Preparation process of impact-resistant carbon fiber foam composite material

Abstract

The present invention discloses a preparation process of an impact-resistant carbon fiber foam composite material, which belongs to the field of foam composite materials. The preparation process comprises the following steps: pre-treating sedge grass to obtain a carbon precursor, mixing the carbon precursor, a connector and anhydrous ethanol to carry out a first impregnation reaction, adding modified carbon fiber and a first catalyst after the reaction to carry out a second impregnation reaction to obtain a precursor, and the precursor is subjected to a pyrolysis reaction to obtain the impact-resistant carbon fiber foam composite material. The introduction of Mg-MOF increases the porosity, while the cross-linked network of the connector and cellulose optimizes the pore distribution, making it more uniform. This optimized pore structure not only improves the energy absorption capacity of the composite material, but also reduces stress concentration; multiple effects work together to significantly enhance the interfacial bonding strength between the fiber and the matrix, so that the impact energy can be more evenly distributed throughout the material, thereby improving impact resistance.

Description

Technical Field

[0001] The invention relates to the field of foam composite materials, and in particular to a preparation process of an impact-resistant carbon fiber foam composite material. Background Art

[0002] Carbon fiber foam composites, as lightweight, high-strength, and versatile materials, have garnered widespread attention in engineering in recent years. Their unique pore structure not only effectively absorbs and disperses impact energy but also exhibits excellent thermal shock stability in high-temperature environments. However, conventional preparation methods often struggle to achieve both high impact resistance and an optimized pore structure, leading to numerous challenges in their practical application.

[0003] Although carbon fiber foam composites have significantly improved their impact resistance compared to traditional carbon fiber composites, the existing technology still has the following problems: First, the energy absorption mechanism is single. At present, the impact resistance of carbon fiber foam composites mainly relies on the plastic deformation and pore collapse of the foam structure to absorb energy, but under high-speed impact conditions, the energy absorption efficiency of this mechanism will drop significantly. Secondly, the interface bonding strength is low. The interface bonding strength between the carbon fiber and the foam matrix is ​​insufficient, and delamination failure is prone to occur during the impact process, reducing the overall performance of the material. In addition, the fiber arrangement and foam structure of traditional carbon fiber foam composites usually have obvious directionality, which leads to large differences in the impact resistance of the material in different directions, limiting its reliability in practical applications.

[0004] Porosity is a key structural parameter of carbon fiber foam composites, directly affecting the material's impact resistance, mechanical properties, and lightweighting. However, existing technologies have the following problems with porosity control: First, the porosity distribution is uneven. Traditional preparation methods make it difficult to precisely control the porosity distribution of the foam structure, resulting in localized high-density or low-density areas within the material, which may cause stress concentration and accelerate material failure. Second, the pore shape and size are difficult to control. Existing technologies generally have difficulty precisely controlling the shape and size of pores, resulting in a highly random pore structure and an inability to fully realize the energy absorption potential of the foam structure. Furthermore, it is difficult to achieve both high porosity and high strength. Increasing the porosity can enhance the material's energy absorption capacity, but at the same time it reduces the material's overall strength and stiffness. Existing technologies have significant deficiencies in this balance. Chinese invention patent CN105924207B discloses a method for preparing silicon carbide foam ceramics. The process is simple, the preparation cycle is short, and the porosity of the silicon carbide foam ceramics can be adjusted within a certain range. However, the application does not address the impact resistance of the silicon carbide foam ceramics.

[0005] Therefore, in order to overcome the deficiencies of the prior art in terms of impact resistance and porosity control, the present invention provides a process for preparing an impact-resistant carbon fiber foam composite material. Summary of the Invention

[0006] To solve the problems existing in the prior art, the present invention provides a process for preparing an impact-resistant carbon fiber foam composite material. Specifically, the technical solution of the present invention includes the following contents:

[0007] A process for preparing an impact-resistant carbon fiber foam composite material, the process comprising the following steps:

[0008] The acanthus sinensis is pretreated to obtain a carbon precursor, the carbon precursor, a connector and anhydrous ethanol are mixed to perform a first impregnation reaction, and after the reaction, modified carbon fiber and a first catalyst are added to perform a second impregnation reaction to obtain a precursor, and the precursor is subjected to a pyrolysis reaction to obtain the impact-resistant carbon fiber foam composite material.

[0009] Furthermore, the preparation method of the linker comprises the following steps:

[0010] Dicyandiamide, methylhydrogendichlorosilane and a second catalyst are dispersed in n-hexane, and stirred and reacted in an inert gas protection environment to prepare the linker.

[0011] Furthermore, the preparation method of the modified carbon fiber comprises the following steps:

[0012] The chopped carbon fibers are sequentially desized and oxidized to obtain oxidized carbon fibers. Magnesium nitrate hexahydrate, 2-aminoterephthalic acid and a mixed solvent are mixed to obtain a mixture. The oxidized carbon fibers are dispersed in the mixture and subjected to solvent thermal reaction to obtain the modified carbon fibers.

[0013] Furthermore, the weight ratio of the dicyandiamide, methylhydrogendichlorosilane and the second catalyst is 45-60:20-25:10-15.

[0014] Furthermore, the second catalyst is triethylamine.

[0015] Furthermore, the stirring reaction includes a reaction temperature of 5-15° C. and a reaction time of 3-4 h.

[0016] Furthermore, the desizing treatment is to perform ultrasonic treatment in acetone for 10 to 20 minutes and then keep the mixture at 80 to 85° C. for 8 to 10 hours.

[0017] Furthermore, the oxidation treatment is carried out in 65% concentrated nitric acid at 60-70° C. for 2-3 hours.

[0018] Furthermore, the weight ratio of the magnesium nitrate hexahydrate to 2-aminoterephthalic acid is 10-15:2-3.

[0019] Furthermore, the mixed solvent is prepared by N,N-dimethylformamide, anhydrous ethanol and deionized water in a volume ratio of 15:1:1.

[0020] Furthermore, the weight ratio of the magnesium nitrate hexahydrate to the oxidized carbon fiber is 10-15:5-8.

[0021] Furthermore, the thermal reaction includes a reaction temperature of 120-125° C. and a reaction time of 20-24 h.

[0022] Furthermore, the weight ratio of the carbon precursor, the connector and the modified carbon fiber is 10-15:15-30:1-2.

[0023] Furthermore, the first impregnation reaction includes a reaction temperature of 60-70° C. and a reaction time of 12-24 hours.

[0024] Furthermore, the weight ratio of the modified carbon fiber to the first catalyst is 1-2:0.15-0.25.

[0025] Furthermore, the first catalyst is scandium trifluoromethanesulfonate.

[0026] Furthermore, the second impregnation reaction includes a reaction temperature of 25-30° C. and a reaction time of 4-6 hours.

[0027] Furthermore, the inert gas is nitrogen.

[0028] Furthermore, the pyrolysis reaction includes a reaction temperature of 1000-1500° C. and a reaction time of 3-4 hours.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] (1) The present invention grafts dicyandiamide onto methylhydrogen dichlorosilane through an aminolysis reaction to obtain a connector, desizing and oxidizing short carbon fibers to obtain oxidized carbon fibers, using 2-aminoterephthalic acid as an organic ligand, Mg in magnesium nitrate hexahydrate, 2+ As an open metal site, Mg-MOF is synthesized on the surface of oxidized carbon fiber to obtain modified carbon fiber; the carbon precursor, the product after heat treatment of dragon beard grass, is used as the carbon skeleton, and the amino group and silicon-hydrogen bond in the connector cooperates with the hydrogen bond to form a stable three-dimensional cross-linked network with the cellulose in the dragon beard grass. The amino group in the modified carbon fiber undergoes a transamination reaction with the C=N in the connector, and the modified carbon fiber is connected to the three-dimensional cross-linked network. After a pyrolysis reaction, an impact-resistant carbon fiber foam composite material is obtained.

[0031] (2) The present invention grafts dicyandiamide onto methylhydrogendichlorosilane through an aminolysis reaction to form a linker with amino groups and silicon-hydrogen bonds. These functional groups form hydrogen bonds with the hydroxyl groups in the cellulose of the sedge grass to construct a stable three-dimensional cross-linked network. The amino groups in the modified carbon fiber undergo a transamination reaction with the C=N in the linker, firmly connecting the modified carbon fiber to the three-dimensional cross-linked network. The introduction of Mg-MOF increases the porosity, while the cross-linked network of the linker and cellulose optimizes the pore distribution and makes it more uniform. This optimized pore structure not only improves the energy absorption capacity of the composite material, but also reduces stress concentration. The above multiple effects synergistically enhance the interfacial bonding strength between the fiber and the matrix, so that the impact energy can be more evenly distributed throughout the composite material, thereby improving the impact resistance.

[0032] (3) The porous structure of Mg-MOF increases the porosity and pore connectivity of the carbon fiber foam composite material, thereby reducing the concentration of thermal stress and improving the thermal shock stability of the composite material; the connection of the modified carbon fiber enhances the interfacial bonding strength between the fiber and the matrix, so that the material can better resist the interfacial peeling caused by thermal stress during the thermal shock process; in addition, the pyrolysis reaction not only removes organic impurities, but also further optimizes the pore structure of the composite material through high-temperature treatment, so that it exhibits excellent thermal shock stability in a high-temperature environment. This multi-faceted synergistic effect enables the composite material to better disperse stress and reduce stress concentration during the thermal shock process, thereby significantly improving its thermal shock resistance.

[0033] (4) The present invention uses the herbaceous grass as raw material, which is low-cost and reduces the burning or accumulation of agricultural waste, thereby reducing pollution to the environment. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions of the present invention through the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.

[0036] Preparation Example 1:

[0037] The preparation of the linker comprises the following steps:

[0038] 45 parts by weight of dicyandiamide, 20 parts by weight of methylhydrogendichlorosilane and 10 parts by weight of triethylamine were dispersed in 500 parts by weight of n-hexane, and stirred at 5° C. for 3 hours in a nitrogen atmosphere. After the reaction was completed, the mixture was filtered and rotary evaporated to obtain a linker.

[0039] Preparation Example 2:

[0040] The preparation of the linker comprises the following steps:

[0041] 50 parts by weight of dicyandiamide, 21 parts by weight of methylhydrogendichlorosilane and 12 parts by weight of triethylamine were dispersed in 500 parts by weight of n-hexane, and stirred at 8° C. for 3.2 hours in a nitrogen atmosphere. After the reaction was completed, the linker was filtered and evaporated.

[0042] Preparation Example 3:

[0043] The preparation of the linker comprises the following steps:

[0044] 55 parts by weight of dicyandiamide, 23 parts by weight of methylhydrodichlorosilane and 13 parts by weight of triethylamine were dispersed in 500 parts by weight of n-hexane, and stirred at 10° C. for 3.7 hours in a nitrogen atmosphere. After the reaction was completed, the linker was filtered and evaporated.

[0045] Preparation Example 4:

[0046] The preparation of the linker comprises the following steps:

[0047] 60 parts by weight of dicyandiamide, 25 parts by weight of methylhydrodichlorosilane and 15 parts by weight of triethylamine were dispersed in 500 parts by weight of n-hexane, and stirred at 15° C. for 4 hours in a nitrogen atmosphere. After the reaction was completed, the mixture was filtered and rotary evaporated to obtain a linker.

[0048] Preparation Example 5:

[0049] The preparation of the linker comprises the following steps:

[0050] 60 parts by weight of 1,2-propylenediamine, 25 parts by weight of methylhydrodichlorosilane and 15 parts by weight of triethylamine were dispersed in 500 parts by weight of n-hexane, and stirred at 15° C. for 4 hours in a nitrogen atmosphere. After the reaction was completed, the mixture was filtered and rotary evaporated to obtain a linker.

[0051] Preparation Example 6:

[0052] The preparation of the linker comprises the following steps:

[0053] 60 parts by weight of dicyandiamide and 15 parts by weight of triethylamine were dispersed in 500 parts by weight of n-hexane, and stirred at 15° C. for 4 hours in a nitrogen atmosphere. After the reaction was completed, the mixture was filtered and evaporated to obtain a linker.

[0054] Preparation Example 7:

[0055] The preparation of modified carbon fiber comprises the following steps:

[0056] The chopped carbon fibers were dispersed in acetone and ultrasonically treated for 10 minutes, then kept at 80°C for 8 hours for desizing, and dried at 60°C for 24 hours to obtain desizing carbon fibers; the desizing carbon fibers were dispersed in 65% concentrated nitric acid, kept at 60°C for 2 hours for oxidation, and rinsed with distilled water several times to remove the residual acid on the surface, and dried at 60°C for 24 hours to obtain oxidized carbon fibers; 10 parts by weight of magnesium nitrate hexahydrate and 2 parts by weight of 2-aminoterephthalic acid were dispersed in 300 parts by weight of a mixed solvent (V N,N-二甲基甲酰胺 :V 无水乙醇 :V 去离子水 =15:1:1) to obtain a mixture, 5 parts by weight of oxidized carbon fibers are dispersed in the mixture and kept at 120° C. for 20 hours to perform a solvent thermal reaction, and after the reaction is completed, the modified carbon fibers are obtained by washing and drying.

[0057] Preparation Example 8:

[0058] The preparation of modified carbon fiber comprises the following steps:

[0059] The chopped carbon fibers were dispersed in acetone and ultrasonically treated for 12 minutes, then kept at 81°C for 8.5 hours for desizing, and dried at 65°C for 24 hours to obtain desizing carbon fibers. The desizing carbon fibers were dispersed in 65% concentrated nitric acid and kept at 62°C for 3 hours for oxidation. After the heat preservation, they were rinsed with distilled water several times to remove the residual acid on the surface, and dried at 63°C for 24 hours to obtain oxidized carbon fibers. 12 parts by weight of magnesium nitrate hexahydrate and 2.3 parts by weight of 2-aminoterephthalic acid were dispersed in 300 parts by weight of a mixed solvent (V N,N-二甲基甲酰胺 :V 无水乙醇 :V 去离子水 =15:1:1) to obtain a mixture, 6 parts by weight of oxidized carbon fibers are dispersed in the mixture and kept at 121° C. for 22 hours to perform a solvent thermal reaction, and after the reaction is completed, the modified carbon fibers are obtained by washing and drying.

[0060] Preparation Example 9:

[0061] The preparation of modified carbon fiber comprises the following steps:

[0062] The chopped carbon fibers were dispersed in acetone and ultrasonically treated for 15 minutes, then desized at 83°C for 9 hours, and dried at 70°C for 24 hours to obtain desized carbon fibers. The desized carbon fibers were dispersed in 65% concentrated nitric acid and oxidized at 66°C for 4 hours. After the insulation, the fibers were rinsed with distilled water several times to remove the residual acid on the surface, and dried at 67°C for 24 hours to obtain oxidized carbon fibers. 13 parts by weight of magnesium nitrate hexahydrate and 2.5 parts by weight of 2-aminoterephthalic acid were dispersed in 300 parts by weight of a mixed solvent (V N,N-二甲基甲酰胺 :V 无水乙醇:V 去离子水 =15:1:1) to obtain a mixture, 57 parts by weight of oxidized carbon fibers are dispersed in the mixture and kept at 123° C. for 23 hours to perform a solvent thermal reaction, and after the reaction is completed, the modified carbon fibers are obtained by washing and drying.

[0063] Preparation Example 10:

[0064] The preparation of modified carbon fiber comprises the following steps:

[0065] The chopped carbon fibers were dispersed in acetone and ultrasonically treated for 20 minutes, then kept at 85°C for 10 hours for desizing, and dried at 80°C for 24 hours to obtain desizing carbon fibers; the desizing carbon fibers were dispersed in 65% concentrated nitric acid and kept at 70°C for 6 hours for oxidation, and then rinsed with distilled water several times to remove the residual acid on the surface, and dried at 70°C for 24 hours to obtain oxidized carbon fibers; 15 parts by weight of magnesium nitrate hexahydrate and 3 parts by weight of 2-aminoterephthalic acid were dispersed in 300 parts by weight of a mixed solvent (V N,N-二甲基甲酰胺 :V 无水乙醇 :V 去离子水 =15:1:1) to obtain a mixture, 8 parts by weight of oxidized carbon fibers are dispersed in the mixture and kept at 125° C. for 24 hours to perform a solvent thermal reaction, and after the reaction is completed, the modified carbon fibers are obtained by washing and drying.

[0066] Preparation Example 11:

[0067] The preparation of modified carbon fiber comprises the following steps:

[0068] The chopped carbon fibers were dispersed in acetone and ultrasonically treated for 20 minutes, then kept at 85°C for 10 hours for desizing, and dried at 80°C for 24 hours to obtain desizing carbon fibers; the desizing carbon fibers were dispersed in 65% concentrated nitric acid and kept at 70°C for 6 hours for oxidation, and then rinsed with distilled water several times to remove the residual acid on the surface, and dried at 70°C for 24 hours to obtain oxidized carbon fibers; 15 parts by weight of magnesium nitrate hexahydrate and 3 parts by weight of terephthalic acid were dispersed in 300 parts by weight of a mixed solvent (V N,N-二甲基甲酰胺 :V 无水乙醇 :V 去离子水 =15:1:1) to obtain a mixture, 8 parts by weight of oxidized carbon fibers are dispersed in the mixture and kept at 125° C. for 24 hours to perform a solvent thermal reaction, and after the reaction is completed, the modified carbon fibers are obtained by washing and drying.

[0069] Preparation Example 12:

[0070] The preparation of modified carbon fiber comprises the following steps:

[0071] The chopped carbon fibers were dispersed in acetone and ultrasonically treated for 20 minutes, then kept at 85°C for 10 hours for desizing, and dried at 80°C for 24 hours to obtain desizing carbon fibers. The desizing carbon fibers were dispersed in 65% concentrated nitric acid and kept at 70°C for 6 hours for oxidation. After the heat preservation, they were rinsed with distilled water several times to remove the residual acid on the surface, and dried at 70°C for 24 hours to obtain oxidized carbon fibers. 15 parts by weight of manganese chloride tetrahydrate and 3 parts by weight of 2-aminoterephthalic acid were dispersed in 300 parts by weight of a mixed solvent (V N,N-二甲基甲酰胺 :V 无水乙醇 :V 去离子水 =15:1:1) to obtain a mixture, 8 parts by weight of oxidized carbon fibers are dispersed in the mixture and kept at 125° C. for 24 hours to perform a solvent thermal reaction, and after the reaction is completed, the modified carbon fibers are obtained by washing and drying.

[0072] Example 1:

[0073] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0074] The dried sedge was cut into 1 cm lengths, heated to 250°C at a heating rate of 10°C / min in a nitrogen atmosphere and kept warm for 1 hour. After the heat preservation, it was washed alternately with anhydrous ethanol and deionized water for 3 times, and dried at 60°C for 8 hours to obtain a carbon precursor; 10 parts by weight of the carbon precursor and 15 parts by weight of the connector prepared in Preparation Example 1 were dispersed in 100 parts by weight of anhydrous ethanol, stirred at 60°C for 12 hours for the first impregnation reaction, and after the reaction was completed, 1 part by weight of the modified carbon fiber prepared in Preparation Example 7 and 0.15 parts by weight of scandium trifluoromethanesulfonate were stirred at 25°C for 4 hours to perform a second impregnation reaction, and then dried at 90°C for 6 hours after centrifugal slurry removal and natural air drying to obtain a precursor; the precursor obtained above was heated to 1000°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 3 hours for pyrolysis. After the reaction, the temperature was lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 8°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0075] Example 2:

[0076] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0077] Dried sedge grass was cut into 1 cm lengths and heated to 280°C at a heating rate of 12°C / min in a nitrogen atmosphere for 1.3 h. After the heating, it was washed three times with anhydrous ethanol and deionized water, respectively, and dried at 62°C for 9 h to obtain a carbon precursor. 12 parts by weight of the carbon precursor and 20 parts by weight of the connector prepared in Preparation Example 2 were dispersed in 100 parts by weight of anhydrous ethanol and stirred at 62°C for 15 h for a first impregnation reaction. After the reaction, 1.2 parts by weight of the modified carbon fiber prepared in Preparation Example 8 and 0. 19 parts by weight of scandium trifluoromethanesulfonate were stirred and reacted at 26°C for 4.5 hours to perform a second impregnation reaction, and then dried at 92°C for 6.5 hours after centrifugal slurry removal and natural air drying to obtain a precursor; the above-obtained precursor was heated to 1200°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 3.5 hours for pyrolysis. After the reaction, the temperature was lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 8.5°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0078] Example 3:

[0079] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0080] The dried sedge was cut into 1 cm lengths, heated to 300°C at a heating rate of 15°C / min in a nitrogen atmosphere and kept warm for 1.8 h. After the end of the heat preservation, it was washed alternately with anhydrous ethanol and deionized water three times, and dried at 66°C for 10 h to obtain a carbon precursor; 14 parts by weight of the carbon precursor and 25 parts by weight of the connector prepared in Preparation Example 3 were dispersed in 100 parts by weight of anhydrous ethanol, stirred at 67°C for 20 h for the first impregnation reaction, and after the reaction was completed, 1.5 parts by weight of the modified carbon fiber prepared in Preparation Example 9 was added. The precursor was prepared by stirring 0.22 parts by weight of scandium trifluoromethanesulfonate at 28°C for 5 hours to carry out a second impregnation reaction, and then drying it at 96°C for 7 hours after centrifugal slurry removal and natural air drying. The precursor was heated to 1400°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 3.5 hours for pyrolysis. After the reaction, the temperature was lowered to 800°C at a cooling rate of 2°C / min, and then to 100°C at a rate of 9°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0081] Example 4:

[0082] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0083] The dried sedge was cut into 1 cm lengths, heated to 350°C at a heating rate of 15°C / min in a nitrogen atmosphere and kept warm for 2 h. After the heat preservation, it was washed alternately with anhydrous ethanol and deionized water for 3 times, and dried at 70°C for 12 h to obtain a carbon precursor; 15 parts by weight of the carbon precursor and 30 parts by weight of the connector prepared in Preparation Example 4 were dispersed in 100 parts by weight of anhydrous ethanol, stirred at 70°C for 24 h for the first impregnation reaction, and after the reaction was completed, 2 parts by weight of the modified carbon fiber prepared in Preparation Example 10 and 0.25 parts by weight of scandium trifluoromethanesulfonate were stirred and reacted at 30°C for 6 hours for a second impregnation reaction, and then dried at 100°C for 8 hours after centrifugal slurry removal and natural air drying to obtain a precursor; the above-obtained precursor was heated to 1500°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 4 hours for pyrolysis. After the reaction, the temperature was lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 10°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0084] Comparative Example 1:

[0085] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0086] The dried sedge was cut into 1 cm lengths, heated to 350°C at a heating rate of 15°C / min in a nitrogen atmosphere and kept warm for 2 h. After the heat preservation, it was washed alternately with anhydrous ethanol and deionized water for 3 times, and dried at 70°C for 12 h to obtain a carbon precursor; 15 parts by weight of the carbon precursor and 30 parts by weight of the connector prepared in Preparation Example 5 were dispersed in 100 parts by weight of anhydrous ethanol, stirred at 70°C for 24 h for the first impregnation reaction, and after the reaction was completed, 2 parts by weight of the modified carbon fiber prepared in Preparation Example 10 and 0.25 parts by weight of scandium trifluoromethanesulfonate were stirred and reacted at 30°C for 6 hours for a second impregnation reaction, and then dried at 100°C for 8 hours after centrifugal slurry removal and natural air drying to obtain a precursor; the above-obtained precursor was heated to 1500°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 4 hours for pyrolysis. After the reaction, the temperature was lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 10°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0087] Comparative Example 2:

[0088] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0089] The dried sedge was cut into 1 cm lengths, heated to 350°C at a heating rate of 15°C / min in a nitrogen atmosphere and kept warm for 2 h. After the heat preservation, it was washed alternately with anhydrous ethanol and deionized water for 3 times, and dried at 70°C for 12 h to obtain a carbon precursor; 15 parts by weight of the carbon precursor and 30 parts by weight of the connector prepared in Preparation Example 6 were dispersed in 100 parts by weight of anhydrous ethanol, stirred at 70°C for 24 h for the first impregnation reaction, and after the reaction was completed, 2 parts by weight of the modified carbon fiber prepared in Preparation Example 10 and 0.25 parts by weight of scandium trifluoromethanesulfonate were stirred and reacted at 30°C for 6 hours for a second impregnation reaction, and then dried at 100°C for 8 hours after centrifugal slurry removal and natural air drying to obtain a precursor; the above-obtained precursor was heated to 1500°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 4 hours for pyrolysis. After the reaction, the temperature was lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 10°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0090] Comparative Example 3:

[0091] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0092] The dried sedge was cut into 1 cm lengths, heated to 350°C at a heating rate of 15°C / min in a nitrogen atmosphere and kept warm for 2 h. After the heat preservation, it was washed alternately with anhydrous ethanol and deionized water three times, and dried at 70°C for 12 h to obtain a carbon precursor; 15 parts by weight of the carbon precursor and 30 parts by weight of the connector prepared in Preparation Example 4 were dispersed in 100 parts by weight of anhydrous ethanol, stirred at 70°C for 24 h for the first impregnation reaction, and after the reaction was completed, 2 parts by weight of the modified carbon fiber prepared in Preparation Example 11 and 0.25 parts by weight of scandium trifluoromethanesulfonate were stirred and reacted at 30°C for 6 hours for a second impregnation reaction, and then dried at 100°C for 8 hours after centrifugal slurry removal and natural air drying to obtain a precursor; the above-obtained precursor was heated to 1500°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 4 hours for pyrolysis. After the reaction, the temperature was lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 10°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0093] Comparative Example 4:

[0094] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0095] The dried sedge was cut into 1 cm lengths, heated to 350°C at a heating rate of 15°C / min in a nitrogen atmosphere and kept warm for 2 h. After the heat preservation, it was washed alternately with anhydrous ethanol and deionized water three times, and dried at 70°C for 12 h to obtain a carbon precursor; 15 parts by weight of the carbon precursor and 30 parts by weight of the connector prepared in Preparation Example 4 were dispersed in 100 parts by weight of anhydrous ethanol, stirred at 70°C for 24 h for the first impregnation reaction, and after the reaction was completed, 2 parts by weight of the modified carbon fiber prepared in Preparation Example 12 and 0.25 parts by weight of scandium trifluoromethanesulfonate were stirred and reacted at 30°C for 6 hours for a second impregnation reaction, and then dried at 100°C for 8 hours after centrifugal slurry removal and natural air drying to obtain a precursor; the above-obtained precursor was heated to 1500°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 4 hours for pyrolysis. After the reaction, the temperature was lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 10°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0096] Comparative Example 5:

[0097] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0098] The dried sedge was cut into 1 cm lengths, heated to 350°C at a heating rate of 15°C / min in a nitrogen atmosphere and kept warm for 2 h. After the heat preservation, it was washed alternately with anhydrous ethanol and deionized water three times, and dried at 70°C for 12 h to obtain a carbon precursor; 15 parts by weight of carbon precursor and 30 parts by weight of hexamethyldisilazane were dispersed in 100 parts by weight of anhydrous ethanol, stirred at 70°C for 24 h for the first impregnation reaction, and after the reaction was completed, 2 parts by weight of the modified carbon fiber obtained in Preparation Example 12 and 0 .25 parts by weight of scandium trifluoromethanesulfonate were stirred and reacted at 30°C for 6 hours for a second impregnation reaction, and then dried at 100°C for 8 hours after centrifugal slurry removal and natural air drying to obtain a precursor; the precursor obtained above was heated to 1500°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 4 hours for pyrolysis. After the reaction, the temperature was lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 10°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0099] Comparative Example 6:

[0100] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0101] The dried sedge was cut into 1 cm lengths, heated to 350°C at a heating rate of 15°C / min in a nitrogen atmosphere and kept warm for 2 h. After the heat preservation, it was washed alternately with anhydrous ethanol and deionized water for 3 times, and dried at 70°C for 12 h to obtain a carbon precursor; 15 parts by weight of the carbon precursor and 30 parts by weight of the connector prepared in Preparation Example 4 were dispersed in 100 parts by weight of anhydrous ethanol, stirred at 70°C for 24 h for the first impregnation reaction, and after the reaction was completed, 2 parts by weight of chopped carbon fibers and 0.25 parts by weight of the carbon precursor were added. The weight parts of scandium trifluoromethanesulfonate were stirred and reacted at 30°C for 6 hours to carry out a second impregnation reaction, and then dried at 100°C for 8 hours after centrifugal slurry removal and natural air drying to obtain a precursor; the above-obtained precursor was heated to 1500°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 4 hours for pyrolysis. After the reaction, the temperature was lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 10°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0102] Comparative Example 7:

[0103] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0104] The dried sedge grass was crushed and passed through an 80-mesh sieve to obtain sedge grass powder. 30 parts by weight of sedge grass powder was dispersed in 100 parts by weight of a mixed solvent (V 甲苯 :V 乙醇 =2:1) ​​and reacted at 80°C for 8h, after the reaction was completed, filtered, washed and dried to obtain pretreated sedge grass powder; 20 parts by weight of pretreated sedge grass powder were dispersed in 600 parts by weight of a mixed solution consisting of sodium hydroxide and hydrogen peroxide (wherein the concentration of sodium hydroxide was 6% and the concentration of hydrogen peroxide was 0.7%), ultrasonicated at 25°C for 15min, stirred and reacted at 90°C for 3h, after the reaction was completed, filtered, washed and dried to obtain alkali-treated sedge grass; the alkali-treated sedge grass obtained above was dispersed in an acetic acid solution with a pH of 6.5 and stirred and reacted at 70°C for 4h, after the reaction was completed, filtered, washed and dried to obtain sedge grass cellulose; 15 parts by weight of sedge grass cellulose and 30 parts by weight of the continuous The binder is dispersed in 100 parts by weight of anhydrous ethanol and stirred at 70°C for 24 hours for a first impregnation reaction. After the reaction is completed, 2 parts by weight of the modified carbon fiber obtained in Preparation Example 10 and 0.25 parts by weight of scandium trifluoromethanesulfonate are added and stirred at 30°C for 6 hours for a second impregnation reaction. Subsequently, the precursor is dried at 100°C for 8 hours after centrifugal slurrying and natural air drying. The precursor obtained above is heated to 1500°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 4 hours for pyrolysis. After the reaction is completed, the temperature is lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 10°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0105] Comparative Example 8:

[0106] The preparation of an impact-resistant carbon fiber foam composite material comprises the following steps:

[0107] 2 parts by weight of carbon fiber, 50 parts by weight of silicon carbide powder, 3 parts by weight of silica powder and 20 parts by weight of deionized water are vacuum ball-milled for 3 hours to obtain a ceramic slurry, and polyurethane foam is immersed in the above ceramic slurry under vacuum conditions. After impregnation, the slurry is centrifuged and naturally air-dried, and then dried at 100°C for 8 hours to obtain a precursor; the precursor obtained above is heated to 1500°C at a heating rate of 5°C / min in a nitrogen protection environment and kept warm for 4 hours for pyrolysis. After the reaction is completed, the temperature is lowered to 800°C at a cooling rate of 2°C / min, and then lowered to 100°C at a rate of 10°C / min and then naturally cooled to obtain an impact-resistant carbon fiber foam composite material.

[0108] Performance testing:

[0109] Impact resistance: The impact resistance of the carbon fiber foam composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 8 was tested with reference to the method of QB / T 1993-2012;

[0110] Porosity: The porosity of the carbon fiber foam composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 8 was tested with reference to the method of GB / T 1966-1996;

[0111] Thermal shock stability: The thermal shock stability of the carbon fiber foam composite materials prepared in Examples 1 to 4 and Comparative Examples 1 to 8 was measured with reference to the method of GB / T 30873-2014. The specific results are shown in Table 1.

[0112]

[0113] It can be seen from the data in Table 1 that the carbon fiber foam composite materials obtained in Examples 1 to 4 have good impact strength, porosity and thermal shock stability compared with the carbon fiber foam composite materials obtained in Comparative Examples 1 to 8. The above data show that the present invention significantly improves the impact resistance of the carbon fiber foam ceramic composite material by using the product after heat treatment of dragon beard grass as the carbon skeleton, introducing a connecting agent, synthesizing Mg-MOF and connecting modified carbon fibers. These operations synergistically act from three aspects: interface bonding, stress dispersion and structural stability, so that the composite material exhibits excellent mechanical properties under impact load. The introduction of Mg-MOF increases the porosity, while the cross-linked network of the connecting agent and cellulose optimizes the pore distribution, making the voids of the composite material more uniform. The connection of the modified carbon fibers enhances the interfacial bonding strength between the fiber and the matrix, so that the material can better resist the interface peeling caused by thermal stress during thermal shock.

[0114] The embodiments described above provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A process for preparing an impact-resistant carbon fiber foam composite material, characterized in that: The preparation process comprises the following steps: The carbon precursor is obtained by heat-treating the sedge, and the carbon precursor, a connector, and anhydrous ethanol are mixed to undergo a first impregnation reaction. After the reaction, modified carbon fiber and a first catalyst are added to undergo a second impregnation reaction to obtain a precursor. The precursor is subjected to a pyrolysis reaction to obtain the impact-resistant carbon fiber foam composite material. The first catalyst is scandium trifluoromethanesulfonate. The pyrolysis reaction includes a reaction temperature of 1000-1500° C. and a reaction time of 3-4 hours. The heat treatment temperature is 250°C, 280°C, 300°C or 350°C; The preparation method of the linker comprises the following steps: dicyandiamide, methyldichlorosilane and a second catalyst are dispersed in n-hexane, and stirred in an inert gas protection environment to react to prepare the linker; the second catalyst is triethylamine; The preparation method of the modified carbon fiber comprises the following steps: chopped carbon fibers are sequentially desized and oxidized to obtain oxidized carbon fibers, magnesium nitrate hexahydrate, 2-aminoterephthalic acid and a mixed solvent are mixed to obtain a mixture, and the oxidized carbon fibers are dispersed in the mixture and subjected to a solvent thermal reaction to obtain the modified carbon fibers.

2. A process for preparing an impact-resistant carbon fiber foam composite material according to claim 1, characterized in that: The weight ratio of the dicyandiamide, methylhydrogendichlorosilane and the second catalyst is 45-60:20-25:10-15.

3. The process for preparing an impact-resistant carbon fiber foam composite material according to claim 1, wherein: The weight ratio of the magnesium nitrate hexahydrate to 2-aminoterephthalic acid is 10-15:2-3.

4. The process for preparing an impact-resistant carbon fiber foam composite material according to claim 1, wherein: The weight ratio of the magnesium nitrate hexahydrate to the oxidized carbon fiber is 10-15:5-8.

5. The process for preparing the impact-resistant carbon fiber foam composite material according to claim 1, wherein: The weight ratio of the carbon precursor, the connector and the modified carbon fiber is 10-15:3-5:1-2.

6. The process for preparing the impact-resistant carbon fiber foam composite material according to claim 1, wherein: The weight ratio of the modified carbon fiber to the first catalyst is 1-2:0.15-0.25.

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