Preparation method of a six-membered layered high-entropy MAX phase ceramic

Abstract

This invention discloses a six-element layered high-entropy MAX phase (Ti 0.25 V 0.25 Nb 0.25 Ta 0.25 The preparation method of 4AlC3 ceramic involves mixing four metal powders, Al powder, and C powder in a certain proportion as raw materials, or using NbC and TaC carbide powders and pure metal powders of the remaining elements as raw materials for sintering reaction to prepare 413-type layered high-entropy MAX phase material. Using alcohol as the grinding medium, the raw materials are ball-milled in an argon atmosphere for 10-12 hours to obtain a mixed powder. The mixed powder is dried in a vacuum environment at 60°C for 10-24 hours. The dried mixed powder is then cold-pressed into a green body, followed by spark plasma sintering or hot pressing sintering to obtain the target layered high-entropy MAX phase material. Testing revealed that this 413-type high-entropy ceramic material is similar to the 211-type (Ti) ceramic material of the same element. 0.25 V 0.25 Nb 0.25 Ta 0.25 Compared to AlC MAX phase ceramics, this invention exhibits superior tribological properties over a wide temperature range, demonstrating greater potential for applications under extreme and complex conditions such as high temperature and high load. The process is simple, the raw materials are inexpensive, and it is easily scaled up for industrial production, laying the foundation for the application of high-entropy MAX phase materials in the field of friction.

Description

Technical Field

[0001] This invention belongs to the technical field of layered high-entropy ceramic materials, specifically relating to a hexa-element high-entropy MAX phase ceramic material and its preparation method. Background Technology

[0002] MAX phases are a class of carbides, nitrides, or carbonitrides with a layered microstructure and the molecular formula M. n+1 AX n In the MAX phase, n = 1, 2, 3, or 4, M is a pre-transition group element, A is mainly a group III, IV, or V element, and X is C or N. The bonds between M and X are ionic or covalent, and the bonds between M and A are metallic. Therefore, the MAX phase can combine the advantages of ceramics and metals, such as low density, high modulus, high damage tolerance, and good machinability.

[0003] The concept of "high entropy" originated from high entropy alloys. Ye Weijun proposed the concept of high entropy alloys in 2004, referring to multiple alloying elements dissolved together in near equimolar ratios to form a single-phase solid solution. High entropy ceramics inherit the design concept of high entropy alloys, consisting of single-phase ceramics composed of no fewer than four types of cations or anions. The "high entropy effect" caused by multiple principal elements improves the thermal stability of ceramic materials, while the solid solution strengthening and lattice distortion caused by "high entropy" further enhance the mechanical properties of the materials. The "cocktail" effect allows high entropy materials to outperform ceramic materials composed of individual elements.

[0004] High-entropy MAX phase ceramics are a newly emerging type of MAX phase material in recent years, exhibiting higher hardness, strength, and thermal stability compared to traditional MAX phase ceramics. The designability of high-entropy multi-principal elements allows for unique physical and chemical properties, with broad application prospects in aerospace and nuclear power structural materials, magnetism, and thermoelectric fields. Furthermore, the unique layered microstructure of MAX phases provides significant exploration potential and promising application prospects in the field of friction and wear. Currently, there is very little research on the synthesis of high-entropy 413-type MAX phase materials (Journal of the European Ceramic Society, 2021, 41(8): 4658-4665). The reported synthesis of 413-type MAX phases utilizes single-element 211-type MAX powder and requires the presence of a catalyst-like phase, which not only increases the synthesis difficulty but also the synthesis cost. Moreover, the catalyst-like phase ultimately exists in the target product as an intermetallic compound, preventing the target product from achieving a high-purity phase. Therefore, using low-cost pure metal powder or carbide powder and simple processes to synthesize novel high-entropy MAX phase materials is an inevitable choice to broaden the types of high-entropy MAX phase materials and expand their applications in the field of tribology. Summary of the Invention

[0005] This invention aims to address, to some extent, the current problems in the synthesis technology of type 413 high-entropy MAX phases. Therefore, the main objective of this invention is to provide a method for preparing hexa-layered high-entropy MAX phase ceramics with the molecular formula (Ti... 0.25 V 0.25 Nb 0.25 Ta 0.25 The 4AlC3 is characterized by the fact that the raw materials used in its synthesis do not require the high-cost 211-type single-element MAX phase. Instead, it uses elemental metals, metal carbides, elemental aluminum powder, and graphite powder as raw materials. The 413-type high-entropy MAX phase ceramic material synthesized according to this invention has superior tribological properties compared to the 211-type high-entropy MAX phase material of the same element, and the synthesis cost is low and the process is simple.

[0006] The technical solution provided by this invention is as follows: A method for preparing a six-element layered high-entropy MAX phase ceramic, comprising the following steps: (1) Mix M-site metal element powder, Al powder and C powder in proportion as raw materials. M-site metal powder includes Ti powder, V powder, Nb powder and Ta powder; or replace Nb powder and Ta powder with NbC and TaC carbide powder and mix them with Ti powder, V powder and Al powder in proportion as raw materials.

[0007] Among them, Ti powder, V powder, Nb powder, and Ta powder at the M site are mixed in an equimolar ratio, and the molar ratio of M site metal powder:Al powder:C powder is 2 : (1.1~1.2) : 0.9; the molar ratio of Ti powder:V powder:NbC powder:TaC powder:Al powder is 0.5 : 0.5 : 0.5 : 0.5 : (1.1~1.2). The purity of the above-mentioned raw materials Ti powder, V powder, Nb powder, Ta powder, NbC powder, TaC powder, Al powder, and C powder is ≥99%, and the powder particle size is not less than 325 mesh.

[0008] (2) The raw materials in step 1) are ball-milled for 10-12 hours under argon protection. 30%-40% of the total weight of the raw materials are added as anhydrous ethanol as the ball milling medium. After grinding, a mixed powder is obtained. The ball-to-material ratio of the ball mill is (2-3):1, and the ball milling speed is 200-400 rpm.

[0009] (3) Place the mixed powder from step 2) into a vacuum drying oven and dry it at 60°C for 10~24h to obtain dried mixed powder.

[0010] (4) The mixed powder from step 3) is cold-pressed into a blank, and then the blank is subjected to spark plasma sintering or hot pressing sintering to obtain the target product (Ti). 0.25 V 0.25 Nb 0.25 Ta 0.254AlC3 ceramics.

[0011] The spark plasma sintering is carried out in a vacuum environment with a vacuum degree ≤ 5.0E0 Pa, a pressure of 30~40 MPa, and a sintering time of 15~30 min; the heating rate is 50~120℃ / min, and the sintering temperature is 1300~1400 ℃.

[0012] Hot pressing sintering is carried out in a vacuum environment with a vacuum degree ≤10. -3 The pressure is 30~40 MPa, the sintering time is 1~2h, the heating rate is 5~10 ℃ / min, and the sintering temperature is 1600~1650 ℃.

[0013] The synthesis mechanism of this invention is as follows: As shown in the above formula, the 211-type MAX phase, compared to the 413-type MAX phase, is supersaturated with Al and deficient with C. The C deficiency is beneficial to the stable existence of the MAX phase. Furthermore, when the sintering temperature reaches 650°C, the Al powder in the raw material volatilizes, and when the temperature rises to a certain level, the 211-type MAX phase can decompose, releasing and volatilizing Al from the material to generate a high-entropy MAX phase. Therefore, under suitable sintering processes, promoting the decomposition of the 211-type high-entropy MAX phase and the volatilization of Al can yield the 413-type high-entropy MAX phase.

[0014] Parameters that promote Al volatilization and the decomposition of the 211-type MAX phase include increasing the synthesis temperature and increasing the holding time. In Example 4, which describes an increase in temperature based on the comparative high-entropy 211-type MAX phase synthesis process, a MAX phase composite material with 211-type and 413-type (mainly) phases was obtained, indicating that the 211-type MAX phase had decomposed. In Example 6, where the holding time was further increased based on Example 4, the 211-type MAX phase completely disappeared, and a small amount of carbide phase appeared, indicating that the 211 phase decomposition was complete. Even the 413-type MAX phase underwent a small amount of decomposition to form carbide phases, verifying the proposed high-entropy 413-type MAX phase synthesis mechanism.

[0015] The present invention has the following beneficial effects: This invention provides a six-element layered high-entropy MAX phase (Ti 0.25 V 0.25 Nb 0.25 Ta 0.25The preparation method of AlC3 ceramics uses pure metal powder, or some metal carbide powder and C powder as raw materials. The design cost is lower than that of existing processes, the synthesis process is simpler, and the target product is free from impurity element contamination. The high-entropy MAX phase material prepared has better tribological properties in a wider temperature range than the 211 type high-entropy MAX phase material of the same element. Attached Figure Description

[0016] Figure 1 SEM microstructure images of the ceramic materials in Examples 1 and 2; Figure 2 XRD characterization results of ceramic materials in Examples 1 and 2; Figure 3 Surface morphology of ceramic materials in Examples 1 and 2; Figure 4 Example 3: XRD characterization results of ceramic materials; Figure 5 Example 3: SEM cross-sectional and section characterization images of ceramic materials; Figure 6 XRD characterization results of ceramic materials in Examples 4 and 5; Figure 7 SEM cross-sectional and section characterization images of ceramic materials in Examples 4 and 5; Figure 8 Example 6: XRD characterization results of ceramic materials; Figure 9 Comparative Example (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 Microstructure of AlC MAX phase ceramic material; Figure 10 Comparative Example (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 XRD analysis results of 2AlC MAX phase ceramic materials. Detailed Implementation

[0017] To further clarify the objectives, technical solutions, and advantages of this invention, detailed descriptions are provided below with reference to embodiments. It should be understood that these embodiments are merely illustrative of the invention and are not intended to limit the scope of protection of the invention. All technologies implemented based on the above description of this invention are covered within the intended scope of protection of this invention.

[0018] All raw materials used in this embodiment are commercially available products.

[0019] In the following embodiments and comparative examples of the present invention, the friction coefficient and wear rate of materials in the range of room temperature to 800°C were tested using the Zhongke Kaihua HT-1200 friction testing machine, and the test conditions were the same.

[0020] Example 1 Type 413 hexa-level high-entropy (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 The preparation method of AlC3MAX phase ceramic materials includes the following steps: 1) Prepare the ingredients according to the molar ratio Ti : V : Nb : Ta : Al : C = 0.5 : 0.5 : 0.5 : 0.5 : 1.2 : 0.9, with a total weight of 30g.

[0021] 2) Place the raw material in a zirconia-lined vacuum ball mill jar with a mass percentage of zirconia balls to raw material = 2:1; add anhydrous ethanol as the ball milling medium, with an ethanol to raw material mass ratio of 40%; then evacuate the ball mill jar and purge it with argon gas, repeating this operation 3 times; place the ball mill jar in a planetary ball mill, with a ball milling speed of 280 rpm and a ball milling time of 10 h to obtain a mixed powder.

[0022] 3) Place the mixed powder from step 2) into a vacuum drying oven and dry it at a temperature of 60°C and a vacuum degree of -0.08MPa for 10 hours. Turn off the heating device and wait for the sample to cool to room temperature before taking it out.

[0023] 4) The dried and mixed powder from step 3) is cold-pressed to obtain a preform. The preform is placed in a corresponding graphite mold, and then subjected to spark plasma sintering in a vacuum environment. The sintering process is as follows: the sintering furnace is evacuated to below 5.0E0 Pa at room temperature, the temperature is increased to 600°C at 120°C / min, then increased to 1320°C at 50°C / min, held for 20 min, and the loading pressure is 30 MPa. After the holding period, the pressure and temperature are immediately reduced, and the sample is cooled with the furnace to prepare (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase ceramic materials.

[0024] Example 2 Type 413 hexa-level high-entropy (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 The preparation method of AlC3MAX phase ceramic materials includes the following steps: 1) Prepare the ingredients according to the molar ratio Ti : V : Nb : Ta : Al : C = 0.5 : 0.5 : 0.5 : 0.5 : 1.2 : 0.9, with a total weight of 20g.

[0025] 2) Place the raw material in a zirconia-lined vacuum ball mill jar with a mass percentage ratio of zirconia balls to raw material of 3:1; add anhydrous ethanol as the milling medium, with an ethanol-to-raw material mass ratio of 40%; then evacuate the ball mill jar and purge it with argon gas, repeating this operation 3 times; place the ball mill jar in a planetary ball mill, mill at a speed of 300 rpm for 12 hours to obtain a mixed powder.

[0026] 3) Place the mixed powder from step 2) into a vacuum drying oven and dry it at a temperature of 60°C and a vacuum degree of -0.08MPa for 15 hours. Turn off the heating device and wait for the sample to cool to room temperature before taking it out.

[0027] 4) The dried and mixed powder from step 3) is cold-pressed to obtain a preform. The preform is placed in a corresponding graphite mold, and then subjected to spark plasma sintering in a vacuum environment. The sintering process is as follows: the sintering furnace is evacuated to below 5.0E0 Pa at room temperature, the temperature is increased to 600°C at 120°C / min, then increased to 1400°C at 50°C / min, held for 20 min, and the loading pressure is 30 MPa. After the holding period, the pressure and temperature are immediately reduced, and the sample is cooled with the furnace to prepare (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase ceramic materials.

[0028] Example 3 Type 413 hexa-level high-entropy (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 The preparation method of AlC3MAX phase ceramic materials includes the following steps: 1) Prepare the ingredients according to the molar ratio Ti : V : NbC : TaC : Al = 1 : 1 : 1 : 1 : 2.4, with a total weight of 30g.

[0029] 2) Place the raw material in a zirconia-lined vacuum ball mill jar with a mass percentage ratio of zirconia balls to raw material of 2:1; add anhydrous ethanol as the milling medium, with an ethanol-to-raw material mass ratio of 40%; then evacuate the ball mill jar and purge it with argon gas, repeating this operation 3 times; place the ball mill jar in a planetary ball mill, with a milling speed of 280 rpm and a milling time of 12 hours to obtain a mixed powder.

[0030] 3) Place the mixed powder from step 2) into a vacuum drying oven and dry it at a temperature of 60°C and a vacuum degree of -0.08MPa for 15 hours. Turn off the heating device and wait for the sample to cool to room temperature before taking it out.

[0031] 4) The dried and mixed powder from step 3) is cold-pressed to form a blank. The blank is placed in a corresponding graphite mold, and then hot-pressed and sintered under vacuum. The sintering process is as follows: the sintering furnace is evacuated to 10°C at room temperature. -3 Below Pa, the temperature was increased to 1600°C at a rate of 10°C / min, held for 90 min, and a loading pressure of 30 MPa was applied. After the holding period, the pressure and temperature were immediately reduced, and the sample was cooled with the furnace to prepare (Ti). 0.25 V 0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase ceramic materials.

[0032] Example 4 Type 413 hexa-level high-entropy (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 The preparation method of AlC3MAX phase ceramic materials includes the following steps: 1) Prepare the ingredients according to the molar ratio Ti : V : NbC : TaC : Al = 1 : 1 : 1 : 1 : 2.4, with a total weight of 20g.

[0033] 2) Place the raw material in a zirconia-lined vacuum ball mill jar with a mass percentage ratio of zirconia balls to raw material of 3:1; add anhydrous ethanol as the milling medium, with an ethanol-to-raw material mass ratio of 40%; then evacuate the ball mill jar and purge it with argon gas, repeating this operation 3 times; place the ball mill jar in a planetary ball mill, with a milling speed of 280 rpm and a milling time of 10 h to obtain a mixed powder.

[0034] 3) Place the mixed powder from step 2) into a vacuum drying oven and dry it at a temperature of 60°C and a vacuum degree of -0.08MPa for 10 hours. Turn off the heating device and wait for the sample to cool to room temperature before taking it out.

[0035] 4) The dried and mixed powder from step 3) is cold-pressed to form a blank. The blank is placed in a corresponding graphite mold, and then hot-pressed and sintered under vacuum. The sintering process is as follows: the sintering furnace is evacuated to 10°C at room temperature. -3 Below Pa, the temperature was increased to 1600°C at 10°C / min, then increased to 1650°C at 5°C / min, and held for 90 min. A loading pressure of 30 MPa was applied. After the holding period, the pressure and temperature were immediately reduced, and the sample was cooled with the furnace to prepare (Ti). 0.25 V0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase ceramic materials.

[0036] Example 5 Type 413 hexa-level high-entropy (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 The preparation method of AlC3MAX phase ceramic materials includes the following steps: 1) Prepare the ingredients according to the molar ratio Ti : V : NbC : TaC : Al = 1 : 1 : 1 : 1 : 2.2, with a total weight of 30g.

[0037] 2) Place the raw material in a zirconia-lined vacuum ball mill jar with a mass ratio of zirconia balls to raw material of 2:1; add anhydrous ethanol as the milling medium, with an ethanol-to-raw material mass ratio of 40%; then evacuate the ball mill jar and purge it with argon gas, repeating this operation 3 times; place the ball mill jar in a planetary ball mill, with a milling speed of 280 rpm and a milling time of 10 h to obtain a mixed powder.

[0038] 3) Place the mixed powder from step 2) into a vacuum drying oven and dry it at a temperature of 60°C and a vacuum degree of -0.08MPa for 10 hours. Turn off the heating device and wait for the sample to cool to room temperature before taking it out.

[0039] 4) The dried and mixed powder from step 3) is cold-pressed to form a blank. The blank is placed in a corresponding graphite mold, and then hot-pressed and sintered under vacuum. The sintering process is as follows: the sintering furnace is evacuated to 10°C at room temperature. -3 Below Pa, the temperature was increased to 1600°C at 10°C / min, then increased to 1650°C at 5°C / min, and held for 90 min. A loading pressure of 30 MPa was applied. After the holding period, the pressure and temperature were immediately reduced, and the sample was cooled with the furnace to prepare (Ti). 0.25 V 0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase ceramic materials.

[0040] Example 6 Type 413 hexa-level high-entropy (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 The preparation method of AlC3MAX phase ceramic materials includes the following steps: 1) Prepare the ingredients according to the molar ratio Ti : V : NbC : TaC : Al = 1 : 1 : 1 : 1 : 2.4, with a total weight of 30g.

[0041] 2) Place the raw material in a zirconia-lined vacuum ball mill jar with a mass percentage ratio of zirconia balls to raw material of 2:1; add anhydrous ethanol as the milling medium, with an ethanol-to-raw material mass ratio of 40%; then evacuate the ball mill jar and purge it with argon gas, repeating this operation 3 times; place the ball mill jar in a planetary ball mill, mill at a speed of 300 rpm, and mill for 10 hours to obtain a mixed powder.

[0042] 3) Place the mixed powder from step 2) into a vacuum drying oven and dry it at a temperature of 60°C and a vacuum degree of -0.08MPa for 10 hours. Turn off the heating device and wait for the sample to cool to room temperature before taking it out.

[0043] 4) The dried and mixed powder from step 3) is cold-pressed to form a blank. The blank is placed in a corresponding graphite mold, and then hot-pressed and sintered under vacuum. The sintering process is as follows: the sintering furnace is evacuated to 10°C at room temperature. -3 Below Pa, the temperature was increased to 1600℃ at 10℃ / min, then increased to 1650℃ at 5℃ / min, and held for 120 min. A loading pressure of 30 MPa was applied. After the holding period, the pressure and temperature were immediately reduced, and the sample was cooled with the furnace to prepare (Ti). 0.25 V 0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase ceramic materials.

[0044] Comparative Example Type 211 hexa-level high-entropy (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 The preparation steps of 2AlC MAX phase ceramic materials are as follows: 1) Prepare the ingredients according to the molar ratio Ti : V : Nb : Ta : Al : C = 0.5 : 0.5 : 0.5 : 0.5 : 1.2 : 0.9, with a total weight of 20g.

[0045] 2) Place the raw material in a zirconia-lined vacuum ball mill jar with a mass percentage ratio of zirconia balls to raw material of 3:1; add anhydrous ethanol as the milling medium, with an ethanol-to-raw material mass ratio of 40%; then evacuate the ball mill jar and purge it with argon gas, repeating this operation 3 times; place the ball mill jar in a planetary ball mill, mill at a speed of 280 rpm, and mill for 12 hours to obtain a mixed powder.

[0046] 3) Place the mixed powder from step 2) into a vacuum drying oven and dry it at a temperature of 60°C and a vacuum degree of -0.08MPa for 10 hours. Turn off the heating device and wait for the sample to cool to room temperature before taking it out.

[0047] 4) The dried and mixed powder from step 3) is cold-pressed to form a blank. The blank is placed in a corresponding graphite mold, and then hot-pressed and sintered under vacuum. The sintering process is as follows: the sintering furnace is evacuated to 10°C at room temperature. -3 Below Pa, the temperature was increased to 1500°C at a rate of 10°C / min, held for 90 min, and a loading pressure of 30 MPa was applied. After the holding period, the pressure and temperature were immediately reduced, and the sample was cooled with the furnace to prepare (Ti). 0.25 V 0.25 Nb 0.25 Ta 0.25 )2AlC MAX phase ceramic materials.

[0048] Product Characterization Examples 1 and 2: (Ti) prepared by spark plasma sintering 0.25 V 0.25 Nb 0.25 Ta 0.25 )4. SEM image of the fracture surface of AlC3MAX phase ceramic material as shown in the figure Figure 1 As shown, the XRD pattern is as follows Figure 2 As shown, the surface morphology SEM image and EDS energy dispersive spectroscopy analysis of elemental atomic ratios are as follows: Figure 3 As shown in Table 1.

[0049] The SEM fracture surface image reveals a typical layered structure of the MAX phase. XRD phase analysis shows the presence of both a type 413 high-entropy MAX phase and a type 211 high-entropy MAX phase. Figure 3 The contrast between the two phases was analyzed using ImageJ area statistics. The results showed that the proportion of the 413-type high-entropy MAX phase (brighter in contrast) was 70.6% in Example 1 and 84% in Example 2. EDS energy dispersive spectroscopy analysis, as shown in Table 1, revealed that the proportions of elements at the M site in both MAX phases were approximately equimolar. The molar ratio of elements at the M, A, and X sites in the 413-type phase was M:A:C = 49.55:17.67:32.78 ≈ 4:1:3, while the molar ratio of elements in the 211-type phase was M:A:C = 45.24:26.60:21.57 ≈ 2:1:1, consistent with the XRD characterization results. Therefore, the 413-type high-entropy (Ti) MAX phase was successfully prepared. 0.25 V 0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase-based ceramic materials.

[0050] Table 1. (Ti) prepared in Example 1 0.25 V 0.25 Nb 0.25 Ta 0.25 Atomic percentage table of AlC3MAX phase ceramic materials Example 3: The XRD characterization structure of the high-entropy ceramic obtained is as follows. Figure 4 As shown, the results indicate that the synthesized materials are 413-type and 211-type MAX phase ceramic materials. The cross-sectional and surface morphologies are as follows. Figure 5 As shown, it also exhibits a typical MAX phase layered structure. According to the phase contrast statistics, the 413 type (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 The 4AlC3MAX phase accounts for 76.6%. Therefore, a high-entropy (Ti413) phase was successfully prepared. 0.25 V 0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase-based ceramic materials.

[0051] The XRD characterization structures of the high-entropy ceramics obtained in Examples 4 and 5 are as follows: Figure 6 As shown, the results indicate that the synthesized material is a mixed ceramic material of type 413 and type 211 MAX phases. The cross-sectional and surface morphology are as follows. Figure 7 As shown, a typical MAX phase layered structure, based on phase contrast statistics, is present in Example 4, type 413 (Ti). 0.25 V 0.25 Nb 0.25 Ta 0.25 The proportion of the 4AlC3MAX phase is 88%, and in Example 5, the 413 type (Ti) phase accounts for 88%. 0.25 V 0.25 Nb 0.25 Ta 0.25 The 4AlC3MAX phase accounted for 86.3%. Therefore, a high-purity 413-type high-entropy (Ti) phase was successfully prepared. 0.25 V 0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase ceramic materials.

[0052] Example 6 XRD phase analysis as follows Figure 8 As shown, under this process, type 211 (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 The 2AlCMAX phase disappears, leaving the Ti phase. 0.25 V0.25 Nb 0.25 Ta 0.25 The 4AlC3MAX phase also contains a small amount of carbide phases, forming a near-pure high-entropy 413 type (Ti) phase. 0.25 V 0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase.

[0053] In the comparative example (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 The microstructure of AlC MAX phase ceramic materials is shown in the SEM images, EDS energy dispersive spectroscopy analysis of elemental atomic ratios, and XRD patterns. Figures 9-10 As shown in Table 2.

[0054] Table 2 Comparative preparations of (Ti) 0.25 V 0.25 Nb 0.25 Ta 0.25 Atomic ratio percentage table of AlC MAX phase ceramic materials SEM images show that its microstructure is a typical MAX phase layered structure. EDS characterization shows that the proportions of elements at the M site are close to equimolar, and the molar ratio of elements at the M, A, and X sites is M:A:C = 47.11:24.57:21.35 ≈ 2:1:1. XRD characterization results show that the diffraction peaks are high-entropy (Ti). 0.25 V 0.25 Nb 0.25 Ta 0.25 The 2AlC MAX phase peaks were almost entirely free of impurities, thus successfully preparing the 211-type high-entropy (Ti) phase peaks. 0.25 V 0.25 Nb 0.25 Ta 0.25 )2AlC MAX phase ceramic materials.

[0055] Performance Evaluation The results of the wide-temperature-range tribological properties of the high-entropy MAX phase ceramic materials prepared in Example 6 and the comparative example under the same conditions are shown in Table 3 below. The friction conditions are: load of 5N, grinding pair of Si3N4, reciprocating distance of 5 mm, and frequency of 300 rpm.

[0056] Table 3. Comparison of frictional properties between Example 6 and the comparative example. As can be seen from the table above, Example 6 exhibits superior tribological properties, particularly effectively reducing the wear rate in the 400–800°C range. This is achieved by using the 413-type high-entropy (Ti) material obtained in this example. 0.25 V 0.25 Nb 0.25 Ta 0.25 )4AlC3MAX phase ceramic materials have superior performance compared to the 211 type MAX phase of the same element.

[0057] In summary, the hexa-layered high-entropy MAX phase (Ti) provided by this invention... 0.25 V 0.25 Nb 0.25 Ta 0.25 )4. Preparation method of AlC3 ceramics, the prepared ceramic material is superior to that of type 211 (Ti) of the same element. 0.25 V 0.25 Nb 0.25 Ta 0.25 2AlC MAX phase ceramic materials have better tribological properties over a wide temperature range. The raw materials used are pure metal elements, graphite powder or single-element carbide powder. The preparation process is simple, low-cost and reproducible, and easy to scale up for industrial production. This lays the foundation for the synthesis of new high-entropy MAX phase materials and their application in the field of friction.

[0058] The above description only illustrates the embodiments of the present invention and is not intended to limit the invention. The present invention can be modified and varied in various ways. 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. A method for preparing a six-element layered high-entropy MAX phase ceramic, characterized in that, The preparation steps are as follows: (1) Mix M-site metal element powder, Al powder and C powder in proportion as raw materials. M-site metal powder includes Ti powder, V powder, Nb powder and Ta powder; or replace Nb powder and Ta powder with NbC and TaC carbide powder and mix them with Ti powder, V powder and Al powder in proportion as raw materials. (2) The raw materials in step 1) are ball-milled for 10-12 hours under argon protection, and 30%-40% of the total weight of the raw materials are added as anhydrous ethanol as the ball milling medium. After grinding, a mixed powder is obtained. (3) Place the mixed powder from step 2) into a vacuum drying oven and dry it at 60°C for 10-24 hours to obtain dried mixed powder; (4) The mixed powder from step 3) is cold-pressed into a blank, and then the blank is subjected to spark plasma sintering or hot pressing sintering. After sintering, a high entropy (Ti413) type high entropy powder is obtained. 0.25 V 0.25 Nb 0.25 Ta 0.25 Ceramics with AlC3MAX phase as the main phase; The discharge plasma sintering is carried out in a vacuum environment with a vacuum degree ≤ 5.0E0 Pa, a pressure of 30~40 MPa, a sintering time of 15~30 min, a heating rate of 50~120 ℃ / min, and a sintering temperature of 1300~1400 ℃. The hot pressing sintering is carried out in a vacuum environment with a vacuum degree ≤10. -3 The pressure is 30~40 MPa, the sintering time is 1~2h, the heating rate is 5~10 ℃ / min, and the sintering temperature is 1600~1650 ℃.

2. The method for preparing a six-element layered high-entropy MAX phase ceramic as described in claim 1, characterized in that, In step 1), Ti powder, V powder, Nb powder, and Ta powder at site M are mixed in an equimolar ratio. The molar ratio of metal powder at site M: Al powder: C powder is 2: (1.1~1.2): 0.9; the molar ratio of Ti powder: V powder: NbC powder: TaC powder: Al powder is 0.5: 0.5: 0.5: 0.5: (1.1~1.2).

3. The method for preparing a six-element layered high-entropy MAX phase ceramic as described in claim 1, characterized in that, In step 1), the purity of the raw materials Ti powder, V powder, Nb powder, Ta powder, NbC powder, TaC powder, Al powder, and C powder is ≥99%, and the powder particle size is not less than 325 mesh.

4. The method for preparing a six-element layered high-entropy MAX phase ceramic as described in claim 1, characterized in that, In step 3), the ball-to-material ratio of the ball mill is (2~3):1, and the ball mill speed is 200~400 rpm.

5. A hexa-layered high-entropy MAX phase ceramic prepared by the method described in claim 1.

6. The application of a hexa-layered high-entropy MAX phase ceramic prepared by the method described in claim 1 in high-temperature friction components.

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