A HfC x N y -SiC modified C / C composite material and preparation method thereof

Abstract

The present invention discloses a HfC x N y The invention discloses a C / C composite material modified with SiC, and a preparation method thereof, comprising: pre-treating the C / C composite material to obtain a C / C preform for infiltration; mixing HfSi2 and Si3N4 powders, and drying to obtain a powder for infiltration; placing the C / C preform for infiltration parallel to the upper layer of the powder for infiltration, and continuously adding the powder for infiltration until the C / C preform for infiltration is completely covered and higher than the upper surface of the C / C preform for infiltration, sealing, and modifying the C / C composite material by a reactive infiltration process at high temperature to obtain a C / C-HfC x N y -SiC composites; C / C-HfC x N y The HfC-SiC composite material was polished, cleaned and dried to obtain x N y -SiC modified C / C composite material. The composite material prepared by the reactive infiltration process of the present invention has strong interface bonding, excellent ablation resistance and strong anti-erosion performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of C / C composite material modification and relates to a HfC x N y -SiC modified C / C composite material and preparation method thereof. Background Art

[0002] Since their discovery in 1958, carbon / carbon composites have been widely used in aerospace hot-end components such as solid rocket motor nozzles, aircraft nose cones and leading edges, and turbine engine blades due to their low density, high thermal conductivity, high specific strength, high specific modulus, low thermal expansion coefficient, and mechanical strength that increases with increasing temperature. However, carbon / carbon composites have a high oxidative activity, and oxidation weight loss significantly reduces their strength. Their poor ablation resistance in high-enthalpy combustion environments and weak oxidative stability in oxygen-containing heat fluxes have significantly limited their application.

[0003] Ultra-high temperature ceramics (UHTCs) have a melting point of over 3000°C and a melting point of their oxides above 1800°C. They are a type of thermal protection material that can maintain relatively stable physical and chemical properties in high temperature environments (>2000°C) and plasma reaction atmospheres and can be reused above 1650°C. They are considered to be an ideal introduction material for improving the performance of C / C composites. Studies have shown that hafnium carbonitride (abbreviated as: HfC x N y ) Ultra-high temperature ceramics have a higher melting point than HfC (3890℃), better hardness, toughness and ductility, and can better meet the material performance requirements of the new generation of hypersonic aircraft service environment. However, there is currently no information about HfC. x N y There are few studies on this topic, and existing reports mainly focus on some theoretical calculations and HfC x N y Few scholars have studied the preparation and performance of ceramics. x N y As a matrix modification component, its influence on the performance of C / C composites was studied.

[0004] Reference "Zhang, J. et al. Ablation behavior of a novel carbonitridesHfC 0.68 N 0.32The HfCl4-CH4-N2-H2-Ar system was used to deposit HfC on the prefabricated SiC coating on the surface of C / C composites by CVD process. 0.68 N 0.32 The coating material shows good ablation resistance in laser and oxyacetylene atmosphere. However, the CVD coating has poor adhesion to the substrate and is prone to peeling during high temperature and long-term ablation. Summary of the Invention

[0005] The object of the present invention is to provide a HfC x N y -SiC modified C / C composite material and its preparation method solve the problem of poor interface bonding strength in the existing technology.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A HfC x N y -A method for preparing a SiC-modified C / C composite material, comprising:

[0008] Pre-treating the C / C composite material to obtain a C / C preform for infiltration;

[0009] Mix HfSi2 and Si3N4 powders and dry them to obtain powder for infiltration;

[0010] The C / C preform for infiltration is placed parallel to the upper layer of the infiltration powder, and the infiltration powder is continued to be added until the C / C preform for infiltration is completely covered and higher than the upper surface of the C / C preform for infiltration. After sealing, it is modified by the reaction infiltration process at high temperature to obtain C / C-HfC x N y -SiC composite materials;

[0011] C / C-HfC x N y -SiC composite material is polished, cleaned and dried to obtain HfC x N y -SiC modified C / C composites.

[0012] Furthermore, the pretreatment includes polishing, cleaning, boiling and drying.

[0013] Furthermore, the boiling treatment temperature is 100-350° C., and the treatment time is 1-6 hours.

[0014] Furthermore, the drying treatment temperature is 70° C. and the treatment time is 6 to 10 hours.

[0015] Furthermore, the molar ratio of the HfSi2 to Si3N4 powder is 1-4:1-4.

[0016] Furthermore, the HfSi2 and Si3N4 powders are mixed by ball milling. During the ball milling process, the ball-to-material ratio is 2:1, the rotation speed is 200-500 rpm, and the ball milling time is 4-6 hours.

[0017] Furthermore, the drying temperature of the powder for infiltration is 60-100° C., and the drying time is 8-12 hours.

[0018] Furthermore, the modification treatment conditions are: in an Ar or N2 inert atmosphere protection environment or a vacuum environment with a vacuum degree of 1 to 100 Pa, the temperature is 1600 to 2100°C, the heating rate is 4 to 10°C / min, and the holding time is 0.5 to 3h.

[0019] Furthermore, the HfC x N y The drying temperature of the SiC-modified C / C composite material is 60 to 100° C., and the drying time is 6 to 12 hours.

[0020] HfC prepared by the preparation method x N y -SiC modified C / C composites.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides a HfC x N y -SiC modified C / C composite material preparation method, using HfSi2 and Si3N4 mixed powder as infiltration agent, HfC with ultra-high melting point, strong hardness, certain toughness and ductility x N y Used for modifying C / C composites, where Si3N4 provides a nitrogen source, and the composites prepared by reactive infiltration process have strong interface bonding. In addition, the introduction of SiC makes Hf(C, N) based composites attractive for different high temperature applications. By changing the molar ratio of HfSi2 and Si3N4, the HfC x N yThe relative content of components and SiC makes the tissue composition easy to control. The process of the present invention is simple and has low requirements for equipment. Compared with hafnium carbide, hafnium carbonitride has a higher melting point. Hafnium carbonitride ceramic-based composite materials have excellent anti-ablation properties in high-temperature oxygen-containing environments. Hafnium carbonitride has higher hardness, certain toughness and ductility. Compared with other ultra-high temperature ceramic matrices, it has strong anti-erosion properties in extreme aerodynamic heat and high-speed particle erosion environments. It can better improve the service life of materials in high heat flux density, high-pressure airflow and high-speed particle erosion environments, extend the flight time of high-speed aircraft, and has great space strategic significance. At the same time, based on the present invention, HfC can also be designed more widely. x N y The preparation and performance improvement scheme of modified carbon / carbon composite materials, therefore, the development prospect of the present invention is very considerable, and the economic and social benefits are very outstanding. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 HfC of the present invention x N y -Process flow chart of the preparation method of SiC modified C / C composite material.

[0025] Figure 2 HfC prepared in Example 1 of the present invention x N y -XRD pattern of SiC modified C / C composites.

[0026] Figure 3 HfC prepared in Example 1 of the present invention x N y -SEM image of SiC modified C / C composite. DETAILED DESCRIPTION

[0027] 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.

[0028] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0029] Herein, all features such as values, amounts, amounts, and concentrations defined in numerical ranges or percentage ranges are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to include and specifically disclose all possible subranges and individual values ​​within the range (including integers and fractions).

[0030] 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.”

[0031] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0032] 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.

[0033] 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.

[0034] The present invention is described in further detail below with reference to the accompanying drawings:

[0035] See also Figure 1 The present invention provides a HfC x N y -A method for preparing a SiC-modified C / C composite material comprises the following steps:

[0036] Step 1: Select a 2.5DC / C composite material and process it into a 10mm×10mm×10mm block sample. Polish it with 50-mesh, 800-mesh, and 3000-mesh silicon carbide sandpaper, ensuring that the sample has no obvious defects and a smooth surface during melt infiltration. Ultrasonic clean the polished sample with deionized water 3-5 times, each cleaning time 30-60 minutes. Then, boil the block sample at 100-350°C for 1-6 hours until no bubbles appear on the surface of the sample, ensuring that the pores in the sample are fully open. Then, dry the sample in an electric forced air drying oven at 70°C for 6-10 hours to obtain a C / C preform for melt infiltration.

[0037] Step 2: Mix HfSi2 and Si3N4 powders in a molar ratio of 1-4:1-4, place the powder mixture and zirconia grinding balls into a corundum ball mill with a ball-to-material ratio of 2:1, then seal the corundum ball mill and use a planetary ball mill to ball mill at a speed of 200-500 rpm. After ball milling for 4-6 hours, take out the powder and place it in an electric heated blast drying oven at a temperature of 60-100°C for 8-12 hours to obtain a uniformly mixed powder for infiltration.

[0038] Step 3: The C / C composite material is modified by a reactive infiltration process, 3 to 5 layers of graphite paper are laid on the inner wall of the graphite crucible, 4 to 10 mm thick infiltration powder is laid on the bottom of the crucible, and the C / C preform for infiltration is placed parallel to the upper layer of the infiltration powder. The infiltration powder is continued to be added until it completely covers the C / C preform for infiltration and is 5 to 10 mm higher than the upper surface of the C / C preform for infiltration. During the addition of the infiltration powder, the infiltration powder is ensured to be in a loose state. After the addition of the infiltration powder is completed, it is sealed with graphite paper and carbon felt in turn, and then the crucible is sealed.

[0039] Step 4: Place the sealed crucible in a graphite furnace for high-temperature treatment. The high-temperature heat treatment conditions are: temperature of 1600-2100°C, vacuum degree of 1-100 Pa in the furnace, or in an Ar or N2 inert atmosphere, heating rate of 4-10°C / min, holding time of 0.5-3h, then power off and cool down. After the sample cools to room temperature, take it out to obtain C / C-HfC x N y -SiC composite materials.

[0040] Step 5: C / C-HfC obtained after reactive infiltration x N y-SiC composite materials were polished with 50 mesh, 800 mesh and 3000 mesh diamond grinding discs in turn to ensure that there were no obvious protrusions on the surface. The samples were then ultrasonically cleaned with deionized water for 3 to 5 times, each cleaning time was 30 to 60 minutes, and then placed in an electric blast drying oven at 60 to 100 ° C for 6 to 12 hours to obtain HfC x N y -SiC modified C / C composites.

[0041] The present invention is described in further detail below with reference to specific embodiments:

[0042] Example 1:

[0043] Step 1: Select a density of 1.1 g / cm 3 The 2.5DC / C composite material was processed into 10mm×10mm×10mm block specimens. These were then polished using 50-, 800-, and 3000-grit silicon carbide sandpaper to ensure a smooth, regular surface and no obvious defects during melt infiltration. The polished specimens were ultrasonically cleaned with deionized water five times, each lasting 30 minutes. Subsequently, the block specimens were boiled at 300°C for 3 hours until no bubbles appeared on the surface, ensuring that the pores within the specimens were fully open. The specimens were then dried in an electric forced-air drying oven at 70°C for 8 hours before use.

[0044] Step 2: Mix HfSi2 and Si3N4 powders in a molar ratio of 4:1, place the powder mixture and zirconia grinding balls into a corundum ball mill with a ball-to-material ratio of 2:1, then seal the corundum ball mill, use a planetary ball mill at a speed of 400 rpm, ball mill for 6 hours, sieve, and then place in an electric blast drying oven at a temperature of 70°C and dry for 8 hours to obtain a uniformly mixed powder mixture, which is used as powder for infiltration.

[0045] Step 3: The C / C composite material was modified by a reactive infiltration process. Five layers of graphite paper were laid on the inner wall of the graphite crucible, and a 10 mm thick layer of infiltration powder was laid on the bottom of the crucible. The porous C / C composite material was placed parallel to the upper layer of the infiltration powder. Powder was continued to be added until the sample was completely covered and 10 mm higher than the upper surface of the sample. During the powder addition process, the powder was ensured to be loose. After the powder was added, it was sealed with graphite paper and carbon felt in turn, and then the crucible was sealed.

[0046] Step 4: Place the sealed crucible in a graphite furnace for high-temperature treatment. The high-temperature heat treatment conditions are: temperature of 1700°C, furnace pressure of 10Pa, heating rate of 5°C / min, holding time of 3h, then power off and cool down. Take out the sample after it cools to room temperature with the furnace.

[0047] Step 5: The composite material obtained after the reaction infiltration was polished with 50 mesh, 800 mesh and 3000 mesh diamond grinding discs in turn to ensure that there were no obvious protrusions on the sample surface. The sample was then ultrasonically cleaned with deionized water for 5 times, each cleaning time was 60 minutes, and then placed in an electric blast drying oven at 80°C for 10 hours to obtain HfC x N y -SiC modified C / C composites.

[0048] The prepared composite material was subjected to X-ray diffraction analysis, such as Figure 2 As shown in Figure 2, it is shown that high melting point hafnium carbonitride is generated during the infiltration process. The SEM images of the prepared composite material are analyzed, as shown in Figure 2. Figure 3 As shown, from Figure 3 It can be seen that white HfC is formed on the surface of the sample x N y Phase and gray SiC phase. Therefore, it can be judged that this embodiment obtains HfC x N y -SiC modified C / C composites.

[0049] Example 2:

[0050] Step 1: Select a density of 1.7 g / cm 3 The C / C composite was processed into 10 mm cubic block specimens and polished using 50-, 800-, and 3000-mesh silicon carbide sandpaper to ensure a smooth, regular surface and no obvious defects during melt infiltration. The polished specimens were ultrasonically cleaned with deionized water three times for 60 minutes each. Subsequently, the block specimens were boiled at 350°C for 3 hours until no bubbles appeared on the surface, ensuring that the pores within the specimens were fully open. The specimens were then dried in an electric forced-air drying oven at 70°C for 6 hours before use.

[0051] Step 2: Mix HfSi2 and Si3N4 powders in a molar ratio of 4:1, place the powder mixture and zirconia grinding balls into a corundum ball mill with a ball-to-material ratio of 2:1, then seal the corundum ball mill, use a planetary ball mill at a speed of 400 rpm, ball mill for 6 hours, sieve, and then place in an electric blast drying oven at a temperature of 70°C and dry for 8 hours to obtain a uniformly mixed powder mixture, which is used as powder for infiltration.

[0052] Step 3: When modifying the C / C composite material using a reactive infiltration process, lay 4 layers of graphite paper on the inner wall of the graphite crucible, lay a 10 mm thick layer of infiltration powder on the bottom of the crucible, and place the porous C / C composite material parallel to the upper layer of the infiltration powder. Continue to add powder until the sample is completely covered and 10 mm higher than the upper surface of the sample. During the powder addition process, ensure that the powder is in a loose state. After the powder is added, seal it with graphite paper and carbon felt in turn, and then seal the crucible.

[0053] Step 4: Place the sealed crucible in a graphite furnace for high-temperature treatment. The high-temperature heat treatment conditions are: temperature of 1700°C, pressure in the furnace of 10Pa, heating rate of 5°C / min, and holding time of 3h. Then turn off the power and cool down. After the sample cools to room temperature with the furnace, take it out to obtain a modified carbon-carbon composite material.

[0054] Step 5: The composite material obtained after the reaction infiltration was polished with 50 mesh, 800 mesh and 3000 mesh diamond grinding discs in turn to ensure that there were no obvious protrusions on the sample surface. The sample was then ultrasonically cleaned with deionized water for 5 times, each cleaning time was 30 minutes, and then placed in an electric blast drying oven at 80°C for 12 hours to obtain HfC x N y -SiC modified C / C composites.

[0055] Example 3:

[0056] Step 1: Select a density of 1.2 g / cm 3 The 2.5DC / C composite material was processed into 10mm×10mm×10mm block specimens. These were then polished using 50-, 800-, and 3000-grit silicon carbide sandpaper to ensure a smooth, regular surface and no obvious defects during melt infiltration. The polished specimens were ultrasonically cleaned with deionized water three times, each lasting 60 minutes. Subsequently, the block specimens were boiled at 200°C for 4 hours until no bubbles appeared on the surface, ensuring that the pores within the specimens were fully open. The specimens were then dried in an electric forced-air drying oven at 70°C for 6 hours before use.

[0057] Step 2: Mix HfSi2 and Si3N4 powders in a molar ratio of 4:1, place the powder mixture and zirconia grinding balls into a corundum ball mill with a ball-to-material ratio of 2:1, then seal the corundum ball mill, use a planetary ball mill at a speed of 400 rpm, ball mill for 4 hours, sieve, and then place in an electric blast drying oven at a temperature of 70°C and dry for 8 hours to obtain a uniformly mixed powder mixture, which is used as powder for infiltration.

[0058] Step 3: Use the reactive infiltration process to modify the matrix of the C / C composite material. Lay 5 layers of graphite paper on the inner wall of the graphite crucible, lay 6 mm thick infiltration powder on the bottom of the crucible, and place the porous C / C composite material parallel to the upper layer of the infiltration powder. Continue to add powder until the sample is completely covered and 8 mm higher than the upper surface of the sample. During the powder addition process, ensure that the powder is in a loose state. After the powder is added, seal it with graphite paper and carbon felt in turn, and then seal the crucible.

[0059] Step 4: Place the sealed crucible in a graphite furnace for high-temperature treatment. The high-temperature heat treatment conditions are: temperature of 1900°C, Ar gas atmosphere in the furnace, heating rate of 10°C / min, holding time of 2h, then power off and cool down. Wait for the sample to cool to room temperature with the furnace and then take it out.

[0060] Step 5: The composite material obtained after the reaction infiltration was polished with 50 mesh, 800 mesh and 3000 mesh diamond grinding discs in turn to ensure that there were no obvious protrusions on the sample surface. The sample was then ultrasonically cleaned with deionized water for 5 times, each cleaning time was 30 minutes, and then placed in an electric blast drying oven at 80°C for 12 hours to obtain HfC x N y -SiC modified C / C composites.

[0061] Example 4:

[0062] Step 1: Select a density of 1.7 g / cm 3 The 2.5DC / C composite material was processed into 10mm×10mm×10mm block specimens. These were then polished using 50-, 800-, and 3000-mesh silicon carbide sandpaper to ensure a smooth, regular surface and no obvious defects during melt infiltration. The polished specimens were ultrasonically cleaned with deionized water three times, each lasting 30 minutes. Subsequently, the block specimens were boiled at 350°C for 3 hours until no bubbles appeared on the surface, ensuring that the pores within the specimens were fully open. The specimens were then dried in an electric forced-air drying oven at 70°C for 8 hours before use.

[0063] Step 2: Mix HfSi2 and Si3N4 powders in a molar ratio of 4:1, place the powder mixture and zirconia grinding balls into a corundum ball mill with a ball-to-material ratio of 2:1, then seal the corundum ball mill, use a planetary ball mill at a speed of 300 rpm, ball mill for 4 hours, sieve, and then place in an electric blast drying oven at a temperature of 70°C and dry for 10 hours to obtain a uniformly mixed powder mixture, which is used as powder for infiltration.

[0064] Step 3: Use the reactive infiltration process to modify the matrix of the C / C composite material. Lay 5 layers of graphite paper on the inner wall of the graphite crucible, lay 6 mm thick infiltration powder on the bottom of the crucible, and place the porous C / C composite material parallel to the upper layer of the infiltration powder. Continue to add powder until the sample is completely covered and 8 mm higher than the upper surface of the sample. During the powder addition process, ensure that the powder is in a loose state. After the powder is added, seal it with graphite paper and carbon powder in turn, and then seal the crucible.

[0065] Step 4: Place the sealed crucible in a graphite furnace for high-temperature treatment. The high-temperature heat treatment conditions are as follows: temperature of 1900°C, Ar gas atmosphere in the furnace, maintaining atmospheric pressure, heating rate of 4°C / min, holding time of 1 hour, then power off and cool down. Wait for the sample to cool to room temperature with the furnace and then take it out.

[0066] Step 5: The composite material obtained after the reaction infiltration was polished with 50 mesh, 800 mesh and 3000 mesh diamond grinding discs in turn to ensure that there were no obvious protrusions on the sample surface. The sample was then ultrasonically cleaned with deionized water for 5 times, each cleaning time was 40 minutes, and then placed in an electric blast drying oven at 80°C for 12 hours to obtain HfC x N y -SiC modified C / C composites.

[0067] Embodiment 5:

[0068] Step 1: Select a density of 1.1 g / cm 3 The 2.5DC / C composite material was processed into 10mm×10mm×10mm block specimens. These were then polished using 50-, 800-, and 3000-grit silicon carbide sandpaper to ensure a smooth, regular surface and no obvious defects during melt infiltration. The polished specimens were ultrasonically cleaned with deionized water five times, each lasting 30 minutes. Subsequently, the block specimens were boiled at 350°C for 3 hours until no bubbles appeared on the surface, ensuring that the pores within the specimens were fully open. The specimens were then dried in an electric forced-air drying oven at 80°C for 8 hours before use.

[0069] Step 2: Mix HfSi2 and Si3N4 powders in a molar ratio of 4:1, place the powder mixture and zirconia grinding balls into a corundum ball mill with a ball-to-material ratio of 2:1, then seal the corundum ball mill, use a planetary ball mill at a speed of 300 rpm, ball mill for 6 hours, sieve, and then place in an electric blast drying oven at a temperature of 70°C and dry for 10 hours to obtain a uniformly mixed powder mixture, which is used as powder for infiltration.

[0070] Step 3: Use the reactive infiltration process to modify the matrix of the C / C composite material. Lay 5 layers of graphite paper on the inner wall of the graphite crucible, lay 6 mm thick infiltration powder on the bottom of the crucible, and place the porous C / C composite material parallel to the upper layer of the infiltration powder. Continue to add powder until the sample is completely covered and 8 mm higher than the upper surface of the sample. During the powder addition process, ensure that the powder is in a loose state. After the powder is added, seal it with graphite paper and carbon felt in turn, and then seal the crucible.

[0071] Step 4: Place the sealed crucible in a graphite furnace for high-temperature treatment. The high-temperature heat treatment conditions are as follows: temperature of 2100°C, Ar gas atmosphere in the furnace, heating rate of 5°C / min, holding time of 1h, then power off and cool down. Wait for the sample to cool to room temperature with the furnace and then take it out.

[0072] Step 5: The composite material obtained after the reaction infiltration was polished with 50 mesh, 800 mesh and 3000 mesh diamond grinding discs in turn to ensure that there were no obvious protrusions on the sample surface. The sample was then ultrasonically cleaned with deionized water for 5 times, each cleaning time was 30 minutes, and then placed in an electric blast drying oven at 80°C for 12 hours to obtain HfC x N y -SiC modified C / C composites.

[0073] Example 6:

[0074] Step 1: Select a density of 1.7 g / cm 3 The 2.5DC / C composite material was processed into 10mm×10mm×10mm block specimens. These were then polished using 50-, 800-, and 3000-grit silicon carbide sandpaper to ensure a smooth, regular surface and no obvious defects during melt infiltration. The polished specimens were ultrasonically cleaned with deionized water three times, each for 60 minutes. Subsequently, the block specimens were boiled at 300°C for 3 hours until no bubbles appeared on the surface, ensuring that the pores within the specimens were fully open. The specimens were then dried in an electric forced-air drying oven at 80°C for 8 hours before use.

[0075] Step 2: Mix HfSi2 and Si3N4 powders in a molar ratio of 1:1, place the powder mixture and zirconia grinding balls into a corundum ball mill with a ball-to-material ratio of 2:1, then seal the corundum ball mill, use a planetary ball mill at a speed of 400 rpm, ball mill for 4 hours, sieve, and then place in an electric blast drying oven at a temperature of 70°C and dry for 10 hours to obtain a uniformly mixed powder mixture, which is used as powder for infiltration.

[0076] Step 3: Use the reactive infiltration process to modify the matrix of the C / C composite material. Lay 5 layers of graphite paper on the inner wall of the graphite crucible, lay 4 mm thick infiltration powder on the bottom of the crucible, and place the porous C / C composite material parallel to the upper layer of the infiltration powder. Continue to add powder until the sample is completely covered and 8 mm higher than the upper surface of the sample. During the powder addition process, ensure that the powder is in a loose state. After the powder is added, seal it with graphite paper and carbon felt in turn, and then seal the crucible.

[0077] Step 4: Place the sealed crucible in a graphite furnace for high-temperature treatment. The high-temperature heat treatment conditions are as follows: temperature of 2100°C, Ar gas atmosphere in the furnace, heating rate of 5°C / min, holding time of 1h, then power off and cool down. Wait for the sample to cool to room temperature with the furnace and then take it out.

[0078] Step 5: The composite material obtained after the reaction infiltration was polished with 50 mesh, 800 mesh and 3000 mesh diamond grinding discs in turn to ensure that there were no obvious protrusions on the sample surface. The sample was then ultrasonically cleaned with deionized water for 3 times, each cleaning time was 60 minutes, and then placed in an electric blast drying oven at 80°C for 12 hours to obtain HfC x N y -SiC modified C / C composites.

[0079] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A HfC x N y -A method for preparing a SiC-modified C / C composite material, characterized in that: include: Pre-treating the C / C composite material to obtain a C / C preform for infiltration; Mix HfSi2 and Si3N4 powders and dry them to obtain powder for infiltration; The C / C preform for infiltration is placed parallel to the upper layer of the infiltration powder, and the infiltration powder is continued to be added until the C / C preform for infiltration is completely covered and higher than the upper surface of the C / C preform for infiltration. After sealing, it is modified by the reaction infiltration process at high temperature to obtain C / C-HfC x N y -SiC composite materials; C / C-HfC x N y -SiC composite material is polished, cleaned and dried to obtain HfC x N y -SiC modified C / C composites.

2. A HfC according to claim 1 x N y -A method for preparing a SiC-modified C / C composite material, characterized in that: The pretreatment includes grinding, cleaning, boiling and drying.

3. A HfC according to claim 2 x N y -A method for preparing a SiC-modified C / C composite material, characterized in that: The boiling treatment temperature is 100-350° C., and the treatment time is 1-6 hours.

4. A HfC according to claim 2 x N y -A method for preparing a SiC-modified C / C composite material, characterized in that: The drying treatment temperature is 70° C., and the treatment time is 6 to 10 hours.

5. A HfC according to claim 1 x N y -A method for preparing a SiC-modified C / C composite material, characterized in that: The molar ratio of the HfSi2 to Si3N4 powders is (1-4):(1-4).

6. A HfC according to claim 1 x N y -A method for preparing a SiC-modified C / C composite material, characterized in that: The HfSi2 and Si3N4 powders are mixed by ball milling. During the ball milling process, the ball-to-material ratio is 2:1, the rotation speed is 200-500 rpm, and the ball milling time is 4-6 hours.

7. A HfC according to claim 1 x N y -A method for preparing a SiC-modified C / C composite material, characterized in that: The drying temperature of the powder for infiltration is 60-100° C., and the drying time is 8-12 hours.

8. A HfC according to claim 1 x N y -A method for preparing a SiC-modified C / C composite material, characterized in that: The modification treatment conditions are: in an Ar or N2 inert atmosphere protection environment or a vacuum environment with a vacuum degree of 1 to 100 Pa, a temperature of 1600 to 2100°C, a heating rate of 4 to 10°C / min, and a holding time of 0.5 to 3h.

9. A HfC according to claim 1 x N y -A method for preparing a SiC-modified C / C composite material, characterized in that: The HfC x N y The drying temperature of the SiC-modified C / C composite material is 60 to 100° C., and the drying time is 6 to 12 hours.

10. HfC prepared by the preparation method according to any one of claims 1 to 9 x N y -SiC modified C / C composites.

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