Preparation method of carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite material

Abstract

The present invention provides a preparation method of a carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite material, belonging to the technical field of ceramic composite materials; the preparation method includes steps of carbon fiber treatment, preparation of a hafnium carbide precursor solution, compounding, mixing, and forming and sintering; the step of preparing the hafnium carbide precursor solution is to add hafnium tetrachloride and citric acid into ethylene glycol monomethyl ether, stir at 58-63 °C for 2.0-2.5 h, then under a nitrogen atmosphere, lower the temperature to 47-52 °C, add ethylenediamine and triethanolamine, and react for 3.7-4.2 h to obtain the hafnium carbide precursor solution; the product prepared by the method of the present invention has good strength and toughness, excellent high-temperature stability performance, and good ablation resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic composite materials, and in particular relates to a method for preparing a carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite material. Background Art

[0002] Hafnium carbide is a compound composed of hafnium (Hf) and carbon (C). From the basic properties, hafnium carbide has an extremely high melting point of about 3890°C, making it one of the compounds with the highest known melting points. It also has a high hardness, which gives it good wear resistance and allows it to withstand harsh friction environments. It also has excellent chemical stability and can maintain its structure and stability in a variety of chemical environments. It also has excellent antioxidant properties in high-temperature environments and can effectively resist oxygen erosion. In the field of ceramics, hafnium carbide plays a vital role. Due to its ultra-high melting point and good high-temperature stability, hafnium carbide is often used to prepare ultra-high temperature ceramic materials and is widely used in extreme high-temperature environments such as aerospace and the nuclear industry.

[0003] However, hafnium carbide-based ceramic materials have some inherent defects, such as high brittleness and easy fracture; insufficient ablation resistance and easy fracture when subjected to external impact or thermal stress, which limits their use in complex environments such as high temperature and high speed.

[0004] Carbon fiber has the advantages of high strength, high modulus, low density and good thermal stability. The high strength of carbon fiber makes it difficult to break when subjected to large external forces, and can provide a strong bearing capacity for the hafnium carbide ceramic matrix. Its high modulus makes the carbon fiber less deformed when subjected to force, effectively enhancing the stability of the ceramic material. In addition, the addition of carbon fiber can effectively improve the brittleness of the hafnium carbide ceramic matrix. When the material is impacted by external forces, the carbon fiber will change the expansion direction during the crack expansion process, increase the tortuosity of the crack expansion path, absorb more energy, and thus improve the toughness of the composite material, better play the strengthening and toughening properties of carbon fiber in the hafnium carbide ceramic matrix, and at the same time improve the anti-ablation performance of the composite material.

[0005] However, the use of carbon fiber as a reinforcement phase in hafnium carbide-based ultra-high temperature ceramic composites has the following problems:

[0006] First, the interfacial bonding force between the carbon fiber and the hafnium carbide matrix is weak, resulting in low stress transfer efficiency. During the stress process, the carbon fiber is easily pulled out of the hafnium carbide matrix and cannot fully exert its reinforcing effect.

[0007] Second, the dispersion performance of carbon fiber is poor and the agglomeration is strong, which leads to poor homogeneity of the composite material. Stress concentration points are easily formed at the agglomeration of carbon fiber, which reduces the comprehensive performance of the composite material.

[0008] Thirdly, the preparation process of the prior art is relatively complex and costly, making it difficult to achieve large-scale industrial production. Summary of the Invention

[0009] In order to solve the technical problems existing in the prior art, the present invention provides a preparation method of a carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite material, which has high toughness and mechanical strength, excellent ablation resistance, and good high-temperature stability.

[0010] A preparation method of a carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite material includes carbon fiber treatment, preparation of a hafnium carbide precursor solution, compounding, mixing, and forming and sintering steps, which are specifically as follows:

[0011] 1. Carbon fiber treatment

[0012] (1) Pretreatment

[0013] Mix the carbon fiber evenly with 4 - 7 times its mass of acetone, carry out a water bath reflux reaction at a reaction temperature of 70 - 75°C for a reaction time of 7.8 - 8.3 h. After the reflux reaction ends, perform centrifugal washing and drying to obtain pretreated carbon fiber;

[0014] The length of the carbon fiber is 1.7 - 2.2 mm, and the diameter is 110 - 130 nm;

[0015] (2) Reprocessing

[0016] Put the pretreated carbon fiber into an ethanol solution, heat it to 62 - 66°C at a rate of 0.7 - 1.2°C / min, then slowly add the reprocessing solution, control the addition rate to be 0.42 - 0.54 g / min, stir while adding, with a stirring speed of 140 - 180 rpm. After the stirring ends, keep the temperature for a reaction of 3.8 - 4.2 h, and after filtration, washing, and drying, obtain reprocessed carbon fiber;

[0017] The mass ratio of the pretreated carbon fiber, ethanol solution, and reprocessing solution is 8.2 - 8.8:85 - 95:20 - 25;

[0018] The mass concentration of the ethanol solution is 40 - 44%;

[0019] The preparation method of the reprocessing solution is as follows: Add pyromellitic dianhydride to N,N-dimethylformamide, stir evenly, then add KH792 and a chitosan solution, and perform ultrasonic dispersion for 20 - 30 min with an ultrasonic power of 65 - 70 W and an ultrasonic frequency of 12 - 17 kHz. After the ultrasonic dispersion ends, obtain the reprocessing solution;

[0020] The chitosan solution is a mixed solution of chitosan and a 4.8 - 5.2 wt% acetic acid solution, and the mass ratio of chitosan to the 4.8 - 5.2 wt% acetic acid solution is 1.2 - 1.4:10.5 - 11.0;

[0021] The mass ratio of N,N - dimethylformamide, pyromellitic dianhydride, KH792 to the chitosan solution is 46 - 55:2.4 - 2.6:1.0 - 1.3:11.5 - 12.5.

[0022] 2. Preparation of hafnium carbide precursor solution

[0023] Add hafnium tetrachloride and citric acid to ethylene glycol monomethyl ether, heat it to 58 - 63 °C at a rate of 1.5 - 2.5 °C / min, keep stirring for 2.0 - 2.5 h, then under a nitrogen atmosphere, lower the temperature to 47 - 52 °C, add ethylenediamine and triethanolamine. After the addition, keep the reaction at 48 - 52 °C for 3.7 - 4.2 h to obtain the hafnium carbide precursor solution;

[0024] The volume - mass ratio of ethylene glycol monomethyl ether, hafnium tetrachloride, citric acid, ethylenediamine and triethanolamine is 450 - 550 mL:12.0 - 12.8 g:13.6 - 14.5 g:0.6 - 1.0 g:0.6 - 0.8 g.

[0025] 3. Composite

[0026] Place the re - processed carbon fiber in an ethanol solution, after dispersing it evenly, add the hafnium carbide precursor solution, and perform ultrasonic dispersion. The ultrasonic time is 37 - 42 min, the ultrasonic power is 245 - 255 W, and the ultrasonic frequency is 26 - 33 kHz. After the ultrasonic treatment, raise the temperature to 68 - 72 °C, and under a nitrogen atmosphere, keep the reaction for 7.8 - 8.3 h to obtain the carbon fiber / hafnium carbide composite;

[0027] The mass ratio of the re - processed carbon fiber, ethanol solution, and hafnium carbide precursor solution is 1.0 - 1.5 g:36 - 43 g:780 - 820 mL;

[0028] The mass concentration of the ethanol solution is 48 - 52%.

[0029] 4. Mixing

[0030] Disperse the carbon fiber / hafnium carbide composite, hafnium boride, modified alumina, and sodium carboxymethylcellulose in deionized water, raise the temperature to 50 - 55 °C, keep stirring for 57 - 65 min, and after filtration, washing and drying, obtain the mixed material;

[0031] The mass ratio of the carbon fiber / hafnium carbide composite, hafnium boride, modified alumina, sodium carboxymethyl cellulose and deionized water is 100:8.0 - 8.5:1.8 - 2.2:1.0 - 1.6:480 - 520;

[0032] The preparation method of the modified alumina is as follows: polyvinyl butyral is added to an ethanol solution, the temperature is raised to 52 - 56 °C, and it is stirred at 320 - 340 rpm for 38 - 43 min to obtain an impregnating solution; alumina powder is put into the impregnating solution, and it is kept at 38 - 42 °C for heat preservation and impregnation for 1.8 - 2.2 h. After the impregnation is completed, it is filtered, washed and dried to obtain the modified alumina;

[0033] The particle size of the alumina powder is 110 - 130 nm;

[0034] The mass ratio of the ethanol solution to polyvinyl butyral is 100:4.2 - 4.8;

[0035] The mass concentration of the ethanol solution is 30 - 34%;

[0036] The mass ratio of the alumina powder to the impregnating solution is 1:6 - 8.

[0037] 5. Molding and sintering

[0038] The mixture is formed into a green body, and the green body is placed in an argon atmosphere. It is heated at a rate of 5.0 - 7.0 °C / min to 580 - 620 °C, kept warm for 18 - 23 min, and then heated at a rate of 1.5 - 2.5 °C / min to 1460 - 1520 °C, and kept warm for 2.8 - 3.5 h to obtain a carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite.

[0039] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0040] 1. The present invention uses carbon fiber as the reinforcing phase and hafnium carbide as the ceramic matrix for preparing ultra-high temperature ceramic composites. The carbon fiber is treated twice. First, it is pretreated to remove components such as oil stains and impurities on the surface of the carbon fiber. In the reprocessing step, the reprocessing solution is prepared by treating KH792 and chitosan with pyromellitic dianhydride. Pyromellitic dianhydride can undergo amidation reactions with the amino groups of KH792 and chitosan, and an imine ring structure will be formed through dehydration reactions during the amidation reactions. Moreover, chitosan can improve the dispersibility and stability of the carbon fiber. Then, a hafnium carbide precursor solution containing amino groups is prepared by a specific method. In the composite step, the imine ring of the carbon fiber can combine with the hafnium carbide precursor, enabling the carbon fiber and hafnium carbide to be tightly and firmly bonded together, enhancing their interfacial compatibility and bonding uniformity, better exerting the reinforcing performance of the carbon fiber, effectively transmitting stress, and improving the strength, toughness, and stability of the composite material. In the mixing step, alumina is treated with polyvinyl butyral, which can reduce the surface energy of alumina particles, reduce the agglomeration between particles. The modified alumina obtained after treatment can combine with the carbon fiber / hafnium carbide composite, improving the dispersion uniformity and homogeneity of the mixture, thus ensuring the strength uniformity and high-temperature resistance of the composite material and improving the comprehensive performance of the composite material.

[0041] 2. The carbon fiber-reinforced hafnium carbide-based ultra-high temperature ceramic composite material prepared by the method of the present invention has a flexural strength of 854 - 875 MPa and a fracture toughness of 11.5 - 11.8 MPa·m at room temperature. 1 / 2 After standing at 2200 °C for 120 h, the flexural strength is 796 - 834 MPa and the fracture toughness is 10.8 - 11.2 MPa·m. 1 / 2 ;

[0042] 3. The carbon fiber-reinforced hafnium carbide-based ultra-high temperature ceramic composite material prepared by the method of the present invention has a mass ablation rate of -0.09 to -0.05 mg / s under ablation at 2500 °C by a hydrogen-oxygen flame for 5 min. Detailed Embodiments

[0043] For a clearer understanding of the technical features, objectives, and effects of the present invention, the detailed embodiments of the present invention are now described.

[0044] Example 1

[0045] 1. Carbon Fiber Treatment

[0046] (1) Pretreatment

[0047] The carbon fiber is mixed evenly with acetone with a mass 4 times that of the carbon fiber, and a water bath reflux reaction is carried out. The reaction temperature is 70 °C and the reaction time is 7.8 h. After the reflux reaction ends, it is centrifuged, washed, and dried to obtain pretreated carbon fiber.

[0048] The length of the carbon fiber is 1.7 mm and the diameter is 110 nm;

[0049] (2)Reprocessing

[0050] Put 8.2 g of pretreated carbon fiber into 85 g of 40 wt% ethanol solution, heat it to 62 °C at a rate of 0.7 °C / min, then slowly add 20 g of reprocessing solution, control the addition rate to be 0.42 g / min, stir while adding, the stirring speed is 140 rpm. After stirring ends, keep the temperature for reaction for 3.8 h, filter, wash and dry to obtain reprocessed carbon fiber;

[0051] The preparation method of the reprocessing solution is as follows: add 2.4 g of pyromellitic dianhydride to 46 g of N,N-dimethylformamide, stir evenly, then add 1.0 g of KH792 and 11.5 g of chitosan solution, carry out ultrasonic dispersion, the ultrasonic time is 20 min, the ultrasonic power is 65 W, the ultrasonic frequency is 12 kHz. After ultrasonic dispersion ends, obtain the reprocessing solution;

[0052] The chitosan solution is a mixed solution of chitosan and 4.8 wt% acetic acid solution, and the mass ratio of chitosan to 4.8 wt% acetic acid solution is 1.2:10.5.

[0053] 2. Prepare hafnium carbide precursor solution

[0054] Add 12.0 g of hafnium tetrachloride and 13.6 g of citric acid to 450 mL of ethylene glycol monomethyl ether, heat it to 58 °C at a rate of 1.5 °C / min, keep the temperature and stir for 2.0 h, then under a nitrogen atmosphere, lower the temperature to 47 °C, add 0.6 g of ethylenediamine and 0.6 g of triethanolamine. After adding is completed, keep the temperature for reaction at 48 °C for 4.2 h to obtain hafnium carbide precursor solution.

[0055] 3. Composite

[0056] Put 1.0 g of reprocessed carbon fiber into 36 g of 48 wt% ethanol solution, disperse evenly, then add 780 mL of hafnium carbide precursor solution, carry out ultrasonic dispersion, the ultrasonic time is 37 min, the ultrasonic power is 245 W, the ultrasonic frequency is 26 kHz. After ultrasonic treatment ends, raise the temperature to 68 °C, and keep the temperature for reaction for 7.8 h under a nitrogen atmosphere to obtain carbon fiber / hafnium carbide composite.

[0057] 4. Mixing

[0058] Disperse 100 g of carbon fiber / hafnium carbide composite, 8.0 g of hafnium boride, 1.8 g of modified alumina, and 1.0 g of sodium carboxymethyl cellulose in 480 g of deionized water. Raise the temperature to 50 °C and stir for 65 min while maintaining the temperature. After filtration, washing, and drying, a mixed material is obtained;

[0059] The preparation method of the modified alumina is as follows: Add 4.2 g of polyvinyl butyral to 100 g of 30 wt% ethanol solution, raise the temperature to 52 °C, and stir at 320 rpm for 38 min to obtain an impregnating solution; Put alumina powder into 6 times the mass of the impregnating solution, keep the temperature at 38 °C for impregnation for 1.8 h. After the impregnation is completed, filter, wash, and dry to obtain modified alumina;

[0060] The particle size of the alumina powder is 110 nm.

[0061] 5. Molding and sintering

[0062] Form the mixed material into a green body, place the green body in an argon atmosphere, heat it to 580 °C at a rate of 5.0 °C / min, hold for 18 min, then heat it to 1460 °C at a rate of 1.5 °C / min, and hold for 3.5 h to obtain a carbon fiber-reinforced hafnium carbide-based ultra-high temperature ceramic composite.

[0063] Example 2

[0064] 1. Carbon fiber treatment

[0065] (1)Pretreatment

[0066] Mix carbon fiber evenly with 7 times its mass of acetone, carry out a water bath reflux reaction, the reaction temperature is 75 °C, the reaction time is 8.3 h. After the reflux reaction is completed, centrifuge, wash, and dry to obtain pretreated carbon fiber;

[0067] The length of the carbon fiber is 2.2 mm and the diameter is 130 nm;

[0068] (2)Reprocessing

[0069] Put 8.8 g of pretreated carbon fiber into 95 g of 44 wt% ethanol solution, heat it to 66 °C at a rate of 1.2 °C / min, then slowly add 25 g of reprocessing solution, control the addition rate to be 0.54 g / min, stir while adding, the stirring speed is 180 rpm. After the stirring is completed, keep the temperature for reaction for 4.2 h. After filtration, washing, and drying, obtain reprocessed carbon fiber;

[0070] The preparation method of the reprocessing liquid is as follows: add 2.6 g of pyromellitic dianhydride to 55 g of N,N-dimethylformamide, stir evenly, then add 1.3 g of KH792 and 12.5 g of chitosan solution, and perform ultrasonic dispersion. The ultrasonic time is 30 min, the ultrasonic power is 70 W, and the ultrasonic frequency is 17 kHz. After the ultrasonic dispersion is completed, the reprocessing liquid is obtained.

[0071] The chitosan solution is a mixed solution of chitosan and 5.2 wt% acetic acid solution, and the mass ratio of chitosan to 5.2 wt% acetic acid solution is 1.4:11.0.

[0072] 2. Preparation of hafnium carbide precursor solution

[0073] Add 12.8 g of hafnium tetrachloride and 14.5 g of citric acid to 550 mL of ethylene glycol monomethyl ether, heat up to 63 °C at a rate of 2.5 °C / min, keep warm and stir for 2.5 h, then under a nitrogen atmosphere, lower the temperature to 52 °C, add 1.0 g of ethylenediamine and 0.8 g of triethanolamine. After the addition is completed, keep warm and react at 52 °C for 3.7 h to obtain the hafnium carbide precursor solution.

[0074] 3. Composite

[0075] Put 1.5 g of reprocessed carbon fiber into 43 g of 52 wt% ethanol solution, disperse evenly, then add 820 mL of hafnium carbide precursor solution, and perform ultrasonic dispersion. The ultrasonic time is 42 min, the ultrasonic power is 255 W, and the ultrasonic frequency is 33 kHz. After the ultrasonic treatment is completed, raise the temperature to 72 °C, and keep warm and react for 8.3 h under a nitrogen atmosphere to obtain the carbon fiber / hafnium carbide composite.

[0076] 4. Mixing

[0077] Disperse 100 g of carbon fiber / hafnium carbide composite, 8.5 g of hafnium boride, 2.2 g of modified alumina, and 1.6 g of sodium carboxymethylcellulose in 520 g of deionized water, raise the temperature to 55 °C, keep warm and stir for 57 min, and obtain the mixed material after filtration, washing, and drying.

[0078] The preparation method of the modified alumina is as follows: add 4.8 g of polyvinyl butyral to 100 g of 34 wt% ethanol solution, raise the temperature to 56 °C, and stir at 340 rpm for 43 min to obtain the impregnating solution; put the alumina powder into 8 times the mass of the impregnating solution, keep warm and impregnate at 42 °C for 2.2 h. After the impregnation is completed, obtain the modified alumina after filtration, washing, and drying.

[0079] The particle size of the alumina powder is 130 nm.

[0080] 5. Molding and sintering

[0081] The mixture is formed into a green body, and the green body is placed in an argon atmosphere. It is heated to 620 °C at a rate of 7.0 °C / min, held for 23 min, and then heated to 1520 °C at a rate of 2.5 °C / min and held for 2.8 h to obtain a carbon fiber reinforced hafnium carbide based ultra-high temperature ceramic composite.

[0082] Example 3

[0083] 1. Carbon fiber treatment

[0084] (1)Pretreatment

[0085] The carbon fiber is mixed evenly with 5 times its mass of acetone, and a water bath reflux reaction is carried out. The reaction temperature is 73 °C and the reaction time is 8.0 h. After the reflux reaction ends, it is centrifuged, washed and dried to obtain pretreated carbon fiber;

[0086] The length of the carbon fiber is 2.0 mm and the diameter is 120 nm;

[0087] (2)Reprocessing

[0088] 8.5 g of pretreated carbon fiber is put into 90 g of a 42 wt% ethanol solution, heated to 64 °C at a rate of 1.0 °C / min, and then 23 g of the reprocessing solution is slowly added, controlling the addition rate to be 0.50 g / min. Stirring is carried out during the addition, and the stirring speed is 160 rpm. After the stirring ends, it is held for reaction for 4.0 h, and after filtration, washing and drying, reprocessed carbon fiber is obtained;

[0089] The preparation method of the reprocessing solution is as follows: 2.5 g of pyromellitic dianhydride is added to 50 g of N,N-dimethylformamide, stirred evenly, then 1.2 g of KH792 and 12.0 g of chitosan solution are added, and ultrasonic dispersion is carried out. The ultrasonic time is 25 min, the ultrasonic power is 68 W, and the ultrasonic frequency is 15 kHz. After the ultrasonic dispersion ends, the reprocessing solution is obtained;

[0090] The chitosan solution is a mixed solution of chitosan and a 5.0 wt% acetic acid solution, and the mass ratio of chitosan to the 5.0 wt% acetic acid solution is 1.3:10.7.

[0091] 2. Preparation of hafnium carbide precursor solution

[0092] 12.4 g of hafnium tetrachloride and 14.1 g of citric acid are added to 500 mL of ethylene glycol monomethyl ether, heated to 60 °C at a rate of 2.0 °C / min, held for stirring for 2.3 h, and then under a nitrogen atmosphere, the temperature is lowered to 50 °C, 0.8 g of ethylenediamine and 0.7 g of triethanolamine are added. After the addition is completed, it is held for reaction at 50 °C for 4.0 h to obtain a hafnium carbide precursor solution.

[0093] 3. Composite

[0094] Disperse 1.2 g of reprocessed carbon fiber in 40 g of 50 wt% ethanol solution. After uniform dispersion, add 800 mL of hafnium carbide precursor solution, and perform ultrasonic dispersion. The ultrasonic time is 40 min, the ultrasonic power is 250 W, and the ultrasonic frequency is 30 kHz. After the ultrasonic treatment, raise the temperature to 70 °C, and carry out a heat preservation reaction for 8.0 h under a nitrogen atmosphere to obtain a carbon fiber / hafnium carbide composite.

[0095] 4. Mixing

[0096] Disperse 100 g of carbon fiber / hafnium carbide composite, 8.3 g of hafnium boride, 2.0 g of modified alumina, and 1.3 g of sodium carboxymethyl cellulose in 500 g of deionized water. Raise the temperature to 52 °C, and carry out heat preservation stirring for 60 min. After filtration, washing, and drying, obtain a mixed material;

[0097] The preparation method of the modified alumina is as follows: add 4.5 g of polyvinyl butyral to 100 g of 32 wt% ethanol solution, raise the temperature to 54 °C, and stir at 330 rpm for 40 min to obtain an impregnating solution; put alumina powder into 7 times the mass of the impregnating solution, carry out heat preservation impregnation at 40 °C for 2.0 h. After the impregnation, obtain the modified alumina through filtration, washing, and drying;

[0098] The particle size of the alumina powder is 120 nm.

[0099] 5. Molding and sintering

[0100] Form the mixed material into a green body, place the green body in an argon atmosphere, raise the temperature to 600 °C at a rate of 6.0 °C / min, hold for 20 min, and then raise the temperature to 1500 °C at a rate of 2.0 °C / min, and hold for 3.0 h to obtain a carbon fiber-reinforced hafnium carbide-based ultra-high temperature ceramic composite.

[0101] Comparative Example 1

[0102] On the basis of Example 3, make the following changes:

[0103] In the reprocessing step of carbon fiber treatment, the preparation method of the reprocessing solution is as follows: add 1.2 g of KH792 to 50 g of N,N-dimethylformamide, perform ultrasonic dispersion, the ultrasonic time is 25 min, the ultrasonic power is 68 W, and the ultrasonic frequency is 15 kHz. After the ultrasonic dispersion, obtain the reprocessing solution;

[0104] The pretreatment step of carbon fiber treatment, the step of preparing hafnium carbide precursor solution, the compounding, mixing, and molding and sintering steps are exactly the same as those in Example 3.

[0105] Comparative Example 2

[0106] Based on Example 3, the following changes are made:

[0107] The step of preparing the hafnium carbide precursor solution is to place 12.4 g of hafnium carbide powder in 40 g of a 50 wt% ethanol solution, stir evenly to obtain the hafnium carbide precursor solution; the particle size of the hafnium carbide powder is 150 nm;

[0108] In the mixing step, the modified alumina is replaced with alumina powder without any treatment, and the particle size of the alumina powder is 120 nm;

[0109] The steps of carbon fiber treatment, compounding, and forming and sintering are exactly the same as those in Example 3.

[0110] Performance testing

[0111] Test the comprehensive performance of the products obtained in Examples 1-3 and Comparative Examples 1-2, specifically as follows:

[0112]

[0113] Among them, the test method for the high and low temperature cycle resistance performance is to heat the product to 2500 °C at a rate of 50 °C / min, hold for 12.0 h, and then cool it to room temperature at a rate of 60 °C / min; the above operation is one cycle, and after 10 cycles, the fracture toughness and flexural strength are tested again.

[0114] The present invention uses carbon fiber as the reinforcing phase and hafnium carbide as the ceramic matrix to prepare ultra-high temperature ceramic composites; the carbon fiber is treated twice. First, it is pretreated to remove components such as oil and impurities on the surface of the carbon fiber; in the reprocessing step, the reprocessing liquid is prepared by treating KH792 and chitosan with pyromellitic dianhydride. Pyromellitic dianhydride can undergo an amidation reaction with the amino groups of KH792 and chitosan, and an imine ring structure will be formed during the amidation reaction through dehydration reaction, and chitosan can improve the dispersibility and stability of the carbon fiber; then a specific method is used to prepare a hafnium carbide precursor solution containing amino groups; in the compounding step, the imine ring of the carbon fiber can combine with the hafnium carbide precursor, so that the carbon fiber and hafnium carbide are tightly and firmly combined together, enhancing their interfacial compatibility and binding uniformity, better exerting the reinforcing performance of the carbon fiber, effectively transmitting stress, and improving the strength, toughness, and stability of the composite material; in the mixing step, the alumina is treated with polyvinyl butyral, which can reduce the surface energy of the alumina particles, reduce the agglomeration between particles, and the modified alumina obtained after treatment can combine with the carbon fiber / hafnium carbide composite, improving the dispersion uniformity and homogeneity of the mixture, thus ensuring the strength uniformity and high temperature resistance of the composite material and improving the comprehensive performance of the composite material.

[0115] Comparative Example 1 only uses KH792 to reprocess carbon fibers. Although it can modify the carbon fibers, its function is relatively single, omitting the cross-linking effect of pyromellitic dianhydride and the protective effect of chitosan. This will not only reduce the stability of the carbon fibers, but also weaken the interfacial bonding with hafnium carbide, ultimately reducing the strength and toughness of the product, and also weakening the high-temperature resistance to a certain extent; Comparative Example 2 directly mixes hafnium carbide powder with reprocessed fibers, and its interfacial compatibility with carbon fibers is poor, and the bonding force is weak. Moreover, in the mixing step, alumina is not modified, resulting in poor homogeneity of the mixture, and ultimately leading to poor structure and uniformity of the composite material. When the material is subjected to external forces, high temperatures and other conditions, cracks, damage and other situations are likely to occur, reducing the strength, toughness, high-temperature resistance and ablation resistance of the material.

[0116] Unless otherwise specified, the percentages used in the present invention are all mass percentages.

[0117] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite material, characterized in that, It includes steps of carbon fiber treatment, preparation of hafnium carbide precursor solution, compounding, mixing, and forming and sintering; The carbon fiber treatment includes a pretreatment step and a re-treatment step; The re-treatment step is to put the pretreated carbon fiber into an ethanol solution, heat it up to 62 - 66 °C, add the re-treatment liquid, keep it warm and react for 3.8 - 4.2 h to obtain the re-treated carbon fiber; The preparation method of the re-treatment liquid is to add pyromellitic dianhydride to N,N-dimethylformamide, stir evenly, then add KH792 and chitosan solution, and perform ultrasonic dispersion to obtain the re-treatment liquid; The step of preparing the hafnium carbide precursor solution is to add hafnium tetrachloride and citric acid to ethylene glycol monomethyl ether, stir at 58 - 63 °C for 2.0 - 2.5 h, then under a nitrogen atmosphere, lower the temperature to 47 - 52 °C, add ethylenediamine and triethanolamine, and react for 3.7 - 4.2 h to obtain the hafnium carbide precursor solution; The compounding step is to put the re-treated carbon fiber into an ethanol solution, disperse it evenly, then add the hafnium carbide precursor solution, perform ultrasonic dispersion, the ultrasonic time is 37 - 42 min, the ultrasonic power is 245 - 255 W, the ultrasonic frequency is 26 - 33 kHz. After the ultrasonic treatment, raise the temperature to 68 - 72 °C, and keep it warm and react for 7.8 - 8.3 h under a nitrogen atmosphere to obtain the carbon fiber / hafnium carbide composite; The mixing step is to disperse the carbon fiber / hafnium carbide composite, hafnium boride, modified alumina, and sodium carboxymethylcellulose in deionized water, raise the temperature to 50 - 55 °C, keep it warm and stir for 57 - 65 min, and after filtration, washing, and drying, obtain the mixed material.

2. The preparation method of a carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite material according to claim 1, characterized in that, For the carbon fiber treatment, in the pretreatment step, mix the carbon fiber evenly with 4 - 7 times its mass of acetone, perform a water bath reflux reaction, the reaction temperature is 70 - 75 °C, the reaction time is 7.8 - 8.3 h. After the reflux reaction, perform centrifugation, washing, and drying to obtain the pretreated carbon fiber; The length of the carbon fiber is 1.7 - 2.2 mm, and the diameter is 110 - 130 nm.

3. The preparation method of a carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite material according to claim 1, characterized in that, For the carbon fiber treatment, in the re-treatment step, put the pretreated carbon fiber into an ethanol solution, heat it up to 62 - 66 °C at a rate of 0.7 - 1.2 °C / min, then slowly add the re-treatment liquid, control the addition rate to be 0.42 - 0.54 g / min, stir while adding, the stirring speed is 140 - 180 rpm. After the stirring ends, keep it warm and react for 3.8 - 4.2 h, and after filtration, washing, and drying, obtain the re-treated carbon fiber; The mass ratio of the pretreated carbon fiber, ethanol solution, and re-treatment liquid is 8.2 - 8.8:85 - 95:20 - 25; The mass concentration of the ethanol solution is 40 - 44%.

4. The preparation method of a carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite material according to claim 1, characterized in that, In the preparation method of the reprocessing solution, for the ultrasonic dispersion, the ultrasonic time is 20 - 30 min, the ultrasonic power is 65 - 70 W, and the ultrasonic frequency is 12 - 17 kHz; The chitosan solution is a mixed solution of chitosan and a 4.8 - 5.2 wt% acetic acid solution, and the mass ratio of chitosan to the 4.8 - 5.2 wt% acetic acid solution is 1.2 - 1.4:10.5 - 11.0; The mass ratio of N,N - dimethylformamide, pyromellitic dianhydride, KH792 and the chitosan solution is 46 - 55:2.4 - 2.6:1.0 - 1.3:11.5 - 12.

5.

5. The preparation method of a carbon fiber reinforced hafnium carbide - based ultra - high temperature ceramic composite material according to claim 1, characterized in that In the step of preparing the hafnium carbide precursor solution, the volume - mass ratio of ethylene glycol monomethyl ether, hafnium tetrachloride, citric acid, ethylenediamine and triethanolamine is 450 - 550 mL:12.0 - 12.8 g:13.6 - 14.5 g:0.6 - 1.0 g:0.6 - 0.8 g.

6. The preparation method of a carbon fiber reinforced hafnium carbide - based ultra - high temperature ceramic composite material according to claim 1, characterized in that In the composite step, the mass ratio of the re - processed carbon fiber, ethanol solution, and hafnium carbide precursor solution is 1.0 - 1.5 g:36 - 43 g:780 - 820 mL; The mass concentration of the ethanol solution is 48 - 52%.

7. The preparation method of a carbon fiber reinforced hafnium carbide - based ultra - high temperature ceramic composite material according to claim 1, characterized in that In the mixing step, the mass ratio of the carbon fiber / hafnium carbide composite, hafnium boride, modified alumina, sodium carboxymethylcellulose and deionized water is 100:8.0 - 8.5:1.8 - 2.2:1.0 - 1.6:480 - 520.

8. The preparation method of a carbon fiber reinforced hafnium carbide - based ultra - high temperature ceramic composite material according to claim 7, characterized in that The preparation method of the modified alumina is as follows: Add polyvinyl butyral to an ethanol solution, raise the temperature to 52 - 56 °C, stir at 320 - 340 rpm for 38 - 43 min to obtain an impregnating solution; Put alumina powder into the impregnating solution, keep it at 38 - 42 °C for heat - preservation impregnation for 1.8 - 2.2 h. After the impregnation is completed, filter, wash and dry to obtain the modified alumina; The particle size of the alumina powder is 110 - 130 nm; The mass ratio of the ethanol solution to polyvinyl butyral is 100:4.2 - 4.8; The mass concentration of the ethanol solution is 30 - 34%; The mass ratio of the alumina powder to the impregnating solution is 1:6 - 8.

9. The preparation method of a carbon fiber reinforced hafnium carbide - based ultra - high temperature ceramic composite material according to claim 1, characterized in that The forming and sintering step is as follows: the mixed material is formed into a green body, the green body is placed in an argon atmosphere, heated to 580 - 620 °C at a rate of 5.0 - 7.0 °C / min, held for 18 - 23 min, then heated to 1460 - 1520 °C at a rate of 1.5 - 2.5 °C / min, and held for 2.8 - 3.5 h to obtain a carbon fiber reinforced hafnium carbide-based ultra-high temperature ceramic composite material.

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