A material suitable for extremely high temperature environments above 2700℃ and its preparation method

Abstract

This invention discloses a material suitable for extremely high temperature environments above 2700℃ and its preparation method, belonging to the field of material preparation technology. The material is a high-melting-point, high-temperature resistant carbide material, and the composition formula of the material is: Hf x Zr y Ti z C m A n Where A represents carbon vacancies, x = 50%–66.7%, y = 16.7%–50%, z = 16.7%–50%, m = 80%–100%, and n = 100%–m. This invention utilizes the aforementioned material suitable for extremely high-temperature environments above 2700℃ and its preparation method. The prepared material exhibits excellent ablation resistance under extreme wind tunnel conditions of 2700℃–2800℃ for 1000 seconds. Furthermore, the prepared carbides and high-melting-point oxides can be applied in the field of thermal protection against ultra-high-temperature ablation.

Description

Technical Field

[0001] This invention relates to the field of material preparation technology, and in particular to a material suitable for extremely high temperature environments above 2700℃ and its preparation method. Background Technology

[0002] With the continuous increase in the speed of hypersonic vehicles, more stringent requirements are being placed on the materials used in service. Ultra-high temperature ceramics, with their high melting point (>3000℃), good chemical stability, and ablation resistance, have attracted widespread attention. Compared to ordinary materials, ultra-high temperature ceramics exhibit excellent high-temperature oxidation resistance, low density, low coefficient of thermal expansion, and can maintain physical and chemical stability under extreme environments. Among ultra-high temperature ceramics, ZrC and HfC have extremely high melting points (>3500℃) and demonstrate excellent resistance to high-temperature oxidation. However, ZrO2 and HfO2 do not form porous oxides during oxidation, making them easily eroded and detached by high-speed airflow. For example, hafnium carbide begins to oxidize at approximately 800℃, forming a layer on the surface of HfO2 samples. This layer, acting as a diffusion barrier, breaks down and disrupts the sample's integrity, thereby promoting oxygen penetration and accelerating oxidation.

[0003] TiC itself possesses a high melting point and high heat of solution, while its oxidation product, TiO2, has a melting point of 1840℃. TiO2 can also combine with other oxidation products to form high-melting-point titanates. Compared to the commonly used high-temperature sealing phases SiO2 and B2O3, TiO2 and titanates exhibit superior crack-healing properties. Therefore, combining ZrC, HfC, and TiC to prepare medium-entropy carbide ceramics may exhibit higher mechanical properties and oxidation resistance, and is expected to provide better protection at temperatures above 2200℃. Currently, medium-entropy carbide ceramics have attracted much attention due to their extremely high melting point (>3000℃), high thermal conductivity, high hardness, and good oxidation resistance. These excellent properties make medium-entropy ceramics a potential candidate for applications under extreme conditions, and they have become the most promising candidate materials for hypersonic aerospace applications. However, methods for determining the composition ratio of medium-entropy ceramics, as well as the melting point and stability of their oxides after high-temperature ablation, are rarely reported. Summary of the Invention

[0004] The purpose of this invention is to provide a material suitable for extremely high temperature environments above 2700℃ and its preparation method, which addresses the problems of current materials for extremely high temperature environments being prone to low-temperature phase transformation cracking, having poor high-temperature ablation resistance, and having poor high-temperature stability of oxidation products. The prepared material is expected to be used for long-term ablation-resistant thermal protection in extreme environments above 2700℃.

[0005] To achieve the above objectives, this invention provides a material suitable for extremely high temperature environments above 2700℃. The material is a high-melting-point, high-temperature resistant carbide material, and its composition formula is: Hf x Zr y Ti z C m A n Where A represents a carbon vacancy. x =50%~66.7%, y =16.7%~50%, z =16.7%~50%, m =80%~100%, n =100%- m .

[0006] Preferably, the density ρ of the carbide material is 9.08 g / cm³. 3 ~10.31g / cm 3 The particle size is 300~500nm, and the oxygen content is 0.107wt.%~0.199wt.%.

[0007] This invention provides a method for preparing materials suitable for extremely high temperature environments above 2700℃, comprising the following steps: Step 1, designing MC-type multi-principal solid solution carbide ceramics using a cluster structure model representing the short program of local chemistry of solid solutions, and designing a highly stable carbide structural framework containing C vacancies [Hf x M 6-x C m A n This serves as the basis for carbide composition design;

[0008] Step 2: Embed the cluster structure model into first-principles calculations for performance prediction, and combine it with chemical reaction equilibrium equations to obtain the high-melting-point oxide framework;

[0009] Step 3: Calculate the oxygen diffusion rate of the high-melting-point oxide framework and HfO2 under high-temperature conditions;

[0010] Step 4: Use high-temperature stable oxidation products to design and determine the carbide composition ratio, and prepare carbide powder according to the obtained carbide composition ratio.

[0011] Preferably, in step one, [Hf] x M 6-x C m A n M represents two or more elements from Hf, Zr, Ti, Ta, and Nb.

[0012] Preferably, the high-melting-point oxide framework in step two includes Hf 19 Zr11 Ti2O 64 Hf4Zr3Ti1O 16 Hf4Zr4O 16 .

[0013] Preferably, the specific operation of the calculation in step three is to perform first-principles molecular dynamics simulation (AIMD) of oxides using the VASP software package, use projected plane wave pseudopotential (PAW) to describe the interaction between electrons and atomic nuclei, calculate the atomic motion law through the NVT ensemble model, and record the atomic mean square displacement (MSD).

[0014] Preferably, in step four, the mean square displacement (MSD) of atoms of different oxides is calculated to obtain the composition ratio and high-temperature stability of the oxides, which is used to guide the M atom ratio in the carbide structure, combined with the cluster composition formula [Hf x M 6-x C m A n Carbide ceramics with different composition ratios were obtained.

[0015] Preferably, the specific operation steps for preparing carbide powder by carbide composition ratio in step four are as follows: according to the designed carbide composition ratio, prepare the corresponding precursor, perform gradient heating in an air oven to complete the curing, and then perform pyrolysis in a graphite furnace to obtain the desired carbide powder.

[0016] Preferably, the gradient temperature increase is from room temperature to 250°C.

[0017] Preferably, the pyrolysis temperature is 1500℃~1800℃ and the pyrolysis time is 1~2h.

[0018] Carbides with a face-centered cubic β-NaCl structure have the highest melting points, especially HfC. Not only do the carbides have high melting points, but the oxidation product HfO2 also has a high melting point, making it promising for forming a dense and ultra-high temperature resistant oxide layer during oxidation. However, some literature indicates that carbides with an Hf:C ratio of 1:1 form a loose oxide layer during oxide formation, which is not conducive to hindering further oxidation. A denser oxide layer is obtained when some C atoms are missing, i.e., Hf:C > 1:1. Furthermore, according to the binary phase diagram of carbides, the element ratio at the highest melting point is often close to 6:5 (Hf:C). Therefore, multi-element alloying of carbides and oxide metal-side elements (Ti / Zr / Hf / Ta / Nb), as well as introducing vacancies and defects on the C side, can further improve the ultra-high temperature oxidation resistance of the material. Therefore, the cluster structure unit [Hf] can be designed using a short-program model of solid solution local chemistry. x M 6-x C m□ As the basis for carbide composition design.

[0019] Regarding oxidation products, HfO2 and ZrO2 have the same structure and phase transition law, and have a temperature higher than 2500. o C has a low melting point, making it a promising candidate for the oxide framework after carbide ablation. However, the oxides of Hf and Zr, HfO2 and ZrO2, exhibit three different structures from low to high temperatures, leading to volume changes and reducing the density of the high-temperature phase. This necessitates the use of other oxides to fill the voids. TiO2 has a lower melting point but can form a dense, fluid oxide layer, ensuring the stability of the oxide layer structure and, to some extent, preventing further diffusion of O. Therefore, Hf-Zr-Ti-C carbides with a reasonable composition ratio are expected to possess excellent resistance to ultra-high temperature oxidation. Furthermore, Hf, Zr, and Ti exhibit different reactivity with O; O tends to react with Ti first, followed by Zr and Hf. By reversing the chemical equilibrium equation, a carbide composition with Hf as the main component, Zr as the primary alloying element, and a small amount of Ti added under high temperature and pressure is derived, resulting in an oxide structure with HfO2 and ZrO2 as the main framework and TiO2 as a fluid, dense layer. By embedding cluster structure models into first-principles calculations for performance prediction, oxide frameworks with strong bond energies and high-temperature stability were obtained to aid in determining carbide composition. Furthermore, first-principles molecular dynamics simulations of the oxides were performed using the VASP software package. The atomic motion patterns at 2073 and 2773 K were calculated using the NVT ensemble model, and the mean square displacements (MSDs) of atoms were recorded, revealing the differences in high-temperature stability among different oxides.

[0020] Therefore, the present invention employs the above-mentioned material suitable for extremely high temperature environments above 2700℃ and its preparation method, which has the following advantages:

[0021] (1) By designing MC-type multi-principal solid solution carbide ceramics using a cluster structure model, a carbide structural framework with high stability [Hf] was obtained. x M 6-x C m A n Furthermore, the composition ratio of metal and non-metal elements in this framework is adjustable, making it applicable to a wide range of applications.

[0022] (2) A design concept of non-equimolar elemental composition is proposed. The composition ratio of the carbide skeleton is determined by combining the chemical reaction equilibrium equation and the high proportion of high melting point components. This can achieve synergistic anti-oxidation of multiple elements. The high melting point oxide skeleton has low melting point and TiO2 with a low oxygen diffusion coefficient (1.12×10). -13 m 2 ·s -1 The filling temperature (1800℃) can achieve a wide temperature range and long-term resistance to ablation.

[0023] (3) The first-principles molecular dynamics simulation of oxides was performed using the VASP software package. The atomic motion law at different temperatures was calculated using the NVT ensemble model, and the atomic mean square displacement (MSD) was recorded. This method can obtain the high-temperature stability differences of different oxides and prove that the designed oxides have better high-temperature stability.

[0024] (4) Use high-temperature stable oxidation products to design and assist in determining the composition ratio of carbides, so as to realize the integrated design from carbides to oxides and then to carbides.

[0025] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0026] Figure 1 This is an X-ray diffraction pattern of (Hf3Zr2Ti1)C5 ceramic powder prepared in Example 1 of the present invention, which describes a material suitable for extremely high temperature environments above 2700℃ and its preparation method.

[0027] Figure 2 This is a scanning electron microscope energy dispersive spectroscopy (SEM) spectrum of (Hf3Zr2Ti1)C5 ceramic powder prepared in Example 1 of the present invention, which describes a material suitable for extremely high temperature environments above 2700℃ and its preparation method.

[0028] Figure 3 The atomic mean square displacement (MSD) of various oxides in embodiments of the material and its preparation method for ultra-high temperature environments above 2700℃ in this invention is calculated using the NVT ensemble model at 2273K and 2773K. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0031] Example

[0032] This invention provides a material suitable for extremely high temperature environments above 2700℃. The material is a high-melting-point, high-temperature resistant carbide material, and its composition formula is: Hf x Zr y Ti z C m A n Where A represents a carbon vacancy, and the total percentage of all atoms in the metal atoms is 100%, and the total percentage of all atoms in the non-metal atoms is 100%, that is... x +y + z =100%, m + n =100%, x =50%~66.7%, y =16.7%~50%, z =16.7%~50%, m =80%~100%, n =100%- m .

[0033] The density of the carbide material is ρ = 9.08 g / cm³. 3 ~10.31g / cm 3 The particle size is 300~500nm, and the oxygen content is 0.107wt.%~0.199wt.%.

[0034] This invention provides a method for preparing materials suitable for extremely high temperature environments above 2700℃, comprising the following steps:

[0035] Step 1: Design MC-type multi-principal solid solution carbide ceramics using a cluster structure model representing the short program of local chemistry in solid solutions, and design a highly stable carbide structural framework containing C vacancies [Hf]. x M 6-x C m A n This serves as the basis for carbide composition design; [Hf x M 6-x C m A n In this model, M represents two or more elements selected from Hf, Zr, Ti, Ta, and Nb. This structural model allows for the description of the most basic components and structure of carbides, and enables the design of new compositions.

[0036] Step 2: Embed the cluster structure model into first-principles calculations for performance prediction. Combined with chemical reaction equilibrium equations and the properties of the oxide layer, select suitable host framework oxides and healing phase oxides. Based on the chemical reaction equilibrium equations and the different reactivity of Hf, Zr, Ti, and O, a high-melting-point oxide framework is obtained; the high-melting-point oxide framework includes Hf... 19 Zr 11 Ti2O 64 Hf4Zr3Ti1O 16 Hf4Zr4O 16 .

[0037] Step 3: By calculating the oxygen diffusion rate of the high-melting-point oxide framework and HfO2 under high-temperature conditions, we can determine that it has strong bond energy and high-temperature stability. The specific calculation operation is to perform first-principles molecular dynamics simulation (AIMD) of the oxide using the VASP software package, use the projected plane wave pseudopotential (PAW) to describe the interaction between electrons and atomic nuclei, calculate the atomic motion law at 2073K and 2773K using the NVT ensemble model, and record its atomic mean square displacement (MSD).

[0038] Step 4: Utilize high-temperature stable oxidation products to design and determine the carbide composition ratio, and prepare carbide powder based on the obtained carbide composition ratio. The mean square displacement (MSD) of atoms of different oxides is calculated to obtain the composition ratio and high-temperature stability of the oxides, which guides the M atom ratio in the carbide structure, combined with the cluster composition formula [Hf]. x M 6-x C m A n Carbide ceramics with different composition ratios were obtained. According to the designed carbide composition ratio, corresponding precursors were prepared. The precursors were subjected to a gradient heating from room temperature to 250°C in an air oven to complete the curing. Subsequently, they were pyrolyzed in a graphite furnace at 1500°C~1800°C for 1-2 hours to obtain the desired carbide powder.

[0039] Example 1

[0040] This invention provides a method for preparing materials suitable for extremely high temperature environments above 2700℃, comprising the following steps:

[0041] Step 1: Design MC-type multi-principal carbide ceramics using a cluster structure model representing the short program of local chemistry in solid solutions, and construct the cluster composition formula [Hf] for vacancy-ordered carbide solid solutions. x M 6-x C m A n This model serves as the basis for designing carbide compositions. Here, C represents carbon atoms, M represents Hf and alloying elements (M = Zr, Ti), and A represents carbon vacancies, ideally one in total. This structural model allows for the description of the most basic composition and structure of carbides, and enables the design of new compositions.

[0042] Step 2: Selection and addition of alloying elements for M. HfO2 and ZrO2 have the same structure and phase transformation law, and have melting points above 2500℃, so they are expected to serve as oxide skeletons after carbide ablation. However, since HfO2 (ZrO2) undergoes allotropic transformations in different temperature ranges, it easily causes loose pores in the high-temperature cubic structure of HfO2 (ZrO2). Therefore, it is necessary to introduce Ti to form TiO2, an oxide product with a lower melting point but good compactness and oxidation resistance, to fill the loose and heat-resistant oxide physical skeleton. Combining the chemical reaction equilibrium equation and the difference in the reactivity of Hf, Zr, Ti and O, the carbide composition with Hf as the main component, Zr as the main alloying element, and a small amount of Ti added under high temperature and high pressure is deduced from the chemical equilibrium equation. This yields an oxide structure with HfO2 and ZrO2 as the main skeleton, a small amount of dissolved Ti, and TiO2 as a flowing dense layer, with Hf as the high-melting-point oxide skeleton. 19 Zr 11 Ti2O 64 .

[0043] Step 3: First-principles molecular dynamics simulations (AIMD) of oxides were performed using the VASP software package. Projected plane wave pseudopotentials (PAW) were used to describe the interaction between electrons and atomic nuclei. The electronic structure of each element was treated as: C-2s 2 2p 2 O-2s 2 2p 4 Ti-3p 6 3D 2 4s 2 Zr-4s 2 4p 6 5s 2 4d 2 Hf-5p 6 6s 2 5d 2 The plane wave cutoff energy was set to 600 eV. The convergence criterion for the Hellmann-Feynman force was 0.03 eV / Å, and the energy convergence criterion was 1*10-5 eV. The atomic motion of the model at 2273 K and 2773 K was calculated using the NVT ensemble, and the mean square displacement (MSD) of the atoms was recorded.

[0044] Step 4: Utilize high-temperature stable oxidation products to design and determine the carbide composition. The mean square atomic displacement (MSD) and Hf of the oxides are calculated. 19 Zr 11 Ti2O 64Both exhibit significantly lower MSD of O. By adjusting the M ratio in the oxide corresponding to the carbide, (Hf3Zr2Ti1)C5 carbide can be obtained, which simultaneously possesses Ti filling and stable Hf. 19 Zr 11 Ti2O 64 The oxide skeleton has higher high-temperature oxidation resistance.

[0045] Based on the designed (Hf3Zr2Ti1)C5, a corresponding precursor was prepared. The precursor was then cured in an air oven with a gradient temperature increase from room temperature to 250°C. Subsequently, it was pyrolyzed in a graphite furnace at 1500°C for 2 hours to obtain the desired carbide powder.

[0046] The (Hf3Zr2Ti1)C5 ceramic powder prepared in this embodiment was subjected to phase analysis using XRD diffraction. Figure 1 As shown, the material is mainly composed of a single phase (Hf3Zr2Ti1)C5, without any other impurity phases, resulting in a good solid solution effect for the single-phase ceramic.

[0047] The (Hf3Zr2Ti1)C5 ceramic powder prepared in this embodiment was tested using scanning electron microscopy (SEM), and its morphology and composition distribution are shown below. Figure 2 As shown, the average grain size of the ceramic powder is between 300 and 450 nm, with no element segregation and the elements achieving micron-level uniform mixing.

[0048] Figure 3 First-principles molecular dynamics simulations were performed on various oxides designed for this study. The mean square atomic displacements (MSDs) at 2273 K and 2773 K were calculated using the NVT ensemble model. The results show that (Hf3Zr2Ti1)C5 has a lower MSD than HfO2 and ZrO2 at high temperatures, indicating better stability and better protection against ultra-high temperature oxidation.

[0049] The density of (Hf3Zr2Ti1)C5 powder, as measured by a true density meter, is 9.321 g / cm³. 3 The oxygen content of (Hf3Zr2Ti1)C5 powder can be measured to be 0.107 wt. using a nitrogen and oxygen analyzer.

[0050] The carbides designed in this embodiment were used to prepare composite materials, and the C... f Plasma wind tunnel ablation tests were conducted on / (Hf3Zr2Ti1)C5 at a heat flux density of 3.6 MW / m³. 2At a stagnation pressure of 5 kPa and an ablation temperature of 2973 K (2700℃) for 1000 s, the linear ablation rate was 5.1 × 10⁻⁴ mm / s. This indicates that the loss of our composite material after prolonged ablation is almost negligible. This is better than C f The / HfC composite material has ablation performance that is more than 10 times better and has excellent resistance to ultra-high temperature ablation.

[0051] Example 2

[0052] This invention provides a method for preparing materials suitable for extremely high temperature environments above 2700℃, comprising the following steps:

[0053] Step 1: Design MC-type multi-principal carbide ceramics using a cluster structure model representing the short program of local chemistry in solid solutions, and construct the cluster composition formula [Hf] for vacancy-ordered carbide solid solutions. x M 6-x C m A n This model serves as the basis for designing carbide compositions. Here, C represents carbon atoms, M represents Hf and alloying elements (M = Zr, Ti), and A represents carbon vacancies, ideally one in total. This structural model allows for the description of the most basic composition and structure of carbides, and enables the design of new compositions.

[0054] Step 2: Selection and addition of alloying elements (M). HfO2 and ZrO2 have the same structure and phase transformation law, and have melting points above 2500℃, so they are expected to serve as oxide skeletons after carbide ablation. However, since HfO2 (ZrO2) undergoes allotropic transformations in different temperature ranges, it easily causes loose pores in the high-temperature cubic structure of HfO2 (ZrO2). Therefore, it is necessary to introduce Ti to form TiO2, an oxide product with a lower melting point but good compactness and oxidation resistance, to fill the loose and heat-resistant oxide physical skeleton. Combining the chemical reaction equilibrium equation and the difference in the reactivity of Hf, Zr, Ti and O, the carbide composition with Hf as the main component, Zr as the main alloying element, and a small amount of Ti added under high temperature and high pressure is deduced from the chemical equilibrium equation. This yields an oxide structure with HfO2 and ZrO2 as the main skeleton, a small amount of dissolved Ti, and TiO2 as a flowing dense layer. The high-melting-point oxide skeleton is HfZrO4.

[0055] Step 3: First-principles molecular dynamics simulations (AIMD) of oxides were performed using the VASP software package. Projected plane wave pseudopotentials (PAW) were used to describe the interaction between electrons and atomic nuclei. The electronic structure of each element was treated as: C-2s 2 2p 2 O-2s 2 2p 4Ti-3p 6 3D 2 4s 2 Zr-4s 2 4p 6 5s 2 4d 2 Hf-5p 6 6s 2 5d 2 The plane wave cutoff energy was set to 600 eV. The convergence criterion for the Hellmann-Feynman force was 0.03 eV / Å, and the energy convergence criterion was 1*10-5 eV. The atomic motion of the model at 2273 K and 2773 K was calculated using the NVT ensemble, and the mean square displacement (MSD) of the atoms was recorded.

[0056] Step 4: Use high-temperature stable oxidation products to design and determine the carbide composition ratio. By calculating the atomic mean square displacement (MSD) of the oxides, HfZrO4 has the lowest MSD of O. By determining the M ratio of the oxides to the corresponding carbides, (Hf3Zr3)C5 carbides can be obtained. However, due to the allotropic transformation of the oxides in different temperature ranges, it is easy to cause loose pores in the high-temperature cubic structure (Hf,Zr)O2.

[0057] Based on the designed (Hf3Zr3)C5, a corresponding precursor was prepared and cured in an air oven by gradient heating from room temperature to 250°C. Subsequently, it was pyrolyzed in a graphite furnace at 1500°C for 2 hours to obtain the desired carbide powder.

[0058] The calculation results show that (Hf3Zr3)C5 has a lower atomic mean square displacement (MSD) than HfO2 and ZrO2 at high temperatures, and has better stability and better protection against ultra-high temperature oxidation.

[0059] The (Hf3Zr3)C5 ceramic powder synthesized under these conditions is a pure phase with an average grain size between 350 and 500 nm. The density of the (Hf3Zr3)C5 powder, measured by a true density meter, is 9.522 g / cm³. 3 The oxygen content of (Hf3Zr3)C5 powder can be measured to be 0.199 wt.% using a nitrogen and oxygen analyzer.

[0060] Example 3

[0061] This invention provides a method for preparing materials suitable for extremely high temperature environments above 2700℃, comprising the following steps:

[0062] Step 1: Design MC-type multi-principal carbide ceramics using a cluster structure model representing the short program of local chemistry in solid solutions, and construct the cluster composition formula [Hf] for vacancy-ordered carbide solid solutions. x M 6-x C m A n This model serves as the basis for designing carbide compositions. Here, C represents carbon atoms, M represents Hf and alloying elements (M = Zr, Ti), and A represents carbon vacancies, ideally one in total. This structural model allows for the description of the most basic composition and structure of carbides, and enables the design of new compositions.

[0063] Step 2: Selection and addition of alloying elements for M. HfO2 and ZrO2 have the same structure and phase transformation law, and have melting points above 2500℃, so they are expected to serve as oxide skeletons after carbide ablation. However, since HfO2 (ZrO2) undergoes allotropic transformations in different temperature ranges, it easily causes loose pores in the high-temperature cubic structure of HfO2 (ZrO2). Therefore, it is necessary to introduce Ti to form TiO2, an oxide product with a lower melting point but good compactness and oxidation resistance, to fill the loose and heat-resistant oxide physical skeleton. Combining the chemical reaction equilibrium equation and the difference in the reactivity of Hf, Zr, Ti and O, the carbide composition with Hf as the main component, Zr as the main alloying element, and a small amount of Ti added under high temperature and high pressure is deduced from the chemical equilibrium equation. This yields an oxide structure with HfO2 and ZrO2 as the main skeleton, a small amount of dissolved Ti, and TiO2 as a flowing dense layer, with Hf as the high-melting-point oxide skeleton. 16 Zr2Ti4O 64 .

[0064] Step 3: First-principles molecular dynamics simulations (AIMD) of oxides were performed using the VASP software package. Projected plane wave pseudopotentials (PAW) were used to describe the interaction between electrons and atomic nuclei. The electronic structure of each element was treated as: C-2s 2 2p 2 O-2s 2 2p 4 Ti-3p 6 3D 2 4s 2 Zr-4s 2 4p 6 5s 2 4d 2 Hf-5p 6 6s 2 5d 2The plane wave cutoff energy was set to 600 eV. The convergence criterion for the Hellmann-Feynman force was 0.03 eV / Å, and the energy convergence criterion was 1*10-5 eV. The atomic motion of the model at 2273 K and 2773 K was calculated using the NVT ensemble, and the mean square displacement (MSD) of the atoms was recorded.

[0065] Step 4: Utilize high-temperature stable oxidation products to design and determine the carbide composition. The mean square atomic displacement (MSD) and Hf of the oxides are calculated. 16 Zr 12 Ti4O 64 Both exhibit significantly lower MSD of O. By adjusting the M ratio in the oxide corresponding to the carbide, (Hf4Zr1Ti1)C5 carbide can be obtained, which simultaneously possesses Ti filling and stable Hf. 16 Zr 12 Ti4O 64 The oxide skeleton exhibits high high-temperature oxidation resistance.

[0066] Based on the designed (Hf4Zr1Ti1)C5, a corresponding precursor was prepared. The precursor was then cured in an air oven with a gradient temperature increase from room temperature to 250°C. Subsequently, it was pyrolyzed in a graphite furnace at 1500°C for 2 hours to obtain the desired carbide powder.

[0067] The calculation results show that (Hf4Zr1Ti1)C5 has a lower atomic mean square displacement (MSD) than HfO2 and ZrO2 at high temperatures, and has better stability and better protection against ultra-high temperature oxidation.

[0068] The (Hf4Zr1Ti1)C5 ceramic powder synthesized under these conditions is a pure phase with an average grain size between 350 and 500 nm. The density of the (Hf4Zr1Ti1)C5 powder, measured by a true density meter, is 10.14 g / cm³. 3 The oxygen content of (Hf4Zr1Ti1)C5 powder can be measured to be 0.187 wt. using a nitrogen and oxygen analyzer.

[0069] Therefore, this invention employs the aforementioned material and its preparation method suitable for extremely high temperature environments above 2700℃, and designs MC-type multi-principal solid solution carbide ceramics using a cluster structure model, thereby obtaining a carbide structural framework [Hf] with high stability. x M 6-x C m A n Furthermore, the composition ratio of metal and non-metal elements in this framework is adjustable, making it widely applicable. The design of high-temperature stable oxidation products is used to assist in determining the carbide composition ratio, achieving integrated design from carbide to oxide and then to carbide.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a material suitable for extremely high temperature environments above 2700℃, characterized in that: The material is a high-melting-point, high-temperature resistant carbide material, and its composition formula is: Hf x Zr y Ti z C m A n Where A represents a carbon vacancy. x =50%~66.7%, y =16.7%~50%, z =16.7%~50%, x + y + z =100%, m =80%~100%, n =100%- m ; The density of the carbide material is ρ = 9.08 g / cm³. 3 ~10.31g / cm 3 The particle size is 300~500nm, and the oxygen content is 0.107wt.%~0.199wt.%. The above-described method for preparing a material suitable for extremely high temperature environments above 2700℃ includes the following steps: Step 1: Design MC-type multi-principal solid solution carbide ceramics using a cluster structure model representing the short program of local chemistry in solid solutions, and design a highly stable carbide structural framework containing C vacancies [Hf]. x M 6-x C m A n This serves as the basis for carbide composition design; Step 2: Embed the cluster structure model into first-principles calculations for performance prediction, and combine it with chemical reaction equilibrium equations to obtain the high-melting-point oxide framework; Step 3: Calculate the oxygen diffusion rate of the high-melting-point oxide framework and HfO2 under high-temperature conditions; Step 4: Use high-temperature stable oxidation products to design and determine the carbide composition ratio, and prepare carbide powder according to the obtained carbide composition ratio.

2. The method for preparing a material suitable for extremely high temperature environments above 2700℃ according to claim 1, characterized in that: The [Hf] in step one x M 6-x C m A n M represents two or more elements from Hf, Zr, and Ti.

3. The method for preparing a material suitable for extremely high temperature environments above 2700℃ according to claim 1, characterized in that: The high-melting-point oxide framework in step two includes Hf 19 Zr 11 Ti2O 64 Hf4Zr3Ti1O 16 Hf4Zr4O 16 .

4. The method for preparing a material suitable for extremely high temperature environments above 2700℃ according to claim 1, characterized in that: The specific calculation operation in step three involves performing first-principles molecular dynamics simulation (AIMD) of oxides using the VASP software package, describing the interaction between electrons and atomic nuclei using projected plane wave pseudopotential (PAW), calculating the atomic motion laws using the NVT ensemble model, and recording the atomic mean square displacement (MSD).

5. The method for preparing a material suitable for extremely high temperature environments above 2700℃ according to claim 1, characterized in that: In step four, the mean square displacement (MSD) of atoms of different oxides is calculated to obtain the composition ratio and high-temperature stability of the oxides, which is used to guide the M atom ratio in the carbide structure, combined with the cluster composition formula [Hf]. x M 6-x C m A n Carbide ceramics with different composition ratios were obtained.

6. The method for preparing a material suitable for extremely high temperature environments above 2700℃ according to claim 1, characterized in that: The specific steps for preparing carbide powder by carbide composition ratio in step four are as follows: According to the designed carbide composition ratio, prepare the corresponding precursor, perform gradient heating in an air oven to complete the curing, and then perform pyrolysis in a graphite furnace to obtain the desired carbide powder.

7. The method for preparing a material suitable for extremely high temperature environments above 2700℃ according to claim 6, characterized in that: The temperature gradient is from room temperature to 250°C.

8. The method for preparing a material suitable for extremely high temperature environments above 2700℃ according to claim 6, characterized in that: The pyrolysis temperature is 1500℃~1800℃, and the pyrolysis time is 1-2h.

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