Titanium-niobium carbide solid solution composite ceramic as well as preparation method and application thereof

Abstract

The invention discloses titanium-niobium carbide solid solution composite ceramic as well as a preparation method and application thereof. The preparation method of the titanium-niobium carbide solid solution composite ceramic comprises the following steps: uniformly mixing titanium carbide, niobium carbide and silicon powder, carrying out ball milling to obtain slurry, drying the slurry, and crushing to obtain mixed powder; wherein the molar ratio of the titanium carbide to the niobium carbide is 1: 9; and performing the mixed powder, and performing hot pressed sintering at the temperature of 1300-1600 DEG C to obtain the titanium-niobium carbide solid solution composite ceramic. The low-temperature sintering of the titanium-niobium-based composite ceramic is realized by utilizing the liquid phase effect generated in the sintering process of silicon, and a phase structure beneficial to improving the toughness of the material is generated in situ, so that the bending strength and the fracture toughness of the titanium-niobium-based composite ceramic are remarkably improved. The titanium-niobium-based composite ceramic prepared by the method is fine in microstructure, high in density and excellent in comprehensive mechanical property.

Description

Technical Field

[0001] This invention belongs to the field of multiphase ceramic materials technology, and particularly relates to a titanium-niobium carbide solid solution multiphase ceramic, its preparation method and application. Background Technology

[0002] Titanium carbide (TiC) ceramics are widely used in high-temperature environments due to their high hardness, excellent wear resistance, and extremely high melting point, such as in key components of rocket nozzles, turbine blades, and hypersonic aircraft. However, the strong covalent bonding and low self-diffusion coefficient in TiC ceramics lead to poor sintering performance; simultaneously, their inherently low fracture toughness (1.5-3.6 MPa·m) also contributes to their poor sintering properties. 1 / 2 The high temperature and humidity of TiC-NbC ceramics severely limit their further application in high-temperature structures. To improve these issues, domestic and international efforts typically focus on adding suitable additives to modify the properties of titanium carbide ceramics, such as ZrC, WC, SiC, ZrN, TiN, BN, AlN, carbon black, and graphene. One relatively effective method is to start at the atomic scale and partially replace Ti with Nb, which has the same structure, to form a (Ti,Nb)C solid solution. The lattice distortion caused by this substitution not only helps promote the densification process but also improves the material's strength and maintains good thermodynamic stability. However, even so, densification of the TiC–NbC ceramic system still requires temperatures as high as 2000℃, which restricts its industrial application. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a titanium-niobium carbide solid solution multiphase ceramic, its preparation method, and its application, thereby solving the technical problems of poor sintering properties and fracture toughness of existing titanium-niobium based multiphase ceramics.

[0004] The objective of this invention is achieved through the following technical solution: A method for preparing a titanium-niobium carbide solid solution multiphase ceramic includes the following steps: Titanium carbide, niobium carbide and silicon powder are mixed evenly and then ball-milled to obtain a slurry. The slurry is dried and crushed to obtain a mixed powder. The molar ratio of titanium carbide to niobium carbide is 1:9. After the mixed powder is preformed, it is hot-pressed and sintered at 1300~1600℃ to obtain the titanium niobium carbide solid solution multiphase ceramic.

[0005] In this invention, silicon is introduced as a sintering aid. The reaction between carbide and silicon (Si) can significantly reduce the sintering temperature, while the silicon carbide (SiC) generated simultaneously can refine the grains and improve the mechanical properties and oxidation resistance of the ceramic. Furthermore, another in-situ product generated by the reaction of TiC and Si, namely Ti3SiC2, has an atomic configuration with alternating Ti-C layers (strong covalent bonds) and Si layers (weak metallic bonds). During crack propagation, interfacial delamination preferentially occurs in the weakly bonded Si layer, leading to crack deflection and bifurcation, which can significantly improve the fracture toughness of TiC-based ceramics.

[0006] Preferably, the mass of the silicon powder is 1 to 30% of the total mass of titanium carbide and niobium carbide.

[0007] Preferably, anhydrous ethanol is used as the solvent in the ball milling process.

[0008] In this invention, the purpose of ball milling followed by drying and crushing is to achieve thorough mixing of the powder and improve its sintering activity. The specific implementation of ball milling is not limited, as long as uniform mixing is achieved. In some specific embodiments, one of the following methods may be used: Method 1: Use a drum ball mill with a ball-to-material ratio of 5~50:1, a rotation speed of 50~300 r / min, and a mixing time of 5~48 h; Method 2: Use a drum ball mill with a ball-to-material ratio of 20~50:1, a rotation speed of 300~800 r / min, and a mixing time of 5~24 h; Method 3: Use a planetary ball mill with a ball-to-material ratio of 5~30:1, a rotation speed of 100~400 r / min, and a mixing time of 12~24 h.

[0009] Preferably, the drying temperature is 60~80℃.

[0010] Preferably, the preforming refers to loading the mixed powder into a mold and pressing it into shape under a pressure of 1~10MPa.

[0011] Preferably, the pressure of the hot pressing sintering is 10~50MPa.

[0012] Preferably, the specific operation steps for hot pressing sintering at 1300~1600℃ are as follows: First, pressurize to 50MPa before raising the temperature from room temperature to 1000℃. Then, while maintaining this pressure, continue to raise the temperature to 1300~1600℃ and hold for 1~4h. Finally, cool to room temperature at a rate of 10~30℃ / min.

[0013] Preferably, the hot pressing sintering is performed under a vacuum or inert gas atmosphere.

[0014] Preferably, the inert gas is argon, helium, or krypton.

[0015] The titanium-niobium carbide solid solution multiphase ceramics prepared by the above-mentioned method are titanium-niobium carbide solid solution multiphase ceramics.

[0016] The above-mentioned titanium-niobium carbide solid solution multiphase ceramics are used in the preparation of high-temperature resistant materials.

[0017] More preferably, the above-mentioned titanium-niobium carbide solid solution multiphase ceramics are used in the preparation of rocket nozzles, turbine blades and hypersonic aircraft.

[0018] Compared with the prior art, the beneficial effects of the present invention include: 1. This invention proposes for the first time a method for preparing titanium-niobium carbide solid solution multiphase ceramic materials by low-temperature reaction sintering. By adding a fixed proportion of niobium carbide to titanium carbide, Nb replaces Ti with the same structure to form a (Ti,Nb)C solid solution. This lattice distortion not only reduces the sintering temperature but also improves the strength of the ceramic while maintaining its thermodynamic stability. Adding an appropriate amount of silicon on this basis creates a liquid-phase sintering environment to lower the sintering temperature. Furthermore, silicon reacts in situ with titanium carbide to generate silicon carbide (SiC), which refines the grains and improves the mechanical properties of the ceramic. In addition, another in-situ product synthesized from the reaction of TiC and Si, Ti3SiC2, has an atomic configuration with alternating Ti-C layers (strong covalent bonds) and Si layers (weak metallic bonds). During crack propagation, interfacial delamination preferentially occurs in the weakly bonded Si layers, leading to crack deflection and bifurcation, which can significantly improve the fracture toughness of TiC-based ceramics.

[0019] 2. The process flow of this invention is easy to implement, greatly reducing the requirements for production equipment and achieving the goals of practical application, high efficiency, green environmental protection, and energy saving. It can obtain dense titanium-niobium carbide solid solution multiphase ceramic materials at relatively low sintering temperatures and pressures. Simultaneously, the material's comprehensive mechanical properties are also improved, with a flexural strength of 381~884MPa and a fracture toughness of 4.8~9.1MPa·m. 1 / 2 Its Vickers hardness is 11.8~21.9 GPa. Attached Figure Description

[0020] Figure 1 The XRD patterns of the titanium-niobium carbide solid solution multiphase ceramics prepared in Examples 1-3 are shown, where (a) corresponds to 2θ=10°~90°; and (b) corresponds to 2θ=30°~50°.

[0021] Figure 2 The images are SEM images of the titanium-niobium carbide solid solution composite ceramics prepared in Examples 1-3, where (a) corresponds to Example 1, (b) corresponds to Example 2, and (c) corresponds to Example 3.

[0022] Figure 3EDS diagrams of titanium-niobium carbide solid solution multiphase ceramics prepared in Examples 1-3 are shown, where (a) corresponds to Example 1, (b) corresponds to Example 2, and (c) corresponds to Example 3.

[0023] Figure 4 The XRD pattern and SEM image of the titanium-niobium carbide solid solution single-phase ceramic prepared in Comparative Example 1 are shown. (a) corresponds to the XRD pattern and (b) corresponds to the SEM image.

[0024] Figure 5 EDS image of the titanium-niobium carbide solid solution single-phase ceramic prepared in Comparative Example 1. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] The performance test methods of the examples and comparative examples are summarized below: Density: GB / T 25995-2010 (measurement of bulk density) + calculation of theoretical density (relative density).

[0027] Vickers hardness: GB / T 16534-2009 (Vickers hardness).

[0028] Bending strength: GB / T 6569-2006 (three-point bending).

[0029] Fracture toughness: GB / T 23806-2009 (single-sided notched beam method).

[0030] Example 1 A method for preparing a titanium-niobium carbide solid solution multiphase ceramic is described in the following steps: (1) Weigh titanium carbide powder, niobium carbide powder and silicon powder. The molar ratio of titanium carbide to niobium carbide is 1:9. The mass of silicon powder is 10% of the total mass of titanium carbide and niobium carbide. (2) After the powder weighed in step (1) is initially mixed with anhydrous ethanol to form a slurry, it is then ball-milled (the ball-to-material ratio is 10:1, the rotation speed is 150r / min, and the time is 24h). The resulting slurry is then dried at 80℃ for 24h and then crushed to finally obtain a uniformly mixed powder with high sintering activity. (3) The mixed powder obtained in step (2) is loaded into a graphite mold and pre-pressed at a pressure of 5 MPa (holding pressure for 300 s). The pre-pressed blank is then vacuum hot-pressed and sintered. The process is as follows: the pressure is increased to 50 MPa before the temperature rises from room temperature to 1000℃; then the pressure is maintained and the temperature is increased to 1400℃ and held for 1 h; finally, the temperature is cooled to room temperature at a rate of 10℃ / min to obtain titanium niobium carbide solid solution multiphase ceramic.

[0031] The titanium-niobium carbide solid solution multiphase ceramic prepared in Example 1 was tested and found to have a density of 99.0%, a Vickers hardness of 18.2 GPa, a flexural strength of 381 MPa, and a fracture toughness of 3.8 MPa·m. 1 / 2 .

[0032] Example 2 A method for preparing a titanium-niobium carbide solid solution multiphase ceramic is described in the following steps: (1) Weigh titanium carbide powder, niobium carbide powder and silicon powder. The molar ratio of titanium carbide to niobium carbide is 1:9. The mass of silicon powder is 10% of the total mass of titanium carbide and niobium carbide. (2) After the powder weighed in step (1) is initially mixed with anhydrous ethanol to form a slurry, it is then ball-milled (the ball-to-material ratio is 10:1, the rotation speed is 150r / min, and the time is 24h). The resulting slurry is then dried at 80℃ for 24h and then crushed to finally obtain a uniformly mixed powder with high sintering activity. (3) The mixed powder obtained in step (2) is loaded into a graphite mold and pre-pressed at a pressure of 5 MPa (holding pressure for 300 s). The pre-pressed blank is then vacuum hot-pressed and sintered. The process is as follows: the pressure is increased to 50 MPa before the temperature rises from room temperature to 1000 ℃; then the pressure is maintained and the temperature is increased to 1500 ℃ and held for 1 h; finally, the temperature is cooled to room temperature at a rate of 10 ℃ / min to obtain titanium niobium carbide solid solution multiphase ceramic.

[0033] The titanium-niobium carbide solid solution multiphase ceramic prepared in Example 2 was tested and found to have a density of 99.5%, a Vickers hardness of 21.9 GPa, a flexural strength of 449 MPa, and a fracture toughness of 4.8 MPa·m. 1 / 2 .

[0034] Example 3 A method for preparing a titanium-niobium carbide solid solution multiphase ceramic is described in the following steps: (1) Weigh titanium carbide powder, niobium carbide powder and silicon powder. The molar ratio of titanium carbide to niobium carbide is 1:9. The mass of silicon powder is 10% of the total mass of titanium carbide and niobium carbide. (2) After the powder weighed in step (1) is initially mixed with anhydrous ethanol to form a slurry, it is then ball-milled (the ball-to-material ratio is 10:1, the rotation speed is 150r / min, and the time is 24h). The resulting slurry is then dried at 80℃ for 24h and then crushed to finally obtain a uniformly mixed powder with high sintering activity. (3) The mixed powder obtained in step (2) is loaded into a graphite mold and pre-pressed at a pressure of 5 MPa (holding pressure for 300 s). The pre-pressed blank is then vacuum hot-pressed and sintered. The process is as follows: the pressure is increased to 50 MPa before the temperature rises from room temperature to 1000 ℃; then the pressure is maintained and the temperature is increased to 1600 ℃ and held for 1 h; finally, the temperature is cooled to room temperature at a rate of 10 ℃ / min to obtain titanium niobium carbide solid solution multiphase ceramic.

[0035] The titanium-niobium carbide solid solution multiphase ceramic prepared in Example 3 was tested and found to have a density of 99.9%, a Vickers hardness of 20.3 GPa, a flexural strength of 465 MPa, and a fracture toughness of 5.1 MPa·m. 1 / 2 .

[0036] Figure 1 The XRD patterns of the titanium-niobium carbide solid solution multiphase ceramics prepared in Examples 1-3 are shown, where (a) corresponds to 2θ = 10°~90°; (b) corresponds to 2θ = 30°~50°; 1400-10Si corresponds to Example 1, 1500-10Si corresponds to Example 2, and 1600-10Si corresponds to Example 3. Figure 1 It can be seen that the titanium-niobium carbide solid solution multiphase ceramics prepared in Examples 1-3 exhibit diffraction peaks of (Ti,Nb)C solid solution, and the phase structure is face-centered cubic (FCC) with no impurity phases present, proving that the present invention successfully prepared titanium-niobium carbide solid solutions. Furthermore, the intensity of the diffraction peaks of (Ti,Nb)C solid solution increases with increasing sintering temperature.

[0037] Figure 2 SEM images of the titanium-niobium carbide solid solution multiphase ceramics prepared in Examples 1-3 are shown, where (a) corresponds to Example 1, (b) corresponds to Example 2, and (c) corresponds to Example 3. Figure 2 It can be seen that Example 1 has a small number of pores due to the low sintering temperature, but the microstructure is fine. Example 2 has a high density, no obvious pores, and a small number of lath-shaped Ti3SiC2 particles in the microstructure. Example 3 has a high density, no obvious pores, and the size of the lath-shaped Ti3SiC2 particles in the microstructure is significantly increased.

[0038] Figure 3 EDS diagrams of the titanium-niobium carbide solid solution multiphase ceramics prepared in Examples 1-3 are shown, where (a) corresponds to Example 1, (b) corresponds to Example 2, and (c) corresponds to Example 3. Figure 3 It can be seen that the Nb element in Example 1 exhibits segregation, which indicates that the sintering temperature is too low and the element diffusion is incomplete. The Nb element segregation in Example 2 disappears and the second phase is evenly distributed. The second phase in Example 3 is also evenly distributed.

[0039] Example 4 A method for preparing a titanium-niobium carbide solid solution multiphase ceramic is described in the following steps: (1) Weigh titanium carbide powder, niobium carbide powder and silicon powder. The molar ratio of titanium carbide to niobium carbide is 1:9. The mass of silicon powder is 20% of the total mass of titanium carbide and niobium carbide. (2) After the powder weighed in step (1) is initially mixed with anhydrous ethanol to form a slurry, it is then ball-milled (the ball-to-material ratio is 10:1, the rotation speed is 150r / min, and the time is 24h). The resulting slurry is then dried at 80℃ for 24h and then crushed to finally obtain a uniformly mixed powder with high sintering activity. (3) The mixed powder obtained in step (2) is loaded into a graphite mold and pre-pressed at a pressure of 5 MPa (holding pressure for 300 s). The pre-pressed blank is then vacuum hot-pressed and sintered. The process is as follows: the pressure is increased to 50 MPa before the temperature rises from room temperature to 1000 ℃; then the pressure is maintained and the temperature is increased to 1500 ℃ and held for 1 h; finally, the temperature is cooled to room temperature at a rate of 20 ℃ / min to obtain titanium niobium carbide solid solution multiphase ceramic.

[0040] The titanium-niobium carbide solid solution multiphase ceramic prepared in Example 4 was tested and found to have a density of 99.9%, a Vickers hardness of 13.3 GPa, a flexural strength of 884 MPa, and a fracture toughness of 9.1 MPa·m. 1 / 2 .

[0041] Example 5 A method for preparing a titanium-niobium carbide solid solution multiphase ceramic is described in the following steps: (1) Weigh titanium carbide powder, niobium carbide powder and silicon powder. The molar ratio of titanium carbide to niobium carbide is 1:9. The mass of silicon powder is 30% of the total mass of titanium carbide and niobium carbide. (2) After the powder weighed in step (1) is initially mixed with anhydrous ethanol to form a slurry, it is then ball-milled (the ball-to-material ratio is 10:1, the rotation speed is 150r / min, and the time is 24h). The resulting slurry is then dried at 80℃ for 24h and then crushed to finally obtain a uniformly mixed powder with high sintering activity. (3) The mixed powder obtained in step (2) is loaded into a graphite mold and pre-pressed at a pressure of 5 MPa (holding pressure for 300 s). The pre-pressed blank is then vacuum hot-pressed and sintered. The process is as follows: the pressure is increased to 50 MPa before the temperature rises from room temperature to 1000 ℃; then the pressure is maintained and the temperature is increased to 1500 ℃ and held for 1 h; finally, the temperature is cooled to room temperature at a rate of 20 ℃ / min to obtain titanium niobium carbide solid solution multiphase ceramic.

[0042] The titanium-niobium carbide solid solution multiphase ceramic prepared in Example 5 was tested and found to have a density of 99.9%, a Vickers hardness of 11.8 GPa, a flexural strength of 749 MPa, and a fracture toughness of 6.1 MPa·m. 1 / 2 .

[0043] Comparative Example 1 A method for preparing a titanium-niobium carbide solid solution single-phase ceramic, the specific steps of which are as follows: (1) Weigh titanium carbide powder and niobium carbide powder. The molar ratio of titanium carbide to niobium carbide is 1:9. (2) After the powder weighed in step (1) is initially mixed with anhydrous ethanol to form a slurry, it is then ball-milled (the ball-to-material ratio is 10:1, the rotation speed is 150r / min, and the time is 24h). The resulting slurry is then dried at 80℃ for 24h and then crushed to finally obtain a uniformly mixed powder with high sintering activity. (3) The mixed powder obtained in step (2) is loaded into a graphite mold and pre-pressed at a pressure of 5 MPa (holding pressure for 300 s). The pre-pressed blank is then vacuum hot-pressed and sintered. The process is as follows: the pressure is increased to 50 MPa before the temperature rises from room temperature to 1000 ℃; then the pressure is maintained and the temperature is increased to 2000 ℃ and held for 1 h; finally, the temperature is cooled to room temperature at a rate of 20 ℃ / min to obtain titanium niobium carbide solid solution single-phase ceramic.

[0044] The titanium-niobium carbide solid solution single-phase ceramic prepared in Comparative Example 1 was tested and found to have a density of 97.5%, a Vickers hardness of 16.5 GPa, a flexural strength of 366 MPa, and a fracture toughness of 3.4 MPa·m. 1 / 2 .

[0045] Figure 4 The XRD and SEM images of the titanium-niobium carbide solid solution single-phase ceramic prepared in Comparative Example 1 are shown, where (a) corresponds to the XRD pattern and (b) corresponds to the SEM image. Figure 4 It can be seen that the product prepared in Comparative Example 1 is a single-phase (Ti,Nb)C solid solution with uniform grain size distribution and an average grain size of about 5 μm. No individual grains show excessive growth. However, residual carbon is present at grain boundaries and within the grains, which may reduce the strength of the structure and make it prone to cracking under stress, eventually leading to material fracture.

[0046] Figure 5 The image shows the EDS (Electro-Dispersion Diagram) of the titanium-niobium carbide solid solution single-phase ceramic prepared in Comparative Example 1. From... Figure 5 It can be seen that Ti and Nb are evenly distributed, which means that the solid solution effect of the two is good. However, there is still some carbon aggregation. Carbon aggregation will weaken the strength of the matrix to a certain extent. Therefore, while ensuring the full solid solution of Ti and Nb, eliminating carbon aggregation can effectively improve the strength of the material.

[0047] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a titanium-niobium carbide solid solution multiphase ceramic, characterized in that, Includes the following steps: Titanium carbide, niobium carbide and silicon powder are mixed evenly and then ball-milled to obtain a slurry. The slurry is dried and crushed to obtain a mixed powder. The molar ratio of titanium carbide to niobium carbide is 1:

9. After the mixed powder is preformed, it is hot-pressed and sintered at 1300~1600℃ to obtain the titanium niobium carbide solid solution multiphase ceramic.

2. The method for preparing titanium-niobium carbide solid solution multiphase ceramics according to claim 1, characterized in that, The mass of the silicon powder is 1 to 30% of the total mass of titanium carbide and niobium carbide.

3. The method for preparing titanium-niobium carbide solid solution multiphase ceramics according to claim 1, characterized in that, The ball milling process uses anhydrous ethanol as the solvent.

4. The method for preparing titanium-niobium carbide solid solution multiphase ceramics according to claim 1, characterized in that, The drying temperature is 60~80℃.

5. The method for preparing titanium-niobium carbide solid solution multiphase ceramics according to claim 1, characterized in that, The preforming refers to loading the mixed powder into a mold and pressing it into shape under a pressure of 1~10MPa.

6. The method for preparing titanium-niobium carbide solid solution multiphase ceramics according to claim 1, characterized in that, The pressure of the hot pressing sintering is 10~50MPa.

7. The method for preparing titanium-niobium carbide solid solution multiphase ceramics according to claim 6, characterized in that, The specific operating steps for hot pressing sintering at 1300~1600℃ are as follows: First, pressurize to 50MPa before raising the temperature from room temperature to 1000℃. Then, while maintaining this pressure, continue to raise the temperature to 1300~1600℃ and hold for 1~4h. Finally, cool to room temperature at a rate of 10~30℃ / min.

8. The method for preparing titanium-niobium carbide solid solution multiphase ceramics according to claim 1, characterized in that, The hot pressing sintering is carried out under a vacuum or inert gas atmosphere.

9. The titanium-niobium carbide solid solution multiphase ceramic prepared by the preparation method of any one of claims 1 to 8.

10. The application of the titanium-niobium carbide solid solution multiphase ceramic of claim 9 in the preparation of high-temperature resistant materials.

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