Preparation method of novel fluorite type high-entropy oxide ceramic

Abstract

The invention relates to the technical field of high-entropy oxide ceramics, in particular to a preparation method of novel fluorite type high-entropy oxide ceramics. By controlling the molar ratio of the raw materials and mixing the raw materials through ball milling, all the components are ensured to be uniformly mixed on the atomic scale, and component segregation is avoided. Diffusion and solid solution among all elements are promoted through sintering treatment, a stable fluorite type single-phase structure is formed, a large number of point defects and lattice distortion are introduced through the high-entropy effect, the lattice heat conductivity is reduced, the heat insulation performance of the material is improved, and the heat insulation performance of the material is improved by regulating and controlling the sintering process and heat treatment parameters and optimizing the grain boundary structure and phase composition. The fracture toughness and the thermal shock resistance of the material are improved, so that the technical problems of high preparation cost and poor toughness of the existing novel fluorite type high-entropy oxide ceramic are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-entropy oxide ceramics, and particularly relates to a preparation method of a novel fluorite-type high-entropy oxide ceramic. Background Art

[0002] In the vast field of materials science, high-entropy oxide ceramics, as a research hotspot emerging in recent years, are gradually showing their unique charm and broad application prospects. The concept of high entropy was initially developed from high-entropy alloys and has subsequently been gradually extended to other material systems, including high-entropy metallic glasses, high-entropy ceramics, etc. Among them, high-entropy oxide ceramics have attracted extensive attention in the academic community due to their unique "high-entropy effect" and excellent properties, especially their performance in low thermal conductivity.

[0003] High-entropy ceramics generally refer to solid solutions formed by five or more ceramic components, and their entropy values are much higher than those of traditional ceramic materials. Entropy is a parameter in thermodynamics that characterizes the degree of disorder of a substance. High entropy means a higher degree of disorder in the distribution of elements within the system. This degree of disorder helps to stabilize the single-phase structure of the material and generates a series of unique physical and chemical properties. In terms of low thermal conductivity, high-entropy oxide ceramics perform excellently. Since the constituent element atoms in high-entropy materials are randomly distributed on the lattice, it leads to an increase in phenomena such as lattice distortion, slip, and dislocation. These distortions have a significant impact on the properties of the material. In particular, the kinetic retardation diffusion effect of the high-entropy ceramic structure makes the heat conduction speed in the ceramic slow, thus helping to reduce the thermal conductivity of the material. This property makes high-entropy oxide ceramics have potential application value in fields such as high-temperature thermal insulation and thermal barrier coatings.

[0004] However, the main problem in the current preparation of high-entropy oxide ceramics is that the thermal conductivity of the samples is relatively low, but the toughness is poor. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a preparation method of a novel fluorite-type high-entropy oxide ceramic, which solves the technical problem of poor toughness existing in existing high-entropy oxide ceramics.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: The present invention provides a preparation method of a novel fluorite-type high-entropy oxide ceramic, including the following steps: using TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 and Cr 2 O 3 as raw materials, and according to (Al 0.2 Ti0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O 2 Weigh the molar ratios of the respective metal elements, and after wet ball milling and mixing evenly, a precursor is prepared; after the precursor is dried, it is subjected to dry ball milling and screening, and then cold pressed to obtain a green body; after the green body is sintered, a novel fluorite-type high-entropy oxide ceramic with a single-phase structure of AlTiTaO is obtained; wherein, the sintering method is microwave sintering or muffle furnace sintering.

[0007] Optionally, the microwave sintering includes the following steps: heating at a heating rate of 20 °C / min to 100 °C / min until the reflection power is stable, and then maintaining the heating rate at 20 °C / min to 30 °C / min until the sintering temperature reaches 950 °C to 1200 °C, and holding for 10 min to 60 min under the sintering temperature condition.

[0008] Optionally, the muffle furnace sintering includes the following steps: the heating rate is 5 °C / min, the sintering temperature is 1200 °C to 1500 °C, the holding time is 2 h to 6 h, and after the holding time ends, it is slowly cooled to room temperature with the furnace.

[0009] Optionally, the molar ratio of TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 and Cr 2 O 3 is 0.2:0.1:0.1:0.1:0.1.

[0010] Optionally, the dimensions of the cold pressing are 30 mm to 60 mm, the pressure is 30 MPa to 80 MPa, and the pressure holding time is 1 s to 120 s.

[0011] Optionally, the average particle size of the raw materials is 1 μm to 3 μm, and the average particle size of the precursor is 0.1 μm to 1 μm.

[0012] The present invention provides a novel fluorite-type high-entropy oxide ceramic, and the novel fluorite-type high-entropy oxide ceramic is prepared by using the preparation method of the above novel fluorite-type high-entropy oxide ceramic.

[0013] Optionally, the chemical formula of the novel fluorite-type high-entropy oxide ceramic is (Al 0.2 Ti 0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O 2 .

[0014] Optionally, the novel fluorite-type high-entropy oxide ceramic has a single-phase structure of AlTiTaO.

[0015] The beneficial effects of the present invention are as follows. Compared with the prior art, the present invention uses TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 and Cr 2 O 3 as raw materials. By controlling the molar ratio of the raw materials and the way of ball-milling and mixing the raw materials, it is ensured that each component is uniformly mixed at the atomic scale, avoiding composition segregation. Through sintering treatment, the diffusion and solid solution between elements are promoted to form a stable fluorite-type single-phase structure. By introducing a large number of point defects and lattice distortions using the high-entropy effect, the lattice thermal conductivity is reduced, and the heat insulation performance of the material is improved. By regulating the sintering process and heat treatment parameters, the grain boundary structure and phase composition are optimized, and the fracture toughness and thermal shock resistance of the material are improved, so that the prepared novel fluorite-type high-entropy oxide ceramic has a relatively low thermal conductivity and a relatively high fracture toughness, thus solving the technical problem of poor toughness existing in the prior high-entropy oxide ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic XRD diagram of the novel fluorite-type high-entropy oxide ceramic prepared in Example 5 of the present invention.

[0017] Figure 2 It is a SEM micrograph of the cross-section of the novel fluorite-type high-entropy oxide ceramic prepared in Example 5 of the present invention.

[0018] Figure 3 It is an EDS element distribution map of the cross-section of the novel fluorite-type high-entropy oxide ceramic prepared in Example 5 of the present invention. Among them, (a) is the EDS element distribution map of the cross-section, (b) is the distribution map of Nb element, (c) is the distribution map of Ta element, (d) is the distribution map of Ti element, (e) is the distribution map of Al element, and (f) is the distribution map of Cr element. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] To solve the above technical problems, the present invention provides a preparation method of a novel fluorite-type high-entropy oxide ceramic. Now, the technical solutions and embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0020] The experimental methods and detection means mentioned in this article are all regarded as conventional methods without specific instructions; the reagents and raw materials involved are also regarded as commercially available products unless otherwise specified.

[0021] The technical solution adopted by the present invention is as follows: A preparation method of a novel fluorite-type high-entropy oxide ceramic, comprising the following steps: Step 1, mixing five oxide powders of TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Cr 2 O 3 with absolute ethanol in a certain molar ratio and a certain proportion, and then putting them into a nylon ball milling tank for sufficient ball milling to prepare a mixed raw material.

[0022] Step 2, drying the sample after ball milling treatment in Step 1 in a constant temperature drying oven. Then, dry grind the dried mixed raw material again, sieve it and put it into a briquetting mold, and apply a certain pressure to form a green body.

[0023] Step 3, turn on the microwave source, adjust the microwave input power, heat up at a heating rate of 20°C / min to 100°C / min in the low temperature stage until the reflection power is stable, and then maintain the heating rate at 20°C / min to 30°C / min until the sintering temperature reaches 950°C to 1200°C, keep warm for 10 min to 60 min under the sintering temperature condition, and quickly cool to room temperature to prepare the novel fluorite-type high-entropy oxide ceramic.

[0024] Preferably, in Step 1, the molar ratio of the five oxides TiO 2 : Al 2 O 3 : Nb 2 O 5 : Ta 2 O 5 : Cr 2 O 3 is 0.2:0.1:0.1:0.1:0.1.

[0025] Preferably, in Step 1, the purity specifications of the 5 kinds of oxide powders used are that the diameters of the powder raw materials are all 1μm to 3μm; the average particle size of the mixed powder after ball milling is 0.1μm to 1μm.

[0026] Preferably, in Step 2, the temperature of the drying oven is 80°C to 100°C, and the drying time is 24 h. The sieve is a 100-mesh sieve. After collecting the dried material, it is prepared into a powder, and the methods include but are not limited to grinding method, ball milling method, and mechanical crushing method.

[0027] Preferably, in step 2, the die diameter is 30 mm to 60 mm, the pressure is 30 MPa to 80 MPa, and the pressure holding time is 1 s to 120 s.

[0028] Preferably, in step 3, the auxiliary heating and heat preservation combined device used for sintering has a SiC auxiliary heating body, including but not limited to rod-shaped or ring-shaped structures.

[0029] Preferably, in step 3, the sintering method is microwave sintering, the sintering temperature is 950 °C to 1250 °C, the heat preservation time is 10 min to 60 min, the total sintering time is 60 min to 120 min. The sintering method can also be non-pressure sintering in a muffle furnace, the heating rate is 5 °C / min, the sintering temperature is 1200 °C to 1500 °C, the heat preservation time is 2 h to 6 h, and after the heat preservation time ends, it is slowly cooled to room temperature with the furnace.

[0030] The present invention will be described in detail below through specific embodiments. The embodiments are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0031] Example 1 A preparation method of a novel fluorite-type high-entropy oxide ceramic, comprising the following steps: Step 1: Five oxide powders TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Cr 2 O 3 are formulated into a mixed raw material according to a molar ratio of 0.2:0.1:0.1:0.1:0.1. The purity specifications of the 5 kinds of oxide powders used are that the diameters of the powder raw materials are all 2 μm; the average particle size of the mixed powder after ball milling is 0.5 μm.

[0032] Step 2: Put the mixed raw material obtained in step 1 into a drying oven, the temperature of the drying oven is 90 °C, and the drying time is 24 h. The sieve mesh is 100-mesh sieve. After the dried material is collected, it is prepared into a powder. Weigh 15 g and put it into a briquetting die. The die diameter is 30 mm, the pressure provided by the press is 30 MPa, and the pressure holding time is 60 s.

[0033] Step 3: Put the green body obtained in step 2 into the auxiliary heating body for sintering. The sintering method is microwave sintering, the heating frequency is 2450 MHz, the maximum input power is 8 kW. In the low-temperature stage, it is heated to a stable reflection power at 40 °C / min, and then the heating rate is maintained at 30 °C / min until 950 °C, and it is kept warm for 30 min, and then it is slowly cooled to room temperature with the furnace to prepare a ceramic with the chemical formula (Al 0.2 Ti0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O 2 novel fluorite-type high-entropy oxide ceramic.

[0034] Example 2 A preparation method of a novel fluorite-type high-entropy oxide ceramic, comprising the following steps: Step 1: Prepare a mixed raw material by mixing five oxide powders TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Cr 2 O 3 in a molar ratio of 0.2:0.1:0.1:0.1:0.1. The purity specifications of the 5 kinds of oxide powders used are that the diameters of the powder raw materials are all 3 μm, and the average particle size of the mixed powder after ball milling is 1 μm.

[0035] Step 2: Put the mixed raw material obtained in Step 1 into a drying oven at a temperature of 80 °C for 24 h. The sieve mesh is 100 mesh. After the dried material is collected, it is prepared into a powder. Weigh 15 g and put it into a briquetting mold with a diameter of 30 mm. The press provides a pressure of 30 MPa and the pressure holding time is 60 s.

[0036] Step 3: Put the green body obtained in Step 2 into an auxiliary heating body for sintering. The sintering method is microwave sintering, the heating frequency is 2450 MHz, and the maximum input power is 8 kW. In the low-temperature stage, it is heated to a stable reflection power at a rate of 60 °C / min, and then the heating rate is maintained at 30 °C / min until 950 °C, and it is kept warm for 30 min, and then slowly cooled to room temperature with the furnace to prepare a novel fluorite-type high-entropy oxide ceramic with the chemical formula (Al 0.2 Ti 0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O 2 .

[0037] Example 3 A preparation method of a novel fluorite-type high-entropy oxide ceramic, comprising the following steps: Step 1: Mix five oxide powders TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Cr2 O 3 The molar ratio of the powders is formulated into a mixed raw material as 0.2:0.1:0.1:0.1:0.1. The purity specifications of the 5 kinds of oxide powders used are that the diameters of the powder raw materials are all 1 μm; the average particle size of the mixed powder after ball milling is 0.1 μm.

[0038] Step 2: Put the mixed raw material obtained in Step 1 into a drying oven. The temperature of the drying oven is 100 °C and the drying time is 24 h. The sieve mesh is 100-mesh sieve. After collecting the dried material, it is prepared into a powder. Weigh 40 g and put it into a briquetting mold. The diameter of the mold is 60 mm. The press provides a pressure of 30 MPa and the pressure holding time is 60 s.

[0039] Step 3: Put the green body obtained in Step 2 into an auxiliary heating body for sintering. The sintering method is microwave sintering. The heating frequency is 2450 MHz and the maximum input power is 8 kW. In the low-temperature stage, it rises to a stable reflected power at 40 °C / min, and then maintains the heating rate at 30 °C / min until 950 °C, and keeps the temperature for 30 min. Then it is slowly cooled to room temperature with the furnace to prepare a novel fluorite-type high-entropy oxide ceramic with the chemical formula (Al 0.2 Ti 0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O 2 ).

[0040] Example 4 A preparation method of a novel fluorite-type high-entropy oxide ceramic, comprising the following steps: Step 1: Mix five kinds of oxide powders TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Cr 2 O 3 into a mixed raw material according to a molar ratio of 0.2:0.1:0.1:0.1:0.1. The purity specifications of the 5 kinds of oxide powders used are that the diameters of the powder raw materials are all 2.5 μm; the average particle size of the mixed powder after ball milling is 0.8 μm.

[0041] Step 2: Put the mixed raw material obtained in Step 1 into a drying oven. The temperature of the drying oven is 85 °C and the drying time is 24 h. The sieve mesh is 100-mesh sieve. After collecting the dried material, it is prepared into a powder. Weigh 40 g and put it into a briquetting mold. The diameter of the mold is 60 mm. The press provides a pressure of 30 MPa and the pressure holding time is 60 s.

[0042] Step 3: Put the green body obtained in Step 2 into the auxiliary heating body for sintering. The sintering method is microwave sintering, the heating frequency is 2450 MHz, the maximum input power is 8 kW. In the low-temperature stage, heat at 60 °C / min until the reflected power is stable, then maintain the heating rate at 30 °C / min until 950 °C, hold for 30 min, and then slowly cool with the furnace to room temperature to prepare a novel fluorite-type high-entropy oxide ceramic with the chemical formula (Al 0.2 Ti 0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O 2 .

[0043] Example 5 A preparation method of a novel fluorite-type high-entropy oxide ceramic, comprising the following steps: Step 1: Prepare a mixed raw material by mixing five oxide powders TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Cr 2 O 3 in a molar ratio of 0.2:0.1:0.1:0.1:0.1. The purity specifications of the 5 kinds of oxide powders used are that the diameter of the powder raw materials is 1.5 μm; the average particle size of the mixed powder after ball milling is 0.3 μm;

[0044] Step 2: Put the mixed raw material obtained in Step 1 into a drying oven. The temperature of the drying oven is 95 °C and the drying time is 24 h. The sieve mesh is 100-mesh sieve. After collecting the dried material, prepare it into a powder. Weigh 15 g and put it into a briquetting mold. The diameter of the mold is 30 mm, the press provides a pressure of 30 MPa, and the pressure holding time is 60 s.

[0045] Step 3: Put the green body obtained in Step 2 into the auxiliary heating body for sintering. The sintering method is microwave sintering, the heating frequency is 2450 MHz, the maximum input power is 8 kW. In the low-temperature stage, heat at 60 °C / min until the reflected power is stable, then maintain the heating rate at 30 °C / min until 1050 °C, hold for 30 min, and then slowly cool with the furnace to room temperature to prepare a novel fluorite-type high-entropy oxide ceramic with the chemical formula (Al 0.2 Ti 0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O 2 .

[0046] Example 6 A preparation method of a novel fluorite-type high-entropy oxide ceramic, comprising the following steps: Step 1: Prepare a mixed raw material by mixing five oxide powders TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Cr 2 O 3 in a molar ratio of 0.2:0.1:0.1:0.1:0.1. The purity specifications of the 5 oxide powders used are that the diameters of the powder raw materials are all 2 μm; the average particle size of the mixed powder after ball milling is 0.5 μm.

[0047] Step 2: Put the mixed raw material obtained in Step 1 into a drying oven. The temperature of the drying oven is 90 °C and the drying time is 24 h. The sieve mesh is a 100-mesh sieve. After collecting the dried material, prepare it into a powder. Weigh 15 g and put it into a briquetting mold with a diameter of 30 mm. The press provides a pressure of 30 MPa and the pressure holding time is 60 s.

[0048] Step 3: Put the green body obtained in Step 2 into an auxiliary heating body for sintering. The sintering method is microwave sintering, the heating frequency is 2450 MHz, and the maximum input power is 8 kW. In the low-temperature stage, heat up to the stable reflection power at a rate of 60 °C / min, and then maintain the heating rate at 30 °C / min until 1150 °C, hold for 30 min, and then slowly cool down to room temperature with the furnace to prepare a novel fluorite-type high-entropy oxide ceramic with the chemical formula (Al 0.2 Ti 0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O 2 .

[0049] Example 7 A preparation method of a novel fluorite-type high-entropy oxide ceramic, comprising the following steps: Step 1: Prepare a mixed raw material by mixing five oxide powders TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Cr 2 O 3 in a molar ratio of 0.2:0.1:0.1:0.1:0.1. The purity specifications of the 5 oxide powders used are that the diameters of the powder raw materials are all 2 μm; the average particle size of the mixed powder after ball milling is 0.51 μm.

[0050] Step 2: Put the mixed raw materials obtained in Step 1 into a drying oven. The temperature of the drying oven is 90 °C, and the drying time is 24 h. The sieve mesh is 100-mesh. After collecting the dried material, it is prepared into a powder. Weigh 15 g and put it into a briquetting mold with a mold diameter of 30 mm. The press provides a pressure of 30 MPa and the pressure holding time is 60 s.

[0051] Step 3: Put the green body obtained in Step 2 into an auxiliary heating body for sintering. The sintering method is microwave sintering, the heating frequency is 2450 MHz, and the maximum input power is 8 kW. In the low-temperature stage, it is heated to the stable reflection power at a rate of 60 °C / min, and then the heating rate is maintained at 30 °C / min until 1250 °C, and it is kept warm for 30 min. After that, it is slowly cooled to room temperature in the furnace to prepare a novel fluorite-type high-entropy oxide ceramic with the chemical formula (Al 0.2 Ti 0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O 2 .

[0052] Example 8 A preparation method of a novel fluorite-type high-entropy oxide ceramic, comprising the following steps: Step 1: Prepare a mixed raw material by mixing five oxide powders TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Cr 2 O 3 in a molar ratio of 0.2:0.1:0.1:0.1:0.1. The purity specifications of the 5 oxide powders used are that the diameters of the powder raw materials are all 2 μm; the average particle size of the mixed powder after ball milling is 0.5 μm.

[0053] Step 2: Put the mixed raw materials obtained in Step 1 into a drying oven. The temperature of the drying oven is 90 °C, and the drying time is 24 h. The sieve mesh is 100-mesh. After collecting the dried material, it is prepared into a powder. Weigh 15 g and put it into a briquetting mold with a mold diameter of 30 mm. The press provides a pressure of 30 MPa and the pressure holding time is 60 s.

[0054] Step 3: Put the green body obtained in Step 2 into an alumina crucible for sintering. The sintering method is muffle furnace non-pressure sintering, the heating rate is 5 °C / min, the sintering temperature is 1350 °C, the heat preservation time is 3 h. After the heat preservation time ends, it is slowly cooled to room temperature in the furnace. After that, it is slowly cooled to room temperature in the furnace to prepare a novel fluorite-type high-entropy oxide ceramic with the chemical formula (Al 0.2 Ti 0.2 Ta0.2 Nb 0.2 Cr 0.2 )O 2 novel fluorite-type high-entropy oxide ceramic

[0055] Example 9 A preparation method of a novel fluorite-type high-entropy oxide ceramic, comprising the following steps: Step 1: Prepare a mixed raw material by mixing five oxide powders TiO 2 , Al 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , Cr 2 O 3 in a molar ratio of 0.2:0.1:0.1:0.1:0.1. The purity specifications of the 5 oxide powders used are that the diameter of the powder raw materials is 2 μm; the average particle size of the mixed powder after ball milling is 0.51 μm.

[0056] Step 2: Put the mixed raw material obtained in Step 1 into a drying oven. The temperature of the drying oven is 90 °C and the drying time is 24 h. The sieve mesh is 100-mesh sieve. After the dried material is collected, it is prepared into a powder. Weigh 15 g and put it into a briquetting mold. The diameter of the mold is 30 mm. The press provides a pressure of 30 MPa and the pressure holding time is 60 s.

[0057] Step 4: Put the green body obtained in Step 3 into an alumina crucible for sintering. The sintering method is non-pressure sintering in a muffle furnace. The heating rate is 5 °C / min, the sintering temperature is 1500 °C, and the holding time is 3 h. After the holding time ends, it is slowly cooled to room temperature with the furnace. Then it is slowly cooled to room temperature with the furnace to prepare a novel fluorite-type high-entropy oxide ceramic with the chemical formula (Al 0.2 Ti 0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O 2 .

[0058] Technical characterization and result discussion: To understand the phase composition and morphological characteristics of the obtained product, X-ray diffraction analyzer (XRD) was used to analyze the phase of the novel fluorite-type high-entropy oxide ceramic prepared in Example 2, and the results are as Figure 1 shown; scanning electron microscope (SEM) was used to detect and analyze the microscopic morphology of the cross-section of the novel fluorite-type high-entropy oxide ceramic prepared in Example 2, and the results are as Figure 2 shown; energy dispersive spectrometer (EDS) was used to detect and analyze the element distribution on the surface of the novel fluorite-type high-entropy oxide ceramic in Example 5.

[0059] Figure 1 The results show that after the raw materials are ball-milled and mixed and then microwave sintered, a new fluorite-type high-entropy oxide ceramic with AlTiTaO as the main phase is formed for the new fluorite-type high-entropy oxide ceramic provided by the present invention.

[0060] Figure 2 The results show that the new fluorite-type high-entropy oxide ceramic prepared by the present invention has a very high relative density, about 97.4%, the measured hardness is 15.4 GPa, and the fracture toughness is 6.45 MPa·m 1 / 2 。

[0061] Figure 3 The results show that the new fluorite-type high-entropy oxide ceramic prepared by the present invention contains elements Al, Ti, Ta, Nb, and Cr, and the distribution of each element is relatively uniform.

[0062] The above-described are only the preferred embodiments of the present invention, and the above specific embodiments are not limitations on the present invention. Within the scope of the technical idea of the present invention, various deformations and modifications can occur. Any retouching, modification, or equivalent replacement made by those of ordinary skill in the art according to the above description shall fall within the scope protected by the present invention.

Claims

1. A method for preparing a novel fluorite-type high entropy oxide ceramic, characterized in that: The following steps are involved: Using TiO2, Al2O3, Nb2O5, Ta2O5 and Cr2O3 as raw materials, according to (Al 0.2 Ti 0.2 Ta 0.2 Nb 0.2 Cr 0.2 ) The molar ratio of each metal element in O2 is weighed, and after being mixed uniformly by wet ball milling, a precursor is prepared; The precursor is dried, dry-milled and sieved, and then cold-pressed to obtain a green embryo; After the green body is sintered, a novel fluorite-type high entropy oxide ceramic with an AlTiTaO single-phase structure is obtained; Wherein, the sintering treatment method is microwave sintering or muffle furnace sintering.

2. The method for preparing the novel fluorite-type high entropy oxide ceramic according to claim 1, characterized in that: The microwave sintering comprises the following steps: The temperature is increased at a rate of 20°C / min to 100°C / min until the reflected power is stable, and then the temperature increase rate is maintained at 20°C / min to 30°C / min until the sintering temperature is 950°C to 1200°C, and the temperature is kept at the sintering temperature for 10min to 60min.

3. The method for preparing the novel fluorite-type high entropy oxide ceramic according to claim 2, characterized in that: The muffle furnace sintering comprises the following steps: The heating rate is 5°C / min, the sintering temperature is 1200°C~1500°C, the holding time is 2h~6h, and after the holding time is over, it is slowly cooled to room temperature with the furnace.

4. The method for preparing the novel fluorite-type high entropy oxide ceramic according to claim 1, characterized in that: The cold pressing treatment is performed at a thickness of 30 mm to 60 mm, a pressure of 30 MPa to 80 MPa, and a holding time of 1 s to 120 s.

5. The method for preparing the novel fluorite-type high entropy oxide ceramic according to claim 1, characterized in that: The average particle size of the raw material is 1 μm to 3 μm, and the average particle size of the precursor is 0.1 μm to 1 μm.

6. A new type of fluorite high entropy oxide ceramic, characterized in that: The novel fluorite-type high-entropy oxide ceramic is prepared by the preparation method of the novel fluorite-type high-entropy oxide ceramic described in any one of claims 1 to 5.

7. The novel fluorite-type high entropy oxide ceramic according to claim 6, characterized in that: The chemical formula of the novel fluorite-type high entropy oxide ceramic is (Al 0.2 Ti 0.2 Ta 0.2 Nb 0.2 Cr 0.2 )O2.

8. The novel fluorite-type high entropy oxide ceramic according to claim 7, characterized in that: The novel fluorite-type high-entropy oxide ceramic has an AlTiTaO single-phase structure.

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