ZTA-based conductive ceramic composite material and preparation method and application thereof

Abstract

The invention discloses a ZTA-based conductive ceramic composite material as well as a preparation method and application thereof. The preparation method comprises the following steps: S1, carrying out dry mixing on ZTA micro powder and a thermal expansion coefficient regulator to obtain mixed powder; s2, calcining the mixed powder in the step S1 in air; s3, the calcined powder obtained in the S2 is evenly mixed with conductive phase micro powder, a sintering aid and a solvent, obtained slurry is dried, and the conductive phase micro powder comprises one of molybdenum disilicide, titanium disilicide, chromium disilicide, zirconium disilicide and titanium carbide powder; and granulating, carrying out compression molding, drying and sintering to obtain the ZTA-based conductive ceramic composite material. The functional characteristics (electric conduction and heat conduction) are pursued, and meanwhile, the comprehensive mechanical property of the material is considered. The ZTA matrix provides high strength and toughness, the introduction of the mullite phase further strengthens the grain boundary, and the finally obtained ceramic composite material has the advantages of compact structure, high strength, good wear resistance and good thermal shock resistance, and can meet the comprehensive performance requirements of structural function integrated components.

Description

Technical Field

[0001] This invention relates to the field of ceramics, and more particularly to a ZTA-based conductive ceramic composite material, its preparation method, and its application. Background Technology

[0002] In high-temperature industrial applications, such as molten metal electrodes, high-temperature heating elements (>1000 °C), solid oxide fuel cell (SOFC) connectors, high-temperature sensors, and certain special electrovacuum devices, there is an urgent need for ceramic materials that can operate stably for extended periods in extreme high-temperature environments (>800 °C, or even >1500 °C) and possess excellent electrical conductivity (low resistivity). These materials must meet the following requirements:

[0003] 1) High-temperature conductivity stability; resistivity changes little or remains low as temperature increases.

[0004] 2) Excellent high-temperature stability, including oxidation resistance (especially in air or corrosive atmospheres), thermal shock resistance, low volatility and structural phase stability;

[0005] 3) Sufficient mechanical strength and durability. However, existing high-temperature conductive ceramic systems all face significant challenges.

[0006] Currently, high-temperature conductive ceramics mainly seek a balance through the following material systems and modification strategies, but significant limitations still exist:

[0007] 1) Oxide-based conductive ceramics, such as calcium lanthanum chromate (La) 1-X Ca X CrO3-based ceramics, these perovskite-structured oxides, are leading candidates for SOFC linkers. They are synthesized through Ca... 2+ When doped into an air atmosphere, it forms a p-type conductor (hole conduction), with a resistivity of approximately 10⁻⁶ at 800–1000 °C. -2 ~ 10 -1 Ω·cm; its main advantage lies in its excellent high-temperature oxidation stability. However, its bottleneck is insufficient absolute conductivity, making it difficult to meet the requirements of high-current applications (<10 Ω·cm). -2 Problems such as Ω·cm difficulty;

[0008] 2) Tin oxide (SnO2) doped ceramics, mainly utilizing Sb 5+ Ta 5+ Donor doping yields n-type conductivity, exhibiting low resistivity (<10 Ω·cm) at room temperature. -3However, its application at high temperatures (>800 °C) is limited, as its conductivity decreases significantly at high temperatures. This is due to changes in oxygen vacancy concentration and a sharp increase in grain boundary resistance. Furthermore, there is a high-temperature phase transition, from rutile to orthorhombic phase, accompanied by volume changes that lead to cracking.

[0009] 3) Carbide / boride / silicide-based high-temperature ceramics, such as titanium carbide / zirconium carbide (TiC, ZrC) ceramics. These materials have high melting points (>3000 °C), high hardness, and intrinsic metallic conductivity (resistivity of 10 at room temperature). -6 ~ 10 -5 (Ω·cm). However, its application in high-temperature oxidizing environments faces fatal flaws: a) Severe oxidation: It rapidly oxidizes in air at >500 °C to form a loose TiO2 or ZrO2 layer, which causes a sharp increase in resistivity and leads to pulverization failure; b) Pure phase sintering is difficult, and sintering aids (such as metallic Ni and Co) are often required, but the latter reduces high-temperature strength and accelerates oxidation.

[0010] 4) Molybdenum disilicide (MoSi2) ceramic: Currently the most mature high-temperature heating element material. Its advantages include: a) excellent high-temperature oxidation resistance (forms a protective SiO2 glass film in air at <1700°C); b) good electrical conductivity (room temperature resistivity of 10 Ω·cm). -5 (Ω·cm). However, these materials also have serious drawbacks, such as: a) severe creep deformation at high temperatures (>1200 °C), leading to dimensional instability or breakage of components; b) oxidation to form powdery MO3 within a specific temperature range (approximately 600 ~ 900 °C), resulting in powdering failure.

[0011] 5) Metal-ceramic composites: such as refractory metal-ceramic systems (e.g., Mo-ZrO2, W-HfO2). Currently, the main approach is to combine high-melting-point metals (Mo, W) with stable oxides (e.g., Y2O3-stabilized ZrO2, YSZ), attempting to combine the electrical conductivity of metals with the oxidation / thermal shock resistance of ceramics. The metal phase provides the conductive network (resistivity can approach that of pure metals, such as 10). -6 (on the order of Ω·cm). However, studies have shown that this approach has the following problems: a) the metallic phase is easily oxidized at high temperatures; b) at high temperatures, diffusion reactions easily occur at the metal / ceramic interface, forming a high-resistivity layer or leading to structural degradation; c) increasing the ceramic phase content enhances oxidation resistance but drastically increases resistivity; and vice versa.

[0012] Chinese patent application CN115124326B discloses a method for preparing a mesh-like TiC / ZTA conductive ceramic composite material. The specific steps are as follows: 1) Weigh a certain amount of solvent selected from anhydrous ethanol, dichloromethane, and ethyl acetate, and stir; 2) Weigh a certain amount of TiC powder and slowly add it to the solvent; continue stirring; 3) Impregnate ZTA granulated powder with the well-dispersed TiC slurry, with a mass ratio of ZTA powder to TiC slurry of 1:1, to obtain a TiC / ZTA composite powder slurry; 4) Dry the TiC / ZTA composite powder slurry, crush it, and obtain TiC / ZTA composite powder; 5) Fill the TiC / ZTA composite powder into a mold to form a strip-shaped green body; 6) Dry the green body to remove moisture, and then perform pressureless sintering. The pressureless sintering heating rate is 5℃ / min, the protective atmosphere is argon, the sintering temperature is 1650 ± 10℃, and the holding time is 2h. After ±10 min, a network-like TiC / ZTA conductive composite ceramic sample was obtained. This method has a more complex formulation (requiring the addition of solvents such as dichloromethane or ethyl acetate to prepare the slurry), and the process differs significantly from that of this application (e.g., impregnating ZTA granulated powder with TiC slurry). From a performance perspective, this method does not consider the matching of the materials' coefficients of thermal expansion. ZTA is zirconia-toughened alumina. Summary of the Invention

[0013] This invention aims to provide a ZTA-based conductive ceramic composite material, its preparation method, and its application, which, while pursuing functional properties (electrical conductivity and thermal conductivity), also takes into account the comprehensive mechanical properties of the material.

[0014] The present invention also provides an application of ZTA-based conductive ceramic composite material in high-temperature electrodes, heating elements, and thermal shock resistant components.

[0015] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0016] A method for preparing a ZTA-based conductive ceramic composite material includes the following steps:

[0017] S1. ZTA micro powder and a coefficient of thermal expansion regulator are dry-mixed to obtain a mixed powder, wherein the coefficient of thermal expansion regulator has an expansion coefficient of 5.0 × 10⁻⁶. -6 ~ 5.5×10 -6 / ℃;

[0018] S2. Calcine the mixed powder from S1 in air to obtain calcined powder;

[0019] S3. The calcined powder obtained in S2 is mixed evenly with conductive phase micro powder, sintering aid and solvent to obtain a slurry, which is then dried to obtain dried powder. The conductive phase micro powder includes one of molybdenum disilicide, titanium disilicide, chromium disilicide, zirconium disilicide and titanium carbide powder.

[0020] S4. Granulate the dried powder obtained in S3 to obtain granulated powder;

[0021] S5. The granulated powder obtained in S4 is molded into a green body and dried to obtain a dried green body.

[0022] S6. The green body dried in S5 is sintered under an inert atmosphere to obtain ZTA-based conductive ceramic composite material.

[0023] This invention first incorporates a ZTA matrix and a conductive phase, and introduces mullite as a coefficient of thermal expansion modifier, achieving a good match between the coefficients of thermal expansion of the various phases in the multiphase system. This design fundamentally reduces the thermal stress generated during rapid heating and cooling of the material, significantly improving its thermal shock resistance and enabling it to withstand harsh rapid thermal cycling conditions. Secondly, while taking into account functional properties (electrical and thermal conductivity), the ZTA matrix provides inherent high strength and toughness, and the mullite phase further strengthens the grain boundaries, resulting in a dense, high-strength, and wear-resistant ceramic composite material that meets the mechanical strength requirements of an integrated structural and functional component.

[0024] The ceramic composite material obtained by this invention has good electrical conductivity, good thermal conductivity, excellent mechanical properties and oxidation resistance. By selecting different conductive phase materials (including molybdenum disilicide / titanium disilicide / chromium disilicide / zirconium disilicide / titanium carbide), ceramic composite materials with different electrical conductivity and oxidation resistance can be obtained.

[0025] When the conductive phase is molybdenum disilicide and the addition amount is 40%, the resistivity of the ceramic composite material is 2.885 × 10⁻⁶. -3 Its strength is Ω·cm, thermal conductivity is 23.3 W / (m·K), Vickers hardness is 816.7 HV, flexural strength is 398.2 MPa, and fracture toughness is 3.7 MPa·m. 1 / 2 ;

[0026] When the conductive phase is titanium disilicide and the addition amount is 40%, the resistivity of the ceramic composite material is 4.585 × 10⁻⁶. -3 Its strength is Ω·cm, thermal conductivity is 16.3 W / (m·K), Vickers hardness is 723.1 HV, flexural strength is 325.3 MPa, and fracture toughness is 3.1 MPa·m. 1 / 2 ;

[0027] When the conductive phase is chromium disilicide and the addition amount is 40%, the resistivity of the ceramic composite material is 8.575 × 10⁻⁶. Its strength is Ω·cm, thermal conductivity is 11.1 W / (m·K), Vickers hardness is 765.2 HV, flexural strength is 318.4 MPa, and fracture toughness is 3.5 MPa·m. 1 / 2 ;

[0028] When the conductive phase is zirconium disilicide and the addition amount is 40%, the resistivity of the ceramic composite material is 6.885 × 10⁻⁶. 8 Its strength is Ω·cm, thermal conductivity is 9.2 W / (m·K), Vickers hardness is 634.2 HV, flexural strength is 212.6 MPa, and fracture toughness is 2.1 MPa·m. 1 / 2 ;

[0029] When the conductive phase is titanium carbide and the addition amount is 40%, the resistivity of the ceramic composite material is 4.402 × 10⁻⁶. -4 Its strength is Ω·cm, thermal conductivity is 12.2 W / (m·K), Vickers hardness is 644.2 HV, flexural strength is 209.4 MPa, and fracture toughness is 2.3 MPa·m. 1 / 2 .

[0030] According to embodiments of the present invention, the present invention can be further optimized, and the optimized technical solution is as follows:

[0031] In step S3, the conductive phase powder is molybdenum disilicide.

[0032] In one preferred embodiment, in step S3, the mass ratio of the calcined powder, the conductive phase micro powder, and the sintering aid is (50~80): (20~50): (1~3); preferably, the mass ratio of the calcined powder, the conductive phase micro powder, and the sintering aid is (50-70): (30-50): (1~3); more preferably, the mass ratio of the calcined powder, the conductive phase micro powder, and the sintering aid is (50~60): (40~50): (1~3).

[0033] Precisely controlling the ratio of ZTA matrix to conductive phase brings significant synergistic advantages to this invention: First, it achieves a functional breakthrough by constructing an effective conductive network in the matrix, thus solving the technical bottleneck of intrinsic insulation in ZTA ceramics and endowing the material with controllable electrical and thermal conductivity. Second, it ensures the preservation of mechanical properties by ensuring that the conductive phase exists in the minimum necessary amount, maximizing the preservation of the inherent advantages of ZTA matrix in terms of high hardness, high wear resistance, and high strength. Finally, it achieves a balance and synergy between mechanical, thermal, and electrical properties, successfully preparing a structurally and functionally integrated ceramic component that can both withstand mechanical stress and conduct current and dissipate heat, greatly expanding its application fields.

[0034] In one preferred embodiment, in step S1, the coefficient of thermal expansion regulator is mullite powder, and the mass ratio of ZTA powder to mullite powder is (2-8):1; preferably, the mass ratio of ZTA powder to mullite powder is (4-6):1; more preferably, the mass ratio of ZTA powder to mullite powder is (4.5-5.5):1.

[0035] In one preferred embodiment, in step S2, the sintering aid is titanium dioxide micro powder.

[0036] In one preferred embodiment, in step S2, the calcination temperature is 800 ~ 1200 ℃ and the holding time is 1 ~ 5 h; preferably, in S2, the calcination temperature is 950 ~ 1050 ℃ and the holding time is 2 ~ 4 h.

[0037] First, ZTA micro powder and mullite micro powder are uniformly mixed and calcined in air. The core purpose of this step is to achieve pre-bonding at the interface of the two phases, forming a structurally stable composite matrix. This operation not only effectively avoids internal stress and microscopic defects caused by phase expansion mismatch during subsequent high-temperature sintering, creating conditions for obtaining a high-density microstructure; secondly, this pre-bonded structure strengthens the grain boundaries of the final product, enabling the ceramic to maintain the high strength and wear resistance of the ZTA matrix while further enhancing its thermal shock resistance and overall mechanical strength, thus meeting the stringent requirements for the comprehensive performance of materials in structurally integrated components.

[0038] In one preferred embodiment, in step S3, the solvent is anhydrous ethanol, the mixing is performed by ball milling, the ball milling uses grinding balls of 1-3 mm, the weight ratio of powder to grinding balls to anhydrous ethanol is 1-2:1-2:1-2, the ball milling time is 4-10 h, and the ball mill speed is 300-400 r·min. -1Preferably, the ball milling time is 6 to 8 hours.

[0039] In one preferred embodiment, in step S6, the sintering heating process is performed at a rate of 1 to 6 °C / min. -1 The sintering temperature is 1400 ~ 1700 ℃, and the holding time is 1 ~ 8 h; preferably, the heating process of S6 is: the rate is 1 ~ 3 ℃·min -1 The sintering temperature is 1550 ~ 1650 ℃, and the holding time is 2 ~ 5 h.

[0040] The sintering temperature should be controlled within an appropriate range to achieve material densification and the formation of an excellent conductive network. Simultaneously, this measure effectively prevents abnormal ZTA grain growth, conductive phase volatilization or decomposition, and harmful interfacial reactions caused by excessively high temperatures, thus ensuring that the ceramic composite material possesses both excellent mechanical properties and stable electrical conductivity.

[0041] In step S1, the dry mixing temperature is 50-70℃, and the drying time is 24-36 h. In S1, the powder is ground in a mortar and pestle and sieved through an 80-mesh sieve, and this process is repeated 5-10 times.

[0042] In step S3, the conductive phase micro powder and titanium dioxide micro powder have a purity of 99.99% and a particle size D. 50 The thickness is 0.5 ~ 2 μm.

[0043] In step S3, the drying temperature is 60~80℃. o C, the drying time is 10~30h.

[0044] In step S3, the dried powder is sieved with a sieve mesh size of 70-90 mesh.

[0045] In step S4, 5-20 wt% of binder is added to the dried powder obtained in S3 and then sieved to obtain granulated powder. The granulated powder has good flowability. Preferably, the proportion of binder is 10-15 wt% and the granulated powder is 80-100 mesh.

[0046] In step S5, the compression molding is dry pressing. Preferably, dry pressing is performed first, followed by cold isostatic pressing. The pressure range of dry pressing or cold isostatic pressing is 30-300 MPa; preferably, the pressure range is 50-100 MPa.

[0047] In step S5, the drying temperature is 70~90°C. o C, the drying time is 10~30h.

[0048] The present invention also discloses a ZTA-based conductive ceramic composite material with a resistivity of 1.028 × 10⁻⁶. -4 ~ 4.0 ×10 8 Its electrical properties are: Ω·cm, thermal conductivity 9.2 ~ 25 W / (m·K), Vickers hardness 634.2 ~ 951.8 HV, flexural strength 209.4 ~ 430 MPa, and fracture toughness 2.1 ~ 4.3 MPa·m. 1 / 2 ;

[0049] Preferably, the resistivity is 1.028 × 10⁻⁶. -4 ~ 4.035 × 10 8 Its properties include: Ω·cm, thermal conductivity of 15 ~ 25 W / (m·K), Vickers hardness of 700 ~ 951.8 HV, flexural strength of 370.4 ~ 421.5 MPa, and fracture toughness of 3.2 ~ 4.3 MPa·m. 1 / 2 ;

[0050] More preferably, the resistivity is 1.028 × 10⁻⁶. -4 ~ 2.885×10 -3 Its electrical properties are: Ω·cm, thermal conductivity 20 ~ 25 W / (m·K), Vickers hardness 700 ~ 816.7 HV, flexural strength 370.4 ~ 398.2 MPa, and fracture toughness 3.2 ~ 3.7 MPa·m. 1 / 2 .

[0051] The present invention also discloses a ZTA-based conductive ceramic composite material prepared according to the preparation method described above, or the application of the ZTA-based conductive ceramic composite material as described above in high-temperature electrodes, heating elements, and thermal shock resistant components.

[0052] Therefore, this application shifts from "single-structure multiphase material" to "structure-function integrated multiphase material". By introducing a conductive phase, the material system and properties are richer and the application prospects are broader. Furthermore, in terms of process, the pre-calcination step enhances the interfacial bonding between ZTA and mullite, which can significantly improve the thermal shock resistance of ceramic composite materials.

[0053] Compared with the prior art, the beneficial effects of the present invention are:

[0054] This invention first incorporates a ZTA matrix and a conductive phase, and introduces mullite as a coefficient of thermal expansion modifier, achieving a good match between the coefficients of thermal expansion of the various phases in the multiphase system. Furthermore, by precisely controlling the ratio of the ZTA matrix to the conductive phase and introducing a specific proportion of mullite as a coefficient of thermal expansion modifier, this invention achieves a good match between the coefficients of thermal expansion of the various phases in the composite system, thereby fundamentally reducing the thermal stress of the material during rapid heating and cooling, significantly improving its thermal shock resistance, and enabling it to withstand harsh rapid thermal cycling conditions. Simultaneously, this invention, while endowing the ceramic composite material with electrical and thermal conductivity, synergistically optimizes its comprehensive mechanical properties. The ZTA matrix provides inherent high strength and toughness, while the introduction of the mullite phase further strengthens the grain boundaries, resulting in a dense ceramic composite material with high strength and high wear resistance, meeting the mechanical strength requirements of an integrated structural and functional component.

[0055] The ceramic composite materials prepared by this process have a scientifically designed composition and excellent balanced performance. Furthermore, the preparation process is simple and requires minimal equipment, offering both practicality and significant technological advantages, making it suitable for mass industrial production. This technology shows broad application prospects in fields requiring rapid thermal cycling, such as high-temperature electrodes, heating elements, and thermal shock resistant components. Attached Figure Description

[0056] Figure 1 The XRD pattern of the sample obtained in Example 1;

[0057] Figure 2 SEM images of the samples obtained in Example 1;

[0058] Figure 3 The XRD pattern of the sample obtained in Example 2;

[0059] Figure 4 SEM images of the samples obtained in Example 2;

[0060] Figure 5 The XRD pattern of the sample obtained in Example 3;

[0061] Figure 6 SEM images of the samples obtained in Example 3;

[0062] Figure 7 The XRD pattern of the sample obtained in Example 4;

[0063] Figure 8 SEM images of the samples obtained in Example 4;

[0064] Figure 9 The XRD pattern of the sample obtained in Example 5;

[0065] Figure 10 SEM images of the samples obtained in Example 5;

[0066] Figure 11 The XRD pattern of the sample obtained in Example 6;

[0067] Figure 12 SEM images of the samples obtained in Example 6;

[0068] Figure 13 The XRD pattern of the sample obtained in Example 7;

[0069] Figure 14 SEM images of the samples obtained in Example 7;

[0070] Figure 15 The XRD pattern of the sample obtained in Example 8;

[0071] Figure 16 This is a SEM image of the sample obtained in Example 8. Detailed Implementation

[0072] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0073] Example 1

[0074] ZTA micro powder and mullite micro powder were dry-mixed at a mass ratio of 5:1 at 60 ℃ for 24 h. The powder was then ground in a mortar and sieved through an 80-mesh sieve, repeated 8 times. The mixture was then calcined in air at 1000 ℃ for 3 h to obtain calcined powder. 80 g of the calcined powder, 20 g of molybdenum disilicide micro powder, and 2.0 g of titanium dioxide micro powder were placed in a ball mill jar, and anhydrous ethanol was added. The grinding balls were 1 mm Al₂O₃ balls, with a material:ball:anhydrous ethanol ratio of 1:2:1-2 (mass ratio). The ball mill speed was 300 r·min. -1 Ball milling for 6 hours, followed by drying the resulting suspension in an oven at 60 °C for 24 hours to obtain a mixed powder. This powder was then sieved to obtain a mixed ceramic powder with an 80-mesh sieve. After adding 10 wt% PVA binder, the powder was sieved again to obtain granulated powder. This granulated powder was then molded under 70 MPa pressure to obtain a ceramic green body, and further processed at 80 °C. o Dry at C for 24 h. The resulting ceramic green body was then sintered at 1650 °C in a high-temperature tube furnace under an argon atmosphere to obtain a dense ceramic composite material. The sintering temperature rise rate was 3 °C / min. -1 The heat preservation time is 3 hours.

[0075] The resistivity of the obtained ceramic composite material is 4.305 × 10⁻⁶. 8 Its strength is Ω·cm, thermal conductivity is 16.5 W / (m·K), Vickers hardness is 915.8 HV, flexural strength is 421.5 MPa, and fracture toughness is 4.3 MPa·m. 1 / 2 .

[0076] Example 2

[0077] A calcined powder was obtained by calcining ZTA micro powder and mullite micro powder at a mass ratio of 5:1, at a calcination temperature of 1000℃, and a holding time of 3 hours. 70 g of the calcined powder, 30 g of molybdenum disilicide micro powder, and 2.0 g of titanium dioxide micro powder were weighed and placed in a ball mill jar. Anhydrous ethanol was added. The grinding balls were 1 mm Al₂O₃ balls, and the material:ball:anhydrous ethanol ratio was 1:2:1-2 (mass ratio). The ball mill speed was 300 r·min. -1 The mixture was ball-milled for 6 hours, and the resulting suspension was dried in an oven at 60 °C for 24 hours to obtain a mixed powder. This powder was then sieved to obtain a mixed ceramic powder with a sieve mesh size of 80 mesh. After adding 10 wt% PVA binder, the powder was sieved again to obtain granulated powder. This granulated powder was then molded under a pressure of 70 MPa to obtain a ceramic green body. The resulting ceramic green body was then sintered in a high-temperature tube furnace at 1650 °C under an argon atmosphere to obtain a dense ceramic composite material.

[0078] The resistivity of the obtained ceramic composite material is 4.575 × 10⁻⁶. 6 Its strength is Ω·cm, thermal conductivity is 18.7 W / (m·K), Vickers hardness is 865.4 HV, flexural strength is 401.6 MPa, and fracture toughness is 3.9 MPa·m. 1 / 2 .

[0079] Example 3

[0080] A calcined powder was obtained by calcining ZTA micro powder and mullite micro powder at a mass ratio of 5:1, at a calcination temperature of 1000℃, and a holding time of 3 hours. 60 g of the calcined powder, 40 g of molybdenum disilicide micro powder, and 2.0 g of titanium dioxide micro powder were weighed and placed in a ball mill jar. Anhydrous ethanol was added. The grinding balls were 1 mm Al₂O₃ balls, and the material:ball:anhydrous ethanol ratio was 1:2:1-2 (mass ratio). The ball mill speed was 300 r·min. -1 The mixture was ball-milled for 6 hours, and the resulting suspension was dried in an oven at 60 °C for 24 hours to obtain a mixed powder. This powder was then sieved to obtain a mixed ceramic powder with a sieve mesh size of 80 mesh. After adding 10 wt% PVA binder, the powder was sieved again to obtain granulated powder. This granulated powder was then molded under a pressure of 70 MPa to obtain a ceramic green body. The resulting ceramic green body was then sintered in a high-temperature tube furnace at 1650 °C under an argon atmosphere to obtain a dense ceramic composite material.

[0081] The resistivity of the obtained ceramic composite material is 2.885 × 10⁻⁶. -3 Its strength is Ω·cm, thermal conductivity is 23.3 W / (m·K), Vickers hardness is 816.7 HV, flexural strength is 398.2 MPa, and fracture toughness is 3.7 MPa·m. 1 / 2 .

[0082] Example 4

[0083] The ZTA micro powder and mullite micro powder were calcined at a mass ratio of 5:1 at 1000℃ for 3 hours to obtain calcined powder. 50 g of the calcined powder, 50 g of molybdenum disilicide micro powder, and 2.0 g of titanium dioxide micro powder were placed in a ball mill jar, and anhydrous ethanol was added. The grinding balls were 1 mm Al₂O₃ balls, and the material:ball:anhydrous ethanol ratio was 1:2:1-2 (mass ratio). The ball mill speed was 300 r·min. -1 The mixture was ball-milled for 6 hours, and the resulting suspension was dried in an oven at 60 °C for 24 hours to obtain a mixed powder. This powder was then sieved to obtain a mixed ceramic powder with a mesh size of 80 mesh. After adding 10 wt% PVA binder, the powder was sieved again to obtain granulated powder. This granulated powder was then molded under a pressure of 70 MPa to obtain a ceramic green body. The resulting ceramic green body was then sintered in a high-temperature tube furnace at 1650 °C under an argon atmosphere to obtain a dense ceramic composite material.

[0084] The resistivity of the obtained ceramic composite material is 1.028 × 10⁻⁶. -4 Its strength is Ω·cm, thermal conductivity is 23.7 W / (m·K), Vickers hardness is 736.9 HV, flexural strength is 370.4 MPa, and fracture toughness is 3.2 MPa·m. 1 / 2 .

[0085] Example 5

[0086] The difference between this embodiment and Embodiment 3 lies in the different conductive phase materials.

[0087] A calcined powder was obtained by calcining ZTA micro powder and mullite micro powder at a mass ratio of 5:1, at a calcination temperature of 1000℃, and a holding time of 3 hours. 60 g of the calcined powder, 40 g of titanium disilicide micro powder, and 2.0 g of titanium dioxide micro powder were weighed and placed in a ball mill jar. Anhydrous ethanol was added. The grinding balls were 1 mm Al₂O₃ balls, and the material:ball:anhydrous ethanol ratio was 1:2:1-2 (mass ratio). The ball mill speed was 300 r·min. -1The mixture was ball-milled for 6 hours, and the resulting suspension was dried in an oven at 60 °C for 24 hours to obtain a mixed powder. This powder was then sieved to obtain a mixed ceramic powder with a sieve mesh size of 80 mesh. After adding 10 wt% PVA binder, the powder was sieved again to obtain granulated powder. This granulated powder was then molded under a pressure of 70 MPa to obtain a ceramic green body. The resulting ceramic green body was then sintered in a high-temperature tube furnace at 1650 °C under an argon atmosphere to obtain a dense ceramic composite material.

[0088] The resistivity of the obtained ceramic composite material is 4.585 × 10⁻⁶. -3 Its strength is Ω·cm, thermal conductivity is 16.3 W / (m·K), Vickers hardness is 732.1 HV, flexural strength is 325.3 MPa, and fracture toughness is 3.1 MPa·m. 1 / 2 .

[0089] Example 6

[0090] The difference between this embodiment and Embodiment 3 lies in the different conductive phase materials.

[0091] A calcined powder was obtained by calcining ZTA micro powder and mullite micro powder at a mass ratio of 5:1, at a calcination temperature of 1000℃, and a holding time of 3 hours. 60 g of the calcined powder, 40 g of chromium disilicide micro powder, and 2.0 g of titanium dioxide micro powder were weighed and placed in a ball mill jar. Anhydrous ethanol was added. The grinding balls were 1 mm Al₂O₃ balls, and the material:ball:anhydrous ethanol ratio was 1:2:1-2 (mass ratio). The ball mill speed was 300 r·min. -1 The mixture was ball-milled for 6 hours, and the resulting suspension was dried in an oven at 60 °C for 24 hours to obtain a mixed powder. This powder was then sieved to obtain a mixed ceramic powder with a mesh size of 80 mesh. After adding 10 wt% PVA binder, the powder was sieved again to obtain granulated powder. This granulated powder was then molded under a pressure of 70 MPa to obtain a ceramic green body. The resulting ceramic green body was then sintered in a high-temperature tube furnace at 1650 °C under an argon atmosphere to obtain a dense ceramic composite material.

[0092] The resistivity of the obtained ceramic composite material is 8.575 × 10⁻⁶. Its strength is Ω·cm, thermal conductivity is 11.1 W / (m·K), Vickers hardness is 765.2 HV, flexural strength is 318.4 MPa, and fracture toughness is 3.5 MPa·m. 1 / 2 .

[0093] Example 7

[0094] The difference between this embodiment and Embodiment 3 lies in the different conductive phase materials.

[0095] A calcined powder was obtained by calcining zirconium disilicide (ZTA) micropowder and mullite micropowder at a mass ratio of 5:1, calcining temperature of 1000℃, and holding time of 3h. 60 g of the calcined powder, 40 g of zirconium disilicide micropowder, and 2.0 g of titanium dioxide micropowder were weighed and placed in a ball mill jar. Anhydrous ethanol was added. The grinding balls were 1 mm Al₂O₃ balls, and the material:ball:anhydrous ethanol ratio was 1:2:1-2 (mass ratio). The ball mill speed was 300 r·min. -1 The mixture was ball-milled for 6 hours, and the resulting suspension was dried in an oven at 60 °C for 24 hours to obtain a mixed powder. This powder was then sieved to obtain a mixed ceramic powder with a mesh size of 80 mesh. After adding 10 wt% PVA binder, the powder was sieved again to obtain granulated powder. This granulated powder was then molded under a pressure of 70 MPa to obtain a ceramic green body. The resulting ceramic green body was then sintered in a high-temperature tube furnace at 1650 °C under an argon atmosphere to obtain a dense ceramic composite material.

[0096] The resistivity of the obtained ceramic composite material is 6.885 × 10⁻⁶. -2 Its strength is Ω·cm, thermal conductivity is 9.2 W / (m·K), Vickers hardness is 634.2 HV, flexural strength is 212.6 MPa, and fracture toughness is 2.1 MPa·m. 1 / 2 .

[0097] Example 8

[0098] The difference between this embodiment and Embodiment 3 lies in the different conductive phase materials.

[0099] A calcined powder was obtained by calcining ZTA micro powder and mullite micro powder at a mass ratio of 5:1, at a calcination temperature of 1000℃, and a holding time of 3 hours. 60 g of the calcined powder, 40 g of titanium carbide micro powder, and 2.0 g of titanium dioxide micro powder were weighed and placed in a ball mill jar. Anhydrous ethanol was added. The grinding balls were 1 mm Al₂O₃ balls, and the material:ball:anhydrous ethanol ratio was 1:2:1-2 (mass ratio). The ball mill speed was 300 r·min. -1 The mixture was ball-milled for 6 hours, and the resulting suspension was dried in an oven at 60 °C for 24 hours to obtain a mixed powder. This powder was then sieved to obtain a mixed ceramic powder with a mesh size of 80 mesh. After adding 10 wt% PVA binder, the powder was sieved again to obtain granulated powder. This granulated powder was then molded under a pressure of 70 MPa to obtain a ceramic green body. The resulting ceramic green body was then sintered in a high-temperature tube furnace at 1650 °C under an argon atmosphere to obtain a dense ceramic composite material.

[0100] The resistivity of the obtained ceramic composite material is 4.402 × 10⁻⁶. -4 Its strength is Ω·cm, thermal conductivity is 12.2 W / (m·K), Vickers hardness is 644.2 HV, flexural strength is 209.4 MPa, and fracture toughness is 2.3 MPa·m. 1 / 2.

[0101] The composition of the ceramic composite materials prepared in the comparative examples and embodiments is shown in Table 1, and the test results of resistivity and thermal conductivity are shown in Table 2.

[0102] Table 1. Composition of ceramic composite materials prepared in comparative examples and embodiments.

[0103]

[0104] Table 2. Statistical table of test results for ceramic composite materials prepared in comparative examples and embodiments.

[0105]

[0106] Referring to Table 1, the examples using molybdenum disilicide as the conductive phase exhibit comprehensive and superior overall performance. As its content increases from 20% to 50%, a series of key transformations occur in the ceramic composite material. The resistivity increases from 10... 8 The order of magnitude of Ω·cm drops sharply to 10 -4 The concentration drops to the order of Ω·cm, spanning more than 12 orders of magnitude. This nonlinear drop, especially in the 30%-40% content range, typically conforms to the penetration threshold theory: when the content of conductive particles reaches a critical value, a three-dimensional interconnected conductive network forms inside the material, thus achieving the transformation from an insulator to a good conductor. Simultaneously, the thermal conductivity steadily increases from 16.5 W / (m·K) to 23.7 W / (m·K), thanks to the high thermal conductivity of molybdenum disilicide itself and the effective heat conduction pathways it forms. More notably, the sintering shrinkage of the system remained consistently in the relatively high range of 15.96%-17.56%, which strongly demonstrates the excellent physicochemical compatibility between molybdenum disilicide and the ZTA / mullite matrix, enabling them to synergistically promote the sintering densification process. Although the Vickers hardness decreased with increasing conductive phase content, it still reached 816.7 HV at the optimal comprehensive performance level of 40% content (Example 3), significantly higher than the level of other conductive phases at the same content, proving that the introduction of MoSi2 did not come at the cost of severely sacrificing the mechanical strength of the material.

[0107] Compared to Examples 5-8 which used other conductive phases, molybdenum disilicide exhibits more significant advantages. While titanium carbide (Example 8) can reduce resistivity to approximately 10... -4 While its resistivity is Ω·cm, its thermal conductivity (12.2 W / (m·K)) is significantly low, its shrinkage rate (10.26%) is insufficient, and its Vickers hardness (644.2 HV) is low, indicating poor bonding with the matrix and severely impairing the density and mechanical integrity of the structure. In contrast, chromium disilicide (Example 6) has a higher resistivity of 8.575 × 10⁻⁶ Ω·cm. The thermal conductivity (Ω·cm) failed to effectively construct a conductive pathway. All comparative examples showed lower thermal conductivity, shrinkage, and Vickers hardness than the MoSi2 system. This reveals that other conductive phases, due to insufficient thermal conductivity and weak interfacial bonding, are not conducive to sintering densification and cannot maintain the inherent high hardness of ceramic composites.

[0108] In summary, molybdenum disilicide has proven to be an ideal conductive phase choice in the ZTA / mullite-based composite material system designed in this study. It not only imparts excellent electrical and thermal conductivity when present at a certain content (recommended ≥ 40%), but also exhibits a good sintering synergistic effect with the matrix, ensuring the structural density and integrity of the resulting material.

[0109] The applicant declares that the present invention is illustrated through the above embodiments to demonstrate its detailed features and methods, but the present invention includes, but is not limited to, the detailed features and methods described above. Those skilled in the art should understand that any non-essential modifications to the present invention, including but not limited to equivalent substitutions of raw materials, additives, and steps, fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a ZTA-based conductive ceramic composite material, characterized in that, Includes the following steps: S1. ZTA micro powder and a coefficient of thermal expansion regulator are dry-mixed to obtain a mixed powder, wherein the coefficient of thermal expansion regulator has an expansion coefficient of 5.0 × 10⁻⁶. -6 ~5.5×10 -6 / ℃; S2. Calcine the mixed powder in S1 in air to obtain calcined powder; S3. The calcined powder obtained in S2 is mixed evenly with conductive phase micro powder, sintering aid and solvent to obtain a slurry, which is then dried to obtain dried powder. The conductive phase micro powder includes one of molybdenum disilicide, titanium disilicide, chromium disilicide, zirconium disilicide and titanium carbide powder. S4. Granulate the dried powder obtained in S3 to obtain granulated powder; S5. The granulated powder obtained in S4 is molded into a green body and dried to obtain a dried green body. S6. The green body dried in S5 is sintered under an inert atmosphere to obtain ZTA-based conductive ceramic composite material.

2. The preparation method according to claim 1, characterized in that, In step S3, the conductive phase powder is molybdenum disilicide.

3. The preparation method according to claim 2, characterized in that, In step S3, the mass ratio of the calcined powder, the conductive phase micro powder, and the sintering aid is (50~80): (20~50): (1~3); preferably, the mass ratio of the calcined powder, the conductive phase micro powder, and the sintering aid is (50-70): (30-50): (1~3); more preferably, the mass ratio of the calcined powder, the conductive phase micro powder, and the sintering aid is (50~60): (40~50): (1~3).

4. The preparation method according to claim 1, characterized in that, In step S1, the thermal expansion coefficient regulator is mullite powder, and the mass ratio of ZTA powder to mullite powder is (2-8):1; preferably, the mass ratio of ZTA powder to mullite powder is (4-6):1; more preferably, the mass ratio of ZTA powder to mullite powder is (4.5-5.5):

1.

5. The preparation method according to claim 1, characterized in that, In step S2, the sintering aid is titanium dioxide micro powder.

6. The preparation method according to any one of claims 1-5, characterized in that, In step S2, the calcination temperature is 800 ~ 1200 ℃ and the holding time is 1 ~ 5 h; preferably, the calcination temperature in S2 is 950 ~ 1050 ℃ and the holding time is 2 ~ 4 h.

7. The preparation method according to any one of claims 1-5, characterized in that, In step S3, the solvent is anhydrous ethanol, the mixing is performed by ball milling, the ball milling uses grinding balls of 1-3 mm, the weight ratio of powder to grinding balls to anhydrous ethanol is 1-2:1-2:1-2, the ball milling time is 4-10 h, and the ball mill speed is 300-400 r·min. -1 Preferably, the ball milling time is 6 to 8 hours.

8. The preparation method according to any one of claims 1-5, characterized in that, In step S6, the sintering heating process is as follows: the heating rate is 1 ~ 6 ℃·min -1 The sintering temperature is 1400 ~ 1700 ℃, and the holding time is 1 ~ 8 h; preferably, the heating process of S6 is: the rate is 1 ~ 3 ℃·min -1 The sintering temperature is 1550 ~ 1650 ℃, and the holding time is 2 ~ 5 h.

9. A ZTA-based conductive ceramic composite material, characterized in that, The resistivity is 1.028 × 10⁻⁶ -4 ~ 5.0 × 10 8 Its electrical properties are: Ω·cm, thermal conductivity 9.2 ~ 25 W / (m·K), Vickers hardness 634.2 ~ 951.8 HV, flexural strength 209.4 ~ 430 MPa, and fracture toughness 2.1 ~ 4.3 MPa·m. 1 / 2 ; Preferably, the resistivity is 1.028 × 10⁻⁶. -4 ~ 4.035 × 10 8 Its properties include: Ω·cm, thermal conductivity of 15 ~ 25 W / (m·K), Vickers hardness of 700 ~ 951.8 HV, flexural strength of 370.4 ~ 421.5 MPa, and fracture toughness of 3.2 ~ 4.3 MPa·m. 1 / 2 ; More preferably, the resistivity is 1.028 × 10⁻⁶. -4 ~ 2.885×10 -3 Its properties include: Ω·cm, thermal conductivity of 20 ~ 25 W / (m·K), Vickers hardness of 700 ~ 816.7 HV, flexural strength of 370.4 ~ 398.2 MPa, and fracture toughness of 3.2 ~ 3.7 MPa·m. 1 / 2 .

10. A ZTA-based conductive ceramic composite material prepared by the preparation method according to any one of claims 1-8, or the application of the ZTA-based conductive ceramic composite material according to claim 9 in high-temperature electrodes, heating elements, and thermal shock resistant components.

Images