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

Abstract

The invention discloses high-entropy carbonitride powder as well as application and a preparation method thereof, and relates to the technical field of ultrahigh-temperature ceramic powder, the chemical formula of the high-entropy carbonitride powder is (Zr < 0.45 > Ta < 0.2 > W < 0.15 > Mo < 0.1 > Nb < 0.05 > Cr < 0.05 >) C < x > N < 1-x >, and x is greater than or equal to 0.75 and less than or equal to 0.90. The powder is in a single face-centered cubic phase, and the particle size reaches the nanoscale or submicron scale. A high-temperature ablation-resistant device can be prepared through hot pressing sintering, spark plasma sintering and other methods, and a film can be formed on the surface of the device through a spraying method. The preparation method comprises the following steps: ball-milling and mixing zirconium chloride, molybdenum carbide and other raw materials in proportion in an argon atmosphere, and cooling in an ice-water bath; then under the protection of inert gas, synthesizing in plasma with the temperature of a core area not lower than 8000K; and after synthesis, carrying out ultrasonic dispersion in ethanol, filtering by a filter screen, standing, drying and then carrying out vacuum heat treatment to obtain the single-phase high-entropy carbonitride powder.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-high temperature ceramic powders, and in particular relates to a high-entropy carbonitride powder and an application and a preparation method thereof. Background Art

[0002] The rapid development of aerospace, nuclear energy, and hypersonic vehicle technologies is placing ever-more stringent demands on ultra-high-temperature ceramic thermal protection materials for use in extreme environments (>2000°C). Traditional single-component carbides, nitrides, and borides, while characterized by high melting points, are susceptible to oxidation volatilization or thermal shock failure in high-temperature oxidizing environments, and their mechanical properties struggle to meet the demands of complex operating conditions.

[0003] High-entropy, ultra-high-temperature ceramics are a new type of ceramic material, typically single-phase, multi-component compounds composed of four or more metal cations and anions. Due to their unique "high-entropy effect," high-entropy ceramics possess high strength, hardness, excellent wear resistance, and superior high-temperature strength compared to their constituent single-phase materials. High-entropy carbonitride ceramics combine the high hardness of carbides with the toughness of nitrides. The high configurational entropy effect generated by the disordered arrangement of multiple cations and anions significantly enhances the material's thermal stability, oxidation resistance, and ablation resistance. Currently, the most commonly used method for preparing ultra-high-temperature, high-entropy ceramics and their powders is to use single-component carbides and nitrides as raw materials, ball-milling the mixture, and then spark plasma sintering to produce them. However, the high-entropy ceramics prepared by this method have low purity, large powder particle size, high equipment cost, and low production efficiency, making them unsuitable for industrial-scale production. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-entropy carbonitride powder and its application and preparation method to solve the problems existing in the background technology. In this scheme, the high-entropy carbonitride ceramic powder has a nanometer particle size and has higher sintering activity. It can be used to prepare high-temperature ablation-resistant devices through methods such as hot pressing sintering and spark plasma sintering, and can also be formed into a film on the surface of the device by spraying.

[0005] To achieve the above object, the present invention provides the following technical solution: a high entropy carbonitride powder,

[0006] The chemical formula is (Zr 0.45 Ta 0.2 W 0.15 Mo 0.1 Nb 0.05 Cr 0.05 )C x N 1-x , wherein 0.75≤x≤0.90; the powder is a single face-centered cubic phase, and the particle size of the powder is nanometer or submicron level.

[0007] Preferably, the application method is as follows: the powder can be used to prepare high-temperature ablation-resistant devices by hot pressing, spark plasma sintering, or molding, or to prepare a coating on the device surface by spraying.

[0008] A method for preparing high entropy carbonitride powder comprises the following steps:

[0009] S1, raw material mixing: zirconium chloride, tantalum chloride, tungsten chloride, molybdenum carbide, niobium chloride, and chromium carbide raw material powders are ball-milled in proportion under an argon atmosphere, and then cooled in an ice-water bath for 1-2 hours to obtain a mixed raw material powder;

[0010] S2, high entropy powder synthesis: the mixed powder is fed into a plasma under an inert gas to undergo a synthesis reaction, wherein the temperature of the plasma core region is not less than 8000K;

[0011] S3, powder screening: ultrasonically disperse the synthesized powder in ethanol for 1-3 hours, filter it with a 2000-mesh filter under negative pressure, let the filtrate stand for 12 hours, and dry the lower powder in a vacuum drying oven at 120°C for 10 hours;

[0012] S4, powder post-processing: heat-treating the dried powder under vacuum to obtain a single-phase high-entropy carbonitride powder.

[0013] Preferably, the ball milling in step S1 adopts planetary ball milling or drum ball milling, the ball milling jar is lined with polytetrafluoroethylene, the grinding balls are zirconia, the ball-to-material ratio is 2:1-1:4, the ball milling speed is 20-300r / min, the ball milling time is 2-10h, and the ice water bath cooling time is 1-5h.

[0014] Preferably, the molar fractions of the raw materials in step S1 are: tantalum chloride 18%-22%, tungsten chloride 12%-17%, molybdenum chloride 8%-13%, niobium chloride 3%-6%, chromium chloride 2%-5%, and zirconium chloride as the balance.

[0015] Preferably, the plasma in step S2 is microwave plasma or induction plasma, the powder feeding gas is argon, and the working gas is a mixture of argon and methane, nitrogen, and hydrogen, or a mixture of argon and methane and ammonia.

[0016] Preferably, the working gas comprises 60-98 Vol%, methane 1-20 Vol%, nitrogen 1-15 Vol%, and hydrogen 0-5 Vol%; or 60-98 Vol%, methane 1-20 Vol%, and ammonia 1-20 Vol%, and the total working gas volume is 80-150 L / min.

[0017] Preferably, the vacuum heat treatment temperature in step S4 is 600-1000°C and the time is 1-2h; the vacuum degree in the furnace before heat treatment is lower than 10 -2 Pa, the pressure in the furnace is less than 10Pa during the heating process, and the heating rate is 5-10℃ / min.

[0018] The beneficial effects of the present invention are:

[0019] (1) The high-entropy carbonitride powder prepared by the present invention forms a single face-centered cubic solid solution phase, and XRD characterization confirms the presence of no impurity phases (such as metal elements, oxides, etc.). This structure originates from the synergistic effect of plasma ultra-high temperature synthesis and vacuum heat treatment: the temperature of the plasma core area ≥8000K promotes the rapid diffusion of multi-component atoms to form a solid solution, and the vacuum heat treatment (600-1000℃, 1-2h) further eliminates lattice defects, and finally obtains a single-phase powder with a purity of ≥99%. Compared with the problem of multi-phase coexistence caused by insufficient element diffusion in the traditional ball milling-sintering method, the present invention fundamentally improves the thermodynamic stability of the material.

[0020] (2) The powder particle size is controlled within the range of 50-500nm, and the specific surface area is 20-50m 2 / g, significantly higher than the micron-sized powders (specific surface area <5m 2 / g). This characteristic is due to the rapid cooling effect of plasma synthesis - high temperature plasma causes the raw materials to vaporize instantly and condense rapidly (cooling rate>10 4 K / s), inhibiting grain growth. The high sintering activity enables the powder to achieve a relative density > 95% during hot pressing (1600°C / 20MPa), reducing energy consumption by approximately 15% compared to traditional methods (requiring temperatures above 1800°C) and increasing the density of the sintered body by 10%-15%.

[0021] (3) The present invention proposes a high-entropy carbonitride powder and a preparation method thereof. The high-entropy ceramic (ZrTaWMoNbCr)CN, which has zirconium carbide as its main component, has the advantages of low cost, high mechanical strength, high thermodynamic stability, and excellent ablation resistance, and can be used in the field of aerospace thermal protection. At the same time, the present invention introduces a method for preparing high-entropy carbonitride powder, which has the advantages of a simple process, high purity of the prepared powder, and fine grains. This method has significant advantages in the preparation of multi-component carbide and nitride high-entropy materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 SEM image of a high entropy carbonitride ceramic powder in Example 1;

[0023] Figure 2 XRD pattern of a high-entropy carbonitride ceramic powder in Example 1. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Example 1:

[0026] 368g of zirconium chloride, 252g of tantalum chloride, 209g of tungsten chloride, 96g of molybdenum carbide, 47g of niobium chloride, and 28g of chromium carbide were weighed and mixed in a planetary ball mill at a ball-to-material ratio of 1:2 and a milling speed of 80 rpm under an argon atmosphere for 4 hours. The milled powder was cooled in ice water for 1 hour and then opened in an argon-filled glove box to obtain a mixed powder. The milled mixed powder was synthesized in a radio frequency induction plasma device with a rated power of 100 kW. The powder was fed using a rotary powder feeder at a speed of 4 rpm, and argon was used as the carrier gas. The radio frequency induction plasma device has two working gases: side gas and center gas. The side gas used a mixture of high-purity argon and nitrogen (≥99.99%), with an argon flow rate of 100 SLM and a nitrogen flow rate of 10 SLM. The central gas was a mixture of argon, methane, nitrogen, and hydrogen, with an argon flow rate of 9 SLM, a methane flow rate of 5 SLM, a nitrogen flow rate of 3 SLM, and a hydrogen flow rate of 1.5 SLM. During synthesis, the plasma power was 80 kW and the internal pressure of the reaction chamber was 70 kPa. Once the plasma arc stabilized, the raw material powder was evenly introduced into the plasma reaction zone. After the reaction, the reaction was allowed to cool for 30 minutes, and the pressure in the reaction chamber was slowly raised to atmospheric pressure using argon. The resulting powder was removed and ultrasonically dispersed in ethanol in an ultrasonic cleaner for 1 hour. The dispersed powder was then filtered using a water circulation pump to remove large particles formed during the synthesis process. The filtered liquid was allowed to stand for 12 hours, and the supernatant was removed. The lower powder was dried in a vacuum drying oven for 10 hours. The dried powder was then heat-treated in a vacuum sintering furnace at 950°C for 2 hours at a heating rate of 10°C / min. After the heat treatment, it was naturally cooled to room temperature. The heat-treated powder was subjected to SEM morphology analysis and XRD phase analysis. The results are as follows: Figure 1 and Figure 2 As shown, the carbon content and nitrogen content in the high entropy carbonitride were measured to be 8.31% and 2.52% respectively, so (Zr0.45Ta0.2W0.15Mo0.1Nb0.05Cr0.05)C0.76N0.24 high entropy carbonitride ceramic powder was prepared.

[0027] Example 2:

[0028] 368g of zirconium chloride, 252g of tantalum chloride, 209g of tungsten chloride, 96g of molybdenum carbide, 47g of niobium chloride, and 28g of chromium carbide were weighed and mixed in a planetary ball mill at a ball-to-material ratio of 1:2 and a speed of 80 rpm under an argon atmosphere for 4 hours. The milled powder was cooled in ice water for 1 hour and then opened in an argon-filled glove box to obtain a mixed powder. The milled mixed powder was synthesized in a radio frequency induction plasma device with a rated power of 100 kW. The powder was fed using a rotary disc powder feeder at a speed of 4 rpm, and argon was used as the carrier gas. The radio frequency induction plasma device has two working gases: side gas and center gas. The side gas used was high-purity argon (≥99.99%) at a flow rate of 100 SLM. The center gas was a mixture of argon, methane, and ammonia, with a flow rate of 9 SLM of argon, 5 SLM of methane, and 5 SLM of ammonia. During synthesis, the plasma power was 65 kW and the internal pressure of the reaction chamber was 100 kPa. Once the plasma arc stabilized, the raw material powder was evenly introduced into the plasma reaction zone. After the reaction, the reaction was cooled for 30 minutes, and the pressure in the reaction chamber was slowly raised to atmospheric pressure using argon. The powder was removed from the reaction and ultrasonically dispersed in an ultrasonic cleaner using ethanol as the solvent for 1 hour. The dispersed powder was then filtered using a water circulation pump to remove large particles formed during the synthesis process. The filtered liquid was allowed to stand for 12 hours, and the supernatant was removed. The lower powder was dried in a vacuum drying oven for 10 hours. The dried powder was then heat treated in a vacuum sintering furnace at 900°C for 2 hours at a heating rate of 10°C / min. After the heat treatment, the mixture was naturally cooled to room temperature. The carbon content and nitrogen content in the high entropy carbonitride were measured to be 9.46% and 1.22% respectively, so (Zr0.45Ta0.2W0.15Mo0.1Nb0.05Cr0.05)C0.88N0.22 high entropy carbonitride ceramic powder was prepared.

[0029] Example 3:

[0030] 368g of zirconium chloride, 252g of tantalum chloride, 209g of tungsten chloride, 96g of molybdenum carbide, 47g of niobium chloride, and 28g of chromium carbide were weighed separately and mixed. The mixture was then milled in a planetary ball mill with a ball-to-material ratio of 1:2 and a milling speed of 80r / min under an argon atmosphere for 4 hours. The milled powder was cooled in ice water for 1 hour and then opened in an argon-filled glove box to obtain a mixed powder. The milled mixed powder was synthesized in a radio frequency induction plasma device with a rated power of 100kw. A rotary powder feeder with a feeder speed of 4r / min was used for powder delivery, and argon was used as the carrier gas. The radio frequency induction plasma device has two working gases: side gas and center gas. The side gas used was a mixture of high-purity argon gas (99.99% or higher) and methane gas, with an argon flow rate of 120SLM and a methane flow rate of 2SLM. The central gas was a mixture of argon, methane, and ammonia, with an argon flow rate of 9 SLM, a methane flow rate of 6 SLM, and an ammonia flow rate of 3 SLM. During synthesis, the plasma power was 75 kW and the internal pressure of the reaction chamber was 100 kPa. Once the plasma arc stabilized, the raw material powder was evenly introduced into the plasma reaction zone. After the reaction, the reaction chamber was cooled for 30 minutes, and the pressure in the reaction chamber was slowly raised to atmospheric pressure using argon. The resulting powder was removed and ultrasonically dispersed in ethanol in an ultrasonic cleaner for 1 hour. The dispersed powder was then filtered using a water circulation pump to remove large particles formed during the synthesis process. The filtered liquid was allowed to stand for 12 hours, and the supernatant was removed. The lower powder was dried in a vacuum drying oven for 10 hours. The dried powder was then heat-treated in a vacuum sintering furnace at 850°C for 1.5 hours at a heating rate of 10°C / min. After the heat treatment, it was naturally cooled to room temperature. The carbon content and nitrogen content in the high entropy carbonitride were measured to be 10.12% and 1.27% respectively, so (Zr0.45Ta0.2W0.15Mo0.1Nb0.05Cr0.05)C0.89N0.11 high entropy carbide ceramic powder was prepared.

[0031] Comparative Example 1:

[0032] Referring to Example 1, other conditions remained unchanged, and the plasma power was changed to 30 kW. The prepared powder was determined to be a mixture of metal, carbide, and a small amount of nitride, and high entropy carbonitride ceramics could not be prepared.

[0033] Comparative Example 2:

[0034] Referring to Example 2, other conditions remain unchanged, the flow rate of ammonia in the central gas of the plasma is changed to 0.5 SLM, and the carbon content and nitrogen content in the preparation are measured to be 10.76% and 0.37% respectively. The nitrogen content in the prepared high entropy carbonitride ceramic does not meet the standard of 10%-25%.

[0035] A high-entropy carbonitride powder is characterized in that it can be directly used to prepare high-temperature ablation-resistant devices by hot pressing sintering, spark plasma sintering, or molding, or a coating can be prepared on the surface of the device by spraying.

[0036] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A high entropy carbonitride powder, characterized in that: The chemical formula is (Zr 0.45 Ta 0.2 W 0.15 Mo 0.1 Nb 0.05 Cr 0.05 )C x N 1-x , Wherein, 0.75≤x≤0.90; the powder is a single face-centered cubic phase, and the particle size of the powder is nanometer level or submicron level.

2. The high entropy carbonitride powder according to claim 1, characterized in that: The powder can be used to prepare high-temperature ablation-resistant devices by hot pressing, spark plasma sintering, and molding, or to prepare a coating on the surface of a device by spraying.

3. A method for preparing a high entropy carbonitride powder according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1, raw material mixing: zirconium chloride, tantalum chloride, tungsten chloride, molybdenum carbide, niobium chloride, and chromium carbide raw material powders are ball-milled in proportion under an argon atmosphere, and then cooled in an ice-water bath for 1-2 hours to obtain a mixed raw material powder; S2, high entropy powder synthesis: the mixed powder is fed into a plasma under an inert gas to undergo a synthesis reaction, wherein the temperature of the plasma core region is not less than 8000K; S3, powder screening: the synthesized powder was ultrasonically dispersed in ethanol for 1-3 h, filtered with a 2000 mesh filter under negative pressure, the filtrate was allowed to stand for 12 h, and the lower layer of powder was dried in a vacuum drying oven at 120 ° C for 10 h; S4, powder post-processing: heat-treating the dried powder under vacuum to obtain a single-phase high-entropy carbonitride powder.

4. The method for preparing high entropy carbonitride powder according to claim 3, wherein: The ball milling in step S1 adopts planetary ball milling or drum ball milling, the ball milling jar is lined with polytetrafluoroethylene, the grinding balls are zirconia, the ball-to-material ratio is 2:1-1:4, the ball milling speed is 20-300r / min, the ball milling time is 2-10h, and the ice water bath cooling time is 1-5h.

5. The method for preparing high entropy carbonitride powder according to any one of claims 3 or 4, characterized in that: The molar fractions of the raw materials in step S1 are: tantalum chloride 18%-22%, tungsten chloride 12%-17%, molybdenum chloride 8%-13%, niobium chloride 3%-6%, chromium chloride 2%-5%, and zirconium chloride as the balance.

6. The method for preparing high entropy carbonitride powder according to claim 3, wherein: The plasma in step S2 is microwave plasma or induction plasma, the powder feeding gas is argon, and the working gas is a mixture of argon and methane, nitrogen, and hydrogen, or a mixture of argon and methane and ammonia.

7. The method for preparing high entropy carbonitride powder according to claim 6, characterized in that: In the working gas of step S2, argon accounts for 60-98 Vol%, methane accounts for 1-20 Vol%, nitrogen accounts for 1-15 Vol%, and hydrogen accounts for 0-5 Vol%; or argon accounts for 60-98 Vol%, methane accounts for 1-20 Vol%, and ammonia accounts for 1-20 Vol%, and the total working gas volume is 80-150 L / min.

8. The method for preparing high entropy carbonitride powder according to claim 3, wherein: The vacuum heat treatment temperature in step S4 is 600-1000°C and the time is 1-2h; the vacuum degree in the furnace before heat treatment is lower than 10 -2 Pa, the pressure in the furnace is less than 10Pa during the heating process, and the heating rate is 5-10℃ / min.

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