle slurry are sequentially applied to the surface of the carbon cloth to obtain a multi-layer coated carbon cloth; wherein each coated layer is dried;

[0033] The carbon cloth coated with multiple layers of coating is stacked into a composite material body by using an adhesive, the body is vacuum treated, and then dried at 80-100° C. for 1-2 hours to obtain a cured composite material body;

[0034] After the cured composite body is placed in a mold, the temperature is raised to 1700-1900°C at a rate of 10-15°C / min under vacuum and kept at this temperature for 30-60 minutes. At the same time, during the heating process from room temperature to 1200°C, pressure is gradually applied to the cured composite body until the sample pressure reaches 30-40 MPa. The pressure is maintained until the hot pressing mold cools to room temperature to obtain an ultra-high temperature ceramic modified C / C composite material.

[0035] The drying temperature for each coating layer is 60-80° C. and the drying time is 10-15 minutes. After the ceramic particle slurry is coated, the drying time is 4-6 hours.

[0036] The resin slurry is prepared by adding a certain amount of phenolic resin particles to an anhydrous ethanol solution and stirring; the free silicon slurry is prepared by adding phenolic resin particles and Si powder according to a certain molar ratio to an anhydrous ethanol solution and stirring; the ceramic particle slurry is prepared by adding ceramic powder, sintering aid and phenolic resin particles according to a certain molar ratio to an anhydrous ethanol solution and stirring.

[0037] The surface of the carbon cloth is coated with one or more ceramic particle slurries, wherein the ceramic powder in each ceramic particle slurry is one or more of HfB2, ZrB2, HfSi2, SiC, and Si. This process is also applicable to other ultra-high temperature ceramics, such as ZrC, HfC, TaC, ZrN, HfN, TaN, etc.

[0038] According to the present invention, after a resin slurry is applied to the surface of a carbon cloth, a resin layer with a thickness of 25 to 50 μm is formed on the surface of the carbon cloth after drying; a free silicon slurry is then applied to the resin layer, and a free silicon layer with a thickness of 15 to 30 μm is formed after drying; subsequently, a ceramic particle slurry is applied to the free silicon coating, and a ceramic layer with a thickness of 100 to 150 μm is formed after drying; thus, a carbon cloth coated with multiple layers of coating is obtained.

[0039] The vacuum treatment is to place the green body into a vacuum drying oven for vacuum treatment, and maintain the vacuum state for 15 to 30 minutes.

[0040] The composite material green body after curing is placed in a mold and then sintered in a vacuum environment of 1 to 5×10-4 Pa, wherein the mold is a graphite mold.

[0041] After the cured composite material green body is placed in the mold, the mold is protected with graphite paper around it and placed in a hot pressing sintering furnace, and the distance between the mold upper pressure head and the mold is maintained at 15 to 20 mm.

[0042] The present invention provides an ultra-high temperature ceramic modified C / C composite material prepared by the above method.

[0043] The present invention provides an application of an ultra-high temperature ceramic modified C / C composite material in a hot end component of a hypersonic aircraft.

[0044] In one embodiment, the present invention provides a method for preparing a high temperature ceramic modified C / C composite material, see Figure 1 As shown, the specific process is:

[0045] Step 1: Prepare slurry: prepare resin slurry, free silicon slurry and ceramic particle slurry respectively. The specific method is: add a certain amount of phenolic resin particles to anhydrous ethanol solution, and obtain resin slurry after sufficient stirring (15-30 minutes); add phenolic resin particles and Si powder to anhydrous ethanol solution in a certain molar ratio, and stir evenly (30-45 minutes) to obtain free silicon slurry; add ceramic powder (one or more such as HfB2, ZrB2, SiC, etc.), sintering aid and phenolic resin in a certain molar ratio to anhydrous ethanol solution, and obtain ceramic particle slurry after sufficient stirring and ultrasonication (45-60 minutes).

[0046] Step 2: Coating: Use 3K two-dimensional plain carbon fiber cloth with the brand name T300, apply a phenolic resin coating with a thickness of 25-50μm on the surface of the carbon cloth, place it in a 60-80℃ oven to dry (10-15 minutes), apply a free silicon coating with a thickness of 15-30μm on the surface of the resin-coated carbon cloth, place it in a 60-80℃ oven to dry for 10-15 minutes, and then apply a ceramic coating. After the ceramic layer reaches a thickness of 100-150μm, place it in a 60-80℃ oven to dry for 4-6 hours to obtain a multi-layer coated carbon cloth.

[0047] Step 3: Use PVA solution to bond the multi-layer coated carbon cloth and stack it into a composite material blank, place the blank in a vacuum drying oven for vacuum treatment, maintain the vacuum state for 15-30 minutes, take it out and place it in an 80-100℃ oven for 1-2 hours to achieve the curing of the resin inside the composite material blank.

[0048] Step 4: Place the cured composite material body into a high-strength graphite mold, protect the mold with graphite paper, and keep the distance between the mold head and the mold at 15-20mm.

[0049] Step 5: Place the processed hot pressing mold into the hot pressing sintering furnace and sinter it under high vacuum (1-5×10 -4 Pa) at a rate of 10-15℃ / min to 1700-1900℃, and keep warm for 30-60min. In the process of heating from room temperature to 1200℃, gradually apply pressure until the sample pressure reaches 30-40MPa. After the holding time is over,

[0050] The power is then turned off to cool the sample, and the pressure is maintained until the sample is removed. After the hot pressing mold cools to room temperature, it can be removed to obtain a high-temperature ceramic modified C / C composite material.

[0051] The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explain the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are encompassed within the scope of protection that the present invention is intended to protect.

[0052] It should be noted that the experimental methods used in the present invention are all conventional methods unless otherwise specified; the reagents and materials used are all commercially available unless otherwise specified.

[0053] Example 1

[0054] A method for preparing a high-temperature ceramic-modified C / C composite material comprises the following steps:

[0055] Step 1: Prepare slurry: prepare resin slurry, free silicon slurry and ceramic particle slurry respectively. The specific method is: add 10g of phenolic resin particles to 100g of anhydrous ethanol solution, and obtain resin slurry after sufficient stirring (20min); add phenolic resin particles and Si powder to anhydrous ethanol solution in a molar ratio of 1:5, and stir evenly (30min) to obtain free silicon slurry; add ceramic powder and phenolic resin with SiC and Si in a molar ratio of 4:1 to anhydrous ethanol solution, and obtain ceramic particle slurry after sufficient stirring and ultrasonication for 45min.

[0056] Step 2: Coating: Use 3K two-dimensional plain carbon fiber cloth, apply a 50μm thick phenolic resin coating on the surface of the carbon cloth, put it in a 70℃ oven to dry (15min), apply a free silicon coating on the surface of the resin-coated carbon cloth to a thickness of 30μm, put it in a 70℃ oven to dry for 15min, and then apply a ceramic coating. After the ceramic layer reaches a thickness of 150μm, put it in a 70℃ oven to dry for 4h to obtain a coated carbon cloth. Repeat the above process to prepare 10 layers of carbon cloth with ceramic coating.

[0057] Step 3: Use PVA solution to bond the 10 layers of coated carbon cloth and stack them into a composite material blank. Place the blank in a vacuum drying oven for vacuum treatment and maintain the vacuum state for 15 minutes. After taking it out, place it in a 100°C oven for treatment for 1 hour to achieve the curing of the resin inside the composite material blank.

[0058] Step 4: Place the cured composite material body into a high-strength graphite mold, protect the mold with graphite paper, and keep the distance between the mold upper pressure head and the mold at 20 mm.

[0059] Step 5: Place the processed hot pressing mold into the hot pressing sintering furnace and sinter it under high vacuum (1-5×10 -4 The sample was heated at a rate of 10°C / min to 1800°C and held at that temperature for 60 minutes. During the heating process from room temperature to 1200°C, pressure was gradually applied until the sample pressure reached 30 MPa. After the holding time, the power was turned off and the sample was cooled, maintaining the pressure until the sample was removed. The hot pressing mold was removed after cooling to room temperature, yielding a SiC-modified C / C composite.

[0060] Example 2

[0061] A method for preparing a high-temperature ceramic-modified C / C composite material comprises the following steps:

[0062] Step 1: Prepare slurry: prepare resin slurry, free silicon slurry and ceramic particle slurry respectively. The specific method is: add 10g of phenolic resin particles to 100g of anhydrous ethanol solution, and obtain resin slurry after sufficient stirring (20min); add phenolic resin particles and Si powder to anhydrous ethanol solution in a molar ratio of 1:5, and stir evenly (30min) to obtain free silicon slurry; add ceramic powder and phenolic resin with HfB2, SiC, HfSi2, and Si in a molar ratio of 4:1:1:0.8 to anhydrous ethanol solution, and obtain ceramic particle slurry after sufficient stirring and ultrasonication for 45min.

[0063] Step 2: Coating: Use 3K two-dimensional plain carbon fiber cloth, apply a 50μm thick phenolic resin coating on the surface of the carbon cloth, put it in a 70℃ oven to dry (15min), apply a free silicon coating on the surface of the resin-coated carbon cloth to a thickness of 30μm, put it in a 70℃ oven to dry for 15min, and then apply a ceramic coating. After the ceramic layer reaches a thickness of 150μm, put it in a 70℃ oven to dry for 4h to obtain a coated carbon cloth. Repeat the above process to prepare 10 layers of carbon cloth with ceramic coating.

[0064] Step 3: Use PVA solution to bond the 10 layers of coated carbon cloth and stack them into a composite material blank. Place the blank in a vacuum drying oven for vacuum treatment and maintain the vacuum state for 15 minutes. After taking it out, place it in a 100°C oven for treatment for 1 hour to achieve the curing of the resin inside the composite material blank.

[0065] Step 4: Place the cured composite material body into a high-strength graphite mold, protect the mold with graphite paper, and keep the distance between the mold upper pressure head and the mold at 20 mm.

[0066] Step 5: Place the processed hot pressing mold into the hot pressing sintering furnace and sinter it under high vacuum (1-5×10 -4 The sample was heated at a rate of 10°C / min to 1800°C and held at that temperature for 60 minutes. During the heating process from room temperature to 1200°C, pressure was gradually applied until the sample pressure reached 30 MPa. After the holding time, the power was turned off and the sample was cooled, maintaining the pressure until the sample was removed. The hot pressing mold was removed after cooling to room temperature, yielding an HfB2-SiC modified C / C composite.

[0067] Example 3

[0068] A method for preparing a high-temperature ceramic-modified C / C composite material comprises the following steps:

[0069] Step 1: Prepare slurry: prepare resin slurry, free silicon slurry and ceramic particle slurry respectively. The specific method is: add 10g of phenolic resin particles to 100g of anhydrous ethanol solution, and obtain resin slurry after sufficient stirring (20min); add phenolic resin particles and Si powder to anhydrous ethanol solution in a molar ratio of 1:5, and stir evenly (30min) to obtain free silicon slurry; add ceramic powder and phenolic resin in a molar ratio of HfB2, SiC, HfSi2, and Si in a ratio of 4:1:1:0.8 to anhydrous ethanol solution, and obtain HfB2-SiC ceramic particle slurry after sufficient stirring and ultrasonication for 45min; add ceramic powder and phenolic resin in a molar ratio of SiC and Si in a ratio of 4:1 to anhydrous ethanol solution, and obtain SiC ceramic particle slurry after sufficient stirring and ultrasonication for 45min.

[0070] Step 2: Coating: Using 3K two-dimensional plain carbon fiber cloth, apply a 50μm thick phenolic resin coating to the surface of the carbon cloth. After drying in a 70°C oven for 15 minutes, apply a 30μm thick free silicon coating to the surface of the resin-coated carbon cloth. After drying in a 70°C oven for 15 minutes, five layers of the carbon cloth are coated with a hafnium-based ceramic coating, and the remaining five layers are coated with a SiC ceramic coating. After the ceramic layer reaches a thickness of 150μm, it is placed in a 70°C oven and dried for 4 hours to obtain a total of 10 layers of carbon cloth coated with the two coatings.

[0071] Step 3: Use PVA solution to bond and stack the 10 layers of coated carbon cloth in the order of "first stacking the hafnium-based coating on the carbon cloth, and then stacking the SiC ceramic coating on the carbon cloth" into a composite body, and place the body in a vacuum drying oven for vacuum treatment. Maintain the vacuum state for 15 minutes, take it out and place it in a 70°C oven for treatment for 1 hour to achieve the curing of the resin inside the composite body.

[0072] Step 4: Place the cured composite material body into a high-strength graphite mold, protect the mold with graphite paper, and keep the distance between the mold upper pressure head and the mold at 20 mm.

[0073] Step 5: Place the processed hot pressing mold into the hot pressing sintering furnace and sinter it under high vacuum (1-5×10 -4 The sample was heated at a rate of 10°C / min to 1800°C and held at that temperature for 60 minutes. During the heating process from room temperature to 1200°C, pressure was gradually applied until the sample pressure reached 30 MPa. After the holding time, the power was turned off and the sample was cooled, maintaining the pressure until the sample was removed. Once the hot pressing mold cooled to room temperature, it was removed, resulting in a carbon-based composite material synergistically modified with HfB2-SiC ceramic and SiC ceramic.

[0074] In order to illustrate the relevant properties of the high temperature ceramic modified C / C composite material prepared by the method provided by the present invention, see Figures 2-4 As shown,

[0075] Figure 2 This figure compares the room-temperature flexural properties of the HfB2-SiC modified C / C composite prepared by the RMI process and Example 2. The RMI process is a reactive infiltration process, in which ceramic is introduced into a carbon fiber braid at high temperature in the form of an infiltration liquid to obtain a ceramic-modified carbon-based composite. Figure 2 The specimens prepared by the RMI process showed brittle fracture in the bending test, while the specimens prepared by this process showed a pseudoplastic fracture mode in the test, which proves that this process can reduce the damage to carbon fiber.

[0076] Figure 3 The cross-sectional SEM photos and EDS analysis results of the HfB2-SiC modified C / C composite material prepared in Example 2. (a) is the cross-sectional morphology of the sample, (b) is the magnified view of (a), and (c) is the EDS spectrum analysis result. Figure 3 It can be seen that the ceramic layers are distributed relatively evenly, and the silicon transition layer (reacted to form a SiC layer) effectively improves the interface connection between the ceramic layer and the carbon cloth layer.

[0077] Figure 4The SEM photos of the HfB2-SiC ceramic and SiC ceramic co-modified C / C composite prepared in Example 3. (a) is the cross-sectional morphology of the sample, (b) is the magnified view of (a), and (c) is the EDS spectrum analysis result. Figure 4 It can be seen that the ceramic layers of different compositions are evenly coated on the surface of the carbon cloth layer with fewer cracks, and the ceramic layers of different compositions are tightly bonded, which shows that this process can achieve the advantages of multi-component design.

[0078] Figure 5 The ablation rate changes at each stage and the total ablation rate changes of the HfB2-SiC modified C / C composite material prepared in Example 2 before and after the introduction of the silicon transition layer at a flow rate of 2.38MW for 600s. a) is the linear ablation rate change of the two samples at each stage, (b) is the mass ablation rate change of the two samples at each stage, and (c) is the total ablation rate change of the two samples. Figure 5 It can be seen that the linear ablation rate and mass ablation rate of the sample decreased significantly after the introduction of the transition layer, and the sample had good anti-ablation performance under 600s ablation after the introduction of the transition layer.

[0079] The present invention describes preferred embodiments and their effects. However, those skilled in the art, once informed of the basic inventive concept, may make additional changes and modifications to these embodiments. Therefore, it is intended that the appended claims be interpreted to include the preferred embodiments as well as all changes and modifications that fall within the scope of the invention.

[0080] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an ultra-high temperature ceramic modified C / C composite material, characterized in that: The following steps are involved: Obtaining resin slurry, free silicon slurry and ceramic particle slurry; The resin slurry, the free silicon slurry and the ceramic particle slurry are sequentially applied to the surface of the carbon cloth to obtain a multi-layer coated carbon cloth; wherein each coated layer is dried; The carbon cloth coated with multiple layers of coating is stacked into a composite material body by using an adhesive, the body is vacuum treated, and then dried at 80-100° C. for 1-2 hours to obtain a cured composite material body; After the cured composite body is placed in a mold, the temperature is raised to 1700-1900°C at a rate of 10-15°C / min under vacuum and kept at this temperature for 30-60 minutes. At the same time, during the heating process from room temperature to 1200°C, pressure is gradually applied to the cured composite body until the sample pressure reaches 30-40 MPa. The pressure is maintained until the hot pressing mold cools to room temperature to obtain an ultrahigh temperature ceramic modified C / C composite material. The drying temperature for each coating layer is 60-80°C and the drying time is 10-15 minutes. After the ceramic particle slurry is coated, the drying time is 4-6 hours. The resin slurry is prepared by adding a certain amount of phenolic resin particles to an anhydrous ethanol solution and stirring; the free silicon slurry is prepared by adding phenolic resin particles and Si powder according to a certain molar ratio to an anhydrous ethanol solution and stirring; the ceramic particle slurry is prepared by adding ceramic powder, sintering aid and phenolic resin particles according to a certain molar ratio to an anhydrous ethanol solution and stirring; One or more ceramic particle slurries are coated on the surface of the carbon cloth, wherein the ceramic powder in each ceramic particle slurry is one or more of HfB2, ZrB2, HfSi2, SiC, and Si; After the resin slurry is applied to the surface of the carbon cloth, a resin layer with a thickness of 25 to 50 μm is formed on the surface of the carbon cloth after drying; the free silicon slurry is then applied to the resin layer, and a free silicon layer with a thickness of 15 to 30 μm is formed after drying; then the ceramic particle slurry is applied to the free silicon coating, and a ceramic layer with a thickness of 100 to 150 μm is formed after drying; thus, a carbon cloth coated with multiple layers of coating is obtained.

2. The method for preparing the ultrahigh temperature ceramic modified C / C composite material according to claim 1, characterized in that: The vacuum treatment is to place the green body into a vacuum drying oven for vacuum treatment, and maintain the vacuum state for 15 to 30 minutes.

3. The method for preparing the ultrahigh temperature ceramic modified C / C composite material according to claim 1, characterized in that: After the cured composite material body is placed in the mold, -4 The subsequent sintering is carried out in a vacuum environment of Pa, wherein the mold is a graphite mold.

4. The method for preparing the ultrahigh temperature ceramic modified C / C composite material according to claim 1, characterized in that: After the cured composite body is placed in the mold, the mold is protected with graphite paper around it and placed in a hot pressing sintering furnace, and the distance between the mold upper pressure head and the mold is maintained at 15~20 mm.

5. An ultra-high temperature ceramic modified C / C composite material prepared by the method according to any one of claims 1 to 4.

6. Use of the ultra-high temperature ceramic modified C / C composite material according to claim 5 in a hot end component of a hypersonic aircraft.

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