High-purity high-entropy carbonitride powder as well as preparation method and application thereof
High-entropy carbonitride powders were prepared by a two-step method involving low-temperature pretreatment and high-temperature homogenization, which solved the problems of uneven composition and residual oxygen in traditional methods. This method produces high-purity high-entropy carbonitride powders with controllable nitrogen content, suitable for high-performance ceramic materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-12
- Publication Date
- 2026-04-07
AI Technical Summary
Existing technologies struggle to prepare high-purity, single-phase, and controllable nitrogen-content high-entropy carbonitride powders, as they suffer from phase separation, residual oxygen, and insufficient nitrogen content.
A two-step process of low-temperature pretreatment and high-temperature homogenization was adopted, and high-purity high-entropy carbonitride powder was prepared by carbothermal reduction nitriding reaction and high-temperature sintering treatment. The oxygen content was controlled to be no higher than 0.15 wt.%, the nitrogen content was 1.15~5.70 wt.%, and the carbon content was 4.85~8.85 wt.%.
This method achieves high-purity, high-stoichiometric control of high-entropy carbonitride powders, solving the problems of uneven composition and oxygen residue in traditional methods. It produces powders with good uniformity and particle size distribution, suitable for ceramic material applications.
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Figure CN121800543A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-entropy ceramic powder preparation technology, and more specifically, relates to a high-purity high-entropy carbonitride powder, its preparation method, and its application. Background Technology
[0002] High-entropy carbonitrides are multi-component single-phase solid solutions consisting of five or more metallic elements occupying the cation sublattice in equimolar or near-equimolar ratios, while carbon and nitrogen jointly occupy the anion sublattice. Their complex composition allows them to combine the excellent hardness of carbides with the superior toughness of nitrides, making them promising materials for hypersonic vehicle thermal protection and cutting tool applications. However, achieving these superior properties in bulk ceramics hinges on the availability of high-quality high-entropy carbonitride powders.
[0003] The main synthetic routes for high-entropy carbonitride powders include precursor methods using carbide and nitride powders and carbothermal reduction nitridation. Currently, carbothermal reduction nitridation has become the most economically feasible method for synthesizing high-entropy carbonitride powders. For example, Zhou et al. synthesized (Ti,Nb,Ta,Mo,W)(C,N) via carbothermal reduction nitridation and found that the choice of carbon source and the synthesis process significantly affect the reaction kinetics and phase composition. Jing et al. successfully synthesized (Ti,Nb,Ta,Mo,W)(C,N) via carbothermal reduction nitridation at 1600 °C. 0.2 V 0.2 Nb 0.2 Ta 0.2 Mo 0.2) (C 0.9 N 0.1 By controlling the carbon-oxygen molar ratio and the holding time, a single-phase face-centered cubic structure with low oxygen content was obtained from the powder.
[0004] Despite these advances, the synthesis of high-entropy carbonitride powders with controlled stoichiometry, single-phase structure, high purity, and enhanced nitrogen content via carbothermic reduction nitridation remains challenging. First, in the high-temperature, single-step process, carbothermic reduction, carbide formation, nitridation, and solution homogenization occur simultaneously, making the reaction difficult to control and potentially leading to phase separation. Second, significant differences in reduction temperatures among the multi-component metal oxides result in incomplete conversion of refractory oxides (such as HfO2), leading to compositional inhomogeneity and oxygen residue. Third, the limited solid solubility of nitrogen in high-entropy carbonitrides at high temperatures often results in nitrogen content lower than the design value, leading to compositional deviations. Therefore, there is an urgent need to develop a new method for preparing high-purity, single-phase, nitrogen-content-controlled high-entropy carbonitride powders to meet the application requirements of high-performance ceramic materials. Summary of the Invention
[0005] To address the shortcomings and drawbacks of existing technologies, the present invention aims to provide a method for preparing high-purity, high-entropy carbonitride powders. This method, through a two-step process of low-temperature pretreatment and high-temperature homogenization, effectively solves the problems of phase separation, residual oxygen, and insufficient nitrogen content inherent in traditional single-step methods, producing (Ti) powders with uniform composition, high purity, and controllable nitrogen content. 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) x N 1-x High-entropy carbonitride powder, where 0.5 ≤ x ≤ 0.9.
[0006] Another object of the present invention is to provide a high-purity high-entropy carbonitride powder obtained by the above method. The high-entropy carbonitride powder has an oxygen content of no more than 0.15 wt.%, a nitrogen content of 1.15~5.70 wt.%, and a carbon content of 4.85~8.85 wt.%.
[0007] Another object of the present invention is to provide the application of the above-mentioned high-purity, high-entropy carbonitride powder.
[0008] The objective of this invention is achieved through the following technical solution: A method for preparing high-purity, high-entropy carbonitride powder includes the following steps: S1. According to the chemical formula (Ti) 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) x N 1-x ), where 0.5 ≤ x ≤ 0.9, TiO2 powder, V2O5 powder, Ta2O5 powder, Nb2O5 powder, HfO2 powder and carbon black are added to anhydrous ethanol and ball-milled, then dried and sieved to obtain a mixed powder; S2. Under a nitrogen atmosphere, at a flow rate of 55~60 L / h, the mixed powder is heated to 1400~1450℃ to carry out a carbothermic reduction nitridation reaction to obtain intermediate carbonitride powder; S3. The intermediate carbonitride powder is transferred to a graphite crucible and sintered at atmospheric pressure at 1650~1700℃ under a nitrogen atmosphere to perform high-temperature homogenization treatment, thereby obtaining high-purity high-entropy carbonitride powder with an oxygen content of no more than 0.15wt.%, a nitrogen content of 1.15~5.70wt.%, a carbon content of 4.85~8.85wt.%, and an average particle size of 0.3~0.5μm.
[0009] Preferably, the TiO2 powder, V2O5 powder, Ta2O5 powder, Nb2O5 powder, HfO2 powder and carbon black mentioned in step S1 have a purity of 99.9% or higher and an average particle size of about 0.8~1 μm.
[0010] Preferably, in step S1, the ball milling speed is 200~300 rpm, the ball milling time is 22~24 h, the drying temperature is 60~80℃, the drying time is 24~48 h, and the sieve aperture is 80~100 mesh.
[0011] Preferably, the purity of the nitrogen gas in step S2 is above 99.9%, the heating rate is 5~10℃ / min, and the carbothermic reduction nitriding reaction time is 3~4 h.
[0012] Preferably, the heating rate in step S3 is 10~15℃ / min, and the sintering time is 1~2h.
[0013] A high-purity, high-entropy carbonitride powder is prepared by the method described above.
[0014] The application of the high-purity, high-entropy carbonitride powder in the preparation of high-entropy carbonitride ceramics, cutting tool materials, thermal protective coating materials, or wear-resistant materials.
[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention employs a two-step synthesis strategy, using low-temperature pretreatment (1400~1450℃) for complete carbothermal reduction and effective nitrogen incorporation, followed by high-temperature homogenization (1650~1700℃) to achieve single-phase formation. This effectively solves the problems of multiphase coexistence, uneven composition, and residual oxygen that exist in traditional single-step methods.
[0016] 2. The high-entropy carbonitride powder prepared by this invention has high purity and excellent stoichiometric control. By reducing the amount of carbon black to increase the nitrogen content, the oxygen content is significantly reduced to 0.15 wt.%, and the nitrogen content reaches 5.7 wt.%, which is close to the theoretical design value.
[0017] 3. This invention clarifies the mechanistic advantages of the two-step method through thermodynamic analysis. In the low-temperature stage of 1400~1450℃, TiO2, V2O5, Ta2O5 and Nb2O5 have negative Gibbs free energies, while HfO2, although having a positive Gibbs free energy (+19.6kJ / mol), effectively removes gaseous CO and reduces its partial pressure through continuous nitrogen flow, driving the equilibrium to proceed in the positive direction and achieving complete reduction of HfO2. The Gibbs free energy of the carbonitride formation pathway is much lower than that of the carbide formation pathway, indicating that nitrogen participation enhances the thermodynamic driving force.
[0018] 4. The high-entropy carbonitride powder prepared by this invention has good morphology and particle size distribution. The particles are nearly spherical with smooth and clean surfaces, and the average particle size is 0.37 ± 0.08 μm. The particle size distribution is uniform, making it suitable for subsequent ceramic sintering applications.
[0019] 5. The two-step method of this invention is easy to industrialize and provides a feasible technical route for the mass production of high-quality, high-entropy carbonitride powders. Attached Figure Description
[0020] Figure 1 The present invention describes the process flow for preparing high-entropy carbonitride powders.
[0021] Figure 2 The image shows the XRD pattern of the high-entropy carbonitride powder from Example 1.
[0022] Figure 3 This is a SEM image of the high-entropy carbonitride powder from Example 1. Detailed Implementation
[0023] The present invention will be further described below with reference to specific embodiments, but these should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.
[0024] Example 1 1. According to the molecular formula (Ti 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) 0.55 N 0.45 TiO2 powder, V2O5 powder, Ta2O5 powder, Nb2O5 powder, and HfO2 powder (all with a purity of 99.9% and a particle size of 1 μm) were added to 28.2 mol of carbon black (with a purity of 99.9% and a particle size of 1 μm). Anhydrous ethanol was used as the ball milling medium, and ZrO2 balls were used as the grinding medium. The ball-to-material mass ratio was 5:1. The mixture was ball-milled at 200 rpm for 24 h, then rotary evaporated at 50℃ for 30 min, and then dried at 80℃ for 24 h. The mixture was then passed through an 80-mesh sieve to obtain a mixed powder.
[0025] 2. Place 15 g of the mixed powder into an alumina crucible, place it in a zirconia tube furnace, and heat it to 1450℃ at a rate of 5℃ / min under a nitrogen atmosphere (purity 99.99%, flow rate 60 L / h) and hold for 4 h to carry out a carbothermic reduction nitriding reaction (first step low-temperature pretreatment). After cooling, intermediate carbonitride powder is obtained.
[0026] 3. The intermediate carbonitride powder was transferred to a graphite crucible and placed in an atmospheric pressure sintering furnace. Under a nitrogen atmosphere, the temperature was increased to 1700℃ at a rate of 10℃ / min and sintered at atmospheric pressure for 2 hours for high-temperature homogenization. After cooling, high-entropy carbonitride powder was obtained. Figure 1 Its molecular formula is (Ti 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) 0.55 N 0.45 ).
[0027] Figure 2 The image shows the XRD pattern of the high-entropy carbonitride powder from Example 1. Figure 2 It can be seen that the powder is a single-phase face-centered cubic high-entropy carbonitride powder, and no obvious impurity phase diffraction peaks were detected, indicating that a single-phase high-entropy carbonitride powder has been formed. Figure 3 This is a SEM image of the high-entropy carbonitride powder from Example 1. (From...) Figure 3 It can be seen that the particles are nearly spherical with smooth surfaces, and the average particle size is approximately 0.35 ± 0.09 μm. Table 1 shows the C, N, and O content determination results of Example 1 using a carbon-sulfur analyzer and an oxygen-nitrogen analyzer. The calculated actual chemical composition is (Ti 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) 0.55 N 0.44 O 0.01 The actual x-value is approximately 0.55, which corresponds to the target component (C) designed in this embodiment. 0.55 N 0.45 They are basically the same.
[0028] Table 1 shows the carbon, oxygen, and nitrogen content of the high-entropy carbonitride powder in Example 1.
[0029] Example 2 The difference between this embodiment and Example 1 is that the amount of carbon black added in step 1 is 29.2 mol, to obtain (Ti 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) 0.65 N 0.35 High-entropy carbonitride powders.
[0030] The obtained powder is a single-phase face-centered cubic high-entropy carbonitride powder with symmetrical diffraction peaks and no low-angle shoulders. The powder particles are nearly spherical with smooth surfaces and an average particle size of approximately 0.36 ± 0.08 μm. The actual chemical composition is (Ti 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) 0.65 N 0.34 O 0.01 The actual x-value is approximately 0.65, which corresponds to the design target component (C). 0.65 N 0.35 They are basically the same.
[0031] Example 3 The difference between this embodiment and Example 1 is that the amount of carbon black added in step 1 is 30.2 mol, to obtain (Ti 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) 0.75 N 0.24 O 0.01 High-entropy carbonitride powder.
[0032] The obtained powder is a single-phase face-centered cubic high-entropy carbonitride powder with symmetrical diffraction peaks and no low-angle shoulders. The powder particles are nearly spherical with smooth surfaces and an average particle size of approximately 0.38 ± 0.07 μm. The actual chemical composition is (Ti 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) 0.75 N 0.24 O 0.01 The actual x-value is approximately 0.75, which corresponds to the design target component (C). 0.75 N 0.25 They are basically the same.
[0033] Example 4 The difference between this embodiment and Example 1 is that the amount of carbon black added in step 1 is 31.2 mol, to obtain (Ti 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) 0.85 N 0.15 High-entropy carbonitride powders.
[0034] The obtained powder is a single-phase face-centered cubic high-entropy carbonitride powder with symmetrical diffraction peaks and no low-angle shoulders. The powder particles are nearly spherical with smooth surfaces and an average particle size of approximately 0.4 ± 0.1 μm. The actual chemical composition is (Ti 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) 0.85 N 0.14 O 0.01 The actual x-value is approximately 0.85, which corresponds to the design target component (C). 0.85 N 0.15 The results are basically consistent, indicating that the preparation of single-phase high-entropy carbonitride powders with controllable composition can also be achieved at the high carbon end.
[0035] The high-entropy carbonitride powder prepared by this invention exhibits high purity and excellent stoichiometric control. By reducing the amount of carbon black to increase the nitrogen content, its oxygen content is no higher than 0.15 wt.%, nitrogen content is 1.15~5.7 wt.%, carbon content is 4.85~8.85 wt.%, and average particle size is 0.3~0.5 μm. This invention clarifies the mechanistic advantages of the two-step method through thermodynamic analysis. In the low-temperature stage of 1400~1450℃, TiO2, V2O5, Ta2O5, and Nb2O5 have negative Gibbs free energies, while HfO2, although having a positive Gibbs free energy (+19.6 kJ / mol), effectively removes gaseous CO and reduces its partial pressure through continuous nitrogen flow, driving the equilibrium forward and achieving complete reduction of HfO2. The Gibbs free energy of the carbonitride formation pathway is much lower than that of the carbide formation pathway, indicating that nitrogen participation enhances the thermodynamic driving force.
[0036] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A method for preparing high-purity, high-entropy carbonitride powder, characterized in that, Includes the following steps: S1. According to the chemical formula (Ti) 0.2 V 0.2 Ta 0.2 Nb 0.2 Hf 0.2 (C) x N 1-x ), where 0.5 ≤ x ≤ 0.9, TiO2 powder, V2O5 powder, Ta2O5 powder, Nb2O5 powder, HfO2 powder and carbon black are added to anhydrous ethanol and ball-milled, then dried and sieved to obtain a mixed powder; S2. Under a nitrogen atmosphere, at a flow rate of 55~60 L / h, the mixed powder is heated to 1400~1450℃ to carry out a carbothermic reduction nitridation reaction to obtain intermediate carbonitride powder; S3. The intermediate carbonitride powder is transferred to a graphite crucible and sintered at atmospheric pressure at 1650~1700℃ under a nitrogen atmosphere to perform high-temperature homogenization treatment, thereby obtaining high-purity high-entropy carbonitride powder with an oxygen content not exceeding 0.15wt.%, a nitrogen content of 1.15~5.7wt.%, a carbon content of 4.85~8.85wt.%, and an average particle size of 0.3~0.5μm.
2. The method for preparing high-purity, high-entropy carbonitride powder according to claim 1, characterized in that, The TiO2 powder, V2O5 powder, Ta2O5 powder, Nb2O5 powder, HfO2 powder and carbon black mentioned in step S1 all have a purity of 99.9% or higher and an average particle size of approximately 0.8~1 μm.
3. The method for preparing high-purity, high-entropy carbonitride powder according to claim 1, characterized in that, In step S1, the ball milling speed is 200~300 rpm, the ball milling time is 22~24 h, the drying temperature is 60~80℃, the drying time is 24~48 h, and the sieve aperture is 80~100 mesh.
4. The method for preparing high-purity, high-entropy carbonitride powder according to claim 1, characterized in that, In step S2, the purity of the nitrogen gas is above 99.9%, and the heating rate is 5~10℃ / min; the carbothermic reduction nitriding reaction takes 3~4 h.
5. The method for preparing high-purity, high-entropy carbonitride powder according to claim 1, characterized in that, The heating rate in step S3 is 10~15℃ / min, and the sintering time is 1~2h.
6. A high-purity, high-entropy carbonitride powder, characterized in that, The high-entropy carbonitride powder is prepared by the method described in any one of claims 1-5.
7. The application of the high-purity, high-entropy carbonitride powder according to claim 6 in the preparation of high-entropy carbonitride ceramics, cutting tool materials, thermal protective coating materials, or wear-resistant materials.