Tantalum carbide coating and method of making same, tantalum carbide article

Abstract

The application provides a tantalum carbide coating and a preparation method and a tantalum carbide product. The preparation method comprises the following steps: mixing tantalum pentoxide and carbon powder to prepare a mixture; mixing the mixture, ethyl cellulose, lauric acid, terpineol and an acetylacetone metal salt to prepare a slurry; transferring the slurry to the surface of a substrate, and sequentially performing a forming treatment and a heat treatment to prepare the tantalum carbide coating; wherein the mass content of the acetylacetone metal salt is 2% to 9% based on the total mass of the mixture. The preparation method has the advantages that lauric acid and ethyl cellulose are used as film forming agents, terpineol and a specific mass content of acetylacetone metal salt are added at the same time, and the mutual cooperation of the above-mentioned substances can make the prepared tantalum carbide coating have good breaking performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tantalum carbide coating, in particular to a tantalum carbide coating, a preparation method thereof and a tantalum carbide product. BACKGROUND

[0002] Silicon carbide (SiC) single crystal is a kind of semiconductor material, which has wide application prospects in new energy, aerospace and military fields. At present, when preparing silicon carbide single crystal by using physical vapor transport method (PVT), high temperature of 2400℃ or above is usually required, and the raw material needs to have high purity, and the crucible, seed crystal holder and other supplies need to be able to withstand high temperature and not to contaminate the silicon carbide raw material and the silicon carbide crystal. The commonly used crucible, seed crystal holder and other supplies are all graphite materials. At high temperature of 2400℃ or above, SiC powder is easy to volatilize to generate Si and Si2C rich silicon gas, which will react with the graphite substrate and damage the graphite substrate.

[0003] In order to solve the above problems, the traditional technology sets a tantalum carbide coating on the surface of the crucible, seed crystal holder and other supplies, which does not react with silicon carbide, graphite and silicon at high temperature. The coating has good thermal physical matching with graphite, and is an ideal coating material for graphite components required for silicon carbide single crystal growth. Tantalum carbide does not chemically react with carbon powder, silicon powder and silicon carbide at high temperature, which can well protect the graphite substrate and reduce the diffusion of carbon atoms of the graphite substrate at high temperature, thereby ensuring the quality of the SiC single crystal. At the same time, tantalum carbide has excellent high temperature resistance, which can reduce the damage or impurities of the graphite components in the silicon carbide single crystal growth furnace, and provide an excellent growth environment for the growth of silicon carbide single crystal, thereby reducing the pollution of the crystal, improving the quality of the crystal, and prolonging the service life of the graphite components.

[0004] However, the traditional tantalum carbide coating has low density, which is difficult to meet the user's demand, and therefore needs to be further improved. SUMMARY

[0005] Based on this, one or more embodiments of the present application provide a tantalum carbide coating with excellent fracture toughness and high density, a preparation method thereof, and a tantalum carbide product comprising the tantalum carbide coating.

[0006] According to a first aspect of the embodiments of the present application, a preparation method of a tantalum carbide coating is provided, which comprises the following steps:

[0007] Mixing tantalum pentoxide and carbon powder to prepare a mixed material;

[0008] Mixing the mixed material, ethyl cellulose, lauric acid, terpineol and acetylacetone metal salt to prepare a slurry;

[0009] Transferring the slurry to the surface of a substrate, and sequentially performing a forming process and a heat treatment to prepare the tantalum carbide coating;

[0010] Wherein, based on the total mass of the mixture, the mass content of the acetylacetonate metal salt is 2% to 9%.

[0011] In some embodiments, the preparation method satisfies at least one of the following characteristics:

[0012] (1) The molar ratio of the tantalum pentoxide to the carbon powder is 1:(6.95-7);

[0013] (2) The mass ratio of the mixture, the ethyl cellulose and the lauric acid is 10:(2-4):(2-3);

[0014] (3) The substrate includes one or more of a graphite crucible substrate, a carbon fiber substrate, and a graphene substrate;

[0015] (4) The acetylacetonate metal salt includes one or more of vanadium acetylacetonate, nickel acetylacetonate, chromium acetylacetonate, iron acetylacetonate, cobalt acetylacetonate and cerium acetylacetonate.

[0016] In some embodiments, the shaping process includes vacuum freeze-drying.

[0017] In some embodiments, the vacuum freeze-drying process comprises the following steps: cooling to -50°C~-120°C at a cooling rate of 0.5°C / min~2°C / min, and keeping warm for 1h~20h.

[0018] In some embodiments, the tantalum pentoxide and the carbon powder are mixed by ball milling;

[0019] The ball milling mixing is performed at a rotation speed of 50 r / min to 500 r / min, and the mixing time is 1 h to 6 h.

[0020] In some embodiments, the preparation method includes the following steps: mixing tantalum pentoxide, carbon powder and a dispersant, and drying to prepare a mixture.

[0021] In some embodiments, the preparation method satisfies at least one of the following characteristics:

[0022] (1) The dispersant includes one or more of anhydrous ethanol, deionized water, ethylene glycol, methanol and isopropanol;

[0023] (2) The drying temperature is 50°C to 200°C, the drying time is 10h to 25h, and the drying pressure is 200Pa to 1000Pa.

[0024] In some embodiments, the heat treatment includes a first heat treatment and a second heat treatment performed sequentially;

[0025] The first heat treatment comprises the following steps: heating to 1450°C~1550°C at a rate of 5°C / min~10°C / min, keeping the temperature for 2h~5h, and the gas pressure is 200Pa~1000Pa;

[0026] The second heat treatment comprises the following steps: heating to 1500° C. to 2100° C. at a rate of 1° C. / min to 6° C. / min, keeping the temperature for 4 h to 6 h, and an air pressure of 2000 Pa to 5000 Pa.

[0027] According to a second aspect of an embodiment of the present application, a tantalum carbide coating is provided, which is prepared using the above-mentioned preparation method.

[0028] According to a third aspect of an embodiment of the present application, a tantalum carbide product is provided, comprising the above-mentioned tantalum carbide coating.

[0029] Compared with traditional technologies, this application has the following beneficial effects:

[0030] In the preparation method of this application, lauric acid and ethyl cellulose are used as film-forming agents. The polymer chains of ethyl cellulose absorb energy through deformation and sliding, hindering further crack expansion. Simultaneously, the addition of a specific mass content of acetylacetonate metal salt can improve the fracture toughness of the tantalum carbide coating. The interaction of these substances results in the resulting tantalum carbide coating having excellent fracture toughness.

[0031] Furthermore, the slurry on the substrate surface is formed by vacuum freeze drying, and the dispersant and other solvents are directly sublimated into steam, thereby reducing the occurrence of microcracks on the surface of the tantalum carbide coating. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned objects, features and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the connotations of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Unless otherwise expressly stated, the various materials, reagents, and equipment and the like to which reference is made in the course of the present application are available from commercial vendors or can be prepared by conventional techniques described in the literature.

[0034] In the present application, "further", "furthermore", "in particular" and the like are used for the purpose of description, indicating differences in content, but should not be understood as limiting the scope of protection of the present application.

[0035] In the present application, "optionally", "optional" and "optional" mean optional, i.e. selected from any one of the two parallel schemes of "have" or "have not". If there are multiple "optional" in a technical solution, unless otherwise specified, and there is no contradictory or mutual restrictive relationship, each "optional" is independent.

[0036] In the present application, the technical features described in an open way include both the closed technical solution consisting of the listed features and the open technical solution containing the listed features.

[0037] In the present application, the numerical interval (i.e. the numerical range) is not specified, and the optional numerical distribution within the above numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e. the minimum value and the maximum value) of the numerical range, and each numerical value between the two numerical endpoints. If not specified, when the numerical interval refers only to the integers within the numerical interval, including the two endpoint integers of the numerical range and each integer between the two endpoints, in this paper, it is equivalent to directly listing each integer, such as t is an integer selected from 1-10, which means that t is any one integer selected from the integer group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. In addition, when multiple ranges are provided to describe characteristics or properties, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges therein.

[0038] The temperature parameters in the present application are not particularly limited, and both constant temperature treatment and variation within a certain temperature range are allowed. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. It is allowed to fluctuate within the range of, for example, ±5℃, ±4℃, ±3℃, ±2℃, ±1℃.

[0039] Some embodiments of the present application provide a method for preparing a tantalum carbide coating, comprising S10 to S30.

[0040] S10: mixing tantalum pentoxide and carbon powder to prepare a mixture;

[0041] S20: mixing the mixture, ethyl cellulose, lauric acid, terpineol and acetylacetonate metal salt to prepare a slurry;

[0042] S30: transferring the slurry to the surface of the substrate, and sequentially performing a forming process and a heat treatment to prepare a tantalum carbide coating;

[0043] Wherein, based on the total mass of the mixture, the mass content of the acetylacetonate metal salt is 2% to 9%.

[0044] Through extensive research, the inventors found that the mass ratio of the mixture and acetylacetonate metal salt has a significant effect on the fracture toughness and high-temperature cracking of the tantalum carbide coating; when the mass content of acetylacetonate metal salt is between 2% and 5%, the fracture toughness of the tantalum carbide coating gradually increases with the increase of the acetylacetonate metal salt content; when the mass content of acetylacetonate metal salt is between 5% and 9%, the fracture toughness begins to decrease; therefore, this application limits the mass content of acetylacetonate metal salt to 2% to 9%.

[0045] The acetylacetone in acetylacetone metal salts can complex with metal ions, resulting in uniform dispersion of the metal ions. Compared to traditional metal ion doping, this reduces the risk of metal ion agglomeration and metal powder explosion during the preparation process. Acetylacetone decomposes at high temperatures. Most importantly, the metal atoms pin the tantalum carbide grain boundaries during crystal growth, preventing abnormal grain growth and ultimately imparting excellent fracture toughness and high density to the tantalum carbide coating.

[0046] At the same time, the metal atoms evenly dispersed within the tantalum carbide coating pin the grain boundaries of each tantalum carbide grain during growth, ensuring that each tantalum carbide grain is small and evenly dispersed on the surface of the carbon-based material. Due to the high energy of grain boundaries, dislocations require more energy to cross them. Dislocations need to cross more grain boundaries when moving within the material, resulting in increased resistance, which hinders further crack expansion and thus improves the material's fracture toughness.

[0047] The hydrophobic ethoxy (-OC2H5) substituents in ethyl cellulose's molecular structure give it excellent hydrophobicity and compatibility with organic solvents. This property allows it to form a continuous, transparent, dense film layer upon dissolution in organic solvents (such as anhydrous ethanol) through solvent evaporation. Ethyl cellulose is a highly tough material whose characteristic unit is a polymer chain composed of six-membered heterocyclic rings with hydroxyl and ethyl ether groups. These polymer chains can deform and slide, thereby improving the smoothness of the initial coating interface and ensuring a defined coating thickness.

[0048] As an organic solvent, terpineol can adjust the viscosity and rheological properties of the slurry, making it easier to spread the slurry evenly during the coating process and reducing film defects. It is understandable that terpineol molecules have a certain flexible structure, which can weaken the interactions between polymer chains and facilitate their movement.

[0049] Lauric acid can effectively reduce the surface tension between liquids. When applied to the surface of a liquid, its molecules will arrange on the surface of the liquid to form a thin film, thereby reducing the energy of the liquid surface and making it easier for the liquid to form a stable film.

[0050] As an example, based on the total mass of the mixture, the mass content of acetylacetonate metal salt can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, or any value within the range formed by any two of the above point values.

[0051] Furthermore, based on the total mass of the mixture, the mass content of the acetylacetonate metal salt is 2% to 5%.

[0052] In some embodiments, in S10, the molar ratio of tantalum pentoxide to carbon powder is 1:(6.95-7).

[0053] As an example, the molar ratio of tantalum pentoxide to carbon powder can be 1:6.95, 1:6.96, 1:6.97, 1:6.98, 1:6.99, 1:7, or any value within the range formed by any two of the above ratios.

[0054] In some examples, the tantalum pentoxide is tantalum pentoxide particles.

[0055] It can be understood that controlling the molar ratio of tantalum pentoxide to carbon powder within the above range can enable tantalum pentoxide and carbon powder to fully react to form tantalum carbide.

[0056] In some embodiments, in S10, the tantalum pentoxide and the carbon powder are mixed by ball milling. It is understood that the tantalum pentoxide is ground into finer particles or powder by ball milling so that it can be fully mixed with the carbon powder.

[0057] In some examples, the ball milling mixing is performed at a speed of 50 rpm to 500 rpm and for a time of 1 h to 6 h.

[0058] For example, the ball milling speed can be 50 r / min, 100 r / min, 150 r / min, 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, or any value within the range formed by any two of the above values. The ball milling time can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, or any value within the range formed by any two of the above values.

[0059] In some embodiments, S10 includes: mixing tantalum pentoxide, carbon powder, and a dispersant, and drying to prepare a mixture.

[0060] In some examples, in S10 , the dispersant includes one or more of anhydrous ethanol, deionized water, ethylene glycol, methanol, and isopropyl alcohol.

[0061] In some examples, the amount of dispersant added is 50 mL to 300 mL.

[0062] In some examples, in S10 , the drying method is vacuum drying.

[0063] In some examples, in S10 , the drying temperature is 50° C. to 200° C., the drying time is 10 h to 25 h, and the pressure is 200 Pa to 1000 Pa.

[0064] As an example, the drying temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, or any value within a range between any two of the above values. The drying time can be 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, 21 h, 22 h, 23 h, 24 h, 25 h, or any value within a range between any two of the above values. The drying pressure can be 200 Pa, 300 Pa, 400 Pa, 500 Pa, 600 Pa, 700 Pa, 800 Pa, 900 Pa, 1000 Pa, or any value within a range between any two of the above values.

[0065] In some embodiments, in S20, the mass ratio of the mixture, ethyl cellulose, and lauric acid is 10:(2-4):(2-3).

[0066] As an example, the mass ratio of the mixture, ethyl cellulose and lauric acid can be 10:2:2, 10:2:3, 10:3:2, 10:3:3, 10:4:2, 10:4:3, or any value within the range formed by any two of the above ratios.

[0067] Further, the mass ratio of the mixture, ethyl cellulose and lauric acid is 10:3:2.

[0068] It should be noted that the weight and volume of the relevant components mentioned in the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of each component. Therefore, as long as the content of the relevant components in the present application is proportionally enlarged or reduced, it is within the scope disclosed in the embodiment of the present application.

[0069] In some embodiments, the substrate comprises one or more of a graphite crucible substrate, a carbon fiber substrate, and a graphene substrate.

[0070] In some embodiments, the acetylacetone metal salt comprises one or more of vanadium acetylacetonate (V(C5H7O2)3), nickel acetylacetonate (Ni(C5H7O2)2), chromium acetylacetonate (Cr(C5H7O2)3), iron acetylacetonate (Fe(C5H7O2)3), cobalt acetylacetonate (Co(C5H7O2)3), and cerium acetylacetonate (Ce(C5H7O2)3).

[0071] In some examples, the method further comprises a step of pretreating the substrate before transferring the slurry to the surface of the substrate.

[0072] Optionally, the step of pretreating the substrate comprises heat treating the substrate in an atmosphere gas. Further optionally, the temperature of the heat treatment is 1500°C to 2500°C.

[0073] Further optionally, the atmosphere gas comprises one or more of fluorine gas, chlorine gas, bromine gas, iodine gas, and astatine gas. It can be understood that, by using the above-mentioned halogen gas to treat the substrate, impurities in the substrate can be halogenated into low-boiling halides and volatilized and removed, and the substrate will not react with halogens under high-temperature conditions.

[0074] In some embodiments, the transferring is by one or more of smearing, spraying, sputtering, and the like.

[0075] In some examples, the thickness of the slurry transferred to the surface of the substrate is 100 μm to 300 μm.

[0076] In some embodiments, the shaping treatment is by vacuum freeze-drying. The vacuum freeze-drying can cause the dispersant and other solvents to directly sublimate into water vapor, thereby reducing the stress caused by volume changes, maintaining the integrity of the material structure, and enabling more uniform removal of moisture from the inside of the material, thereby reducing the occurrence of micro-cracks on the surface of the tantalum carbide coating.

[0077] In some embodiments, in S30, the vacuum freeze-drying treatment includes the following steps: cooling to -50°C~-120°C at a cooling rate of 0.5°C / min~2°C / min, and keeping the temperature for 1h~20h.

[0078] As an example, the cooling rate of the vacuum freeze-drying treatment can be 0.5℃ / min, 0.6℃ / min, 0.7℃ / min, 0.8℃ / min, 0.9℃ / min, 1.0℃ / min, 1.1℃ / min, 1.2℃ / min, 1.3℃ / min, 1.4℃ / min, 1.5℃ / min, 1.6℃ / min, 1.7℃ / min, 1.8℃ / min, 1.9℃ / min, 2.0℃ / min, or any value within the range formed by any two of the above point values.

[0079] As an example, the final temperature of the vacuum freeze-drying treatment can be -50°C, -60°C, -70°C, -80°C, -90°C, -100°C, -110°C, -120°C, or any value within the range formed by any two of the above point values.

[0080] As an example, the insulation time of the vacuum freeze-drying treatment can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, or any value within the range formed by any two of the above point values.

[0081] In some embodiments, in S30, the heat treatment includes a first heat treatment and a second heat treatment performed sequentially;

[0082] The first heat treatment comprises the following steps: heating to 1450°C~1550°C at a rate of 5°C / min~10°C / min, holding for 2h~5h, and an air pressure of 200Pa~1000Pa;

[0083] The second heat treatment includes the following steps: heating to 1500° C.~2100° C. at a rate of 1° C. / min~6° C. / min, keeping the temperature for 4h~6h, and the gas pressure value is 2000Pa~5000Pa.

[0084] It is understandable that a certain amount of porosity may exist in the material after the first heat treatment, which can affect key performance indicators such as mechanical properties, electrical conductivity, and thermal conductivity. The second heat treatment rearranges and grows the grains within the material, helping to eliminate defects (such as cracks and pores) introduced during the initial sintering process and resulting in a more uniform and finer grain distribution.

[0085] As an example, the heating rate of the first heat treatment can be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, or any value within the range formed by any two of the above point values. The final temperature of the first heat treatment can be 1450°C, 1460°C, 1470°C, 1480°C, 1490°C, 1500°C, 1510°C, 1520°C, 1530°C, 1540°C, 1550°C, or any value within the range formed by any two of the above point values. The holding time of the first heat treatment can be 2h, 3h, 4h, 5h, or any value within the range formed by any two of the above point values. The gas pressure value of the first heat treatment can be 200Pa, 300Pa, 400Pa, 500Pa, 600Pa, 700Pa, 800Pa, 900Pa, 1000Pa, or any value within the range formed by any two of the above point values.

[0086] As an example, the heating rate of the second heat treatment can be 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, or any value within the range formed by any two of the above values. The final temperature of the second heat treatment can be 1500°C, 1550°C, 1600°C, 1650°C, 1700°C, 1750°C, 1800°C, 1850°C, 1900°C, 1950°C, 2000°C, 2050°C, 2100°C, or any value within the range formed by any two of the above values. As an example, the gas pressure value of the second heat treatment can be 2000Pa, 2200Pa, 2400Pa, 2600Pa, 2800Pa, 3000Pa, 3200Pa, 3400Pa, 3600Pa, 3800Pa, 4000Pa, 4200Pa, 4400Pa, 4600Pa, 4800Pa, 5000Pa, or any value within the range formed by any two of the above point values.

[0087] Some embodiments of the present application also provide a tantalum carbide coating, which is prepared using the above-mentioned preparation method.

[0088] The tantalum carbide coating prepared by the above method has excellent fracture performance and high density, and has almost no cracks on the surface.

[0089] Some embodiments of the present application also provide a tantalum carbide product comprising the above-mentioned tantalum carbide coating.

[0090] In some embodiments, the tantalum carbide article includes a tantalum carbide coating and a substrate.

[0091] In some examples, the substrate includes a graphite crucible substrate.

[0092] Providing the above-mentioned tantalum carbide coating on the surface of a substrate such as a graphite crucible can effectively protect the graphite crucible and extend its service life.

[0093] The present application will be further described below in conjunction with specific examples and comparative examples, but they should not be construed as limiting the scope of protection of the present application. The raw materials involved in the following specific examples, unless otherwise specified, can all be sourced from commercial sources, the instruments used, unless otherwise specified, can all be sourced from commercial sources, and the processes involved, unless otherwise specified, are all routinely selected by those skilled in the art.

[0094] Example 1

[0095] (1) Preparation of the mixture: 442 g of Ta2O5 particles and 83.8 g of C powder (molar ratio of 1:6.98) were weighed and placed in a ball mill. 80 mL of anhydrous ethanol was added as a dispersant. The mixture was mixed at 425 rpm using a planetary ball mill for 6 h to obtain a mixed solution. After ball milling, the mixed solution was poured into a ceramic bowl and dried in a vacuum drying oven at 200°C for 24 h at a pressure of 60 Pa to obtain a mixed solution.

[0096] (2) Preparation of slurry: Weigh 100 g of the above-prepared mixture, 30 g of ethyl cellulose, and 20 g of lauric acid, dropwise add 20 mL of terpineol, 10 mL of anhydrous ethanol, and 9 g of vanadium acetylacetonate, and grind thoroughly to prepare a slurry. Place the above slurry in a spray gun and set aside.

[0097] (3) Chlorine gas is introduced and the graphite crucible substrate is heat treated at 2000°C.

[0098] (4) Slurry transfer: Take out the heat-treated graphite crucible substrate, and spray the surface of the graphite crucible substrate with the muzzle of the spray gun perpendicular to the surface of the graphite crucible substrate. The thickness of the wet film formed by spraying is controlled to be 30 μm.

[0099] (5) Molding treatment: Place the sprayed graphite crucible substrate in a vacuum freeze dryer, cool it to -60°C at a cooling rate of 0.5°C / min, and keep it warm for 12 hours.

[0100] (6) First heat treatment: Place the graphite crucible substrate treated by the vacuum dryer in a resistance furnace with argon as the protective atmosphere and a pressure of 500 Pa. Heat the temperature to 1500°C at a heating rate of 1°C / min and keep it warm for 4 h.

[0101] (7) Second heat treatment: using argon as the protective atmosphere with a gas pressure of 2000 Pa, continue heating to 2000°C at a heating rate of 0.5°C / min and keep warm for 4 hours; after cooling to room temperature, a dense tantalum carbide coating is formed on the surface of the graphite crucible substrate.

[0102] Example 2

[0103] The same as example 1, the difference is that the adding amount of ethyl cellulose and lauric acid in step (2) is different. Specifically, in example 2, step (2) is: taking 100 g of the above prepared mixture, 40 g of ethyl cellulose and 20 g of lauric acid, adding 20 mL of pine oil alcohol, 10 mL of anhydrous ethanol and 9 g of vanadium acetylacetone dropwise, grinding thoroughly, and preparing a slurry. Other steps and parameters in example 2 are basically the same as those in example 1.

[0104] Example 3

[0105] The same as example 1, the difference is that the adding amount of ethyl cellulose and lauric acid in step (2) is different. Specifically, in example 3, step (2) is: taking 100 g of the above prepared mixture, 30 g of ethyl cellulose and 30 g of lauric acid, adding 20 mL of pine oil alcohol, 10 mL of anhydrous ethanol and 9 g of vanadium acetylacetone dropwise, grinding thoroughly, and preparing a slurry. Other steps and parameters in example 3 are basically the same as those in example 1.

[0106] Example 4

[0107] The same as example 1, the difference is that the mass content of acetylacetone metal salt in step (2) is different. Specifically, in example 4, step (2) is: taking 95 g of the above prepared mixture, 30 g of ethyl cellulose and 20 g of lauric acid, adding 20 mL of pine oil alcohol, 10 mL of anhydrous ethanol and 9 g of vanadium acetylacetone dropwise, grinding thoroughly, and preparing a slurry; wherein the mass content of the mixture and the acetylacetone metal salt is 95:9. Other steps and parameters in example 4 are basically the same as those in example 1.

[0108] Example 5

[0109] The same as example 1, the difference is that the mass content of acetylacetone metal salt in step (2) is different. Specifically, in example 5, step (2) is: taking 100 g of the above prepared mixture, 30 g of ethyl cellulose and 20 g of lauric acid, adding 20 mL of pine oil alcohol, 10 mL of anhydrous ethanol and 4 g of vanadium acetylacetone dropwise, grinding thoroughly, and preparing a slurry; wherein the mass content of the mixture and the acetylacetone metal salt is 100:4. Other steps and parameters in example 5 are basically the same as those in example 1.

[0110] Example 6

[0111] The same as example 1, the difference is that the final temperature of vacuum freeze drying treatment in step (5) is different. Specifically, in example 6, the final temperature of vacuum freeze drying treatment is -50℃. Other steps and parameters in example 6 are basically the same as those in example 1.

[0112] Example 7

[0113] The method is substantially the same as Example 1, except that the final temperature of the vacuum freeze-drying treatment in step (5) is different. Specifically, the final temperature of the vacuum freeze-drying treatment in Example 7 is -100°C. The other steps and parameters in Example 7 are substantially the same as those in Example 1.

[0114] Example 8

[0115] The process is basically the same as that of Example 1, except that the molding process in step (5) is different. Specifically, the molding process in Example 8 is high-temperature drying: drying at 200°C for 12 hours. The other steps and parameters in Example 8 are basically the same as those in Example 1.

[0116] Comparative Example 1

[0117] The method is substantially the same as Example 1, except that terpineol is not added in step (2). Specifically, step (2) in Comparative Example 2 is as follows: 100 g of the above-prepared mixture, 30 g of ethyl cellulose, 20 g of lauric acid, 10 mL of anhydrous ethanol, and 9 g of vanadium acetylacetonate are weighed and thoroughly ground to prepare a slurry; the other steps and parameters in Comparative Example 1 are substantially the same as those in Example 1.

[0118] Comparative Example 2

[0119] The method is substantially the same as Example 1, except that no metal acetylacetonate is added in step (2). Specifically, step (2) in Comparative Example 2 is as follows: 100 g of the above-prepared mixture, 30 g of ethyl cellulose, and 20 g of lauric acid are weighed, 20 mL of terpineol and 10 mL of anhydrous ethanol are added dropwise, and the mixture is thoroughly ground to prepare a slurry. The other steps and parameters in Comparative Example 2 are substantially the same as those in Example 1.

[0120] Comparative Example 3

[0121] The process is substantially the same as Example 1, except that lauric acid is not added in step (2). Specifically, step (2) in Comparative Example 3 is as follows: 100 g of the mixture prepared above and 30 g of ethyl cellulose are weighed, 20 mL of terpineol, 10 mL of anhydrous ethanol, and 9 g of vanadium acetylacetonate are added dropwise, and the mixture is thoroughly ground to prepare a slurry. The other steps and parameters in Comparative Example 3 are substantially the same as those in Example 1.

[0122] Comparative Example 4

[0123] The process is substantially the same as Example 1, except that ethyl cellulose is not added in step (2). Specifically, step (2) in Comparative Example 4 is as follows: 100 g of the above-prepared mixture and 30 g of lauric acid are weighed, 20 mL of terpineol, 10 mL of anhydrous ethanol, and 9 g of vanadium acetylacetonate are added dropwise, and the mixture is thoroughly ground to prepare a slurry. The other steps and parameters in Comparative Example 4 are substantially the same as those in Example 1.

[0124] Comparative Example 5

[0125] The process is essentially the same as Example 1, except that in step (2), ethyl cellulose is replaced with an equal mass of hydroxyethyl cellulose. Specifically, step (2) in Comparative Example 5 is as follows: 100 g of the above-prepared mixture, 30 g of hydroxyethyl cellulose, and 30 g of lauric acid are weighed, 20 mL of terpineol, 10 mL of anhydrous ethanol, and 9 g of vanadium acetylacetonate are added dropwise, and the mixture is thoroughly ground to prepare a slurry. The other steps and parameters in Comparative Example 5 are essentially the same as those in Example 1.

[0126] Some step parameters in Examples 1 to 8 and Comparative Examples 1 to 5 are shown in Table 1.

[0127] Table 1

[0128]

[0129] Performance Testing

[0130] The fracture toughness of the tantalum carbide coatings prepared in the above examples and comparative examples was tested by a bending test method. The tantalum carbide coatings prepared in each example and comparative example were evaluated to see whether they cracked at 2500°C. The specific results are shown in Table 2.

[0131] Table 2

[0132]

[0133] As can be seen from the above table, the difference between Example 1 and Example 8 lies in the different molding methods. Compared with high-temperature drying, vacuum freeze drying can reduce the stress caused by volume change, maintain the integrity of the material structure, and make the moisture removal inside the material more uniform, thereby reducing the appearance of microcracks on the surface of the tantalum carbide coating.

[0134] Comparative Example 1 lacked terpineol, Comparative Example 2 lacked acetylacetonate, Comparative Example 3 lacked lauric acid, and Comparative Example 4 lacked ethyl cellulose. All of the resulting tantalum carbide coatings exhibited cracking. In Comparative Example 5, hydroxyethyl cellulose was used instead of ethyl cellulose. However, the higher viscosity of hydroxyethyl cellulose affected the adhesion and strength of the film, leading to bubbles and unevenness during film formation and, in turn, coating cracking.

[0135] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0136] The above embodiments only express several implementation ways of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation to the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for preparing a tantalum carbide coating, characterized in that: The steps include: Mixing tantalum pentoxide and carbon powder to prepare a mixture; the molar ratio of the tantalum pentoxide to the carbon powder is 1:(6.95-7); The mixture, ethyl cellulose, lauric acid, terpineol and acetylacetonate metal salt are mixed to prepare a slurry; the mass ratio of the mixture, the ethyl cellulose and the lauric acid is 10:(2-4):(2-3); Transferring the slurry to the surface of a substrate, and sequentially performing a forming process and a heat treatment to prepare the tantalum carbide coating; Wherein, based on the total mass of the mixture, the mass content of the acetylacetonate metal salt is 5% to 9%; The molding method includes a vacuum freeze-drying process; the heat treatment includes a first heat treatment and a second heat treatment performed sequentially; The first heat treatment comprises the following steps: heating to 1450°C~1550°C at a rate of 5°C / min~10°C / min, keeping the temperature for 2h~5h, and the gas pressure is 200Pa~1000Pa; The second heat treatment comprises the following steps: heating to 1500° C. to 2100° C. at a rate of 1° C. / min to 6° C. / min, keeping the temperature for 4 h to 6 h, and an air pressure of 2000 Pa to 5000 Pa.

2. The method for preparing a tantalum carbide coating according to claim 1, wherein: The preparation method satisfies at least one of the following characteristics: (1) The substrate includes one or more of a graphite crucible substrate, a carbon fiber substrate, and a graphene substrate; (2) The acetylacetonate metal salt includes one or more of vanadium acetylacetonate, nickel acetylacetonate, chromium acetylacetonate, iron acetylacetonate, cobalt acetylacetonate and cerium acetylacetonate.

3. The method for preparing a tantalum carbide coating according to claim 1, wherein: The vacuum freeze-drying process comprises the following steps: cooling the temperature to -50°C to -120°C at a cooling rate of 0.5°C / min to 2°C / min, and keeping the temperature for 1 hour to 20 hours.

4. The method for preparing a tantalum carbide coating according to any one of claims 1 to 3, characterized in that: The tantalum pentoxide and the carbon powder are mixed by ball milling; The ball milling mixing is performed at a rotation speed of 50 r / min to 500 r / min, and the mixing time is 1 h to 6 h.

5. The method for preparing a tantalum carbide coating according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: mixing tantalum pentoxide, carbon powder and a dispersant, and drying to prepare a mixture.

6. The method for preparing a tantalum carbide coating according to claim 5, characterized in that: The preparation method satisfies at least one of the following characteristics: (1) The dispersant includes one or more of anhydrous ethanol, deionized water, ethylene glycol, methanol and isopropanol; (2) The drying temperature is 50°C to 200°C, the drying time is 10h to 25h, and the drying pressure is 200Pa to 1000Pa.

7. A tantalum carbide coating, characterized in that: The method is prepared according to any one of claims 1 to 6.

8. A tantalum carbide product, characterized in that: Comprising the tantalum carbide coating according to claim 7.

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