Method for inducing amplitude decomposition of high-entropy carbide ceramics by plasma sintering

Abstract

The application relates to the technical field of high-entropy ceramics, and discloses a method for inducing amplitude-modulated decomposition of high-entropy carbide ceramic by plasma sintering, wherein transition metal carbides TiC, ZrC, HfC, TaC and VC are weighed, mixed, dried, ground, sieved and sintered to prepare a quinary high-entropy carbide ceramic (TiZrHfTaV)C; the sintering process is as follows: keeping the temperature and pressure at 2000 DEG C and 50 MPa for 10-15 min. The application provides a method for inducing amplitude-modulated decomposition of high-entropy carbide ceramic by plasma sintering, and an amplitude-modulated decomposition type multiphase solid solution is prepared by controlling the holding time; the application induces amplitude-modulated decomposition of high-entropy carbide ceramic by controlling the holding time, improves the mechanical properties, and provides a new means for microstructure design of high-entropy carbide ceramic.

Description

Technical Field

[0001] This invention relates to the field of high-entropy ceramics technology, and in particular to a method for amplitude modulation decomposition of high-entropy carbide ceramics induced by plasma sintering. Background Technology

[0002] Since its introduction in 2004, high-entropy materials have rapidly become a hot topic in materials science due to their unique "high-entropy effect," "lattice distortion effect," "hysteresis diffusion effect," and "cocktail effect." As an innovative material with revolutionary application prospects, this progress has led to a continuous increase in the types of high-entropy ceramic materials, rapidly evolving from initial oxide ceramics to multi-component systems such as carbides, nitrides, borides, silicides, and sulfides. Among them, high-entropy carbide ceramics exhibit superior comprehensive performance compared to traditional single-component carbide ceramics: in terms of mechanical properties, they have higher hardness and Young's modulus, stable structure, and can withstand high pressure and impact under extreme conditions; in terms of thermal properties, the lattice distortion and enhanced phonon scattering induced by multi-element doping significantly reduce their thermal conductivity, making them excellent high-temperature insulation materials.

[0003] Chinese invention patent CN120965331A, entitled "A Five-Element High-Entropy Carbide Ceramics and Their Preparation Method," prepared a (TiZrHfTaV)C single-phase high-entropy solid solution, but the mechanical properties of this five-element high-entropy carbide ceramic were still somewhat lacking. Chinese invention patent CN117800733B, entitled "A Spread-Modulated Decomposition Hardening Compound Carbide Ceramics and Their Preparation Method," describes a method that, after specific aging treatment, induces spread-modulated decomposition in the sample, improving mechanical properties. However, its technical route is complex, the reaction cycle is long, and post-processing is required.

[0004] Therefore, there is an urgent need for a method for plasma sintering-induced amplitude modulation decomposition of high-entropy carbide ceramics to solve the above-mentioned technical problems. Summary of the Invention The purpose of this invention is to solve the above-mentioned technical problems such as insufficient performance and complex process, and to provide a method for plasma sintering-induced amplitude-modulated decomposition of high-entropy carbide ceramics. The preparation method is simple and the performance is optimized at the same time, so as to expand the exploration field of high-entropy carbide ceramic systems and provide a new route for performance optimization.

[0005] To achieve the above objectives, the present invention is implemented according to the following technical solution: A method for plasma-induced amplitude modulation decomposition of high-entropy carbide ceramics includes the following steps: Transition metal carbides TiC, ZrC, HfC, TaC, and VC were weighed, mixed, dried, ground, sieved, and sintered to prepare the pentagonal high-entropy carbide ceramic (TiZrHfTaV)C. The sintering process is as follows: holding at 2000℃ and 50 MPa for 10-15 minutes.

[0006] More preferably, the sintering process is as follows: holding at 2000℃ and 50 MPa for 10 min.

[0007] More preferably, the sintering process is as follows: holding at 2000℃ and 50 MPa for 15 min.

[0008] The pentagonal high-entropy carbide ceramic (TiZrHfTaV)C prepared in this invention is an abbreviation for (TiZrHfTaV)C, not its chemical formula. The pentagonal high-entropy carbide ceramic (TiZrHfTaV)C prepared in this invention is a modulated decomposition type multiphase solid solution.

[0009] Preferably, the molar ratio of TiC, ZrC, HfC, TaC, and VC is 0.25: 0.25: 0.2: 0.2: 0.1; and the purity of TiC, ZrC, HfC, TaC, and VC is 99.5%.

[0010] Preferably, the mixing process is as follows: the transition metal carbide is ball-milled and wet-mixed to obtain a slurry; the ball milling speed is 300 rpm and the ball milling time is 16 h.

[0011] Specifically, the ball-to-material ratio during ball milling is 8:1. Ethanol and zirconium oxide grinding balls are added to the transition metal carbide, and wet mixing is performed using a planetary ball mill.

[0012] Preferably, the drying process is as follows: rotary evaporation is performed using a rotary evaporator to obtain a mixed powder.

[0013] Preferably, the rotary drying temperature is 50 °C and the rotary drying time is 60 min.

[0014] Preferably, the grinding and sieving process is as follows: the mixed powder is ground into fine powder using a mortar and pestle and then passed through a 200-mesh sieve to obtain the sieved powder.

[0015] Preferably, the sintering process is as follows: the sieved powder is loaded into a mold and sintered using an electric discharge plasma sintering furnace.

[0016] To prevent the sample from coming into contact with and becoming contaminated by the mold (graphite mold), carbon paper is used to wrap the inside of the mold to avoid contamination of the sample.

[0017] To avoid compositional segregation caused by multi-stage sintering, this process uses metal carbide powder as raw material and adopts a one-step sintering method for SPS sintering (discharge plasma sintering).

[0018] This invention involves ball milling and mixing five transition metal carbides, followed by rotary evaporation drying, and then simple grinding and sieving to control the powder particle size. The powder is then sintered in a spark plasma sintering furnace (SPS) at a constant temperature and pressure of 2000℃ and 50 MPa, with controlled holding time, to prepare a modulated decomposition-type multiphase solid solution. This preparation method has a short reaction cycle and simple process flow. The product performance is improved after modulated decomposition, and it has broad application prospects in fields such as high-temperature structural materials.

[0019] This invention improves the mechanical properties of samples by extending the holding time to induce amplitude modulation decomposition. The process of this invention involves simple raw material handling, and the amplitude modulation decomposition phenomenon is induced simply by controlling the holding time during plasma sintering, thereby enhancing the mechanical properties of the samples.

[0020] This invention induces amplitude-modulated decomposition by precisely controlling the sintering holding time. The method is simple and can achieve a secondary improvement on the original properties of high-entropy carbide ceramics, further broadening their application in extreme environments, high-end manufacturing and other fields.

[0021] Mechanism of action: In the preparation of the high-entropy carbide ceramics of this invention, the control of sintering process parameters has a decisive influence on its microstructure and properties. Among them, the control of holding time can induce a unique amplitude-modulated decomposition phenomenon in the material, providing a new route for performance improvement. Amplitude-modulated decomposition is a typical nucleation-free phase transition process, referring to the spontaneous decomposition of a single solid solution into coherent or semi-coherent solid solution phases with different compositions but the same crystal structure under specific thermodynamic conditions, forming a periodic micromorphology. At the same time, this type of phase separation can effectively improve the mechanical properties of ceramics, providing a prospect for the design of high-performance materials.

[0022] The five-element high-entropy carbide system involved in this invention obtains an amplitude-modulated decomposition type multiphase solid solution by extending the holding time. Its essence is that the metastable single solid solution (TiZrHfTaV)C is provided with sufficient diffusion conditions, and the atoms achieve selective redistribution through uphill diffusion. Thermodynamically, the atomic radii of multi-element transition metals differ. Although the high-entropy effect inhibits phase separation in the early stages of sintering, the mixing enthalpy of the system is not absolutely stable. When external conditions are met, the system will spontaneously transition to a state with lower free energy, and amplitude modulation decomposition is an effective way to achieve this energy reduction. Kinetically, the sintering temperature of 2000℃ provides sufficient thermal activation energy for atomic diffusion, while the holding time directly determines the degree of atomic diffusion: with short holding time, the atomic diffusion distance is limited, and it is difficult for multi-element elements to achieve significant regional enrichment, and the system still maintains a single solid solution structure. When the holding time is extended, the atomic diffusion kinetic conditions are met, and different elements will spontaneously migrate to their respective enrichment regions due to differences in atomic radius, chemical potential, and binding energy: elements with similar atomic radii and better chemical compatibility tend to aggregate to form one type of solid solution region, while other compatible elements form another type of solid solution region, ultimately forming a multiphase solid solution structure with alternating components through amplitude modulation decomposition. This type of phase boundary can hinder the movement of dislocations, thereby increasing the hardness and strength of the sample. At the same time, the specific amplitude modulation structure can deflect the dislocation slip, thereby simultaneously improving the toughness of the sample.

[0023] In terms of process, discharge plasma sintering technology reduces the diffusion activation energy, and 50 MPa axial pressure promotes particle rearrangement. Furthermore, the isothermal and isobaric one-step process avoids compositional segregation caused by multi-stage sintering, and suppresses preferential volatilization of low-melting-point components by controlling the heating rate. In terms of composition, phase separation is achieved by controlling the holding time to induce amplitude-modulated decomposition of high-entropy carbide ceramics, thereby improving the mechanical properties of the product.

[0024] Beneficial effects: This invention provides a method for plasma sintering-induced amplitude-modulated decomposition of high-entropy carbide ceramics. By controlling the holding time, amplitude-modulated decomposition type multiphase solid solution five-element high-entropy carbide ceramic (TiZrHfTaV)C is prepared. This invention improves the mechanical properties of high-entropy carbide ceramics by controlling the holding time to induce amplitude-modulated decomposition, while providing a new means for the microstructure design of high-entropy carbide ceramics. This invention uses a ball milling process, which promotes atomic diffusion and rearrangement during ball milling, thereby inhibiting grain coarsening and improving mechanical properties. Attached Figure Description

[0025] Figure 1 The XRD patterns of ceramic samples prepared at 2000 °C and 50 MPa in Comparative Example 1, Example 1 and Example 2 of this invention are shown. Figure 2The image shows a TEM image of a high-entropy carbide ceramic sample prepared at 2000 °C and 50 MPa in Example 2 of the present invention. Figure 3 The graph shows the hardness and fracture toughness test data of ceramic samples prepared at 2000 °C and 50 MPa in Comparative Example 1, Example 1 and Example 2 of this invention under a load of 9.8 N. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0027] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0028] There are no particular restrictions on the purity of any of the raw materials used in this invention; however, it is preferred to use materials with conventional purity levels used in the field.

[0029] All processes in this invention are referred to by abbreviations that are common abbreviations in the field. Each abbreviation is clear and specific in its relevant application area, and those skilled in the art can understand the conventional process based on the abbreviation.

[0030] In all the following examples and comparative examples, the purity of TiC, ZrC, HfC, TaC, and VC used was 99.5%.

[0031] Comparative Example 1 Five transition metal carbide powders were weighed and mixed according to the molar ratio of TiC: ZrC: HfC: TaC: VC = 0.25: 0.25: 0.2: 0.2: 0.1. Ethanol was added, and the mixture was ball-milled using zirconium oxide as the ball milling medium at a speed of 300 rpm and a ball-to-powder ratio of 8:1. After ball milling for 16 h, the mixture was removed, the slurry was poured out, and the powder was dried by rotary evaporation at 50℃ for 60 min. The dried powder was then simply ground using an agate mortar and pestle and passed through a 200-mesh sieve. The sieved powder was then placed into an SPS mold and held at 2000℃ and 50 MPa for 5 min. After heating was stopped, the mixture was allowed to cool naturally to room temperature and then the pressure was released to prepare (TiZrHfTaV)C high-entropy carbide ceramics.

[0032] Example 1 A method for plasma-induced amplitude modulation decomposition of high-entropy carbide ceramics includes the following steps: Five transition metal carbide powders were weighed and mixed according to the molar ratio of TiC: ZrC: HfC: TaC: VC = 0.25: 0.25: 0.2: 0.2: 0.1. Ethanol was added, and the mixture was ball-milled using zirconium oxide as the ball milling medium at a speed of 300 rpm and a ball-to-powder ratio of 8:1. After ball milling for 16 h, the mixture was removed, the slurry was poured out, and the powder was dried by rotary evaporation at 50 °C for 60 min. The dried powder was then simply ground using an agate mortar and pestle and passed through a 200-mesh sieve. The sieved powder was then placed into an SPS mold and held at 2000 °C and 50 MPa for 10 min. After heating was stopped, the mixture was allowed to cool naturally to room temperature and then the pressure was released to prepare (TiZrHfTaV)C high-entropy carbide ceramics.

[0033] Example 2 A method for plasma-induced amplitude modulation decomposition of high-entropy carbide ceramics includes the following steps: Five transition metal carbide powders were weighed and mixed according to the molar ratio of TiC: ZrC: HfC: TaC: VC = 0.25: 0.25: 0.2: 0.2: 0.1. Ethanol was added, and the mixture was ball-milled using zirconium oxide as the ball milling medium at a speed of 300 rpm and a ball-to-powder ratio of 8:1. After ball milling for 16 h, the mixture was removed, the slurry was poured out, and the powder was dried by rotary evaporation at 50 °C for 60 min. The dried powder was then simply ground using an agate mortar and pestle and passed through a 200-mesh sieve. The sieved powder was then placed into an SPS mold and held at 2000 °C and 50 MPa for 15 min. After heating was stopped, the mixture was allowed to cool naturally to room temperature and then the pressure was released to prepare (TiZrHfTaV)C high-entropy carbide ceramics.

[0034] like Figure 1 The figure shows the XRD patterns of ceramic samples prepared at 2000℃ and 50 MPa in Examples 1, 2, and 1 of the present invention. In the figure, "5 min" represents Comparative Example 1; "10 min" represents Example 1; and "15 min" represents Example 2.

[0035] like Figure 2 The image shown is a TEM image of the high-entropy carbide ceramic sample prepared at 2000℃ and 50 MPa in Example 2 of the present invention. Compared with Comparative Example 1, Example 1, and Example 2 above, the difference lies in the length of the heat preservation time during the sintering process, with the heat preservation time being extended in that order.

[0036] Comparing Comparative Example 1, Example 1, and Example 2 above, from Figure 1As can be seen, the XRD pattern of the sample prepared in Comparative Example 1 shows a single solid solution phase with sharp peaks; the sample prepared in Example 1 shows TiC and TaC phase separation with broadened peaks; the sample prepared in Example 2 still shows TiC and TaC phase separation, with the TiC peak intensity higher than in Example 1 and the peak shape further broadened, indicating a higher degree of amplitude modulation decomposition.

[0037] from Figure 2 (a) Figure 2 (b) Figure 2 As can be seen in (c), the sample obtained in Example 2 exhibits obvious phase separation on its surface, forming two distinct phases, and the direction of the stripe ends is disordered, indicating a tendency for excessive amplitude modulation decomposition. Figure 2 (d) It can be concluded that Zr, Hf, and Ta, with large atomic radii, tend to segregate within the same phase and increase the lattice constant, while Ti and V, with small atomic radii, are enriched in another phase, forming periodic lattice fringes. From Figure 2 Multiple dislocation regions can be observed in (e), indicating that under the action of amplitude modulation decomposition, the interface and strain field of the sample prepared in Example 2 hinder the movement of dislocations and the dislocations can slide and deflect between modulation layers, thereby improving the mechanical properties of the sample.

[0038] like Figure 3 The figure shows the hardness and fracture toughness test data of ceramic samples prepared at 2000 °C and 50 MPa in Comparative Example 1 and Examples 1 and 2 of the present invention under a load of 9.8 N; in the figure, "5 min" represents Comparative Example 1; "10 min" represents Example 1; and "15 min" represents Example 2.

[0039] from Figure 3 In this study, the sample in Example 1 of the present invention achieved a hardness of 24.08 GPa and a fracture toughness of 3.82 MPa·m under a load of 9.8 N. 1 / 2 In Example 2, the sample achieved a hardness of 23.84 GPa and a fracture toughness of 3.61 MPa·m under a load of 9.8 N. 1 / 2 Compared to the samples in Comparative Example 1, which did not exhibit amplitude-modulated decomposition, the mechanical properties of all samples were improved, and the effect was significant.

[0040] Combination Figure 1-3 The above phenomena indicate that when the holding time is extended during this sintering process, plasma sintering will induce amplitude modulation decomposition of high-entropy carbide ceramics, thereby improving the mechanical properties of the prepared samples.

[0041] This invention utilizes discharge plasma sintering at a certain temperature and pressure, and by extending the holding time, induces amplitude modulation decomposition of high-entropy carbides to form a multiphase solid solution, thereby realizing the amplitude modulation decomposition of high-entropy carbide ceramics induced by plasma sintering.

[0042] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for plasma-induced amplitude-modulated decomposition of high-entropy carbide ceramics, characterized in that, Includes the following steps: Transition metal carbides TiC, ZrC, HfC, TaC, and VC were weighed, mixed, dried, ground, sieved, and sintered to prepare the pentagonal high-entropy carbide ceramic (TiZrHfTaV)C. The sintering process is as follows: holding at 2000 ℃ and 50 MPa for 10-15 min.

2. The method for plasma-induced amplitude-modulated decomposition of high-entropy carbide ceramics according to claim 1, characterized in that: The molar ratio of TiC, ZrC, HfC, TaC, and VC is 0.25: 0.25: 0.2: 0.2: 0.1; the purity of TiC, ZrC, HfC, TaC, and VC is 99.5%.

3. The method for plasma sintering-induced amplitude-modulated decomposition of high-entropy carbide ceramics according to claim 1, characterized in that: The mixing process is as follows: transition metal carbides are ball-milled and wet-mixed to obtain a slurry; the ball milling speed is 300 rpm and the ball milling time is 16 h.

4. The method for plasma sintering-induced amplitude-modulated decomposition of high-entropy carbide ceramics according to claim 1, characterized in that: The drying process is as follows: rotary evaporator is used for rotary drying to obtain a mixed powder.

5. The method for plasma sintering-induced amplitude-modulated decomposition of high-entropy carbide ceramics according to claim 4, characterized in that: The rotary drying temperature was 50 ℃, and the rotary drying time was 60 min.

6. The method for plasma sintering-induced amplitude-modulated decomposition of high-entropy carbide ceramics according to claim 1, characterized in that: The grinding and sieving process is as follows: the mixed powder is ground into fine powder using a mortar and pestle and then passed through a 200-mesh sieve to obtain the sieved powder.

7. The method for plasma sintering-induced amplitude-modulated decomposition of high-entropy carbide ceramics according to claim 1, characterized in that: The sintering process is as follows: the sieved powder is loaded into a mold and sintered in a discharge plasma sintering furnace.

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