Anisometric high-entropy carbide ceramic material and method of making same

Abstract

This invention relates to a non-uniform high-entropy carbide ceramic material and its preparation method, characterized by its molecular formula Mo. 1‑x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1), where Mo is the key element for composition and performance adjustment; the preparation method uses Mo2C powder, TiC powder, ZrC powder, NbC powder, TaC powder and graphite as raw materials, adds stearic acid as ball milling media, and grinds in a WC ball mill jar to obtain mixed powder; then the mixed powder is pressed into shape and hot-pressed and sintered; after sintering, it is cooled to obtain the target product. This invention successfully synthesized a series of high-entropy carbide ceramics with different Mo contents by adjusting the Mo content and preparation process. Testing showed that the mechanical properties, oxidation resistance, and high-temperature tribological properties of this series of high-entropy ceramics all showed a regular change with increasing Mo content, and the oxides generated by Mo at high temperature had a synergistic lubricating effect, reducing the friction coefficient and thus improving the tribological properties of high-entropy carbides. This not only expands the high-entropy carbide system but also gives it potential application prospects in extreme and harsh working conditions such as high temperature and high load.

Description

Technical Field

[0001] This invention relates to a method for preparing non-uniform high-entropy carbides and their bulk ceramics, and more particularly to a cubic rock salt structure high-temperature resistant metal ceramic Mo with different Mo contents. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) and its preparation method are used to improve the tribological properties of high-entropy carbides, expand the high-entropy carbide ceramic system, and thus expand the applications of high-entropy carbides. This belongs to the field of structural ceramics and their high-temperature ceramic material preparation technology. Background Technology

[0002] High-entropy ceramics, as a novel ceramic material developed in recent years, have become a research hotspot due to their large configurational entropy and unique structure and properties. They tend to maintain a single phase even under extreme temperature, pressure, and chemical environments, ensuring stability under various service conditions. Research results have increased dramatically year by year, and the systems involved have expanded from oxide systems to various systems, such as the currently studied boride, carbide, and nitride systems, as well as the gradually developing silicide and sulfide systems. Among them, carbide high-entropy ceramics are favored by researchers for their excellent properties such as high hardness, high strength, high elastic modulus, good thermal stability, and radiation resistance. To maximize configurational entropy, current research focuses on equimolar ratios. However, considering comprehensive properties such as friction, mechanical properties, and oxidation resistance, equimolar ratios do not necessarily offer the optimal overall performance. The literature "Carbon-deficient high-entropy (Zr)" refers to this. 0.17 Nb 0.2 Ta 0.2 Mo 0.2 W 0.2 C 0.89 A potential high temperature and vacuum wear-resistant material[J]. Mater. Des., 2023, 226: 111680.” A Zr material with carbon stoichiometry deviation was prepared. 0.17 Nb 0.2 Ta 0.2 Mo 0.2 W 0.2 C 0.89High-entropy ceramics were found to exhibit significantly improved hardness and fracture toughness compared to their corresponding transition metal carbide ceramics. This suggests that the presence of carbon vacancies is beneficial for enhancing mechanical properties such as hardness, Young's modulus, and flexural strength. The literature "Phase stability and mechanical properties of novelhigh entropy transition metalcarbides[J]. Acta Materialia, 2019, 166: 271-280." found that the hardness and strength of high-entropy carbide ceramics can be adjusted through valence electron concentration, which endows high-entropy ceramics with a certain degree of designability. Another literature, "Lowthermal conductivity of dense (TiZrHfVNbTa)C x The paper "High-entropy carbides by tailoring carbon stoichiometry. J.Adv. Ceram.12.1 (2023)" proposes that the thermophysical properties of high-entropy carbide ceramics can be effectively controlled through multi-element design and non-stoichiometric regulation, achieving precise control of thermal conductivity within different temperature ranges. This provides a framework for the design and optimization of thermal control materials in fields such as thermal protection for hypersonic vehicles and heat dissipation for high-power devices. High-entropy carbides, due to their extremely high melting points (>3000℃), are often used in extreme operating conditions such as high temperatures. Through non-equimolar component design, it is expected that the overall performance of high-entropy carbides can be further improved, showing promising application prospects. Summary of the Invention

[0003] This invention discloses a non-uniform high-entropy ceramic material Mo. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) and its preparation method, by adjusting the content of Mo and the preparation process, a bulk ceramic material with excellent mechanical properties, high temperature oxidation resistance, high temperature resistance and high wear resistance was obtained, which meets the service requirements of mechanical parts under harsh conditions such as high temperature and high load.

[0004] The aforementioned non-uniform high-entropy carbide ceramic is a single-component ceramic, and its molecular formula is Mo. 1-x (Ti 1 / 4 Zr 1 / 4Nb 1 / 4 Ta 1 / 4 ) x C (x ≠0.8, 0< x <1), in which the metallic elements have the characteristics of non-equimolar ratio and adjustable Mo content, the total amount of metallic elements is 1, with Mo playing a role in regulating lubrication performance, and the other four elements maintaining an equal proportion, thus ensuring a high configurational entropy. Simultaneously, since Ti, Zr, Nb, Ta, and Mo have similar crystal structures and chemical properties in carbide form, they can form stable high-entropy solid solution structures. The introduction of multiple elements such as Ti, Zr, Nb, and Ta increases the mixing entropy of the material, making the formation of non-equimolar high-entropy phases possible. The aforementioned series of high-entropy carbide ceramics exhibits the crystallization characteristics of rock salt structure, and its crystal structure schematic diagram and high-resolution transmission microscopy image are shown below. Figure 1 As shown.

[0005] I. To achieve the above-mentioned non-uniform high-entropy carbide ceramics, the present invention adopts the following preparation scheme:

[0006] 1) Weigh Mo2C powder, TiC powder, ZrC powder, NbC powder, TaC powder and graphite according to the above chemical element stoichiometry, add stearic acid accounting for 1%~6% of the total weight of the mixed powder as ball milling media, and grind under an inert atmosphere to obtain mixed powder; the purity of the raw material Mo2C powder, TiC powder, ZrC powder, NbC powder, TaC powder and graphite is ≥99%, and the particle size is 1~3μm;

[0007] Grinding involves placing the raw material in the grinding jar of a ball mill and adding tungsten carbide grinding balls to grind it into a mixed powder. During grinding, the mass ratio of grinding balls to the mixture is 5:1 to 20:1; the speed of the ball mill is 200 to 600 rpm; and the grinding time is 8 to 48 hours.

[0008] The purpose of ball milling is to make the powder and the grinding balls in the jar collide and rub against each other at high speed, so as to achieve the functions of crushing, grinding, mixing and dispersing the sample.

[0009] 2) Press the target mixed powder obtained in step 1) into a green body, then hot press and sinter the green body, and cool it after sintering to obtain the target product Mo. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) Bulk ceramics; vacuum is applied during hot pressing and sintering at a pressure of 1.5~30 MPa, with a vacuum degree <10. -1 Pa, heating rate of 5~10 ℃ / min, sintering temperature of 1700~2000 ℃, sintering time of 1~2 hours.

[0010] The synthesis mechanism of this invention: using transition metal carbide TM (Mo2C, TiC, ZrC, NbC, TaC) powders with different crystal structures and carbon stoichiometry, and graphite as raw materials, based on TM(s) + C(s) → HEC-Mo x (s) The reaction strategy involves in-situ synthesis of a series of uniformly distributed high-entropy carbide ceramic materials using mechanical grinding and hot-pressing sintering techniques with controlled Mo content. The sintering process significantly impacts the structure and properties of the synthesized non-uniform high-entropy carbide ceramics. Too low a sintering temperature results in insufficient densification and failure to synthesize a single phase, while too high a temperature leads to melting and molten metal outflow. Excessive holding time and pressure result in larger grain growth, leading to poor performance. Insufficient ball milling speed and time also cause inadequate powder mixing, resulting in uneven elemental distribution in the synthesized samples and affecting their performance.

[0011] II. Non-uniform high-entropy ceramic material Mo 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x Characterization and performance of <1).

[0012] 1. Structural characterization

[0013] Figure 2 The XRD pattern of the non-uniform high-entropy carbide ceramic material synthesized in this invention is shown below. Figure 2 It can be seen that the prepared Mo 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x The ceramics with x = 0.2, 0.4, and 0.6 are cubic phases with space group Fm⁻³m. The product purity is nearly single-phase, and the diffraction peaks show a regular shift with increasing Mo content. When x = 0.2, 0.4, and 0.6, the cell parameters are as follows: Mo 0.8 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.2 C ( a =4.29286 Å), Mo 0.6 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.4 C (a =4.35574 Å) and Mo 0.4 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.6 C ( a =4.40561Å).

[0014] Figure 3 shows the energy dispersive spectroscopy (EDS) analysis of the non-uniform high-entropy carbide ceramic material synthesized in this invention. As can be seen from Figure 3, the Mo synthesized by the method of this invention... 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1>The proportion of ceramic elements is consistent with the proportion of raw materials.

[0015] Figure 4 This is a SEM image of the non-uniform high-entropy carbide ceramic material synthesized in this invention. Figure 5 This is the EDS energy distribution diagram of the non-uniform high-entropy carbide ceramic material synthesized in this invention; from Figure 4 The microstructure of the Mo synthesized in this invention shows that 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) Ceramics are relatively dense with fewer defects; Figure 5 It can be seen that the Mo synthesized in this invention 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1>The six constituent elements in the ceramic are evenly distributed.

[0016] 2. Performance Evaluation

[0017] 2.1 Density and Mechanical Properties

[0018] (1) The bulk density of the material was measured using Archimedes' principle, and the theoretical density of the sample was calculated by combining the lattice constant and atomic mass obtained by XRD. The prepared Mo 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta1 / 4 ) x C ( x ≠0.8, 0< x <1) The bulk density, theoretical density and compaction density of the bulk material are shown in Table 1.

[0019] Table 1. Compactness of the high-entropy ceramic material of the present invention

[0020]

[0021] (2) Mo was tested using a Vickers microhardness tester. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x The hardness was <1). The test conditions were: load 200 gf, loading duration 10 s;

[0022] (3) Mo was tested using a nanoindenter 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) Nanoscale hardness and elastic modulus of ceramics. Test conditions: 6 test points were randomly selected, with a load of 8 mN and a loading duration of 10 s;

[0023] (4) Mo was determined using the three-point bending method. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) Bending strength of ceramics. The experimental span was 20 mm, the loading speed was 0.5 mm / min, and each set of data was repeated 4 to 6 times and the average value was taken.

[0024] (5) Mo was determined using the single-sided notched beam (SENB) method. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x<1) Fracture toughness of ceramics. The experimental span was 16 mm, the loading rate was 0.05 mm / min, and each set of data was repeated 4-6 times and the average value was taken. The test results are shown in Table 2. With the increase of Mo content, its mechanical properties all showed regular changes, among which Mo 0.4 (Ti 1 / 4Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.6 C ceramics have the best overall mechanical properties.

[0025] Table 2 Mechanical properties of the high-entropy ceramic material of the present invention at room temperature

[0026]

[0027] 2.2 High-temperature antioxidant properties

[0028] The high-temperature antioxidant properties were evaluated using a thermogravimetric analyzer, and the high-entropy carbide Mo was analyzed. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) The block was crushed and screened into powder using a crusher. The test conditions were air environment, the test temperature was room temperature to 1000℃, the heating rate was 10℃ / min, the test time was 100min, the heating was stopped at 1000℃ and then the block was allowed to cool naturally. Figure 6 For the prepared Mo 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) TG curve of ceramics. Within the oxidation range of room temperature to 1000℃, the TG curve was obtained by comparing the ceramic with an equimolar ratio of Mo. 0.2 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.8 A comparison with C revealed that Mo 0.6 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.4 C and Mo 0.8 (Ti 1 / 4 Zr 1 / 4 Nb1 / 4 Ta 1 / 4 ) 0.2 The TG curves of C ceramics all showed quality changes starting around 600℃, indicating that oxidation occurred first in these three components. Mo... 0.4 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.6 The TG curve of C ceramics only begins to show significant quality changes at around 800℃, demonstrating excellent oxidation resistance.

[0029] 2.3 High-Temperature Tribological Properties

[0030] The high-temperature tribological properties were tested using a high-temperature reciprocating friction and wear testing machine. The test temperature was 800℃, Al2O3 balls were used as the friction pair, the load was 10N, the reciprocating length was 5mm, and the test time was 30min. Figure 7 For the prepared Mo 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) Friction coefficient curve of ceramics at 800℃. At high temperatures, Mo oxidizes to form layered MoO3, which has a synergistic lubricating effect, thus significantly reducing the friction coefficient. Because Mo... 0.8 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4Ta 1 / 4 ) 0.2 C has the highest Mo content, and at 800℃, it can generate a large amount of MoO3, which acts as a lubricant, thereby improving tribological properties. (Compared to equimolar Mo...) 0.2 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.8 C ceramics, non-equimolar ratio Mo 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4Ta 1 / 4 ) x C ( x ≠0.2, 0 < x <1) It has excellent tribological properties at high temperatures.

[0031] III. Applications of Non-Uniform High-Entropy Ceramic Materials

[0032] This invention synthesizes non-uniform Mo by adjusting the Mo content. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) Ceramics are something that has not been reported before. Its synthesized series of Mo... 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1>In ceramics, Mo 0.4 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.6 C possesses superior mechanical properties and antioxidant properties, while Mo... 0.8 (Ti 1 / 4Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.2 C exhibits excellent tribological properties at high temperatures and is expected to be used as a high-temperature thermal protection material and high-temperature structural component, with significant application potential in structural components for aerospace and marine engines operating under extreme conditions.

[0033] In summary, the initial materials used in the method of this invention are relatively economical and cost-effective. The raw materials used are simple, common, commercially available, easy to obtain, and inexpensive, facilitating process implementation. Compared with existing high-entropy equiatomic high-entropy carbides, the non-equiatomic Mo prepared by this invention... 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1>The ceramic bulk materials, due to the presence of varying amounts of Mo, exhibit superior oxidation resistance and tribological properties. Furthermore, the method of this invention offers advantages such as simple preparation process, high controllability, and ease of large-scale production. Attached Figure Description

[0034] Figure 1 Mo prepared for this invention 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) Schematic diagram of the crystal structure of ceramics (a) and high-resolution transmission image (b).

[0035] Figure 2 Mo prepared in the embodiments of the present invention 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) XRD pattern of ceramics.

[0036] Figure 3 shows the Mo prepared in the embodiment of the present invention. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) Energy diagram analysis spectrum of ceramics, where a: x=0.2, b: x=0.4, c: x=0.6.

[0037] Figure 4 Mo prepared in the embodiments of the present invention 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) SEM image of ceramics.

[0038] Figure 5 Mo prepared in the embodiments of the present invention 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) EDS energy distribution diagram of ceramics.

[0039] Figure 6 Mo prepared in the embodiments of the present invention 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C (x ≠0.8, 0< x <1>Thermogravimetric curve of ceramics.

[0040] Figure 7 Mo prepared in the embodiments of the present invention 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1) Friction curve of ceramic. Detailed Implementation

[0041] The present invention Mo is illustrated below through examples. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) x C ( x ≠0.8, 0< x <1>A detailed explanation of the synthesis methods for ceramic bulk materials.

[0042] Example 1 High Entropy Mo 0.8 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.2 Preparation of C ceramics

[0043] (1) Mo2C powder, TiC powder, ZrC powder, NbC powder, TaC powder and graphite were mixed in a stoichiometric ratio of 1.6:0.2:0.2:0.2:0.2:1.6, and the total weight of the original materials was about 20g. The original materials were placed in a ball mill jar, and the ratio of tungsten carbide grinding balls to mixed materials was 5:1. Stearic acid of 1% of the total weight of the materials was added as the ball milling medium. The ball mill jar was placed in a planetary ball mill and ball milled at a speed of 300 r / min for 8 h under argon protection to obtain mixed powder.

[0044] (2) The dried mixed powder obtained in step (1) is pre-pressed into a green body using a hydraulic press at 30 MPa, and then hot-pressed and sintered. Hot-pressing and sintering process conditions: The atmosphere furnace is evacuated to ensure that the vacuum reading is <10. -1 Pa, then the furnace temperature was increased from room temperature to 1700℃ at a heating rate of 10℃ / min and held for 1 hour; subsequently, the power was turned off and the furnace was allowed to cool naturally to room temperature to obtain Mo. 0.8 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 )0.2 C ceramics.

[0045] Structure and performance such as Figures 1-7 As shown. The prepared Mo 0.8 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.2 C ceramics are face-centered cubic phases; the energy dispersive spectroscopy (EDS) shows that Mo... 0.8 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.2 The C ceramic element ratio is consistent with the raw material ratio; SEM images and element distribution maps show that the synthesized high-entropy Mo 0.8 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.2 C ceramics are relatively dense, have fewer defects, and their six constituent elements are evenly distributed.

[0046] The prepared Mo 0.8 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.2 The bulk density of C ceramic is 7.92 g / cm³. 3 The theoretical density is 9.19 g / cm³. 3 The density was 86.19%, the nanohardness was 24.9±0.3 GPa, the elastic modulus was 391.0±50.4 GPa, the Vickers hardness was 10.5±0.4 GPa, the flexural strength was 363.1±24.2 MPa, and the fracture toughness was 3.1±0.2 MPa·m. 1 / 2 .

[0047] Example 2 High Entropy Mo 0.6 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.4 Preparation of C ceramics

[0048] (1) Mo2C powder, TiC powder, ZrC powder, NbC powder, TaC powder and graphite were mixed in a stoichiometric ratio of 1.2:0.4:0.4:0.4:0.4:1.2, and the total weight of the original materials was about 20g. The original materials were placed in a ball mill jar, and the ratio of tungsten carbide grinding balls to mixed materials was 5:1. Stearic acid of 2% of the total weight of the materials was added as the ball milling medium. The ball mill jar was placed in a planetary ball mill and ball milled at a speed of 400 r / min for 9 h under argon protection to obtain mixed powder.

[0049] (2) The dried mixed powder obtained in step (1) is pre-pressed into a green body using a hydraulic press at 30 MPa, and then hot-pressed and sintered. Hot-pressing and sintering process conditions: The atmosphere furnace is evacuated to ensure that the vacuum reading is <10. -1 Pa, then the furnace temperature was increased from room temperature to 1800℃ at a heating rate of 10 ℃ / min and held for 2 hours; subsequently, the power was turned off and the furnace was allowed to cool naturally to room temperature to obtain Mo. 0.6 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.4 C ceramics.

[0050] Structure and performance such as Figures 1-7 As shown. The prepared Mo 0.6 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.4 C ceramics are face-centered cubic phases; the energy dispersive spectroscopy (EDS) shows that Mo... 0.6 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.4 The C ceramic element ratio is consistent with the raw material ratio; SEM images and element distribution maps show that the synthesized high-entropy Mo 0.6 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.4 C ceramics are relatively dense, have fewer defects, and their six constituent elements are evenly distributed.

[0051] The prepared Mo 0.6 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.4 The bulk density of C ceramic is 8.02 g / cm³. 3 The theoretical density is 8.91 g / cm³.3 The density was 89.97%, the nanohardness was 28.3±1.2 GPa, the elastic modulus was 414.7±14.7 GPa, the Vickers hardness was 14.4±0.5 GPa, the flexural strength was 365.9±44.4 MPa, and the fracture toughness was 3.3±0.2 MPa·m. 1 / 2 .

[0052] Example 3 High Entropy Mo 0.4 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.6 Preparation of C ceramics

[0053] (1) Mo2C powder, TiC powder, ZrC powder, NbC powder, TaC powder and graphite were mixed in a stoichiometric ratio of 0.8:0.6:0.6:0.6:0.6:0.8, with a total weight of about 20g. The raw materials were placed in a ball mill jar with a tungsten carbide grinding ball:mixture ratio of 5:1. Stearic acid, which accounts for 3% of the total weight of the raw materials, was added as the ball milling medium. The ball mill jar was placed in a planetary ball mill and ball milled at a speed of 500 r / min for 10 h under argon protection to obtain the mixed powder.

[0054] (2) The dried mixed powder obtained in step (1) is pre-pressed into a green body using a hydraulic press at 30 MPa, and then hot-pressed and sintered. Hot-pressing and sintering process conditions: The atmosphere furnace is evacuated to ensure that the vacuum reading is <10. -1 Pa, then the furnace temperature was increased from room temperature to 1900℃ at a heating rate of 10 ℃ / min and held for 1 hour; subsequently, the power was turned off and the furnace was allowed to cool naturally to room temperature to obtain Mo. 0.4 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.6 C ceramics.

[0055] Structure and performance such as Figures 1-7 As shown. The prepared Mo 0.4 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.6 C ceramics are face-centered cubic phases; the energy dispersive spectroscopy (EDS) shows that Mo... 0.4 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.6 The C ceramic element ratio is consistent with the raw material ratio; SEM images and element distribution maps show that the synthesized high-entropy Mo0.4 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.6 C ceramics are relatively dense, have fewer defects, and their six constituent elements are evenly distributed.

[0056] The prepared Mo 0.4 (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4 Ta 1 / 4 ) 0.6 The bulk density of C ceramic is 8.04 g / cm³. 3 The theoretical density is 8.73 g / cm³. 3 The density was 92.12%, the nanohardness was 30.5±2.0 GPa, the elastic modulus was 424.6±54.6 GPa, the Vickers hardness was 15.7±0.5 GPa, the flexural strength was 377.6±38.5 MPa, and the fracture toughness was 3.4±0.2 MPa·m. 1 / 2 .

Claims

1. A non-uniform high-entropy carbide ceramic material, characterized in that: Molybdenum 1-x (Titanium 1 / 4 Zirconium 1 / 4 Niobium 1 / 4 Tantalum 1 / 4 ) x C, 0.2≤x≤0.6, wherein the total amount of metal elements is 1.

2. A method for preparing a non-uniform high-entropy carbide ceramic material as described in claim 1, characterized in that, Includes the following steps: 1) Weigh Mo2C powder, TiC powder, ZrC powder, NbC powder, TaC powder, and graphite according to the stoichiometric ratio of each element in the above molecular formula. The purity of Mo2C powder, TiC powder, ZrC powder, NbC powder, TaC powder, and graphite is ≥99%, and the particle size is 1~3μm. Add 1%~6% stearic acid as a ball milling medium, and grind under an inert atmosphere to obtain a mixed powder. The grinding is carried out by placing the raw materials in the tungsten carbide ball mill jar of a ball mill and adding tungsten carbide grinding balls to grind into a mixed powder. During grinding, the mass ratio of grinding balls to mixed materials is 5:1~20:1; the speed of the ball mill is 200~600 rpm; and the ball milling time is 8~48 hours. 2) Press the target mixed powder obtained in step 1) into a green body, and then hot press and sinter the green body. During the hot pressing and sintering process, a vacuum is drawn at a pressure of 1.5~30 MPa and a vacuum degree <10. -1 Pa, heating rate of 5~10 ℃ / min, sintering temperature of 1700~2000 ℃, sintering time of 1~2 hours; After sintering and cooling, the target product Mo is obtained. 1-x (Ti 1 / 4 Zr 1 / 4 Nb 1 / 4Ta 1 / 4 ) x C-block ceramic.

Images