An aluminum-based silicon carbide composite material, its preparation method and application

Abstract

This invention belongs to the technical field of metal-ceramic additive manufacturing. It discloses an aluminum-based silicon carbide composite material and its preparation method and application. The method includes the following steps: (1) using composite powder made by mixing silicon carbide with different particle size distributions and a binder as raw material, and printing it with a laser sintering device to obtain a silicon carbide preform; (2) immersing the silicon carbide preform in a silica sol with a concentration of 10% to 30% for 2 to 4 hours, and degreasing the immersed silicon carbide preform to obtain a silicon carbide preform; (3) pre-oxidizing the silicon carbide preform to obtain a silicon carbide porous skeleton, and vacuum pressure impregnating the silicon carbide porous skeleton with aluminum alloy to obtain an aluminum-based silicon carbide composite material. This invention has the characteristics of preparing high performance, rapid prototyping of complex structures, and stable interface between silicon carbide and aluminum alloy.

Description

Technical Field

[0001] This invention belongs to the technical field of metal-ceramic additive manufacturing, and more specifically, relates to an aluminum-based silicon carbide composite material, its preparation method, and its application. Background Technology

[0002] SiC / Al composites, due to their high thermal conductivity, excellent mechanical properties, and low coefficient of thermal expansion, have become important materials in aerospace, electronic packaging, and thermal management. With the development of more complex, high-performance components in critical equipment, higher demands are being placed on the preparation and processing technologies of SiC / Al composites. Typically, methods for preparing SiC / Al composites include powder metallurgy, casting, and infiltration. However, these traditional methods face challenges when manufacturing SiC / Al composite components with complex structures, such as low density, internal defects, and difficulty in precisely controlling local composition and structure. Furthermore, SiC / Al composites formed using traditional methods also present significant difficulties in subsequent processing. As described in "ZL201110256283.2 Processing Method for Aluminum-Based Silicon Carbide Structural Components for Aerospace Gyroscopes," current processing methods for aluminum-based silicon carbide structural components require high-precision cutting tools, are difficult to execute, and are costly. Therefore, it is difficult to meet the demand for rapid manufacturing of personalized, refined, lightweight, and complex SiC / Al composite components, which significantly limits the development and application of SiC / Al composites.

[0003] Currently, additive manufacturing techniques for preparing aluminum-based silicon carbide (SiC / Al) mainly fall into two categories: direct printing (laser bed fusion, SLM) and indirect printing combined with post-processing (laser bed sintering, SLS). The former involves directly sintering and melting aluminum powder and silicon carbide particles, while the latter involves adding organic or inorganic binders to form a preform of silicon carbide. After debinding, molten aluminum is impregnated into the preform under pressure or without pressure to obtain the final SiC / Al composite material. For directly printed SiC / Al composites, the volume fraction of silicon carbide cannot be too high (below 20%). Excessive silicon carbide content can lead to excessive side reactions during printing, resulting in numerous defects or even failure to form the final product. In contrast, indirectly printed SiC / Al composites can achieve a volume fraction controllable between 30% and 70%, producing finished products with fewer defects, higher precision, and stronger consistency.

[0004] Compared with direct printing, the indirect printing combined with post-processing molding method first needs to solve two very critical problems: (1) Using inorganic binders will introduce more other phases, which will lead to a decrease in silicon carbide content. Therefore, organic binders are used as binders for silicon carbide preform molding. The use of organic binders will remain in the preform as residual carbon after degreasing. Although the residual carbon can be removed by pre-oxidation, the mechanical strength of the preform will drop sharply or even pulverize while the residual carbon is eliminated by pre-oxidation. (2) The presence of residual carbon will directly react with the aluminum liquid to generate the brittle phase Al4C3. The presence of this phase will lead to a sharp decline in the performance of the composite material. On the other hand, the free residual carbon and the generated Al4C3 phase will cause severe lamellar delamination (e.g. Figure 2 (as shown in a). Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides an aluminum-based silicon carbide composite material, its preparation method and application. The preparation method not only gives full play to the advantages of selective laser sintering in the preparation of aluminum-based silicon carbide composite materials, but also solves the problem of residual carbon after degreasing of organic binders. It improves the mechanical properties of the preform while improving the interface between aluminum alloy and silicon carbide particles, and finally obtains a SiC / Al composite material with stable performance.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for preparing an aluminum-based silicon carbide composite material is provided, the method comprising the following steps:

[0007] (1) A composite powder made by mixing silicon carbide with a binder with different particle size distribution is used as raw material and printed by laser sintering equipment to obtain silicon carbide blank;

[0008] (2) Immerse the silicon carbide blank in a silica sol with a concentration of 10% to 30% for 2 to 4 hours, and degrease the immersed silicon carbide blank to obtain a silicon carbide preform.

[0009] (3) The silicon carbide preform is subjected to pre-oxidation treatment to obtain a silicon carbide porous skeleton, and the silicon carbide porous skeleton is subjected to vacuum pressure impregnation of aluminum alloy to obtain an aluminum-based silicon carbide composite material.

[0010] Further, in step (1), firstly, silicon carbide particles of different sizes are mixed with binder by mechanical mixing; then, a digital model of the structure to be prepared is established using three-dimensional drawing software, and the digital model is converted into an STL file, and then the STL file is imported into the selective laser sintering equipment; finally, the mixture is added to the selective laser sintering equipment for printing to obtain a silicon carbide blank.

[0011] Furthermore, the silicon carbide particles include coarse silicon carbide particles and fine silicon carbide particles, with a particle size ratio of coarse silicon carbide particles to fine silicon carbide particles of 3:1 to 9:1. The mass percentage of coarse silicon carbide powder is 40% to 90%, the mass percentage of fine silicon carbide powder is 40% to 90%, and the mass content of binder is 5% to 20%.

[0012] Furthermore, the pre-laid powder bed temperature is 25℃~45℃, and the printing parameters for selective laser sintering are: laser power of 6W~12W, filling speed of 1500mm / s~2500mm / s, and filling thickness of 0.1mm~0.2mm.

[0013] Furthermore, during the degreasing process, the holding temperature is 600℃~800℃, and the holding time is 1.5h~3h.

[0014] Furthermore, the pre-oxidation temperature is 950℃~1400℃, and the holding time is 1h~4h; the vacuum impregnation pressure is 1MPa~9MPa, the impregnation temperature is 700℃~900℃, and the holding time is 2h~4h.

[0015] Furthermore, the coarse and fine silicon carbide particles have diameters of 40 μm and 10 μm, respectively, and the binder is epoxy resin with a mass content of 15%. The printing parameters are: laser power of 8W, filling speed of 1500 mm / s, and filling thickness of 0.15 mm. The silicon carbide preform is immersed in a 15% silica sol solution for 2 hours. The holding temperature during the degreasing process is 600℃ for 1.5 hours. The pre-oxidation temperature is 1000℃ for 2 hours.

[0016] Furthermore, the coarse and fine silicon carbide particles have diameters of 90 μm and 10 μm, respectively, and the binder is phenolic resin with a binder content of 15%. The printing parameters are: laser power of 12W, filling speed of 2500 mm / s, and filling thickness of 0.2 mm. The silicon carbide preform is immersed in 20% silica sol for 4 hours. The holding temperature during the degreasing process is 800℃ for 2 hours. The pre-oxidation temperature is 1200℃ for 1.5 hours.

[0017] The present invention also provides an aluminum-based silicon carbide composite material, which is prepared by the method described above for preparing aluminum-based silicon carbide composite materials.

[0018] The present invention also provides an application of the aluminum-based silicon carbide composite material as described above in electronic packaging, aerospace, and automotive.

[0019] In summary, compared with the prior art, the aluminum-based silicon carbide composite material, its preparation method, and its application provided by the present invention have the following beneficial effects:

[0020] 1. This invention prepares SiC / Al composite materials with uniform microstructure and excellent performance by indirect printing (laser bed sintering, SLS) combined with post-processing molding. It can be seen that the surface of the SiC / Al composite material after silica sol infiltration and pre-oxidation treatment is uniform, with no obvious pore defects, and the interface between silicon carbide and aluminum alloy is good.

[0021] 2. The silica sol works in coordination with the pre-oxidation process to synergistically enhance the preform. After pre-oxidation, the nano-silica particles and the silica layer on the surface of the silicon carbide particles have an adhesive effect. Thus, the introduction of silica sol and the pre-oxidation process have an important synergistic effect. Pre-oxidation enables the silica layer generated on the surface of the silicon carbide particles to not only adhere to the nano-silica, but also protect the silicon carbide from side reactions with the aluminum alloy solution at high temperature.

[0022] 3. After degreasing, the silica sol still helps to retain the shape and strength of the silicon carbide preform, and the present invention does not require high-temperature sintering, thus eliminating a high-energy-consuming step and enabling near-net-shape forming of low-shrinkage, highly complex parts.

[0023] 4. To enable the silica sol to better penetrate into the preform, a surfactant was used to reduce the viscosity of the silica sol.

[0024] 5. The degreased silicon carbide preform contains a large amount of residual carbon, which will affect the microstructure and properties of the SiC / Al composite material. Therefore, further pre-oxidation treatment is carried out to ensure the microstructure and properties of the SiC / Al composite material.

[0025] 6. Vacuum pressure impregnation of aluminum alloy can not only remove gas from the porous silicon carbide preform, but also impregnate the molten aluminum into the vacancies generated during the binder sintering process through pressure, thereby forming a dense SiC / Al composite material. Attached Figure Description

[0026] Figure 1 This is an STL format model diagram of the aluminum-based silicon carbide reflector prepared in Example 1 of the present invention;

[0027] Figure 2 (a) and (b) in the figure respectively show the surface morphology of the SiC / Al composite material without silica sol impregnation and pre-oxidation treatment and the surface morphology of the SiC / Al composite material after silica sol impregnation and pre-oxidation treatment.

[0028] Figure 3 This is a diagram showing the flexural mechanical properties of the SiC / Al composite material prepared in Example 1 of this invention after silica sol impregnation and pre-oxidation treatment. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0030] This invention provides a method for preparing an aluminum-based silicon carbide composite material, the method mainly comprising the following steps:

[0031] Step 1: A composite powder made by mixing silicon carbide with a binder of different particle size distributions is used as raw material, and a silicon carbide blank is obtained by printing using a laser sintering device.

[0032] Specifically, firstly, silicon carbide particles of different sizes are mixed with a binder through mechanical mixing. The silicon carbide particles include coarse and fine particles, with a particle size ratio of 3:1 to 9:1. The mass percentage of coarse and fine silicon carbide powder is 40% to 90%, and the mass percentage of binder is 40% to 90%. The binder content is 5% to 20%. The binder is an organic binder such as epoxy resin, phenolic resin, or polymethyl methacrylate.

[0033] Then, a digital model of the structure to be prepared is created using 3D modeling software, and the digital model is converted into an STL file. The STL file is then imported into the selective laser sintering (SLS) equipment. The pre-lay powder bed temperature is 25℃~45℃, and the printing parameters for SLS are: laser power 6W~12W, filling speed 1500mm / s~2500mm / s, and filling thickness 0.1mm~0.2mm.

[0034] Finally, the mixture is added to a selective laser sintering (SLS) machine for printing to obtain a silicon carbide preform.

[0035] Step 2: Immerse the silicon carbide blank in a silica sol with a concentration of 10% to 30% for 2 to 4 hours, and then degrease the immersed silicon carbide blank to obtain a silicon carbide preform.

[0036] Specifically, to better penetrate the silica sol into the preform, surfactants were used. These surfactants were mainly anionic and nonionic alkylbenzene sulfonates, animal and plant proteins, and various composite surfactants that help reduce the viscosity of the silica sol. During the degreasing process, the holding temperature was 600℃~800℃, and the holding time was 1.5h~3h.

[0037] Step 3: The silicon carbide preform is subjected to pre-oxidation treatment to obtain a silicon carbide porous skeleton, and the silicon carbide porous skeleton is subjected to vacuum pressure impregnation with aluminum alloy to obtain an aluminum-based silicon carbide composite material.

[0038] Specifically, the degreased silicon carbide preform contains a large amount of residual carbon, which affects the microstructure and properties of the SiC / Al composite material. Therefore, it is necessary to perform pre-oxidation treatment. The pre-oxidation temperature is 950℃~1400℃, and the holding time is 1h~4h. The vacuum impregnation pressure is 1MPa~9MPa, the impregnation temperature is 700℃~900℃, and the holding time is 2h~4h.

[0039] The present invention also provides an aluminum-based silicon carbide composite material, which is prepared by the method described above for preparing aluminum-based silicon carbide composite materials.

[0040] The present invention also provides an application of the aluminum-based silicon carbide composite material as described above in electronic packaging, aerospace, and automotive.

[0041] The present invention will be further described in detail below with reference to specific embodiments.

[0042] Example 1

[0043] Please see Figure 1 , Figure 2 and Figure 3 In this embodiment, the SiC / Al composite material is made by using silicon carbide powder of different particle sizes and 6063Al as the main raw materials, and is formed by indirect printing (laser powder bed sintering, SLS) combined with post-processing.

[0044] In this embodiment, the SiC / Al composite material was prepared by the following method:

[0045] S1 involves mixing silicon carbide with different particle size distributions and a binder to form a composite powder, which is then added to a selective laser sintering (SLS) system for printing to obtain a silicon carbide preform. The specific steps are as follows:

[0046] (a) Silicon carbide particles of different sizes are mixed with binder by mechanical mixing. The coarse silicon carbide particles and fine silicon carbide particles have particle sizes of 40 μm and 10 μm, respectively. The binder is epoxy resin with a mass content of 15%.

[0047] (b) The complex mirror to be prepared (e.g.) Figure 1 As shown, a data model is created using 3D drawing software and converted into an STL file. This STL file is then imported into the selective laser sintering equipment.

[0048] (c) The composite powder obtained in (a) is added to a selective laser sintering (SLS) machine for printing, wherein the printing parameters are laser power of 8W, filling speed of 1500mm / s, and filling thickness of 0.15mm. After printing, the final silicon carbide mirror blank is obtained.

[0049] S2 involves immersing the silicon carbide preform in a 15% silica sol for 2 hours without applying pressure.

[0050] S3 degreases the silicon carbide preform after it has been soaked in silica sol. The holding temperature during the degreasing process is 600℃ and the holding time is 1.5h, and then a silicon carbide preform is obtained.

[0051] S4 is used to pre-oxidize the silicon carbide preform. The degreased silicon carbide preform contains a large amount of residual carbon, which will affect the microstructure and properties of the SiC / Al composite material. Therefore, it is necessary to pre-oxidize it. The pre-oxidation temperature is 1000℃ and the holding time is 2h, and then the final porous silicon carbide skeleton is obtained.

[0052] S5 involves vacuum pressure impregnation of a silicon carbide porous framework into an aluminum alloy. The vacuum impregnation pressure is 6 MPa, the impregnation temperature is 750℃, and the holding time is 2 hours to obtain the final SiC / Al composite material.

[0053] Example 2

[0054] In this embodiment, the SiC / Al composite material is made from silicon carbide powder of different particle sizes and 6063Al as the main raw materials, and is formed by indirect printing (laser powder bed sintering, SLS) combined with post-processing.

[0055] In this embodiment, the SiC / Al composite material was prepared by the following method:

[0056] S1 involves mixing silicon carbide with different particle size distributions and a binder to form a composite powder, which is then added to a selective laser sintering (SLS) system for printing to obtain a silicon carbide preform. The specific steps are as follows:

[0057] (a) Silicon carbide particles of different sizes are mixed with binder by mechanical mixing. The coarse and fine silicon carbide particles have diameters of 90 μm and 10 μm, respectively. The binder is phenolic resin with a binder content of 15%.

[0058] (b) The complex mirror to be prepared (e.g.) Figure 1 As shown, a data model is created using 3D drawing software and the data is converted into an STL file. This STL file is then imported into the selective laser sintering equipment.

[0059] (c) The composite powder obtained in (a) is added to a selective laser sintering (SLS) machine for printing, wherein the printing parameters are laser power of 12W, filling speed of 2500mm / s, and filling thickness of 0.2mm. After printing, the final silicon carbide mirror blank is obtained.

[0060] S2 involves immersing the silicon carbide preform in a 20% silica sol solution for 4 hours under vacuum.

[0061] S3 degreases the silicon carbide preform after it has been soaked in silica sol. The holding temperature during the degreasing process is 800℃ and the holding time is 2h. Then, a silicon carbide preform is obtained.

[0062] S4 pre-oxidizes the silicon carbide preform. The degreased silicon carbide preform contains a large amount of residual carbon, which will affect the microstructure and properties of the SiC / Al composite material. Therefore, it is necessary to pre-oxidize it. The pre-oxidation temperature is 1200℃ and the holding time is 1.5h, and then the final porous silicon carbide skeleton is obtained.

[0063] S5 involves vacuum pressure impregnation of a silicon carbide porous framework into an aluminum alloy. The vacuum impregnation pressure is 8 MPa, the impregnation temperature is 750℃, and the holding time is 3 h to obtain the final SiC / Al composite material.

[0064] The SiC / Al composite materials obtained through the above two embodiments have a dense structure, few defects, and a flexural strength of 371 MPa. However, the flexural strength of the SiC / Al composite material without silica sol impregnation and pre-oxidation treatment is only 245 MPa, which is significantly lower than that of the SiC / Al composite material prepared by the method provided in this invention. It can be seen that the aluminum-based silicon carbide composite material prepared by the preparation method provided in this invention has a significant performance enhancement effect and can also be used to prepare complex-shaped parts, showing great potential for industrial application.

[0065] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum-based silicon carbide composite material, characterized in that, The method includes the following steps: (1) A composite powder made by mixing silicon carbide with binder with different particle size distribution is used as raw material and printed by laser sintering equipment to obtain silicon carbide blank; (2) Immerse the silicon carbide blank in a silica sol with a concentration of 10% to 30% for 2 to 4 hours, and degrease the immersed silicon carbide blank to obtain a silicon carbide preform. (3) The silicon carbide preform is subjected to pre-oxidation treatment to obtain a silicon carbide porous skeleton, and the silicon carbide porous skeleton is subjected to vacuum pressure impregnation of aluminum alloy to obtain an aluminum-based silicon carbide composite material.

2. The method for preparing the aluminum-based silicon carbide composite material as described in claim 1, characterized in that: In step (1), firstly, silicon carbide particles of different sizes are mixed with binder by mechanical mixing; then, a digital model of the structure to be prepared is established using three-dimensional drawing software, and the digital model is converted into an STL file, and then the STL file is imported into the selective laser sintering equipment; finally, the mixture is added to the selective laser sintering equipment for printing to obtain silicon carbide blank.

3. The method for preparing the aluminum-based silicon carbide composite material as described in claim 2, characterized in that: Silicon carbide particles include coarse silicon carbide particles and fine silicon carbide particles. The particle size ratio of coarse silicon carbide particles to fine silicon carbide particles is 3:1 to 9:

1. The mass percentage of coarse silicon carbide powder is 40% to 90%, the mass percentage of fine silicon carbide powder is 40% to 90%, and the mass content of binder is 5% to 20%.

4. The method for preparing the aluminum-based silicon carbide composite material as described in claim 3, characterized in that: The pre-laid powder bed temperature is 25℃~45℃, and the printing parameters for selective laser sintering are: laser power of 6W~12W, filling speed of 1500mm / s~2500mm / s, and filling thickness of 0.1mm~0.2mm.

5. The method for preparing the aluminum-based silicon carbide composite material according to any one of claims 1-4, characterized in that: During the degreasing process, the holding temperature is 600℃~800℃, and the holding time is 1.5h~3h.

6. The method for preparing the aluminum-based silicon carbide composite material according to any one of claims 1-4, characterized in that: The pre-oxidation temperature is 950℃~1400℃, and the holding time is 1h~4h; the vacuum impregnation pressure is 1MPa~9MPa, the impregnation temperature is 700℃~900℃, and the holding time is 2h~4h.

7. The method for preparing the aluminum-based silicon carbide composite material as described in claim 3, characterized in that: The coarse and fine silicon carbide particles have diameters of 40 μm and 10 μm, respectively. The binder is epoxy resin with a mass content of 15%. The printing parameters are: laser power of 8W, filling speed of 1500 mm / s, and filling thickness of 0.15 mm. The silicon carbide preform is immersed in 15% silica sol for 2 hours. The holding temperature during the degreasing process is 600℃ for 1.5 hours. The pre-oxidation temperature is 1000℃ for 2 hours.

8. The method for preparing the aluminum-based silicon carbide composite material as described in claim 3, characterized in that: The coarse and fine silicon carbide particles have diameters of 90 μm and 10 μm, respectively. The binder is phenolic resin with a binder content of 15%. The printing parameters are: laser power of 12W, filling speed of 2500 mm / s, and filling thickness of 0.2 mm. The silicon carbide preform is immersed in 20% silica sol for 4 hours. The holding temperature during the degreasing process is 800℃ for 2 hours. The pre-oxidation temperature is 1200℃ for 1.5 hours.

9. An aluminum-based silicon carbide composite material, characterized in that: The aluminum-based silicon carbide composite material is prepared by the preparation method of the aluminum-based silicon carbide composite material according to any one of claims 1-8.

10. The application of the aluminum-based silicon carbide composite material of claim 9 in electronic packaging, aerospace, and automotive.

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