Multistage carbon-assisted reactive infiltration modified carbon-carbon composite material and preparation method thereof

Abstract

The invention discloses a multistage carbon-assisted reactive infiltration modified carbon-carbon composite material and a preparation method thereof, and belongs to the technical field of composite material preparation. The method comprises the following steps: firstly, melting carbohydrates through heat treatment, spontaneously wrapping hard ceramic particles by utilizing the fluidity and viscosity of the carbohydrates after being heated and melted, and continuously heating to obtain ceramic particles uniformly coated with pyrolytic carbon; ceramic particles uniformly coated with pyrolytic carbon and nanoscale porous carbon powder are introduced into the carbon / carbon composite material to prepare the carbon / carbon composite material with a multi-stage carbon structure, and through the arrangement of the multi-stage carbon structure, the internal pore structure of the composite material is refined through mutual stacking of the particles; a multi-stage carbon structure with high reaction activity and high specific surface area is beneficial to full reaction of molten alloy, residual metal is reduced, the grain size of generated ceramic is refined, meanwhile, a matrix is reinforced by ceramic hard particles, and preparation of the high-performance ceramic modified carbon / carbon composite material is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material preparation, and in particular relates to a multi-stage carbon-assisted reaction infiltration modified carbon-carbon composite material and a preparation method thereof. Background Art

[0002] Carbon / carbon (C / C) composites have been widely used in the aerospace industry due to their mechanical properties, which increase with increasing temperature, combining low density with high specific strength. However, C / C composites oxidize at 400°C in an aerobic environment, and the oxidation rate increases rapidly with increasing temperature, severely limiting their application. Therefore, the incorporation of ultra-high-temperature ceramics (UHT) with excellent high-temperature oxidation resistance into C / C composites offers a solution for the structural design of components for use in extreme environments such as supersonic flight and rocket engines. Reactive melt infiltration (RMI) has become the preferred process for incorporating UHT ceramic components into C / C composites due to its low cost, high densification efficiency, and short infiltration cycle. This technique involves embedding the composite material in alloy powder, which is then melted at high temperature to form an alloy melt. The melt infiltrates into the matrix under the influence of capillary forces and gravity, where the alloy melt reacts with the matrix. Zhao Rida (Zhao Rida, Tang Sufang. Research Progress on Preparation of Ceramic Matrix Composites by Modified Reactive Melt Infiltration of Porous Carbon Ceramics [J]. Journal of Inorganic Materials, 2024, 39(06): 623-633) proposed that the fundamental reason for the defects of the RMI process is that the degree of ceramicization of the traditional carbon / boron matrix is ​​too low. For this reason, a large amount of unreacted matrix remains in the ceramic matrix composite. At the same time, due to the low consumption of the reaction melt, a large amount of reaction melt remains in the pores and etches adjacent fibers. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material and a preparation method thereof, so as to solve the problem in the prior art that, during the reactive infiltration process, the alloy melt and the matrix do not react sufficiently, resulting in a large amount of unreacted matrix and reactive melt inside the final ceramic-based composite material.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material comprises the following steps: S1, mixing sugar powder and 1-3 μm ZrC powder, and grinding to obtain a mixed powder; S2, heat-treating the mixed powder to obtain pyrolytic carbon-coated ceramic particles; S3, grinding pyrolytic carbon coated ceramic particles, wherein the particle size of the ground pyrolytic carbon coated ceramic particles is less than 10 μm, dispersing the ground pyrolytic carbon coated ceramic particles in anhydrous ethanol, and stirring to obtain a pyrolytic carbon coated ceramic particle suspension; dispersing porous carbon powder in anhydrous ethanol, and stirring to obtain a porous carbon suspension, wherein the specific surface area of ​​the porous carbon powder is 1000-1200 m 2 / g, particle size is 100-500nm; S4, introducing the pyrolytic carbon-coated ceramic particles in the pyrolytic carbon-coated ceramic particle suspension into the carbon-carbon composite material by vacuum filtration; introducing the porous carbon in the porous carbon suspension into the carbon-carbon composite material by vacuum filtration to obtain a composite material having a multi-level carbon structure; S5, placing the composite material with a multi-level carbon structure in a crucible, performing alloy compound reaction infiltration, and obtaining a ceramic-modified carbon-carbon composite material.

[0005] A further improvement of the present invention is: Preferably, in S1, the mixing mass ratio of the saccharide powder to the ZrC powder is 1:(3-3.5).

[0006] Preferably, in S1, the sugar powder is glucose or sucrose.

[0007] Preferably, in S2, the heat treatment temperature is 600-1000°C, and the heat treatment time is 2-3h.

[0008] Preferably, in S2, during the heat treatment process, argon gas is introduced into the heat treatment furnace.

[0009] Preferably, in S4, the mass ratio of the porous carbon in the porous carbon suspension to the pyrolytic carbon-coated ceramic particles in the pyrolytic carbon-coated ceramic particle suspension is 1:(100-500).

[0010] Preferably, in S5, the reaction infiltration temperature is 1800-2000°C, and the reaction infiltration time is 0.5-2h.

[0011] Preferably, in S5, the alloy compound is ZrSi2 or HfSi2.

[0012] Preferably, in S5, during the reactive infiltration process, argon gas is introduced into the reactive infiltration furnace, and the argon gas flow rate is 8-10 L / h.

[0013] A multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material prepared by any one of the above preparation methods is a SiC-ZrC modified carbon-carbon composite material, wherein the SiC and ZrC are in the form of micron-sized ceramic grains.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The application discloses a preparation method of a multi-level carbon-assisted reaction infiltration modified carbon / carbon composite material. The preparation method firstly melts sugar by heat treatment, utilizes the fluidity and viscosity of the sugar after being melted by heat to spontaneously wrap hard ceramic particles, and obtains ceramic particles uniformly coated with pyrolytic carbon after continuous heating; and the ceramic particles are introduced into the carbon / carbon composite material together with nano-level porous carbon powder to prepare the carbon / carbon composite material with a multi-level carbon structure. Through the arrangement of the multi-level carbon structure, the mutual stacking between the particles refines the pore structure in the composite material. The multi-level carbon structure with high reactivity and high specific surface area is beneficial to the full reaction of the molten alloy, reduces residual metal, and refines the grain size of the generated ceramic. Meanwhile, the ceramic hard particles reinforce the matrix, and the preparation of the high-performance ceramic modified carbon / carbon composite material is realized. The method has the following advantages. (1) The method aims to introduce the multi-level carbon structure into the low-density carbon / carbon composite material, increase the internal reaction specific surface area of the material, enhance the capillary action, introduce the hard ceramic particles to reinforce the matrix and provide nucleation sites, make the molten alloy fully react, reduce the residual metal in the composite material, and refine the grain size of the ceramic product, so that the high-performance ceramic modified composite material is prepared.

[0015] (2) Compared with the traditional large-size and dense matrix carbon, the micron or submicron carbon material has the advantages of large specific surface area, small skeleton particle and high reactivity. Therefore, the introduction of the multi-scale carbon material into the matrix can promote the full reaction of the preform matrix and the melt to a certain extent.

[0016] (3) The pyrolytic carbon coated ceramic particles provide a carbon source for the reaction of the alloy melt. The introduced porous carbon powder has high specific surface area and high reactivity, can be used as an additional carbon source to fully react with the infiltrated alloy melt, prevents the loss of the melt, and reduces the residual alloy and the grain size of the generated ceramic product under the synergistic action of the two.

[0017] (4) After the pyrolytic carbon coated ceramic particles with a particle size of 10 microns or less are introduced, the mutual stacking between the powder particles divides the large pores into many small pore structures, avoids the difficulty of introducing a particle size that is too large, prevents the pore from being filled and saturated due to a particle size that is too small, and provides a channel for the further introduction of nano-level porous carbon powder. The nano-level porous carbon powder with a specific surface area of 1000-1200 m 2 / g introduced subsequently further divides the small pores into microporous structures, and organically cooperates with the micropores in the porous carbon to form interpenetrating connections, maximally enhances the capillary force in the infiltration process, is beneficial to the infiltration of the melt, and improves the reaction infiltration efficiency.

[0018] (5) The hard ceramic particles introduced play a role in strengthening the matrix during the infiltration process. On the other hand, they increase the introduction of ceramic components, regulate the ceramic content inside the matrix, and can select the required ceramic components according to the service temperature, thus realizing wide temperature range regulation of the composite material performance.

[0019] (6) The use of sugars to coat hard ceramic particles is safe and simple, making it suitable for large-scale coating of pyrolytic carbon. The raw materials used in this preparation process are low-cost, the preparation cycle is short, the preparation process is simple and easy to scale up, and it is not limited by the shape and size of the composite material, which has strong industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is pyrolytic carbon-coated ZrC powder; Figure 2 Scanning electron microscope image of the introduction of a hierarchical carbon structure into a low-density composite material; Figure 3 This is a scanning electron microscope image of the multi-level carbon structure introduced into the low-density composite material in Example 1; Figure 4 This is a scanning electron microscope image of the multi-level carbon structure introduced into the low-density composite material in Example 2; Figure 5 This is a scanning electron microscope image of the low-density composite material introduced with a multi-level carbon structure in Example 3; Figure 6 This is a scanning electron microscope image of the low-density composite material in Comparative Example 1, showing the introduction of a multi-level carbon structure. Figure 7 This is a scanning electron microscope image of the low-density composite material in Comparative Example 2, showing the introduction of a multi-level carbon structure. Figure 8 is a scanning electron microscope image of the composite material after reactive infiltration in Example 1; Figure 9 is a scanning electron microscope image of the composite material after reactive infiltration in Example 2; Figure 10 is a scanning electron microscope image of the composite material after reactive infiltration in Example 3; Figure 11 This is a scanning electron microscope image of the composite material after reactive infiltration in Comparative Example 1; Figure 12 This is a scanning electron microscope image of the composite material after reactive infiltration in Comparative Example 2. DETAILED DESCRIPTION

[0021] The present invention is described in further detail below with reference to the accompanying drawings: To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0022] In this document, unless otherwise specified, “include,” “including,” “contains,” “has” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0023] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0024] The following examples were prepared using conventional instruments and equipment in the art. Experimental methods in the following examples, where specific conditions are not specified, were generally performed under conventional conditions or according to the conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, were conventional commercially available products, with specifications conventional in the art. In the present specification and the following examples, unless otherwise specified, "%" indicates percentage by weight, "part" indicates parts by weight, and "ratio" indicates weight ratio.

[0025] The first aspect of the present invention discloses a method for preparing a multi-level carbon structure-assisted composite material by reactive infiltration, comprising the following steps: S1, preparing a mixed powder of sugar powder and ZrC powder: weighing 1 g of glucose or sucrose powder, pouring it into a mortar and grinding it thoroughly, then weighing 3-3.5 g of ZrC powder with a particle size of 1-3 μm, pouring it into the mortar and continuing to grind it, and after 10 minutes, the two powders are completely mixed to obtain a mixed powder; S2, heat treatment of mixed powder: the mixed powder weighed and prepared according to the above proportion is placed in an alumina crucible, and then the alumina crucible is placed in a heat treatment furnace at 600℃-1000℃ for 2-3h, with a heating rate of 5℃ / min and a cooling rate of 5℃ / min. The heat treatment furnace is an argon atmosphere with an argon flow rate of 2-4 L / h to obtain a heat treatment product, which is pyrolytic carbon-coated ceramic particles.

[0026] In the above process, ZrC powder is one of the main materials with strong mechanical properties, high hardness and strong ablation resistance. First, the sugar and ZrC powder are physically mixed so that the two can be mixed evenly; in the subsequent heat treatment process, the fluidity and viscosity of the sugar after melting by heat spontaneously wrap around the hard ceramic particles, and after continuing to heat up, ceramic particles uniformly coated with pyrolytic carbon are obtained; at this time, the pyrolytic carbon is in the form of micron-sized particles, which are coated on the surface of the ZrC powder. After the ZrC powder is coated, the surface is no longer a smooth sphere, and more nano-scale pores will be formed between the pyrolytic carbon, and the volume of each ZrC powder becomes larger, which is convenient for the subsequent introduction of nano-scale porous carbon.

[0027] S3, prepare the suspension: put the heat-treated product into a mortar and grind it thoroughly to a particle size of less than 10μm, then select porous carbon powder with a specific surface area of ​​1000-1200 and a particle size of 100-500nm, mix the two with anhydrous ethanol in a mass ratio of 1:10, put them into a magnetic rotor, and use a magnetic stirrer to fully stir to prepare two suspensions, respectively obtaining a pyrolytic carbon-coated ceramic particle suspension and a porous carbon suspension.

[0028] S4, introduce powder by vacuum filtration: pour the suspension of pyrolytic carbon-coated ceramic particles into a vacuum filtration device, use vacuum filtration to introduce the pyrolytic carbon-coated ceramic particles into the low-density carbon-carbon composite material, and then introduce nano-porous carbon powder into the carbon-carbon composite material by vacuum filtration, so that the pore structure inside the composite material is gradually filled to saturation. The mass ratio of the introduced nano-porous carbon to the pyrolytic carbon-coated ceramic particles is 1:100-1:500.

[0029] By introducing particles of two size levels into the carbon-carbon composite material through vacuum filtration, the two types of materials can be efficiently introduced into the carbon-carbon composite material, and the nano-scale porous carbon can penetrate into the pyrolytic carbon outside the micron-scale ceramic particles; this structure forms a two-level embedding, the pyrolytic carbon-coated ceramic particles can divide the pores inside the carbon-carbon composite material into pores of smaller levels, and the nano-scale porous carbon can divide the pores between the pyrolytic carbon into smaller microporous structures, so that the various materials inside the entire carbon-carbon composite material are interpenetrating and connected, maximizing the capillary force in the infiltration process, which is beneficial to the infiltration of the melt.

[0030] S5, Reactive Infiltration Treatment: The introduced hierarchical carbon composite material is placed in a graphite crucible and coated with alloy compound powder. The crucible is then heat-treated in a furnace at 1800-2000°C for 0.5-2 hours to produce a ceramic-modified composite material. The alloy compound powders include ZrSi2, HfSi2, etc. The heat treatment furnace is operated in an argon atmosphere at a flow rate of 8-10 L / h.

[0031] The second aspect of the present invention discloses a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material, which is a SiC-ZrC modified carbon-carbon composite material. The SiC and ZrC are in the form of micron-sized ceramic grains, have less residual alloy, and the residual alloy is discretely distributed.

[0032] The following is further described with reference to specific embodiments.

[0033] Example 1 S1. Prepare mixed powder: Prepare mixed powder of glucose and ZrC: weigh 1g of glucose powder, pour it into a mortar and grind it thoroughly, then weigh 3g of ZrC powder with a particle size of 1-3μm, pour it into the mortar and continue grinding, and after 10 minutes, the two are completely mixed.

[0034] S2, heat treatment of mixed powder: the mixed powder weighed and prepared according to the above proportions is placed in an alumina crucible, and then the alumina crucible is placed in an 800°C heat treatment furnace for 2 h, with a heating rate of 5°C / min and a cooling rate of 5°C / min. The heat treatment furnace is filled with argon atmosphere and the argon flow rate is 2 L / h.

[0035] S3, the heat-treated product is placed in a mortar and fully ground, the ground powder and porous carbon powder are mixed with anhydrous ethanol in a mass ratio of 1:10, respectively, placed in a magnetic rotor, and fully stirred with a magnetic stirrer to prepare two suspensions.

[0036] S4, introduce powder by vacuum filtration: pour the suspension prepared by heat-treated powder and anhydrous ethanol into a vacuum filtration device, use vacuum filtration to introduce the heat-treated powder into the low-density carbon-carbon composite material, and then introduce porous carbon powder into the interior of the carbon-carbon composite material by vacuum filtration, so that the pore structure inside the composite material is gradually filled to saturation, and the mass ratio of the introduced nano-porous carbon to the pyrolytic carbon-coated ceramic particles is 1:400.

[0037] S5, Reactive Infiltration Treatment: The introduced hierarchical carbon composite material is placed in a graphite crucible and coated with ZrSi2 powder. The crucible is then heat-treated in an argon furnace at 1800°C for 2 hours at a flow rate of 8 L / h. This results in a ceramic-modified composite material.

[0038] The results show that if Figure 1 As shown in FIG, in the pyrolytic carbon-coated ceramic particles prepared by S2, the pyrolytic carbon particles encapsulate the ZrC particles; Figure 2 As shown, pyrolytic carbon-coated ceramic particles and nano-porous carbon powder are introduced into the carbon / carbon composite material to prepare a carbon / carbon composite material with a multi-level carbon structure; Figure 3As shown in the figure, the macropores inside the low-density C / C composite material are filled with pyrolytic carbon-coated zirconium carbide and nano-porous carbon powder, in which the ZrC ratio is moderate; after reactive infiltration, the pores in the low-density C / C are filled with ceramic particles with small grain size and uniform distribution, among which, Figure 8 The black part is the unreacted carbon, the gray part is the SiC phase, and the white part is the ZrC phase.

[0039] Example 2: S1. Prepare mixed powder: Prepare mixed powder of glucose and ZrC: weigh 1g of glucose or sucrose powder, pour it into a mortar and grind it thoroughly, then weigh 3.2g of ZrC powder with a particle size of 1-3μm, pour it into the mortar and continue grinding, and after 10 minutes, the two are completely mixed.

[0040] S2, heat treatment of mixed powder: the mixed powder weighed and prepared according to the above proportions is placed in an alumina crucible, and then the alumina crucible is placed in an 800°C heat treatment furnace for 2 h, with a heating rate of 5°C / min and a cooling rate of 5°C / min. The heat treatment furnace is filled with argon atmosphere and the argon flow rate is 2 L / h.

[0041] S3, the heat-treated product is placed in a mortar and fully ground, the ground powder and porous carbon powder are mixed with anhydrous ethanol in a mass ratio of 1:10, respectively, placed in a magnetic rotor, and fully stirred with a magnetic stirrer to prepare two suspensions.

[0042] S4, introduce powder by vacuum filtration: pour the suspension prepared by heat-treated powder and anhydrous ethanol into a vacuum filtration device, use vacuum filtration to introduce the heat-treated powder into the low-density carbon-carbon composite material, and then introduce porous carbon powder into the interior of the carbon-carbon composite material by vacuum filtration, so that the pore structure inside the composite material is gradually filled to saturation, and the mass ratio of the introduced nano-porous carbon to the pyrolytic carbon-coated ceramic particles is 1:400.

[0043] S5, Reactive Infiltration Treatment: The introduced hierarchical carbon composite material is placed in a graphite crucible and coated with ZrSi2 powder. The crucible is then heat-treated in an argon furnace at 1800°C for 2 hours at a flow rate of 8 L / h. This results in a ceramic-modified composite material.

[0044] The results show that the macropores inside the low-density C / C composites are filled with pyrolytic carbon-coated zirconium carbide and nano-porous carbon powder ( Figure 4 As shown), the ZrC ratio is moderate; after reactive infiltration, the pores in the low-density C / C are filled with ceramic particles, the grain size of the ceramic particles is small and evenly distributed, among which, Figure 9The black part is the unreacted carbon, the gray part is the SiC phase, and the white part is the ZrC phase.

[0045] Example 3: S1. Prepare mixed powder: Prepare mixed powder of glucose and ZrC: weigh 1g of glucose or sucrose powder, pour it into a mortar and grind it thoroughly, then weigh 3.5g of ZrC powder with a particle size of 1-3μm, pour it into the mortar and continue grinding, and after 10 minutes, the two are completely mixed.

[0046] S2, heat treatment of mixed powder: the mixed powder weighed and prepared according to the above proportions is placed in an alumina crucible, and then the alumina crucible is placed in an 800°C heat treatment furnace for 2 h, with a heating rate of 5°C / min and a cooling rate of 5°C / min. The heat treatment furnace is filled with argon atmosphere and the argon flow rate is 2 L / h.

[0047] S3, the heat-treated product is placed in a mortar and fully ground, the ground powder and porous carbon powder are mixed with anhydrous ethanol in a mass ratio of 1:10, respectively, placed in a magnetic rotor, and fully stirred with a magnetic stirrer to prepare two suspensions.

[0048] S4, introduce powder by vacuum filtration: pour the suspension prepared by heat-treated powder and anhydrous ethanol into a vacuum filtration device, use vacuum filtration to introduce the heat-treated powder into the low-density carbon-carbon composite material, and then introduce porous carbon powder into the interior of the carbon-carbon composite material by vacuum filtration, so that the pore structure inside the composite material is gradually filled to saturation, and the mass ratio of the introduced nano-porous carbon to the pyrolytic carbon-coated ceramic particles is 1:400.

[0049] S5, Reactive Infiltration Treatment: The introduced hierarchical carbon composite material is placed in a graphite crucible and coated with ZrSi2 powder. The crucible is then heat-treated in an argon furnace at 1800°C for 2 hours at a flow rate of 8 L / h. This results in a ceramic-modified composite material.

[0050] The results show that the macropores inside the low-density C / C composites are filled with pyrolytic carbon-coated zirconium carbide and nano-porous carbon powder ( Figure 5 As shown), the ZrC ratio is moderate; after reactive infiltration, the pores in the low-density C / C are filled with ceramic particles, the grain size of the ceramic particles is small and evenly distributed, among which, Figure 10 The black part is the unreacted carbon, the gray part is the SiC phase, and the white part is the ZrC phase.

[0051] Example 4 S1. Prepare mixed powder: Prepare mixed powder of glucose and ZrC: weigh 1g of glucose or sucrose powder, pour it into a mortar and grind it thoroughly, then weigh 3.5g of ZrC powder with a particle size of 1-3μm, pour it into the mortar and continue grinding, and after 10 minutes, the two are completely mixed.

[0052] S2, heat treatment of mixed powder: the mixed powder weighed and prepared according to the above proportions is placed in an alumina crucible, and then the alumina crucible is placed in a heat treatment furnace at 600°C for 3 h, with a heating rate of 5°C / min and a cooling rate of 5°C / min. The heat treatment furnace is filled with argon atmosphere and the argon flow rate is 2 L / h.

[0053] S3, the heat-treated product is placed in a mortar and fully ground, the ground powder and porous carbon powder are mixed with anhydrous ethanol in a mass ratio of 1:10, respectively, placed in a magnetic rotor, and fully stirred with a magnetic stirrer to prepare two suspensions.

[0054] S4, introduce powder by vacuum filtration: pour the suspension prepared by heat-treated powder and anhydrous ethanol into a vacuum filtration device, use vacuum filtration to introduce the heat-treated powder into the low-density carbon-carbon composite material, and then introduce porous carbon powder into the interior of the carbon-carbon composite material by vacuum filtration, so that the pore structure inside the composite material is gradually filled to saturation, and the mass ratio of the introduced nano-porous carbon to the pyrolytic carbon-coated ceramic particles is 1:100.

[0055] S5, Reactive Infiltration Treatment: The introduced hierarchical carbon composite material is placed in a graphite crucible and coated with ZrSi2 powder. The crucible is then heat-treated in a 1900°C furnace for 1 hour in an argon atmosphere at a flow rate of 8 L / h. This results in a ceramic-modified composite material.

[0056] Example 5 S1. Prepare mixed powder: Prepare mixed powder of glucose and ZrC: weigh 1g of glucose or sucrose powder, pour it into a mortar and grind it thoroughly, then weigh 3.5g of ZrC powder with a particle size of 1-3μm, pour it into the mortar and continue grinding, and after 10 minutes, the two are completely mixed.

[0057] S2, heat treatment of mixed powder: the mixed powder weighed and prepared according to the above proportions is placed in an alumina crucible, and then the alumina crucible is placed in a heat treatment furnace at 1000°C for 2 h, with a heating rate of 5°C / min and a cooling rate of 5°C / min. The heat treatment furnace is filled with argon atmosphere and the argon flow rate is 2 L / h.

[0058] S3, the product after heat treatment was put into a mortar and ground thoroughly, the ground powder was mixed with porous carbon powder respectively according to a mass ratio of 1:10 with anhydrous ethanol, and the two suspensions were prepared by putting into a magnetic rotor and stirring thoroughly using a magnetic stirrer.

[0059] S4, vacuum filtration to introduce powder: the suspension prepared by the heat-treated powder and anhydrous ethanol was poured into a vacuum filtration device, the heat-treated powder was introduced into the low-density carbon-carbon composite material using vacuum filtration, and then the porous carbon powder was introduced into the carbon-carbon composite material by vacuum filtration, so that the pore structure inside the composite material was gradually filled to saturation.

[0060] S5, reaction infiltration treatment: the composite material with introduced multi-stage carbon structure was placed in a graphite crucible, the surface of which was covered with ZrSi2 powder, and then the graphite crucible was placed in a heat treatment furnace at 2000 ℃ for 0.5 h, the heat treatment furnace was in an argon atmosphere, and the argon flow rate was 8 L / h. Finally, a ceramic-modified composite material was prepared.

[0061] Comparative Example 1: S1, preparation of mixed powder: glucose and ZrC mixed powder was prepared: 1 g of glucose or sucrose powder was weighed and poured into a mortar and ground thoroughly, and then 2 g of ZrC powder with a particle size of 1-3 μm was weighed and poured into the mortar and continued to be ground, and after 10 min, the two were completely mixed.

[0062] S2, heat treatment of mixed powder: the mixed powder prepared according to the above ratio was placed in an alumina crucible, and then the alumina crucible was placed in a heat treatment furnace at 800 ℃ for 2 h, the heating rate was 5 ℃ / min, and the cooling rate was 5 ℃ / min, the heat treatment furnace was in an argon atmosphere, and the argon flow rate was 2 L / h.

[0063] S3, the product after heat treatment was put into a mortar and ground thoroughly, the ground powder was mixed with porous carbon powder respectively according to a mass ratio of 1:10 with anhydrous ethanol, and the two suspensions were prepared by putting into a magnetic rotor and stirring thoroughly using a magnetic stirrer.

[0064] S4, vacuum filtration to introduce powder: the suspension prepared by the heat-treated powder and anhydrous ethanol was poured into a vacuum filtration device, the heat-treated powder was introduced into the low-density carbon-carbon composite material using vacuum filtration, and then the porous carbon powder was introduced into the carbon-carbon composite material by vacuum filtration, so that the pore structure inside the composite material was gradually filled to saturation.

[0065] S5, Reactive Infiltration Treatment: The introduced hierarchical carbon composite material is placed in a graphite crucible and coated with ZrSi2 powder. The crucible is then heat-treated in an argon furnace at 1800°C for 2 hours at a flow rate of 8 L / h. This results in a ceramic-modified composite material.

[0066] The results show that the macropores inside the low-density C / C composites are filled with pyrolytic carbon-coated zirconium carbide and nano-porous carbon powder ( Figure 6 As shown), the ZrC ratio is relatively small; after reactive infiltration, the pores in the low-density C / C are filled with ceramic particles, the grain size of the ceramic particles is large and the distribution is uneven, among which, Figure 11 The black part is the unreacted carbon, the gray part is the SiC phase, and the white part is the ZrC phase.

[0067] Comparative Example 2: S1. Prepare mixed powder: Prepare mixed powder of glucose and ZrC: weigh 1g of glucose or sucrose powder, pour it into a mortar and grind it thoroughly, then weigh 5g of ZrC powder with a particle size of 1-3μm, pour it into the mortar and continue grinding, and after 10 minutes, the two are completely mixed.

[0068] S2, heat treatment of mixed powder: the mixed powder weighed and prepared according to the above proportions is placed in an alumina crucible, and then the alumina crucible is placed in an 800°C heat treatment furnace for 2 h, with a heating rate of 5°C / min and a cooling rate of 5°C / min. The heat treatment furnace is filled with argon atmosphere and the argon flow rate is 2 L / h.

[0069] S3, the heat-treated product is placed in a mortar and fully ground, the ground powder and porous carbon powder are mixed with anhydrous ethanol in a mass ratio of 1:10, respectively, placed in a magnetic rotor, and fully stirred with a magnetic stirrer to prepare two suspensions.

[0070] S4, introducing powder by vacuum filtration: pouring the suspension prepared by heat-treated powder and anhydrous ethanol into a vacuum filtration device, using vacuum filtration to introduce the heat-treated powder into the low-density carbon-carbon composite material, and then introducing the porous carbon powder into the interior of the carbon-carbon composite material by vacuum filtration, so that the pore structure inside the composite material is gradually filled and saturated.

[0071] S5, Reactive Infiltration Treatment: The introduced hierarchical carbon composite material is placed in a graphite crucible and coated with ZrSi2 powder. The crucible is then heat-treated in an argon furnace at 1800°C for 2 hours at a flow rate of 8 L / h. This results in a ceramic-modified composite material.

[0072] The results show that the macropores inside the low-density C / C composites are filled with pyrolytic carbon-coated zirconium carbide and nano-porous carbon powder ( Figure 7 As shown), the ZrC ratio is relatively large; after reactive infiltration, the pores in the low-density C / C are filled with ceramic particles, the grain size of the ceramic particles is large and the distribution is uneven, among which, Figure 12 The black part is the unreacted carbon, the gray part is the SiC phase, and the white part is the ZrC phase.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material, characterized in that: The following steps are involved: S1, mixing sugar powder and 1-3 μm ZrC powder, and grinding to obtain a mixed powder; S2, heat-treating the mixed powder to obtain pyrolytic carbon-coated ceramic particles; S3, grinding pyrolytic carbon coated ceramic particles, wherein the particle size of the ground pyrolytic carbon coated ceramic particles is less than 10 μm, dispersing the ground pyrolytic carbon coated ceramic particles in anhydrous ethanol, and stirring to obtain a pyrolytic carbon coated ceramic particle suspension; dispersing porous carbon powder in anhydrous ethanol, and stirring to obtain a porous carbon suspension, wherein the specific surface area of ​​the porous carbon powder is 1000-1200 m 2 / g, particle size is 100-500nm; S4, introducing the pyrolytic carbon-coated ceramic particles in the pyrolytic carbon-coated ceramic particle suspension into the carbon-carbon composite material by vacuum filtration; introducing the porous carbon in the porous carbon suspension into the carbon-carbon composite material by vacuum filtration to obtain a composite material having a multi-level carbon structure; S5, placing the composite material with a multi-level carbon structure in a crucible, performing alloy compound reaction infiltration, and obtaining a ceramic-modified carbon-carbon composite material.

2. The method for preparing a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material according to claim 1, characterized in that: In S1, the mixing mass ratio of sugar powder and ZrC powder is 1:(3-3.5).

3. The method for preparing a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material according to claim 1, characterized in that: In S1, the sugar powder is glucose or sucrose.

4. The method for preparing a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material according to claim 1, characterized in that: In S2, the heat treatment temperature is 600-1000°C, and the heat treatment time is 2-3 hours.

5. The method for preparing a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material according to claim 1, characterized in that: In S2, during the heat treatment process, argon gas is introduced into the heat treatment furnace.

6. The method for preparing a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material according to claim 1, characterized in that: In S4, the mass ratio of the porous carbon in the porous carbon suspension to the pyrolytic carbon-coated ceramic particles in the pyrolytic carbon-coated ceramic particle suspension is 1:(100-500).

7. The method for preparing a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material according to claim 1, characterized in that: In S5, the reaction infiltration temperature is 1800-2000°C, and the reaction infiltration time is 0.5-2h.

8. The method for preparing a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material according to claim 1, characterized in that: In S5, the alloy compound is ZrSi2 or HfSi2.

9. The method for preparing a multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material according to claim 1, characterized in that: In S5, during the reactive infiltration process, argon gas is introduced into the reactive infiltration furnace, and the argon gas flow rate is 8-10 L / h.

10. A multi-stage carbon-assisted reactive infiltration modified carbon-carbon composite material prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The SiC-ZrC modified carbon-carbon composite material is in the form of micron-sized ceramic grains.

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