A graphene-toughened ceramic-based composite material and preparation method thereof

Abstract

The present invention relates to a graphene-toughened ceramic-based composite material and a preparation method thereof. The method comprises the following steps: alternately stacking carbon cloth and nickel foam sheets, and then using a puncture process to form a preform after the alternate stacking; depositing pyrolytic carbon and graphene in the preform by chemical vapor deposition, and then soaking the preform in an acid solution to obtain a porous carbon / carbon composite material with the nickel foam removed; using an oxygen-free hafnium carbide ceramic precursor as a reactant, depositing a hafnium carbide interface layer in the porous carbon / carbon composite material with the nickel foam removed by chemical vapor deposition to obtain a carbon / carbon composite material having a hafnium carbide interface layer; reacting the oxygen-free hafnium carbide ceramic precursor with the carbon / carbon composite material having a hafnium carbide interface layer by an impregnation cracking method to obtain a graphene-toughened ceramic-based composite material. The ceramic-based composite material prepared by the present invention has the advantages of high toughness and strong antioxidant properties, as shown by significantly improved mechanical properties in a high-temperature oxygen environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic-based composite material preparation, and in particular relates to a graphene-toughened ceramic-based composite material and a preparation method thereof. Background Art

[0002] Compared with traditional metals and carbon / carbon composites, carbon fiber-reinforced ceramic matrix composites have excellent properties such as light weight, high strength and high temperature resistance, and are the main candidate materials for many thermal structural components. In the composite material, it mainly includes four parts: carbon fiber, interface layer, ceramic matrix and coating. Among them, carbon fiber mainly plays the role of improving the toughness of the composite material, and the interface layer is the connecting link between the carbon fiber and the ceramic matrix. A moderate force is formed between the carbon fiber and the interface layer, which helps to strengthen the composite material and avoid brittle fracture. Due to the characteristics of carbon fiber bundles and easy weaving, the distribution of carbon fiber in the composite material is not uniform, which makes the ceramic matrix in this area more brittle and more likely to form through cracks. In addition, the conventional interface layer is mainly composed of pyrolytic carbon. Carbon fiber and pyrolytic carbon are both carbon materials, and the oxidation resistance of carbon materials is very poor, which can easily lead to damage to the structure and performance of carbon fiber. In order to meet the use requirements of ceramic matrix composites in extreme environments, it is urgent to improve the toughness, mechanical properties and / or oxidation resistance of ceramic matrix composites. Summary of the Invention

[0003] To address one or more technical problems existing in the prior art, the present invention provides a graphene-toughened ceramic-matrix composite material and a method for preparing the same. This invention addresses the issues of conventional carbon fiber-toughened ceramic-matrix composite materials, such as limited toughness and poor oxidation resistance, by improving the toughness and performance of the ceramic-matrix composite material in extreme thermal environments.

[0004] In a first aspect, the present invention provides a method for preparing a graphene-toughened ceramic-based composite material, the method comprising the following steps:

[0005] (1) Alternately laminating carbon cloth and nickel foam sheets, and then using a puncture process to form a preform;

[0006] (2) depositing pyrolytic carbon and graphene in the preform by chemical vapor deposition to obtain a porous carbon / carbon composite material;

[0007] (3) soaking the porous carbon / carbon composite material in an acid solution to obtain a porous carbon / carbon composite material from which the nickel foam is removed;

[0008] (4) using an oxygen-free hafnium carbide ceramic precursor as a reactant, depositing a hafnium carbide interface layer in the porous carbon / carbon composite material from which the nickel foam has been removed by chemical vapor deposition to obtain a carbon / carbon composite material having a hafnium carbide interface layer;

[0009] (5) The oxygen-free hafnium carbide ceramic precursor is reacted with the carbon / carbon composite material having the hafnium carbide interface layer by an impregnation pyrolysis method to obtain a graphene-toughened ceramic-based composite material.

[0010] Preferably, the thickness of the nickel foam sheet is 0.02-0.08 mm, and / or the surface density of the nickel foam sheet is 150-370 g / m 2 .

[0011] Preferably, the density of the preform is 0.8 to 1.2 g / cm 3 In the preform, the volume proportion of the nickel foam sheet is 5 to 20%; and / or in step (2), the density of the porous carbon / carbon composite material is 0.9 to 1.3 g / cm 3 .

[0012] Preferably, in step (2): the deposition is carried out in an atmosphere comprising nitrogen, hydrogen and methane, the volume flow ratio of the nitrogen, hydrogen and methane is 10:3:(2-5); and / or the deposition temperature is 800-1000°C, and the deposition time is 0.5-2h.

[0013] Preferably, in step (3): the acid solution is one or more of hydrochloric acid, nitric acid solution, and sulfuric acid solution; the concentration of the acid solution is not greater than 1 mol / L; and / or the soaking temperature is 25-50° C., and the soaking time is 2-5 h.

[0014] Preferably, in step (4): the oxygen-free hafnium carbide ceramic precursor is heated and then introduced into a chemical vapor deposition furnace through a carrier gas nitrogen, and hydrogen and methane are simultaneously introduced into the chemical vapor deposition furnace to deposit the hafnium carbide interface layer; wherein the volume flow ratio of nitrogen, hydrogen and methane is 10:6:(4~10).

[0015] Preferably, the heating temperature of the oxygen-free hafnium carbide ceramic precursor is 80-100° C.; the temperature for depositing the hafnium carbide interface layer is 1020-1550° C., the time is 0.5-2 h, and the pressure in the chemical vapor deposition furnace is 20-200 Pa.

[0016] Preferably, the thickness of the hafnium carbide interface layer is 0.5-1.5 μm; and / or the density of the graphene-toughened ceramic matrix composite material is 3.1-3.6 g / cm 3 .

[0017] Preferably, in step (4) and step (5), the preparation of the oxygen-free hafnium carbide ceramic precursor is as follows: tetrakis(dimethylamino)hafnium or tetrakis(diethylamino)hafnium is subjected to an amine exchange reaction with an amine compound, and then subjected to reduced pressure distillation to obtain the oxygen-free hafnium carbide ceramic precursor; the amine compound is one or more of di-n-propylamine, diisopropylamine, diallylamine, di-n-butylamine, diisobutylamine, di-n-pentylamine, tetrahydropyrrole, and hexahydropyridine.

[0018] In a second aspect, the present invention provides a graphene-toughened ceramic-based composite material prepared by the preparation method described in the first aspect of the present invention.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] (1) The present invention achieves uniform distribution of graphene in the ceramic matrix by laminating and weaving ultra-thin nickel foam sheets and carbon cloth, avoiding the problems of difficult dispersion and easy agglomeration in traditional graphene addition methods, and can significantly improve the toughness of ceramic-based composite materials.

[0021] (2) The present invention adopts chemical vapor deposition technology, uses oxygen-free hafnium carbide ceramic precursor as a reactant, and prepares an HfC interface layer on the carbon fiber pyrolytic carbon interface layer and the graphene surface. HfC itself has excellent antioxidant and ablation resistance. Compared with the traditional pyrolytic carbon single interface layer, it can improve the antioxidant performance of the composite material. In addition, the traditional method of forming the hafnium carbide interface layer requires a high-temperature carbon thermal reduction process because the hafnium carbide ceramic precursor used is an alkoxy structure and an aerobic system. The reaction temperature is generally not less than 1600°C, which will cause a certain degree of damage to the carbon fiber and thus have an adverse effect on the performance of the ceramic-based composite material. The present invention uses oxygen-free hafnium carbide ceramic precursor as a new type of hafnium-based ceramic precursor, which can realize the direct forming of hafnium carbide through chemical vapor deposition technology. At the same time, the chemical vapor deposition technology of the present invention can avoid the structural and performance damage caused by the corrosion of carbon fiber by the byproduct hydrogen chloride gas in the traditional process, effectively improving the antioxidant performance and high-temperature mechanical properties of the ceramic-based composite material.

[0022] (3) The graphene-toughened ceramic-based composite material prepared by the present invention has the advantages of high toughness and strong antioxidant performance, which is manifested in a significant improvement in mechanical properties in a high-temperature aerobic environment, thereby improving the performance of the ceramic-based composite material in an extreme thermal environment and solving the problems of low toughness and poor antioxidant performance commonly faced by ceramic-based composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a microstructure diagram (SEM diagram) of the graphene-toughened ceramic-based composite material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] In a first aspect, the present invention provides a method for preparing a graphene-toughened ceramic-based composite material, the method comprising the following steps:

[0026] (1) Alternately stacking carbon cloth and nickel foam sheets, and then using a puncture process to form a preform after the alternating stacking; in the present invention, the stacking is performed in the thickness direction, and a layer of nickel foam sheet is provided between every two layers of carbon cloth. After the alternating stacking, the preform is woven into a puncture preform by a puncture process; the nickel foam sheet is thin and has a high porosity, and can be used to prepare a preform with the carbon cloth by the puncture process; in the present invention, the nickel foam sheet can be ultrasonically cleaned 1-3 times with ethanol or acetone before use to remove impurities on the surface; the present invention does not specifically limit the conditions of the puncture process, and a conventional puncture process in the art can be used; in the present invention, the carbon cloth is woven from carbon fibers;

[0027] (2) depositing pyrolytic carbon and graphene in (inside) the preform by chemical vapor deposition to obtain a porous carbon / carbon composite material;

[0028] (3) soaking the porous carbon / carbon composite material in an acid solution to remove the nickel foam, thereby obtaining a porous carbon / carbon composite material from which the nickel foam has been removed;

[0029] (4) using an oxygen-free hafnium carbide ceramic precursor (also referred to as a polymer oxygen-free hafnium carbide ceramic precursor) as a reactant, depositing a hafnium carbide interface layer in the porous carbon / carbon composite material from which the nickel foam has been removed by chemical vapor deposition, thereby obtaining a carbon / carbon composite material having a hafnium carbide interface layer; specifically, for example, placing the porous carbon / carbon composite material from which the nickel foam has been removed in a chemical vapor deposition furnace, and introducing nitrogen, hydrogen, and methane into the composite material under vacuum and high temperature conditions by controlling the heating temperature of the polymer oxygen-free hafnium carbide ceramic precursor, thereby forming a hafnium carbide interface layer on the surfaces of the continuous carbon fiber and the graphene after a certain period of time;

[0030] (5) reacting an oxygen-free hafnium carbide ceramic precursor with the carbon / carbon composite material having a hafnium carbide interface layer by an impregnation pyrolysis method to obtain a graphene-toughened ceramic-based composite material; in the present invention, the oxygen-free hafnium carbide ceramic precursor does not contain oxygen; in the present invention, when reacting the oxygen-free hafnium carbide ceramic precursor with the carbon / carbon composite material having a hafnium carbide interface layer by an impregnation pyrolysis method (impregnation / curing / pyrolysis PIP process), the liquid oxygen-free hafnium carbide ceramic precursor is filled in the pores of the carbon / carbon composite material, and finally a graphene-toughened ceramic-based composite material is formed through a curing pyrolysis process; in the present invention, preferably, the The impregnation is first performed by vacuum impregnation, the pressure of vacuum impregnation is, for example, 20 to 200 Pa, and then pressure impregnation is performed, the pressure of pressure impregnation is 2 to 3 MPa, the time of each vacuum impregnation is 1 to 2 hours, the time of each pressure impregnation is 1 to 2 hours, the temperature of the curing is 250 to 400 ° C, the time of each curing is 2 to 4 hours, the curing is carried out in an argon atmosphere, the temperature of the cracking is 1400 to 1600 ° C, the time of each cracking is 2 to 4 hours, and the cracking is carried out in an argon atmosphere. The present invention does not specifically limit the number of times the impregnation, curing and cracking are repeated until the density of the material reaches 3.1 to 3.6 g / cm 3 In the present invention, the pressures involved refer to absolute pressures.

[0031] The present invention uses nickel foam as a substrate and weaves it with carbon cloth to form a preform. The graphene is evenly distributed inside the ceramic matrix by chemical vapor deposition technology, avoiding the problems of difficult dispersion and easy agglomeration in traditional graphene addition methods. It can greatly improve the toughness of ceramic-based composite materials. At the same time, the hafnium carbide interface layer can significantly improve the oxidation resistance of ceramic-based composite materials, solving the problems of low toughness and poor oxidation resistance commonly faced by ceramic-based composite materials.

[0032] The present invention adopts chemical vapor deposition technology, uses oxygen-free hafnium carbide ceramic precursor as a reactant, and prepares an HfC interface layer on the carbon fiber pyrolytic carbon interface layer and the graphene surface. HfC itself has excellent antioxidant and ablation resistance. Compared with the traditional pyrolytic carbon single interface layer, it can improve the antioxidant performance of the composite material. In addition, the traditional method of forming the hafnium carbide interface layer requires a carbon thermal reduction process due to the alkoxy structure of the hafnium carbide ceramic precursor used. The reaction temperature is generally not less than 1600°C, which will cause a certain degree of damage to the carbon fiber and thus have an adverse effect on the performance of the ceramic-based composite material. The present invention adopts oxygen-free hafnium carbide ceramic precursor as a new type of hafnium-based ceramic precursor, which can achieve direct forming of hafnium carbide. At the same time, through the chemical vapor deposition technology of the present invention, it can avoid the structural and performance damage caused by the corrosion of carbon fiber by the byproduct hydrogen chloride gas in the traditional process, effectively improving the antioxidant performance and high-temperature mechanical properties of the ceramic-based composite material.

[0033] According to some preferred embodiments, the thickness of the nickel foam sheet is 0.02 to 0.08 mm (e.g., 0.02, 0.03, 0.04, 0.05, 0.06, 0.07 or 0.08 mm), and / or the surface density of the nickel foam sheet is 150 to 370 g / m 2 (e.g. 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360 or 370 g / m 2 ); In the present invention, the thickness of the nickel foam sheet is preferably 0.02 to 0.08 mm. The present invention finds that controlling the thickness of the nickel foam sheet is very critical. If the thickness is higher than 0.08 mm, the pores will be too large after the acid solution is removed, affecting the mechanical properties of the composite material; and if the thickness is lower than 0.02 mm, the subsequent graphene content will be low, and the composite material cannot be toughened well; In the present invention, the thickness of the nickel foam sheet is 0.02 to 0.08 mm, which can also be recorded as an ultra-thin nickel foam sheet.

[0034] According to some preferred embodiments, the density of the preform is 0.8 to 1.2 g / cm 3 (e.g. 0.8, 0.9, 1.0, 1.1 or 1.2 g / cm 3 ); in the preform, the volume proportion of the nickel foam sheet is 5-20% (for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%), in other words, in the preform, the volume proportion of the nickel foam sheet is 5%-20%; the present invention does not specifically limit the number of layers of alternating carbon cloth and nickel foam sheet, so that in the preform, the volume proportion of the nickel foam sheet is 5-20%; and / or in step (2), the density of the porous carbon / carbon composite material is 0.9-1.3 g / cm 3 (e.g. 0.9, 1.0, 1.1, 1.2 or 1.3 g / cm 3 In the present invention, the volume proportion of the nickel foam sheet in the preform is preferably 5 to 20%. The present invention has found that by controlling the volume proportion of the nickel foam sheet, the mechanical properties of the ceramic-based composite material can be effectively regulated. When the volume proportion of the nickel foam sheet is higher than 20%, the pores will be too large after the acid solution is removed, affecting the mechanical properties of the composite material. When the volume proportion of the nickel foam sheet is lower than 5%, the subsequent graphene content is low, and the composite material cannot be well toughened.

[0035] According to some preferred embodiments, in step (2): the deposition is carried out in an atmosphere comprising nitrogen, hydrogen and methane, and the volume flow ratio of the nitrogen, hydrogen and methane is 10:3:(2-5) (for example, 10:3:2, 10:3:2.5, 10:3:3, 10:3:3.5, 10:3:4, 10:3:4.5 or 10:3:5); and / or the deposition temperature is 800-1000°C (for example, 800°C, 850°C, 900°C, 950°C or 1000°C), and the deposition time is 0.5-2h (for example, 0.5, 1, 1.5 or 2h).

[0036] The present invention has found that when depositing pyrolytic carbon and graphene inside the preform, the key is to control the flow ratio of nitrogen, hydrogen, and methane, that is, in step (2), the deposition is carried out, and preferably the volume flow ratio of nitrogen, hydrogen, and methane is 10:3:(2-5), which is conducive to ensuring that the ceramic matrix composite material with high toughness and strong oxidation resistance is obtained, and the mechanical properties of the obtained ceramic matrix composite material in a high-temperature oxygen environment are significantly improved. Although there are reports on growing a pyrolytic carbon interface layer on the surface of carbon fiber or growing graphene on the surface of nickel foam, it is relatively difficult to achieve uniform preparation of pyrolytic carbon and graphene in the same cavity and the same sample, and no prior art has been found to involve this. This is because the deposition of methane on the surface of carbon fiber is a non-catalytic growth, while the deposition on the surface of nickel foam is a metal-catalyzed growth, and the growth mechanisms of the two are quite different. The present invention creatively achieves good pyrolytic carbon and graphene growth effects simultaneously by finely regulating the flow ratio of nitrogen, hydrogen and methane at 10:3:(2-5); the present invention finds that if the flow ratio of the three is lower than 10:3:2, graphene growth on the surface of nickel foam will be good while the deposition effect of pyrolytic carbon on the surface of carbon fiber will be poor; if the flow ratio of the three is higher than 10:3:5, amorphous carbon rather than graphene will be more easily formed on the surface of nickel foam.

[0037] According to some specific embodiments, step (2) is: placing the preform obtained in step (1) in a high-temperature furnace cavity (also referred to as a chemical vapor deposition reactor cavity or a chemical vapor deposition furnace cavity), evacuating the cavity to 20-200 Pa, removing the air in the cavity, and then continuously filling the cavity with nitrogen and hydrogen, and heating the temperature at a rate of 1-8°C / min to a reaction temperature of 800-1000°C. At this time, methane is introduced, and the flow ratio of nitrogen, hydrogen and methane is controlled at 10:3:2-5. The reaction time is 0.5-2h. After the reaction is completed, heating is stopped, and nitrogen is continued to be introduced until the cavity temperature drops to room temperature, and the sample is taken out to obtain a porous carbon / carbon composite material; in the present invention, the room temperature is, for example, room temperature 15-35°C.

[0038] According to some preferred embodiments, in step (3): the acid solution is one or more of hydrochloric acid, nitric acid solution, and sulfuric acid solution; the concentration of the acid solution is not greater than 1 mol / L; and / or the soaking temperature is 25 to 50°C (for example, 25°C, 30°C, 35°C, 40°C, 45°C, or 50°C), and the soaking time is 2 to 5h (for example, 2, 3, 4, or 5h).

[0039] According to some specific embodiments, step (3) is: soaking the porous carbon / carbon composite material obtained in step (2) in any one of hydrochloric acid, dilute nitric acid or dilute sulfuric acid, and then placing it in distilled water, and repeating the process multiple times to ensure complete removal of the nickel foam.

[0040] According to some preferred embodiments, in step (4): the oxygen-free hafnium carbide ceramic precursor is heated and then introduced into a chemical vapor deposition furnace through a carrier gas nitrogen, and hydrogen and methane are simultaneously introduced into the chemical vapor deposition furnace to deposit the hafnium carbide interface layer; wherein the volume flow ratio of nitrogen, hydrogen and methane is 10:6:(4-10) (for example, 10:6:4, 10:6:5, 10:6:6, 10:6:7, 10:6:8, 10:6:9 or 10:6:10).

[0041] According to some preferred embodiments, the heating temperature of the oxygen-free hafnium carbide ceramic precursor is 80-100°C (e.g., 80°C, 90°C, or 100°C); the temperature for depositing the hafnium carbide interface layer is 1020-1550°C (e.g., 1020°C, 1050°C, 1080°C, 1100°C, 1120°C, 1150°C, 1180°C, 1200°C, 1250°C, 1300°C, 1350°C, 0°C, 1400°C, 1450°C, 1500°C or 1550°C), the time is 0.5-2h (for example, 0.5, 1, 1.5 or 2h), the pressure in the chemical vapor deposition furnace is 20-200Pa (for example, 20, 50, 80, 100, 120, 150, 180 or 200Pa); in some preferred embodiments, the temperature for depositing the hafnium carbide interface layer is 1020-1180°C.

[0042] The present invention has found through a large number of creative experiments that, when a hafnium carbide ceramic precursor is used as a reactant and a hafnium carbide interface layer is deposited in the porous carbon / carbon composite material from which nickel foam is removed by chemical vapor deposition, it is preferred to control the chemical vapor deposition temperature in the reactor to be 1020-1550°C and to adjust the flow ratio of nitrogen, hydrogen and methane to be 10:6:(4-10), so as to ensure that a ceramic matrix composite material with strong antioxidant properties and significantly improved mechanical properties in a high-temperature oxygen environment is obtained; the present invention has found that if the chemical vapor deposition temperature is too high, the oxygen-free hafnium carbide ceramic precursor will be affected. If the thermal decomposition rate is too fast, amorphous carbon and other substances may be formed, resulting in a decrease in the oxidation resistance of the ceramic-based composite material. If the chemical vapor deposition temperature is lower than 1020°C, the oxygen-free hafnium carbide ceramic precursor will not be fully cracked, and a stable HfC interface layer will not be formed, which will also lead to a decrease in the oxidation resistance of the ceramic-based composite material. If the flow ratio of nitrogen, hydrogen and methane is higher than 10:6:10, excessive methane will more easily form amorphous carbon, resulting in a decrease in the oxidation resistance of the material. If it is lower than 10:6:4, the methane supply is insufficient, which can easily lead to poor HfC crystal shape, also affecting its oxidation resistance.

[0043] According to some preferred embodiments, the thickness of the hafnium carbide interface layer is 0.5-1.5 μm (eg, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4 or 1.5 μm).

[0044] According to some specific embodiments, step (4) is: placing the porous carbon / carbon composite material from which the nickel foam has been removed in a chemical vapor deposition furnace, drawing a vacuum, and maintaining the pressure in the reaction furnace at 20-200 Pa. At the same time, the temperature in the reaction furnace is controlled at 1020-1550° C., and the temperature is maintained for 10 minutes to ensure that the temperature inside the furnace reaches a uniform state. Next, the heated oxygen-free hafnium carbide ceramic precursor is brought into the chemical vapor deposition furnace cavity by nitrogen as a carrier gas. The heating temperature of the oxygen-free hafnium carbide ceramic precursor is controlled at 80-100° C. While maintaining the carrier gas continuously carrying the oxygen-free hafnium carbide ceramic precursor into the cavity, hydrogen and methane are also introduced into the chemical vapor deposition furnace cavity (furnace cavity), and the volume flow ratio of the carrier gas nitrogen, hydrogen and methane is controlled to be 10:6:4-10, wherein the nitrogen flow rate is controlled at 1-3 L / min. After the reactor is kept warm for 0.5-2 hours, a hafnium carbide interface layer with a thickness of 0.5-1.5 μm forms on the carbon fiber (continuous carbon fiber) and graphene surfaces. The temperature is then lowered, and heating of the oxygen-free hafnium carbide ceramic precursor, as well as the introduction of methane and hydrogen, is stopped. Nitrogen is maintained throughout the cooling process until the temperature reaches room temperature, at which point the sample is removed.

[0045] According to some preferred embodiments, the density of the graphene-toughened ceramic-based composite material is 3.1 to 3.6 g / cm3 The present invention uses oxygen-free hafnium carbide ceramic precursor as a reactant and prepares a graphene-toughened ceramic matrix composite material by precursor impregnation and cracking, preferably with a density of 3.1 to 3.6 g / cm 3 The graphene-toughened ceramic-based composite material prepared by the present invention has the advantages of high toughness and strong oxidation resistance, and is manifested in significantly improved mechanical properties in a high-temperature oxygen environment.

[0046] According to some preferred embodiments, in step (4) and step (5), the preparation of the oxygen-free hafnium carbide ceramic precursor is as follows: tetrakis(dimethylamino)hafnium or tetrakis(diethylamino)hafnium is subjected to an amine exchange reaction with an amine compound, and the reaction is carried out under reduced pressure distillation to obtain the oxygen-free hafnium carbide ceramic precursor; in the present invention, the amine compound undergoes an amine exchange reaction with tetrakis(dimethylamino)hafnium or tetrakis(diethylamino)hafnium, and the by-product is low-boiling dimethylamine or diethylamine. After the low-boiling by-product is removed by reduced pressure distillation, the oxygen-free hafnium carbide ceramic precursor can be obtained, and the amine exchange reaction is carried out in an inert gas atmosphere, for example, in an argon atmosphere; the amine compound is subjected to an amine exchange reaction with tetrakis(dimethylamino)hafnium or tetrakis(diethylamino)hafnium. The compound is selected from one or more of di-n-propylamine, diisopropylamine, diallylamine (diallylamine), di-n-butylamine, diisobutylamine, di-n-pentylamine, tetrahydropyrrole, and hexahydropyridine; the molar ratio of tetrakis(dimethylamino)hafnium or tetrakis(diethylamino)hafnium to the amine compound is 1:(1-4); the temperature of the amine exchange reaction is 20°C-30°C, and the time is 12-18 hours; the present invention uses amino groups as ligands to stabilize the metal center, so that the prepared oxygen-free hafnium carbide ceramic precursor does not contain oxygen, which is beneficial to reducing the residual oxygen content of the pyrolysis product and improving the performance of the ceramic-based composite material, and the obtained oxygen-free hafnium carbide ceramic precursor is liquid.

[0047] In a second aspect, the present invention provides a graphene-toughened ceramic-based composite material prepared by the preparation method described in the first aspect of the present invention.

[0048] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments. The present invention may also have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention. Unless otherwise specified, the experimental methods used in the following examples are all conventional methods. The materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels or prepared by existing methods.

[0049] The preparation of the oxygen-free hafnium carbide ceramic precursor involved in the following embodiments and comparative examples of the present invention is as follows:

[0050] The three-necked flask was repeatedly evacuated and filled with argon to replace the air, and tetrakis(diethylamino)hafnium was added, followed by diallylamine. The mixture was stirred and reacted at 30°C in an argon atmosphere for 18 hours. The reactants were then distilled under reduced pressure to remove low-boiling point substances, thereby obtaining a liquid oxygen-free hafnium carbide ceramic precursor. The molar ratio of tetrakis(diethylamino)hafnium to diallylamine was 1:1.

[0051] Example 1

[0052] ① Nickel foam sheet: The thickness of the ultra-thin nickel foam sheet is 0.05mm and the surface density is 350g / m 2 , ultrasonically cleaned with ethanol twice to remove surface impurities.

[0053] ② Preform weaving: The nickel foam sheet and carbon cloth are stacked and arranged, and the preform is weaved into a preform by a puncture process, so that the volume ratio of the nickel foam sheet is 12%; the density of the obtained preform is 1.05g / cm 3 .

[0054] ③ Preparation of porous carbon / carbon composite materials: Place the above-mentioned preform in the cavity of a chemical vapor deposition furnace, evacuate to 80 Pa, remove the air in the cavity, and then continuously fill the cavity with nitrogen and hydrogen. The temperature is raised to a reaction temperature of 1000°C at a heating rate of 6°C / min. At this time, methane is introduced. The volume flow ratio of nitrogen, hydrogen and methane is controlled at 10:3:4. The reaction time is 1 hour. After the reaction is completed, stop heating and continue to introduce nitrogen until the cavity temperature drops to room temperature. Take out the sample to obtain a porous carbon / carbon composite material.

[0055] ④ Removal of nickel foam: Soak the above-mentioned porous carbon / carbon composite material in 0.5 mol / L hydrochloric acid solution at 50°C for 3 hours, then place it in distilled water for washing, repeat the hydrochloric acid solution soaking and distilled water washing several times in sequence to ensure complete removal of nickel foam, and dry it to obtain a porous carbon / carbon composite material with nickel foam removed.

[0056] ⑤ Preparation of HfC interface layer: The porous carbon / carbon composite material with nickel foam removed is placed in a chemical vapor deposition reactor, vacuum is drawn, the pressure in the reactor is 150Pa, and the temperature in the reactor is controlled at 1075℃ and kept warm for 10 minutes to ensure that the temperature inside the furnace reaches a uniform state. Next, the heated oxygen-free hafnium carbide ceramic precursor is brought into the chemical vapor deposition reactor chamber by nitrogen as a carrier gas. The heating temperature of the oxygen-free hafnium carbide ceramic precursor is controlled at 90℃. While the carrier gas nitrogen continues to carry the oxygen-free hafnium carbide ceramic precursor into the chamber, hydrogen and methane are introduced into the furnace chamber. The volume flow ratio of nitrogen, hydrogen and methane is 10:6:5, of which the nitrogen flow rate is controlled at 2L / min. After the reactor is kept at 1075℃ for 1 hour, a hafnium carbide interface layer (HfC interface layer) with a thickness of 1.0μm is formed on the surface of the carbon fiber and graphene. The temperature is then lowered, and heating of the oxygen-free hafnium carbide ceramic precursor and introduction of methane and hydrogen are stopped in sequence. Nitrogen is introduced throughout the entire cooling process until the temperature drops to room temperature. The sample is taken out to obtain a carbon / carbon composite material with a hafnium carbide interface layer.

[0057] ⑥ Preparation of graphene-toughened ceramic matrix composites: Using oxygen-free hafnium carbide ceramic precursor as a reactant, the oxygen-free hafnium carbide ceramic precursor was reacted with a carbon / carbon composite material having a hafnium carbide interface layer by an impregnation / curing / cracking process to prepare a graphene-toughened ceramic matrix composite with a density of 3.3 g / cm 3 Graphene-toughened ceramic-based composite materials; in each impregnation / curing / cracking round, the impregnation is first performed by vacuum impregnation, the vacuum impregnation pressure is 200Pa, and then pressure impregnation is performed, the pressure of pressure impregnation is 2MPa, the time of each vacuum impregnation is 1.5h, the time of each pressure impregnation is 1.5h, the temperature of the curing is 280°C, the time of each curing is 3h, the curing is carried out in an argon atmosphere, the temperature of the cracking is 1500°C, the time of each cracking is 3h, and the cracking is carried out in an argon atmosphere.

[0058] Mechanical property test under high temperature oxygen environment: The graphene-toughened ceramic-based composite material prepared in this embodiment was measured to have a flexural strength of 342 MPa under 1500°C air environment.

[0059] Example 2

[0060] ① Nickel foam sheet: The thickness of the ultra-thin nickel foam sheet is 0.08mm and the surface density is 350g / m 2 , ultrasonically cleaned with ethanol twice to remove surface impurities.

[0061] ② Preform weaving: The nickel foam sheet and carbon cloth are stacked and arranged, and the preform is weaved into a preform by a puncture process, so that the volume ratio of the nickel foam sheet is 18%; the density of the obtained preform is 1.15g / cm3 .

[0062] ③ Preparation of porous carbon / carbon composite materials: Place the above-mentioned preform in the cavity of a chemical vapor deposition furnace, evacuate to 80 Pa, remove the air in the cavity, and then continuously fill the cavity with nitrogen and hydrogen. The temperature is raised to a reaction temperature of 1000°C at a heating rate of 6°C / min. At this time, methane is introduced. The volume flow ratio of nitrogen, hydrogen and methane is controlled at 10:3:4. The reaction time is 1 hour. After the reaction is completed, stop heating and continue to introduce nitrogen until the cavity temperature drops to room temperature. Take out the sample to obtain a porous carbon / carbon composite material.

[0063] ④ Removal of nickel foam: Soak the above-mentioned porous carbon / carbon composite material in 0.5 mol / L hydrochloric acid solution at 50°C for 3 hours, then place it in distilled water for washing, repeat the hydrochloric acid solution soaking and distilled water washing several times in sequence to ensure complete removal of nickel foam, and dry it to obtain a porous carbon / carbon composite material with nickel foam removed.

[0064] ⑤ Preparation of HfC interface layer: The porous carbon / carbon composite material with nickel foam removed is placed in a chemical vapor deposition reactor, vacuum is drawn, the pressure in the reactor is 150Pa, and the temperature in the reactor is controlled at 1075℃ and kept warm for 10 minutes to ensure that the temperature inside the furnace reaches a uniform state. Next, the heated oxygen-free hafnium carbide ceramic precursor is brought into the chemical vapor deposition reactor chamber by nitrogen as a carrier gas. The heating temperature of the oxygen-free hafnium carbide ceramic precursor is controlled at 90℃. While maintaining the carrier gas continuously carrying the oxygen-free hafnium carbide ceramic precursor into the chamber, hydrogen and methane are introduced into the furnace chamber. The volume flow ratio of nitrogen, hydrogen and methane is 10:6:5, of which the nitrogen flow rate is controlled at 2L / min. After the reactor is kept at 1075℃ for 1 hour, a hafnium carbide interface layer (HfC interface layer) with a thickness of 1.0μm is formed on the surface of the carbon fiber and graphene. The temperature is then lowered, and heating of the oxygen-free hafnium carbide ceramic precursor and introduction of methane and hydrogen are stopped in sequence. Nitrogen is introduced throughout the entire cooling process until the temperature drops to room temperature. The sample is taken out to obtain a carbon / carbon composite material with a hafnium carbide interface layer.

[0065] ⑥ Preparation of graphene-toughened ceramic matrix composites: Using oxygen-free hafnium carbide ceramic precursor as a reactant, the oxygen-free hafnium carbide ceramic precursor was reacted with a carbon / carbon composite material having a hafnium carbide interface layer by an impregnation / curing / cracking process to prepare a graphene-toughened ceramic matrix composite with a density of 3.5 g / cm 3Graphene-toughened ceramic-based composite materials; in each impregnation / curing / cracking round, the impregnation is first performed by vacuum impregnation, the vacuum impregnation pressure is 200Pa, and then pressure impregnation is performed, the pressure of pressure impregnation is 2MPa, the time of each vacuum impregnation is 1.5h, the time of each pressure impregnation is 1.5h, the temperature of the curing is 280°C, the time of each curing is 3h, the curing is carried out in an argon atmosphere, the temperature of the cracking is 1500°C, the time of each cracking is 3h, and the cracking is carried out in an argon atmosphere.

[0066] Mechanical property test under high temperature oxygen environment: The graphene-toughened ceramic-based composite material prepared in this embodiment was measured to have a flexural strength of 371 MPa under 1500°C air environment.

[0067] Example 3

[0068] ① Nickel foam sheet: The thickness of the ultra-thin nickel foam sheet is 0.05mm and the surface density is 350g / m 2 , ultrasonically cleaned with ethanol twice to remove surface impurities.

[0069] ② Preform weaving: The nickel foam sheet and carbon cloth are stacked and arranged, and the preform is weaved into a preform by a puncture process, so that the volume ratio of the nickel foam sheet is 12%; the density of the obtained preform is 1.05g / cm 3 .

[0070] ③ Preparation of porous carbon / carbon composite materials: Place the above-mentioned preform in the cavity of a chemical vapor deposition furnace, evacuate to 80 Pa, remove the air in the cavity, and then continuously fill the cavity with nitrogen and hydrogen. The temperature is raised to a reaction temperature of 1000°C at a heating rate of 6°C / min. At this time, methane is introduced. The volume flow ratio of nitrogen, hydrogen and methane is controlled at 10:3:4. The reaction time is 1 hour. After the reaction is completed, stop heating and continue to introduce nitrogen until the cavity temperature drops to room temperature. Take out the sample to obtain a porous carbon / carbon composite material.

[0071] ④ Removal of nickel foam: Soak the above-mentioned porous carbon / carbon composite material in 0.5 mol / L hydrochloric acid solution at 50°C for 3 hours, then place it in distilled water for washing, repeat the hydrochloric acid solution soaking and distilled water washing several times in sequence to ensure complete removal of nickel foam, and dry it to obtain a porous carbon / carbon composite material with nickel foam removed.

[0072] ⑤ Preparation of HfC interface layer: The porous carbon / carbon composite material with the nickel foam removed is placed in a chemical vapor deposition reactor, vacuumed, and the pressure in the reactor is 150Pa. At the same time, the temperature in the reactor is controlled at 1075℃ and kept warm for 10 minutes to ensure that the temperature inside the furnace reaches a uniform state. Next, the heated oxygen-free hafnium carbide ceramic precursor is brought into the chemical vapor deposition reactor chamber by nitrogen as a carrier gas. The heating temperature of the oxygen-free hafnium carbide ceramic precursor is controlled at 90℃. While the carrier gas nitrogen continues to carry the oxygen-free hafnium carbide ceramic precursor into the chamber, hydrogen and methane are introduced into the furnace chamber. The volume flow ratio of nitrogen, hydrogen and methane is 10:6:5, of which the nitrogen flow rate is controlled at 2L / min. After the reactor is kept at 1075℃ for 2 hours, a hafnium carbide interface layer (HfC interface layer) with a thickness of 1.5μm is formed on the surface of the carbon fiber and graphene. The temperature is then lowered, and heating of the oxygen-free hafnium carbide ceramic precursor and introduction of methane and hydrogen are stopped in sequence. Nitrogen is introduced throughout the entire cooling process until the temperature drops to room temperature. The sample is taken out to obtain a carbon / carbon composite material with a hafnium carbide interface layer.

[0073] ⑥ Preparation of graphene-toughened ceramic matrix composites: Using oxygen-free hafnium carbide ceramic precursor as a reactant, the oxygen-free hafnium carbide ceramic precursor was reacted with a carbon / carbon composite material having a hafnium carbide interface layer by an impregnation / curing / cracking process to prepare a graphene-toughened ceramic matrix composite with a density of 3.4 g / cm 3 Graphene-toughened ceramic-based composite materials; in each impregnation / curing / cracking round, the impregnation is first performed by vacuum impregnation, the vacuum impregnation pressure is 200Pa, and then pressure impregnation is performed, the pressure of pressure impregnation is 2MPa, the time of each vacuum impregnation is 1.5h, the time of each pressure impregnation is 1.5h, the temperature of the curing is 280°C, the time of each curing is 3h, the curing is carried out in an argon atmosphere, the temperature of the cracking is 1500°C, the time of each cracking is 3h, and the cracking is carried out in an argon atmosphere.

[0074] Mechanical property test under high temperature oxygen environment: The graphene-toughened ceramic-based composite material prepared in this embodiment was measured to have a flexural strength of 386 MPa under 1500°C air environment.

[0075] As can be seen from the above Examples 1 to 3, compared to Example 1, when selecting the nickel foam sheet in Example 2, the thickness of the nickel foam sheet is increased from 0.05mm to 0.08mm, so that the volume proportion of the nickel foam in the preform is increased from 12% to 18%, thereby increasing the volume proportion of graphene that can be grown, and the mechanical properties of the final ceramic matrix composite are significantly improved, and the flexural strength in an air environment of 1500°C is increased from 342MPa to 371MPa. Compared to Example 1, when preparing the HfC interface layer in Example 3, the thickness of the HfC interface layer is increased from 1.0μm to 1.5μm, effectively improving the ability to protect carbon fiber and graphene, which significantly improves the antioxidant properties of the final ceramic matrix composite, and the flexural strength in an air environment of 1500°C is increased from 342MPa to 386MPa.

[0076] Examples 4 to 11

[0077] The specific process parameters of Examples 4 to 11 and the performance indicators of the finally prepared ceramic matrix composite materials are shown in Table 1. The other preparation processes are the same as those of Example 1.

[0078]

[0079] As can be seen from Table 1, compared with Example 1, when the nickel foam sheet is selected in Example 4, the thickness of the nickel foam sheet is reduced from 0.05mm to 0.01mm, so that the volume ratio of the nickel foam in the preform is reduced from 12% to 2%, resulting in a lower volume ratio of graphene that can be grown, and the resulting ceramic matrix composite material has low mechanical properties, with the flexural strength in an air environment of 1500°C reduced from 342MPa to 269MPa. Compared with Example 1, when the nickel foam sheet is selected in Example 5, the thickness of the nickel foam sheet is increased from 0.05mm to 0.1mm, so that the volume ratio of the nickel foam in the preform is increased from 12% to 24%, which will result in too large pores after the acid solution is removed, significantly affecting the mechanical properties of the ceramic matrix composite material, and the flexural strength in an air environment of 1500°C is reduced from 342MPa to 193MPa. Compared to Example 1, when selecting the deposition temperature of the oxygen-free hafnium carbide ceramic precursor in Example 6, the deposition temperature was lowered from 1075°C to 950°C, resulting in insufficient precursor decomposition and poor HfC deposition. The resulting ceramic-based composite material had poor oxidation resistance, with the flexural strength at 1500°C in air decreasing from 342 MPa to 216 MPa. Compared to Example 1, when selecting the deposition temperature of the oxygen-free hafnium carbide ceramic precursor in Example 7, the deposition temperature was increased from 1075°C to 1700°C. The thermal decomposition rate was too rapid, potentially forming substances such as amorphous carbon, which reduced the material's oxidation resistance. The flexural strength at 1500°C in air decreased from 342 MPa to 237 MPa. Compared to Example 1, in Example 8, when depositing pyrolytic carbon and graphene, the flow ratio of nitrogen, hydrogen, and methane was reduced from 10:3:4 to 10:3:1, resulting in good graphene growth on the nickel foam surface and poor deposition of pyrolytic carbon on the carbon fiber surface, which also significantly affected the mechanical properties of the composite material. The flexural strength in an air environment of 1500°C was reduced from 342MPa to 284MPa. Compared to Example 1, in Example 9, when depositing pyrolytic carbon and graphene, the flow ratio of nitrogen, hydrogen, and methane was increased from 10:3:4 to 10:3:8, resulting in amorphous carbon being more easily formed on the surface of the nickel foam rather than graphene. The flexural strength in an air environment of 1500°C was reduced from 342MPa to 220MPa. Compared to Example 1, in Example 10, when depositing the HfC interface layer, the flow ratio of nitrogen, hydrogen, and methane was reduced from 10:6:5 to 10:6:2. Insufficient methane supply easily leads to poor HfC crystallinity, affecting the oxidation resistance of the ceramic matrix composite material. The flexural strength in an air environment at 1500°C decreased from 342 MPa to 231 MPa. Compared to Example 1, in Example 11, when depositing the HfC interface layer, the flow ratio of nitrogen, hydrogen, and methane was increased from 10:6:5 to 10:6:12. Excessive methane more easily forms amorphous carbon, which also leads to poor oxidation resistance of the ceramic matrix composite material. The flexural strength in an air environment at 1500°C decreased from 342 MPa to 201 MPa.

[0080] Comparative Example 1

[0081] ① providing continuous carbon fibers (polyacrylonitrile-based carbon fibers) with an average diameter of 7 μm; preparing a single-layer graphene oxide (the average size of the single-layer graphene oxide is 2 μm) into a graphene oxide solution with a concentration of 0.1 mg / mL using acetone and water in a volume ratio of 1:1; uniformly spraying the graphene oxide solution on the surface of the continuous carbon fibers, placing the sprayed carbon fibers in a 0°C drying oven for low-temperature treatment for 600 minutes, slowly evaporating the mixed solvent of acetone and water, and repeating the spraying and low-temperature treatment steps multiple times until a graphene oxide interface layer with a thickness of 0.3 μm is formed on the surface of the continuous carbon fibers; and using the continuous carbon fibers with the graphene oxide interface layer formed on the surface to weave a carbon fiber having a density of 0.4 g / cm 3 The preform structure is placed in a high-temperature furnace, and the temperature is raised to 600°C under argon protection at a heating rate of 2°C / minute. Hydrogen is introduced with a hydrogen flow rate of 100 sccm and the temperature is kept constant for 240 minutes to convert the graphene oxide interface layer into a graphene interface layer. The temperature is naturally cooled to room temperature, and the preform is taken out to obtain a carbon fiber preform.

[0082] ② A pyrolytic carbon interface layer with a thickness of 5 μm is deposited on the basis of the graphene interface layer of the carbon fiber of the carbon fiber preform obtained in step ① by chemical vapor deposition to obtain a porous C / C matrix having a graphene / pyrolytic carbon composite interface layer.

[0083] ③ Preparation of HfC interface layer: The porous C / C substrate with the graphene / pyrolytic carbon composite interface layer is placed in a chemical vapor deposition reactor, vacuumed, and the pressure in the reactor is 150Pa. At the same time, the temperature in the reactor is controlled at 1075°C and kept warm for 10 minutes to ensure that the temperature inside the furnace reaches a uniform state. Next, the heated oxygen-free hafnium carbide ceramic precursor is brought into the chemical vapor deposition reactor chamber by nitrogen as a carrier gas. The heating temperature of the oxygen-free hafnium carbide ceramic precursor is controlled at 90°C. While the carrier gas nitrogen continues to carry the oxygen-free hafnium carbide ceramic precursor into the chamber, hydrogen and methane are introduced into the furnace chamber. The volume flow ratio of nitrogen, hydrogen and methane is 10:6:5, of which the nitrogen flow rate is controlled at 2L / min. After the reactor was heated at 1075°C for 1 hour, a 1.0μm-thick hafnium carbide interface layer (HfC interface layer) formed on the graphene / pyrolytic carbon composite interface layer. The temperature was then lowered, and heating of the oxygen-free hafnium carbide ceramic precursor, the introduction of methane, and the introduction of hydrogen were stopped in sequence. Nitrogen was maintained throughout the cooling process until it reached room temperature. The sample was then removed, yielding a carbon / carbon composite material with a graphene / pyrolytic carbon composite interface layer and a hafnium carbide interface layer.

[0084] ④ Preparation of ceramic matrix composites: Using oxygen-free hafnium carbide ceramic precursor as a reactant, the oxygen-free hafnium carbide ceramic precursor was reacted with a carbon / carbon composite material having a graphene / pyrolytic carbon composite interface layer / hafnium carbide interface layer by an impregnation / curing / cracking PIP process to prepare a ceramic matrix composite with a density of 3.3 g / cm 3 Ceramic-based composite materials; in each impregnation / curing / cracking round, the impregnation is first performed by vacuum impregnation, the vacuum impregnation pressure is 200 Pa, and then pressure impregnation is performed, the pressure of pressure impregnation is 2 MPa, the time of each vacuum impregnation is 1.5 hours, the time of each pressure impregnation is 1.5 hours, the temperature of the curing is 280°C, the time of each curing is 3 hours, the curing is carried out in an argon atmosphere, the temperature of the cracking is 1500°C, the time of each cracking is 3 hours, and the cracking is carried out in an argon atmosphere.

[0085] Mechanical property test under high temperature oxygen environment: The ceramic matrix composite material prepared in this comparative example was measured to have a flexural strength of 307 MPa under 1500°C air environment.

[0086] Comparative Example 2

[0087] ① is the same as step ① in Example 1.

[0088] ② is the same as step ② of Example 1.

[0089] ③ is the same as step ③ of Example 1.

[0090] ④ is the same as step ④ of Example 1.

[0091] ⑤ The porous carbon / carbon composite material with the nickel foam removed was immersed in a nitric acid solution with a concentration of 6 mol / L and kept warm at 80°C for 150 min, and then dried in an oven at 80°C for 240 min to obtain a modified carbon / carbon composite material.

[0092] ⑥ Prepare a Hf(NO3)4 aqueous solution with a concentration of 0.1 mol / L, soak the modified carbon / carbon composite material obtained in step ⑤ in the Hf(NO3)4 aqueous solution and pressurize it for 240 min at a pressure of 0.3 MPa, dry it in an 80°C oven for 240 min, then place it in a sintering device, heat it to 600°C under the protection of inert gas argon (heating rate of 5°C / min), keep it at 600°C for 120 minutes, and cool it to room temperature at a rate of 5°C / min.

[0093] ⑦ Repeat step ⑥ multiple times until a carbon / carbon composite material with a hafnium oxide layer having a thickness of 1 μm is obtained.

[0094] ⑧ The carbon / carbon composite material having a hafnium oxide layer with a thickness of 1 μm is placed in a high-temperature device, heated to 1600°C (heating rate of 5°C / min) under the protection of inert gas argon, and maintained at 1600°C for 120 minutes to allow a carbon thermal reduction reaction to occur, so that the hafnium oxide layer is converted into a hafnium carbide layer. The temperature is then cooled to room temperature at a rate of 5°C / min to obtain a carbon / carbon composite material having a hafnium carbide layer with a thickness of 1 μm.

[0095] ⑨ Preparation of ceramic matrix composites: Using oxygen-free hafnium carbide ceramic precursor as a reactant, the oxygen-free hafnium carbide ceramic precursor is reacted with a carbon / carbon composite material having a hafnium carbide layer by an impregnation / curing / cracking process to prepare a ceramic matrix composite with a density of 3.3 g / cm 3 Ceramic-based composite materials; in each impregnation / curing / cracking round, the impregnation is first performed by vacuum impregnation, the vacuum impregnation pressure is 200 Pa, and then pressure impregnation is performed, the pressure of pressure impregnation is 2 MPa, the time of each vacuum impregnation is 1.5 hours, the time of each pressure impregnation is 1.5 hours, the temperature of the curing is 280°C, the time of each curing is 3 hours, the curing is carried out in an argon atmosphere, the temperature of the cracking is 1500°C, the time of each cracking is 3 hours, and the cracking is carried out in an argon atmosphere.

[0096] Mechanical property test under high temperature oxygen environment: The ceramic matrix composite material prepared in this comparative example was measured to have a flexural strength of 286 MPa under 1500°C air environment.

[0097] Parts of the present invention that are not described in detail are well known to those skilled in the art.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a graphene-toughened ceramic-based composite material, characterized in that: The method comprises the following steps: (1) Alternately laminating carbon cloth and nickel foam sheets, and then forming a preform by a puncture process; the thickness of the nickel foam sheets is 0.02-0.08 mm, and the volume of the nickel foam sheets in the preform is 5-20%; (2) depositing pyrolytic carbon and graphene in the preform by chemical vapor deposition to obtain a porous carbon / carbon composite material; the deposition is performed in an atmosphere comprising nitrogen, hydrogen, and methane, wherein the volume flow ratio of the nitrogen, hydrogen, and methane is 10:3:(2-5); (3) soaking the porous carbon / carbon composite material in an acid solution to obtain a porous carbon / carbon composite material from which the nickel foam is removed; (4) using an oxygen-free hafnium carbide ceramic precursor as a reactant, depositing a hafnium carbide interface layer in the porous carbon / carbon composite material from which the nickel foam has been removed by chemical vapor deposition, thereby obtaining a carbon / carbon composite material having a hafnium carbide interface layer; in step (4), heating the oxygen-free hafnium carbide ceramic precursor, and introducing nitrogen as a carrier gas into a chemical vapor deposition furnace, while simultaneously introducing hydrogen and methane into the chemical vapor deposition furnace to deposit the hafnium carbide interface layer; wherein the volume flow ratio of nitrogen, hydrogen, and methane is 10:6:(4-10), and the temperature for depositing the hafnium carbide interface layer is 1020-1550°C; (5) The oxygen-free hafnium carbide ceramic precursor is reacted with the carbon / carbon composite material having the hafnium carbide interface layer by an impregnation pyrolysis method to obtain a graphene-toughened ceramic matrix composite material.

2. The preparation method according to claim 1, wherein: The surface density of the nickel foam sheet is 150-370 g / m 2 .

3. The preparation method according to claim 1, wherein: The density of the preform is 0.8-1.2 g / cm 3 and / or In step (2), the density of the porous carbon / carbon composite material is 0.9-1.3 g / cm 3 .

4. The preparation method according to claim 1, characterized in that In step (2): The deposition temperature is 800-1000° C., and the deposition time is 0.5-2 h.

5. The preparation method according to claim 1, characterized in that In step (3): The acid solution is one or more of hydrochloric acid, nitric acid solution, and sulfuric acid solution; The concentration of the acid solution is not greater than 1 mol / L; and / or The soaking temperature is 25-50° C., and the soaking time is 2-5 hours.

6. The preparation method according to claim 1, wherein: The heating temperature of the oxygen-free hafnium carbide ceramic precursor is 80-100° C. The time for depositing the hafnium carbide interface layer is 0.5-2 hours, and the pressure in the chemical vapor deposition furnace is 20-200 Pa.

7. The preparation method according to claim 1, wherein: The thickness of the hafnium carbide interface layer is 0.5-1.5 μm; and / or The density of the graphene toughened ceramic matrix composite material is 3.1-3.6 g / cm 3 .

8. The preparation method according to any one of claims 1 to 7, characterized in that In step (4) and step (5), the preparation of the oxygen-free hafnium carbide ceramic precursor is as follows: The tetrakis(dimethylamino)hafnium or tetrakis(diethylamino)hafnium is subjected to an amine exchange reaction with an amine compound, and then subjected to reduced pressure distillation to obtain an oxygen-free hafnium carbide ceramic precursor; The amine compound is one or more of di-n-propylamine, diisopropylamine, diallylamine, di-n-butylamine, diisobutylamine, di-n-pentylamine, tetrahydropyrrole, and hexahydropyridine.

9. A graphene-toughened ceramic-based composite material prepared by the preparation method according to any one of claims 1 to 8.

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