Tantalum carbide coating, preparation method thereof and tantalum carbide product

Abstract

The invention provides a tantalum carbide coating, a preparation method thereof 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, terpilenol and acetylacetone metal salt to prepare slurry; the slurry is transferred to the surface of a base material, forming treatment and heat treatment are conducted in sequence, and the tantalum carbide coating is prepared; wherein on the basis of the total mass of the mixture, the mass content of the acetylacetone metal salt is 2%-9%. According to the preparation method, lauric acid and ethyl cellulose are adopted as film-forming agents, meanwhile, terpilenol and acetylacetone metal salt with the specific mass content are added, and all the substances are matched with one another, so that the prepared tantalum carbide coating has the good fracture property.

Description

Technical Field

[0001] The present application relates to the technical field of tantalum carbide coatings, and particularly to a tantalum carbide coating, a preparation method thereof, and a tantalum carbide product. Background Art

[0002] Silicon carbide (SiC) single crystal is a semiconductor material with broad application prospects in new energy, aerospace, military and other fields. At present, when preparing silicon carbide single crystal by physical vapor transport method (PVT), usually a high temperature above 2400 °C is required. At the same time, it is required that the raw materials have high purity, and the crucibles and seed crystal holders and other supplies can withstand high temperatures and will not contaminate the silicon carbide raw materials and silicon carbide crystals. Currently, the commonly used crucibles and seed crystal holders and other supplies are made of graphite. At a high temperature above 2400 °C, SiC powder is prone to volatilize to generate silicon-rich gases such as Si and Si2C, and these gases will react with the graphite substrate, thereby damaging the graphite substrate.

[0003] To solve the above problems, the traditional technology is to provide a tantalum carbide coating on the surfaces of crucibles and seed crystal holders and other supplies that does not react with silicon carbide, graphite and silicon under high temperature conditions. This coating has good thermal physical matching with graphite and is an ideal coating material for the graphite components required for the growth of silicon carbide single crystals; tantalum carbide will not undergo chemical reactions with carbon powder, silicon powder and silicon carbide at high temperature, and can well protect the graphite substrate and reduce the diffusion of carbon atoms in the graphite substrate at high temperature, thereby ensuring the quality of SiC single crystals. At the same time, tantalum carbide has excellent high temperature resistance, can reduce the damage or generation of impurities of the graphite components in the silicon carbide single crystal growth furnace, provide an excellent growth environment for the growth of silicon carbide single crystals, thereby reducing crystal contamination, improving crystal quality, and prolonging the service life of the graphite components.

[0004] However, the density of the traditional tantalum carbide coating is relatively low and it is difficult to meet the user's requirements, so it needs to be further improved. Summary of the Invention

[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 including the tantalum carbide coating.

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

[0007] Mix tantalum pentoxide and carbon powder to prepare a mixture;

[0008] Mix the mixture, ethyl cellulose, lauric acid, terpineol and metal acetylacetonate to prepare a slurry;

[0009] Transfer the slurry to the surface of the substrate, and successively perform shaping treatment and heat treatment to prepare the tantalum carbide coating;

[0010] Among them, based on the total mass of the mixture, the mass content of the metal acetylacetonate is 2% - 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 matrix, a carbon fiber matrix and a graphene matrix;

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

[0016] In some embodiments, the method of the shaping treatment includes vacuum freeze-drying treatment.

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

[0018] In some embodiments, the way of mixing the tantalum pentoxide and the carbon powder is ball milling;

[0019] The rotation speed of the ball milling is 50 r / min - 500 r / min, and the time is 1 h - 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 absolute ethanol, deionized water, ethylene glycol, methanol and isopropyl alcohol;

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

[0024] In some of these embodiments, the heat treatment includes a first heat treatment and a second heat treatment performed in sequence;

[0025] The first heat treatment includes the following steps: heating up to 1450°C to 1550°C at a rate of 5°C / min to 10°C / min, holding for 2 h to 5 h, and the air pressure value being 200 Pa to 1000 Pa;

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

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

[0028] According to a third aspect of the embodiments of the present application, a tantalum carbide product is provided, which includes the above tantalum carbide coating.

[0029] Compared with the traditional technology, the present application has the following beneficial effects:

[0030] In the preparation method of the present application, lauric acid and ethyl cellulose are used as film-forming agents. The polymer chains of ethyl cellulose can absorb energy through their own deformation and sliding to hinder the further propagation of cracks; at the same time, a metal acetylacetonate salt with a specific mass content is added, which can improve the fracture toughness of the tantalum carbide coating. Therefore, the above substances cooperate with each other to enable the prepared tantalum carbide coating to have good fracture toughness.

[0031] Furthermore, by means of vacuum freeze-drying, the slurry on the surface of the substrate is formed, and solvents such as dispersants are directly sublimated into steam, so as to reduce the appearance of microcracks on the surface of the tantalum carbide coating. Detailed Embodiments

[0032] In order to make the above objects, features, and advantages of the present application more obvious and understandable, the specific embodiments of the present application will be described in detail. Many specific details are set forth in the following description in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by 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 technical field to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in this application can be obtained through the market or prepared by existing methods.

[0034] In this application, terms such as "further", "even further", "especially", etc. are used for descriptive purposes to indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0035] In this application, "optionally", "optional", "option" mean that it can be either present or absent, that is, it refers to any one of two alternative options of "present" or "absent". If "optional" appears multiple times in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" is independent.

[0036] In this application, for the technical features described in an open-ended manner, it includes both a closed technical solution composed of the listed features and an open technical solution including the listed features.

[0037] In this application, regarding numerical intervals (i.e., numerical ranges), unless otherwise specified, the optional numerical values are considered continuous within the above numerical intervals and include the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical range, as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as each integer between the two endpoints. In this article, it is equivalent to directly listing each integer. For example, when t is an integer selected from 1 - 10, it means that t is any 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 features or characteristics, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0038] For the temperature parameters in this application, unless otherwise specifically limited, both constant temperature treatment and fluctuations 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. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C are allowed.

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

[0040] S10: Mix tantalum pentoxide and carbon powder to prepare a mixed material;

[0041] S20: Mix the mixed material, ethyl cellulose, lauric acid, terpineol, and metal acetylacetonate to prepare a slurry;

[0042] S30: Transfer the slurry to the surface of a substrate, and successively perform shaping treatment and heat treatment to prepare a tantalum carbide coating;

[0043] Wherein, based on the total mass of the mixed material, the mass content of the metal acetylacetonate is 2% - 9%.

[0044] The inventors found through a large number of studies that the mass ratio of the mixed material and the metal acetylacetonate has an obvious influence on the fracture toughness and high-temperature cracking of the tantalum carbide coating; when the mass content of the metal acetylacetonate is between 2% and 5%, the fracture toughness of the tantalum carbide coating gradually increases with the increase of the content of the metal acetylacetonate; when the mass content of the metal acetylacetonate is between 5% and 9%, the fracture toughness begins to decline; therefore, the present application limits the mass content of the metal acetylacetonate to 2% - 9%.

[0045] In the metal acetylacetonate, acetylacetone can complex with metal ions, making the metal ions uniformly dispersed. Compared with the traditional doping of metal ions, it reduces the risks of metal ion agglomeration and metal powder explosion during the preparation process. Acetylacetone will decompose at high temperatures. Most importantly, during the growth of tantalum carbide crystals, the metal atoms will have a pinning effect on the grain boundaries of tantalum carbide, thereby preventing the abnormal growth of tantalum carbide grains, and further making the tantalum carbide coating have good fracture toughness and high density.

[0046] At the same time, the metal atoms uniformly dispersed inside the tantalum carbide coating will have a pinning effect on the grain boundaries of each tantalum carbide grain during the growth process, making each tantalum carbide grain small and uniformly dispersed on the surface of the carbon-based material. Since the grain boundary energy is relatively high, more energy is required for dislocations to cross the grain boundary. When dislocations move inside the material, they need to cross more grain boundaries, resulting in an increase in resistance and thus hindering the further propagation of cracks, and further improving the fracture toughness of the material.

[0047] The molecular structure of ethyl cellulose contains hydrophobic ethoxy (-OC2H5) substituents, making it have excellent hydrophobicity and organic solvent compatibility. This property enables it to form a continuous and transparent dense film layer through solvent evaporation after being dissolved in an organic solvent (such as absolute ethanol). It can be understood that ethyl cellulose is a high-toughness material, and its characteristic unit is a polymer chain composed of a six-membered heterocyclic unit with hydroxyl and ethyl ether groups. Its polymer chain can deform and slide by itself, thereby improving the smoothness of the pre-coating interface and ensuring that the coating has a quantitative thickness.

[0048] As an organic solvent, terpineol can adjust the viscosity and rheological properties of the slurry, making it easier for the slurry to spread evenly during the coating process and reducing film layer defects. It can be understood that the terpineol molecule has a certain flexible structure, which can weaken the interaction between polymer chains and make the movement of polymer chains easier.

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

[0050] As an example, based on the total mass of the mixture, the mass content of the metal acetylacetonate 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 metal acetylacetonate is 2% - 5%.

[0052] In some of the 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 the full reaction between tantalum pentoxide and carbon powder to form tantalum carbide.

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

[0057] In some examples, the rotation speed of the ball milling is 50 r / min - 500 r / min, and the time is 1 h - 6 h.

[0058] As an example, the rotation speed of ball milling and mixing 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 point values. The time of ball milling and mixing 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 point values.

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

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

[0061] In some examples, the addition amount of the dispersant 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 time is 10 h to 25 h, and the pressure value 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 the range formed by any two of the above point 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 the range formed by any two of the above point values. The drying pressure value can be 200 Pa, 300 Pa, 400 Pa, 500 Pa, 600 Pa, 700 Pa, 800 Pa, 900 Pa, 1000 Pa, or any value within the range formed by any two of the above point values.

[0065] In some of these 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 weights and volumes of the relevant components mentioned in this application can not only refer to the specific contents of each component, but also represent the proportional relationship of the weights between the components. Therefore, as long as the contents of the relevant components in the specification of this application are enlarged or reduced in proportion, they are within the scope disclosed in the specification of the embodiments of the present invention.

[0069] In some of the embodiments, in S20, the substrate includes one or more of a graphite crucible substrate, a carbon fiber substrate, and a graphene substrate.

[0070] In some of the embodiments, the metal acetylacetonate includes 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, before transferring the slurry to the surface of the substrate, the following steps are further included: pretreating the substrate.

[0072] Optionally, the step of pretreating the substrate includes: 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 includes one or more of fluorine gas, chlorine gas, bromine gas, iodine gas, and astatine gas. It can be understood that by treating the substrate with the above-mentioned halogen gases, the impurities in the substrate can be halogenated into low-boiling-point halides and volatilized and removed, and the matrix will not react with the halogen under high-temperature conditions.

[0074] In some of the embodiments, in S20, the transfer method includes, but is not limited to, coating, spraying, or sputtering, etc.

[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 of the embodiments, in S30, the forming treatment method includes vacuum freeze-drying treatment. The vacuum freeze-drying method can directly sublimate solvents such as dispersants into water vapor, thereby reducing the stress generated by volume change, maintaining the integrity of the material structure, and enabling the removal of moisture inside the material to be more uniform, and further reducing the appearance of microcracks on the surface of the tantalum carbide coating.

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

[0078] As an example, the cooling rate of the vacuum freeze-drying treatment can be 0.5°C / min, 0.6°C / min, 0.7°C / min, 0.8°C / min, 0.9°C / min, 1.0°C / min, 1.1°C / min, 1.2°C / min, 1.3°C / min, 1.4°C / min, 1.5°C / min, 1.6°C / min, 1.7°C / min, 1.8°C / min, 1.9°C / min, 2.0°C / 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 holding time of the vacuum freeze-drying treatment can be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, or any value within the range formed by any two of the above point values.

[0081] In some of these embodiments, in S30, the heat treatment includes a first heat treatment and a second heat treatment carried out in sequence;

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

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

[0084] It can be understood that there may be a certain porosity in the material after the first heat treatment, and these pores will affect key indicators such as the mechanical properties, electrical conductivity, and thermal conductivity of the material. By performing the second heat treatment, the grains inside the material will be rearranged and grown, which helps to eliminate defects (such as cracks, pores, etc.) generated during the primary sintering, and makes the distribution of the grains more uniform and finer.

[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 2 h, 3 h, 4 h, 5 h, or any value within the range formed by any two of the above point values. The air pressure value of the first heat treatment can be 200 Pa, 300 Pa, 400 Pa, 500 Pa, 600 Pa, 700 Pa, 800 Pa, 900 Pa, 1000 Pa, 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 point 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 point values. As an example, the air pressure value of the second heat treatment can be 2000 Pa, 2200 Pa, 2400 Pa, 2600 Pa, 2800 Pa, 3000 Pa, 3200 Pa, 3400 Pa, 3600 Pa, 3800 Pa, 4000 Pa, 4200 Pa, 4400 Pa, 4600 Pa, 4800 Pa, 5000 Pa, or any value within the range formed by any two of the above point values.

[0087] Some embodiments of the present application further provide a tantalum carbide coating prepared by the above preparation method.

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

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

[0090] In some of these embodiments, the above tantalum carbide product includes a tantalum carbide coating and a substrate.

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

[0092] Setting the above tantalum carbide coating on the surface of a matrix 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 it should not be construed as a limitation on the protection scope of the present application. For the raw materials involved in the following specific examples, unless otherwise specified, they can all be obtained commercially. For the instruments used, unless otherwise specified, they can all be obtained commercially. For the processes involved, unless otherwise specified, they are all conventional selections of those skilled in the art.

[0094] Example 1

[0095] (1) Preparation of the mixture: Weigh 442 g of Ta2O5 particles and 83.8 g of C powder (molar ratio 1:6.98) and place them in a ball mill jar. Add 80 mL of absolute ethanol as a dispersant and use a planetary ball mill to mix at a speed of 425 r / min for 6 h to obtain a mixed solution. After the ball milling is completed, pour the mixed solution into a ceramic bowl and place it in a vacuum drying oven. Dry at 200 °C for 24 h, with a pressure value of 60 Pa to obtain the mixture.

[0096] (2) Preparation of the slurry: Weigh 100 g of the mixture prepared above, 30 g of ethyl cellulose, and 20 g of lauric acid. Add dropwise 20 mL of terpineol, 10 mL of absolute ethanol, and 9 g of vanadyl acetylacetonate, and grind thoroughly to obtain the slurry. Place the above slurry in a spray gun for standby.

[0097] (3) Introduce chlorine gas and perform heat treatment on the graphite crucible matrix at 2000 °C.

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

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

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

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

[0102] Example 2

[0103] It is basically the same as Example 1, except that the addition amounts of ethyl cellulose and lauric acid in step (2) are different. Specifically, step (2) in Example 2 is as follows: Weigh 100 g of the above-prepared mixture, 40 g of ethyl cellulose, and 20 g of lauric acid, add dropwise 20 mL of terpineol, 10 mL of absolute ethanol, and 9 g of vanadyl acetylacetonate, and grind thoroughly to obtain a slurry. Other steps and parameters in Example 2 are basically the same as those in Example 1.

[0104] Example 3

[0105] It is basically the same as Example 1, except that the addition amounts of ethyl cellulose and lauric acid in step (2) are different. Specifically, step (2) in Example 3 is as follows: Weigh 100 g of the above-prepared mixture, 30 g of ethyl cellulose, and 30 g of lauric acid, add dropwise 20 mL of terpineol, 10 mL of absolute ethanol, and 9 g of vanadyl acetylacetonate, and grind thoroughly to obtain a slurry. Other steps and parameters in Example 3 are basically the same as those in Example 1.

[0106] Example 4

[0107] It is basically the same as Example 1, except that the mass content of the metal acetylacetonate in step (2) is different. Specifically, step (2) in Example 4 is as follows: Weigh 95 g of the above-prepared mixture, 30 g of ethyl cellulose, and 20 g of lauric acid, add dropwise 20 mL of terpineol, 10 mL of absolute ethanol, and 9 g of vanadyl acetylacetonate, and grind thoroughly to obtain a slurry; the mass content of the mixture and the metal acetylacetonate is 95:9. Other steps and parameters in Example 4 are basically the same as those in Example 1.

[0108] Example 5

[0109] It is basically the same as Example 1, except that the mass content of the metal acetylacetonate in step (2) is different. Specifically, step (2) in Example 5 is as follows: Weigh 100 g of the above-prepared mixture, 30 g of ethyl cellulose, and 20 g of lauric acid, add dropwise 20 mL of terpineol, 10 mL of absolute ethanol, and 4 g of vanadyl acetylacetonate, and grind thoroughly to obtain a slurry; the mass content of the mixture and the metal acetylacetonate is 100:4. Other steps and parameters in Example 5 are basically the same as those in Example 1.

[0110] Example 6

[0111] It is basically 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 6 is -50 °C. Other steps and parameters in Example 6 are basically the same as those in Example 1.

[0112] Example 7

[0113] It is basically 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. Other steps and parameters in Example 7 are basically the same as those in Example 1.

[0114] Example 8

[0115] It is basically the same as Example 1, except that the molding treatment method in step (5) is different. Specifically, the molding treatment method in Example 8 is high-temperature drying: drying at 200°C for 12 h. Other steps and parameters in Example 8 are basically the same as those in Example 1.

[0116] Comparative Example 1

[0117] It is basically the same as Example 1, except that no terpineol is added in step (2). Specifically, step (2) in Comparative Example 2 is as follows: Weigh 100 g of the above-prepared mixture, 30 g of ethyl cellulose, and 20 g of lauric acid, 10 mL of absolute ethanol, and 9 g of vanadyl acetylacetonate, and grind them thoroughly to obtain a slurry; other steps and parameters in Comparative Example 1 are basically the same as those in Example 1.

[0118] Comparative Example 2

[0119] It is basically 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: Weigh 100 g of the above-prepared mixture, 30 g of ethyl cellulose, and 20 g of lauric acid, add 20 mL of terpineol dropwise, 10 mL of absolute ethanol, and grind them thoroughly to obtain a slurry. Other steps and parameters in Comparative Example 2 are basically the same as those in Example 1.

[0120] Comparative Example 3

[0121] It is basically the same as Example 1, except that no lauric acid is added in step (2). Specifically, step (2) in Comparative Example 3 is as follows: Weigh 100 g of the above-prepared mixture, 30 g of ethyl cellulose, add 20 mL of terpineol dropwise, 10 mL of absolute ethanol, and 9 g of vanadyl acetylacetonate, and grind them thoroughly to obtain a slurry. Other steps and parameters in Comparative Example 3 are basically the same as those in Example 1.

[0122] Comparative Example 4

[0123] It is basically the same as Example 1, except that no ethyl cellulose is added in step (2). Specifically, step (2) in Comparative Example 4 is as follows: Weigh 100 g of the above-prepared mixture, 30 g of lauric acid, add 20 mL of terpineol dropwise, 10 mL of absolute ethanol, and 9 g of vanadyl acetylacetonate, and grind them thoroughly to obtain a slurry. Other steps and parameters in Comparative Example 4 are basically the same as those in Example 1.

[0124] Comparative Example 5

[0125] It is basically 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: Weigh 100 g of the above-prepared mixture, 30 g of hydroxyethyl cellulose, and 30 g of lauric acid, add dropwise 20 mL of terpineol, 10 mL of absolute ethanol, and 9 g of vanadyl acetylacetonate, and grind thoroughly to obtain a slurry. Other steps and parameters in Comparative Example 5 are basically 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 Test

[0130] The fracture toughness of the tantalum carbide coatings prepared in the above examples and comparative examples was tested by the bending test method; it was evaluated whether the tantalum carbide coatings prepared in each example and comparative example 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 forming method. Compared with high-temperature drying, vacuum freeze-drying can reduce the stress generated by volume change, maintain the integrity of the material structure, and make the removal of moisture inside the material more uniform, thereby reducing the appearance of microcracks on the surface of the tantalum carbide coating.

[0134] In Comparative Example 1, terpineol was not added, in Comparative Example 2, metal acetylacetonate salt was not added, in Comparative Example 3, lauric acid was not added, and in Comparative Example 4, ethyl cellulose was not added. Cracking occurred in the finally prepared tantalum carbide coatings. In Comparative Example 5, hydroxyethyl cellulose was used to replace ethyl cellulose, but the viscosity of hydroxyethyl cellulose was relatively high, which would affect the adhesion and strength of film formation, resulting in the appearance of bubbles or unevenness during the film-forming process, and further causing the coating to crack.

[0135] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0136] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A method for preparing a tantalum carbide coating, characterized in that, It includes the following steps: Mix tantalum pentoxide and carbon powder to prepare a mixture; Mix the mixture, ethyl cellulose, lauric acid, terpineol and metal acetylacetonate to prepare a slurry; Transfer the slurry to the surface of a substrate, and perform a shaping treatment and a heat treatment in sequence to prepare the tantalum carbide coating; Wherein, based on the total mass of the mixture, the mass content of the metal acetylacetonate is 2% - 9%.

2. The method for preparing a tantalum carbide coating according to claim 1, characterized in that, The preparation method satisfies at least one of the following characteristics: (1) The molar ratio of the tantalum pentoxide to the carbon powder is 1:(6.95 - 7); (2) The mass ratio of the mixture, the ethyl cellulose and the lauric acid is 10:(2 - 4):(2 - 3); (3) The substrate includes one or more of a graphite crucible matrix, a carbon fiber matrix and a graphene matrix; (4) The metal acetylacetonate 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 method of the shaping treatment includes vacuum freeze-drying treatment.

4. The method for preparing a tantalum carbide coating according to claim 3, wherein The vacuum freeze-drying treatment includes the following steps: cool down to -50°C to -120°C at a cooling rate of 0.5°C / min to 2°C / min, and keep warm for 1h to 20h.

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

6. The method for preparing a tantalum carbide coating according to any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: mix tantalum pentoxide, carbon powder and a dispersant, and dry to prepare a mixture.

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

8. The method for preparing a tantalum carbide coating according to any one of claims 1 to 4, characterized in that, The heat treatment includes a first heat treatment and a second heat treatment performed in sequence; The first heat treatment includes the following steps: heat up to 1450°C to 1550°C at a rate of 5°C / min to 10°C / min, keep warm for 2h to 5h, and the air pressure value is 200Pa to 1000Pa; The second heat treatment includes the following steps: heat up to 1500°C to 2100°C at a rate of 1°C / min to 6°C / min, keep warm for 4h to 6h, and the air pressure value is 2000Pa to 5000Pa.

9. A tantalum carbide coating, characterized in that, Prepared by using the preparation method described in any one of claims 1 to 8.

10. A tantalum carbide product, characterized in that, It contains the tantalum carbide coating described in claim 9.

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