Ultrahigh-temperature refractory material and preparation method thereof

Abstract

The invention relates to the technical field of refractory materials, in particular to an ultrahigh-temperature refractory material and a preparation method thereof. The ultrahigh-temperature refractory material comprises an ablation-resistant outer layer and an anti-oxidation inner layer, wherein the ablation-resistant outer layer is composed of a composite material containing a carbide ceramic matrix and first reinforced fibers; the carbide ceramic matrix is composed of a solid solution formed by the effect of five carbides of HfC, ZrC, TaC, NbC and TiC which are equal in mass; the first reinforcing fibers are chopped SiC fibers. According to the ultrahigh-temperature refractory material provided by the invention, the density of the ultrahigh-temperature refractory material is improved, and the comprehensive performance of the ultrahigh-temperature refractory material in the aspects of strength, toughness, oxidation resistance and the like is improved.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, specifically to an ultra-high temperature refractory material and its preparation method. Background Technology

[0002] Ultra-high temperature refractory materials refer to refractory materials that can operate normally at temperatures above 2000℃. With the accelerating pace of industrialization, high-temperature equipment is emerging and becoming increasingly complex in numerous fields. In the aerospace industry, engine components must withstand extremely high temperatures and complex thermal stresses to ensure the efficient and stable operation of aircraft. In the space industry, spacecraft face extreme high-temperature tests when entering the atmosphere and space environment, placing near-stringent demands on the high-temperature resistance of materials. In the military industry, weapons and equipment generate intense high temperatures during launch and use, making ultra-high temperature refractory materials crucial for ensuring the performance and reliability of equipment. Furthermore, in fields such as electrode crucibles used in high-temperature metal smelting and continuous casting, the requirements for material refractoriness are also increasing, with some specialized fields even requiring materials with melting points above 3000℃.

[0003] Existing methods for preparing ultra-high temperature refractory materials often contain numerous pores and defects. In powder metallurgy, the bonding between powder particles is often insufficient. Although particles fuse to some extent during sintering, it is difficult to completely eliminate interparticle gaps. Furthermore, improper pressure control or inadequate mold design during molding can lead to microcracks and other defects within the material. These pores and defects reduce the material's density, causing stress to concentrate at defective sites when subjected to external forces or high temperatures, initiating and propagating cracks. This results in a decrease in the material's strength and hardness, failing to meet the stringent performance requirements of ultra-high temperature environments. Current ultra-high temperature refractory materials still exhibit significant deficiencies in terms of comprehensive properties such as strength, toughness, and oxidation resistance. It is difficult for a single material to simultaneously possess high strength, high toughness, and good oxidation resistance. Based on this, this invention proposes an ultra-high temperature refractory material and its preparation method. Summary of the Invention

[0004] This invention proposes an ultra-high temperature refractory material and its preparation method, which improves the density of the ultra-high temperature refractory material and enhances its comprehensive performance in terms of strength, toughness, and oxidation resistance.

[0005] The technical solution of the present invention is as follows: In a first aspect, the present invention proposes an ultra-high temperature refractory material, comprising an ablation-resistant outer layer and an oxidation-resistant inner layer; wherein the ablation-resistant outer layer is composed of a composite material comprising a carbide ceramic matrix and a first reinforcing fiber; the carbide ceramic matrix is ​​composed of a solid solution formed by the effect of five carbides of equal mass: HfC, ZrC, TaC, NbC and TiC; and the first reinforcing fiber is a short-cut SiC fiber.

[0006] As a further technical solution, the antioxidant inner layer is composed of HfB2, ZrB2 and SiC, with a weight ratio of 10-80:10-80:10-30.

[0007] As a further technical solution, the mass fraction of the first reinforcing fiber is 1%-10% of the total mass of the ablation-resistant outer layer.

[0008] Secondly, this invention proposes a method for preparing ultra-high temperature refractory materials, comprising the following steps: S1. Preparation of precursor solution: An oxygen-free silicon-based polymer precursor and an organometallic compound containing Hf, Zr, Ta, Nb, and Ti are dissolved together in an organic solvent to form a single-source precursor solution; S2. Slurry preparation: The single-source precursor solution is mixed and ball-milled with the ceramic powder and reinforcing fiber of the corresponding layer to prepare the inner layer slurry and the outer layer slurry; S3. Construction of layered green blanks: Each layer of slurry is made into a green blank using the tape casting method, and then stacked in the order of inner and outer layers. After cold isostatic pressing, a layered green blank is obtained. S4. Precursor transformation: The layered green body is heated to 1000-1400℃ at a heating rate of 1-10℃ / min under an inert atmosphere and held for 0.5-2h to decompose the polymer precursor and transform it into nano-multiphase ceramic. S5. Densification sintering: The preform after precursor conversion is placed in a spark plasma sintering furnace for spark plasma sintering, and then cooled with the furnace to obtain the ultra-high temperature refractory material.

[0009] This invention employs a method of co-dissolving an oxygen-free silicon-based polymer precursor with a metal-organic compound containing Hf, Zr, Ta, Nb, and Ti in an organic solvent to form a single-source precursor solution. This single-source precursor solution provides a homogeneous compositional basis for subsequent slurry preparation. During slurry preparation, the single-source precursor solution is ball-milled with the corresponding ceramic powder and reinforcing fibers. The precursor solution not only uniformly coats the ceramic powder and reinforcing fibers, ensuring their uniform dispersion in the slurry, but also causes the polymer components in the precursor solution to decompose during the subsequent precursor conversion process, forming nano-multiphase ceramics that fill the voids between the ceramic powder and fibers, enhancing the bonding force between the powder and fibers and improving the material's density and mechanical properties. This synergistic approach of precursor solution and slurry preparation ensures the uniformity of composition and the density of the structure of each layer of the material.

[0010] This invention utilizes a tape casting method to separately form green strips from each layer of slurry, which are then stacked in an inner-outer layer sequence and subjected to cold isostatic pressing to obtain a layered green body. The tape casting method allows for precise control of the thickness of each green strip, ensuring the uniformity of the layered structure. Cold isostatic pressing further improves the density and strength of the green body, resulting in a tight bond between the layers. During the precursor conversion process, the layered green body is heated to a specific temperature at a controlled heating rate under an inert atmosphere and held at that temperature, causing the polymer precursor to decompose and transform into nano-multiphase ceramics. This synergy between the construction of the layered green body and the precursor conversion allows the nano-multiphase ceramics to form uniformly within the layered structure, filling the pores in the green body and further improving the material's density and performance stability. Simultaneously, the inert atmosphere protection prevents oxidation during the high-temperature conversion process, ensuring the material's purity and performance.

[0011] This invention involves placing the precursor-converted green body in a spark plasma sintering furnace for spark plasma sintering. Spark plasma sintering is characterized by rapid heating, short sintering time, and the ability to apply high pressure. During the sintering process, the green body is first heated to a specific temperature at a certain rate under a nitrogen atmosphere and a certain pressure is applied to initially densify it. Then, the temperature is rapidly increased to the target temperature, and the pressure is increased to a higher value within a short time to further promote densification. This synergistic effect of rapid heating and high pressure can inhibit grain growth, obtain a fine and uniform grain structure, and improve the strength and hardness of the material. At the same time, the plasma generated by spark plasma sintering can activate the material surface, promote the formation of sintering necks, and enhance the bonding force between particles, thereby improving the density and overall performance of the material.

[0012] As a further technical solution, the oxygen-free silicon-based polymer precursor includes one or two of vinyl polycarbosilane and polycarbosilane, with a number-average molecular weight of 800-2000; the organometallic compound includes one or more of the acetylacetonates, alkoxides, and carboxylates of various metals; and the organic solvent includes one or more of xylene, n-hexane, and tetrahydrofuran.

[0013] As a further technical solution, the slurry ball milling process uses zirconia balls with a ball-to-material ratio of 2-5:1 and a milling time of 36-48 hours.

[0014] As a further technical solution, in step S3, the thickness of the green strip is 0.1-2mm; the pressure of the cold isostatic pressing is 100-200MPa, and the holding time is 1-5min.

[0015] As a further technical solution, in step S4, the inert atmosphere is high-purity argon or nitrogen.

[0016] As a further technical solution, the precursor conversion includes the following steps: heating from room temperature to 600°C at a heating rate of 1°C / min, heating from 600°C to 1200°C at a heating rate of 3°C / min, and holding at that temperature for 1 hour.

[0017] As a further technical solution, the plasma sintering includes the following steps: under a nitrogen atmosphere, the temperature is increased to 1400℃ at a pressure of 10-12MPa at a rate of 150℃ / min; after reaching 1400℃, the pressure is increased to 30-50MPa within 1-3 minutes, and then the temperature is increased to 1900-2100℃ at a rate of 100-200℃ / min, and held for 10-20 minutes.

[0018] The working principle and beneficial effects of this invention are as follows: In the ultra-high temperature refractory material of this invention, the ablation-resistant outer layer of the carbide ceramic matrix is ​​composed of a solid solution formed by the effects of five carbides: HfC, ZrC, TaC, NbC, and TiC, in equal masses. Different carbides possess their own unique physical and chemical properties; for example, HfC and TaC have extremely high melting points, ZrC and NbC exhibit good oxidation resistance and thermal stability, while TiC possesses good mechanical properties. After forming a solid solution, they achieve structural homogenization and performance optimization at the atomic scale. The various carbides complement and synergistically interact, enabling the material to maintain a stable structure and performance under ultra-high temperature conditions, effectively resisting ablation and thermal shock.

[0019] This invention introduces chopped SiC fibers as the first reinforcing fiber into the ablation-resistant outer layer. SiC fibers possess high strength, high modulus, and excellent high-temperature resistance. When the material is subjected to external forces and cracks develop, the SiC fibers can exert a toughening effect through bridging and pull-out mechanisms. The bridging mechanism refers to the fiber bridging across the crack, preventing further crack propagation and consuming the energy required for crack propagation; the pull-out mechanism involves the fiber being pulled out of the matrix during crack propagation, which also requires a significant amount of energy, thereby improving the fracture toughness of the material. This fiber toughening method, combined with the strength of the carbide ceramic matrix, enables the material to possess both high strength and good toughness, effectively resisting crack initiation and propagation, and improving the reliability of the material.

[0020] The anti-oxidation inner layer consists of HfB2, ZrB2, and SiC. HfB2 and ZrB2 are both high-melting-point, high-hardness borides, exhibiting excellent oxidation resistance and high-temperature stability. They can form a dense oxide film at high temperatures, preventing further oxygen intrusion. SiC possesses good chemical stability and high-temperature strength, while its oxidation product, SiO2, can form a glassy protective layer on the material surface, further enhancing oxidation resistance. These three components work synergistically: HfB2 and ZrB2 provide the primary high-temperature anti-oxidation barrier, while SiC assists in enhancing the anti-oxidation effect and improving the overall strength of the material, jointly ensuring the material's performance under high-temperature oxidizing conditions. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Polycarbosilane was purchased from Suzhou Serifi Ceramic Fiber Co., Ltd., with a number average molecular weight of 1395.

[0022] Example 1 This embodiment provides a method for preparing ultra-high temperature refractory materials, including the following steps: S1. Preparation of precursor solution: Weigh 20.0 g of polycarbosilane with a number average molecular weight (Mn) of 1395 and add it to 100 mL of xylene. Stir at room temperature until completely dissolved. Then add 4.12 g of hafnium acetylacetonate, 3.87 g of zirconium acetylacetonate, 4.96 g of tantalum acetylacetonate, 4.26 g of niobium acetylacetonate, and 3.16 g of titanium acetylacetonate in sequence. Heat the reaction system to 80 °C and stir at 300 rpm for 6 h at this temperature. Cool to room temperature to obtain a single-source precursor solution. S2. Slurry preparation: Outer slurry: Weigh 20g each of HfC, ZrC, TaC, NbC and TiC powder (D50=1μm), mix to obtain 100g of carbide mixed powder; add 5.2g of short-cut SiC fibers (average length 200μm, average diameter 10μm), 40g of single-source precursor solution, 5g of dibutyl phthalate and 2g of herring oil; The above raw materials were placed in a ball mill jar and ball milled in air for 40 hours using zirconia balls (ball-to-material ratio 3:1) to obtain an outer slurry with a viscosity of approximately 6000 cP. Inner layer slurry: Weigh 50g of HfB2 powder (D50=1μm), 39g of ZrB2 powder (D50=1μm), and 8.5g of SiC powder (D50=0.5μm), and mix them; add 35g of the above-mentioned single-source precursor solution, 5g of dibutyl phthalate, and 2g of herring oil. Ball mill at a ball-to-powder ratio of 3:1 for 38h to obtain an inner layer slurry with a viscosity of approximately 5000 cP.

[0023] S3. Construction of layered green blank: The outer and middle layers of slurry are cast into green blank strips with a thickness of 0.5 mm using the casting method. Then, the inner and outer green blank strips are stacked in sequence. The stacked green blank is held under cold isostatic pressing at 150 MPa for 3 minutes to obtain a dense layered green blank. S4. Precursor transformation: The layered green body is heated from room temperature to 600℃ at a heating rate of 1℃ / min under nitrogen atmosphere protection, and then heated from 600℃ to 1200℃ at a heating rate of 3℃ / min, and held for 1h to decompose the polymer precursor into nano-multiphase ceramic. S5. Densification sintering: The preform after precursor conversion is placed in a spark plasma sintering furnace. Under a nitrogen atmosphere, a pressure of 10 MPa is applied, and the temperature is increased to 1400℃ at a rate of 150℃ / min. After reaching this temperature, the pressure is increased to 40 MPa within 2 minutes, and then the temperature is increased to the target sintering temperature of 1950℃ at a rate of 150℃ / min. The temperature is held at this temperature for 15 minutes. Finally, the preform is cooled to room temperature in the furnace to obtain an ultra-high temperature refractory material.

[0024] Example 2 This embodiment provides a method for preparing ultra-high temperature refractory materials. Unlike Example 1, the precursor solution is prepared as follows: 10.0 g of polycarbosilane with a number average molecular weight (Mn) of 1395 is weighed and added to 80 mL of n-hexane. The mixture is stirred at room temperature until completely dissolved. Then, 5.20 g of hafnium tert-butoxide, 4.55 g of zirconium tert-butoxide, 4.36 g of tantalum ethoxide, 3.98 g of niobium ethoxide, and 4.26 g of tetraisopropyl titanate are added sequentially. The reaction system is stirred at 300 rpm for 12 h at room temperature and then cooled to room temperature to obtain a single-source precursor solution.

[0025] Example 3 This embodiment provides a method for preparing ultra-high temperature refractory materials. Unlike Example 1, the precursor solution is prepared as follows: 30.0 g of polycarbosilane with a number average molecular weight (Mn) of 1395 is weighed and added to 120 mL of tetrahydrofuran. The mixture is stirred at room temperature until completely dissolved. Then, 2.01 g of hafnium neodecanoate, 1.81 g of zirconium neodecanoate, 2.15 g of tantalum neodecanoate, 1.95 g of niobium neodecanoate, and 1.55 g of titanium neodecanoate are added sequentially. The reaction system is stirred at 300 rpm for 4 h at 50 °C and cooled to room temperature to obtain a single-source precursor solution.

[0026] Comparative Example 1 Based on Example 1, the following adjustments were made. Unlike Example 1, in Comparative Example 1, the addition of hafnium acetylacetonate (Hf) was omitted in the preparation of the precursor solution (S1).

[0027] Comparative Example 2 Based on Example 1, the following adjustment was made. Unlike Example 1, in Comparative Example 2, the chopped SiC fibers in the outer layer slurry were changed from 5.2g to 0g in the slurry preparation (S2), that is, no fibers were added.

[0028] Comparative Example 3 Based on Example 1, the single-source precursor solution in the outer layer slurry of Comparative Example 3 was changed from 40g to 20g in Example 1.

[0029] Comparative Example 4 Based on Example 1, the following adjustment was made: In Comparative Example 4, 20g of HfC powder was replaced with an equal amount of ZrC powder in the slurry preparation (S2).

[0030] Comparative Example 5 Based on Example 1, the following adjustment was made. Unlike Example 1, in Comparative Example 5, 39g of ZrB2 powder was replaced with an equal amount of HfB2 powder in the slurry preparation (S2) (i.e., the inner layer became 89g HfB2 + 8.5g SiC).

[0031] Comparative Example 6 Based on Example 1, the adjustment was made. Unlike Example 1, in Comparative Example 6, the heating program in the precursor conversion (S4) was changed to directly heat from room temperature to 1200°C at 5°C / min and hold for 1 hour.

[0032] Experimental Example: The ultra-high temperature refractory materials prepared in Examples 1-3 and Comparative Examples 1-6 were tested as follows: Room temperature flexural strength: Tested according to ASTM C1161-18 standard. Samples were processed into strip specimens with dimensions of 3mm × 4mm × 50mm (height × width × length). A universal testing machine was used with a span of 40mm and a loading speed of 0.5mm / min. The maximum load (F) at fracture was recorded, and the flexural strength (σ) was calculated: σ = 3FL / (2bh) 2 Where L is the span (40mm), b is the sample width (4mm), and h is the sample height (3mm). Fracture toughness: Tested according to ASTM C1421-18 standard; the sample was processed into a strip specimen with dimensions of 3mm × 6mm × 50mm (height × width × length). A notch was cut in the middle of the specimen with a diamond saw blade. The depth of the notch was half the height of the specimen (about 3mm) and the width of the notch was 0.2mm. A three-point bending test was performed with a span of 40mm and a loading speed of 0.05mm / min; the fracture load was recorded and the fracture toughness was calculated. High-temperature bending strength: The sample was processed into a strip specimen with dimensions of 3mm×4mm×50mm. Using a high-temperature universal testing machine, it was heated to 2800℃ and held for 10min under nitrogen atmosphere protection. A three-point bending test was performed with a span of 40mm and a loading speed of 0.5mm / min. The fracture load was recorded and the high-temperature bending strength was calculated. Vickers hardness: Tested according to ASTM C1327-15 standard; The results are shown in Table 1 below: Table 1

[0033] In summary, the ultra-high temperature refractory materials prepared in Examples 1-3 exhibit excellent comprehensive properties, including high room temperature flexural strength, high fracture toughness, excellent high temperature flexural strength, and Vickers hardness. This is attributed to the complete formulation design, such as the synergistic effect of multiple carbides / borides, the toughening effect of SiC fibers, the nano-multiphase ceramics provided by the precursor solution, and optimized process parameters, such as slow precursor conversion heating and high-pressure sintering.

[0034] In Comparative Example 1, omitting the addition of hafnium acetylacetone (Hf) in the precursor solution resulted in a 24.5% decrease in room temperature flexural strength, a 35.5% decrease in fracture toughness, a 34.2% decrease in high-temperature flexural strength, and a 10% decrease in Vickers hardness. This indicates that Hf plays a crucial role in enhancing the high-temperature performance and hardness of materials, as HfC and HfB2 possess high melting points and excellent thermal stability.

[0035] Comparative Example 2, which did not add chopped SiC fibers to the outer slurry, resulted in a significant 50% reduction in fracture toughness, and a 10% and 14% reduction in room temperature flexural strength and high temperature flexural strength, respectively. This confirms the toughening effect of SiC fibers, which effectively inhibit crack propagation and improve material toughness through bridging and pull-out mechanisms.

[0036] Comparative Example 3 showed that reducing the amount of single-source precursor solution in the outer slurry resulted in a 30% decrease in room temperature flexural strength, a 30% decrease in fracture toughness, a 47.4% decrease in high-temperature flexural strength, and a 20% decrease in Vickers hardness. This indicates that the precursor solution, as a binder and nanophase source, has a significant impact on slurry formation, pyrolysis densification, and final properties; reducing its amount may lead to increased porosity and decreased bonding strength.

[0037] Comparative Example 4, which replaced the HfC powder in the outer slurry with an equal amount of ZrC powder, resulted in a 20% decrease in high-temperature flexural strength and a slight decrease in other properties (a 4% decrease in room-temperature flexural strength, a 4% decrease in fracture toughness, and a 5% decrease in Vickers hardness). This indicates that HfC has superior performance at high temperatures, and its higher melting point and oxidation resistance help maintain high-temperature strength.

[0038] Comparative Example 5, which replaced the ZrB2 powder in the inner slurry with an equal amount of HfB2 powder, resulted in a 10% decrease in fracture toughness, a 6% decrease in room temperature flexural strength, and a 9% decrease in high temperature flexural strength, but a slight increase in Vickers hardness. This suggests that ZrB2 may have better sinterability and toughness, and that using HfB2 exclusively may increase brittleness, leading to a decrease in overall performance despite the increased hardness.

[0039] Comparative Example 6 employed rapid heating during the precursor conversion process (directly increasing the temperature from room temperature to 1200°C at a rate of 5°C / min), resulting in a 40% decrease in room temperature flexural strength, a 36% decrease in fracture toughness, a 52.6% decrease in high-temperature flexural strength, and a 25% decrease in Vickers hardness. This highlights the importance of slow heating (such as the stepped heating in Example 1) for the uniform pyrolysis of the precursor; rapid heating easily induces cracks and porosity, reducing densification and mechanical properties.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An ultra-high-temperature refractory material, characterized in that, The superhigh-temperature refractory material comprises an ablation-resistant outer layer and an oxidation-resistant inner layer; the ablation-resistant outer layer is composed of a composite material containing a carbide ceramic matrix and first reinforcing fibers; the carbide ceramic matrix is composed of a solid solution formed by equimass HfC, ZrC, TaC, NbC and TiC; and the first reinforcing fibers are short-cut SiC fibers.

2. An ultra-high-temperature refractory material according to claim 1, characterized in that, The oxidation-resistant inner layer is composed of HfB2, ZrB2 and SiC, and the weight ratio of HfB2, ZrB2 and SiC is 10-80:10-80:10-30.

3. The ultra-high-temperature refractory material of claim 1, wherein, The mass fraction of the first reinforcing fibers is 1%-10% of the total mass of the ablation-resistant outer layer.

4. A method for producing an ultra-high-temperature refractory material according to any one of claims 1 to 3, characterized in that The method comprises the following steps: S1. Preparation of a precursor solution: an oxygen-free silicon-based polymer precursor and metal organic compounds containing Hf, Zr, Ta, Nb and Ti are dissolved in an organic solvent to form a single-source precursor solution; S2. Preparation of a slurry: the single-source precursor solution is mixed with ceramic powders and reinforcing fibers of the corresponding layer respectively, and ball milling is performed to prepare an inner layer slurry and an outer layer slurry; S3. Construction of a layered green body: the slurry of each layer is respectively formed into a green tape by a tape casting method, and then the green tapes are stacked in the order of the inner layer and the outer layer, and cold isostatic pressing is performed to obtain a layered green body; S4. Precursor conversion: the layered green body is heated to 1000-1400℃ at a heating rate of 1-10℃ / min under the protection of an inert atmosphere, and is kept at the temperature for 0.5-2h, so that the polymer precursor is cracked and converted into a nano-composite ceramic; S5. Densification sintering: the green body after the precursor conversion is placed in a spark plasma sintering furnace for spark plasma sintering, and is cooled in the furnace, to obtain the superhigh-temperature refractory material.

5. A method of producing an ultra-high-temperature refractory material according to claim 4, characterized in that, The oxygen-free silicon-based polymer precursor comprises one or both of vinyl polycarbosilane and polycarbosilane, and the number average molecular weight is 800-2000; the metal organic compound comprises one or more of acetylacetone, alcoholate or carboxylate of each metal; and the organic solvent comprises one or more of dimethylbenzene, n-hexane and tetrahydrofuran.

6. A method of producing an ultra-high-temperature refractory material according to claim 4, characterized in that, In the ball milling process of the slurry, zirconium oxide balls are used, the ball-to-material ratio is 2-5:1, and the ball milling time is 36-48h.

7. A method of producing an ultra-high-temperature refractory material according to claim 4, characterized in that, In step S3, the thickness of the green tape is 0.1-2 mm; and the pressure of the cold isostatic pressing is 100-200 MPa, and the pressure keeping time is 1-5 min.

8. A method of producing an ultra-high-temperature refractory material according to claim 4, characterized in that, In step S4, the inert atmosphere is one of high-purity argon and nitrogen.

9. The method of claim 4, wherein the ultra-high-temperature refractory material is prepared by the steps of: mixing the first and second powders to form a mixture; and sintering the mixture to form the ultra-high-temperature refractory material. The precursor conversion comprises the following steps: heating from room temperature to 600℃ at a heating rate of 1℃ / min, and heating from 600℃ to 1200℃ at a heating rate of 3℃ / min, and keeping at the temperature for 1h.

10. The method of claim 4, wherein the ultra-high-temperature refractory material is prepared by the steps of: mixing the first and second powders to form a mixture; and sintering the mixture to form the ultra-high-temperature refractory material. The plasma sintering comprises the following steps: heating to 1400℃ at a heating rate of 150℃ / min under a nitrogen atmosphere and at a pressure of 10-12 MPa; after reaching 1400℃, the pressure is increased to 30-50 MPa within 1-3 min, and then heating to 1900-2100℃ at a heating rate of 100-200℃ / min, and keeping at the temperature for 10-20 min.

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