Multi-scale bionic structure composite ceramic material and preparation method thereof
Through the multi-scale synergistic toughening mechanism of nano-ZrO2 particles and bionic Bouligand structural layers, the brittleness problem of Al2O3-based ceramic materials is solved, high density and excellent hardness, fracture toughness and bending strength are achieved, and its application in cutting-edge technology fields is expanded.
Patent Information
- Application Number
- CN202510784865.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-12
- Publication Date
- 2025-09-16
AI Technical Summary
Al2O3-based ceramic materials are brittle and have low toughness due to the directionality and bonding strength of chemical bonds, which limits their application in cutting-edge technology fields. In addition, the problems of grain growth and carbon fiber strength loss during the sintering process of Cf/Al2O3-SiC-ZrO2 composite ceramic materials have not been effectively solved.
A multi-scale synergistic toughening mechanism of nano-ZrO2 particles and bionic Bouligand structural layers is adopted. By preparing bionic Bouligand structural layers and ceramic mixed powders and combining them with plasma sintering technology, a multi-angle Bouligand structure is formed to achieve fiber reinforcement and interface regulation, thereby improving the fracture toughness and flexural strength of the material.
The toughness and strength of Al2O3-based ceramic materials have been significantly improved, forming composite ceramic materials with high density, uniform grain distribution and clear grain boundaries, which are suitable for fields such as aerospace and nuclear industry.
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Figure CN120647406A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of composite ceramic materials, and in particular relates to a multi-scale bionic structure composite ceramic material and a preparation method thereof. Background Art
[0002] Al2O3-based ceramics are widely used in cutting-edge technologies such as mechanical engineering, chemical engineering, and aerospace due to their excellent chemical stability, high-temperature resistance, corrosion resistance, wear resistance, and low density. However, the chemical bonds in Al2O3 ceramics are primarily covalent and ionic, both of which have significant directionality and high bonding strength. These unique chemical bonds and characteristics make it difficult for them to produce sufficient dislocation motion under external forces. This intrinsic property makes Al2O3-based ceramics inherently brittle and exhibits low strength and toughness. These mechanical property deficiencies significantly restrict their practical application in cutting-edge technologies.
[0003] In recent years, with the continuous development of bionics, bionic structural design has provided new theoretical guidance for the design and preparation of high-performance ceramic materials, especially providing innovative ideas for solving the inherent brittleness problem of ceramic materials. The core principle of bionic structural design of ceramic materials based on energy dissipation mechanism is to reduce the sensitivity of the mechanical properties of materials to initial crack defects. This design method draws on and optimizes the excellent properties of natural biomaterials, which is different from traditional strengthening and toughening methods such as nanoparticle toughening, whisker toughening, fiber toughening, and phase change toughening. Traditional methods usually improve toughness at the expense of some strength, while bionic structural design can achieve a synergistic improvement in strength and toughness.
[0004] While current research on biomimetic structural ceramics has made significant progress in improving toughness, changes in the material's internal microstructure inevitably affect its overall density and strength, which to some extent restricts the practical application of biomimetic structures in ceramic materials. While various methods exist to improve the toughness of ceramic materials, simply optimizing the strength of the ceramic matrix at a single macroscopic or microscopic level is unlikely to fundamentally improve the inherent brittleness of ceramic materials.
[0005] C f The raw materials used in Al2O3-SiC-ZrO2 composite ceramic materials generally have high melting points and hardness, which can lead to sintering difficulties. Hot pressing sintering requires a long holding time, which can lead to excessive grain growth, resulting in a decrease in the mechanical properties of the sintered body. Prolonged high temperatures can also reduce the strength of the carbon fibers. Summary of the Invention
[0006] In response to the defects of the existing technology, the present invention provides a multi-scale bionic structure composite ceramic material and a preparation method thereof. Through the multi-scale synergistic toughening mechanism of nano-ZrO2 particles and bionic Bouligand structure layers, the toughness of Al2O3-based ceramic materials is greatly improved. The prepared composite ceramic material has excellent hardness, fracture toughness and flexural strength.
[0007] A method for preparing a multi-scale bionic structure composite ceramic material comprises the following steps: (1) Preparation of bionic Bouligand structure layer: (11) Add Al2O3 powder, SiC powder, and ZrO2 powder to LPCS and stir for 10-15 h to obtain LPCS ceramic slurry; (12) After soaking the carbon fiber bundle in acetone for 15-20 minutes, spread it on a polytetrafluoroethylene plate in the same direction, and then evenly apply the LPCS ceramic slurry on its surface. After standing at room temperature for 10-15 hours, dry it and cut it to obtain LPCS-C f / ceramic thin films; (13) Dissolve Al2O3 powder, SiC powder and ZrO2 powder in anhydrous ethanol and stir for 7-9 hours to obtain ceramic slurry solution; f / immersing the ceramic film in the ceramic slurry solution, taking it out and drying it to obtain a bionic Bouligand structure layer; (2) Preparation of ceramic mixed powder: Al2O3 powder, SiC powder, ZrO2 powder and MgO powder are mixed, anhydrous ethanol is added thereto, ultrasonically treated and stirred for 35-50 minutes, ball milled, vacuum dried, cooled and sieved to obtain a ceramic mixed powder; (3) Preparation of composite ceramic materials: (31) Ceramic mixed powder and bionic Bouligand structure layers are stacked alternately horizontally in a graphite mold, and the ceramic embryo body finally formed has the following structure: a bionic Bouligand structure layer is placed between each two adjacent layers of ceramic mixed powder, and the direction of the fiber bundles in the latter bionic Bouligand structure layer is arranged clockwise or counterclockwise relative to the direction of the fiber bundles in the previous bionic Bouligand structure layer in each two adjacent layers of bionic Bouligand structure layer; the diameter of the bionic Bouligand structure layer is 70-80% of the inner diameter of the graphite mold, and the diameter of the ceramic mixed powder layer formed by the ceramic mixed powder matches the inner diameter of the graphite mold; (32) After pressure molding, the pressure of the pressure molding is maintained to perform plasma sintering to obtain a composite ceramic material.
[0008] Preferably, in step (31), there are 5 layers of ceramic mixed powder and 4 layers of bionic Bouligand structure layers; in each two adjacent bionic Bouligand structure layers, the direction of the fiber bundles in the latter bionic Bouligand structure layer is arranged counterclockwise at 45° relative to the direction of the fiber bundles in the previous bionic Bouligand structure layer.
[0009] Preferably, the inner diameter of the graphite mold is 20 mm, corresponding to a weight of 1 g for each layer of the ceramic mixed powder.
[0010] Preferably, in step (11), the mass ratio of Al2O3 powder, SiC powder, ZrO2 powder and LPCS is (2.3-2.7): (1.9-2.3): (0.1-0.3): 1; the ratio of Al2O3 powder, SiC powder and ZrO2 powder in step (13) is the same as that in step (11), and in step (13), the volume ratio of the total volume of Al2O3 powder, SiC powder and ZrO2 powder to anhydrous ethanol is (2.8-3.2): 1; in step (2), ZrO2 powder and MgO powder account for 4.2%-4.8% and 0.4%-0.6% of the total volume of Al2O3 powder and SiC powder, respectively, and the volume ratio of Al2O3 powder to SiC powder is (2.8-3.2): 1.
[0011] Preferably, the plasma sintering adopts step-by-step sintering, wherein the first step is to heat up to 800°C at 100°C / min and keep warm for 1 hour; the second step is to heat up to 1600-1750°C at 100°C / min and keep warm for 4-13 minutes; the third step is to water cool to 700°C at 150°C / min and then cool to room temperature with the furnace, and the vacuum is maintained throughout the sintering process.
[0012] Preferably, in the plasma sintering, in the second step, the temperature is raised to 1700° C. at 100° C. / min and then kept at that temperature for 10 minutes.
[0013] Preferably, the particle sizes of the Al2O3 powder, SiC powder, ZrO2 powder and MgO powder are 0.5-1 μm, 0.5-1 μm, 20-30 nm and 0.5-1 μm respectively.
[0014] Preferably, the ball milling conditions are as follows: the ball milling tank is made of stainless steel, the ball milling medium is ZrO2, the ball-to-material ratio is 10:1, and the ball milling time is 12-24 h.
[0015] Preferably, the drying conditions in step (12) are drying at 150-180°C for 1-4 hours; the drying conditions in step (13) are drying at 40-45°C for 25-30 minutes; and the vacuum drying conditions in step (2) are vacuum degree <40 Pa, temperature 100-140°C, and drying time 3-4 hours.
[0016] Preferably, the carbon fiber bundle is a 12k carbon fiber bundle.
[0017] A multi-scale bionic structure composite ceramic material is prepared by any of the above preparation methods.
[0018] In the present invention, LPCS is liquid polycarbosilane.
[0019] Advantages of the present invention: (1) The present invention realizes a multi-scale synergistic toughening mechanism of nano-ZrO2 particles and bionic Bouligand structure layer by controlling the macrostructure design and microstructure (macro-level: four-layer multi-angle Bouligand structure; micro-level: nano-ZrO2 particle control). Nano-ZrO2 particles induce directional crack propagation through stress field control and the coupling effect of bionic Bouligand structure layer. The fracture toughness of the material is significantly improved through the synergistic effect of fiber reinforcement, interface control and multiple toughening mechanisms, thereby improving the overall performance of the material. (2) The composite ceramic material has high density, uniform grain distribution, clear grain boundaries and good interface bonding, and has excellent hardness, fracture toughness and bending strength, which makes it have wide application potential in cutting-edge technology fields such as aerospace and nuclear industry; (3) The present invention successfully constructed a four-layer bionic Bouligand structure system with characteristic angles of 0°, 45°, 90° and 135°. A complex interpenetrating network interface was formed between the ceramic matrix and the Bouligand structure layer through a plasma sintering process. This multi-angle Bouligand structure realizes the transformation of external load into multi-directional stress, providing multiple resistances to crack propagation. At the same time, the interlayer interface provides an energy absorption path, significantly improving the fracture toughness of the material. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 Schematic diagram of the structure of the ceramic body; Figure 2 This is a scanning electron microscope image of the composite ceramic material prepared in Examples 1-4; Figure 3 This is a scanning electron microscope image of a cross section of the composite ceramic material of Example 3; Figure 4These are scanning electron microscope images of cracks on the surface and side of the ceramic material of Example 3 and EDS energy spectrum analysis images at the inflection point of crack propagation. DETAILED DESCRIPTION
[0021] Example 1 The particle sizes of the raw materials Al2O3 powder, SiC powder, ZrO2 powder, and MgO powder used in this embodiment are 0.5 μm, 0.5 μm, 20 nm, and 0.5 μm, respectively; A method for preparing a multi-scale bionic structure composite ceramic material comprises the following steps: (1) Preparation of bionic Bouligand structure layer: (11) According to the mass ratio of Al2O3, SiC, ZrO2, and LPCS of 2.5:2.1:0.2:1, Al2O3 powder, SiC powder, and ZrO2 powder were added to LPCS and magnetically stirred for 12 h to obtain LPCS ceramic slurry; (12) After soaking the 12k carbon fiber bundle in acetone for 15 minutes, the bundle was spread on a polytetrafluoroethylene plate in the same direction. Then, the LPCS ceramic slurry was evenly brushed on the surface. After standing at room temperature for 12 hours, the bundle was dried at 170 °C for 2 hours and cut into original sheets with a diameter of 15 mm to obtain LPCS-C. f / ceramic thin films; (13) Al2O3 powder, SiC powder, and ZrO2 powder with a mass ratio of 2.5:2.1:0.2 were dissolved in anhydrous ethanol, wherein the volume ratio of the total volume of Al2O3 powder, SiC powder, and ZrO2 powder to anhydrous ethanol was 3:1, and stirred for 8 hours to obtain a ceramic slurry solution; the cut LPCS-C f / The ceramic film is immersed in the ceramic slurry solution, taken out and dried at 40° C. for 30 minutes to obtain a bionic Bouligand structure layer; (2) Preparation of ceramic mixed powder: Al2O3 powder, SiC powder, ZrO2 powder and MgO powder were mixed, anhydrous ethanol was added thereto, ultrasonically treated and stirred at a speed of 180 rpm for 40 minutes, and then ball milled, vacuum dried at a vacuum degree of 35 Pa and 140°C for 4 hours, and sieved with a 100-mesh sieve after cooling to obtain a ceramic mixed powder; wherein the volume ratio of Al2O3 powder to SiC powder was 3:1, and the ZrO2 powder and MgO powder accounted for 4.5% and 0.5% of the total volume of the Al2O3 powder and SiC powder, respectively; the ball milling conditions were as follows: the ball mill body was stainless steel, the ball milling medium was ZrO2, the ball-to-material ratio was 10:1, and the ball milling time was 18 hours; to prevent the powder from overheating, the ball milling was stopped every 30 minutes, and the powder was naturally cooled for 30 minutes before continuing; (3) Preparation of composite ceramic materials: (31) The ceramic mixed powder and the bionic Bouligand structure layer are stacked horizontally and alternately in a graphite mold with an inner diameter of 20 mm. The ceramic embryo body finally formed has the following structure: there are 5 layers of ceramic mixed powder and 4 layers of bionic Bouligand structure layer. A bionic Bouligand structure layer is placed between each two adjacent layers of ceramic mixed powder. In each two adjacent layers of bionic Bouligand structure layer, the direction of the fiber bundles in the latter bionic Bouligand structure layer is arranged at 45° counterclockwise relative to the direction of the fiber bundles in the previous bionic Bouligand structure layer. The diameter of the ceramic mixed powder layer formed by the ceramic mixed powder matches the inner diameter of the graphite mold. 1 g of ceramic mixed powder is added each time and is evenly filled into the graphite mold. The structural schematic diagram of the ceramic embryo body in this step is shown in FIG. Figure 1 ; (32) After press-forming at a pressure of 30 MPa using a hydraulic press, the press-forming pressure is maintained and the graphite mold is sent into a plasma vacuum sintering furnace for plasma sintering. In the first step, the temperature is raised to 800°C at 100°C / min and kept at this temperature for 1 hour; in the second step, the temperature is raised to 1600°C at 100°C / min and kept at this temperature for 10 minutes; in the third step, the temperature is cooled to 700°C at 150°C / min and then cooled to room temperature with the furnace. The vacuum is maintained throughout the sintering process.
[0022] Example 2 In step (32), the second step is to raise the temperature to 1650°C at 100°C / min and sinter for 10 minutes. The rest is the same as in Example 3.
[0023] Example 3 In step (32), the second step is to raise the temperature to 1700°C at 100°C / min and sinter for 10 minutes. The rest is the same as in Example 3.
[0024] Example 4 In step (32), the second step is to raise the temperature to 1750°C at 100°C / min and sinter for 10 minutes. The rest is the same as in Example 3.
[0025] Example 5 In step (32), the second step is to raise the temperature to 1700°C at 100°C / min and sinter for 4 minutes. The rest is the same as in Example 3.
[0026] Example 6 In step (32), the second step is to raise the temperature to 1700°C at 100°C / min and sinter for 7 minutes. The rest is the same as in Example 3.
[0027] Example 7 In step (32), the second step is to raise the temperature to 1700°C at 100°C / min and sinter for 13 minutes. The rest is the same as in Example 3.
[0028] Example 8 The particle sizes of the raw materials Al2O3 powder, SiC powder, ZrO2 powder, and MgO powder used in this embodiment are 1 μm, 1 μm, 30 nm, and 1 μm, respectively; A method for preparing a multi-scale bionic structure composite ceramic material comprises the following steps: (1) Preparation of bionic Bouligand structure layer: (11) According to the mass ratio of Al2O3, SiC, ZrO2, and LPCS of 2.3:1.9:0.1:1, Al2O3 powder, SiC powder, and ZrO2 powder were added to LPCS and magnetically stirred for 10 h to obtain LPCS ceramic slurry; (12) After soaking the 12k carbon fiber bundle in acetone for 17 minutes, the bundle was spread on a polytetrafluoroethylene plate in the same direction. Then, the LPCS ceramic slurry was evenly brushed on the surface. After standing at room temperature for 10 hours, the slurry was dried at 150 ° C for 4 hours and cut into original sheets with a diameter of 14 mm to obtain LPCS-C. f / ceramic thin films; (13) Al2O3 powder, SiC powder, and ZrO2 powder with a mass ratio of 2.3:1.9:0.1 were dissolved in anhydrous ethanol, wherein the volume ratio of the total volume of Al2O3 powder, SiC powder, and ZrO2 powder to anhydrous ethanol was 2.8:1, and stirred for 7 hours to obtain a ceramic slurry solution; the cut LPCS-C f / The ceramic film is immersed in the ceramic slurry solution, taken out and dried at 45° C. for 25 minutes to obtain a bionic Bouligand structure layer; (2) Preparation of ceramic mixed powder: Al2O3 powder, SiC powder, ZrO2 powder and MgO powder were mixed, anhydrous ethanol was added thereto, ultrasonically treated and stirred at a speed of 180 rpm for 35 minutes, and then ball milled, vacuum dried at a vacuum degree of 35 Pa and 100°C for 3 hours, and sieved with a 100-mesh sieve after cooling to obtain a ceramic mixed powder; wherein the ZrO2 powder and MgO powder accounted for 4.2% and 0.4% of the total volume of the Al2O3 powder and SiC powder, respectively, and the volume ratio of the Al2O3 powder to the SiC powder was 2.8:1; the ball milling conditions were as follows: the ball mill body was stainless steel, the ball milling medium was ZrO2, the ball-to-material ratio was 10:1, and the ball milling time was 18 hours; to prevent the powder from overheating, the ball milling was stopped every 30 minutes, and the powder was naturally cooled for 30 minutes before continuing; (3) Preparation of composite ceramic materials: (31) The ceramic mixed powder and the bionic Bouligand structure layer are stacked horizontally and alternately in a graphite mold with an inner diameter of 20 mm. The ceramic embryo body finally formed has the following structure: there are 5 layers of ceramic mixed powder and 4 layers of bionic Bouligand structure layer. A bionic Bouligand structure layer is placed between each two adjacent layers of ceramic mixed powder. In each two adjacent layers of bionic Bouligand structure layer, the direction of the fiber bundles in the latter bionic Bouligand structure layer is arranged at 45 degrees counterclockwise relative to the direction of the fiber bundles in the previous bionic Bouligand structure layer. The diameter of the ceramic mixed powder layer formed by the ceramic mixed powder matches the inner diameter of the graphite mold. 1 g of ceramic mixed powder is added each time and is evenly filled into the graphite mold. (32) After press-forming at a pressure of 30 MPa using a hydraulic press, the press-forming pressure is maintained and the graphite mold is sent into a plasma vacuum sintering furnace for plasma sintering. In the first step, the temperature is raised to 800°C at 100°C / min and kept at this temperature for 1 hour; in the second step, the temperature is raised to 1700°C at 100°C / min and kept at this temperature for 10 minutes; in the third step, the temperature is cooled to 700°C at 150°C / min and then cooled to room temperature with the furnace. The vacuum is maintained throughout the sintering process.
[0029] Example 9 The particle sizes of the raw materials Al2O3 powder, SiC powder, ZrO2 powder, and MgO powder used in this embodiment are 0.8 μm, 0.8 μm, 25 nm, and 0.8 μm, respectively; A method for preparing a multi-scale bionic structure composite ceramic material comprises the following steps: (1) Preparation of bionic Bouligand structure layer: (11) According to the mass ratio of Al2O3, SiC, ZrO2, and LPCS of 2.7:2.3:0.3:1, Al2O3 powder, SiC powder, and ZrO2 powder were added to LPCS and magnetically stirred for 15 h to obtain LPCS ceramic slurry; (12) After soaking the 12k carbon fiber bundle in acetone for 20 minutes, the bundle was spread on a polytetrafluoroethylene plate in the same direction. Then, the LPCS ceramic slurry was evenly brushed on the surface. After standing at room temperature for 15 hours, the slurry was dried at 180 ° C for 1 hour and cut into original sheets with a diameter of 16 mm to obtain LPCS-C. f / ceramic thin films; (13) Al2O3 powder, SiC powder, and ZrO2 powder with a mass ratio of 2.7:2.3:0.3 were dissolved in anhydrous ethanol, wherein the volume ratio of the total volume of Al2O3 powder, SiC powder, and ZrO2 powder to anhydrous ethanol was 3.2:1, and stirred for 9 hours to obtain a ceramic slurry solution; the cut LPCS-Cf / The ceramic film is immersed in the ceramic slurry solution, taken out and dried at 40° C. for 30 minutes to obtain a bionic Bouligand structure layer; (2) Preparation of ceramic mixed powder: Al2O3 powder, SiC powder, ZrO2 powder and MgO powder were mixed, anhydrous ethanol was added thereto, ultrasonically treated and stirred at a speed of 180 rpm for 40 minutes, and then ball milled, vacuum dried at a vacuum degree of 35 Pa and 120°C for 4 hours, and sieved with a 100-mesh sieve after cooling to obtain a ceramic mixed powder; wherein the ZrO2 powder and MgO powder accounted for 4.8% and 0.6% of the total volume of the Al2O3 powder and SiC powder, respectively, and the volume ratio of the Al2O3 powder to the SiC powder was 3.2:1; the ball milling conditions were as follows: the ball mill body was stainless steel, the ball milling medium was ZrO2, the ball-to-material ratio was 10:1, and the ball milling time was 18 hours; to prevent the powder from overheating, the ball milling was stopped every 30 minutes, and the powder was naturally cooled for 30 minutes before continuing; (3) Preparation of composite ceramic materials: (31) The ceramic mixed powder and the bionic Bouligand structure layer are stacked horizontally and alternately in a graphite mold with an inner diameter of 20 mm. The ceramic embryo body finally formed has the following structure: there are 5 layers of ceramic mixed powder and 4 layers of bionic Bouligand structure layer. A bionic Bouligand structure layer is placed between each two adjacent layers of ceramic mixed powder. In each two adjacent layers of bionic Bouligand structure layer, the direction of the fiber bundles in the latter bionic Bouligand structure layer is arranged at 45 degrees counterclockwise relative to the direction of the fiber bundles in the previous bionic Bouligand structure layer. The diameter of the ceramic mixed powder layer formed by the ceramic mixed powder matches the inner diameter of the graphite mold. 1 g of ceramic mixed powder is added each time and is evenly filled into the graphite mold. (32) After press-forming at a pressure of 30 MPa using a hydraulic press, the press-forming pressure is maintained and the graphite mold is sent into a plasma vacuum sintering furnace for plasma sintering. In the first step, the temperature is raised to 800°C at 100°C / min and kept at this temperature for 1 hour; in the second step, the temperature is raised to 1700°C at 100°C / min and kept at this temperature for 10 minutes; in the third step, the temperature is water-cooled to 700°C at 150°C / min and then cooled to room temperature with the furnace. The vacuum is maintained throughout the sintering process.
[0030] Comparative Example 1 The ceramic mixed powder and the bionic Bouligand structure layer do not contain ZrO2 powder, and the rest are the same as in Example 3.
[0031] Comparative Example 2 ZrB2 was used instead of ZrO2 powder, and the rest was the same as in Example 3.
[0032] Performance testing 1. Scanning Electron Microscopy The morphology of the composite ceramic materials prepared in Examples 1-4 was analyzed by scanning electron microscopy. Figure 2 ; Among them, the corresponding embodiments 1, 2, 3, and 4 are Figure 2 Middle Figures (a), (b), (c), (d); Depend on Figure 2 It can be seen that the material in (a) presents a uniformly distributed fine-grained structure, the grain boundaries are not tightly bonded, and there are small pores, indicating that the sintering temperature is still low and the sintering is not sufficient; Figure 2 In (b), the grains have grown significantly, the number of pores has decreased, and they are primarily distributed at the triple intersections of the grain boundaries. The grain boundary morphology is clearer, the density is improved, and the sintering process is more complete. In (c), the grains have grown further, and the material has achieved almost complete densification. The three phases show optimal distribution uniformity, and the grain boundaries are clear, regular, and tightly bonded. In (d), the grains have coarsened significantly, and localized phase aggregation has occurred. It can be seen that when sintering in steps, sintering at 1700°C for 10 minutes in the second step can produce ceramic materials with better morphology.
[0033] At the same time, the cross section of the ceramic material in Example 3 was subjected to scanning electron microscopy, and the results showed that Figure 3 . Among them, (a), (b), (c), and (d) correspond to the scanning electron microscope images of the carbon fiber orientations of 0°, 45°, 90°, and 135° in the bionic Bouligand structure layer in the ceramic material, respectively. Among them, the 0° orientation section (a) shows a significant layered distribution feature, the fiber bundles are parallel to the section, and the interlayer interface is clear, indicating that the film and the ceramic matrix form a good interface bond. When the orientation angle increases to 45° (b), the cross-sectional morphology evolves into an obliquely arranged layered structure, which is highly consistent with the designed orientation angle. Significant fiber breakage and rotational orientation characteristics were observed. This structural feature provides an effective mechanical interlocking mechanism for interlayer stress transfer. On the 90° orientation surface (c), a typical honeycomb morphology is presented. This is because the carbon fiber bundles are perpendicular to the fracture surface, making the fiber cross-sectional morphology clearly visible. When the orientation angle is further increased to 135° (d), the cross-section exhibits an obliquely arranged structure, with fiber bundles oriented at 135°. The fracture surface exhibits both granular features and fiber pullout. This composite morphology is beneficial for enhancing the material's anisotropic mechanical properties. Carbon fiber film layers with varying orientation angles create a biomimetic Bouligand structure. This biomimetic Bouligand structure absorbs crack propagation energy through mechanisms such as fiber pullout, fiber fracture, and interfacial behavior, providing anisotropic crack propagation resistance and transforming external loads into multi-directional stresses.
[0034] The crack propagation behavior on the surface and side of the ceramic material of Example 3 was observed. Figure 4 Among them, (a), (d), and (e) are the crack propagation morphologies observed on the side of the ceramic material, (b) is a local enlarged view of (a), (c) is the EDS spectrum analysis of point 1 at the inflection point of crack propagation, and (f) is the crack propagation morphology observed on the surface of the ceramic material; Figure 4 As can be seen from (a), (b), (d) and (e), there are fiber breakage, crack deflection and crack bifurcation on the side of the ceramic material. This is because the nano-ZrO2 particles guide the crack to extend to the Bouligand structure layer through the stress field regulation. The Bouligand structure layer provides anisotropic crack extension resistance and absorbs crack extension energy through mechanisms such as fiber breakage, crack deflection, crack bifurcation and interface behavior. As can be seen from (c), the Zr content in this area is as high as 68.97%. The elemental analysis results show that this area is mainly composed of nano-ZrO2 particles, forming a densely distributed area at the crack extension front, inducing the crack to extend to the Bouligand structure layer. As can be seen from (f), crack bridging and crack deflection exist on the surface of the ceramic material. These behaviors jointly play a toughening mechanism.
[0035] 2. Mechanical properties testing The hardness, fracture toughness and flexural strength of the ceramic materials were tested. The results are shown in Table 1.
[0036] Table 1 Mechanical properties of composite ceramic materials As can be seen from Table 1, the ceramic material provided by the present invention has excellent hardness, fracture toughness and flexural strength. Al2O3 is the matrix material, providing the main structural support. SiC, carbon fiber bundles and LPCS are used to construct the Bouligand structure to enhance the toughening effect of the material. ZrO2 serves as a toughening phase of the composite ceramic material and a micro-control particle of the Bouligand structural layer to optimize the mechanical properties of the material. MgO serves as a sintering aid to promote the densification of the material. When Comparative Example 1 does not contain nano ZrO2 particles, its mechanical properties are significantly reduced, because ZrO2 can not only play the role of nano-particle toughening in the ceramic matrix, but also enhance the interface bonding of the Bouligand structural layer and the overall density of the composite ceramic material, and guide the cracks to extend from the ceramic matrix to the Bouligand structural layer through stress field regulation, further consuming crack propagation energy.
Claims
1. A method for preparing a multi-scale bionic structure composite ceramic material, characterized by: The following steps are involved: (1) Preparation of bionic Bouligand structure layer: (11) Add Al2O3 powder, SiC powder, and ZrO2 powder to LPCS and stir for 10-15 h to obtain LPCS ceramic slurry; (12) After soaking the carbon fiber bundle in acetone for 15-20 minutes, spread it on a polytetrafluoroethylene plate in the same direction, and then evenly apply the LPCS ceramic slurry on its surface. After standing at room temperature for 10-15 hours, dry it and cut it to obtain LPCS-C f / ceramic thin films; (13) Dissolve Al2O3 powder, SiC powder and ZrO2 powder in anhydrous ethanol and stir for 7-9 hours to obtain ceramic slurry solution; f / immersing the ceramic film in the ceramic slurry solution, taking it out and drying it to obtain a bionic Bouligand structure layer; (2) Preparation of ceramic mixed powder: Al2O3 powder, SiC powder, ZrO2 powder and MgO powder are mixed, anhydrous ethanol is added thereto, ultrasonically treated and stirred for 35-50 minutes, ball milled, vacuum dried, cooled and sieved to obtain a ceramic mixed powder; (3) Preparation of composite ceramic materials: (31) Ceramic mixed powder and bionic Bouligand structure layers are stacked alternately horizontally in a graphite mold, and the ceramic embryo body finally formed has the following structure: a bionic Bouligand structure layer is placed between each two adjacent layers of ceramic mixed powder, and the direction of the fiber bundles in the latter bionic Bouligand structure layer is arranged clockwise or counterclockwise relative to the direction of the fiber bundles in the previous bionic Bouligand structure layer in each two adjacent layers of bionic Bouligand structure layer; the diameter of the bionic Bouligand structure layer is 70-80% of the inner diameter of the graphite mold, and the diameter of the ceramic mixed powder layer formed by the ceramic mixed powder matches the inner diameter of the graphite mold; (32) After pressure molding, the pressure of the pressure molding is maintained to perform plasma sintering to obtain a composite ceramic material.
2. The method for preparing a multi-scale bionic structure composite ceramic material according to claim 1, characterized in that: In step (31), there are a total of 5 layers of ceramic mixed powder and 4 layers of bionic Bouligand structure layers; in each of two adjacent bionic Bouligand structure layers, the direction of the fiber bundles in the latter bionic Bouligand structure layer is arranged counterclockwise at 45° relative to the direction of the fiber bundles in the previous bionic Bouligand structure layer.
3. The method for preparing a multi-scale bionic structure composite ceramic material according to claim 2, characterized in that: The inner diameter of the graphite mold is 20 mm, and the weight of each layer of the ceramic mixed powder is 1 g.
4. The method for preparing a multi-scale bionic structure composite ceramic material according to claim 1, characterized in that: The mass ratio of Al2O3 powder, SiC powder, ZrO2 powder and LPCS in step (11) is (2.3-2.7): (1.9-2.3): (0.1-0.3): 1; the ratio of Al2O3 powder, SiC powder and ZrO2 powder in step (13) is the same as that in step (11), and in step (13), the volume ratio of the total volume of Al2O3 powder, SiC powder and ZrO2 powder to anhydrous ethanol is (2.8-3.2): 1; in step (2), ZrO2 powder and MgO powder account for 4.2%-4.8% and 0.4%-0.6% of the total volume of Al2O3 powder and SiC powder, respectively, and the volume ratio of Al2O3 powder to SiC powder is (2.8-3.2):
1.
5. The method for preparing a multi-scale bionic structure composite ceramic material according to claim 1, characterized in that: The plasma sintering adopts step-by-step sintering. The first step is to heat up to 800°C at 100°C / min and keep warm for 1 hour; the second step is to heat up to 1600-1750°C at 100°C / min and keep warm for 4-13 minutes; the third step is to water cool to 700°C at 150°C / min and then cool to room temperature with the furnace. The vacuum is maintained throughout the sintering process.
6. The method for preparing a multi-scale bionic structure composite ceramic material according to claim 5, characterized in that: The second step is to heat up to 1700℃ at 100℃ / min and sinter for 10min.
7. The method for preparing a multi-scale bionic structure composite ceramic material according to claim 1, characterized in that: The particle sizes of the Al2O3 powder, SiC powder, ZrO2 powder and MgO powder are 0.5-1 μm, 0.5-1 μm, 20-30 nm and 0.5-1 μm respectively.
8. The method for preparing a multi-scale bionic structure composite ceramic material according to claim 1, characterized in that: The ball milling conditions are as follows: the ball milling tank is made of stainless steel, the ball milling medium is ZrO2, the ball-to-material ratio is 10:1, and the ball milling time is 12-24 h.
9. The method for preparing a multi-scale bionic structure composite ceramic material according to claim 1, characterized in that: The drying conditions in step (12) are drying at 150-180°C for 1-4 hours; the drying conditions in step (13) are drying at 40-45°C for 25-30 minutes; the vacuum drying conditions in step (2) are vacuum degree <40 Pa, temperature 100-140°C, and drying time 3-4 hours.
10. A multi-scale bionic structure composite ceramic material, characterized by: The product is prepared by the preparation method according to any one of claims 1 to 9.