阅读说明：本技术 制备(SiCNW)/(ZrC基体-涂层一体化)改性C/C复合材料的方法 (Preparation (SiC)NW) Method for modifying C/C composite material (ZrC matrix-coating integration) ) 是由 李贺军 田新发 史小红 林红娇 杨莉 于 2020-12-18 设计创作，主要内容包括：本发明涉及一种制备(SiC-(NW))/(ZrC基体-涂层一体化)改性C/C复合材料的方法,通过预先制备SiC纳米线骨架,使得通过PIP法制备ZrC陶瓷掺杂基体的同时可以在基体表面形成ZrC(SiC)陶瓷涂层。该方法能够使ZrC(SiC)陶瓷涂层与掺杂基体一体化成型,既能有效阻隔氧气气氛和高速粒子对基体的侵蚀,又能降低基体的氧化活性,同时缓解基体与涂层之间的热膨胀系数不匹配问题,从内至外整体上提升C/C复合材料长时间的抗烧蚀能力。本发明操作简单、制备温度较低、对基体损伤小、成本低廉,可为C/C复合材料在高温烧蚀环境中的应用提供一定的理论与实验助力,具有良好的经济及社会效益。(The invention relates to a method for preparing (SiC) NW ) The method for modifying the C/C composite material by the ZrC matrix-coating integration comprises the step of preparing the SiC nanowire framework in advance, so that the ZrC ceramic doped matrix is prepared by a PIP method, and the ZrC (SiC) ceramic coating can be formed on the surface of the matrix. The method can integrally form the ZrC (SiC) ceramic coating and the doped matrix, effectively prevent the erosion of oxygen atmosphere and high-speed particles to the matrix, reduce the oxidation activity of the matrix, simultaneously relieve the problem of mismatch of thermal expansion coefficients between the matrix and the coating, and integrally improve the long-time ablation resistance of the C/C composite material from inside to outside. The method has the advantages of simple operation, low preparation temperature, small damage to the matrix and low cost, can provide certain theoretical and experimental assistance for the application of the C/C composite material in a high-temperature ablation environment, and has good economic and social benefits.)

1. Preparation of (SiC)_NW) The method for modifying the C/C composite material (ZrC matrix-coating integration) is characterized by comprising the following steps:

the SiC nanowire is an epitaxial framework in a precursor impregnation cracking method, a ZrC matrix and a coating are integrally formed, and the method comprises the following steps:

step 1, preparing a SiC nanowire framework layer: mixing ethyl orthosilicate, absolute ethyl alcohol and deionized water according to a ratio of 5-9: 2-4: 1-3, adding hydrochloric acid to regulate pH value to 3-5, and stirring at 60-90 ℃ for 1-4h to obtain silica sol;

naturally dipping the low-density C/C composite material in silica sol for 5-14 days, depositing pyrolytic carbon for 0.5-5h by a chemical vapor infiltration method after drying, finally preserving the thermal insulation for 2-4h at the temperature of 1700 ℃ in a heat treatment furnace, and cooling to the normal temperature to generate SiC framework layers in the low-density C/C composite material and on the surface of the low-density C/C composite material;

step 2, dipping a ZrC precursor:

mixing xylene and a ZrC precursor at a ratio of 2: 4-7, ultrasonically mixing, and stirring in a magnetic stirrer for more than 1h to prepare a diluted ZrC precursor solution;

putting the low-density C/C composite material containing the SiC nanowire framework layer into a ZrC precursor solution, keeping the solution for 0.5 to 1 hour under vacuum of-0.08 to 0.1Mpa, taking out the solution, and putting the solution into a drying box to dry for 2 to 4 days at the temperature of 60 to 90 ℃;

repeating the step for 6-9 times;

step 3, shaping of a precursor: putting the material treated in the step 2 into a chemical vapor infiltration furnace, heating to 1000-1200 ℃ at 4-6 ℃/min under the protection of 100-300mL/min argon, introducing methyl trichlorosilane and hydrogen, keeping the temperature for 0.5-5h, closing a methyl trichlorosilane and hydrogen gas valve, cooling to room temperature, taking out, and finishing the deposition of silicon carbide;

repeating the deposition step and the dipping step for 3-5 times;

step 4, heat treatment: putting the material processed in the step 3 into a horizontal heat treatment furnace, heating to 1400 ℃ and 1600 ℃ at the speed of 4-6 ℃/min under the argon atmosphere, preserving the heat for 2-4h, cooling to room temperature, and taking out to obtain (SiC)_NW) And (ZrC matrix-coating integration) modifying the C/C composite material.

2. Preparation of (SiC) according to claim 1_NW) The method for modifying the C/C composite material (ZrC matrix-coating integration) is characterized by comprising the following steps: step 2 is ultrasonic mixing for half an hour.

3. Preparation of (SiC) according to claim 1_NW) The method for modifying the C/C composite material (ZrC matrix-coating integration) is characterized by comprising the following steps: said step 3 methylThe flow rate of the trichlorosilane is 0.1-0.5 g/min.

4. Preparation of (SiC) according to claim 1_NW) The method for modifying the C/C composite material (ZrC matrix-coating integration) is characterized by comprising the following steps: the flow rate of the hydrogen in the step 3 is 100-200 mL/min.

Technical Field

The invention belongs to the technical field of material thermal protection, and relates to a method for preparing (SiC)_NW) /(ZrC matrix-coating integration) method for modifying C/C composite material, in particular to a method for preparing (SiC) composite material by SiC nanowire framework improved precursor impregnation cracking (PIP)_NW) /(ZrC matrix-coating integrationChemical) modification of the C/C composite.

Background

The carbon/carbon (C/C) composite material has a series of advantages of low density, high strength, high modulus, corrosion resistance, wear resistance and the like, and has the characteristic of no reduction and no reverse rise of mechanical properties at high temperature, so that the carbon/carbon (C/C) composite material becomes one of the most potential candidate materials for high-temperature thermal structural components in the aerospace field. However, the C/C composite material is easy to oxidize at high temperature, and the mechanical property of the C/C composite material is rapidly reduced along with the increase of the oxidation speed, so that the application of the C/C composite material in an oxygen-containing atmosphere is severely limited. Meanwhile, the material is often impacted by high-temperature and high-speed airflow in practical application, so that the ablation resistance of the material must be improved.

The conventional methods at home and abroad comprise a matrix modification method and a coating method. Document 1(H.Zhou, D.Ni, P.He, J.Yang, J.Hu, S.Dong.Abslation viewer of C/C-ZrC and C/SiC-ZrC compositions modulated by a joint process of slip approximation and chemical vapor injection [ J.]The influence of ZrC and SiC doped matrix modification on the ablation performance of the C/C composite material is researched by Ceramics International,2018,44(5): 4777-4782), and the C/C-SiC-ZrC composite material can form a Zr-Si-O glass layer embedded structure in the ablation process, and liquid SiO can be formed₂And ZrSiO₄，ZrO₂The substances effectively block the oxygen from entering and can slow down but cannot thoroughly prevent the oxidative damage of the matrix and the fibers. Document 2(S.L.Wang, K.Z.Li, H.J.Li, Y.L.Zhang, T.Feng, Structure evolution and interaction behavior of ZrC coating on C/C compositions under single and cyclic oxy ethylene drive environment [ J.]Ceramics International 2014,40 16003-₂、ZrC_xO_yThe coating can effectively close pores to prevent oxygen from diffusing into the coating, but the coating is difficult to completely prevent oxygen from diffusing and cracking after multiple ablations, and oxidation extends into the coating, but a matrix is not damaged. The two methods have respective characteristics, and the matrix modification method starts from improving the self oxidation resistance of the matrix of the material and has higher impact resistance and thermal shock resistance, but the method has the advantages of improving the self oxidation resistance of the matrix of the materialThe oxygen is difficult to be completely isolated, and the matrix and the fiber are difficult to avoid chemical erosion and mechanical impact; the coating process is capable of effectively isolating the oxidizing atmosphere from contact with the substrate by forming a heat and oxygen barrier through the coating, but cracks and even spalling are often produced due to thermal mismatch due to mismatch in the coefficient of thermal expansion of the ceramic coating and the carbon substrate. Therefore, the combination of the two can increase the thermal expansion coefficient of the substrate, reduce the possibility of coating peeling, increase the isolation of the substrate from oxygen and improve the long-term ablation resistance of the material from inside to outside. However, the modification of the matrix and the preparation of the coating are both prepared separately at present, so that an obvious gap still exists between the doped matrix and the coating, the connection performance and the fusion performance of the doped matrix and the coating are poor, and the advantage of combining the two methods is difficult to be fully exerted.

The precursor impregnation cracking (PIP) method is widely applied to matrix modification of C/C composite materials, and has the advantages of low cost, simple operation, short preparation period, lower preparation temperature and uniform distribution of doped ceramic matrixes. Since the precursor is adsorbed on the carbon fiber during the impregnation process, the converted ceramic can only exist inside the carbon fiber preform. The SiC nanowires are innovatively used as the epitaxial skeleton on the surface of the C/C composite material, so that the nanowires can be used as adsorbates in the dipping process of the precursor, the ceramic coating is generated on the surface while the nanowire is converted into the ceramic matrix through heat treatment, the nanowire and the ceramic matrix are homologous, and the SiC nanowires have compatibility and can further improve the ablation resistance of the material. The invention has obvious theoretical and experimental reference values for further improving the ablation resistance of the C/C composite material and expanding the application field of the composite material.

Disclosure of Invention

Technical problem to be solved

In order to avoid the disadvantages of the prior art, the invention provides a method for preparing (SiC)_NW) The preparation method has the advantages of simple operation, low cost and low preparation temperature, can effectively improve the long-time ablation resistance of the C/C composite material, and has good economic and social benefits.

Technical scheme

Preparation of (SiC)_NW) The method for modifying the C/C composite material (ZrC matrix-coating integration) is characterized by comprising the following steps: the SiC nanowire is an epitaxial framework in a precursor impregnation cracking method, a ZrC matrix and a coating are integrally formed, and the method comprises the following steps:

step 1, preparing a SiC nanowire framework layer: mixing ethyl orthosilicate, absolute ethyl alcohol and deionized water according to a ratio of 5-9: 2-4: 1-3, adding hydrochloric acid to regulate pH value to 3-5, and stirring at 60-90 ℃ for 1-4h to obtain silica sol;

naturally dipping the low-density C/C composite material in silica sol for 5-14 days, depositing pyrolytic carbon for 0.5-5h by a chemical vapor infiltration method after drying, finally preserving the thermal insulation for 2-4h at the temperature of 1700 ℃ in a heat treatment furnace, and cooling to the normal temperature to generate SiC framework layers in the low-density C/C composite material and on the surface of the low-density C/C composite material;

step 2, dipping a ZrC precursor:

mixing xylene and a ZrC precursor at a ratio of 2: 4-7, ultrasonically mixing, and stirring in a magnetic stirrer for more than 1h to prepare a diluted ZrC precursor solution;

putting the low-density C/C composite material containing the SiC nanowire framework layer into a ZrC precursor solution, keeping the solution for 0.5 to 1 hour under vacuum of-0.08 to 0.1Mpa, taking out the solution, and putting the solution into a drying box to dry for 2 to 4 days at the temperature of 60 to 90 ℃;

repeating the step for 6-9 times;

step 3, shaping of a precursor: putting the material treated in the step 2 into a chemical vapor infiltration furnace, heating to 1000-1200 ℃ at 4-6 ℃/min under the protection of 100-300mL/min argon, introducing methyl trichlorosilane and hydrogen, keeping the temperature for 0.5-5h, closing a methyl trichlorosilane and hydrogen gas valve, cooling to room temperature, taking out, and finishing the deposition of silicon carbide;

repeating the deposition step and the dipping step for 3-5 times;

step 4, heat treatment: putting the material processed in the step 3 into a horizontal heat treatment furnace, heating to 1400 ℃ and 1600 ℃ at the speed of 4-6 ℃/min under the argon atmosphere, preserving the heat for 2-4h, cooling to room temperature, and taking out to obtain (SiC)_NW) /(ZrC matrix-coating integration) Modified C/C composite materials.

Step 2 is ultrasonic mixing for half an hour.

The flow rate of the methyl trichlorosilane in the step 3 is 0.1-0.5 g/min.

The flow rate of the hydrogen in the step 3 is 100-200 mL/min.

Advantageous effects

The invention provides a method for preparing (SiC)_NW) The method for modifying the C/C composite material by the ZrC matrix-coating integration comprises the step of preparing the SiC nanowire framework in advance, so that the ZrC ceramic doped matrix is prepared by a PIP method, and the ZrC (SiC) ceramic coating can be formed on the surface of the matrix. The method can integrally form the ZrC (SiC) ceramic coating and the doped matrix, effectively prevent the erosion of oxygen atmosphere and high-speed particles to the matrix, reduce the oxidation activity of the matrix, simultaneously relieve the problem of mismatch of thermal expansion coefficients between the matrix and the coating, and integrally improve the long-time ablation resistance of the C/C composite material from inside to outside. The method has the advantages of simple operation, low preparation temperature, small damage to the matrix and low cost, can provide certain theoretical and experimental assistance for the application of the C/C composite material in a high-temperature ablation environment, and has good economic and social benefits.

Detailed Description

The invention will now be further described with reference to the examples:

the raw materials used in the invention are: low-density C/C composite material, ethyl orthosilicate, absolute ethyl alcohol, hydrochloric acid, argon, methyltrichlorosilane, hydrogen, organic zirconium precursor, xylene and the like.

The invention uses equipment: chemical deposition furnaces, electromagnetic stirrers, ovens, vacuum impregnation tanks, heat treatment furnaces, and the like.

Example 1

Cutting the low density C/C composite material into phi 28 x 10mm³The cylinder is cleaned by ultrasonic cleaning for later use. Sequentially mixing ethyl orthosilicate, absolute ethyl alcohol and deionized water according to the weight ratio of about 6: 3: 1, regulating the pH value to 3 by using hydrochloric acid, and stirring for 2 hours at 60 ℃ to obtain silica sol. Placing the low-density C/C composite material into silica sol for natural immersion for 7 days, drying and then introducingDepositing pyrolytic carbon for 1h by chemical vapor infiltration. And finally, preserving the heat for 2h at 1500 ℃ in a heat treatment furnace, cooling to the normal temperature, and then putting into ZrC precursor impregnation liquid. Impregnating solution of a ZrC precursor is prepared by mixing xylene and the ZrC precursor in a ratio of 2: 4, performing ultrasonic treatment for half an hour, and then putting the mixture into a magnetic stirrer to stir for more than 1 hour to prepare the product. And then putting the beaker filled with the sample and ZrC precursor impregnation liquid into a vacuum impregnation box, vacuumizing to-0.08 MPa, keeping for 0.5h, taking out, and putting into a drying box to dry for 2 days at 80 ℃. And repeating the impregnation step for 6 times, then placing the mixture into a chemical vapor infiltration furnace, raising the temperature to 1100 ℃ at 4 ℃/min under the protection of argon (100mL/min), introducing methyl trichlorosilane (1g/min) and hydrogen (100mL/min), keeping the temperature for 1h, closing a methyl trichlorosilane and hydrogen gas valve, cooling to room temperature, and taking out. Repeating the deposition step and the dipping step for 3 times, then placing the mixture into a horizontal heat treatment furnace, heating to 1400 ℃ at the speed of 4 ℃/min under the argon atmosphere, preserving the heat for 3 hours, cooling to room temperature, and then taking out.

Example 2

Cutting the low density C/C composite material into phi 28 x 10mm³The cylinder is cleaned by ultrasonic cleaning for later use. Sequentially mixing ethyl orthosilicate, absolute ethyl alcohol and deionized water according to the weight ratio of about 9: 3: 1, regulating the pH value to 5 by using hydrochloric acid, and stirring for 2 hours at 70 ℃ to obtain silica sol. And (3) placing the low-density C/C composite material into silica sol for natural immersion for 7 days, drying, and depositing pyrolytic carbon for 3 hours by a chemical vapor infiltration method. And finally, preserving the heat for 2h at 1500 ℃ in a heat treatment furnace, cooling to the normal temperature, and then putting into ZrC precursor impregnation liquid. Impregnating solution of a ZrC precursor is prepared by mixing xylene and the ZrC precursor in a ratio of 2: 4, performing ultrasonic treatment for half an hour, and then putting the mixture into a magnetic stirrer to stir for more than 1 hour to prepare the product. And then putting the beaker filled with the sample and ZrC precursor impregnation liquid into a vacuum impregnation box, vacuumizing to-0.08 MPa, keeping for 0.5h, taking out, and putting into a drying box to dry for 2 days at 80 ℃. And repeating the impregnation step for 9 times, then placing the mixture into a chemical vapor infiltration furnace, raising the temperature to 1200 ℃ at 4 ℃/min under the protection of argon (100mL/min), introducing methyl trichlorosilane (1g/min) and hydrogen (100mL/min), keeping the temperature for 2 hours, closing a methyl trichlorosilane and hydrogen gas valve, cooling to room temperature, and taking out. Repeated depositionAnd 3 times of the steps and the dipping step, putting the mixture into a horizontal heat treatment furnace, heating to 1500 ℃ at the speed of 4 ℃/min under the argon atmosphere, preserving the heat for 2 hours, cooling to room temperature, and taking out.

Example 3

Cutting the low density C/C composite material into phi 28 x 10mm³The cylinder is cleaned by ultrasonic cleaning for later use. Sequentially mixing ethyl orthosilicate, absolute ethyl alcohol and deionized water according to the weight ratio of about 5: 4: 1, regulating the pH value to 3 by using hydrochloric acid, and stirring for 2 hours at 70 ℃ to obtain silica sol. And (3) placing the low-density C/C composite material into silica sol for natural immersion for 14 days, drying, and depositing pyrolytic carbon for 3 hours by a chemical vapor infiltration method. And finally, preserving the heat for 2h at 1600 ℃ in a heat treatment furnace, cooling to the normal temperature, and then putting into ZrC precursor impregnation liquid. Impregnating solution of a ZrC precursor is prepared by mixing xylene and the ZrC precursor in a ratio of 2: 4, performing ultrasonic treatment for half an hour, and then putting the mixture into a magnetic stirrer to stir for more than 1 hour to prepare the product. And then putting the beaker filled with the sample and ZrC precursor impregnation liquid into a vacuum impregnation box, vacuumizing to-0.08 MPa, keeping for 0.5h, taking out, and putting into a drying box to dry for 2 days at 80 ℃. And repeating the impregnation step for 9 times, then placing the mixture into a chemical vapor infiltration furnace, raising the temperature to 1100 ℃ at 4 ℃/min under the protection of argon (100mL/min), introducing methyl trichlorosilane (1g/min) and hydrogen (100mL/min), keeping the temperature for 2 hours, closing a methyl trichlorosilane and hydrogen gas valve, cooling to room temperature, and taking out. And repeating the deposition step and the dipping step for 3 times, then placing the mixture into a horizontal heat treatment furnace, heating to 1600 ℃ at the speed of 4 ℃/min under the argon atmosphere, preserving the heat for 2h, cooling to room temperature, and then taking out.