Preparation method of ultrahigh-temperature ceramic matrix modification and coating integrated carbon-based composite material

Abstract

The invention discloses a preparation method of an ultrahigh-temperature ceramic matrix modification and coating integrated carbon-based composite material, and belongs to the technical field of matrix modification and coating integrated carbon-based composite material preparation. Two functional materials are laid on the surface of low-density carbon / carbon (C / C) in a layered mode, infiltration powder on the inner layer is used for matrix modification, and coating powder on the outer layer is used for in-situ coating generation. And finally, applying pressure in a vacuum environment through an SPS process, so that the silicide alloy melt permeates into the C / C matrix under the assistance of the molten salt to generate carbide, and meanwhile, the outer-layer powder is converted into a compact ceramic coating in situ. The method is based on the SPS technology, and matrix modification and coating in-situ generation are synchronously achieved through a one-step method. According to the method, the thickness of the coating is controlled by regulating and controlling the quality of powder, and strong interface bonding of the coating and a modified matrix is achieved through melt permeation and interface mechanical occlusion.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of matrix-modified and coating-integrated carbon-based composites, and particularly relates to a method for preparing a matrix-modified and coating-integrated carbon-based composite of ultra-high temperature ceramics. Background Art

[0002] Carbon / carbon (C / C) composites have shown important application potential in high-temperature thermal structure components in the aerospace field due to their excellent high-temperature mechanical properties and thermal stability. However, C / C composites are prone to oxidation ablation in a high-temperature aerobic environment, resulting in a sharp degradation of material properties and limiting their further application. To address this problem, the existing technologies mainly adopt two strategies: matrix modification (enhancing the intrinsic ablation resistance of the matrix by introducing antioxidant components) and surface coating (isolating oxygen erosion by coating with a ceramic coating). However, both of these strategies have significant limitations - in matrix modification, it is difficult to completely block oxygen diffusion due to partial exposure of the matrix, and in coating technology, due to the difference in thermal expansion coefficients between the matrix and the coating, interface cracking or even spalling is likely to occur during thermal shock or ablation. To break through the bottleneck of single technologies, researchers have proposed a synergistic protection concept of matrix modification and coating integration to achieve overall thermal protection of the material.

[0003] CN112624801B reports a method for modifying C / C composites with (SiCNW) / (ZrC matrix-coating integration). By pre-preparing a SiC nanowire framework, a ZrC(SiC) coating can be formed on the material surface while preparing a ZrC-modified matrix by precursor infiltration and pyrolysis. This method can integrally form a ZrC(SiC) ceramic coating and a doped matrix, which can not only effectively block the erosion of the oxygen atmosphere and high-speed particles on the matrix, but also reduce the oxidation activity of the matrix, and at the same time alleviate the problem of mismatch in thermal expansion coefficients between the matrix and the coating, improving the ablation resistance of C / C composites from the inside out. However, this method requires multiple high-temperature heat treatments, resulting in a long preparation cycle and difficult to precisely control the coating thickness.

[0004] In Reference 1 "Liu C X, Su Z A, Huang Q Z, Chen J X, Yang X, Cao L X, Yin T, Zhong P, Ablation behavior of ZrC-SiC coated C / C-ZrC-SiC composites prepared by precursor infiltration pyrolysis combined with reactive melt infiltration, Journal of Alloys and Compounds, 597 (2014) 236-242", C / C-ZrC-SiC composites with ZrC-SiC coatings were prepared by precursor infiltration pyrolysis combined with reactive melt infiltration, showing relatively excellent ablation resistance. However, the precursor infiltration pyrolysis process was repeated 9 times in this method, and reactive melt infiltration was also combined, resulting in a complex preparation process and a long preparation cycle.

[0005] In Reference 2 "Xie J, Jia Y J, Zhao Z G, Li K Z, Sun G D, Li H, Su X H, A ZrC-SiC / SiC multilayer anti-ablation coating for ZrC modified C / C composites, Vacuum, 157 (2018) 324-331", C / C-ZrC composites with ZrC-SiC outer coatings and SiC inner coatings were prepared by precursor infiltration pyrolysis combined with supersonic atmospheric plasma spraying. Although strong interfacial bonding was achieved, the preparation cost of this method was high and the preparation process was cumbersome. Summary of the Invention

[0006] The object of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide a preparation method for a carbon-based composite material integrating ultra-high temperature ceramic matrix modification and coating, so as to solve the problems of cumbersome preparation processes and long process cycles for composite materials for matrix modification and coating preparation in the prior art.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A preparation method for a carbon-based composite material integrating ultra-high temperature ceramic matrix modification and coating, comprising the following steps: S1, laying coating powder in an SPS mold, laying infiltration powder on the coating powder, placing a low-density C / C composite material on the infiltration powder, laying infiltration powder on the upper surface of the C / C composite material, and laying coating powder on the upper surface of the infiltration powder; The infiltration powder is a mixed powder of silicide alloy powder, molten salt and catalyst; the coating powder is a mixed powder of silicide alloy powder, carbon powder, Al2O3 and catalyst powder; S2, subject the mold to pressure increase and heat treatment by SPS, and an integrated carbon-based composite material is obtained after cooling.

[0008] A further improvement of the present invention lies in: Preferably, in S1, the density of the low-density C / C composite material is 1.1~1.4 g / cm 3 ..

[0009] Preferably, in S1, the silicide alloy powder is one or more of HfSi2, ZrSi2, TiSi2, TaSi2, NbSi2 powders.

[0010] Preferably, in S1, the molten salt is one or more of CaCl2, NaCl, KCl powders.

[0011] Preferably, in S1, the catalyst is iron element or its compound, nickel element or its compound.

[0012] Preferably, in S1, during the preparation process of the infiltration powder, after mixing the silicide alloy powder and the molten salt by a ball mill, a catalyst is added to the mixed powder, and the infiltration powder is obtained after grinding.

[0013] Preferably, in S1, the preparation process of the coating powder is to mix the silicide alloy powder, carbon powder and Al2O3 by a ball mill, add a catalyst to the mixed powder, and the coating powder is obtained after grinding.

[0014] Preferably, in S1, in the infiltration powder, the mixing mass ratio of the silicide alloy powder and the molten salt is 6:1~10:1.

[0015] Preferably, in S1, in the coating powder, the mixing molar ratio of the silicide alloy powder, carbon powder and Al2O3 powder is 30:10:1~40:20:1.

[0016] Preferably, in S2, during the pressure increase and heat treatment process, the pressure is 6~10 kN; the heat treatment temperature is 1500~2100 °C, and the heat preservation time is 30~120 min.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a rapid preparation method for an integrated carbon-based composite material with ultra-high temperature ceramic matrix modification and coating; in the present invention, two functional materials are laid layer by layer on the surface of low-density carbon / carbon (C / C), wherein the infiltrated powder in the inner layer is used for matrix modification, and the coating powder in the outer layer is used for in-situ coating generation. Finally, under a vacuum environment, pressure is applied through the SPS process, enabling the silicide alloy melt to infiltrate into the C / C matrix with the assistance of molten salt to generate carbides, and simultaneously the outer layer powder is in-situ transformed into a dense ceramic coating; based on the SPS technology, matrix modification and in-situ coating generation are synchronously achieved through a one-step method. Since the main materials of the coating in the method of the present invention (carbon powder + silicon alloy powder) and the matrix and modification materials are of the same type, all including carbon and silicon alloy, during the same heating temperature, the infiltration process of the composite material and the reaction of the coating material itself can proceed simultaneously. As the infiltrated powder in the inner layer infiltrates, the materials in the coating powder can react with each other. By the later stage of the coating reaction, the coating itself can partially react with the C / C matrix material to form a good bonding force. This method controls the coating thickness by regulating the powder quality, and realizes a strong interfacial bond between the coating and the modified matrix through molten infiltration and interfacial mechanical interlocking (after continuous ablation with an oxyacetylene flame of 4.2 MW / M 2 for 500 s, there is no obvious peeling of the coating). Compared with the traditional step-by-step process, this method gives full play to the advantages of the SPS equipment, shortens the preparation cycle to 1 - 2 hours, synchronously realizes matrix modification and in-situ coating generation through a one-step method, has simple operation steps, omits multiple rounds of complex processes, significantly improves the process efficiency, and reduces the preparation cost; this method realizes a strong interfacial bond between the coating and the modified matrix through molten infiltration and interfacial mechanical interlocking, is applicable to the efficient integrated preparation of ceramic-modified C / C and ceramic coatings, and has significant engineering application value. The method of the present invention has the following advantages: 1. This method only needs one step to complete the preparation of the integrated carbon-based composite material with ultra-high temperature ceramic matrix modification and coating. Matrix modification is carried out through the infiltration of the powder close to the matrix side, in-situ coating preparation is carried out through the powder far from the matrix side, and strong interfacial toughness bonding is achieved through pressure and the infiltration process.

[0018] 2. Molten salt is set in the infiltrated powder in the inner layer, which can accelerate the infiltration of the silicon alloy modification powder and prevent the silicon alloy from sintering before infiltrating into the composite material. On the other hand, adding Al2O3 powder to the coating powder in the outer layer can be used as the raw material for the outer coating reaction and can also be used as a sintering aid to promote the sintering of the surface coating.

[0019] 3. Since the SPS mold has a small size, it ensures the stacking fixity of the powder and is not easy to move. Therefore, the coating thickness is controlled by regulating the powder quality, and the controllability of the coating composition and thickness is relatively strong.

[0020] 4. The high-throughput process characteristics of this method support the rapid screening and optimization of coating components and modification elements, accelerating the material R & D cycle. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the stacking order of raw materials in the SPS mold before final heat treatment; Figure 2 It is the macroscopic and microscopic structures of the sample prepared in Example 1: (a) Macroscopic photos before and after continuous ablation of oxyacetylene flame with 4.2 MW / M 2 for 500 s; (b) XRD spectrum of the sample surface; (c)-(i) SEM photos of the sample cross-section; Figure 3 It is the macroscopic and microscopic structures of the sample prepared in Example 2: (a) Macroscopic photo of the sample; (b) XRD spectrum of the sample surface; (c) and (d) are SEM photos of the sample cross-section; Figure 4 It is the macroscopic and microscopic structures of the sample prepared in Example 3: (a) Macroscopic photo of the sample; (b) XRD spectrum of the sample surface; (c) and (d) are SEM photos of the sample cross-section. Detailed Description of the Invention

[0022] The present invention will be further described in detail below with reference to the drawings: To enable those skilled in the art to understand the features and effects of the present invention, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art for the present invention. In case of conflict, the definition in this specification shall prevail.

[0023] In this article, unless otherwise specified, "comprising", "including", "containing", "having" or similar terms cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A only comprises a".

[0024] The present invention will be further described below with specific examples. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it 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 also fall within the scope defined by the appended claims of this application.

[0025] Conventional instruments and equipment in the art are used in the following examples. For the experimental methods without specific conditions noted in the following examples, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following examples. Unless otherwise specified, commercially available products with conventional specifications in the art are used. In the specification of the present invention and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0026] As the problems raised in the background art, the traditional manufacturing process of integrating matrix modification and coating usually proceeds in two steps: ceramic matrix modification and the formation of ceramic coatings. Therefore, the cumbersome preparation process and the interfacial bonding between the coating and the matrix are the most concerned issues. A rapid preparation method of a carbon-based composite material integrating ultra-high temperature ceramic matrix modification and coating proposed by the present invention is based on SPS technology and synchronously realizes matrix modification and in-situ coating generation through a one-step method. Its core process includes: ball-milling and mixing silicide alloys with molten salt systems and carbon powder-Al2O3 composite systems respectively to form inner matrix modification powder materials and outer coating preparation powder materials. Mix the two powder materials with iron / nickel-based catalysts in proportion, and sequentially lay the inner modification powder material and the outer coating powder material on the surface of low-density C / C. On the one hand, it promotes the sintering of the coating, and on the other hand, it catalyzes the in-situ generation of nano-toughening phases to optimize the material properties. Construct a functional layered structure. Place the installed mold in an SPS furnace and perform high-temperature heat treatment by setting appropriate temperature and pressure programs. With the assistance of the flow action of the molten salt at high temperature for infiltration, the silicide alloy melt reacts with the pyrolytic carbon in the C / C matrix at a low-viscosity environment to form carbides for matrix modification. At the same time, the outer silicide alloy reacts in-situ with carbon powder or Al2O3 to form a dense carbide / oxide / silicide ceramic coating. Finally, clean the residual graphite paper on the surface to obtain a matrix-coating integrated composite material with a tightly bonded interface, and the coating thickness is precisely controlled by the powder addition amount.

[0027] The present invention discloses a preparation method of a carbon-based composite material integrating ultra-high temperature ceramic matrix modification and coating, comprising the following steps: Step 1, ultrasonically clean the low-density C / C composite material with deionized water and dry it in a far-infrared drying oven for 15-20 h; Step 2, put the silicide alloy powder and molten salt in a ball mill according to a certain ratio for ball-milling and mixing to obtain powder A; Step 3, put the silicide alloy powder, carbon powder, and Al2O3 in a ball mill according to a certain ratio for ball-milling and mixing to obtain powder B; Step 4, mix powder A with the catalyst in a mortar according to a certain ratio and mix evenly to obtain powder C, which is the infiltration powder; mix powder B with the catalyst in a mortar according to a certain ratio and mix evenly to obtain powder D, which is the coating powder; Step 5, evenly laying a certain mass of powder C on the upper and lower parts of the low-density C / C obtained in step 1; Step 6, evenly lay a certain mass of powder D outside the powder laid in step 5 and place it in the SPS mold, so that the raw materials in the mold are from top to bottom: powder D-powder C-low density C / C-powder C-powder D; Step 7, placing the assembled mold in an SPS furnace, setting the pressure and temperature program for high temperature heat treatment, and taking it out after cooling; Step 8, use sandpaper to polish and clean the upper and lower surfaces of the sample and the residual graphite paper around it, so as to obtain a carbon-based composite material with integrated ultra-high temperature ceramic matrix modification and coating.

[0028] In some embodiments of the present invention, the low-density C / C density of step 1 is 1.1-1.4 g / cm 3 .

[0029] In some embodiments of the present invention, the silicide alloy powder in steps 2 and 3 can be one or more of HfSi2, ZrSi2, TiSi2, TaSi2, and NbSi2 powder.

[0030] The molten salt in step 2 includes one or more of CaCl2, NaCl, and KCl powders. The addition of molten salt can reduce the melting point of the infiltrated powder as a whole, enhance the fluidity of the infiltrated powder, and prevent the silicide alloy powder from sintering and agglomerating before infiltration into the interior.

[0031] In some embodiments of the present invention, the catalyst in step 4 includes iron or its compound, nickel or its compound, such as ferrous sulfate or nickel nitrate hexahydrate; the catalyst is suitable for both infiltration powder and coating powder.

[0032] In some embodiments of the present invention, the mass ratio of the silicide alloy powder to the molten salt in step 2 is 6: 1 to 10: 1.

[0033] In some embodiments of the present invention, the molar ratio of the silicide alloy powder, carbon powder and Al2O3 in step 3 is 30:10:1~40:20:1. By controlling the molar ratio of the silicide alloy powder, carbon powder and Al2O3, the proportion of the product, such as the content of silicide, oxide and carbide, can be controlled.

[0034] In some embodiments of the present invention, the mass ratio of the process powder to the catalyst in step 4 is 200:1 to 500:1.

[0035] In some embodiments of the present invention, the pressure program described in step 7 is to apply a pressure of 6-10 kN throughout the process, and the penetration speed can be controlled by controlling the process pressure.

[0036] In some embodiments of the present invention, the heating and cooling process in step 7 is carried out in a vacuum environment. The heating rate below 1500°C is 400 - 500°C / min, and the heating rate above 1500°C is 100 - 200°C / min. It is heated to 1500 - 2100°C, and the holding time is 30 - 120 min. In the present invention, through the setting of this heating temperature, the reaction generation of the coating and the infiltration of the infiltration material can be carried out simultaneously. At the same time, the trapezoidal temperature heating method is adopted to give the infiltration powder enough flowing and infiltration time.

[0037] Exemplarily, the heating temperature in the early stage of the above-mentioned heating can be 400°C / min, 450°C / min, and 500°C / min, the heating temperature in the later stage can be 100°C / min, 150°C / min, and 200°C / min, and the heating temperature can be 1500°C, 1600°C, 1700°C, 1800°C, 1900°C, 2000°C, and 2100°C. The holding time can be 30 min, 50 min, 80 min, 100 min, and 120 min.

[0038] An ultra-high temperature ceramic matrix modified and coating integrated carbon-based composite material prepared by the method according to any one of the above.

[0039] The following is further illustrated with specific examples.

[0040] Example 1 Step 1: Use deionized water to ultrasonically clean the low-density C / C with a size of Φ29mm×10mm and a density of 1.28 g / cm 3 and place it in a 100°C far-infrared drying oven for drying for 20 h.

[0041] Step 2: Pour the mixed powder of HfSi2 and ZrSi2 with a molar ratio of 1:1 and CaCl2 and NaCl with a mass ratio of 8:1 into a ball mill tank and use a ball mill for ball milling. The ball-to-powder ratio is 2:1, the ball milling speed is 420 r / min. After ball milling for 7 h, place the powder in a 100°C far-infrared drying oven for drying for 12 h to obtain powder A1.

[0042] Step 3: Mix HfSi2 and ZrSi2 with a molar ratio of 1:1 and mix them with carbon powder and Al2O3 with a molar ratio of 36:17:1 and pour them into a ball mill tank and use a ball mill for ball milling. The ball-to-powder ratio is 2:1, the ball milling speed is 420 r / min. After ball milling for 7 h, place the powder in a 100°C far-infrared drying oven for drying for 12 h to obtain powder B1.

[0043] Step 4: Mix powder A1 and powder B1 with nickel powder in a mortar at a mass ratio of 300:1 respectively to obtain powder C1 and powder D1 evenly.

[0044] Step 5: Evenly lay 7.35 g of powder C1 on the upper and lower sides of low-density C / C respectively.

[0045] Step 6: Continue to evenly lay 3.99 g of powder D1 outside the powder laid in Step 5, place it above the lower punch of the SPS mold, wrap the low-density C / C and the powder with graphite paper around, place graphite paper with a size of Φ30 mm in the area where the powder contacts the upper and lower punches, and finally press in the upper punch.

[0046] Step 7: Before the final heat treatment, the raw materials in the mold from top to bottom are: powder D1 - powder C1 - low-density C / C - powder C1 - powder D1. Place the installed mold in the SPS furnace, set the pressure to 7 kN, heat it to 1500 °C at a heating rate of 450 °C / min in a vacuum environment, continue to heat it to 1800 °C at a heating rate of 200 °C / min, hold for 60 min, and cool it to room temperature at a cooling rate of 200 °C / min and then take it out.

[0047] Step 8: Use sandpaper to polish and clean the residual graphite paper on the upper and lower surfaces and around the sample to obtain a (Zr, Hf)C-SiC modified C / C composite material with a ZrC-HfC-ZrO2-HfO2-SiO2 composite coating.

[0048] See Figure 2 , after the sample is continuously ablated by an oxyacetylene flame with a power of 4.2 MW / m 2 for 500 s, there is no obvious peeling of the coating ((a) figure), which proves that the coating has excellent bonding strength. The surface XRD of the sample is shown in (b) figure, and it can be seen that the coating contains ZrC, HfC, ZrO2, HfO2 and SiO2. The cross-sectional SEM is shown in (c) figure - (i) figure. From (c) - (e) figures, it can be seen that a continuous and dense coating is formed on the surface of the matrix, the coating thickness is ~175 µm, and there is mechanical interlocking between the coating and the matrix, and they are closely combined. (f) figure is the SEM photo of the inside of the matrix, and it can be seen that the ceramic content inside the matrix is high and the structure is dense. (g) figure - (i) figures are the SEM photos from the surface of the coating to the interface between the coating and the matrix, and it can be seen that the grains of the coating are fine.

[0049] Example 2 Step 1: Use deionized water to ultrasonically clean low-density C / C with a size of Φ29 mm × 10 mm and a density of 1.34 g / cm 3 and place it in a 100 °C far-infrared drying oven to dry for 15 - 20 h.

[0050] Step 2: Pour HfSi2 and ZrSi2 in a molar ratio of 1:1 and a mixed powder of CaCl2 and NaCl in a mass ratio of 9:1 into a ball mill jar, and perform ball milling using a ball mill. The ball-to-material ratio is 2:1, the ball milling speed is 420 r / min. After ball milling for 7 h, place the powder in a far-infrared drying oven at 100 °C and dry for 12 h to obtain powder A2.

[0051] Step 3: Mix HfSi2 and ZrSi2 in a molar ratio of 1:1, and pour them into a ball mill jar together with carbon powder and Al2O3 in a molar ratio of 40:15:1, and perform ball milling using a ball mill. The ball-to-material ratio is 2:1, the ball milling speed is 420 r / min. After ball milling for 7 h, place the powder in a far-infrared drying oven at 100 °C and dry for 12 h to obtain powder B2.

[0052] Step 4: Mix powder A2 and powder B2 with nickel powder in a mass ratio of 400:1 respectively in a mortar to obtain powder C2 and powder D2.

[0053] Step 5: Uniformly lay 6.42 g of powder C2 on the upper and lower surfaces of low-density C / C respectively.

[0054] Step 6: Continue to uniformly lay 1.00 g of powder D2 outside the powder laid in Step 5, place it above the lower punch of the SPS mold, wrap the low-density C / C and the powder with graphite paper, place graphite paper with a size of Φ30 mm in the area where the powder contacts the upper and lower punches, and finally press in the upper punch.

[0055] Step 7: Before the final heat treatment, the raw materials in the mold from top to bottom are: powder D2 - powder C2 - low-density C / C - powder C2 - powder D2. Place the installed mold in an SPS furnace, set the pressure to 8 kN, heat it to 1500 °C at a heating rate of 450 °C / min in a vacuum environment, continue to heat it to 1650 °C at a heating rate of 200 °C / min, hold for 30 min, and cool it to room temperature at a cooling rate of 200 °C / min and then take it out.

[0056] Step 8: Use sandpaper to polish and clean the residual graphite paper on the upper and lower surfaces and around the sample, and then obtain the (Zr, Hf)C-SiC modified C / C composite material with a ZrC-HfC-ZrO2-HfO2-ZrSi2-HfSi2 composite coating.

[0057] Its macroscopic photograph is as shown in Figure 3 Figure (a) in, and it can be seen that the coating uniformly covers the surface of the composite material. Its surface XRD is as shown in Figure 3As shown in Figure (a), it can be seen that the coating contains ZrC, HfC, ZrO2, HfO2, ZrSi2 and HfSi2. The cross-sectional SEM is shown in Figures (c) and (d). As can be seen from Figure 3 Figure (a) in, a continuous and dense coating is formed on the surface of the material. The coating thickness is ~40 µm, and the interface bonding with the substrate is good. Figure (d) is the SEM photo of the inside of the substrate, from which it can be seen that the ceramic content inside the substrate is high and the structure is dense.

[0058] Example 3 Step 1: Ultrasonically clean the low-density C / C with a size of Φ29mm×10mm and a density of 1.32 g / cm 3 using deionized water, and place it in a 100°C far-infrared drying oven for drying for 15 - 20 h.

[0059] Step 2: Pour HfSi2 and ZrSi2 with a molar ratio of 1:1 and a mixed powder of CaCl2 and NaCl with a mass ratio of 7:1 into a ball mill tank and ball mill using a ball mill. The ball-to-powder ratio is 2:1, the ball mill rotation speed is 420 r / min. After ball milling for 7 h, place the powder in a 100°C far-infrared drying oven for drying for 12 h to obtain powder A3.

[0060] Step 3: Mix HfSi2 and ZrSi2 with a molar ratio of 1:1, carbon powder and Al2O3 with a molar ratio of 40:20:1, pour them into a ball mill tank and ball mill using a ball mill. The ball-to-powder ratio is 2:1, the ball mill rotation speed is 420 r / min. After ball milling for 7 h, place the powder in a 100°C far-infrared drying oven for drying for 12 h to obtain powder B3.

[0061] Step 4: Mix powder A3 and powder B3 with ferrous sulfate respectively in a mortar with a mass ratio of 500:1 to obtain powder C3 and powder D3.

[0062] Step 5: Uniformly lay 7.55 g of powder C3 on the upper and lower sides of the low-density C / C.

[0063] Step 6: Continuously and uniformly lay 2.10 g of powder D3 outside the powder laid in Step 5, place it above the lower punch of the SPS mold, wrap the low-density C / C and the powder with graphite paper, place graphite paper with a size of Φ30mm in the area where the powder contacts the upper and lower punches, and finally press in the upper punch.

[0064] Step 7: Before the final heat treatment, the raw materials in the mold from top to bottom are: powder D3 - powder C3 - low-density C / C - powder C3 - powder D3. Place the installed mold in the SPS furnace, set the pressure to 8 kN, heat it to 1500 °C at a heating rate of 450 °C / min in a vacuum environment, continue to heat it to 1900 °C at a heating rate of 200 °C / min, hold for 30 min, and then cool it to room temperature at a cooling rate of 200 °C / min and take it out.

[0065] Step 8: Use sandpaper to polish and clean the residual graphite paper on the upper and lower surfaces and around the sample, and then the (Zr, Hf)C-SiC modified C / C composite material with a ZrC-HfC-ZrO2-HfO2 composite coating is obtained.

[0066] See Figure 4 , the macroscopic photograph is shown in Figure (a). It can be seen that the coating uniformly covers the surface of the composite material without obvious macroscopic defects. Its surface XRD is shown in Figure (b). It can be seen that the coating has a high content of ZrC, HfC and weak ZrO2, HfO2. Its cross-sectional SEM is shown in Figures (c) and (d). It can be seen from Figure (c) that a continuous and dense coating is formed on the surface of the material. The coating thickness is ~80 µm, there is mechanical interlocking with the matrix, and the interface is tightly bonded. Figure (d) is the SEM photograph of the interior of the matrix. It can be seen that the ceramic content in the matrix is high and the structure is dense.

[0067] Example 4 Step 1: Use deionized water to ultrasonically clean the low-density C / C with a size of Φ29 mm × 10 mm and a density of 1.28 g / cm 3 and place it in a 100 °C far-infrared drying oven to dry for 20 h.

[0068] Step 2: Pour TaSi2 and TiSi2 in a molar ratio of 1:1 and the mixed powder of CaCl2 and KCl in a mass ratio of 6:1 into the ball mill tank and use a ball mill for ball milling. The ball-to-powder ratio is 2:1, the ball milling speed is 420 r / min. After ball milling for 7 h, place the powder in a 100 °C far-infrared drying oven to dry for 12 h to obtain powder A4.

[0069] Step 3: Mix TaSi2 and TiSi2 in a molar ratio of 1:1 and mix them with carbon powder and Al2O3 in a molar ratio of 30:10:1, pour them into the ball mill tank and use a ball mill for ball milling. The ball-to-powder ratio is 2:1, the ball milling speed is 420 r / min. After ball milling for 7 h, place the powder in a 100 °C far-infrared drying oven to dry for 12 h to obtain powder B4.

[0070] Step 4: Mix powder A4 and powder B4 with nickel powder respectively in a mortar at a mass ratio of 300:1 to obtain powder C4 and powder D4.

[0071] Step 5: Uniformly lay 7.35 g of powder C4 on the upper and lower sides of the low-density C / C.

[0072] Step 6: Continuously and uniformly lay 3.99 g of powder D4 outside the powder laid in Step 5, place it above the lower punch of the SPS mold, wrap the low-density C / C and the powder with graphite paper, place graphite paper with a size of Φ30 mm in the area where the powder contacts the upper and lower punches, and finally press in the upper punch.

[0073] Step 7: Before the final heat treatment, the raw materials in the mold from top to bottom are: powder D4 - powder C4 - low-density C / C - powder C4 - powder D4. Place the installed mold in the SPS furnace, set the pressure to 7 kN, heat it to 1500 °C at a heating rate of 450 °C / min in a vacuum environment, continue to heat it to 1650 °C at a heating rate of 200 °C / min, hold for 120 min, and cool it to room temperature at a cooling rate of 200 °C / min and then take it out.

[0074] Step 8: Use sandpaper to polish and clean the residual graphite paper on the upper and lower surfaces and around the sample to obtain a (Ta, Ti)C-SiC modified C / C composite material with a TaC-TiC-Ta2O5-TiO2-SiO2 composite coating.

[0075] Example 5 Step 1: Ultrasonically clean low-density C / C with a size of Φ29 mm × 10 mm and a density of 1.28 g / cm 3 using deionized water and dry it in a 100 °C far-infrared drying oven for 15 h.

[0076] Step 2: Pour TaSi2 and NbSi2 in a molar ratio of 1:1 and a mixed powder of CaCl2 and NaCl in a mass ratio of 10:1 into a ball milling tank and use a ball mill for ball milling. The ball-to-powder ratio is 2:1, the ball milling speed is 420 r / min. After ball milling for 7 h, place the powder in a 100 °C far-infrared drying oven and dry it for 12 h to obtain powder A5.

[0077] Step 3: Mix TaSi2 and NbSi2 in a molar ratio of 1:1 and mix them with carbon powder and Al2O3 in a molar ratio of 35:20:1, pour them into a ball milling tank and use a ball mill for ball milling. The ball-to-powder ratio is 2:1, the ball milling speed is 420 r / min. After ball milling for 7 h, place the powder in a 100 °C far-infrared drying oven and dry it for 12 h to obtain powder B5.

[0078] Step 4: Mix powder A5 and powder B5 with nickel powder in a mortar at a mass ratio of 300:1 respectively to obtain powder C5 and powder D5.

[0079] Step 5: Uniformly lay 7.35 g of powder C5 on the upper and lower surfaces of low-density C / C.

[0080] Step 6: Continuously and uniformly lay 3.99 g of powder D5 outside the powder laid in Step 5, place it above the lower punch of the SPS mold, wrap the low-density C / C and the powder with graphite paper, place graphite paper with a size of Φ30 mm in the area where the powder contacts the upper and lower punches, and finally press in the upper punch.

[0081] Step 7: Before the final heat treatment, the raw materials in the mold from top to bottom are: powder D5 - powder C5 - low-density C / C - powder C5 - powder D5. Place the installed mold in the SPS furnace, set the pressure to 7 kN, heat it to 1500 °C at a heating rate of 450 °C / min in a vacuum environment, continue to heat it to 2100 °C at a heating rate of 200 °C / min, hold for 30 min, and cool it to room temperature at a cooling rate of 200 °C / min and then take it out.

[0082] Step 8: Use sandpaper to polish and clean the residual graphite paper on the upper and lower surfaces and the periphery of the sample, and then the (Ta, Nb)C-SiC modified C / C composite material with a TaC-NbC-Ta2O5-NbO2-SiO2 composite coating can be obtained.

[0083] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an ultra-high temperature ceramic matrix modified and coated integrated carbon-based composite material, characterized in that: The following steps are involved: S1, laying coating powder in the SPS mold, laying infiltration powder on the coating powder, placing low-density C / C composite material on the infiltration powder, laying infiltration powder on the upper surface of the C / C composite material, and laying coating powder on the upper surface of the infiltration powder; The infiltration powder is a mixed powder of silicide alloy powder, molten salt and catalyst; the coating powder is a mixed powder of silicide alloy powder, carbon powder, Al2O3 and catalyst powder; S2, the mold is subjected to pressurized and heated heat treatment by SPS, and an integrated carbon-based composite material is obtained after cooling.

2. The method for preparing a carbon-based composite material integrating ultra-high temperature ceramic matrix modification and coating according to claim 1, characterized in that: In S1, the density of the low-density C / C composite material is 1.1-1.4 g / cm 3 .

3. The method for preparing an ultra-high temperature ceramic matrix modified and coated integrated carbon-based composite material according to claim 1, characterized in that: In S1, the silicide alloy powder is one or more of HfSi2, ZrSi2, TiSi2, TaSi2, and NbSi2 powder.

4. The method for preparing an ultra-high temperature ceramic matrix modified and coated integrated carbon-based composite material according to claim 1, characterized in that: In S1, the molten salt is one or more of CaCl2, NaCl, and KCl powder.

5. The method for preparing an ultra-high temperature ceramic matrix modified and coated integrated carbon-based composite material according to claim 1, characterized in that: In S1, the catalyst is iron or its compound, nickel or its compound.

6. The method for preparing an ultra-high temperature ceramic matrix modified and coated integrated carbon-based composite material according to claim 1, characterized in that: In S1, during the preparation of the infiltration powder, the silicide alloy powder and the molten salt are mixed by a ball mill, a catalyst is added to the mixed powder, and the infiltration powder is obtained after grinding.

7. The method for preparing an ultra-high temperature ceramic matrix modified and coated integrated carbon-based composite material according to claim 1, characterized in that: In S1, the coating powder is prepared by mixing silicide alloy powder, carbon powder and Al2O3 in a ball mill, adding a catalyst to the mixed powder, and grinding to obtain the coating powder.

8. The method for preparing an ultra-high temperature ceramic matrix modified and coated integrated carbon-based composite material according to claim 1, characterized in that: In S1, in the infiltration powder, the mixing mass ratio of the silicide alloy powder and the molten salt is 6: 1~10:

1.

9. The method for preparing an ultra-high temperature ceramic matrix modified and coated integrated carbon-based composite material according to claim 1, characterized in that: In S1, in the coating powder, the mixing molar ratio of the silicide alloy powder, the carbon powder and the Al2O3 powder is 30:10:1~40:20:

1.

10. The method for preparing an ultra-high temperature ceramic matrix modified and coated integrated carbon-based composite material according to claim 1, characterized in that: In S2, during the pressurized temperature treatment process, the pressure is 6~10kN; the heat treatment temperature is 1500~2100℃, and the insulation time is 30~120min.

Images