High-entropy ceramic bulk and method of making the same

Abstract

This application relates to the field of ultra-high temperature ceramic composite materials technology, and discloses a high-entropy ceramic bulk and its preparation method. The preparation method includes: preparing amorphous ceramic powder: ball milling a mixture of multiple single-component carbide powders to obtain amorphous ceramic powder with uniform composition; preparing carbon-containing ceramic green body: mixing amorphous ceramic powder with a carbon source to obtain carbon-containing mixed powder, and preparing a carbon-containing ceramic green body for reaction infiltration by pressing and slurry settling processes; forming high-entropy ceramic in situ by melt infiltration: placing the carbon-containing ceramic green body in a graphite crucible or graphite box and embedding it with a transition metal or its alloy; after infiltration, polishing the residual alloy on the surface to obtain a dense high-entropy ceramic bulk.

Description

Technical Field

[0001] This application relates to the field of ultra-high temperature ceramic composite materials technology, specifically to a high-entropy ceramic bulk and its preparation method. Background Technology

[0002] Currently, hypersonic vehicles represent the pinnacle of future aerospace technology, and thermal protection systems and materials are among the most critical technologies in their development. Components such as the leading edge of the wing and the hot end of the engine in hypersonic vehicles need to withstand extremely high temperatures, placing stringent requirements on their thermal protection materials. Existing single-component and multi-component ultra-high temperature ceramics have relatively low melting points, limiting the development of thermal protection materials for hypersonic vehicles.

[0003] In this regard, high-entropy ceramics, as a new type of single-phase solid solution ceramic containing multiple components, have higher strength, modulus, hardness, melting point and better corrosion resistance than traditional ceramics, as well as excellent resistance to oxidation and ablation. Therefore, they have great development potential in the field of ultra-high temperature ceramics and their composite materials.

[0004] In the process of implementing the embodiments of this disclosure, at least the following problems were found in the related art:

[0005] Reference 1, “Phase stability, mechanical properties and melting points of high-entropy quaternary metal carbides from first-principles,” uses thermodynamic calculations to show that high-entropy carbides have melting points exceeding 4000℃ and exhibit good stability, thus making them promising candidates for ablation-resistant materials.

[0006] Chinese invention patent CN108911751A discloses a ZrHfTaNbTiC ultra-high temperature high-entropy ceramic material and its preparation method. This method uses micron-sized powders of ZrC, HfC, TaC, NbC, and TiC as raw materials and successfully prepares single-phase ZrHfTaNbTiC high-entropy ceramics through hot-pressing sintering technology. This method features low sintering temperatures (1700–1900℃) and low required external pressure (20–30 MPa). However, it requires steps such as rotary evaporation of the ball-milled powder and cyclic pressurization and densification of the powder in a graphite mold, resulting in complex equipment, high costs, and limitations on the size and shape of the ceramics.

[0007] Reference 2, "Gradient microstructure development and grain growth inhibition in high entropy carbide ceramics prepared by reactive spark plasma sintering," describes the preparation of high entropy carbide ceramics (Ti) using metal oxides and graphite as raw materials via reactive spark plasma sintering. 0.2 Hf 0.2 Nb 0.2 Ta 0.2 W 0.2 The oxide carbothermal reduction method has a short preparation cycle and small grain size. However, it inevitably results in the presence of oxide and carbon residues, uneven element distribution, and lower density of the prepared ceramics.

[0008] Document 3 "Synthesis, mechanical, and thermophysical properties of high-entropy(Zr, Ti, Nb, Ta, Hf)C 0.8 "Ceramic" was prepared by introducing carbon vacancies to lower the sintering temperature using spark plasma sintering (SPS). (Zr, Ti, Nb, Ta, Hf)C was then produced. 0.8 The sintering temperature can be reduced to 1900℃. However, this method requires a spark plasma sintering furnace, which is expensive and imposes significant limitations on sample size and shape. Summary of the Invention

[0009] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0010] This disclosure provides a high-entropy ceramic bulk and its preparation method. The method uses carbide powder as raw material, obtains a carbon-containing ceramic green body by slurry sedimentation or pressing, and finally uses a reaction melting process to form a high-entropy carbide ceramic in situ from the carbon-containing ceramic green body. This method solves the problems of complex process, high equipment requirements and low density of ceramic bulk in existing high-entropy ceramic preparation technologies.

[0011] In some embodiments, the high-entropy ceramic bulk material is a face-centered cubic single-phase ceramic with the molecular formula (aMe1bMe2cMe3dMe4eMe5)C or (fMe1gMe2hMe3iMe4)C, wherein Me includes Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si elements, with each element having an atomic percentage between 5% and 35%, and a+b+c+d+e=f+g+h+i=1.

[0012] In some embodiments, the method for preparing the high-entropy ceramic bulk includes:

[0013] Preparation of amorphous ceramic powder: A mixture of various single-component carbide powders is ball-milled to obtain amorphous ceramic powder with uniform composition;

[0014] Preparation of carbon-containing ceramic green bodies: Amorphous ceramic powder is mixed with a carbon source to obtain carbon-containing mixed powder. The mixed powder is then processed into carbon-containing ceramic green bodies suitable for reaction melting and infiltration through a pressing process and a slurry settling process.

[0015] In-situ formation of high-entropy ceramics by melt infiltration: carbon-containing ceramic blanks are placed in graphite crucibles or graphite boxes and embedded using transition metals or their alloys.

[0016] The heating rate during the melting and infiltration process is 10–50℃ / min, the holding temperature is 20–300℃ above the melting point of the metal or alloy, the holding time is 10–120 min, and the cooling rate is 5–10℃ / min.

[0017] After melting and infiltration, the residual alloy on the surface is polished to obtain a dense high-entropy ceramic block.

[0018] Optionally, the mixed powder of multiple single-component carbide ceramics includes any 2 to 5 combinations of transition metal carbides including TiC, ZrC, HfC, VC, NbC or TaC and SiC, wherein the molar ratio of each carbide can be adjusted; the ball milling speed is 300 r / min, and the ball milling time is 10 to 30 h.

[0019] Optionally, the carbon source includes one or more of graphite, carbon black, and resin carbon.

[0020] Optionally, the tableting process uses a compression pressure of 20 MPa and a holding time of 5 min.

[0021] Optionally, the slurry settling process includes:

[0022] Amorphous ceramic powder is mixed with a carbon source to obtain carbon-containing mixed powder;

[0023] Slurry preparation: using carbon-containing mixed powder as solute, using one or more combinations of water, anhydrous ethanol, toluene or xylene as solvent, and using polyethyleneimine or sodium carboxymethyl cellulose as dispersant;

[0024] The slurry is poured into a mold of a specific shape, left to stand for 10 to 60 minutes, and then placed in an oven at 60 to 120°C for 3 to 5 hours. After demolding, a carbon-containing ceramic green body suitable for reaction melting and infiltration is obtained.

[0025] Optionally, the mass ratio of the mixed powder to the solvent is 1:1 to 3:1, the dispersant accounts for 1 to 2% of the total mass of the slurry, the magnetic stirring time after the slurry is prepared is 3 to 24 hours, and ultrasonic dispersion is performed once during the magnetic stirring, with an ultrasonic dispersion time of 10 to 30 minutes.

[0026] Optionally, the mold may be made of glass, resin, or silicone.

[0027] Optionally, the transition metal is an element of Ti, Zr, Hf, V, Nb, Ta, or Cr, and the transition metal alloy is an alloy composed of 2 to 5 elements selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W. The transition metal or its alloy reacts with the carbon source in the billet to generate corresponding transition metal carbides that fill the pores in the billet, while the alloy melt acts as an element diffusion medium.

[0028] Optionally, the infiltration atmosphere during the infiltration process is a vacuum, argon, or nitrogen.

[0029] This disclosure provides a method for preparing a high-entropy ceramic bulk and an in-situ synthesis method for high-entropy ceramic bulk through reaction melting and infiltration. The carbon-containing preform is prepared by a pressing process and a slurry settling process, which can achieve the following technical effects:

[0030] In-situ synthesis of high-entropy ceramics via reactive infiltration yields bulk ceramics with high density, uniform elemental distribution, no significant segregation, and low oxygen content. Furthermore, this method is simple and low-cost, making it suitable for preparing ceramic bulks with complex shapes.

[0031] The beneficial technical effects of this application specifically include:

[0032] (1) High-entropy carbide ceramics are generated in situ from single-component carbide powder by reaction melting and infiltration. The reaction can be carried out in tube furnace or sintering furnace. Compared with hot pressing sintering and spark plasma sintering, the cost is lower and the sample size is not limited by graphite mold.

[0033] (2) This method has simple steps and a short preparation cycle, and can obtain relatively dense high-entropy ceramics. The porosity of the prepared ceramic block is 1.22% to 3.70%.

[0034] (3) The high-entropy ceramics prepared by this method have uniform element distribution, low oxygen content, and the same composition between each grain, with no obvious segregation phenomenon.

[0035] (4) Using the slurry settling method to prepare carbon-containing ceramic blanks can significantly improve the penetration behavior of the melt, further improve the element distribution inside the ceramic after melting and infiltration, help to obtain high-entropy ceramics with uniform element distribution, and can prepare ceramic blocks with complex shapes.

[0036] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0037] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein:

[0038] Figure 1 This is a schematic flowchart of a method for preparing a high-entropy ceramic bulk according to an embodiment of this disclosure;

[0039] Figure 2 This is a schematic flowchart of another method for preparing a high-entropy ceramic bulk provided in this embodiment;

[0040] Figure 3 This is an X-ray diffraction (XRD) pattern of (TiZrHfNbTa)C high-entropy ceramic prepared by reactive melt infiltration according to an embodiment of this disclosure;

[0041] Figure 4 This is a cross-sectional scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) result of a reaction melt infiltration preparation of (TiZrHfNbTa)C high-entropy ceramics provided in this embodiment of the disclosure;

[0042] Figure 5 This is a cross-sectional scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) result image of a (ZrHfNbTa)C high-entropy ceramic prepared by reactive melt infiltration according to an embodiment of this disclosure;

[0043] Figure 6 This is a transmission electron microscope (TEM) image of a (TiZrHfNbTa)C high-entropy ceramic prepared by reactive melt infiltration according to an embodiment of this disclosure. Detailed Implementation

[0044] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0045] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0046] Unless otherwise stated, the term "multiple" means two or more.

[0047] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0048] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0049] The term "correspondence" can refer to an association or binding relationship. The correspondence between A and B means that there is an association or binding relationship between A and B.

[0050] This disclosure provides a high-entropy ceramic bulk material, which is a face-centered cubic single-phase ceramic with the molecular formula (aMe1bMe2cMe3dMe4eMe5)C or (fMe1gMe2hMe3iMe4)C, wherein Me includes transition metal elements such as Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, and Si, with the atomic percentage of each element between 5% and 35%, and a+b+c+d+e=f+g+h+i=1.

[0051] Combination Figures 1 to 6 As shown, this disclosure provides a method for preparing carbon-containing ceramic green bodies using carbide powder as raw material, through slurry sedimentation or pressing, and finally using a reactive melting process to form high-entropy carbide ceramics in situ from the carbon-containing ceramic green bodies, comprising:

[0052] Step 101: Preparation of amorphous ceramic powder: The mixed powder of various single-component carbides is ball-milled to obtain amorphous ceramic powder with uniform composition.

[0053] In the embodiments of this application, a combination of any 2 to 5 transition metal carbides such as TiC, ZrC, HfC, VC, NbC, and TaC, and SiC is mixed, with the molar ratio of each carbide adjustable within a certain range. The mixed powder is then subjected to planetary ball milling at a speed of 200–500 r / min for 10–30 h to obtain a uniformly composed amorphous ceramic powder.

[0054] Step 102: Preparation of carbon-containing ceramic green body: Amorphous ceramic powder is mixed with carbon source to obtain carbon-containing mixed powder. The mixed powder is processed into carbon-containing ceramic green body for reaction melting and infiltration through pressing process and slurry sedimentation process.

[0055] Optionally, in step 102, the carbon source of the carbon-containing mixed powder can be one or more of graphite, carbon black, and resin carbon.

[0056] Optionally, in step 102, the compression pressure of the tableting process can be 20 MPa, and the holding time can be 5 min.

[0057] In the embodiments of this application, combined with Figure 2 As shown, the slurry settling process in step 102 specifically includes:

[0058] Step 201: Mix amorphous ceramic powder with a carbon source to obtain carbon-containing mixed powder.

[0059] Step 202: Prepare slurry: Use carbon-containing mixed powder as solute, one or more combinations of water, anhydrous ethanol, toluene or xylene as solvent, and polyethyleneimine or sodium carboxymethyl cellulose as dispersant.

[0060] Step 203: Pour the slurry into a mold of a specific shape, let it stand for 10 to 60 minutes, and then place it in an oven at 60 to 120°C for 3 to 5 hours. After demolding, a carbon-containing ceramic green body suitable for reaction melting and infiltration is obtained.

[0061] The mass ratio of the mixed powder to the solvent can be 1:1 to 3:1, the dispersant accounts for 1 to 2% of the total mass of the slurry, the magnetic stirring time after the slurry is prepared can be 3 to 24 hours, and ultrasonic dispersion is performed once during the magnetic stirring, the ultrasonic dispersion time can be 10 to 30 minutes. The mold material can be glass, resin or silicone.

[0062] Step 103: In-situ formation of high-entropy ceramics by melt infiltration: The carbon-containing ceramic blank is placed in a graphite crucible or graphite box and embedded using a transition metal or its alloy.

[0063] In the embodiments of this application, the heating rate during the melting and infiltration process can be 10-50°C / min, the holding temperature can be 20-300°C above the melting point of the metal or alloy, the holding time can be 10-120 min, and the cooling rate can be 5-10°C / min.

[0064] Step 104: After melting and infiltration, polish the residual alloy on the surface to obtain a dense high-entropy ceramic block.

[0065] Optionally, the transition metal or its alloy in step 103 can be elemental Ti, Zr, Hf, V, Nb, Ta, Cr, or an alloy composed of 2 to 5 elements selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W. The role of the transition metal or its alloy is to react with the carbon source in the billet to generate corresponding transition metal carbides that fill the pores within the billet. Simultaneously, the alloy melt acts as an element diffusion medium, accelerating the solid solution of the transition metal and carbon, lowering the melting and infiltration temperature, and shortening the heat treatment time.

[0066] Using the high-entropy ceramic bulk and its preparation method provided in this disclosure, high-entropy ceramics can be synthesized in situ through reactive melting and infiltration. The prepared ceramic bulk has high density, uniform element distribution inside the ceramic, no obvious segregation, and low oxygen content. At the same time, the method is simple to operate, low in cost, and can prepare ceramic bulk with complex shapes.

[0067] The above content will be specifically illustrated below through the following examples and comparative examples:

[0068] Example 1

[0069] Step 1: Preparation of amorphous ceramic powder: TiC, ZrC, HfC, NbC and TaC are mixed in equimolar ratio, and the mixed powder is subjected to planetary ball milling to obtain amorphous ceramic powder with uniform composition.

[0070] Step 2: Preparation of carbon-containing ceramic green body: Amorphous ceramic powder is placed in a mortar, and an appropriate amount of graphite is added. The molar ratio of the mixed powder to graphite is (TiC+ZrC+HfC+NbC+TaC):C = 5:3. The mixture is ground evenly to obtain carbon-containing ceramic powder. Then, the carbon-containing ceramic powder is placed in a Ф12.7mm pressing mold, and the pressing pressure is 20MPa for 5min to obtain the carbon-containing ceramic green body.

[0071] Step 3: In-situ formation of high-entropy ceramics using melt infiltration method.

[0072] The carbon-containing ceramic preform prepared in step 2 was placed in a graphite box and embedded with a Zr-48wt%Ti alloy. The graphite box was placed in a sintering furnace, and the melting and infiltration process was carried out under vacuum. The heating rate was 10–50 °C / min, the holding temperature was 1750 °C, the holding time was 30 min, and the cooling rate was 5–10 °C / min. The residual alloy on the sample surface was polished to obtain a dense, high-entropy ceramic bulk with an open porosity of 1.22%.

[0073] Example 2

[0074] Step 1: Preparation of amorphous ceramic powder: TiC, ZrC, HfC, NbC and TaC are mixed in equimolar ratio, and the mixed powder is subjected to planetary ball milling to obtain amorphous ceramic powder with uniform composition.

[0075] Step 2: Preparation of carbon-containing ceramic green body: Add an appropriate amount of carbon source to the amorphous ceramic powder. The molar ratio of the mixed powder to the carbon source is (TiC+ZrC+HfC+NbC+TaC):C = 5:3. The mass ratio of graphite to carbon black in the carbon source is 1:1. Grind the mixture evenly in a mortar to obtain carbon-containing ceramic powder. Then, place the carbon-containing ceramic powder into a Ф12.7mm pressing mold, press it at a pressure of 20MPa, and hold it for 10min to obtain the carbon-containing ceramic green body.

[0076] Step 3: In-situ formation of high-entropy ceramics using melt infiltration method.

[0077] The carbon-containing ceramic preform prepared in step 2 was placed in a graphite box and embedded with a Zr-48wt% Ti alloy. The graphite box was placed in a sintering furnace, and the melting and infiltration process was carried out under vacuum. The heating rate was 10–50 °C / min, the holding temperature was 1600 °C, the holding time was 60 min, and the cooling rate was 5–10 °C / min. The residual alloy on the sample surface was polished to obtain a dense, high-entropy ceramic bulk with an open porosity of 3.70%.

[0078] Example 3

[0079] Step 1: Preparation of amorphous ceramic powder: TiC, ZrC, HfC, NbC and TaC are mixed in equimolar ratio, and the mixed powder is subjected to planetary ball milling to obtain amorphous ceramic powder with uniform composition.

[0080] Step 2: Preparation of carbon-containing ceramic green body: Add an appropriate amount of graphite to the amorphous ceramic powder, with a molar ratio of (TiC+ZrC+HfC+NbC+TaC):C = 5:3. Prepare a slurry using the above-mentioned carbon-containing ceramic powder as the solute, water as the solvent, and polyethyleneimine as the dispersant. The mass ratio of the mixed powder to the solvent is 1:1, and the dispersant accounts for 1% of the total mass of the slurry. After the slurry is prepared, magnetically stir for 24 hours, and ultrasonically disperse once during the magnetic stirring period for 30 minutes. Pour the above slurry into a mold of a certain shape; the mold material can be glass, resin, silicone, etc. After standing for 60 minutes, place it in an oven at 80℃ for 5 hours. After demolding, a carbon-containing ceramic green body with a certain strength is obtained.

[0081] Step 3: In-situ formation of high-entropy ceramics using melt infiltration method.

[0082] The carbon-containing ceramic preform prepared in step 2 was placed in a graphite box and embedded with a Zr-48wt%Ti alloy. The graphite box was placed in a sintering furnace, and the melting and infiltration process was carried out under vacuum. The heating rate was 10–50 °C / min, the holding temperature was 1750 °C, the holding time was 30 min, and the cooling rate was 5–10 °C / min. The residual alloy on the sample surface was polished to obtain a dense, high-entropy ceramic bulk with an open porosity of 2.48%.

[0083] Example 4

[0084] Step 1: Preparation of amorphous ceramic powder: TiC, ZrC, HfC, NbC and TaC are mixed in equimolar ratio, and the mixed powder is subjected to planetary ball milling to obtain amorphous ceramic powder with uniform composition.

[0085] Step 2: Preparation of carbon-containing ceramic green body: Add an appropriate amount of graphite to the amorphous ceramic powder. The molar ratio of amorphous ceramic powder to graphite is (TiC+ZrC+HfC+NbC+TaC):C = 5:3. Prepare a slurry using the above carbon-containing ceramic powder as the solute, water as the solvent, and polyethyleneimine as the dispersant. The mass ratio of the mixed powder to the solvent is 6:4, and the dispersant accounts for 1% of the total mass of the slurry. After the slurry is prepared, magnetically stir for 24 hours, and ultrasonically disperse once during the magnetic stirring for 30 minutes. Pour the above slurry into a mold of a certain shape. The mold material can be glass, resin, silicone, etc. After standing for 60 minutes, place it in an oven at 80℃ for 5 hours. After demolding, a carbon-containing ceramic green body with a certain strength is obtained.

[0086] Step 3: In-situ formation of high-entropy ceramics using melt infiltration method.

[0087] The carbon-containing ceramic preform prepared in step 2 was placed in a graphite box and embedded with a Zr-48wt% Ti alloy. The graphite box was placed in a sintering furnace, and the melting and infiltration process was carried out under vacuum. The heating rate was 10–50 °C / min, the holding temperature was 1650 °C, the holding time was 30 min, and the cooling rate was 5–10 °C / min. The residual alloy on the sample surface was polished to obtain a dense, high-entropy ceramic bulk with an open porosity of 2.05%.

[0088] Example 5

[0089] Step 1: Preparation of amorphous ceramic powder: ZrC, HfC, NbC and TaC are mixed in equimolar ratio, and the mixed powder is subjected to planetary ball milling to obtain amorphous ceramic powder with uniform composition.

[0090] Step 2: Preparation of carbon-containing ceramic green body: Add an appropriate amount of graphite to the amorphous ceramic powder, with a molar ratio of (ZrC+HfC+NbC+TaC):C = 4:3. Prepare a slurry using the above-mentioned carbon-containing ceramic powder as the solute, water as the solvent, and polyethyleneimine as the dispersant. The mass ratio of the mixed powder to the solvent is 6:4, and the dispersant accounts for 1% of the total mass of the slurry. After the slurry is prepared, magnetically stir for 24 hours, and ultrasonically disperse once during the magnetic stirring period for 30 minutes. Pour the above slurry into a mold of a certain shape; the mold material can be glass, resin, silicone, etc. After standing for 60 minutes, place it in an oven at 80℃ for 5 hours. After demolding, a carbon-containing ceramic green body with a certain strength is obtained.

[0091] Step 3: In-situ formation of high-entropy ceramics using melt infiltration method.

[0092] The carbon-containing ceramic preform prepared in step 2 was placed in a graphite box and embedded with an Hf-49wt% Zr alloy. The graphite box was placed in a sintering furnace, and the melting and infiltration process was carried out under vacuum. The heating rate was 10–50 °C / min, the holding temperature was 2050 °C, the holding time was 30 min, and the cooling rate was 5–10 °C / min. The residual alloy on the sample surface was polished to obtain a dense high-entropy ceramic bulk with an open porosity of 2.19%.

[0093] The foregoing description and accompanying drawings fully illustrate embodiments of this disclosure to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, procedural, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. Moreover, the terminology used in this application is for describing embodiments only and is not intended to limit the claims. As used in the description of embodiments and claims, the singular forms “a,” “an,” and “the” are intended to equally include the plural forms unless the context clearly indicates otherwise. Similarly, the term “and / or” as used in this application means including one or more of the associated listed items and all possible combinations thereof. Additionally, when used in this application, the term "comprise" and its variations "comprises" and / or "comprising" refer to the presence of stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof. Without further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the process, method, or apparatus that includes said element. In this document, each embodiment may focus on the differences from other embodiments, and similar or identical parts between embodiments can be referred to mutually. For methods, products, etc., disclosed in the embodiments, if they correspond to the method section disclosed in the embodiments, the relevant parts can be referred to the description of the method section.

[0094] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the embodiments of this disclosure. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0095] The methods and products (including but not limited to devices and equipment) disclosed in the embodiments herein can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units may be merely a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the shown or discussed units may be through some interfaces, and the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units may be selected to implement this embodiment according to actual needs. Furthermore, the functional units in the embodiments of this disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0096] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than that shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. Each block in a block diagram and / or flowchart, and combinations of blocks in a block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

Claims

1. A method for producing a high-entropy ceramic bulk, characterized by, High-entropy ceramics are single-phase ceramics with a face-centered cubic structure. The molecular formula of high-entropy ceramics is (aMe1bMe2cMe3dMe4eMe5)C or (fMe1gMe2hMe3iMe4)C, where Me includes Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si elements, with the atomic percentage of each element between 5% and 35%, and a+b+c+d+e=f+g+h+i=1; The preparation method includes: Preparation of amorphous ceramic powder: A mixture of multiple single-component carbide powders is ball-milled to obtain amorphous ceramic powder with uniform composition; Preparation of carbon-containing ceramic green body: Amorphous ceramic powder is mixed with a carbon source to obtain carbon-containing mixed powder. The carbon-containing mixed powder is then processed into a carbon-containing ceramic green body suitable for reaction melting and infiltration by a pressing process or a slurry settling process. The pressing process is carried out at a pressing pressure of 20 MPa and a holding time of 5 min. In-situ formation of high-entropy ceramics by melt infiltration: carbon-containing ceramic blanks are placed in graphite crucibles or graphite boxes and embedded using transition metals or their alloys. The heating rate during the melting and infiltration process is 10~50℃ / min, the holding temperature is 20~300℃ above the melting point of the metal or alloy, the holding time is 10~120min, and the cooling rate is 5~10ºC / min. After melting and infiltration, the residual alloy on the surface is polished to obtain a dense high-entropy ceramic block. The slurry settling process includes: Amorphous ceramic powder is mixed with a carbon source to obtain carbon-containing mixed powder; Slurry preparation: using carbon-containing mixed powder as solute, using one or more combinations of water, anhydrous ethanol, toluene or xylene as solvent, and using polyethyleneimine or sodium carboxymethyl cellulose as dispersant; Pour the slurry into a mold of a specific shape, let it stand for 10 to 60 minutes, and then place it in an oven at 60 to 120°C for 3 to 5 hours. After demolding, a carbon-containing ceramic green body that can be reacted and infiltrated is obtained. The mass ratio of the carbon-containing mixed powder to the solvent is 1:1 to 3:1, the dispersant accounts for 1 to 2% of the total mass of the slurry, the magnetic stirring time after the slurry is prepared is 3 to 24 hours, and ultrasonic dispersion is performed once during the magnetic stirring, with an ultrasonic dispersion time of 10 to 30 minutes. The mold is made of glass, resin, or silicone.

2. The preparation method according to claim 1, characterized in that, The mixed powder of multiple single-component carbide ceramics includes any five combinations of transition metal carbides including TiC, ZrC, HfC, VC, NbC or TaC and SiC, wherein the molar ratio of each carbide can be adjusted; the ball milling speed is 300 r / min, and the ball milling time is 10~30 h.

3. The preparation method according to claim 1, characterized in that, The carbon source includes one or more of graphite, carbon black, and resin carbon.

4. The preparation method according to claim 1, characterized in that, The transition metal is an element of Ti, Zr, Hf, V, Nb, Ta, or Cr, and the transition metal alloy is an alloy composed of 2 to 5 elements selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W. The transition metal or its alloy reacts with the carbon source in the billet to generate corresponding transition metal carbides that fill the pores in the billet, while the alloy melt acts as an element diffusion medium.

5. The preparation method according to claim 1, characterized in that, The infiltration atmosphere during the melting process is vacuum, argon, or nitrogen.

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