High-entropy ceramic powder as well as preparation method and application thereof

Abstract

The invention relates to the technical field of advanced ceramic materials, in particular to high-entropy ceramic powder and a preparation method and application thereof.The preparation method comprises the following steps that a metal source is dissolved in n-propyl alcohol and mixed to be uniform, and an n-propyl alcohol solution of the metal source is obtained; adding triethylamine into the normal propyl alcohol solution of the metal source to obtain a first mixed solution of the metal source; adding water into the first mixed solution of the metal source to obtain a second mixed solution of the metal source; freeze-drying the second mixed solution of the metal source to obtain a first solid; adding an aqueous solution of glucose into the first solid, carrying out high-temperature reaction, and freeze-drying to obtain a second solid; cracking the second solid in an inert atmosphere to obtain high-entropy ceramic powder; wherein the molecular formula of the high-entropy ceramic powder is MC, and M is a combination of four elements of Nb, Zr, Ta and Ti in an equal molar ratio. The high-entropy ceramic powder disclosed by the invention has the advantages of small agglomeration, low oxygen content, uniform particle size distribution, good particle dispersion and excellent electrochemical performance.

Description

Technical Field

[0001] The present invention relates to the technical field of advanced ceramic materials, and particularly to a high-entropy ceramic powder and its preparation method and application. Background Art

[0002] Traditional ceramic materials have limitations in terms of thermal stability and mechanical properties, and it is difficult to meet the requirements of modern industry for high-performance materials. As a class of multi-component inorganic compounds composed of multiple transition metal elements, high-entropy ceramics exhibit great application potential in aerospace, nuclear energy, and other high-tech fields due to their unique structure and excellent properties, such as high hardness, high elastic modulus, good thermal stability, and mechanical properties.

[0003] By introducing the high-entropy effect, that is, a solid solution formed by mixing multiple elements in equimolar ratio or approximate equimolar ratio, high-entropy ceramics significantly improve the comprehensive properties of the materials. Such ceramics usually have a face-centered cubic or body-centered cubic structure, and can maintain stable mechanical properties and thermal stability in high-temperature environments, providing the possibility for applications under extreme conditions.

[0004] However, the preparation process of high-entropy ceramics is complex, with high requirements for the sintering process, and current research mainly focuses on the preparation of bulk materials. Especially for carbide high-entropy ceramics, there are problems such as agglomeration, uneven particle size distribution, and poor particle dispersion during the preparation of their precursors, which seriously affect the performance and application effect of the final ceramic materials.

[0005] Most of the existing methods for synthesizing carbide high-entropy ceramic precursors use transition metal chlorides and alcohols as raw materials, and introduce a carbon source after complexation with acetylacetone. Although these methods can successfully synthesize most carbide high-entropy ceramic precursors, the resulting precursor powders have serious agglomeration, uneven particle size distribution, and insufficient dispersion between particles, which limit the densification and performance optimization of subsequent ceramic materials.

[0006] Therefore, there is an urgent need to develop a new preparation method that can effectively solve the agglomeration problem of carbide high-entropy ceramic precursors, achieve uniform particle size distribution, and improve particle dispersion, so as to further enhance the comprehensive properties of high-entropy ceramics and promote their wide application in fields such as aerospace and nuclear energy.

[0007] In view of this, the present invention is specifically proposed. Summary of the Invention

[0008] The purpose of the present invention is to provide a high-entropy ceramic powder and its preparation method, which effectively solve the agglomeration problem of carbide high-entropy ceramic precursors, achieve uniform particle size distribution, and improve particle dispersion.

[0009] In the first aspect, the present invention provides a preparation method of a high-entropy ceramic powder, comprising the following steps:

[0010] S1. Dissolve the metal source in n-propanol, mix evenly to obtain an n-propanol solution of the metal source;

[0011] S2. Add triethylamine to the n-propanol solution of the metal source to obtain a first mixed solution of the metal source;

[0012] S3. Add water to the first mixed solution of the metal source to obtain a second mixed solution of the metal source;

[0013] S4. Lyophilize the second mixed solution of the metal source to obtain a first solid;

[0014] S5. Add an aqueous solution of glucose to the first solid, react at high temperature and then lyophilize to obtain a second solid;

[0015] S6. Pyrolyze the second solid under an inert atmosphere to obtain high-entropy ceramic powder;

[0016] Among them, the molecular formula of the high-entropy ceramic powder is MC, where M is a combination of four elements Nb, Zr, Ta, and Ti in equimolar ratio.

[0017] In the preparation method of the present invention, first, the metal source is dissolved in n-propanol. Utilizing the solvent effect of n-propanol and the complexation between the hydroxyl group in n-propanol and metal ions, the metal ions are better dispersed and dissolved to form a solution of metal alkoxide. Then, triethylamine is added to the solution of metal alkoxide. As a basic substance, triethylamine can react with the chloride ions in metal chloride to form intermediate products such as metal alkoxide and ammonium chloride. Further, water is added to promote the hydrolysis of metal alkoxide, forming a precursor of metal hydroxide or oxide, which precipitates out, preparing for the subsequent high-temperature pyrolysis and ceramization processes. At the same time, chloride ions can be effectively removed to avoid the generation of corrosive gases during the pyrolysis process, which may damage the experimental instruments. The second mixed solution of the metal source is lyophilized to remove the water and solvent in the solution, obtaining a dry precursor of metal hydroxide or oxide. Further, an aqueous solution of glucose is added to the dry precursor of metal hydroxide or oxide, and then the reaction is carried out under high-temperature conditions to carbonize glucose and coat it on the surface of metal hydroxide or oxide particles, introducing a carbon source to prepare for the formation of carbon-based composite ceramic powder during the subsequent pyrolysis process. Finally, the second solid is pyrolyzed under an inert atmosphere to cause a chemical reaction between the metal hydroxide or oxide and the carbon source, removing organic groups and forming a stable high-entropy ceramic phase.

[0018] Among them, the present invention uses a two-step freeze-drying method to prepare high-entropy ceramic powders. The prepared high-entropy ceramic powder particles have good dispersibility and a more uniform particle size distribution. This may be because the two-step freeze-drying avoids the deformation or rupture of particles due to thermal stress during the high-temperature drying process, and can better maintain the original morphology and structure of the particles. The interaction between particles is weak, and agglomeration is not likely to occur, thus obtaining a powder with a uniform particle size distribution and good particle dispersion. Therefore, compared with the traditional PDC (polymer-derived ceramic) route, the high-entropy ceramic powder prepared by the present invention has a unique high-entropy effect, effectively solves the problem of agglomeration of carbide high-entropy ceramic precursors, realizes a uniform particle size distribution, and improves particle dispersibility.

[0019] The molecular formula of the finally prepared high-entropy ceramic powder of the present invention is (Ta 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C or (Ta 0.25 Nb 0.25 Zr 0.25 Nb 0.25 )C.

[0020] Preferably, as the technical solution, the Nb source is NbCl 5 , the Zr source is ZrCl 4 , C 12 H 28 O 4 Zr or ZrOCl 2 ·8H 2 O, and any one of them, the Ta source is TaCl 5 , the Ti source is TiCl 4 , C 16 H 36 O 4 Ti or C 8 H 20 O 4 Ti.

[0021] Preferably, as the technical solution, in step S1, the molar ratio of n-propanol to the total metal source is (35-70):1.

[0022] Preferably, as the technical solution, in step S2, the molar ratio of triethylamine to the chloride ions in the metal source is 1:1.

[0023] Preferably, as the technical solution, in step S3, in the second mixed solution of the metal source, the molar ratio of n-propanol to water is 1:(4-6), and preferably 1:5.

[0024] Preferably in this technical solution, in step S4, the molar ratio of carbon in glucose to the total metal source is (1-2):1.

[0025] Preferably in this technical solution, in step S5, an aqueous solution of glucose is added to the first solid, and then the reaction is carried out under high-temperature conditions to carbonize the glucose and coat it on the surface of metal hydroxide or oxide particles. The purpose of this step is to introduce a carbon source for forming carbon-based composite ceramic powders during the subsequent pyrolysis process. Compared with the traditional PDC (polymer-derived ceramic) route, the present invention uses glucose as the carbon source, and the amount of carbon introduced is more controllable and it is not easy to cause carbon precipitation and other situations in the subsequent sintering process. Specifically, during the high-temperature reaction, the temperature is preferably 160-180°C and the time is preferably 6-10 h.

[0026] Preferably in this technical solution, in step S6, through high-temperature pyrolysis, the metal hydroxide or oxide reacts with the carbon source to form a stable high-entropy ceramic phase. During the high-temperature pyrolysis process, if the pyrolysis temperature is too low, it will be difficult to form single-phase ceramic powders, and if the pyrolysis temperature is too high, it will cause waste of resources. Research shows that during pyrolysis, controlling the temperature at 1800-2000°C and the time at 1-2 h can obtain high-entropy ceramic powders with excellent material and chemical properties.

[0027] Preferably in this technical solution, in step S6, the use of an inert atmosphere can avoid oxidation of the material and introduction of impurities at high temperatures. The inert atmosphere of the present invention includes any one of nitrogen atmosphere, argon atmosphere and helium atmosphere.

[0028] In the second aspect, the present invention also discloses the high-entropy ceramic powders prepared according to the above preparation method, which should also belong to the protection scope of the present invention. The molecular formula of the high-entropy ceramic powders is (Ta 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C or (Ta 0.25 Nb 0.25 Zr 0.25 Nb 0.25 )C.

[0029] In the third aspect, the present invention also discloses the application of the above high-entropy ceramic powders, specifically referring to the application of the high-entropy ceramic powders in the aerospace or energy fields.

[0030] The ultrafine (Ta 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C and (Ta 0.25 Nb 0.25 Zr 0.25 Nb0.25 ) The C high-entropy ceramic powder has small agglomeration, low oxygen content, uniform particle size distribution, good particle dispersion, and excellent electrochemical properties, which makes the high-entropy ceramics prepared therefrom have important application prospects in the fields of aerospace, nuclear energy, etc.

[0031] The preparation method of the high-entropy ceramic powder of the present invention has at least the following beneficial effects:

[0032] 1. In the preparation method of the high-entropy ceramic powder of the present invention, first, the metal source is dissolved in n-propanol. By using the solvent effect of n-propanol and the complexation of hydroxyl groups in n-propanol with metal ions, the metal ions are better dispersed and dissolved to form a solution of metal alkoxide; then triethylamine is added to the solution of metal alkoxide. As a basic substance, triethylamine can react with the chloride ions in the metal chloride to form intermediate products such as metal alkoxide and ammonium chloride. Further, water is added to promote the hydrolysis of the metal alkoxide to form a precursor of metal hydroxide or oxide, which precipitates out in the form of a precipitate, preparing for the subsequent high-temperature pyrolysis and ceramization processes. At the same time, chloride ions can be effectively removed to avoid the generation of corrosive gases during the pyrolysis process, which may damage the experimental instruments; the second mixed solution of the metal source is freeze-dried to remove the water and solvent in the solution, obtaining a dry precursor of metal hydroxide or oxide; further, an aqueous glucose solution is added to the dry precursor of metal hydroxide or oxide, and then the reaction is carried out under high-temperature conditions to carbonize the glucose and coat it on the surface of the metal hydroxide or oxide particles, introducing a carbon source to prepare for the formation of carbon-based composite ceramic powder during the subsequent pyrolysis process; finally, the second solid is pyrolyzed under an inert atmosphere to cause a chemical reaction between the metal hydroxide or oxide and the carbon source, removing organic groups and forming a stable high-entropy ceramic phase. Compared with the traditional PDC (polymer-derived ceramic) route, the high-entropy ceramic powder prepared by the present invention has a unique high-entropy effect, effectively solves the problem of agglomeration of carbide high-entropy ceramic precursors, realizes uniform particle size distribution, and improves particle dispersion;

[0033] 2. The preparation method of the high-entropy ceramic powder of the present invention has the advantages of simple equipment required, easy availability of raw materials, low preparation temperature, low energy consumption, ability to obtain a series of composite ceramic powders, and high powder purity. Description of the Drawings

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 XRD pattern of the high-entropy ceramic powder prepared in Examples 1-2 of the present invention;

[0036] Figure 2 SEM photograph of the high-entropy ceramic powder prepared in Examples 1-2 of the present invention;

[0037] Figure 3 XRD pattern of the high-entropy ceramic powder prepared in the comparative example of the present invention;

[0038] Figure 4 SEM photograph of the high-entropy ceramic powder prepared in the comparative example of the present invention. Detailed implementation manners

[0039] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0040] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0041] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0042] Example 1

[0043] In this example, the preparation method of the ultrafine (Ta 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C high-entropy ceramic powder includes the following steps:

[0044] S1. Weigh 0.01 mol of TiCl 4 , 0.01 mol of NbCl 5 , 0.01 mol of ZrCl 4 , 0.01 mol of TaCl 5 , dissolve them in a n-propanol solution, mix evenly, and obtain a n-propanol solution of the metal source;

[0045] S2. Add 0.18 mol of triethylamine to the n-propanol solution of the metal source to obtain the first mixed solution of the metal source;

[0046] S3. Add 0.04 mol of water to the first mixed solution of the metal source to obtain the second mixed solution of the metal source.

[0047] S4. Lyophilize the second mixed solution of the metal source to obtain the first solid;

[0048] S5. Add an aqueous solution containing 0.0067 mol of glucose to the first solid, and keep it at a high temperature of 160 - 180 °C for 6 - 10 h to obtain the second solid.

[0049] S6. Place the second solid obtained in step S5 in an inert atmosphere and pyrolyze it at 1800 - 2000 °C for 1 - 2 h to obtain ultrafine (Ta 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C high-entropy ceramic powder. Its XRD pattern is as Figure 1 shown.

[0050] Example 2

[0051] In this example, the preparation method of ultrafine ((Ta 0.25 Nb 0.25 Zr 0.25 Nb 0.25 )C ceramic powder includes the following steps:

[0052] S1. Weigh 0.02 mol of NbCl 5 , 0.01 mol of ZrCl 4 , 0.01 mol of TaCl 5 , dissolve them in the n-propanol solution, mix them evenly to obtain the n-propanol solution of the metal source;

[0053] S2. Add 0.19 mol of triethylamine to the n-propanol solution of the metal source to obtain the first mixed solution of the metal source;

[0054] S3. Add 0.04 mol of water to the first mixed solution of the metal source to obtain the second mixed solution of the metal source;

[0055] S4. Lyophilize the second mixed solution of the metal source to obtain the first solid;

[0056] S5. Add an n-propanol solution containing 0.0067 mol of glucose to the first solid, and keep it at a high temperature of 160 - 180 °C for 6 - 10 h to obtain the second solid.

[0057] S6. Place the second solid obtained in step S5 under an inert atmosphere and pyrolyze it at 1800 - 2000 °C for 1 - 2 h to obtain ultrafine (Ta 0.25 Nb 0.25 Zr 0.25 Nb 0.25 )C high - entropy ceramic powder. Its XRD pattern is as shown in Figure 1 shown.

[0058] Example 3

[0059] In this example, the preparation method of ultrafine (Ta 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C high - entropy ceramic powder includes the following steps:

[0060] S1. Weigh 0.01 mol of TiCl 4 , 0.01 mol of NbCl 5 , 0.01 mol of ZrCl 4 , 0.01 mol of TaCl 5 , dissolve them in a n - propanol solution, mix evenly to obtain a n - propanol solution of the metal source;

[0061] S2. Add 0.18 mol of triethylamine to the n - propanol solution of the metal source to obtain a first mixed solution of the metal source;

[0062] S3. Add 0.05 mol of water to the first mixed solution of the metal source to obtain a second mixed solution of the metal source

[0063] S4. Freeze - dry the second mixed solution of the metal source to obtain a first solid;

[0064] S5. Add an aqueous solution containing 0.013 mol of glucose to the first solid, and keep it at a high temperature of 160 - 180 °C for 6 - 10 h to obtain a second solid.

[0065] S6. Place the second solid obtained in step S5 under an inert atmosphere and pyrolyze it at 1800 - 2000 °C for 1 - 2 h to obtain ultrafine (Ta 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C high - entropy ceramic powder.

[0066] Example 4

[0067] In this example, the preparation method of ultrafine ((Ta 0.25 Nb 0.25 Zr 0.25 Nb 0.25 )C ceramic powder includes the following steps:

[0068] S1. Weigh 0.02 mol of NbCl 5 , 0.01 mol of ZrCl 4 , 0.01 mol of TaCl 5 , dissolve them in a n-propanol solution, mix well, and obtain a n-propanol solution of the metal source;

[0069] S2. Add 0.19 mol of triethylamine to the n-propanol solution of the metal source to obtain a first mixed solution of the metal source;

[0070] S3. Add 0.04 mol of water to the first mixed solution of the metal source to obtain a second mixed solution of the metal source;

[0071] S4. Lyophilize the second mixed solution of the metal source to obtain a first solid;

[0072] S5. Add a n-propanol solution containing 0.013 mol of glucose to the first solid, keep it at a high temperature of 160 - 180 °C for 6 - 10 h to obtain a second solid.

[0073] S6. Place the second solid obtained in step S5 in an inert atmosphere and pyrolyze it at 1800 - 2000 °C for 1 - 2 h to obtain ultrafine (Ta 0.25 Nb 0.25 Zr 0.25 Nb 0.25 )C high-entropy ceramic powder.

[0074] Control example

[0075] In this control example, the preparation method of ultrafine (Ta 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C ceramic powder includes the following steps:

[0076] S1. Weigh 0.01 mol of TiCl 4 , 0.01 mol of NbCl 5 , 0.01 mol of ZrCl 4 , 0.01 mol of TaCl 5 , dissolve them in a n-propanol solution, mix well, and obtain a mixed solution A;

[0077] S2. Add 0.18 mol of triethylamine to the mixed solution A, filter it, and obtain a mixed solution B;

[0078] S3. Add 0.04 mol of acetylacetone to the mixed solution B, filter it, and obtain a mixed solution C;

[0079] S4. Add 0.04 mol of water and 0.06 mol of phenolic resin to the mixed solution C, and after filtration, obtain the mixed solution D;

[0080] S5. Rotavaporize, dry, and grind the mixed solution D obtained in step S4 to obtain the solid A;

[0081] S6. Place the solid A obtained in S5 in an inert atmosphere and pyrolyze it at 1800 - 2000 °C for 1 - 2 h to obtain (Ta 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C high - entropy ceramic powder.

[0082] It can be seen from Figures 1-4 that in Examples 1 - 2 of the present invention and the PDC route of the comparative example, single - phase high - entropy ceramic powder can be successfully prepared, and the obtained high - entropy ceramic powder has high purity and low oxygen content. However, compared with the method of the present invention, the comparative example has the phenomena of agglomeration, uneven particle size distribution, and poor particle dispersion.

[0083] In summary, the high - entropy ceramic powder prepared by the present invention has a unique high - entropy effect, effectively solves the problem of agglomeration of the carbide high - entropy ceramic precursor, realizes uniform particle size distribution, and improves particle dispersion.

[0084] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing high entropy ceramic powder, characterized in that: The following steps are involved: S1, dissolving the metal source in n-propanol, mixing evenly, to obtain an n-propanol solution of the metal source; S2, adding triethylamine to the n-propanol solution of the metal source to obtain a first mixed solution of the metal source; S3, adding water to the first mixed solution of the metal source to obtain a second mixed solution of the metal source; S4, freeze-drying the second mixed solution of the metal source to obtain a first solid; S5, adding an aqueous solution of glucose to the first solid, reacting at high temperature and freeze-drying to obtain a second solid; S6, placing the second solid under an inert atmosphere for cracking to obtain a high entropy ceramic powder; The molecular formula of the high entropy ceramic powder is MC, wherein M is a combination of four elements of Nb, Zr, Ta, Ti and Nb in equal molar ratios.

2. The preparation method according to claim 1, characterized in that: The Nb source is NbCl5, and the Zr source is ZrCl4, C 12 H 28 O4Zr or ZrOCl2·8H2O, Ta source is TaCl5, Ti source is TiCl4, C 16 H 36 O4Ti or C8H 20 Any one of O4Ti, the Nb source is NbCl5.

3. The preparation method according to claim 1, characterized in that: In step S1, the total molar ratio of n-propanol to the metal source is (35-70):

1.

4. The preparation method according to claim 1, characterized in that: In step S2, the molar ratio of triethylamine to chloride ions in the metal source is 1:

1.

5. The preparation method according to claim 1, characterized in that: In step S3, in the second mixed solution of the metal source, the molar ratio of n-propanol to water is 1:(4-6).

6. The preparation method according to claim 1, characterized in that: In step S4, the total molar ratio of carbon in glucose to the total molar ratio of the metal source is (1-2):

1.

7. The preparation method according to claim 1, characterized in that: In step S5, during the high temperature reaction, the temperature is controlled to be 160-180° C. and the time is 6-10 hours.

8. The preparation method according to claim 1, characterized in that: In step S6, during the cracking, the temperature is controlled to be 1800-2000° C. and the time is 1-2 hours.

9. A high entropy ceramic powder, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 8, the molecular formula of the high entropy ceramic powder is (Ta 0.25 Nb 0.25 Zr 0.25 Ti 0.25 )C or (Ta 0.25 Nb 0.25 Zr 0.25 Nb 0.25 )C.

10. Use of the high entropy ceramic powder prepared by the preparation method according to any one of claims 1 to 8 or the high entropy ceramic powder according to claim 9, characterized in that: The high entropy ceramic powder is used in the fields of aerospace or energy.

Images