Carbon fiber plasticized functional gradient layered ceramic composite material and preparation method thereof

Abstract

The invention discloses a preparation method of a carbon fiber plasticized functional gradient layered ceramic composite material, which comprises the following steps: 1) impregnating carbon fibers in SiO2-BN precursor sol, and carrying out gradient pyrolysis in an inert atmosphere; 2) performing chemical vapor infiltration of silicon carbide on the pyrolyzed carbon fibers; (3) dipping the carbon fibers with the SiC nanowires deposited and permeated on the surfaces into the Al2O3-SiC-TiB2 composite matrix slurry, and drying; and 4) putting the green body of the carbon fiber plasticized functional gradient layered ceramic composite material into a mold, carrying out segmented hot pressing sintering, cooling and taking out to obtain the carbon fiber plasticized functional gradient layered ceramic composite material. The prepared carbon fiber plasticized functional gradient layered ceramic composite material has excellent thermal shock resistance, bending strength, shear strength and fracture toughness.

Description

Technical Field

[0001] This invention belongs to the field of ceramic composite materials technology, specifically relating to a carbon fiber plasticized functional gradient layered ceramic composite material and its preparation method. Background Technology

[0002] Carbon fiber / ceramic composites are a class of advanced composite materials that use carbon fiber as reinforcement and ceramic materials as the matrix. Carbon fiber, as the main load-bearing component, provides the composite material with strength and toughness. When the material is subjected to stress and microcracks develop, the fibers can absorb a large amount of energy through "pull-out effect" and "bridging effect," preventing crack propagation and thus significantly improving the fracture toughness of the material, achieving "toughening of brittle ceramics." The ceramic matrix material protects the fibers from damage caused by external environments (such as oxidation and mechanical wear), transmits and distributes external forces to the fibers, fixes the fiber position, and imparts overall high-temperature stability, corrosion resistance, and hardness to the material.

[0003] However, existing carbon fiber / ceramic composite materials have the following main problems in the preparation process: 1) Because carbon fiber is inert, it has poor wettability with many ceramic matrices, resulting in weak interfacial bonding. Especially under high temperature conditions, the difference in thermal expansion coefficients between carbon fiber and ceramic matrix leads to generally low interfacial shear strength, which cannot meet the test requirements of ASTM D2344 standard, causing the risk of interlaminar cracking during material service; 2) There is a limit to the improvement of fracture toughness by using a single toughening mechanism (such as fiber pull-out or nanoparticle dispersion), and the increase in fracture toughness of conventional processes is relatively low; 3) Hot pressing sintering process requires long-term heat preservation, usually 8-10 hours, resulting in long production cycle and high energy consumption, which seriously restricts the cost control of large-scale production.

[0004] In view of the above problems, it would be of substantial benefit in the field to prepare a carbon fiber / ceramic composite material with excellent shear strength and fracture toughness. Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the main objective of this invention is to provide a method for preparing carbon fiber-reinforced functionally graded layered ceramic composite materials.

[0006] The objective of this invention is achieved through the following technical solution: A method for preparing a carbon fiber plasticized functionally graded layered ceramic composite material includes the following steps: 1) The carbon fiber was impregnated in SiO2-BN precursor sol and subjected to gradient pyrolysis under an inert atmosphere to obtain pyrolysis-treated carbon fiber. 2) The pyrolysis-treated carbon fibers were subjected to silicon carbide chemical vapor infiltration to obtain carbon fibers with SiC nanowires deposited on the surface. 3) The carbon fiber with SiC nanowires deposited on its surface prepared in step 2) is impregnated with Al2O3-SiC-TiB2 composite matrix slurry, dried, to obtain a green body of carbon fiber plasticized functional gradient layered ceramic composite material. 4) Place the carbon fiber plasticized functional gradient layered ceramic composite green body into a mold, perform segmented hot pressing sintering, cool and remove to obtain carbon fiber plasticized functional gradient layered ceramic composite.

[0007] In some specific embodiments, the SiO2-BN precursor sol described in step 1) is prepared by the following method: tetraethyl orthosilicate is mixed with ethanol to obtain a transparent silicate phase; boric acid and urea are dissolved in deionized water and cooled to room temperature to obtain an aqueous BN phase; the aqueous BN phase is poured into the silicate phase under stirring, the pH of the system is adjusted to be stable at 3.7-4.0, and stirring is continued at room temperature until a clear solution is obtained, which is the SiO2-BN precursor sol.

[0008] In some specific implementations, the gradient pyrolysis process described in step 1) is divided into two stages: the first stage is a heating rate of 3-5℃ / min, from room temperature to 500-700℃ and then maintained for 30-45min; the second stage is a heating rate of 8-10℃ / min, from 500-700℃ to 800-1000℃ and maintained for 15-25min.

[0009] In some specific embodiments, the process parameters for chemical vapor infiltration in step 2) are as follows: under the conditions of temperature of 950±10℃ and pressure of 5-8kPa, a mixed gas of CH3SiCl3 / H2 with a volume ratio of 1:(15-20) is introduced, and the deposition time is 2-4h.

[0010] In some specific embodiments, the Al2O3-SiC-TiB2 composite matrix slurry described in step 3) is prepared by the following method: using ammonium polyacrylate as a dispersant and deionized water as a solvent, ceramic powder composed of Al2O3, SiC and TiB2 particles is added according to the required proportion and mixed evenly to obtain a slurry with uniformly dispersed ceramic powder. The pH value of the slurry is adjusted by ammonia water, and then ball milling and vacuum degassing are performed sequentially to finally obtain the Al2O3-SiC-TiB2 composite matrix slurry.

[0011] In some specific embodiments, the initial solid content of the Al2O3-SiC-TiB2 composite matrix slurry is 20-50%, the pH value is adjusted to a range of 8.5-9.5, and in the ceramic powder composed of Al2O3-SiC-TiB2, the mass fraction of TiB2 particles is 8-12%, and the molar ratio of SiC particles to Al2O3 particles is (1-1.2):1.

[0012] In some specific embodiments, the impregnation process in step 3) is as follows: the Al2O3-SiC-TiB2 composite matrix slurry is placed in a vacuum ultrasonic machine, and the carbon fibers with SiC nanowires deposited on the surface obtained in step 2) are impregnated in the Al2O3-SiC-TiB2 composite matrix slurry. Vacuum is drawn, and ultrasonic treatment is performed for 10 min to 30 min under a vacuum degree of 1 Pa to 5 Pa. After ultrasonic treatment, the carbon fibers are taken out and dried to obtain a green body of carbon fiber plasticized functional gradient layered ceramic composite material.

[0013] In some specific embodiments, the segmented hot pressing sintering described in step 4) specifically involves: applying a pressure of 9 MPa to 11 MPa to the green blank in the mold under an inert atmosphere with a vacuum degree of 1 Pa to 10 Pa, then raising the temperature to 750-850°C at a heating rate of 5-8°C / min and maintaining it for 40-80 min for pre-sintering; continuing to raise the temperature to 800-1200°C at 10-12°C / min, raising the pressure to 23-27 MPa, and holding it for 30-60 min for the main sintering stage I; then raising the temperature to 1200-1550°C at 8-12°C / min, raising the pressure to 45 MPa, and holding it for 20-60 min for the main sintering stage II.

[0014] In some specific implementations, the cooling process in step 4) is as follows: cooling with the furnace, gradually reducing the pressure to 40MPa and maintaining it when the temperature drops to 600℃, and exiting the furnace when the temperature is below 200℃.

[0015] As part of the same inventive concept, the present invention also provides a carbon fiber plasticized functional gradient layered ceramic composite material.

[0016] Compared with the prior art, the present invention has at least the following advantages: The preparation method of the present invention first involves gradient pyrolysis of carbon fibers impregnated in SiO2-BN precursor sol, resulting in a gradient distribution of BN nanosheets along the fiber axis with a denser outer layer and a sparser inner layer. The high BN nanosheet volume content in the outer layer can effectively reduce thermal expansion mismatch, while the low BN volume content in the inner layer can ensure the bonding strength between the carbon fibers and the ceramic matrix.

[0017] 2) The preparation method of the present invention further involves chemical vapor infiltration of silicon carbide into the pyrolyzed carbon fibers to deposit carbon fibers with SiC nanowires on the surface. The SiC nanowires can serve as an interface layer, providing technical support for improving the shear strength, fracture toughness and thermal shock resistance of the composite material.

[0018] 3) The preparation method of this invention involves segmented hot-pressing sintering of a carbon fiber plasticized functional gradient layered ceramic composite green body. Specifically, firstly, through pre-sintering, SiC nanowires are embedded into the micropores on the surface of BN nanosheets, while the BN nanosheets are further oriented along the fiber axis under pressure, providing technical support for subsequently reducing the radial thermal expansion coefficient. Then, in the main sintering stage I, Al2O3 and SiC begin surface diffusion, and solid-state sintering necks form between the ceramic matrix particles and the nanowire nodes. Furthermore, in the main sintering stage II, TiB2 dissolves and reprecipitates to form nanocrystals along the surface of the SiC nanowires, while a small amount of mullite transition phase is generated in the Al2O3-SiC with a molar ratio of 1.1:1, forming a Si-Al-ONB glass film with the outer SiO2-BN gradient layer of the fiber, achieving chemical bonding. Finally, the sintering is carried out at 40 MPa. By holding the pressure at 600℃, the difference in cooling shrinkage is "absorbed" into the elastic deformation of the nanowires, thereby preparing a ceramic composite material with excellent shear strength, fracture toughness and thermal shock resistance. Moreover, the total time of the hot pressing process of this preparation method is generally 4-6 hours, which greatly reduces the hot pressing cycle and reduces production energy consumption. Detailed Implementation

[0019] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0020] When a quantity, concentration, or other value or parameter is described as a range, preferred range, or preferred upper and lower limits, it should be understood that it is equivalent to specifically disclosing any range by combining any pair of upper or preferred values ​​with any lower or preferred values, regardless of whether the range is specifically disclosed. Unless otherwise stated, the numerical range values ​​listed herein include the endpoints of the range and all integers and fractions within that range.

[0021] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by weight.

[0022] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.

[0023] In the following embodiments, the carbon fiber has a diameter of 7-100 μm and an aspect ratio of ≥100; The SiO2-BN precursor sol can be prepared by other methods in the prior art, or by the following method: 1) Dissolve 180g of tetraethyl orthosilicate in 200g of ethanol to obtain a transparent silicone ester phase; 2) Dissolve 28g of boric acid and 12g of urea in 300g of deionized water and stir until completely dissolved until the solution is clear and transparent to obtain the BN precursor aqueous phase; 3) While maintaining stirring, pour the BN precursor aqueous phase into the silicone ester phase all at once, and then add 0.1 mol L⁻¹ dropwise. -1 Add nitric acid (L) to adjust the pH of the system to 3.8 ± 0.2, and continue stirring at room temperature for 30 min to obtain a clear and transparent SiO2-BN precursor sol.

[0024] In the following embodiments, the Al2O3-SiC-TiB2 composite matrix slurry is prepared by the following method: using ammonium polyacrylate as a dispersant and deionized water as a solvent, ceramic powder composed of Al2O3, SiC, and TiB2 particles is added according to the required proportion and mixed evenly to obtain a slurry with uniformly dispersed ceramic powder. The pH value of the slurry is adjusted by ammonia water, and then ball milling and vacuum degassing are performed sequentially to finally obtain an Al2O3-SiC-TiB2 composite matrix slurry with an initial solid content of 25% and a pH value of 9.0. In the ceramic powder composed of Al2O3-SiC-TiB2, the mass fraction of TiB2 particles is 10%, and the molar ratio of SiC particles to Al2O3 particles is 1.1:1.

[0025] Example 1 This embodiment provides a method for preparing carbon fiber plasticized functionally graded layered ceramic composite materials, which includes the following steps: 1) The carbon fiber is impregnated in SiO2-BN precursor sol and subjected to gradient pyrolysis under an inert atmosphere. The gradient pyrolysis is specifically divided into two stages: the first stage: the heating rate is 3℃ / min, and the temperature is raised from room temperature to 500℃ and held for 45min; the second stage: the heating rate is 8℃ / min, and the temperature is raised from 500℃ to 800℃ and held for 25min, to obtain the pyrolyzed carbon fiber. 2) Pyrolytic carbon fibers were subjected to chemical vapor infiltration of silicon carbide under the conditions of 950±10℃ and 6kPa, with a volume ratio of 1:15 of CH3SiCl3 / H2 mixed gas, and deposited for 3h to obtain carbon fibers with SiC nanowires deposited on the surface. 3) Place the Al2O3-SiC-TiB2 composite matrix slurry in a vacuum ultrasonic machine, and then impregnate the carbon fibers with SiC nanowires deposited on the surface obtained in step 2) into the Al2O3-SiC-TiB2 composite matrix slurry. Vacuum is drawn, and ultrasonic treatment is performed for 25 minutes under a vacuum degree of 3 Pa. After ultrasonic treatment, the material is removed and dried to obtain a green body of carbon fiber plasticized functional gradient layered ceramic composite material. 4) The carbon fiber plasticized functional gradient layered ceramic composite green body is placed in a mold. Under an inert atmosphere with a vacuum degree of 5 Pa, a pressure of 9 MPa is applied to the green body in the mold. Then, the temperature is increased to 750℃ at a heating rate of 5℃ / min and held for 60 min for pre-sintering. The temperature is then increased to 800℃ at a rate of 10℃ / min and the pressure is increased to 23 MPa. The temperature is held for 60 min for the main sintering stage I. The temperature is then increased to 1445℃ at a rate of 8℃ / min and the pressure is increased to 45 MPa. The temperature is held for 45 min for the main sintering stage II. Finally, the furnace is cooled. When the temperature drops to 600℃, the pressure is gradually reduced to 40 MPa and maintained. The furnace is then removed from the furnace when the temperature is below 200℃ to obtain the carbon fiber plasticized functional gradient layered ceramic composite.

[0026] Example 2 This embodiment provides a method for preparing carbon fiber plasticized functionally graded layered ceramic composite materials, which includes the following steps: 1) The carbon fiber is impregnated in SiO2-BN precursor sol and subjected to gradient pyrolysis under an inert atmosphere. The gradient pyrolysis is specifically divided into two stages: the first stage: the heating rate is 4℃ / min, and the temperature is raised from room temperature to 600℃ and held for 40min; the second stage: the heating rate is 9℃ / min, and the temperature is raised from 600℃ to 900℃ and held for 20min, to obtain the pyrolyzed carbon fiber. 2) Pyrolytic carbon fibers were subjected to chemical vapor infiltration of silicon carbide under the conditions of 950±10℃ and 6kPa, with a volume ratio of 1:16 of CH3SiCl3 / H2 mixed gas, and deposited for 3h to obtain carbon fibers with SiC nanowires deposited on the surface. 3) Place the Al2O3-SiC-TiB2 composite matrix slurry in a vacuum ultrasonic machine, and then impregnate the carbon fibers with SiC nanowires deposited on the surface obtained in step 2) into the Al2O3-SiC-TiB2 composite matrix slurry. Vacuum is drawn, and ultrasonic treatment is performed for 20 minutes under a vacuum degree of 3 Pa. After ultrasonic treatment, the material is removed and dried to obtain a green body of carbon fiber plasticized functional gradient layered ceramic composite material. 4) The carbon fiber plasticized functional gradient layered ceramic composite green body is placed in a mold. Under an inert atmosphere with a vacuum degree of 6 Pa, a pressure of 10 MPa is applied to the green body in the mold. Then, the temperature is increased to 800℃ at a heating rate of 6℃ / min and held for 60 min for pre-sintering. The temperature is then increased to 1000℃ at a rate of 11℃ / min and the pressure is increased to 25 MPa. The temperature is held for 45 min for the main sintering stage I. The temperature is then increased to 1550℃ at a rate of 10℃ / min and the pressure is increased to 45 MPa. The temperature is held for 60 min for the main sintering stage II. Finally, the furnace is cooled. When the temperature drops to 600℃, the pressure is gradually reduced to 40 MPa and maintained. The furnace is then removed from the furnace when the temperature is below 200℃ to obtain the carbon fiber plasticized functional gradient layered ceramic composite.

[0027] Example 3 This embodiment provides a method for preparing carbon fiber plasticized functionally graded layered ceramic composite materials, which includes the following steps: 1) The carbon fiber is impregnated in SiO2-BN precursor sol and subjected to gradient pyrolysis under an inert atmosphere. The gradient pyrolysis is specifically divided into two stages: the first stage: the heating rate is 5℃ / min, and the temperature is raised from room temperature to 700℃ and held for 30min; the second stage: the heating rate is 10℃ / min, and the temperature is raised from 700℃ to 1000℃ and held for 15min, to obtain the pyrolyzed carbon fiber. 2) Pyrolytic carbon fibers were subjected to chemical vapor infiltration of silicon carbide under the conditions of 950±10℃ and 6kPa, with a volume ratio of 1:16 of CH3SiCl3 / H2 mixed gas, and deposited for 3h to obtain carbon fibers with SiC nanowires deposited on the surface. 3) Place the Al2O3-SiC-TiB2 composite matrix slurry in a vacuum ultrasonic machine, and then impregnate the carbon fibers with SiC nanowires deposited on the surface obtained in step 2) into the Al2O3-SiC-TiB2 composite matrix slurry. Vacuum is drawn, and ultrasonic treatment is performed for 20 minutes under a vacuum degree of 3 Pa. After ultrasonic treatment, the material is removed and dried to obtain a green body of carbon fiber plasticized functional gradient layered ceramic composite material. 4) The green body of the carbon fiber plasticized functional gradient layered ceramic composite material was placed in a mold. Under an inert atmosphere with a vacuum of 6 Pa, a pressure of 11 MPa was applied to the green body in the mold. Then, the temperature was increased to 850 °C at a heating rate of 8 °C / min and held for 60 min for pre-sintering. The temperature was then increased to 1200 °C at a rate of 12 °C / min and the pressure was increased to 27 MPa. The temperature was held for 45 min for the main sintering stage I. The temperature was then increased to 1550 °C at a rate of 12 °C / min and the pressure was increased to 45 MPa. The temperature was held for 60 min for the main sintering stage II. Finally, the furnace was cooled. When the temperature dropped to 600 °C, the pressure was gradually reduced to 40 MPa and held. The furnace was then removed from the furnace when the temperature was below 200 °C to obtain the carbon fiber plasticized functional gradient layered ceramic composite material.

[0028] Performance testing: 1) Performance indicators of carbon fiber plasticized functionally graded layered ceramic composites This application uses Example 2 as an example to test the flexural strength (ASTM C1341), fracture toughness (ISO 14577-1), and thermal shock cycle count (GB / T 16536) of the prepared carbon fiber plasticized functionally graded layered ceramic composite material. The results are shown in Table 1: Table 1: Performance Indicators of Carbon Fiber Plasticized Functionally Graded Layered Ceramic Composites Note: The temperature range for thermal shock cycles is room temperature - 1000℃. The evaluation method is the strength decay method: after different number of cycles, samples are taken for bending strength testing; when the residual strength retention rate (η) is less than 80%, the corresponding number of cycles is the number of thermal shock cycles.

[0029] As can be seen from the data in Table 1, the carbon fiber plasticized functional gradient layered ceramic composite material obtained by the preparation method of this application has excellent thermal shock resistance, as well as excellent flexural strength, shear strength and fracture toughness.

[0030] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for producing a carbon fiber plasticized functionally graded layered ceramic composite material, characterized by, The method comprises the following steps: 1) carbon fibers are immersed in SiO2-BN precursor sol, and gradient pyrolysis is performed in an inert atmosphere to obtain pyrolysis-treated carbon fibers; 2) chemical vapor infiltration of silicon carbide is performed on the pyrolysis-treated carbon fibers to obtain carbon fibers with SiC nanowires deposited and infiltrated on the surface; 3) the carbon fibers with SiC nanowires deposited and infiltrated on the surface prepared in step 2) are immersed in Al2O3-SiC-TiB2 composite matrix slurry, and dried to obtain a green body of carbon fiber plasticized functional gradient layered ceramic composite material; 4) the green body of carbon fiber plasticized functional gradient layered ceramic composite material is placed in a mold, and is subjected to step-by-step hot-pressing sintering, and is cooled and taken out to obtain a carbon fiber plasticized functional gradient layered ceramic composite material.

2. The method for preparing carbon fiber plasticized functionally graded layered ceramic composite material according to claim 1, characterized in that, The SiO2-BN precursor sol in step 1) is prepared by the following method: ethanol and tetraethyl orthosilicate are uniformly mixed to obtain a transparent silicon ester phase; and boric acid and urea are dissolved in deionized water, and cooled to room temperature to form a BN aqueous phase; the BN aqueous phase is poured into the silicon ester phase under stirring, the pH of the system is adjusted and stabilized at 3.7-4.0, and the stirring is continued at room temperature until a clear solution is obtained, thereby obtaining the SiO2-BN precursor sol.

3. The method for preparing carbon fiber plasticized functionally graded layered ceramic composite material according to claim 1, characterized in that, The gradient pyrolysis in step 1) has the following specific process: the first stage is to increase the temperature at a rate of 3-5 ℃ / min, and then maintain the temperature at 500-700 ℃ for 30-45 min; the second stage is to increase the temperature at a rate of 8-10 ℃ / min, and then maintain the temperature at 800-1000 ℃ for 15-25 min.

4. The method for preparing carbon fiber plasticized functionally graded layered ceramic composite material according to claim 1, characterized in that, The process parameters of the chemical vapor infiltration in step 2) are as follows: under the conditions of a temperature of 950±10 ℃ and a pressure of 5-8 kPa, a CH3SiCl3 / H2 mixed gas with a volume ratio of 1: (15-20) is introduced, and the deposition time is 2-4 h.

5. The method for preparing carbon fiber plasticized functionally graded layered ceramic composite material according to claim 4, characterized in that, The Al2O3-SiC-TiB2 composite matrix slurry in step 3) is prepared by the following method: ammonium polyacrylate is used as a dispersant, deionized water is used as a solvent, ceramic powder composed of Al2O3, SiC and TiB2 particles is added in a proportion, and then mixed uniformly to obtain a slurry in which the ceramic powder is uniformly dispersed, the pH value of the slurry is adjusted by ammonia water, and then ball milling treatment and vacuum debubbling are sequentially performed to finally obtain the Al2O3-SiC-TiB2 composite matrix slurry.

6. The method for preparing carbon fiber plasticized functionally graded layered ceramic composite material according to claim 4, characterized in that, The initial solid content of the Al2O3-SiC-TiB2 composite matrix slurry is 20-50%, the adjusted pH value is in the range of 8.5-9.5, and in the ceramic powder composed of Al2O3, SiC and TiB2, the mass fraction of TiB2 particles is 8-12%, and the molar ratio of SiC particles to Al2O3 particles is (1-1.2):

1.

7. The method for preparing carbon fiber plasticized functionally graded layered ceramic composite material according to claim 1, characterized in that, The impregnation process in step 3) is as follows: the Al2O3-SiC-TiB2 composite matrix slurry is placed in a vacuum ultrasonic machine, and the carbon fibers with the surface deposited and permeated with SiC nanowires obtained in step 2) are impregnated in the Al2O3-SiC-TiB2 composite matrix slurry, vacuum is drawn, ultrasonic treatment is performed for 10-30 min under the condition of a vacuum degree of 1-5 Pa, and then the carbon fiber plasticized functional gradient layered ceramic composite green body is obtained after drying.

8. The method for preparing carbon fiber plasticized functionally graded layered ceramic composite material according to claim 1, characterized in that, The segmented hot-pressing sintering in step 4) is as follows: under the condition of an inert atmosphere with a vacuum degree of 1-10 Pa, a pressure of 9-11 MPa is applied to the green body in the mold, then the temperature is raised to 750-850 ℃ at a temperature raising rate of 5-8 ℃ / min, and pre-sintering is performed for 40-80 min; then the temperature is raised to 800-1200 ℃ at a temperature raising rate of 10-12 ℃ / min, the pressure is raised to 23-27 MPa, and main sintering stage I is performed for 30-60 min; then the temperature is raised to 1200-1550 ℃ at a temperature raising rate of 8-12 ℃ / min, the pressure is raised to 45 MPa, and main sintering stage II is performed for 20-60 min.

9. The method for preparing carbon fiber plasticized functionally graded layered ceramic composite material according to claim 4, characterized in that, The cooling process in step 4) is as follows: furnace cooling is performed, the pressure is gradually released to 40 MPa when the temperature is reduced to 600 ℃, and then the temperature is maintained, and the furnace is discharged when the temperature is lower than 200 ℃.

10. A carbon fiber plasticized functional gradient layered ceramic composite material prepared by the preparation method according to any one of claims 1-9.

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