A multi-element ultra-high-temperature nanocomposite ceramic matrix composite material and a preparation method thereof

Abstract

The application discloses a kind of multi-element ultra-high temperature nanocomposite ceramic matrix composites and preparation method thereof, the multi-element ultra-high temperature nanocomposite ceramic matrix composites are composed of multi-element ultra-high temperature nanocomposite ceramic and porous fiber body, wherein multi-element ultra-high temperature nanocomposite ceramic is composed of oxygen-free silicon-based ceramic and multi-element transition metal carbonitride uniformly distributed therein, and the preparation method is: at least two metal element complexes are reacted with silicon-based polymer to obtain single-source precursor polymer;Then porous fiber body is placed in single-source precursor polymer solution for multiple times of impregnation pyrolysis, and the composite material provided by the application has a nanocomposite structure, an ultra-high temperature ceramic multi-element single-phase solid solution, the type, content and ratio of metal elements can be adjusted, the ultra-high temperature ceramic in the matrix is uniformly distributed and has a nanoscale grain size, and the method can avoid damage to the fiber during preparation, thereby achieving simultaneous improvement of the mechanical properties and oxidation ablation resistance of the composite material.

Description

Technical Field

[0001] This invention belongs to the field of ceramic matrix composite material preparation, specifically relating to a multi-component ultra-high temperature nano-multiphase ceramic matrix composite material and its preparation method. Background Technology

[0002] With the advent of the 21st-century era of high-speed space exploration, human development of near-space is increasing, particularly in areas such as hypersonic vehicles, where competition is intensifying. During hypersonic flight, critical components such as the nose cone and wing leading edge must withstand temperatures exceeding 2000°C due to aerodynamic heating, resulting in intense thermal shock and plasma ablation. Therefore, C / SiC and SiC / SiC ceramic matrix composites are no longer sufficient. Ultra-high temperature ceramics (UHTCs, such as HfC, ZrC, HfB2, and ZrB2) have been introduced into carbon fiber preforms to create C / UHTCs UHTCs UHTCs matrix composites in recent years due to their outstanding advantages, including high melting point (>3000°C), high modulus, high hardness, and high thermal stability, potentially filling this application gap. However, the oxidation and ablation resistance of UHTCs still needs improvement, especially at medium and low temperatures (800-1800°C), where their poor oxidation resistance severely limits their application range and reliability.

[0003] To improve the oxidation and ablation resistance of ultra-high temperature ceramic matrix composites, the most common strategies are diversification and multi-phase addition. Diversification involves adding a second phase (such as SiC, MoSi2, and LaB6) to the ultra-high temperature ceramic to form a dense oxide layer, thus creating a diversified ceramic. Multi-phase addition involves adding one or more transition metal components to a binary ultra-high temperature ceramic to create a single-phase, multi-component ultra-high temperature ceramic solid solution (such as Ta). 0.8 Hf 0.2 C, (Zr) 0.2 Ti 0.2 Hf 0.2 Nb 0.2 Ta)C,(Zr 0.25 Ti 0.25 Hf 0.25 Ta 0.25 In recent years, in order to further improve the oxidation and ablation resistance of ultra-high temperature ceramic matrix composites, researchers have begun to try to simultaneously diversify and multiphase, and have successfully prepared C / (Zr... 0.2 Ti 0.2 Hf 0.2 Nb 0.2 Multi-component ultra-high temperature ceramic matrix composites such as TaC-SiC have been developed, and their oxidation and ablation resistance has been improved. However, multi-component ultra-high temperature nano-composite ceramic matrix composites with greater performance advantages and application potential have not yet been reported.

[0004] Currently, the main methods for preparing ultra-high temperature ceramic matrix composites include chemical vapor infiltration (CVI), polymer impregnation pyrolysis (PIP), reactive melt infiltration (RMI), slurry impregnation (SI), and combinations of the above methods. However, there are still some shortcomings in the preparation of multi-component ultra-high temperature ceramic matrix composites using the above methods: (1) SI, CVI and RMI processes have limited ability to design and control the multi-component ultra-high temperature ceramic phase in the composite matrix, and it is difficult to accurately control the type and atomic ratio of metal elements in the multi-component ultra-high temperature ceramic; (2) SI, CVI and RMI processes cannot flexibly control the actual ratio of ultra-high temperature ceramic phase and added phase in the ceramic matrix, which limits the potential for further design and development of composite materials (e.g., controlling the content of multi-component ultra-high temperature ceramic in the matrix according to actual needs, preparing gradient ceramic matrix composites with gradually changing ultra-high temperature ceramic content, etc.); (3) SI, CVI and RMI processes cannot prepare ultra-high temperature ceramic matrix composites with nanocomposite structures. Even if nano-ceramic particles are introduced by physical methods, they will be difficult to achieve uniform distribution due to particle agglomeration, resulting in non-uniform material structure and performance, and failing to guarantee its reliability in extreme environments; (4) RMI method has been proven to be a very efficient method for preparing multi-component ultra-high temperature ceramic matrix composites in recent years, but because the high temperature melt is very easy to react with fibers and interface layers, the mechanical properties of the composite material will drop significantly. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the first objective of this invention is to provide a multi-element ultra-high temperature nano-composite ceramic matrix composite material.

[0006] The second objective of this invention is to provide a method for preparing multi-component ultra-high temperature nano-composite ceramic matrix composite materials.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention discloses a multi-component ultra-high temperature nanocomposite ceramic matrix composite material, which is prepared by polymer impregnation and pyrolysis of a single-source precursor polymer and porous fibers. The single-source precursor polymer is obtained by reacting a silicon-based polymer with transition metal small molecules, and after high-temperature pyrolysis, it transforms into a multi-component ultra-high temperature nanocomposite ceramic composed of multi-component transition metal carbonitrides and oxygen-free silicon-based ceramics.

[0009] This invention discloses a multi-component ultra-high temperature nano-composite ceramic matrix composite material. In this composite material, the multi-component ultra-high temperature nano-composite ceramic matrix is ​​composed of a uniformly distributed multi-component transition metal carbonitride phase and an oxygen-free silicon-based ceramic phase. The general chemical formula of the multi-component transition metal carbonitride is (Ti...).a Zr b Hf c Nb d Ta e Mo f W g C x N 1-x , 0<x<1, a+b+c+d+e+f+g=1, and at least two of a,b,c,d,e,f,g are not simultaneously 0, and the oxygen-free silicon-based ceramic is at least one of SiCN, SiBCN, Si3N4 and SiC.

[0010] The multi-component ultra-high temperature nano-composite ceramic matrix composite material provided by this invention has a matrix in which a uniformly distributed multi-component transition metal carbonitride phase forms a complex multi-component oxide (e.g., Ta) after ablation. x Nb 1-x )2(Zr y Hf 1-y )6O 17 Ti(Ta) 0.5 Nb 0.5 )2O7、(Zr 0.5 Hf 0.5 TiO4 and its corresponding high-entropy oxides, among others, possess different formation temperatures and melting points. On one hand, they hold promise for forming dense protective layers at different temperature ranges, achieving improved oxidation and ablation resistance over a wide temperature range in a relay-like manner. On the other hand, their synergistic effect with oxygen-free silicon-based ceramics is expected to yield silicate coatings (e.g., HfSiO4, HfZrO4) with lower oxygen ion or metal cation diffusion coefficients, thereby enabling ultra-high temperature ceramics to exhibit superior oxidation and ablation resistance over a wider temperature range. Furthermore, in this invention, the multi-component ultra-high temperature nano-composite ceramic matrix composite material does not require heat treatment above 1600℃, and the precursor does not react violently with fibers and interfaces. Therefore, the fibers in the preform are not damaged during preparation, resulting in superior mechanical properties.

[0011] In a preferred embodiment, the multi-element transition metal carbonitride phase has a face-centered cubic crystal structure, wherein two or more metal atoms from the transition metal elements Ti, Zr, Hf, Ta, Nb, Mo, and W share the cation lattice sites of the crystal in any atomic ratio, and C and / or N atoms occupy the anion lattice sites, forming a single-phase solid solution.

[0012] The multi-element transition metal carbonitride phase provided in this invention is preferably a single-phase solid solution. The single-phase solid solution has a uniform microstructure, higher hardness and modulus, and relatively lower thermal stress during service.

[0013] In a preferred embodiment, the oxygen-free silicon-based ceramic is selected from at least one of SiCN, SiBCN, Si3N4, and SiC.

[0014] In a preferred embodiment, the mass fraction of the multi-element ultra-high temperature nanocomposite ceramic is 0.1%-95%, more preferably 30%-90%.

[0015] In a preferred embodiment, in the multi-phase ultra-high temperature nanocomposite ceramic, the average grain size of at least one phase is 0.1-100 nm, preferably 10-80 nm.

[0016] In a preferred embodiment, the density of the multi-element ultra-high temperature nano-composite ceramic matrix has a density of 1-10.0 g / cm³. 3 Preferably, it is 2.0-4.0 g / cm³. 3 The open porosity of the multi-element ultra-high temperature nano-multiphase ceramic matrix composite material is 0.1-45%, preferably 1.0-20.0%.

[0017] This invention discloses a method for preparing a multi-component ultra-high temperature nano-composite ceramic matrix composite material, step one.

[0018] A complex of at least two metal elements selected from Ti, Zr, Hf, Nb, Ta, Mo and W is thoroughly mixed with a silicon-based polymer in an organic solvent and reacted to obtain a single-source precursor polymer impregnation solution.

[0019] Step Two

[0020] Porous fibers are impregnated in a single-source precursor polymer for a period of time, and then crosslinked and pyrolyzed to obtain a multi-component ultra-high temperature nano-multiphase ceramic matrix composite material. The composite material is densified by repeatedly performing the above impregnation-crosslinking-pyrolysis process.

[0021] The core idea of ​​the preparation method of this invention is to utilize the reaction between a precursor polymer and a transition metal element complex (unlike physical blending) to anchor transition metal atoms to the polymer macromolecular chain through chemical bonds, forming a single-source precursor polymer containing multiple metal elements. This is then combined with a polymer impregnation and pyrolysis method to composite with fibers. Simultaneously, during high-temperature heat treatment, multi-element ultra-high temperature nanoceramics are generated in situ, thereby obtaining a multi-element ultra-high temperature nanocomposite ceramic matrix composite material. The method of this invention causes minimal damage to the fibers, maintaining the integrity and mechanical strength of the fiber reinforcement, thus improving the mechanical properties of the composite material.

[0022] In a preferred embodiment, the silicon-based polymer is selected from polysilazane; the ligands of the complexes of transition metal elements Ti, Zr, Hf, Ta, Nb, Mo, and W are selected from dimethylamino and diethylamino groups.

[0023] In a preferred embodiment, a complex of at least two metal elements selected from Ti, Zr, Hf, Nb, Ta, Mo, and W is added to a silicon-based polymer in an organic solvent under a protective atmosphere. The organic solvent is selected from anhydrous xylene or anhydrous toluene, and the protective atmosphere is selected from argon or nitrogen.

[0024] In a preferred embodiment, the reaction temperature is -20 to 300°C, preferably 70 to 90°C, and more preferably 80°C, and the reaction time is 10 to 600 min, preferably 30 to 50 min, and more preferably 35 min.

[0025] In a preferred embodiment, the porous fiber body is selected from porous C / C composite materials with a density of 0.8-1.8 g / cm³. 3 The porosity is 8-40%.

[0026] In a preferred embodiment, in step two, the impregnation process involves first impregnating under vacuum conditions for 0.1-24 hours, preferably 0.3 hours, and then impregnating under a protective atmosphere for 0.1-48 hours, preferably 12 hours.

[0027] In a preferred embodiment, in step two, the crosslinking temperature is 50-300℃, preferably 250℃, the pyrolysis temperature is 800-1600℃, preferably 1100℃, and the pyrolysis time is 0.1-20h.

[0028] In a preferred embodiment, in step two, the number of cycles of repeated impregnation-crosslinking-pyrolysis is 1-18, preferably 6-10, and more preferably 8.

[0029] In this invention, in order to better analyze the performance of multi-component ultra-high temperature nanocomposite ceramic matrix composites, multi-component ultra-high temperature nanocomposite ceramics were prepared separately using the same raw materials and preparation process and studied. The preparation process includes the following steps:

[0030] (1) Weigh and mix the complex of at least two metal elements among Ti, Zr, Hf, Nb, Ta, Mo and W with the silicon-based polymer according to the stoichiometric ratio. In an inert atmosphere, dissolve the prepared chemical raw materials in an organic solvent, stir and mix evenly, then heat to allow the chemical reaction to occur, and finally separate the solvent by vacuum distillation or rotary evaporation to obtain a silicon-based mono-source precursor polymer containing at least two transition metal elements.

[0031] (2) Scheme 1: The precursor polymer obtained in step (1) is cross-linked, pyrolyzed, and subjected to high-temperature heat treatment under an inert atmosphere to complete the "polymer-ceramic" transformation and phase separation and crystallization process, thereby obtaining a multi-element ultra-high temperature nanocomposite ceramic. Scheme 2: The precursor polymer obtained in step (1) is cross-linked and pyrolyzed under an inert atmosphere to complete the "polymer-ceramic" transformation process, thereby obtaining an amorphous ceramic containing at least two transition metal elements; the amorphous ceramic is then subjected to high-temperature sintering to obtain a multi-element carbonitride / silicon carbonitride nanocomposite ceramic bulk.

[0032] The preparation steps of the above-mentioned multi-component ultra-high temperature nanocomposite ceramics are consistent with the preparation steps of multi-component ultra-high temperature nanocomposite ceramic matrix composites, and their preferred schemes are also consistent.

[0033] In step (1) of the preparation of the above-mentioned multi-component ultra-high temperature nanocomposite ceramics, as a preferred embodiment, the heating temperature is 30-150℃, preferably 80℃, and the heating reaction time is 10-600min, preferably 180min. The solvent removal method is vacuum distillation or rotary evaporation, and as a preferred embodiment, vacuum distillation at 80℃ is used.

[0034] In step (2) of the preparation of the above-mentioned multi-element ultra-high temperature nanocomposite ceramic, the inert gas is preferably nitrogen; the high-temperature heat treatment temperature is preferably 1300-1600℃, and the holding time is 5h. In step (2) of the preparation, the high-temperature sintering is spark plasma sintering, and the sintering conditions are: sintering furnace vacuum degree < 5Pa, sintering temperature 1500-2200℃, sintering pressure 0-200MPa, holding time 0-600min, and heating rate 5-800℃ / min. The open porosity of the multi-element ultra-high temperature nanocomposite ceramic is 0-30%, more preferably 0-10%.

[0035] Principles and advantages

[0036] This invention utilizes a polymer-to-ceramic conversion method to introduce a synthesized single-source precursor polymer into porous fibers via polymer impregnation pyrolysis (PIP). Then, through high-temperature heat treatment, in-situ self-generated multi-component ultra-high-temperature nanoceramics are produced, yielding a multi-component ultra-high-temperature nanocomposite ceramic matrix composite material. The multi-component ultra-high-temperature nanocomposite ceramic matrix composite material designed and prepared in this invention overcomes the damage to reinforcing fibers caused by traditional preparation methods, maintaining excellent oxidation and ablation properties while possessing good mechanical properties. Verification revealed that the prepared multi-component ultra-high-temperature nanocomposite ceramic matrix composite material achieves a flexural strength of 299 MPa, and after oxidation and ablation at 2000℃ for 60 s, its mass ablation rate is 3.8 mg / s, and its linear ablation rate is 0.00157 mm / s.

[0037] Compared to several methods commonly used in the preparation of ultra-high temperature ceramic matrix composites (i.e., SI, CVI, and RMI), this invention has the following main advantages:

[0038] (1) This method introduces transition metal elements (i.e., Ti, Zr, Hf, Nb, Ta, Mo, and W) through a chemical reaction between small molecules and silicon-based polymers. This allows for the uniform distribution and mixing of metal elements at the molecular level, thereby preparing (Ti a Zr b Hf c Nb d Ta e Mo f W g C x N 1-x Uniformly distributed nano-multiphase ceramic matrix composite material;

[0039] (2) The composite matrix prepared by this method is a nano-composite ceramic. On the one hand, by reducing the ceramic grain size, it is expected to further improve the mechanical properties of the composite material. On the other hand, when (Ti a Zr b Hf c Nb d Ta e Mo f W g C x N 1-x When the phase is uniformly distributed in the form of nanoparticles in oxygen-free silicon-based ceramics, a continuous phase can be formed even at a low volume fraction, which is expected to reduce (Ti) while ensuring ablation resistance. a Zr b Hf c Nb d Ta e Mo f W g C x N 1-x The content of the phase can reduce material density while saving costs;

[0040] (3) This method can flexibly control the oxygen-free silicon-based ceramics and (Ti) in nanocomposite ceramics by adjusting the proportion of small molecules participating in the chemical reaction. a Zr b Hf c Nb d Ta e Mo f W g C x N 1-x The actual content of (Ti) can be easily prepared. a Zr b Hf cNb d Ta e Mo f W g C x N 1-x Gradient nanocomposite ceramic matrix with continuously varying volume fraction can avoid the problem of thermal compatibility between multiple components;

[0041] (4) This method can prepare and control the chemical composition of multi-transition metal carbonitrides in the composite matrix by precisely adjusting the type and ratio of small molecules of metal complexes, thereby achieving controllable preparation of composite matrix and improving its antioxidant and ablation resistance.

[0042] (5) The heat treatment temperature of the present invention is generally 1000-1500℃, which realizes the preparation of multi-element ultra-high temperature nano-multiphase ceramic matrix composite material under lower temperature (≤1500℃). The fiber reinforcement is less damaged under this temperature range, so the mechanical properties and ablation resistance of ultra-high temperature ceramic matrix composite material can be improved simultaneously. Attached Figure Description

[0043] Figure 1 This is a flowchart of the preparation process of the multi-element ultra-high temperature nano-multiphase ceramic matrix composite material of the present invention.

[0044] Figure 2 The image shows the XRD pattern of the multi-component ultra-high temperature nano-composite ceramic powder obtained in Example 1 of this invention.

[0045] Figure 3 The image shows the XRD pattern of the multi-component ultra-high temperature nano-composite ceramic powder obtained in Example 2 of this invention.

[0046] Figure 4 This is a TEM image of the multi-component ultra-high temperature nanocomposite ceramic powder obtained in Example 2 of the present invention.

[0047] Figure 5 This is a TEM image of the multi-component ultra-high temperature nanocomposite ceramic powder obtained in Example 2 of the present invention.

[0048] Figure 6 The image shows the XRD pattern of the multi-component ultra-high temperature nano-composite ceramic powder obtained in Example 3 of this invention.

[0049] Figure 7 The image shows the XRD pattern of the multi-component ultra-high temperature nano-composite ceramic matrix obtained in Example 4 of this invention.

[0050] Figure 8 This is a SEM image of the multi-component ultra-high temperature nano-composite ceramic matrix composite material obtained in Example 4 of the present invention.

[0051] Figure 9 This is a macroscopic image of the multi-element ultra-high temperature nano-composite ceramic matrix composite material obtained in Example 5 of the present invention after ablation.

[0052] Figure 10 The image shows the three-point bending performance test results of the long strip-shaped multi-element ultra-high temperature nano-composite ceramic matrix obtained in Example 6 of this invention.

[0053] Figure 11 SEM image of the long strip-shaped multi-element ultra-high temperature nano-composite ceramic matrix composite material obtained in Example 6 of the present invention after fracture.

[0054] Figure 12 The XRD pattern of the amorphous ceramic powder obtained in Comparative Example 1 of this invention. Detailed Implementation

[0055] The following embodiments further illustrate this description. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the invention.

[0056] Example 1

[0057] According to 30(Ti) 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x The stoichiometric ratio of -70SiCN is as follows: 0.539 g of tetra(dimethylamino)titanium(IV), 0.643 g of tetra(dimethylamino)zirconium(IV), 0.853 g of tetra(dimethylamino)hafnium(IV), and 0.965 g of penta(dimethylamino)tantalum(IV) are dissolved in 15 ml of anhydrous toluene. 7.00 g of polynitrosilane (PSZ) is dissolved in 5 ml of anhydrous toluene. The two solutions are mixed thoroughly and stirred at room temperature for 30 min. The mixture is then heated to 80 °C and held for 3 h. After natural cooling, it is allowed to stand for 12 h. The anhydrous toluene is removed by vacuum distillation at 80 °C, yielding a silicon-based precursor polymer containing Ti, Zr, Hf, and Ta. The precursor polymer is then held at 1100 °C in nitrogen for 2 h to obtain an amorphous ceramic, which is subsequently tempered in nitrogen at 1600 °C for 5 h. This is denoted as 30(Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x -70SiCN-1600.

[0058] like Figure 2 As shown, the chemical composition obtained is (Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-xThe XRD pattern of the β-SiCN multiphase ceramic exhibits two sets of diffraction peaks. One set is typical diffraction peaks of metal carbonitrides with a face-centered cubic crystal structure, where Ti, Zr, Hf, and Ta atoms share the metal cation lattice sites, while C and N atoms occupy the anion lattice sites, forming a single solid solution. The other set consists of β-SiC and β-Si3N4 diffraction peaks. ICP elemental analysis showed that Ti:Zr:Hf:Ta = 1:1:0.98:0.97, demonstrating the effectiveness of this method in controlling the ratio of metal atoms.

[0059] Example 2

[0060] According to 70(Ti) 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x The stoichiometric ratio of -30SiCN is as follows: 1.258 g of tetrakis(dimethylamino)titanium(IV), 1.501 g of tetrakis(dimethylamino)zirconium(IV), 1.990 g of tetrakis(dimethylamino)hafnium(IV), and 2.251 g of penta(dimethylamino)tantalum(IV) are dissolved in 15 ml of anhydrous toluene. 3.00 g of PSZ is dissolved in 5 ml of anhydrous toluene. The two solutions are mixed thoroughly and stirred at room temperature for 30 min. The mixture is then heated to 80 °C and held for 3 h. After natural cooling, it is allowed to stand for 12 h. The anhydrous toluene is removed by vacuum distillation at 80 °C, yielding a silicon-based precursor polymer containing Ti, Zr, Hf, and Ta. The precursor polymer is then held at 1100 °C in nitrogen for 2 h to obtain an amorphous ceramic, which is subsequently tempered at 1600 °C in nitrogen for 5 h. This is denoted as 70(Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x -30SiCN-1600.

[0061] like Figure 3 As shown, the chemical composition obtained is (Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x The SiCN nanocomposite ceramic exhibits two sets of diffraction peaks in its XRD pattern. One set is typical of metal carbonitride diffraction peaks with a face-centered cubic crystal structure, where Ti, Zr, Hf, and Ta atoms share the metal cation lattice sites, while C and N atoms occupy the anion lattice sites, forming a single solid solution. The other set of diffraction peaks is SiCN diffraction peaks. Figure 4 TEM images show grain sizes ranging from 5-50 nm (Ti). 0.25 Zr 0.25Hf 0.25 Ta 0.25 C x N 1-x The unit cell parameter is 0.426 nm (e.g., Figure 5 ).

[0062] Example 3

[0063] According to 83(Ti) 0.1 Zr 0.3 Hf 0.5 Ta 0.1 C x N 1-x The stoichiometric ratio of -17SiCN was determined by dissolving 0.980 g of tetra(dimethylamino)titanium (Ⅳ), 3.509 g of tetra(dimethylamino)zirconium (Ⅳ), 7.756 g of tetra(dimethylamino)hafnium (Ⅳ), and 1.754 g of penta(dimethylamino)tantalum (Ⅳ) in 15 ml of anhydrous toluene. 3.00 g of PSZ was also dissolved in 5 ml of anhydrous toluene. The mixture was thoroughly mixed, stirred at room temperature for 30 min, heated to 80 °C and held for 3 h, allowed to cool naturally and stand for 12 h, and then the anhydrous toluene solution was removed by vacuum distillation at 80 °C to obtain a silicon-based precursor polymer containing Ti, Zr, Hf, and Ta. The precursor polymer was then held at 1100 °C for 2 h in nitrogen to obtain an amorphous ceramic.

[0064] The amorphous ceramic was ground into powder and placed in a graphite mold for spark plasma sintering. The vacuum degree in the furnace was <5 Pa. The temperature was increased to 2200℃ at a heating rate of 450℃ / min, held for 10 min, and the pressure was 70 MPa. Then, it was cooled to room temperature at a cooling rate of 100℃ / min to obtain a nano-multiphase ceramic bulk, denoted as 83(Ti). 0.1 Zr 0.3 Hf 0.5 Ta 0.1 C x N 1-x -17SiCN-SPS.

[0065] like Figure 6 As shown, the chemical composition obtained is (Ti 0.1 Zr 0.3 Hf 0.5 Ta 0.1 C x N 1-xA SiCN-based multiphase ceramic bulk sample with a porosity of 0.12% exhibits two sets of diffraction peaks in its XRD pattern. One set is typical of metal carbonitrides with a face-centered cubic crystal structure, where Ti, Zr, and Hf atoms share the metal cation lattice sites, while C and N atoms occupy the anion lattice sites, forming a single solid solution. The other set is SiCN diffraction peaks. The sample's hardness was 37.36 GPa and its modulus was 357.92 GPa, as tested by nanoindentation. Plasma ablation at 2200℃ for 60 s showed a mass ablation rate of -0.183 mg / s and a linear ablation rate of 0.033 μm / s. At 1500℃ for 40 h, the parabolic oxidation rate constant was 23.63 mg / s. 2 / (cm 4 ·h).

[0066] Example 4

[0067] According to 70(Ti) 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x The stoichiometric ratio of -30SiCN was determined by dissolving 2.516 g of tetrakis(dimethylamino)titanium(IV), 3.002 g of tetrakis(dimethylamino)zirconium(IV), 3.980 g of tetrakis(dimethylamino)hafnium(IV), and 4.502 g of penta(dimethylamino)tantalum(IV) in 20 ml of anhydrous toluene. 6.00 g of PSZ was also dissolved in 10 ml of anhydrous toluene. The two solutions were mixed thoroughly, stirred at room temperature for 30 min, heated to 80 °C and held for 3 h, and then allowed to cool naturally and stand for 12 h to obtain an impregnation solution containing a silicon-based precursor polymer of Ti, Zr, Hf, and Ta.

[0068] The porous C / C composite material was immersed in the precursor polymer under vacuum for 20 min, followed by argon gas filling and then impregnation for 24 h. The impregnated porous C / C composite material was then crosslinked and pyrolyzed at 1100 °C for 2 h under a nitrogen atmosphere. This impregnation and pyrolysis process was repeated 10 times to obtain a multi-component ultra-high temperature nano-multiphase ceramic matrix composite material, denoted as C / C-(Ti). 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x -SiCN.

[0069] like Figure 7 As shown, C / C-(Ti) is obtained. 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N1-x -SiCN composite material, through Figure 8 SEM images show that the voids between the carbon fiber bundles in the porous C / C composite material are all filled with ceramic. This multi-element ultra-high temperature nano-composite ceramic matrix composite material has a porosity of 15.9% and a density of 2.45 g / cm³. 3 Through plasma ablation, the ablation rate was 3.55 mg / s at 2000℃ for 60 s, and the linear ablation rate was 0.0225 mm / s.

[0070] Example 5

[0071] According to 70(Ti) 0.1 Zr 0.3 Hf 0.5 Ta 0.1 C x N 1-x The stoichiometric ratio of -30SiCN is as follows: 0.980 g of tetra(dimethylamino)titanium (Ⅳ), 3.509 g of tetra(dimethylamino)zirconium (Ⅳ), 7.756 g of tetra(dimethylamino)hafnium (Ⅳ), and 1.754 g of penta(dimethylamino)tantalum (Ⅳ) are dissolved in 15 ml of anhydrous toluene. 6.00 g of PSZ is dissolved in 5 ml of anhydrous toluene. The two solutions are mixed thoroughly and stirred at room temperature for 30 min. The mixture is then heated to 80 °C and held for 3 h. After natural cooling and standing for 12 h, the anhydrous toluene solution is removed by vacuum distillation at 80 °C to obtain a silicon-based precursor polymer containing Ti, Zr, Hf, and Ta. The precursor polymer is then held at 1100 °C for 2 h in nitrogen to obtain an amorphous ceramic.

[0072] According to 70(Ti) 0.1 Zr 0.3 Hf 0.5 Ta 0.1 C x N 1-x The stoichiometric ratio of -30SiCN is as follows: 0.980 g of tetrakis(dimethylamino)titanium(IV), 3.509 g of tetrakis(dimethylamino)zirconium(IV), 7.756 g of tetrakis(dimethylamino)hafnium(IV), and 1.754 g of penta(dimethylamino)tantalum(IV) are weighed and dissolved in 20 ml of anhydrous toluene. 6.00 g of PSZ is weighed and dissolved in 10 ml of anhydrous toluene. The two are mixed thoroughly and stirred at room temperature for 30 min. The mixture is then heated to 80 °C and held at that temperature for 3 h. After natural cooling, it is allowed to stand for 12 h to obtain an impregnation solution of a silicon-based precursor polymer containing Ti, Zr, Hf, and Ta.

[0073] The porous C / C composite material was immersed in the precursor polymer under vacuum for 20 min, followed by argon gas filling and then impregnation for 24 h. The impregnated porous C / C composite material was then crosslinked and pyrolyzed at 1100 °C for 2 h under a nitrogen atmosphere. This impregnation and pyrolysis process was repeated for 8 cycles to obtain a multi-component ultra-high temperature nano-multiphase ceramic matrix composite material, denoted as C / C-(Ti). 0.1 Zr 0.3 Hf 0.5 Ta 0.1 C x N 1-x -SiCN.

[0074] Get C / C-(Ti) 0.1 Zr 0.3 Hf 0.5 Ta 0.1 C x N 1-x -SiCN composite material with a porosity of 15.1% and a density of 2.52 g / cm³. 3 .like Figure 9 This multi-component ultra-high temperature nano-multiphase ceramic matrix composite material was ablated at 2000℃ for 60s via plasma ablation, with a mass ablation rate of 3.8mg / s and a linear ablation rate of 0.00157mm / s.

[0075] Example 6

[0076] According to 70(Ti) 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x The stoichiometric ratio of -30SiCN was determined by dissolving 2.516 g of tetrakis(dimethylamino)titanium(IV), 3.002 g of tetrakis(dimethylamino)zirconium(IV), 3.980 g of tetrakis(dimethylamino)hafnium(IV), and 4.502 g of penta(dimethylamino)tantalum(IV) in 20 ml of anhydrous toluene. 6.00 g of PSZ was also dissolved in 10 ml of anhydrous toluene. The two solutions were mixed thoroughly, stirred at room temperature for 30 min, heated to 80 °C and held for 3 h, and then allowed to cool naturally and stand for 12 h to obtain an impregnation solution containing a silicon-based precursor polymer of Ti, Zr, Hf, and Ta.

[0077] Long, porous C / C composite materials with dimensions of 3*4*50mm were immersed in a precursor polymer under vacuum for 20 minutes, followed by argon gas filling and impregnation for 24 hours. The impregnated porous C / C composite materials were then subjected to crosslinking and pyrolysis at 1100℃ for 2 hours under a nitrogen atmosphere. This impregnation and pyrolysis process was repeated 10 times to obtain long, multi-element, ultra-high temperature nanocomposite ceramic matrix composite materials, denoted as C / C-(Ti). 0.25 Zr0.25 Hf 0.25 Ta 0.25 C x N 1-x -SiCN.

[0078] The density of the above-mentioned elongated multi-element ultra-high temperature nano-composite ceramic matrix has a density of 2.6 g / cm³. 3 The porosity is 6.09%. For example... Figure 10 As shown, through three-point bending performance testing, this multi-element ultra-high temperature nano-composite ceramic matrix composite material exhibits pseudoplastic deformation, with a transverse fracture strength of 299.0 MPa. Figure 11 SEM images showed obvious carbon fiber pull-out on the fracture surface, which significantly enhanced the fracture strength of the material.

[0079] Comparative Example 1

[0080] According to 70(Ti) 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x The stoichiometric ratio of -30SiCN is as follows: 1.258 g of tetrakis(dimethylamino)titanium(IV), 1.501 g of tetrakis(dimethylamino)zirconium(IV), 1.990 g of tetrakis(dimethylamino)hafnium(IV), and 2.251 g of penta(dimethylamino)tantalum(IV) are dissolved in 15 ml of anhydrous toluene. 3.00 g of PSZ is dissolved in 5 ml of anhydrous toluene. The two solutions are mixed thoroughly and stirred at room temperature for 30 min. The mixture is then heated to 80 °C and held for 3 h. After natural cooling, it is allowed to stand for 12 h. The anhydrous toluene is removed by vacuum distillation at 80 °C, yielding a silicon-based precursor polymer containing Ti, Zr, Hf, and Ta. The precursor polymer is then held at 1100 °C in nitrogen for 2 h to obtain an amorphous ceramic, which is subsequently tempered at 1600 °C in nitrogen for 5 h. This is denoted as 70(Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x -30SiCN-1300.

[0081] like Figure 12 As shown, the prepared ceramic powder did not exhibit obvious characteristic peaks, indicating that the low heat treatment temperature prevented the amorphous ceramic after pyrolysis from crystallizing and separating into phases, and it remained in an amorphous state.

[0082] Comparative Example 2

[0083] According to 70(Ti) 0.25 Zr 0.25 Hf 0.25 Ta 0.25 Cx N 1-x The stoichiometric ratio of -30SiCN was determined by dissolving 2.516 g of tetrakis(dimethylamino)titanium(IV), 3.002 g of tetrakis(dimethylamino)zirconium(IV), 3.980 g of tetrakis(dimethylamino)hafnium(IV), and 4.502 g of penta(dimethylamino)tantalum(IV) in 20 ml of anhydrous toluene. 6.00 g of PSZ was also dissolved in 10 ml of anhydrous toluene. The two solutions were mixed thoroughly, stirred at room temperature for 30 min, heated to 80 °C and held for 3 h, and then allowed to cool naturally and stand for 12 h to obtain an impregnation solution containing a silicon-based precursor polymer of Ti, Zr, Hf, and Ta.

[0084] Long, porous C / C composite materials with dimensions of 3*4*50mm were immersed in a precursor polymer under vacuum for 20 minutes, followed by argon gas filling and impregnation for 24 hours. The impregnated porous C / C composite materials were then crosslinked and pyrolyzed at 1100℃ for 2 hours under a nitrogen atmosphere. This impregnation and pyrolysis process was repeated 10 times to obtain long, multi-element ultra-high temperature nanocomposite ceramic matrix composite materials. Finally, these multi-element ultra-high temperature nanocomposite ceramic matrix composite materials were heat-treated at 1500℃ for 5 hours under a nitrogen atmosphere. This composite material is denoted as C / C-(Ti 0.25 Zr 0.25 Hf 0.25 Ta 0.25 C x N 1-x -SiCN-1500℃.

[0085] The density of the above-mentioned elongated multi-element ultra-high temperature nano-composite ceramic matrix has a density of 2.58 g / cm³. 3 The porosity is 8.43%. Through three-point bending performance testing, this multi-component ultra-high temperature nano-multiphase ceramic matrix composite material exhibits pseudoplastic deformation, and its transverse fracture strength is 97.35 MPa.

[0086] Comparative Example 3

[0087] Long, porous C / C composite materials with dimensions of 3*4*50mm were immersed in pure polysilazane under vacuum for 20 minutes, followed by argon gas filling and then impregnation for 24 hours. The impregnated porous C / C composite materials were then crosslinked and pyrolyzed at 1100℃ for 2 hours under a nitrogen atmosphere. This impregnation and pyrolysis process was repeated for 6 cycles to obtain the long, porous composite material, denoted as C / C-SiCN.

[0088] The density of the above-mentioned strip-shaped composite material is 2.4 g / cm³. 3 The porosity is 1.8%. Its transverse fracture strength is 125.36 MPa, as determined by a three-point bending performance test.

[0089] Comparative Example 4

[0090] The density of the elongated porous C / C composite material with dimensions of 3*4*50mm is 1.64g / cm³. 3 The porosity is 30.23%. Through three-point bending performance testing, the transverse fracture strength of this porous C / C composite material is 103.35 MPa.

[0091] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a multi-component ultra-high temperature nano-composite ceramic matrix composite material, characterized in that: Step 1 A complex of at least two metal elements selected from Ti, Zr, Hf, Nb, Ta, Mo, and W is thoroughly mixed with a silicon-based polymer in an organic solvent and reacted to obtain a single-source precursor polymer impregnation solution; the silicon-based polymer is selected from polysilazane; the ligands of the complexes of transition metal elements Ti, Zr, Hf, Ta, Nb, Mo, and W are selected from dimethylamino and diethylamino groups; Step Two Porous fibers are impregnated in a single-source precursor polymer for a period of time, and then cross-linked and pyrolyzed to obtain a multi-component ultra-high temperature nano-multiphase ceramic matrix composite material. The composite material is densified by repeatedly performing the above impregnation-cross-linking-pyrolysis process. In step two, the impregnation process involves impregnating under vacuum, normal pressure, or pressure for 0.1-48 hours. In step two, the crosslinking temperature is 50-300℃, the pyrolysis temperature is 800-1600℃, and the pyrolysis time is 0.1-20 hours. In step two, the number of cycles of impregnation-crosslinking-pyrolysis is 1-18. The single-source precursor polymer is prepared by reacting silicon-based polymers with transition metal small molecules. After high-temperature pyrolysis, it is transformed into a multi-component ultra-high temperature nanocomposite ceramic composed of multi-component transition metal carbonitrides and oxygen-free silicon-based ceramics. The multi-component transition metal carbonitride has a face-centered cubic crystal structure. Two or more metal atoms among the transition metal elements Ti, Zr, Hf, Ta, Nb, Mo, and W share the cation lattice points of the crystal in any atomic ratio, and C and / or N atoms occupy the anion lattice points to form a single-phase solid solution with the chemical general formula (Ti a Zr b Hf c Nb d Ta e Mo f W g )C x N 1-x , where 0 < x < 1, a + b + c + d + e + f + g = 1, and at least two of a, b, c, d, e, f, g are not 0 simultaneously.

2. The method for preparing a multi-component ultra-high temperature nano-composite ceramic matrix according to claim 1, characterized in that: In step one, the reaction temperature is -20 to 300°C, and the reaction time is 10 to 600 min.

3. The method for preparing a multi-component ultra-high temperature nano-composite ceramic matrix according to claim 1, characterized in that: In the multi-element ultra-high temperature nanocomposite ceramic matrix, the mass fraction of multi-element transition metal carbonitride phases is 0.1%-95%, and the average grain size of at least one phase is ≤100 nm.

4. The method for preparing a multi-component ultra-high temperature nano-composite ceramic matrix according to claim 1, characterized in that: The porous fiber body is one of carbon fiber preform, silicon carbide fiber preform, or porous C / C, C / SiC, or SiC / SiC composite material preform, with an open porosity of 5% to 80%.

5. The method for preparing a multi-component ultra-high temperature nano-composite ceramic matrix according to claim 1, characterized in that: The density of the multi-element ultra-high temperature nano-composite ceramic matrix has an internal density of 1.0-10.0 g / cm³. 3 The porosity of the multi-element ultra-high temperature nano-multiphase ceramic matrix composite material is 0.1-45%.

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