A high-entropy carbide ceramic (TiZrNbTaW)C with fine-grained structure, its preparation method and application

Abstract

This invention discloses a (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure, its preparation method, and its applications, belonging to the field of high-entropy ceramic technology. This invention calculates the material ratio using a carbothermal reduction equation. The raw materials for the high-entropy carbide ceramic include oxides weighed according to stoichiometric ratios and 0.6~0.7 times the corresponding mass of carbon powder. Therefore, this invention provides a fine-grained, high-hardness, and high-toughness (TiZrNbTaW)C high-entropy carbide ceramic with a hardness (HV0.5) of 15~25, preferably 18~22, and a fracture toughness of 2~5 MPa·m. 1 / 2 The relative density is ≥98%.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy ceramics technology, specifically relating to a (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] High-entropy carbide ceramics are single-phase solid solution ceramic materials composed of four or more refractory transition metal carbides. Due to the characteristics of the carbide material composition and the influence of the high-entropy effect, high-entropy carbide ceramic materials have excellent properties such as high hardness, high wear resistance, corrosion resistance, and oxidation resistance. Therefore, they are widely used in defense, aerospace, high-speed cutting and other fields.

[0004] Currently, common high-entropy carbide compositions are mainly transition metal carbides. While the pure ceramic phase brings the aforementioned excellent properties, it also results in high brittleness and low toughness. In recent years, researchers have attempted to introduce a second phase into high-entropy carbide ceramics to address the problem of low toughness. Existing technologies have disclosed the introduction of a metallic binder phase, Co, to improve the fracture toughness of ceramics, achieving a maximum toughness of 10.9 MPa. m 1 / 2 However, this method inevitably reduces the material's hardness to 1647 HV1, and because metals soften at high temperatures, it also reduces the material's high-temperature performance. Existing technology also discloses introducing SiC whiskers into (TiZrHfNbTa)C to improve fracture toughness, but the introduction of 20 vol% SiC whiskers only increases the ceramic toughness from 3.0 MPa. m 1 / 2 Increased to 4.3 MPa m 1 / 2 Furthermore, the introduction of whiskers can also lead to other problems such as difficulty in dispersion and increased costs.

[0005] Currently, high-entropy ceramics prepared using the carbothermal reduction method still face the problem of rapid grain growth. Using powders with an initial particle size of less than 1 micrometer, the particle size generally exceeds 10 micrometers after sintering. The transgranular fracture caused by this large grain size is the main reason for the low fracture toughness of high-entropy ceramics. Therefore, there is an urgent need to design high-entropy carbide ceramic materials with fine-grained structures to improve the fracture toughness of high-entropy ceramics and broaden their application range. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure, its preparation method, and its applications. This invention provides a method for adding W element, utilizing the carbon-depleted W to induce precipitation and dispersed distribution, resulting in grain boundary pinning. This effectively suppresses grain growth in the high-entropy carbide ceramic. The fine-grained structure and the synergistic effect of W metal improve the fracture toughness of the high-entropy carbide ceramic, enhancing the material's reliability.

[0007] This invention provides a method for preparing fine-grained, high-hardness, and high-toughness (TiZrNbTaW)C high-entropy carbide ceramics. The mass of the main components is calculated according to the carbothermic reduction equation, as shown below:

[0008]

[0009] By controlling x between 0.6 and 0.7, the quality of the toner can be determined.

[0010] The preparation method of fine-grained high-entropy carbide ceramics includes: (1) weighing and wet-milling TiO2 powder, ZrO2 powder, Nb2O5 powder, Ta2O5 powder, WO3 powder, and C powder according to the specified ratio. (2) pressing and molding the mixed material from step (1) and performing a vacuum carbothermal reduction reaction, crushing it to obtain fine-grained high-entropy carbide ceramic powder, and finally sintering it using SPS to obtain fine-grained high-entropy carbide ceramic bulk material.

[0011] This invention introduces non-FCC structurally stable WC into the high-entropy carbide ceramic composition and induces W element precipitation through a low-carbon method. The fine and uniformly dispersed W metal particles can significantly inhibit the grain growth of high-entropy carbide ceramics. Compared with ordinary high-entropy carbide ceramics, the grain size is reduced by an order of magnitude while exhibiting higher fracture toughness.

[0012] Currently, for carbon-deficient high-entropy carbide systems, only W has been found to precipitate in the form of fine particles under carbon-deficient conditions. Other elements that can precipitate metal or ceramic second phases include Cr and Mo, but no reports have mentioned other metals or metal carbides that can inhibit grain growth.

[0013] Experimental results show that the sample with a carbon stoichiometry of 0.7 exhibited a large number of uniformly dispersed W metal particles, accompanied by a significant refinement of grain size. Therefore, the dispersed distribution of W metal is related to grain refinement. As a second phase, the uniform distribution and fine particle size of W metal meet the conditions for the Zener pinning effect to inhibit grain growth. Therefore, it is determined that W metal particles hinder the grain growth of the ceramic. Replacing W with other metallic elements, such as Mo, Cr, or V, does not achieve the same effect.

[0014] To achieve the above objectives, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure. The raw materials include TiO2 powder, ZrO2 powder, Nb2O5 powder, Ta2O5 powder, WO3 powder, and carbon powder. According to the molar ratio, TiO2:ZrO2:Nb2O5:Ta2O5:WO3=(0.9~1.1):(0.9~1.1):(0.5~0.6):(0.5~0.6):(0.9~1.1), C:TiO2=(12+5x):1, where 0.6≤x≤0.7.

[0015] Preferably, TiO2:ZrO2:Nb2O5:Ta2O5:WO3=1:1:1 / 2:1 / 2:1, C:TiO2=(12+5x):1, 0.6≤x≤0.7.

[0016] In this invention, strict control of the carbon stoichiometry is required to obtain a fine-grained, high-entropy carbide ceramic bulk material that exhibits both reduced grain size and higher fracture toughness. For example, when x is 0.5, insufficient ZrO2 reduction may occur; while when x is 0.8 or 0.9, the average grain size is greater than 5 micrometers, and it is impossible to simultaneously achieve high fracture toughness and high hardness.

[0017] The material proportions are calculated using the carbothermic reduction equation. The raw materials for the high-entropy carbide ceramic include oxides weighed according to stoichiometric ratios and carbon powder with a mass of 0.6 to 0.7.

[0018] The (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure prepared by this invention has a hardness (HV0.5) of 15-25, preferably 18-22, and a fracture toughness of 2-5 MPa·m. 1 / 2 Preferably, it is 3.5~4.5 MPa·m 1 / 2 The relative density is ≥98%. In addition, the grain size of the (TiZrNbTaW)C high-entropy carbide ceramic prepared by the preparation method of the present invention is less than 5 micrometers, and can be 1~5 micrometers, with an average grain size of 1.5~2.5 micrometers.

[0019] Secondly, the present invention provides a method for preparing the above-mentioned (TiZrNbTaW)C high-entropy carbide ceramic with fine-grained structure, comprising the following steps: Step 1: Ball milling and mixing: Add solvent to TiO2 powder, ZrO2 powder, Nb2O5 powder, Ta2O5 powder, WO3 powder and carbon powder, then ball mill. After ball milling, dry to obtain the first product. Step 2, Powder Molding: The first product is shaped to obtain the second product; Step 3, carbothermic reduction reaction: The second product is heated in a vacuum atmosphere, kept at that temperature, and then cooled to room temperature to obtain the third product; Step 4: Crushing and grinding: The third product is crushed and ground to obtain the fourth product; Step 5, Sintering: The fourth product is sintered under a protective atmosphere using a spark plasma sintering process, and then cooled to obtain a high-entropy carbide ceramic product.

[0020] In one or more embodiments, in step one, the ball-to-material mass ratio in the ball mill is (4~6):1; the ball milling speed is 200~300 r / min; the ball milling time is 8~12 h; and the solvent includes alcohol. The amount of solvent added is 0.5~2 mL / g, preferably 0.5~1 mL / g, and most preferably 0.7 mL / g.

[0021] In one or more embodiments, in step two, the molding pressure is 200~300 MPa and the molding time is 1~10 min.

[0022] In one or more embodiments, in step three, the conditions for the carbothermic reduction reaction are: reaction temperature of 1850~1950 ℃, heating rate of 10~20 ℃ / min, and holding time of 1~5 h.

[0023] Furthermore, the specific temperature of the carbothermic reduction reaction can be 1850 ℃, 1860 ℃, 1870 ℃, 1880 ℃, 1890 ℃, 1895 ℃, 1900 ℃, 1905 ℃, 1910 ℃, 1915 ℃, 1920 ℃, 1930 ℃, 1940 ℃, 1950 ℃, etc., preferably 1890~1910 ℃, and most preferably 1900 ℃.

[0024] Furthermore, the heat preservation time can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 hours, preferably 1 to 2 hours.

[0025] Experiments revealed that 1900 °C was the optimal temperature. Previous attempts at temperatures below 1800 °C resulted in ZrO2 residue. This is likely because the reduction reaction of the intermediate product WC to ZrO2 cannot be initiated at lower temperatures. Under a CO partial pressure of 10 Pa, WC and ZrO2 require a temperature of 1400 °C to meet thermodynamic conditions for the reaction to occur. However, this high-temperature reaction may have even higher kinetic requirements, necessitating even higher temperatures to accelerate the reaction. Figure 5As shown. However, if the temperature is too high, such as 2000 ℃ or above, spontaneous densification of the material will occur due to the increased temperature (this is because the temperature rise approaches the eutectic point temperature of W and C by 0.8 times, leading to significant densification, but not complete densification). The particles will agglomerate significantly, making subsequent crushing difficult and preventing sintering. Even if crushing occurs, the particle size of the broken powder will be uneven, resulting in low density of the material after further sintering. Figure 6 As shown.

[0026] In one or more embodiments, in step four, the present invention does not specifically limit the crushing and grinding method; any crushing method such as a mortar and pestle, ball mill, or crusher can be used, as long as impurities are not introduced. In this embodiment, a mortar and pestle grinding method is used. Using the preparation method of the present invention, the product after carbothermic reduction can be directly manually ground using a mortar and pestle.

[0027] The powder cake after carbothermic reduction exhibits obvious soft agglomeration, requiring appropriate grinding and crushing methods; otherwise, loose powder cannot be obtained for sintering. It is sufficient to crush the powder to the point where no obvious particle agglomeration is visible to the naked eye.

[0028] In one or more embodiments, the specific conditions for the spark plasma sintering process in step five are: a heating rate of 50~150 ℃ / min, a sintering temperature of 1800~2200 ℃, a holding time of 5~20 min, and a pressure of 30~50 MPa maintained during the heating and holding processes. The protective gas includes argon.

[0029] Furthermore, the heating rate can be 50 ℃ / min, 60 ℃ / min, 70 ℃ / min, 80 ℃ / min, 90 ℃ / min, 100 ℃ / min, 110 ℃ / min, 120 ℃ / min, 130 ℃ / min, 140 ℃ / min, or 150 ℃ / min, preferably 90~110 ℃ / min.

[0030] The sintering temperature can be 1800 ℃, 1850 ℃, 1900 ℃, 1950 ℃, 2000 ℃, 2050 ℃, 2100 ℃, 2150 ℃, 2200 ℃, etc., preferably 1900~2100 ℃.

[0031] The specific heat preservation time can be 5 min, 10 min, 15 min, 20 min, etc., with 5 to 10 min being preferred.

[0032] Preferably, the heating and pressurization method includes: heating to 2000-2100℃ at a rate of 50-150℃ / min, holding at that temperature for 5-15 minutes, and then cooling to room temperature with the furnace. Preferably, the preparation method includes the following steps in sequence: (1) Powder weighing: According to the molar percentage, TiO2:ZrO2:Nb2O5:Ta2O5:WO3=1:1:1 / 2:1 / 2:1, C:TiO2=(12+5x):1, (0.6≤x≤0.7), weigh the corresponding mass of powder according to the above molar ratio; (2) Ball milling: Place the powder in a ball milling jar, add anhydrous ethanol at 0.7 mL / g, and use ZrO2 grinding beads for ball milling. The mass ratio of ball to powder is (4~5):1. The ball milling speed is 250~350 rpm, and the ball milling time is 5~10 h. After the ball milling is completed, place it in a drying oven and dry it to obtain a uniformly mixed oxide powder. (3) Place the oxide powder in a cold press mold and use a pressure of 200~300 MPa for a holding time of 1~5 min to form the powder; (4) Place the shaped powder in a graphite crucible and heat it to 1900 ℃~1950 ℃ at 10~20℃ / min under a vacuum atmosphere (vacuum degree <10 Pa). After holding the temperature for 1~2 h, cool it to room temperature with the furnace to obtain a high entropy carbide powder cake. (5) High entropy carbide powder is obtained by crushing and grinding the high entropy carbide powder using an agate mortar; (6) The high-entropy carbide powder was placed in a graphite mold and the sample was sintered by pressure heating in a spark plasma sintering furnace. During the heating and holding process, the pressure was maintained at 30~50 MPa. The temperature was increased to 2000~2100 ℃ at 50~150 ℃ / min. After holding for 5~15 min, the sample was cooled to room temperature in the furnace to obtain the high-entropy carbide ceramic bulk material.

[0033] Thirdly, this invention provides the application of the above-mentioned (TiZrNbTaW)C high-entropy carbide ceramics with fine grain structure in national defense, aerospace, and high-speed cutting.

[0034] One or more of the above technical solutions have the following advantages or beneficial effects: (1) In the high-entropy carbide ceramic composition, the present invention introduces W element, which is not stable in the carbide non-FCC structure. Through carbon depletion treatment, W metal is induced to precipitate uniformly and dispersedly, which plays a role in inhibiting grain growth and refining grain size. It can effectively weaken transgranular fracture during crack propagation and improve the fracture toughness of the material.

[0035] (2) In the process of synthesizing high-entropy carbide ceramic powder, the present invention uses carbothermal reduction as the powder synthesis process. Compared with the liquid phase method, the process is simple, low-cost, highly repeatable, and the synthesis process does not produce corrosive gases. It has low requirements for equipment and is suitable for large-scale industrial production.

[0036] (3) In the formulation of high-entropy carbide ceramic powder, the present invention introduces carbon powder with a low stoichiometric ratio. At the same time, due to the low carbon content caused by the carbon-depleted treatment, there is no residual graphite in the powder after synthesis, and only simple crushing and grinding is required to obtain high-purity high-entropy carbide ceramic powder.

[0037] (5) In the preparation method of the present invention, the carbothermic reduction reaction temperature is 1850~1950 ℃ (preferably 1900 ℃) to prepare fine-grained high-purity high-entropy carbide ceramics. If the temperature is too low, it will lead to the problem of ZrO2 residue. If the temperature is too high, the particles will agglomerate significantly, which will increase the difficulty of crushing. The particle size of the crushed powder will also be uneven, and the density of the sintered material will be low. Attached Figure Description

[0038] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0039] Figure 1 These are backscattered electron images of materials prepared with different carbon stoichiometry ratios; where (a) represents a carbon stoichiometry ratio of 0.6, (b) represents a carbon stoichiometry ratio of 0.7, (c) represents a carbon stoichiometry ratio of 0.8, and (d) represents a carbon stoichiometry ratio of 0.9. Figure 2 These are backscattered electron diffraction pole figures of materials prepared with different carbon stoichiometry; where (a) represents a carbon stoichiometry of 0.6, (b) represents a carbon stoichiometry of 0.7, (c) represents a carbon stoichiometry of 0.8, and (d) represents a carbon stoichiometry of 0.9. Figure 3 These are the mechanical properties of materials prepared with different carbon stoichiometric ratios; Figure 4 Statistical distribution of grain size of materials prepared with different carbon stoichiometry; where (a) is carbon stoichiometry of 0.6, (b) is carbon stoichiometry of 0.7, (c) is carbon stoichiometry of 0.8, and (d) is carbon stoichiometry of 0.9. Figure 5 The figure shows the relationship between the Gibbs free energy of the reaction between some transition metal carbides and ZrO2 and temperature, with the partial pressure of CO being 10 Pa. Figure 6A comparison of the morphology of powders obtained by carbothermal reduction at different temperatures; (a) powder synthesized at 1900℃ (grinding and crushing); (b) powder synthesized at 2200℃ (crushed by a vibratory crusher). Figure 7 Backscattered electron image of a polished sample at 1600℃ during carbothermal reduction; Figure 8 (TiZrNbTaMo)C was prepared by replacing W with Mo. 0.7 The backscattered electron diagram. Detailed Implementation

[0040] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0041] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0042] Example 1 This invention provides a (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure. The nominal carbon stoichiometry of this ceramic is 0.7, and the material name can be written as (TiZrNbTaW)C. 0.7 This can be abbreviated as C7. After calculating the mass of each oxide and carbon powder according to the carbothermic reduction equation, the powder was weighed. The weighed powder was ball-milled using anhydrous ethanol as the grinding medium, with 0.7 mL / g of anhydrous ethanol added. ZrO2 grinding beads and powder were added at a ball-to-powder ratio of 5:1, and ball-milled at 250 rpm for 8 h. After removal, it was dried in a drying oven at 70℃ for 24 h to obtain a uniformly mixed oxide powder. 10 g of the oxide powder was weighed and placed into a 28 mm diameter cold-press mold, and pressed at 200 MPa for 2 min. The pressed powder cake was placed in a graphite crucible and placed in a reactor for carbothermic reduction reaction. Under a vacuum atmosphere (vacuum degree <10 Pa), the temperature was increased to 1900℃ at 10 ℃ / min, held for 1 h, and then cooled to room temperature with the furnace to obtain a high-entropy carbide powder cake. After crushing and grinding the high-entropy carbide powder using an agate mortar, the resulting powder was placed in a 20 mm graphite mold. The powder was sintered in an SPS sintering furnace. During heating and holding, the pressure was maintained at 40 MPa, and the temperature was increased to 2000 °C at a rate of 100 °C / min, held for 5 min, and then cooled to room temperature in the furnace to obtain a high-entropy carbide ceramic material with a fine-grained structure. The backscattered electron pattern of this ceramic material is shown below. Figure 1 As shown in (b), the backscattered electron diffraction pole figure is as follows: Figure 2 As shown in (b).

[0043] Example 2 Unlike Example 1, this invention provides a (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure. The nominal carbon stoichiometry of this ceramic is 0.6, and the material name can be written as (TiZrNbTaW)C. 0.6 It can be abbreviated as C6. The rest of the preparation method is the same as in Example 1.

[0044] The backscattered electron pattern of this ceramic material is as follows: Figure 1 As shown in (a), the backscattered electron diffraction pole figure is as follows: Figure 2 As shown in (a).

[0045] Comparative Example 1 A high-entropy carbide ceramic of (TiZrNbTaW)C with normal grain size and a nominal carbon stoichiometry of 0.8 can be named (TiZrNbTaW)C. 0.8 This can be abbreviated as C8. After calculating the mass of each oxide and carbon powder according to the carbothermic reduction equation, the powder was weighed. The weighed powder was ball-milled using anhydrous ethanol as the grinding medium, with ZrO2 grinding beads and powder added at a ball-to-powder ratio of 5:1. The mixture was ball-milled at 250 rpm for 8 hours, then dried in a drying oven at 70℃ for 24 hours to obtain a uniformly mixed oxide powder. 10 g of the oxide powder was weighed and placed into a 28 mm diameter cold-press mold, and pressed at 200 MPa for 2 minutes. The pressed powder cake was placed in a graphite crucible and placed in a reactor for carbothermic reduction reaction. Under a vacuum atmosphere (vacuum degree <10 Pa), the temperature was increased to 1900℃ at 10℃ / min, held for 1 hour, and then cooled to room temperature with the furnace to obtain a high-entropy carbide powder cake. The high-entropy carbide powder cake was crushed and ground using an agate mortar, and the resulting powder was placed in a 20 mm graphite mold. The powder was sintered using an SPS sintering furnace. During the heating and holding process, the pressure was maintained at 40 MPa. The temperature was increased to 2000 °C at a rate of 100 °C / min, held for 5 min, and then cooled to room temperature in the furnace to obtain a high-entropy carbide ceramic material with a fine-grained structure. The backscattered electron pattern of this ceramic material is shown below. Figure 1 As shown in (c), the backscattered electron diffraction pole figure is as follows: Figure 2 As shown in (c).

[0046] Comparative Example 2 A high-entropy carbide ceramic of (TiZrNbTaW)C with normal grain size and a nominal carbon stoichiometry of 0.9 can be named (TiZrNbTaW)C. 0.9This can be abbreviated as C9. After calculating the mass of each oxide and carbon powder according to the carbothermic reduction equation, the powder was weighed. The weighed powder was ball-milled using anhydrous ethanol as the grinding medium, with ZrO2 grinding beads and powder added at a ball-to-powder ratio of 5:1. The mixture was ball-milled at 250 rpm for 8 hours, then dried in a drying oven at 70℃ for 24 hours to obtain a uniformly mixed oxide powder. 10 g of the oxide powder was weighed and placed into a 28 mm diameter cold-press mold, and pressed at 200 MPa for 2 minutes. The pressed powder cake was placed in a graphite crucible and placed in a reactor for carbothermic reduction. Under a vacuum atmosphere (vacuum degree <10 Pa), the temperature was increased to 1900℃ at 10℃ / min, held for 1 hour, and then cooled to room temperature with the furnace to obtain a high-entropy carbide powder cake. The high-entropy carbide powder cake was crushed and ground using an agate mortar, and the resulting powder was placed in a 20 mm graphite mold. The powder was sintered using an SPS sintering furnace. During the heating and holding process, the pressure was maintained at 40 MPa. The temperature was increased to 2000 °C at a rate of 100 °C / min, held for 5 min, and then cooled to room temperature in the furnace to obtain a high-entropy carbide ceramic material with a fine-grained structure. The backscattered electron pattern of this ceramic material is shown below. Figure 1 As shown in (d), the backscattered electron diffraction pole figure is as follows: Figure 2 As shown in (d).

[0047] Comparative Example 3 The difference from Example 1 is that the carbothermic reduction temperature was changed from 1900°C to 1600°C, while the rest remained the same.

[0048] like Figure 7 As shown, the backscattered electron image of the polished sample at a carbothermal reduction of 1600℃ shows that the black speckled areas are the unreduced zirconium oxide phase.

[0049] Comparative Example 4 Unlike Example 1, W metal was replaced with Mo to prepare (TiZrNbTaMo)C 0.7 .Depend on Figure 8 The backscattered electron diagram shows no grain refinement.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure, characterized in that, The raw materials include TiO2 powder, ZrO2 powder, Nb2O5 powder, Ta2O5 powder, WO3 powder, and carbon powder. According to the molar ratio, TiO2:ZrO2:Nb2O5:Ta2O5:WO3=(0.9~1.1):(0.9~1.1):(0.5~0.6):(0.5~0.6):(0.9~1.1), C:TiO2=(12+5x):1, where 0.6≤x≤0.

7.

2. The (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure according to claim 1, characterized in that, TiO2:ZrO2:Nb2O5:Ta2O5:WO3=1:1:1 / 2:1 / 2:1, C:TiO2=(12+5x):1, where 0.6≤x≤0.

7.

3. The (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure according to claim 1, characterized in that, The (TiZrNbTaW)C high-entropy carbide ceramic has a hardness of 15~25 HV0.5 and a fracture toughness of 2~5 MPa·m. 1 / 2 Preferably, it is 3.5~4.5 MPa·m 1 / 2 The relative density is ≥98%; The average grain size of the (TiZrNbTaW)C high-entropy carbide ceramic is less than 5 micrometers, preferably 1.5 to 2.5 micrometers.

4. A method for preparing a (TiZrNbTaW)C high-entropy carbide ceramic with a fine-grained structure as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Step 1: Ball milling and mixing: Add solvent to TiO2 powder, ZrO2 powder, Nb2O5 powder, Ta2O5 powder, WO3 powder and carbon powder, then ball mill. After ball milling, dry to obtain the first product. Step 2, Powder Molding: The first product is shaped to obtain the second product; Step 3, carbothermic reduction reaction: The second product is heated in a vacuum atmosphere, kept at that temperature, and then cooled to room temperature to obtain the third product; Step 4: Crushing and grinding: The third product is crushed and ground to obtain the fourth product; Step 5, Sintering: The fourth product is sintered under a protective atmosphere using a spark plasma sintering process, and then cooled to obtain a high-entropy carbide ceramic product.

5. The preparation method according to claim 4, characterized in that, In step one, the ball-to-material mass ratio in the ball mill is (4~6):1; the rotation speed of the ball mill is 200~300 r / min; and the ball milling time is 8~12 h.

6. The preparation method according to claim 4, characterized in that, In step one, the solvent includes alcohol, and the amount of solvent added is 0.5~2 mL / g.

7. The preparation method according to claim 4, characterized in that, In step two, the molding pressure is 200~300MPa, and the molding time is 1~10 min.

8. The preparation method according to claim 4, characterized in that, In step three, the conditions for the carbothermic reduction reaction are: reaction temperature of 1850~1950 ℃, heating rate of 10~20 ℃ / min, and holding time of 1~5 h; preferably, the reaction temperature is 1890~1910 ℃ and the holding time is 1~2 h.

9. The preparation method according to claim 4, characterized in that, In step five, the specific conditions for the spark plasma sintering process are as follows: heating rate of 50~150 ℃ / min, sintering temperature of 1800~2200 ℃, holding time of 5~20 min, and maintaining a pressure of 30~50 MPa during heating and holding; preferably, the sintering temperature is 1900~2100 ℃.

10. The application of a (TiZrNbTaW)C high-entropy carbide ceramic with fine-grained structure as described in any one of claims 1 to 3, or a (TiZrNbTaW)C high-entropy carbide ceramic with fine-grained structure prepared by the preparation method described in any one of claims 4 to 9, in national defense, aerospace, and high-speed cutting.

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