Transition metal carbonitride ceramic matrix modified C / C composite material and preparation method thereof

Abstract

The invention belongs to the technical field of composite materials, and discloses a transition metal carbonitride ceramic matrix modified C / C composite material and a preparation method thereof.The preparation method comprises the steps that a porous C / C prefabricated body is pretreated, open pores in the porous C / C prefabricated body are opened, and the porous prefabricated body is obtained; introducing a nitrogen source into the porous preform through a precursor impregnation pyrolysis process to obtain a porous nitrogenous substance C / C preform; wherein the adopted impregnation liquid is a homogeneous polysilazane solution, the homogeneous polysilazane solution comprises the components of polysilazane and a powder material, and the powder material adopts micro-nano silicon nitride or transition metal disilicide; and performing matrix modification on the porous nitrogenous substance C / C preform through powder infiltration and a reactive infiltration process to obtain the transition metal carbonitride ceramic matrix modified C / C composite material. A transition metal carbonitride ceramic matrix is introduced into the C / C composite material through the RMI and PIP combined technology, and the ablation resistance and the scouring resistance of the material are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and particularly relates to a transition metal carbonitride ceramic matrix modified C / C composite material and a preparation method thereof. Background Technique

[0002] C / C composite materials have the advantages of light weight, high strength, and the mechanical properties at high temperature increasing instead of decreasing. However, the high oxidation activity severely limits the application of C / C composite materials in high-temperature fields. The ceramic matrix modified C / C composite materials inherit the characteristics of ceramics such as oxidation resistance and ablation resistance, overcome the disadvantages of large intrinsic brittleness and poor reliability of ceramics, have a metal-like fracture behavior, and are not prone to catastrophic fracture. They are ideal materials for thermal protection systems and are widely used in hot-end components in the aerospace field such as the nose cones and rudder wings of aircraft and the nozzles of rocket engines.

[0003] Compared with nitride and boride ultra-high temperature ceramics, carbide ultra-high temperature ceramics have a higher melting point and better compatibility with C / C composite materials. In addition, the large non-stoichiometric ratio range enables the performance to be adjustable. Therefore, carbide ultra-high temperature ceramics are commonly used as ablation-resistant components to modify the matrix of C / C composite materials to achieve high-temperature thermal protection. Since the oxidation process is accompanied by the generation and release of CO and CO2 gases, it is often difficult for carbide ultra-high temperature ceramics to form a dense oxide layer. To meet the requirements of hypersonic aircraft flying across the atmosphere and long-term service in the atmosphere, it is necessary to further improve the temperature resistance, oxidation resistance, erosion resistance, and structural toughness of carbide ultra-high temperature ceramics, so that the thermal protection components can withstand complex and diverse ultra-high temperature impact processes. Re-phasing and diversification are common strategies to improve the performance of ultra-high temperature ceramics (UHTCs). By introducing a second phase that can form a dense oxide layer or forming a single-phase multi-component ceramic solid solution, the oxidation and ablation resistance of UHTCs in the original service temperature range can be significantly improved, but it has little effect on improving the temperature resistance and erosion resistance of the materials.

[0004] Research findings show that introducing nitrogen into the anion sublattice can increase the melting point of ultra-high temperature carbide ceramics. In the first literature, American scholars QiJun Hong et al. [Hong Q J. Prediction of the material with highest known melting point from ab initio molecular dynamics calculations, Physical Review B, 2015, 92:020104.] predicted through first-principles molecular dynamics simulation calculations and regression analysis that the Hf-C-N alloy with 20 at.% nitrogen and 27 at.% carbon has a melting point much higher than that of (Ta4Hf)C (3942 °C), raising the melting point record by 200 °C. In the second literature, Ushakov S V et al. [Ushakov S V, Navrotsky A, Hong Q J, et al. Carbides and nitrides of zirconium and hafnium[J]. Materials, 2019, 12(17): 2728.] verified that the HfC 0.75 N 0.22 phase has the highest known melting entropy of 150 KJ / mol currently.

[0005] In addition to significantly improving the temperature resistance of existing ultra-high temperature ceramics, the research also pointed out that in hafnium carbonitride (abbreviation: HfC x N y ), the more electronegative nitrogen tends to preferentially adsorb oxygen, increasing the absorption energy barrier of hafnium atoms, thereby improving the oxidation resistance of hafnium carbide (abbreviation: HfC). The introduction of nitrogen atoms changes the electronic structure around adjacent carbon atoms, and the special bond state improves the hardness and toughness of hafnium carbide. This makes HfC x N y have higher temperature resistance, better oxidation and erosion resistance, and structural toughness than hafnium carbide. Therefore, HfC x N y ceramic matrix modified C / C composites are a powerful support for the breakthrough progress of hypersonic vehicles and are also the key to realizing the wider application of C / C composites and ultra-high temperature ceramics. The reaction infiltration process (RMI) is the main technical means for matrix modification of C / C composites due to its technical advantages of short preparation cycle and high densification degree. However, limited by the nitrogen source, it is difficult to introduce the HfC x N y ablation-resistant component into the interior of C / C composites through a simple reaction infiltration process. Summary of the Invention

[0006] To solve the problems existing in the prior art, the purpose of the present invention is to provide a transition metal carbonitride ceramic matrix modified C / C composite material and a preparation method thereof. The present invention introduces a transition metal carbonitride ceramic matrix inside the C / C composite material through a reactive melt infiltration (RMI) combined with a precursor infiltration and pyrolysis (PIP) process to improve the ablation resistance and erosion resistance of the material.

[0007] To achieve the above purpose, the technical scheme adopted by the present invention is as follows: A preparation method of a transition metal carbonitride ceramic matrix modified C / C composite material includes the following processes: Pre-treat the porous C / C preform to open the open pores in the porous C / C preform to obtain a porous preform; Introduce a nitrogen source inside the porous preform through a precursor infiltration and pyrolysis process to obtain a porous nitrogen-containing C / C preform; in the precursor infiltration and pyrolysis process, the impregnation solution used is a homogeneous polysilazane solution, and the components of the homogeneous polysilazane solution include polysilazane and a powder material, and the powder material uses micro-nano silicon nitride or transition metal disilicide; Perform matrix modification on the porous nitrogen-containing C / C preform through infiltration powder and reactive melt infiltration processes to obtain the transition metal carbonitride ceramic matrix modified C / C composite material.

[0008] Preferably, the porous C / C preform is a preform processed from a 2.5D C / C composite material with a density of 0.8 - 1.3 g / cm 3 ; or the porous C / C preform is a preform processed from a 3D C / C composite material; The shape of the porous C / C preform is a cube or a cylinder. When the shape of the porous C / C preform is a cube, the side length is 8 - 12 mm; when the shape of the porous C / C preform is a cylinder, the bottom diameter of the porous C / C preform is 28 - 30 mm and the height is 2 - 4 mm.

[0009] Preferably, pre-treating the porous C / C preform to open the open pores in the porous C / C preform includes: Grind the porous C / C preform to make the surface of the porous C / C preform smooth and shiny, then ultrasonically clean the ground porous C / C preform with deionized water, and the number of cleaning times is 3 - 5 times, and the cleaning time for each time is 30 - 60 min; subsequently, perform boiling treatment on the porous C / C preform at 100 - 350 °C for 1 - 6 h until no bubbles emerge on the surface of the porous C / C preform, and then dry the porous C / C preform at 60 - 100 °C for 6 - 12 h to obtain the porous preform.

[0010] Preferably, a nitrogen source is introduced into the porous preform by a precursor impregnation pyrolysis process, including: Impregnation process: The porous preform is subjected to vacuum impregnation in a homogeneous polysilazane solution, and then the porous preform is dried at 150-180 °C for 2-10 h; the impregnation process is repeated 2-5 times to obtain a first sample; Pyrolysis process: The first sample is subjected to high-temperature pyrolysis to convert the organic precursor into an inorganic ceramic, obtaining a second sample; The impregnation process and the pyrolysis process are repeated 1-3 times for the second sample to obtain the porous nitrogen-containing C / C preform.

[0011] Preferably, the preparation process of the homogeneous polysilazane solution includes: Powder materials are added to the polysilazane solution and mixed evenly to obtain the homogeneous polysilazane solution; wherein, 0.01-2 g of powder materials are added corresponding to every 50-70 ml of the polysilazane solution.

[0012] Preferably, the transition metal in the transition metal disilicide is at least one of Hf, Zr, Ta, Ni, and Ti.

[0013] Preferably, the pyrolysis process specifically includes: Nitrogen is introduced into the equipment used in the pyrolysis process for gas washing operation to remove oxygen in the furnace; After the gas washing is completed, nitrogen is introduced into the equipment used in the pyrolysis process, and then the temperature is raised to 280-350 °C at a rate of 2-10 °C / min and held for 1-3 h for solidification reaction; After the solidification reaction is completed, the temperature is raised to 900-1400 °C at a rate of 2-10 °C / min and held for 1-3 h to convert the organic precursor into an inorganic ceramic, and then the temperature is lowered to 300 °C at a rate of 2-10 °C / min, and then cooled to room temperature with the furnace to obtain a second sample.

[0014] Preferably, the process of matrix modification of the porous nitrogen-containing C / C preform by infiltrating powder materials and reactive infiltration process includes a high-temperature treatment process. During the high-temperature treatment, the pressure is controlled at 5 Pa-0.1 MPa, heated from room temperature to 1700-2100 °C at a heating rate of 4-10 °C / min, and held for 0.5-2 h, and then cooled with the furnace to obtain the transition metal carbonitride ceramic matrix modified C / C composite; Among them, the infiltrated powder materials are the same as the powder materials used in the precursor impregnation pyrolysis process.

[0015] Preferably, the process of matrix modification of the porous nitrogen-containing C / C preform by infiltrating powder materials and reactive infiltration process further includes: Preparation: Clean the porous nitrogen-containing C / C preform; Lay 3 - 5 layers of graphite paper on the inner wall of the graphite crucible, and lay 5 - 15 mm thick infiltration powder on the bottom of the crucible. Place the cleaned porous nitrogen-containing C / C preform parallel to the direction of the wire mesh layer on the infiltration powder laid on the bottom of the crucible. Then continue to add infiltration powder to completely cover the porous nitrogen-containing C / C preform and be 5 - 15 mm higher than the upper surface of the porous nitrogen-containing C / C preform, and then perform sealing treatment; Then place the graphite crucible in a graphite furnace for the high-temperature treatment process.

[0016] The present invention also provides a transition metal carbonitride ceramic matrix modified C / C composite material, and the transition metal carbonitride ceramic matrix modified C / C composite material is prepared by the preparation method as described above in the present invention.

[0017] Advantages of the present invention: In the preparation method of the transition metal carbonitride ceramic matrix modified C / C composite material of the present invention, a polysilazane (PSN) solution with wettability and better filling effect on the porous C / C preform is used as the nitrogen source. Compared with slurry suction filtration, through one or two PIP (precursor infiltration pyrolysis) cycles, the uniform distribution of nitrogen-containing substances inside the porous C / C preform can be achieved, solving the problem of the source of nitrogen during the formation of ceramic phases (such as HfC x N y ). The reaction infiltration process of ceramic matrix modified C / C composite materials with ceramic phases (such as HfC x N y ) is realized, bringing more possibilities for the low-cost and short-cycle preparation of high-performance ceramic matrix modified C / C composite materials. The preparation method of the present invention has a short preparation period, that is, the present invention adopts a process combining reaction melt infiltration (RMI) and precursor infiltration pyrolysis (PIP), uses polysilazane (PSN) as the nitrogen source, and uses transition metal disilicide as the infiltration agent. Compared with the PIP process, the types of precursors required are less, and it is more friendly to the environment and human body. The number of infiltration pyrolysis cycles is less, and the preparation period is shorter; compared with the RMI process of mixing nitrogen-containing substances in the infiltration powder, introducing nitrogen-containing substances into the pores in advance can improve the infiltration effect of the melt.

[0018] The obtained transition metal carbonitride ceramic matrix modified C / C composite material of the present invention has great application value. The present invention combines ceramic phases (such as HfC x N yIntroduced into the interior of the C / C composite material matrix, it can better improve the service life of composite material components in environments with high heat flux density, high-pressure gas flow, and high-speed particle erosion, meet the requirements of hypersonic vehicles for flying across the atmosphere and long-term service within the atmosphere, etc., and has great space strategic significance. Brief Description of the Drawings

[0019] Figure 1 It is a process flow diagram of the preparation method of the transition metal carbonitride ceramic matrix modified C / C composite material in the embodiment of the present invention; Figure 2(a) is the surface SEM image of the HfC x N y ceramic matrix modified C / C composite material prepared in Embodiment 1 of the present invention; Figure 2(b) is the SEM image of region 1 in Figure 2(a); Figure 2(c) is the SEM image of region 2 in Figure 2(a); Figure 3 It is the XRD pattern of the HfC x N y ceramic matrix modified C / C composite material prepared in Embodiment 1 of the present invention; Figure 4 It is the macroscopic photograph of the surface of the HfC x N y ceramic matrix modified C / C composite material after plasma ablation; Figure 5(a) is the high-magnification SEM image of the HfC x N y ceramic matrix modified C / C composite material prepared in Embodiment 2 of the present invention; Figure 5(b) is the EDS energy spectrum image of the HfC x N y ceramic matrix modified C / C composite material prepared in Embodiment 2 of the present invention; Figure 6 It is the SEM image of the surface of the composite material prepared in Embodiment 3 of the present invention. Detailed Embodiments

[0020] Next, in combination with the drawings and the embodiments of the present invention, the present invention will be clearly and completely described. The described embodiments are only a part of the embodiments of the present invention, not all of the embodiments.

[0021] The present invention improves the oxidation resistance and ablation resistance of C / C composites by introducing transition metal carbonitride ceramics through anion solid solution, and improves the erosion resistance of carbide ultra-high temperature ceramic matrix modified C / C composites. Specifically, the present invention introduces a nitrogen source inside the C / C preform through the precursor infiltration pyrolysis process (PIP), and completes the solid solution of carbon and nitrogen elements during the infiltration of molten materials such as (HfSi2), in-situ generating HfCxNy ceramic phases, providing an option for the low-cost and short-cycle preparation of high-performance ceramic matrix modified C / C composites.

[0022] See Figure 1 , a preparation method of a transition metal carbonitride ceramic matrix modified C / C composite of the present invention, comprising the following steps: Step 1: Select a 2.5D C / C composite with a density of 0.8~1.3 g / cm 3 , process it into preforms with dimensions of 10×10×10 mm (cubic shape) and Φ30×3 mm (cylindrical shape), or process the preforms using 3D C / C composites; then use silicon carbide sandpaper to polish the preforms to ensure that there are no obvious defects in the preforms during reactive melt infiltration and the surface is smooth and clean. Then use deionized water to ultrasonically clean the polished preforms, with the number of cleaning times being 3~5 times, the cleaning time for each time being 30~60 min, and replacing the cleaning solution after each cleaning. Subsequently, boil the porous preforms at 100~350 °C for 1~6 h until no bubbles emerge from the surface of the preforms, ensuring that the open pores inside the preforms are completely opened. Weigh the wet weight and floating weight of the preforms using the Archimedes drainage method, and then place the specimens in an electrothermal blast drying oven at a temperature of 60~100 °C and dry them for 6~12 h, and weigh their weights.

[0023] Step 2: Use 50~70 ml of polysilazane (PSN) solution as the precursor. Optionally, add 0.01~2 g of micro-nano silicon nitride (Si3N4) or transition metal disilicide MeSi2 (Me is a mixture of one or more of Hf, Zr, Ta, Ni, Ti) powder to the PSN solution to promote nucleation and the formation of transition metal carbonitrides. After stirring evenly, a homogeneous PSN solution is obtained. Then immerse the porous preforms obtained in Step 1 in the homogeneous PSN solution and vacuum impregnate them, and then put them in an oven at 150~180 °C and dry them for 2~10 h. Repeat the impregnation process 2~5 times to obtain a first sample.

[0024] Step 3: Put the first sample obtained in Step 2 into a graphite box, and then place it in the central section of a tube furnace. Under a nitrogen atmosphere, perform high-temperature pyrolysis. Before the temperature rise for high-temperature pyrolysis, first pass nitrogen for purging operation to remove oxygen in the tube furnace and prevent the occurrence of side reactions. After the purging is completed, pass nitrogen, and the temperature in the furnace is raised to 280 - 350 °C at a rate of 2 - 10 °C / min, and keep it warm for 1 - 3 h for curing reaction. After the curing reaction is completed, then raise the temperature to 900 - 1400 °C at a rate of 2 - 10 °C / min, and keep it warm for 1 - 3 h to achieve the complete conversion of the organic precursor to inorganic ceramic. Then, cool it to 300 °C at a rate of 2 - 10 °C / min, and then cool it in the furnace to room temperature. Repeat the impregnation pyrolysis steps (i.e., Step 2 to Step 3) 1 - 3 times to obtain a porous nitrogen-containing C / C composite material.

[0025] Step 4: Clean the porous nitrogen-containing C / C composite material obtained in Step 3, and then use the reactive infiltration process to modify the matrix of the cleaned porous nitrogen-containing C / C composite material. The specific process is as follows: Lay 3 - 5 layers of graphite paper on the inner wall of a graphite crucible, and lay 5 - 15 mm thick infiltration powder (such as HfSi2) on the bottom of the crucible. Place the porous nitrogen-containing C / C composite material parallel to the direction of the wire mesh layer on the infiltration powder laid on the bottom of the graphite crucible. Continue to add infiltration powder until the porous nitrogen-containing C / C composite material is completely covered and is 5 - 15 mm higher than the upper surface of the porous nitrogen-containing C / C composite material. Seal the porous nitrogen-containing C / C preform and the infiltration powder with graphite paper and carbon felt, and then seal the graphite crucible.

[0026] Step 5: Place the sealed graphite crucible in a graphite furnace for high-temperature treatment. Among them, the high-temperature heat treatment conditions are as follows: the temperature is 1700 - 2100 °C, the pressure in the furnace is 5 Pa - 0.1 MPa, the heating rate is 4 - 10 °C / min, the holding time is 0.5 - 2 h. After the holding is completed, cut off the power supply for cooling. Wait for the sample to cool in the furnace to room temperature and then take it out to obtain the transition metal carbonitride ceramic matrix modified C / C composite material of the present invention.

[0027] Example 1 The preparation method of the transition metal carbonitride ceramic matrix modified C / C composite material in this example includes the following steps: Step 1: Select one with a density of 1.0 g / cm 3For the 2.5D C / C composite material, it is processed into a preform with dimensions of 10×10×10 mm (cubic shape). The preform is polished using silicon carbide sandpaper to ensure no obvious defects during reactive melt infiltration and the surface is smooth and shiny. The polished preform is ultrasonically cleaned with deionized water 5 times, with each cleaning time being 40 min. Subsequently, at 300 °C, the porous preform is boiled for 4 h until no bubbles emerge from the surface of the preform, ensuring that the open pores inside the preform are completely opened. The wet weight and floating weight of the preform are measured using the Archimedes drainage method. Then the preform is placed in an electrothermal blast drying oven at 70 °C and dried for 10 h, and its weight is measured.

[0028] Step 2: Using 60 ml of polysilazane (PSN) solution as the precursor, 0.5 g of micro-nano HfSi2 powder is added to the PSN solution to promote nucleation and the formation of HfC x N y After stirring evenly, the porous preform treated in Step 1 is immersed in the homogeneous PSN solution and vacuum impregnated, and then placed in an oven at 160 °C and dried for 4 h. The impregnation step is repeated three times to obtain the first sample.

[0029] Step 3: The first sample obtained in Step 2 is placed in a graphite box and then placed in the central section of a tube furnace. High-temperature pyrolysis is carried out in a nitrogen atmosphere. Before the high-temperature pyrolysis heating, nitrogen is first passed for purging operation to remove the oxygen in the tube furnace and prevent side reactions. After the purging is completed, nitrogen is passed, and the temperature in the furnace is raised to 300 °C at a rate of 5 °C / min and held for 2 h for the curing reaction. After the curing reaction is completed, the temperature is raised to 1300 °C at a rate of 3 °C / min and held for 2 h to achieve the complete conversion of the organic precursor to the inorganic ceramic. Then the temperature is lowered to 300 °C at a rate of 3 °C / min and then cooled to room temperature with the furnace. The impregnation and pyrolysis steps (i.e., Step 2 to Step 3) are repeated 2 times to obtain the porous nitrogen-containing C / C composite material.

[0030] Step 4: Clean the porous nitrogen-containing C / C composite obtained in Step 3, and then perform matrix modification on the cleaned porous nitrogen-containing C / C composite by reactive melt infiltration. The specific process is as follows: Lay 4 layers of graphite paper on the inner wall of the graphite crucible, lay 10 mm thick HfSi2 infiltration powder on the bottom of the crucible, place the porous nitrogen-containing C / C composite parallel to the direction of the wire mesh layer on the infiltration powder laid on the bottom of the graphite crucible, continue to add HfSi2 infiltration powder until the porous nitrogen-containing C / C composite is completely covered and is 10 mm higher than the upper surface of the porous nitrogen-containing C / C composite, and seal the porous nitrogen-containing C / C composite and the HfSi2 infiltration powder with graphite paper and carbon felt, and then seal the graphite crucible.

[0031] Step 5: Place the sealed graphite crucible in a graphite furnace for high-temperature treatment. Among them, the high-temperature heat treatment conditions are as follows: the temperature is 1850 °C, the pressure in the furnace is 10 Pa, the heating rate is 4 °C / min, the holding time is 1 h, after the holding is completed, cut off the power supply to cool down, and wait for the sample to cool to room temperature with the furnace and then take it out to obtain HfC x N y ceramic matrix modified C / C composite.

[0032] Analyze the SEM images of the surface of the composite material prepared in this example. As shown in Figures 2(a)-2(c), it can be seen that the surface of the sample can be divided into an un-dense gray area and a dense white area. According to the X-ray diffraction pattern analysis, as Figure 3 shown and combined with Table 1 and the EDS energy spectrum element analysis, Table 1 is the elemental content percentage table of spot 1 and spot 2 in Figure 2(b) and spot 3 in Figure 2(c): Table 1

[0033] It can be seen that in Figures 2(b) and 2(c), the dense white area is mainly the HfC x N y ceramic phase, and the un-dense gray area is composed of the white HfC x N y ceramic phase and the gray hafnium silicide phase. In summary, the HfC x N y ceramic matrix modified C / C composite is obtained in this example. Perform Ar-H2 system plasma ablation test on the prepared HfC x N y ceramic matrix modified C / C composite. After ablation for 30 s at a power of 35 kW, a white oxide film is formed on the surface of the sample. As Figure 4 shown, the linear ablation rate is 0.014 mm / s.

[0034] Example 2 The preparation method of the transition metal carbonitride ceramic matrix modified C / C composite material in this example includes the following steps: Step 1: Select a 2.5D C / C composite material with a density of 1.1 g / cm 3 . Process it into a preform with dimensions of 10×10×10 mm (cubic shape). Use silicon carbide sandpaper to polish the preform to ensure that there are no obvious defects during reactive melt infiltration and the surface is regular and smooth. Use deionized water to ultrasonically clean the polished preform 5 times, with each cleaning time being 25 min. Subsequently, boil the porous preform at 280°C for 4 h until no bubbles emerge from the surface of the preform, ensuring that the open pores in the preform are completely opened. Weigh the wet weight and floating weight of the preform using the Archimedes drainage method, and then place the preform in an electrothermal blast drying oven at 70°C and dry it for 10 h, and weigh its weight.

[0035] Step 2: Use 70 ml of polysilazane (PSN) solution as the precursor. Add 0.5 g of micro-nano HfSi2 powder to the PSN solution to promote nucleation and the formation of HfC x N y . After stirring evenly, immerse the porous preform treated in Step 1 in the homogeneous PSN solution and carry out vacuum impregnation, and then put it into an oven at 180°C and dry it for 4 h. Repeat the impregnation step three times to obtain the first sample.

[0036] Step 3: Put the first sample obtained in Step 2 into a graphite box, and then place it in the central section of a tube furnace. Carry out high-temperature pyrolysis in a nitrogen environment. Before the high-temperature pyrolysis heating-up, first conduct a purging operation with nitrogen to remove the oxygen in the tube furnace to prevent side reactions. After the purging is completed, introduce nitrogen. The temperature in the furnace is raised to 300°C at a rate of 4°C / min and held for 2 h for curing reaction. After the curing reaction is completed, the temperature is then raised to 1100°C at a rate of 3°C / min and held for 2.5 h to achieve the complete conversion of the organic precursor to the inorganic ceramic. Then, the temperature is lowered to 300°C at a rate of 3°C / min, and then cooled to room temperature with the furnace. Repeat the impregnation and pyrolysis steps (i.e., Step 2 to Step 3) 2 times to obtain a porous nitrogen-containing C / C composite material.

[0037] Step 4: Clean the porous nitrogen-containing C / C composite obtained in Step 3, and then use the reactive infiltration process to modify the matrix of the cleaned porous nitrogen-containing C / C composite. The specific process is as follows: Lay 5 layers of graphite paper on the inner wall of the graphite crucible, lay 15 mm thick HfSi2 infiltration powder on the bottom of the crucible, place the porous nitrogen-containing C / C composite parallel to the direction of the wire mesh layer on the infiltration powder laid on the bottom of the graphite crucible, and continue to add HfSi2 infiltration powder until the porous nitrogen-containing C / C composite is completely covered and is 10 mm higher than the upper surface of the sample. Seal the porous nitrogen-containing C / C composite and the HfSi2 infiltration powder with graphite paper and carbon felt, and then seal the graphite crucible.

[0038] Step 5: Place the sealed graphite crucible in a graphite furnace for high-temperature treatment. Among them, the high-temperature heat treatment conditions are as follows: the temperature is 1850 °C, the pressure in the furnace is 5 Pa, the heating rate is 5 °C / min, the holding time is 1.5 h. After the holding is completed, cut off the power supply to cool down. Wait for the sample to cool to room temperature with the furnace and then take it out to obtain HfC x N y ceramic matrix modified C / C composite.

[0039] Combined with the high-magnification SEM image analysis of the cross-section and the EDS elemental energy spectrum analysis, the phase characterization of the near-surface area of the composite material is carried out. As shown in Figure 5(a) and Figure 5(b), it can be seen that the HfC x N y ceramic matrix modified C / C composite sample in the near-surface area inside the sample is mainly composed of a dense HfC x N y ceramic phase. The change in the relative content of each element between regions leads to the difference in light and dark contrast in different regions in the SEM image. That is, the HfC x N y ceramic matrix modified C / C composite is obtained in this example.

[0040] Example 3 The preparation method of the transition metal carbonitride ceramic matrix modified C / C composite in this example includes the following steps: Step 1: Select a density of 0.9 g / cm 3For the 2.5D C / C composite material, it is processed into a preform with dimensions of Φ30×3 mm (cylindrical shape). The preform is polished using silicon carbide sandpaper to ensure no obvious defects during reactive melt infiltration, and the surface is in a regular and smooth state. The polished preform is ultrasonically cleaned with deionized water 4 times, with each cleaning time being 40 min. Subsequently, at 320 °C, the porous preform is boiled for 3 h until no bubbles emerge from the surface of the preform, ensuring that the open pores of the preform are completely opened. The wet weight and floating weight of the preform are measured using the Archimedes drainage method. Then, the preform is placed in an electrothermal blast drying oven at 70 °C and dried for 10 h, and its weight is measured.

[0041] Step 2: Use 50 ml of polysilazane (PSN) solution as the precursor, add 0.5 g of micro-nano HfSi2 powder to the PSN solution to promote nucleation and the formation of HfC x N y After stirring evenly, the porous preform treated in Step 1 is immersed in the homogeneous PSN solution and vacuum impregnated, and then placed in an oven at 170 °C and dried for 3 h. The impregnation step is repeated three times to obtain the first sample.

[0042] Step 3: The first sample obtained in Step 2 is placed in a graphite box and then placed in the central section of a tube furnace. High-temperature pyrolysis is carried out under a nitrogen atmosphere. Before the high-temperature pyrolysis heating, first, nitrogen is passed for purging operation to remove oxygen in the tube furnace and prevent side reactions. After the purging is completed, nitrogen is passed. The temperature in the furnace is raised to 350 °C at a rate of 4 °C / min and held for 2 h for the curing reaction. After the curing reaction is completed, the temperature is raised to 1000 °C at a rate of 3 °C / min and held for 3 h to achieve the complete conversion of the organic precursor to the inorganic ceramic. Then, the temperature is lowered to 300 °C at a rate of 3 °C / min, and then cooled to room temperature with the furnace. The impregnation and pyrolysis steps (i.e., Step 2 to Step 3) are repeated 2 times to obtain a porous nitrogen-containing C / C composite material.

[0043] Step 4: The porous nitrogen-containing C / C composite material obtained in Step 3 is cleaned, and then the matrix of the cleaned porous nitrogen-containing C / C composite material is modified using the reactive melt infiltration process. The specific process is as follows: Lay 3 layers of graphite paper on the inner wall of a graphite crucible, lay 12 mm thick HfSi2 infiltration powder on the bottom of the crucible. Place the porous nitrogen-containing C / C composite material parallel to the direction of the wire mesh layer on the infiltration powder laid on the bottom of the graphite crucible. Continue to add HfSi2 infiltration powder until the porous nitrogen-containing C / C composite material is completely covered and is 8 mm higher than the upper surface of the sample. Seal the porous nitrogen-containing C / C composite material and the HfSi2 infiltration powder with graphite paper and carbon felt, and then seal the graphite crucible.

[0044] Step 5: Place the sealed graphite crucible in a graphite furnace for high-temperature treatment. The high-temperature heat treatment conditions are as follows: the temperature is 1900 °C, an Ar atmosphere is introduced into the furnace, the atmospheric pressure is maintained, the heating rate is 4 °C / min, the holding time is 1 h. After the holding is completed, power is cut off for cooling. Wait for the sample to cool to room temperature with the furnace and then take it out to obtain HfC x N y ceramic matrix modified C / C composite material.

[0045] Analyze the SEM images of the surface of the prepared composite material, as Figure 6 shown. It can be seen that an HfC x N y ceramic phase is formed on the surface of the sample, and there are silicide residues on the surface. Table 2 is the Figure 6 element content percentage table of spot 1 and spot 2 in Table 2

[0046] It can be seen from Table 2 that the HfC x N y ceramic matrix modified C / C composite material is obtained in this example.

[0047] Based on the present invention, more extensive preparation and performance improvement schemes for transition metal carbonitride modified carbon-carbon composite materials can be designed. Therefore, the development prospect of the present invention is very promising, and the economic and social benefits are very prominent.

[0048] Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0049] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: still can modify the specific implementation manners of the present invention or make equivalent substitutions, and any modification or equivalent substitution without departing from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A preparation method of a transition metal carbonitride ceramic matrix modified C / C composite material, characterized in that, It includes the following processes: Pre-treat the porous C / C preform to open the open pores in the porous C / C preform, obtaining a porous preform; Introduce a nitrogen source into the interior of the porous preform through the precursor infiltration pyrolysis process, obtaining a porous nitrogen-containing C / C preform; in the precursor infiltration pyrolysis process, the impregnation solution used is a homogeneous polysilazane solution, and the components of the homogeneous polysilazane solution include polysilazane and a powder material, and the powder material is micro-nano silicon nitride or transition metal disilicide; Perform matrix modification on the porous nitrogen-containing C / C preform through infiltrating powder and reactive infiltration processes, obtaining the transition metal carbonitride ceramic matrix modified C / C composite.

2. The preparation method of a transition metal carbonitride ceramic matrix modified C / C composite material according to claim 1, characterized in that, The porous C / C preform is a preform processed from a 2.5D C / C composite material with a density of 0.8 to 1.3 g / cm 3 ; or, the porous C / C preform is a preform processed from a 3D C / C composite material; The shape of the porous C / C preform is a cube or a cylinder. When the shape of the porous C / C preform is a cube, the side length is 8-12 mm; when the shape of the porous C / C preform is a cylinder, the bottom diameter of the porous C / C preform is 28-30 mm and the height is 2-4 mm.

3. The preparation method of a transition metal carbonitride ceramic matrix modified C / C composite material according to claim 1, characterized in that, Pre-treat the porous C / C preform to open the open pores in the porous C / C preform, including: Grind the porous C / C preform to make the surface of the porous C / C preform smooth and shiny, then ultrasonically clean the ground porous C / C preform with deionized water, and the number of cleaning times is 3-5 times, and the cleaning time for each time is 30-60 min; subsequently, boil the porous C / C preform at 100-350 °C for 1-6 h until no bubbles emerge on the surface of the porous C / C preform, and then dry the porous C / C preform at 60-100 °C for 6-12 h, obtaining the porous preform.

4. The preparation method of a transition metal carbonitride ceramic matrix modified C / C composite material according to claim 1, characterized in that Introduce a nitrogen source into the interior of the porous preform through the precursor infiltration pyrolysis process, including: Impregnation process: Vacuum impregnate the porous preform in the homogeneous polysilazane solution, and then dry the porous preform at 150-180 °C for 2-10 h; repeat the impregnation process 2-5 times, obtaining a first sample; Pyrolysis process: Subject the first sample to high-temperature pyrolysis to convert the organic precursor into an inorganic ceramic, obtaining a second sample; Repeat the impregnation process and the pyrolysis process for the second sample 1-3 times, obtaining the porous nitrogen-containing C / C preform.

5. The preparation method of a transition metal carbonitride ceramic matrix modified C / C composite material according to claim 1 or 4, characterized in that, The preparation process of the homogeneous polysilazane solution includes: Add the powder material to the polysilazane solution and mix evenly to obtain the homogeneous polysilazane solution; wherein, 0.01-2 g of the powder material is added corresponding to every 50-70 ml of the polysilazane solution.

6. The preparation method of a transition metal carbonitride ceramic matrix modified C / C composite material according to claim 5, characterized in that, The transition metal in the transition metal disilicide is at least one of Hf, Zr, Ta, Ni, and Ti.

7. The preparation method of a transition metal carbonitride ceramic matrix modified C / C composite according to claim 4, characterized in that, The pyrolysis process specifically includes: Introduce nitrogen into the equipment used in the pyrolysis process and perform a gas washing operation to remove the oxygen in the furnace; After the gas washing is completed, introduce nitrogen into the equipment used in the pyrolysis process, and then heat up to 280-350 °C at a rate of 2-10 °C / min and keep the temperature for 1-3 h to perform a curing reaction; After the curing reaction is completed, the temperature is then raised to 900 - 1400 °C at a rate of 2 - 10 °C / min and held for 1 - 3 h to convert the organic precursor into an inorganic ceramic. Then, the temperature is lowered to 300 °C at a rate of 2 - 10 °C / min, and then cooled to room temperature with the furnace to obtain a second sample.

8. The preparation method of a transition metal carbonitride ceramic matrix modified C / C composite material according to claim 1, characterized in that, The process of matrix modification of the porous nitrogen-containing C / C preform by infiltrating powder and reactive infiltration process includes a high-temperature treatment process. During the high-temperature treatment, the pressure is controlled at 5 Pa - 0.1 MPa, and it is heated from room temperature to 1700 - 2100 °C at a heating rate of 4 - 10 °C / min and held for 0.5 - 2 h. Then, it is cooled with the furnace to obtain the C / C composite modified with transition metal carbonitride ceramic matrix. Among them, the infiltrated powder is the same as the powder material used in the precursor impregnation pyrolysis process.

9. The preparation method of a transition metal carbonitride ceramic matrix modified C / C composite material according to claim 8, characterized in that, The process of matrix modification of the porous nitrogen-containing C / C preform by infiltrating powder and reactive infiltration process further includes: Preparation work: Clean the porous nitrogen-containing C / C preform. Lay 3 - 5 layers of graphite paper on the inner wall of the graphite crucible, lay 5 - 15 mm thick infiltrated powder at the bottom of the crucible, place the cleaned porous nitrogen-containing C / C preform parallel to the direction of the wire mesh layer on the infiltrated powder laid at the bottom of the crucible. Then, continue to add infiltrated powder to completely cover the porous nitrogen-containing C / C preform and be 5 - 15 mm higher than the upper surface of the porous nitrogen-containing C / C preform. Then, perform sealing treatment. Then place the graphite crucible in a graphite furnace for the high-temperature treatment process.

10. A transition metal carbonitride ceramic matrix modified C / C composite material, characterized in that, The C / C composite modified with transition metal carbonitride ceramic matrix is prepared by the preparation method according to any one of claims 1 - 9.

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