An aluminum alloy-Al2O3 ceramic composite material and its preparation method

Abstract

The present application belongs to but is not limited to the technical field of composite materials, and particularly relates to an aluminum alloy-Al2O3 ceramic composite material and a preparation method thereof. The aluminum alloy-Al2O3 ceramic composite material is an aluminum alloy matrix wrapped with a continuous gradient minimum surface ceramic skeleton structure. The specific surface area of the skeleton is 0.48 mm ‑1 , and the volume porosity reaches 60%, and the interior is interconnected. The high-speed centrifugal infiltration method designed in the present application uses centrifugal force to accelerate the infiltration of the aluminum alloy liquid matrix. Compared with the traditional preparation method, the process is more rapid, the infiltration can be completed in a short time, the production efficiency is high, and the process structure is simple and reasonable. The ceramic skeleton green body designed in the present application reduces the problems encountered in the traditional ceramic forming process. The porosity is continuously gradient configured, at the same time, the aluminum alloy is filled between the layers of the ceramic skeleton and is also continuously gradient distributed. The three-dimensional constraint provided by the aluminum alloy effectively improves the strength and toughness of the ceramic.

Description

Technical Field

[0001] This invention belongs to, but is not limited to, the field of composite materials technology, and particularly relates to an aluminum alloy-Al2O3 ceramic composite material and its preparation method. Background Technology

[0002] The composite material formed by combining Al2O3 ceramics and aluminum alloys has broad application prospects in industries such as machinery and aerospace. The combination of the two can give full play to the advantages of Al2O3 ceramics, such as high hardness, compressive strength, and high temperature resistance, as well as aluminum alloys, such as good toughness, impact resistance, and good thermal conductivity. However, the traditional bonding method has defects. Due to the large difference in physical and chemical properties between ceramics and aluminum alloys, interfacial stress is easily generated during bonding, resulting in poor stability. When subjected to external forces or temperature changes, fatigue damage such as peeling, cracking, and delamination may occur at the interface. In addition, the traditional process is complicated, involving multiple steps and strict parameter control. Parameters such as temperature, pressure, and time are difficult to control precisely.

[0003] A solid-state reaction method was used to prepare aluminum alloy-Al2O3 ceramic composite materials. This method combines spherical α-Al2O3 powder with an aluminum alloy matrix through a solid-state reaction. However, due to the high reaction temperature and long reaction time of the solid-state reaction, the ceramic components are prone to decomposition, which affects the performance of the final material.

[0004] Patent CN117048146A discloses a multi-component composite aluminum alloy / ceramic protective material, wherein the ceramic is a ceramic block; the ceramic block is embedded inside the aluminum alloy layer, and the panel is composed of the surface of the ceramic block not covered by the aluminum alloy layer and the uppermost aluminum alloy layer; the uppermost aluminum alloy layer is a high-strength aluminum alloy; the back plate is a secondary-strength aluminum alloy; the aluminum alloy layers are arranged alternately from the panel to the back plate in terms of high strength and secondary strength. The back plate thickness accounts for 35-40%; the high-strength aluminum alloy layer in contact with the back plate accounts for 30-35% of the thickness, the sum of the thickness of the remaining high-strength layers is 20-25%, and the sum of the thickness of the secondary-strength layers is 5-10%. However, this material uses a block ceramic structure with a large ceramic content per unit volume, resulting in high hardness but insufficient toughness. Moreover, the uneven dispersion of the ceramic block in this method leads to differences in local properties of the material, affecting the overall strength and toughness performance. In addition, the complexity of this process leads to increased costs, limiting its widespread application.

[0005] In summary, although various methods exist for combining aluminum alloys and Al2O3 ceramics, existing ceramic-metal composite materials still have some shortcomings. Therefore, improvements and optimizations are needed in the design and fabrication processes of ceramic-metal composite materials.

[0006] Based on the above analysis, the following are the urgent technical problems that need to be solved in the existing technology:

[0007] (1) Existing technical methods often fail to effectively improve the interfacial bonding strength between Al2O3 ceramics and aluminum alloys, resulting in a significant reduction in the durability of composite materials under high load conditions.

[0008] (2) Traditional preparation methods make it difficult to achieve uniform distribution of material properties, resulting in significant differences in the physical and mechanical properties of composite materials in different regions, which reduces the reliability of their application.

[0009] (3) Many existing methods have drawbacks such as numerous process steps, long cycle and high cost, which limit their feasibility in large-scale production.

[0010] The closest existing solution can be found in "Bio-Inspired Ceramic–Metal Composites Using Ceramic 3D Printing and Centrifugal Infiltration". Its process also involves first printing a continuous TPMS (tiny surface matte) Al2O3 ceramic framework using photopolymerization, and then centrifugally casting A356 aluminum melt at 1500–3000 rpm to obtain an Al-Al2O3 interpenetrating composite. Related research also shows that if the same TPMS ceramic framework is replaced with a cast aluminum alloy, a similar aluminum-Al2O3 ceramic interpenetrating structure can be obtained, but the volumetric porosity remains uniform along the dimensional direction and lacks gradient functionality. Furthermore, centrifugal casting of traditional Al / SiC or Al / Al2O3 functionally graded composite cylinders has also been reported, showing that while the centrifugal field can rapidly "press" the metal in, it easily leads to radial particle enrichment, microstructure segregation, and uncontrollable interfacial reaction layers.

[0011] However, the above-mentioned solutions generally reveal three major technical bottlenecks: First, although the TPMS lattice is continuous, it lacks a pore size or curvature distribution that varies with spatial coordinates, causing the aluminum melt to stagnate at the nodes and leaving unfilled closed pores, making it difficult to achieve macroscopic zero-defect densification; Second, the ceramic skeleton is often directly subjected to thermal shock from the aluminum melt at room temperature, which will form microcracks and a brittle Al2O3 / Al interface layer at the interface, reducing the overall impact toughness; Third, the centrifugal force is driven solely by density difference, which cannot finely control the pore-metal distribution gradient, resulting in unpredictable radial functional gradient and high performance dispersion. Summary of the Invention

[0012] To address the problems existing in the prior art, this invention provides a method for preparing aluminum alloy-Al2O3 ceramic composite materials. The aim is to solve the technical problems and shortcomings of existing aluminum alloy-Al2O3 ceramic composite materials in terms of bonding strength, material performance consistency, and production process by using a centrifugal liquid metal infiltration method and a ceramic skeleton based on a continuous gradient minimal surface.

[0013] The implementation method of the present invention is as follows: an aluminum alloy-Al2O3 ceramic composite material, which presents a structure in which an aluminum alloy matrix is ​​wrapped around a ceramic skeleton; a centrifugal liquid metal infiltration method is used to promote the uniform infiltration of liquid aluminum alloy in a ceramic skeleton with a continuous gradient of minimal curvature.

[0014] In aluminum alloy-Al2O3 ceramic composites, the specific surface area (surface area / volume) of the continuously gradient minimal curved surface ceramic skeleton is 0.48 mm². -1 It has a volumetric porosity of 60% and is internally interconnected.

[0015] Furthermore, the porosity of the continuous gradient minimum surface in the composite material varies functionally, as shown by the formula:

[0016]

[0017]

[0018] In this function All are length values ​​in each direction of the generated continuous gradient minimum surface structure; To be the size of the unit cell of the continuously gradient minimum surface, in this invention Take 1.5mm; , This parameter is an arbitrary constant; modifying it can yield continuous gradient minimum surface models with different continuous gradient variations.

[0019] Furthermore, the high-speed centrifugation method involves placing the sintered Al2O3 ceramic skeleton blank into a casting mold, which is then placed on the support of a high-frequency centrifugal casting machine. The casting mold is sealed on all sides, and the liquid aluminum alloy matrix is ​​placed in a casting crucible. During centrifugation, the remaining liquid aluminum alloy matrix is ​​melted and cast under the constraint of the mold to form the surface and surrounding walls of the composite material.

[0020] Furthermore, the material of the continuous gradient minimal surface ceramic skeleton is oxide ceramic; the material of the centrifugal matrix alloy is aluminum alloy.

[0021] Another objective of this invention is to provide a method for preparing the aluminum alloy-Al2O3 ceramic composite material, comprising the following steps: design of a continuous gradient minimal surface ceramic skeleton structure, 3D printing of the ceramic skeleton, obtaining a ceramic blank, aluminum alloy melting, centrifugal infiltration, cooling and solidification, and post-processing. The specific steps are as follows:

[0022] Step 1: Design a continuous gradient minimum surface Al2O3 ceramic framework structure: Use nTopology to design the corresponding 3D model for the continuous gradient minimum surface ceramic framework, and the designed structure meets the structural strength requirements.

[0023] Step 2: Complete the 3D printing of the ceramic skeleton: Prepare Al2O3 ceramic slurry and use a photopolymerization 3D printer to print the ceramic green body.

[0024] Step 3: Obtain the ceramic skeleton blank: Remove excess slurry from the surface of the obtained ceramic skeleton blank and then dry, degrease and sinter.

[0025] Step 4, aluminum alloy smelting: The aluminum alloy raw materials are smelted to obtain a liquid aluminum alloy matrix.

[0026] Step 5, centrifugal melting and infiltration: Place the ceramic skeleton blank on the mold fixing device of the high-frequency centrifugal casting machine, and then start the high-frequency centrifugal casting machine to allow the liquid aluminum alloy to be injected into the ceramic skeleton blank through the casting hole under the action of centrifugal force.

[0027] Step 6, Cooling and solidification: After the liquid aluminum alloy has been completely injected into the ceramic skeleton blank through the casting hole, stop the high-frequency centrifugal casting machine and cool and solidify the composite material.

[0028] Step 7, Post-processing: After molding and demolding, the material is cooled and polished at room temperature to obtain the aluminum alloy-Al2O3 ceramic composite material based on centrifugal liquid metal infiltration method.

[0029] Furthermore, the design of the continuous gradient minimum surface ceramic skeleton structure in step one includes the following: statistical analysis of the structural characteristics of the continuous gradient minimum surface ceramic skeleton, comprehensive summary and generalization of its structural features, followed by modeling operations.

[0030] Furthermore, the degreasing process in step three is as follows: the temperature is gradually increased to 800℃ at a heating rate of 4℃ / min, held for 1 hour, then increased to 1400℃ at a heating rate of 10℃ / min, and then the heating rate is reduced to 5℃ / min until it reaches 1625℃. After holding for 1 hour, it is cooled with the furnace to complete the degreasing and sintering of the Al2O3 ceramic green body.

[0031] Furthermore, the centrifugal melting process in step five is as follows: the Al2O3 ceramic skeleton blank is placed in the melting and casting mold, which is placed on the bracket of the high-frequency centrifugal casting machine. The melting and casting mold is closed on all sides (except for the part in contact with the casting crucible, which has a pore for the liquid aluminum alloy matrix to pass through). Then, the liquid aluminum alloy is injected into the casting crucible of the high-frequency centrifugal casting machine. The high-frequency centrifugal casting machine is started, and the centrifugal speed is 1500-2800 rpm, so that the liquid aluminum alloy is injected into the ceramic skeleton blank through the casting hole under the action of centrifugal force.

[0032] Furthermore, the post-processing in step seven is as follows: the aluminum alloy-ceramic composite material prepared by centrifugal melt infiltration is solution treated at 500℃ for 2 hours, followed by quenching and rapid cooling. Next, the material is subjected to low-temperature heat treatment at 200℃ for 12 hours; after removal, the excess aluminum alloy around the composite material is ground and shaped using a grinding tool to obtain the aluminum alloy-Al2O3 ceramic composite material based on centrifugal liquid metal infiltration method.

[0033] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0034] This invention optimizes the above three points one by one through parametric design of "continuous gradient minimal curved surface", isothermal preheating of the skeleton at 660 ℃ and synchronous mold cavity filling and covering strategy, thereby achieving full-volume melting and infiltration, metallurgical-grade interface bonding and designable three-dimensional gradient density, thus breaking through the limitations of existing technologies. The aluminum alloy-Al2O3 ceramic composite material and its preparation method provided by this invention through centrifugal liquid metal melting and infiltration method specifically involve a ceramic skeleton with a special structure of continuous gradient minimal curved surface, and the preparation of an aluminum alloy-Al2O3 ceramic composite material with high strength and performance by combining it with the centrifugal method.

[0035] The high-speed centrifugal melting and infiltration method designed in this invention utilizes centrifugal force to accelerate the infiltration of liquid aluminum alloy into the matrix. This process is much faster than traditional preparation methods, completing melting and infiltration in a short time and achieving high production efficiency. Traditional methods for preparing aluminum alloy-Al2O3 ceramic composites generally employ metal infiltration, relying on static pressure capillary action to infiltrate the ceramic preform. This process requires waiting for the metal to melt and flow, infiltrating the porous ceramic pores, resulting in a long preparation cycle and low efficiency. The dynamic pressure generated by centrifugal force is significantly higher than that of traditional static pressure, forcing liquid aluminum to fill the micropores and reducing the preparation cycle.

[0036] The composite material prepared by the method of the present invention has a denser and more uniform microstructure. Traditional metal infiltration methods result in uneven penetration of small-pore porous ceramic structures, which can easily lead to unfilled areas. However, the centrifugal force direction of the method of the present invention is controllable, and the liquid metal penetrates uniformly along the radial direction of the porous ceramic preform, thereby improving the overall density of the composite material.

[0037] The composite material prepared by the method of this invention has better interfacial bonding strength. High-speed centrifugation significantly shortens the high-temperature contact time between the metal and Al2O3 ceramic, avoiding the formation of brittle substances that reduce the mechanical properties of the material due to interfacial reaction caused by prolonged high-temperature contact. The overall mechanical properties of the composite material are improved.

[0038] The Al2O3 ceramic and aluminum alloy bonding process designed in this invention has fewer steps and a simpler process flow compared to traditional methods. The Al2O3 ceramic framework blank designed in this invention features a continuous gradient porosity configuration, avoiding stress concentration problems associated with uniform pore structures and improving structural strength. Simultaneously, the aluminum alloy, distributed in a continuous gradient between the layers of the ceramic framework, creates a three-dimensional constraint between the aluminum alloy and the ceramic framework. This gradient composite material effectively reduces the significant acoustic impedance between the two different materials, minimizes stress wave reflection at the interface, and improves stress wave transmission efficiency.

[0039] The expected benefits and commercial value of the technical solution after its transformation are as follows: After the transformation of this technical solution, it can generate huge potential economic benefits. In the machinery manufacturing industry, it is an ideal material for cutting tools and wear-resistant parts. In the defense and military industry, it can be used to manufacture protective armor for weapons and equipment. It is widely used in many industries, providing key support and innovative impetus for the development of various fields, and is expected to drive technological innovation and progress in related industries. Attached Figure Description

[0040] Figure 1 This is a process flow diagram of preparing aluminum alloy-Al2O3 ceramic composite material by centrifugal infiltration provided in the embodiments of the present invention;

[0041] Figure 2 This is a schematic diagram of a porous ceramic preform infiltrated by centrifugal aluminum liquid according to an embodiment of the present invention;

[0042] Figure 3 This is a temperature curve diagram of the degreasing process provided in the embodiments of the present invention;

[0043] Figure 4 This is a schematic diagram of a high-frequency centrifugal casting machine provided in an embodiment of the present invention;

[0044] Figure 5 This is a structural diagram of the high-frequency centrifugal casting machine provided in an embodiment of the present invention;

[0045] Figure 6 This is a perspective view of the high-frequency centrifugal casting machine provided in an embodiment of the present invention;

[0046] Figure 7 This is a top view of the high-frequency centrifugal casting machine provided in an embodiment of the present invention;

[0047] Figure 8This is a side view of a high-frequency centrifugal casting machine provided in an embodiment of the present invention;

[0048] Figure 9 This is a schematic diagram of finished products with different aluminum alloy contents provided in the embodiments of the present invention. Detailed Implementation

[0049] 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.

[0050] Traditional metal matrix composites often suffer from poor wettability of the molten metal to the ceramic phase, significant thermal expansion mismatch, and uncontrollable pore distribution, leading to insufficient permeation, easy interface cracking, and difficulty in achieving a synergistic effect of high density and high strength at the macroscopic structural scale. This invention first uses a continuous gradient three-periodic minimal surface (TPMS) as the core framework morphology. Through topology-optimization modeling, the nodal curvature and wall thickness evolve continuously in three-dimensional space. By designing the gradient curvature, the isolated closed pores and stress concentration phenomena common in traditional foam ceramics are reduced, enabling the aluminum melt to achieve full-volume permeation without capillary blockage under subsequent controlled kinetic conditions.

[0051] Based on photopolymerization Al2O3 ceramic stereolithography, Al2O3 ceramic slurry is cured layer by layer under a microscale light field. The porosity continuously varies along the cos × sin coupling function, ensuring an increase in macroscopic specific surface area while suppressing abrupt shear changes in liquid metal flow through gradient pore size. Subsequent multi-stage heating debinding-sintering curves construct a high-density inorganic network in a vacuum environment, simultaneously eliminating organic residues and forming interconnected open channels. This provides excellent capillary adsorption driving force and thermal stability support for the melting and infiltration stage.

[0052] The Al2O3 ceramic preform was slowly heated to 660 °C and held isothermally to achieve quasi-thermal equilibrium between its thermal field and the Al-Si-Mg matrix to be injected. This "isothermal butt welding" strategy effectively reduced transient thermal shock, thereby preventing the propagation of ceramic microcracks. Simultaneously, the large curvature transition surface with minimal gradient acted as a stress diffuser, gradually attenuating local tensile stress peaks during subsequent metal solidification and shrinkage, significantly improving interface integrity.

[0053] In the high-speed centrifugal casting stage, a radial acceleration of 1500–2800 rpm provides a stable dynamic pressure gradient for the aluminum melt within the range of tens to hundreds of times gravity, overcoming the problems of low penetration rate and easy residue formation in macropores caused by traditional vacuum negative pressure. The unidirectional flow field on the confined cavity of the rotating body can also simultaneously expel hydrogen and non-metallic inclusions carried by the melt, achieving metallurgical-grade bonding without pores or oxide film interlayers. The remaining melt is constrained in the mold gap to form a self-coating layer, completing the one-time integral molding.

[0054] Al-Si-O-Mg (at the interface) or The thickness of the reaction layer is controlled by the surface energy of the gradient pore wall and the transient mass transfer rate driven by centrifugation, generating a continuous and dense self-generated Al2O3 ceramic-metal transition zone, which transforms the interface from a simple mechanical interlocking to a chemical-metallurgical dual coupling bonding mode; its interlayer micro-strain is eliminated by the hyperbolic curvature averaging of the TPMS framework, thus the macroscopic part exhibits specific strength and specific modulus that exceed the linear superposition prediction.

[0055] By leveraging programmable minimal surface topology design, photopolymerization of Al2O3 ceramics additive manufacturing, and high-speed centrifugal liquid metal infiltration molding process, this invention overcomes the triple bottlenecks of controllable pore size, skeleton continuity, and interface metallurgical bonding that are difficult to achieve simultaneously in traditional manufacturing methods. It realizes the preparation of aluminum alloy-Al2O3 ceramic composite materials under the "digital design-additive manufacturing-integrated casting" path, providing a new, efficient, and scalable paradigm for lightweight aerospace structures and high-heat-load heat dissipation components.

[0056] The aluminum alloy-Al2O3 ceramic composite material provided by this invention has a structure of aluminum alloy encapsulating a continuous gradient minimal curved surface ceramic framework; the preparation process route is as follows: Figure 1 As shown, a continuous gradient ceramic skeleton was prepared by modeling and design and 3D printing. Then, the matrix aluminum alloy liquid was injected into the pre-made continuous gradient ceramic skeleton through the casting hole by centrifugation, so as to realize the integral casting of aluminum alloy-Al2O3 ceramic composite material.

[0057] Furthermore, the porosity of the continuous gradient minimum surface in the composite material varies as a function, and the formula for the function is as follows:

[0058]

[0059]

[0060] In this function All are length values ​​in each direction of the generated continuous gradient minimum surface structure; To be the size of the unit cell of the continuously gradient minimum surface, in this invention Take 1.5mm; a and b are arbitrary constants. Modifying these parameters can yield continuous gradient minimum surface models with different continuous gradient changes.

[0061] Furthermore, the high-speed centrifugation method involves placing the sintered ceramic skeleton blank into a casting mold, which is then placed on the support of a high-frequency centrifugal casting machine. The casting mold is sealed on all sides (except for the part in contact with the casting crucible, which has a pore for the matrix aluminum alloy liquid to pass through). The matrix aluminum alloy liquid is placed in the casting crucible. During centrifugation, the remaining matrix aluminum alloy liquid is melted and cast under the constraint of the mold to form the surface and surrounding walls of the composite material.

[0062] Furthermore, the material of the continuous gradient minimal surface ceramic skeleton is oxide ceramic; the material of the centrifugal matrix alloy is aluminum alloy.

[0063] Another object of the present invention is to provide a method for preparing the aluminum alloy-Al2O3 ceramic composite material, wherein the method for preparing the aluminum alloy-Al2O3 ceramic composite material includes the following steps:

[0064] Step 1: Design a continuous gradient minimum surface ceramic skeleton structure: Use nTopology to design the corresponding 3D model for the continuous gradient minimum surface ceramic skeleton, and the designed structure meets the structural strength requirements.

[0065] Step 2: Complete the 3D printing of the ceramic skeleton: Prepare the ceramic slurry and use a photopolymerization 3D printer to print the slurry into shape.

[0066] Step 3, obtaining the ceramic skeleton blank: remove impurities from the surface of the obtained ceramic skeleton blank and then dry, degrease and sinter.

[0067] Step 4, aluminum alloy smelting: The aluminum alloy raw materials are smelted to obtain a liquid aluminum alloy matrix.

[0068] Step 5, Centrifugal Melting: Place the ceramic skeleton blank into the melting and casting mold, which is placed on the bracket of the high-frequency centrifugal casting machine. The melting and casting mold is sealed on all sides (except for the part that connects with the casting crucible, which has a gap for the base aluminum alloy liquid to pass through). Then, inject the base aluminum alloy liquid into the casting crucible of the high-frequency centrifugal casting machine, start the high-frequency centrifugal casting machine, and set the centrifugal speed to 1500-2800 rpm. Under the action of centrifugal force, the base aluminum alloy liquid is injected into the ceramic skeleton blank through the casting hole.

[0069] Step 6, Cooling and solidification: After the liquid aluminum alloy matrix has been completely injected into the ceramic skeleton blank through the casting hole, stop the high-frequency centrifugal casting machine and cool and solidify the composite material.

[0070] Step 7, Post-processing: After molding and demolding, the material is cooled and polished at room temperature to obtain the aluminum alloy-Al2O3 ceramic composite material based on centrifugal liquid metal infiltration method.

[0071] Furthermore, the design of the continuous gradient minimum surface ceramic skeleton structure in step one includes:

[0072] The structural characteristics of the ceramic skeleton were thoroughly summarized, and a corresponding 3D model was designed. The assembly demonstration of the continuous gradient minimal surface skeleton was generated in Rhino.

[0073] Furthermore, in step two, the sample is placed in a vacuum sintering furnace for debinding and sintering. The debinding process is as follows: the temperature is raised to 800°C at a heating rate of 4°C / min, held for 1 hour, then raised to 1400°C at a heating rate of 10°C / min, and then the heating rate is reduced to 5°C / min until it reaches 1625°C. After holding for 1 hour, it is cooled with the furnace to complete the debinding and sintering of the ceramic material.

[0074] Furthermore, in step three, the sintered ceramic blank is heated to 660°C and held at that temperature. This helps to better bond with the liquid aluminum alloy matrix at a temperature higher than 660°C, thereby improving the interfacial bonding strength between the ceramic and the aluminum alloy.

[0075] Furthermore, in step four, the aluminum alloy block is placed in an induction furnace, where electromagnetic induction causes the base aluminum alloy to generate eddy currents and melt. The molten base aluminum alloy is then poured into the casting crucible of a high-frequency centrifugal casting machine.

[0076] Furthermore, in step five, after spraying a release agent onto the four walls of the casting mold, the ceramic skeleton blank is placed inside. After centrifugation for a period of time, the casting mold is removed, and the color of the aluminum alloy in the pores (i.e., the outer layer in contact with air) is observed. Based on its surface characteristics, the success of centrifugal melting and infiltration is determined. Experimental calculations show that finished products with an aluminum alloy filling content of 30-40% have better mechanical properties, while those with filling contents of 10-30% and 40-90% have poorer properties.

[0077] Furthermore, in step six, the aluminum alloy-Al2O3 ceramic composite material is naturally cooled.

[0078] Furthermore, in step seven, the aluminum alloy-ceramic composite material prepared by centrifugal melt infiltration is solution treated at 500°C for 2 hours, followed by quenching and rapid cooling. Next, the material is subjected to low-temperature heat treatment at 200°C for 12 hours; after removal, the excess aluminum alloy around the composite material is ground and shaped using a grinding tool to obtain the aluminum alloy-Al2O3 ceramic composite material based on centrifugal liquid metal infiltration method.

[0079] In the aluminum alloy-Al2O3 ceramic composite material of this invention, the specific surface area (surface area / volume) of the continuously gradient minimal curved surface ceramic skeleton is: It has a volumetric porosity of 60% and is internally interconnected.

[0080] Please see Figure 1 The aluminum alloy-Al2O3 ceramic composite material and its preparation method include the design of a continuous gradient minimal curved surface ceramic skeleton structure, 3D printing of the ceramic skeleton, obtaining the ceramic green body, aluminum alloy melting, centrifugal melting and infiltration, cooling and solidification, and post-processing steps. The specific steps are as follows:

[0081] (1): Design a three-dimensional model of a ceramic skeleton with a continuous gradient minimum surface that satisfies the structural strength using nTopology.

[0082] (2): Prepare Al2O3 ceramic slurry, and print it using a photopolymerization 3D printer to obtain a ceramic blank.

[0083] (3): Remove excess slurry from the surface of ceramic green body by removing Al2O3, then dry, degrease and sinter.

[0084] (4): The aluminum alloy material is placed in the crucible of a high-frequency centrifugal casting machine and melted to obtain liquid aluminum alloy.

[0085] (5): Place the ceramic matrix on the mold fixing device of the high-frequency centrifugal casting machine, start the machine, and inject the liquid aluminum alloy into the ceramic matrix under the action of centrifugal force.

[0086] (6): After the liquid aluminum alloy is fully injected, stop the machine and cool and solidify the composite material.

[0087] (7): After molding, the aluminum alloy-ceramic composite material is obtained by demolding, post-processing, cooling at room temperature and grinding.

[0088] In step (2) of this embodiment, the sample is placed in a vacuum sintering furnace for debinding and sintering. The debinding process is as follows: the temperature is raised to 175°C at a heating rate of 0.4°C / min, held for 90 min, then raised to 410°C at a heating rate of 0.2°C / min, and held for 120 min. Then the heating rate is changed to 0.3°C / min, and the temperature is raised to 600°C and held for 120 min. Subsequently, the temperature is raised to 800°C at a heating rate of 5°C / min under an argon atmosphere and held for 120 min. Then the temperature is raised to 1000°C at a heating rate of 5°C / min and held for 180 min. After that, the temperature is cooled with the furnace to complete the debinding and sintering of the ceramic material.

[0089] In step (3) of this embodiment, after the ceramic blank is successfully sintered, it is further heated to 660°C and then held at that temperature. This allows for a more ideal bonding condition at the interface when the ceramic comes into contact with the aluminum alloy, which is in a high-temperature liquid state above 660°C. This results in a tighter and stronger bond between the ceramic and the aluminum alloy, effectively strengthening their interfacial bonding strength and providing a solid process guarantee for the preparation of high-performance aluminum alloy-Al2O3 ceramic composite materials.

[0090] In step (4) of this embodiment of the invention, an aluminum alloy block is placed inside an induction furnace. Using the principle of electromagnetic induction, eddy currents are generated inside the aluminum alloy block, causing it to heat up due to the eddy current effect until it reaches its melting point and melts into a liquid state. Subsequently, the molten aluminum alloy is transferred to a casting crucible provided by a high-frequency centrifugal casting machine to ensure that the aluminum alloy can be precisely processed according to predetermined process requirements.

[0091] In step (5) of this embodiment, a release agent is sprayed on the four walls of the casting mold. After centrifugation for a period of time, the casting mold is removed. By observing the color of the aluminum alloy in the pores, i.e., the outer layer in contact with air, the surface characteristics are used to determine whether centrifugal melting is successful. If centrifugal melting is successful, the outer aluminum alloy surface of the mold is smooth and uniform, with normal color, and the pores are fine, uniform, and without obvious defects, indicating that the aluminum alloy has fully melted into the pores of the ceramic body, resulting in a good composite structure. If centrifugal melting fails, the aluminum alloy surface is rough, the color is abnormally dark or has black spots, which may be due to poor temperature control leading to oxidation or uneven composition; the pores are concentrated and not filled, which may be due to insufficient centrifugal force, short melting time, or unfavorable pore structure of the ceramic body; the appearance of delamination may be due to poor wettability or problems with pretreatment. All of these indicate that the melting has not met expectations, and the quality of the composite material is difficult to guarantee.

[0092] In step (7) of this embodiment, the aluminum alloy-ceramic composite material prepared by centrifugal melting is solution treated at 500°C for 2 hours, followed by quenching and rapid cooling. Next, the material is subjected to low-temperature heat treatment at 200°C for 12 hours; after removal, the excess aluminum alloy around the composite material is ground and shaped using a grinding tool to obtain the aluminum alloy-Al2O3 ceramic composite material based on centrifugal liquid metal melting method.

[0093] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0094] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An aluminum alloy-Al2O3 ceramic composite material, characterized in that, It presents a structure in which an aluminum alloy matrix encapsulates a ceramic skeleton; a centrifugal liquid metal infiltration method is used to promote uniform infiltration of liquid aluminum alloy in a ceramic skeleton with a continuous gradient of minimal curvature. In aluminum alloy-Al2O3 ceramic composites, the specific surface area of ​​the continuously gradient minimal curved surface ceramic skeleton is 0.48 mm². -1 It has a volumetric porosity of 60% and is internally interconnected.

2. The aluminum alloy-Al2O3 ceramic composite material as described in claim 1, characterized in that, The porosity of the continuous gradient minimum surface in the composite material varies as a function, and the function formula is: ； In this function All are length values ​​in each direction of the generated continuous gradient minimum surface structure; To be the size of the unit cell of the continuously gradient minimum surface, in this invention Take 1.5mm; a and b are arbitrary constants. Modifying these parameters can yield continuous gradient minimum surface models with different continuous gradient changes.

3. The aluminum alloy-Al2O3 ceramic composite material as described in claim 1, characterized in that, The high-speed centrifugation method involves placing the sintered ceramic skeleton blank into a casting mold, which is then placed on the support of a high-frequency centrifugal casting machine. The casting mold is sealed on all sides, and the liquid aluminum alloy matrix is ​​placed in a casting crucible. During centrifugation, the remaining liquid aluminum alloy matrix is ​​melted and cast under the constraint of the mold to form the surface and surrounding walls of the composite material.

4. The aluminum alloy-Al2O3 ceramic composite material as described in claim 1, characterized in that, The continuous gradient minimal surface ceramic skeleton is made of oxide ceramic; the centrifugal matrix alloy is made of aluminum alloy.

5. A method for preparing aluminum alloy-Al2O3 ceramic composite materials, characterized in that, The process includes the design of a continuous gradient minimal surface ceramic skeleton structure, 3D printing of the ceramic skeleton, obtaining the ceramic blank, aluminum alloy melting, centrifugal infiltration, cooling and solidification, and post-processing steps; the specific steps are as follows: Step 1: Design a continuous gradient minimum surface ceramic skeleton structure: Use nTopology to design the corresponding 3D model for the continuous gradient minimum surface ceramic skeleton, and the designed structure meets the structural strength requirements. Step 2, complete the 3D printing of the ceramic skeleton: prepare the ceramic slurry and use a photopolymerization 3D printer to print the slurry into shape; Step 3, obtaining the ceramic skeleton green body: remove excess slurry from the surface of the obtained ceramic skeleton green body and dry, degrease and sinter; Step 4, aluminum alloy smelting: The aluminum alloy raw material is smelted to obtain a liquid aluminum alloy matrix; Step 5, centrifugal melting and infiltration: Place the ceramic skeleton blank on the mold fixing device of the high-frequency centrifugal casting machine, and then start the high-frequency centrifugal casting machine to allow the liquid aluminum alloy to be injected into the ceramic skeleton blank through the casting hole under the action of centrifugal force; Step 6, Cooling and solidification: After the liquid aluminum alloy has been completely injected into the ceramic skeleton blank through the casting hole, stop the high-frequency centrifugal casting machine and cool and solidify the composite material. Step 7, Post-processing: After molding and demolding, the material is cooled and polished at room temperature to obtain the aluminum alloy-Al2O3 ceramic composite material based on centrifugal liquid metal infiltration method.

6. The method for preparing aluminum alloy-Al2O3 ceramic composite material as described in claim 5, characterized in that, The design of the continuous gradient minimum surface ceramic skeleton structure in step one includes the following: statistical analysis of the structural characteristics of the continuous gradient minimum surface ceramic skeleton, comprehensive summary and generalization of its structural features, and then modeling operation.

7. The method for preparing aluminum alloy-Al2O3 ceramic composite material as described in claim 5, characterized in that, The degreasing process in step three is as follows: the temperature is gradually increased to 800℃ at a heating rate of 4℃ / min, held for 1 hour, then increased to 1400℃ at a heating rate of 10℃ / min, and then the heating rate is reduced to 5℃ / min until it reaches 1625℃. After holding for 1 hour, it is cooled with the furnace to complete the degreasing and sintering of the ceramic material.

8. The method for preparing aluminum alloy-Al2O3 ceramic composite material as described in claim 5, characterized in that, The centrifugal melting process in step five is as follows: the ceramic skeleton blank is placed in the melting and casting mold, the melting and casting mold is placed on the bracket of the high-frequency centrifugal casting machine, the melting and casting mold is sealed on all sides, and then the liquid aluminum alloy is injected into the casting crucible of the high-frequency centrifugal casting machine. The high-frequency centrifugal casting machine is started, and the centrifugal speed is 1500-2800 rpm, so that the liquid aluminum alloy is injected into the ceramic skeleton blank through the casting hole under the action of centrifugal force.

9. The method for preparing aluminum alloy-Al2O3 ceramic composite material as described in claim 5, characterized in that, The post-processing in step seven is as follows: the aluminum alloy-ceramic composite material prepared by centrifugal melting infiltration is solution treated at 500℃ for 2 hours, followed by quenching and rapid cooling; then the material is subjected to low-temperature heat treatment at 200℃ for 12 hours; after removal, the excess aluminum alloy around the composite material is ground and shaped using a grinding tool to obtain the aluminum alloy-Al2O3 ceramic composite material based on centrifugal liquid metal melting infiltration method.

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