Near-net-shape fabrication method for high-volume-fraction aluminum matrix composite

Abstract

The present invention relates to a near-net-shape fabrication method for a high-volume-fraction aluminum matrix composite, and specifically relates to using compression molding and machining methods to design and fabricate a profiled ceramic preform of a specific outline structural shape on the basis of a demand for composite service components, so as to achieve the near-net-shape fabrication of the high-volume-fraction aluminum matrix composite by means of pressureless infiltration. While ensuring the performance of the composite, the present application obtains near-net-shape components of the aluminum matrix composite, and can obtain a final required component by means of a small amount of machining of a diamond milling cutter on a surface layer. The method can effectively reduce losses of raw materials and machining tools, reduce machining costs of the composite, and remarkably improve machining efficiency and the material utilization rate, achieving purposes of reducing costs and improving efficiency.

Description

A near-net-shape preparation method for high-volume aluminum-based composite materials Technical Field

[0001] The present invention relates to the field of metal matrix composite materials, and in particular to a method for preparing a high volume fraction aluminum matrix composite material by pressureless infiltration and near-net shape. Background Art

[0002] High-volume aluminum-based composite materials with a ceramic particle volume fraction higher than 50% have the advantages of low density, high strength, high modulus, low thermal expansion coefficient and high thermal conductivity. They are typical structural and functional integrated materials and are widely used in aerospace, precision instruments, electronic packaging and other fields.

[0003] Currently, the most mature method for preparing these composite parts is to first obtain a solid billet of high-volume aluminum-based composite material with a simple geometry. Then, based on lightweight design requirements, a variety of long-term precision machining methods are used to produce complex, high-precision service components. Because these components often require small batches and a wide variety of products, standardized assembly line processing is not suitable.

[0004] Due to the high content of hard ceramic particles, machining high-volume-fraction aluminum-based composites (HVFAs) is extremely challenging, requiring the use of expensive, specialized diamond milling cutters. During machining, diamond milling cutters frequently rub and collide with the hard particles, causing rapid tool wear. To ensure material precision and surface quality, the cutter must be replaced promptly, and the material removal rate must be limited. Furthermore, the material removed during machining cannot be recycled, resulting in significant material waste. For some thin-walled, box-like parts, the material utilization rate is even less than 10%. Consequently, the actual machining of precision HVFA components is plagued by significant challenges such as long processing cycles, high costs, and low material utilization. These challenges significantly limit the application of HVFAs in aerospace, precision instrumentation, and other fields, particularly hindering their widespread adoption in civilian applications. Consequently, there is an urgent need to develop targeted near-net-shape fabrication methods for HVFAs, enabling near-net-shape fabrication of complex HVFAs, while minimizing machining on mating surfaces and eliminating machining on non-mating surfaces.

[0005] The main preparation methods for high-volume aluminum-based composites include powder metallurgy and liquid infiltration. Powder metallurgy, combined with processes such as hot pressing or hot isostatic pressing, can produce high-volume aluminum-based composites with a uniform distribution of the reinforcing phase. Due to the high content of hard particles, actual service parts cannot be obtained through processing methods such as forging, extrusion, and rolling. The resulting composite material blanks must have dimensions larger than those of precision components. This results in larger composite material blanks requiring higher equipment size and pressure, resulting in a number of limitations for this process overall. Similar limitations exist for pressure infiltration. In comparison, the pressureless infiltration process does not require external pressure. Instead, the capillary forces between ceramic particles allow for spontaneous infiltration and recombination of the molten aluminum, resulting in high-volume aluminum-based composites with high density and excellent interfacial bonding. The preparation process is simple, does not require expensive equipment, and is ideal for the near-net-shape preparation of complex parts.

[0006] Obviously, as reported in the document “The influence of SiC particle shaping on the mechanical properties of high volume fraction aluminum-based composites and finite element simulation”, aluminum-based composites are prepared by natural particle stacking and pressureless infiltration. This method is not suitable for near-net-shape preparation by pressureless infiltration. Similarly, the document “Research on near-net-shape preparation and processing technology of high volume fraction SiCp / Al composites by pressureless infiltration” reports the use of hot die casting to prepare preforms with complex structures, spray coatings on the preforms, and use pressureless infiltration to prepare aluminum-based composites in near-net shape. In view of the typical characteristics of small batches, multiple varieties and diversity of aluminum-based composites, this method requires the use of special molds with different structures to obtain preforms with the desired external structure, and the process flexibility is insufficient. Patent CN202310562248.6 realizes the near-net-shape preparation of aluminum-based composite components based on powder metallurgy and hot isostatic pressing. This method requires the use of specific molds to obtain composite materials with different shapes, and is highly dependent on large-scale special equipment and molds. Therefore, it is urgently necessary to develop a low-cost near-net-shape preparation method for high-volume aluminum-based composite materials suitable for pressureless infiltration process from an engineering perspective, so as to achieve the near-net-shape preparation of high-volume aluminum-based composite materials with flexible and changeable appearance and structure. Summary of the Invention

[0007] In view of this, the present invention provides a method for preparing near-net-shape aluminum-based composite materials with high volume fraction. The main purpose is to ensure the mechanical properties of the aluminum-based composite materials while being able to prepare near-net-shape components of the aluminum-based composite materials, reduce raw material consumption, and reduce the preparation and processing cycle and cost of the aluminum-based composite materials.

[0008] The technical solution adopted by the present invention is:

[0009] A method for preparing a near-net-shape high-volume aluminum-based composite material, comprising the following steps:

[0010] a. Fully mix the ceramic powder and the binder, put them into a mold, press them into shape using a hydraulic press, and demold them to obtain a preform with a simple geometric shape;

[0011] b. Place the simple geometric shape preform prepared in step a in a blast drying oven for drying at 80-160° C. for 5-10 hours;

[0012] c. Fixing the simple geometric shape preform green body after the drying treatment in step b on a machine tool, and processing it into a special-shaped ceramic preform of the desired shape and structure using a general steel milling cutter;

[0013] d. Place the special-shaped ceramic preform processed in step c into a box-type resistance furnace, keep it at 400-600° C. for 1-3 hours to perform degumming treatment, then raise the temperature to 1100-1400° C. and keep it at that temperature for 2-5 hours, and perform high-temperature sintering treatment to obtain the special-shaped preform;

[0014] e. The shaped ceramic preform sintered at high temperature prepared in step d is placed in a graphite crucible filled with aluminum alloy, and the preform can be placed above or below the aluminum alloy. The graphite crucible is placed in a resistance furnace, and the temperature is raised to 850-1000° C. under nitrogen atmosphere. The temperature is kept for 2-4 hours to complete the pressureless infiltration process. The sample is taken out of the crucible and air-cooled to obtain a near-net-shape high-volume fraction aluminum-based composite material.

[0015] Preferably, the ceramic powder used in step a is one of silicon carbide SiC, aluminum oxide Al2O3, aluminum nitride AlN, titanium diboride TiB2, and diamond particles, and the particle size is 20-300 μm.

[0016] Preferably, the binder used in step a is a polyvinyl alcohol aqueous solution with a concentration of 5-10 wt %, and its addition amount accounts for 5-10% of the mass of the ceramic particles.

[0017] Preferably, in step a, ceramic particle grading can be used to reduce the porosity of the preform and increase the particle volume fraction.

[0018] Preferably, in step a, a hydraulic press is used for compression molding, the compression pressure is 50-150 MPa, the loading rate is 3 MPa / s, and the holding time is 1-3 min.

[0019] Preferably, the heating rate in step b is 3-5°C / min.

[0020] Preferably, in step c, the machine tool speed is controlled at 1500-2500 r / min, and the travel speed is controlled at 1-3 mm / s.

[0021] Preferably, the heating rate in step d is controlled at 4-8°C / min.

[0022] Preferably, the aluminum alloy used in step e is an Al-Mg-Si alloy, wherein the mass fraction of Mg is 3-12%, and the mass fraction of Si is 9-18%.

[0023] Preferably, nitrogen is introduced for 30 minutes before heating in step e to drive out the air in the furnace, and the nitrogen flow rate is controlled at 5-10 L / min.

[0024] Preferably, the heating rate in step e is controlled at 10-15°C / min.

[0025] Preferably, the volume fraction of the aluminum-based composite material prepared by the method of the present invention is 50-65%.

[0026] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0027] 1. The present invention utilizes compression molding, simple machining, and high-temperature sintering to produce irregularly shaped ceramic preforms with specific external structures. First, there is no need to design and manufacture complex molds; a simple-shaped ceramic preform can be pressed using a universal mold. Second, the dried, simple-shaped ceramic preform possesses sufficient strength, resists particle shedding, and can be secured to a machine tool. Excess ceramic particles can be easily removed using a universal steel milling cutter. During processing, the preform maintains the desired external structure without collapse or scattering. In other words, a irregularly shaped preform can be obtained through simple machining.

[0028] 2. The present invention adopts a common mechanical processing method to prepare a special-shaped ceramic preform. The excess ceramic particles removed during the processing can be recycled, which can reduce the consumption of raw materials.

[0029] 3. The present invention debonds and sinters the irregularly shaped preform, preventing it from collapsing or breaking apart during pressureless infiltration. Furthermore, the preform volume fraction is 50-65%, with ample intergranular spaces, ensuring sufficient aluminum liquid penetration.

[0030] 4. The present invention adopts a pressureless infiltration method to prepare a near-net-shape product of a high-volume aluminum-based composite material. The ceramic particles are evenly distributed inside the material, and the bending strength of the obtained near-net-shape sample of the high-volume aluminum-based composite material can reach above 330 MPa.

[0031] 5. This invention can design and prepare shaped ceramic preforms with specific shapes and structures based on the requirements of composite components in service, thereby achieving near-net-shape production of high-volume aluminum-based composite materials through pressureless infiltration. While maintaining the composite's performance, near-net-shape aluminum-based composite components are obtained. A minimal surface machining using a diamond milling cutter yields the desired final component. This method effectively reduces the loss of raw materials and machining tools, lowers composite material processing costs, and significantly improves processing efficiency and material utilization, ultimately achieving the goal of cost reduction and efficiency improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a physical picture of a simple cubic preform green body prepared in Example 1.

[0033] FIG2 is a physical picture of the special-shaped SiC preform of Example 1.

[0034] FIG3 is a physical picture of the near-net-shape high volume fraction SiC / Al composite material prepared in Example 1.

[0035] FIG4 is a microstructure morphology of a near-net-shape high volume fraction SiC / Al composite material prepared in Example 1.

[0036] FIG5 is a fracture morphology of a near-net-shape high volume fraction SiC / Al composite material prepared in Example 1.

[0037] FIG6 is a physical picture of the near-net-shape high volume fraction SiC / Al composite material prepared in Example 4.

[0038] FIG7 is a stress-strain curve of the near-net-shape high volume fraction SiC / Al composite material prepared in Examples 1, 2 and 6.

[0039] FIG8 is a physical picture of the simple cubic SiC / Al composite material prepared in Comparative Example 1. DETAILED DESCRIPTION

[0040] Example 1

[0041] In this example, a high-volume aluminum-based composite material was prepared in a near-net shape. The raw materials were 150 g of SiC particles with an average particle size of 80 μm and 200 g of aluminum alloy (Al-8Mg-12Si). The specific steps were as follows:

[0042] a. Thoroughly mix SiC powder with 9% polyvinyl alcohol solution, the amount of which accounts for 6% of the SiC particle mass. Place the mixed powder into a mold and press it using a hydraulic press at a pressure of 110 MPa, a loading rate of 3 MPa / s, and a holding time of 4 minutes. Demold to obtain a preform with a simple geometric shape.

[0043] b. Place the simple geometric shape preform prepared in step a in a blast drying oven for drying at a heating rate of 5°C / min and keep at 120°C for 8 hours;

[0044] c. Fixing the simple geometric shape preform green body after drying in step b on a machine tool, and using a common metal milling cutter to process it into a special-shaped ceramic preform of the desired shape and structure, with the milling cutter speed controlled at 2000 r / min and the travel speed controlled at 2 mm / s;

[0045] d. Place the special-shaped ceramic preform processed in step c into a box-type resistance furnace, heat it up to 450° C. at a rate of 7° C. / min and keep it for 2.5 hours to perform debonding treatment, then heat it up to 1150° C. at a rate of 7° C. / min and keep it for 4.5 hours to obtain a special-shaped SiC preform by high-temperature sintering;

[0046] e. The special-shaped ceramic preform sintered at high temperature prepared in step d is placed in a graphite crucible containing aluminum alloy. The preform is placed under the aluminum alloy. The graphite crucible is placed in a resistance furnace. Nitrogen is introduced for 30 minutes before heating to drive out the air in the furnace. The nitrogen rate is controlled at 10 L / min. The temperature is raised to 950° C. under nitrogen atmosphere protection and kept for 3.5 hours to complete the pressureless infiltration process. The sample is taken out of the crucible and air-cooled to obtain a near-net-shape high-volume fraction SiC / Al composite material.

[0047] In this embodiment, a SiC / Al composite material special-shaped part is prepared in a near-net shape, with a SiC body fraction of 56%. The part has a bending strength of 330 MPa and a bending modulus of 209 GPa.

[0048] Example 2

[0049] In this example, a high-volume aluminum-based composite material was prepared in a near-net shape. The raw materials were 150 g of Al2O3 particles with an average particle size of 20 μm and 200 g of aluminum alloy (Al-8Mg-12Si). The specific steps were as follows:

[0050] a. Thoroughly mix Al2O3 powder with 10% polyvinyl alcohol solution, with the added amount accounting for 5% of the Al2O3 particle mass. Place the mixed powder into a mold and press it using a hydraulic press at a pressure of 150MPa, a loading rate of 3MPa / s, and a holding time of 5 minutes. Demold to obtain a preform with a simple geometric shape.

[0051] b. Place the simple geometric shape preform prepared in step a in a blast drying oven for drying at a heating rate of 3°C / min and keep at 160°C for 5 hours;

[0052] c. Fixing the simple geometric shape preform green body after drying in step b on a machine tool, and using a general steel milling cutter to process it into a special-shaped ceramic preform of the desired shape and structure, the milling cutter speed is controlled at 2500 r / min, and the travel speed is controlled at 3 mm / s;

[0053] d. Place the special-shaped ceramic preform processed in step c into a box-type resistance furnace, heat it up at a rate of 8°C / min to 600°C and keep it for 1 hour to perform degumming treatment, then heat it up at a rate of 5°C / min to 1300°C and keep it for 3 hours, and sinter it at high temperature to obtain a special-shaped Al2O3 preform;

[0054] e. The special-shaped ceramic preform sintered at high temperature prepared in step d is placed in a graphite crucible equipped with aluminum alloy. The preform is placed above the aluminum alloy. The graphite crucible is placed in a resistance furnace. Nitrogen is introduced for 30 min before heating to drive out the air in the furnace. The nitrogen rate is controlled at 10 L / min. The temperature is raised to 1000 ° C under nitrogen atmosphere protection. The pressureless infiltration process is completed in 2 hours by insulation. The sample is taken out from the crucible and air-cooled to obtain a near-net-shape high-volume fraction Al2O3 / Al composite material.

[0055] In this embodiment, a near-net-shape Al2O3 / Al composite material special-shaped part is prepared, with an Al2O3 content of 60%. The part has a bending strength of 387 MPa and a bending modulus of 158 GPa.

[0056] Example 3

[0057] In this example, a high-volume fraction aluminum-based composite material was prepared in a near-net shape. The raw materials were 150 g of AlN particles with an average particle size of 100 μm and 200 g of aluminum alloy (Al-12Mg-16Si). The specific steps were as follows:

[0058] a. Thoroughly mix AlN powder with 8% polyvinyl alcohol solution, with the added amount accounting for 7% of the AlN particle mass. Place the mixed powder into a mold and press it using a hydraulic press at a pressure of 80 MPa, a loading rate of 3 MPa / s, and a holding time of 1 minute. Demold to obtain a preform with a simple geometric shape.

[0059] b. Place the simple geometric shape preform prepared in step a in a blast drying oven for drying at a heating rate of 5°C / min and keep at 80°C for 10 hours;

[0060] c. Fixing the simple geometric shape preform green body after drying in step b on a machine tool, and using a general steel milling cutter to process it into a special-shaped ceramic preform of the desired shape and structure, with the milling cutter speed controlled at 1500 r / min and the travel speed controlled at 1 mm / s;

[0061] d. Place the shaped ceramic preform processed in step c into a box-type resistance furnace, heat it up at a rate of 6°C / min to 550°C and hold it for 1.5 hours to perform debonding treatment, then heat it up at a rate of 4°C / min to 1400°C and hold it for 2 hours to perform high-temperature sintering treatment to obtain a shaped AlN preform;

[0062] e. The special-shaped ceramic preform sintered at high temperature prepared in step d is placed in a graphite crucible filled with aluminum alloy. The preform can be placed above or below the aluminum alloy. The graphite crucible is placed in a resistance furnace. Nitrogen is introduced for 30 minutes before heating to drive out the air in the furnace. The nitrogen rate is controlled at 10 L / min. The temperature is raised to 900° C. under nitrogen atmosphere protection and kept warm for 3.5 hours to complete the pressureless infiltration process. The sample is taken out of the crucible and air-cooled to obtain a near-net-shape high-volume fraction AlN / Al composite material.

[0063] In this embodiment, a near-net-shape AlN / Al composite material special-shaped part was prepared, with an AlN bulk fraction of 53%. The part had a bending strength of 535 MPa and a bending modulus of 198 GPa.

[0064] Example 4

[0065] In this example, a high-volume aluminum-based composite material was prepared in a near-net shape. The raw materials were 100 g of SiC particles with an average particle size of 65 μm, 50 g of SiC particles with an average particle size of 250 μm, and 200 g of aluminum alloy (Al-3Mg-14Si). The specific steps were as follows:

[0066] a. Thoroughly mix SiC powder with a 6% polyvinyl alcohol solution, the amount of which accounts for 9% of the SiC particle mass, and then add graphite powder. Place the mixed powder into a mold and press it using a hydraulic press at a pressure of 100 MPa, a loading rate of 3 MPa / s, and a holding time of 3 minutes. Demold to obtain a preform with a simple geometric shape.

[0067] b. Place the simple geometric shape preform prepared in step a in a blast drying oven for drying at a heating rate of 4°C / min and keep at 120°C for 8 hours;

[0068] c. Fixing the simple geometric shape preform green body after drying in step b on a machine tool, and using a general steel milling cutter to process it into a special-shaped ceramic preform of the desired shape and structure, with the milling cutter speed controlled at 2000 r / min and the travel speed controlled at 2 mm / s;

[0069] d. Place the special-shaped ceramic preform processed in step c into a box-type resistance furnace, heat it up to 400° C. at a rate of 6° C. / min and keep it for 3 hours to perform debonding treatment, then heat it up to 1200° C. at a rate of 7° C. / min and keep it for 4 hours to obtain a special-shaped SiC preform by high-temperature sintering;

[0070] e. The special-shaped ceramic preform sintered at high temperature prepared in step d is placed in a graphite crucible containing aluminum alloy. The preform can be placed above or below the aluminum alloy. The graphite crucible is placed in a resistance furnace. Nitrogen is introduced for 30 minutes before heating to drive out the air in the furnace. The nitrogen rate is controlled at 10 L / min. The temperature is raised to 1000° C. under nitrogen atmosphere protection and the pressureless infiltration process is completed for 2 hours. The sample is taken out of the crucible and air-cooled to obtain a near-net-shape high-volume fraction SiC / Al composite material.

[0071] In this embodiment, a SiC / Al composite special-shaped part was prepared in a near-net shape, with a SiC body fraction of 63%. The part had a bending strength of 437 MPa and a bending modulus of 166 GPa.

[0072] Example 5

[0073] In this embodiment, a high-volume aluminum-based composite material is prepared in a near-net shape. The raw materials are 100g of TiB2 particles with an average particle size of 300μm, 50g of TiB2 particles with a size of 40μm, and 200g of aluminum alloy (Al-10Mg-9Si). The specific steps are as follows:

[0074] a. Thoroughly mix the dual-size TiB2 powder with a 5% polyvinyl alcohol solution, the amount of which accounts for 10% of the TiB2 particle mass. Place the mixed powder into a mold and press it using a hydraulic press at a pressure of 130 MPa, a loading rate of 3 MPa / s, and a holding time of 2 minutes. Demold to obtain a preform with a simple geometric shape.

[0075] b. Place the simple geometric shape preform prepared in step a in a blast drying oven for drying at a heating rate of 4°C / min and keep at 160°C for 5 hours;

[0076] c. Fixing the simple geometric shape preform green body after drying in step b on a machine tool, and using a general steel milling cutter to process it into a special-shaped ceramic preform of the desired shape and structure, with the milling cutter speed controlled at 1500 r / min and the travel speed controlled at 1 mm / s;

[0077] d. Place the special-shaped ceramic preform processed in step c into a box-type resistance furnace, heat it up to 500°C at a rate of 5°C / min and keep it for 2 hours to perform degumming treatment, then heat it up to 1100°C at a rate of 8°C / min and keep it for 5 hours to obtain a special-shaped TiB2 preform by high-temperature sintering;

[0078] e. The special-shaped ceramic preform sintered at high temperature prepared in step d is placed in a graphite crucible equipped with aluminum alloy. The preform is placed above or below the aluminum alloy. Nitrogen is introduced for 30 min before heating to drive out the air in the furnace. The nitrogen rate is controlled at 10 L / min. The graphite crucible is placed in a resistance furnace. The temperature is raised to 850 ° C under nitrogen atmosphere protection. The pressureless infiltration process is completed in 4 hours by insulation. The sample is taken out from the crucible and air-cooled to obtain a near-net-shape high-volume fraction TiB2 / Al composite material.

[0079] In this embodiment, a near-net-shape TiB2 / Al composite material special-shaped part is prepared, with a TiB2 bulk fraction of 65%. The part has a bending strength of 536 MPa and a bending modulus of 183 GPa.

[0080] Example 6

[0081] In this example, a high-volume aluminum-based composite material was prepared in a near-net shape. The raw materials were 150 g of diamond particles with an average particle size of 120 μm and 200 g of aluminum alloy (Al-9Mg-18Si). The specific steps were as follows:

[0082] a. Thoroughly mix diamond powder with 7% polyvinyl alcohol solution, with the added amount accounting for 8% of the mass of the diamond particles. Place the mixed powder into a mold and press it using a hydraulic press at a pressure of 50 MPa, a loading rate of 3 MPa / s, and a holding time of 3 minutes. Demold to obtain a preform with a simple geometric shape;

[0083] b. Place the simple geometric shape preform prepared in step a in a blast drying oven for drying at a heating rate of 5°C / min and keep at 80°C for 10 hours;

[0084] c. Fixing the simple geometric shape preform green body after drying in step b on a machine tool, and using a general steel milling cutter to process it into a special-shaped ceramic preform of the desired shape and structure, the milling cutter speed is controlled at 2500 r / min, and the travel speed is controlled at 3 mm / s;

[0085] d. Place the special-shaped ceramic preform processed in step c into a box-type resistance furnace, heat it up to 400° C. at a rate of 4° C. / min and keep it for 3 hours to perform degumming treatment, then heat it up to 1400° C. at a rate of 4° C. / min and keep it for 2 hours to perform high-temperature sintering treatment to obtain a special-shaped diamond preform;

[0086] e. The special-shaped ceramic preform sintered at high temperature prepared in step d is placed in a graphite crucible containing aluminum alloy. The preform can be placed above or below the aluminum alloy. The graphite crucible is placed in a resistance furnace. Nitrogen is introduced for 30 minutes before heating to drive out the air in the furnace. The nitrogen rate is controlled at 10 L / min. The temperature is raised to 950° C. under nitrogen atmosphere protection and the pressureless infiltration process is completed after insulation for 3 hours. The sample is taken out from the crucible and air-cooled to obtain a near-net-shape high-volume fraction diamond-reinforced aluminum-based composite material.

[0087] In this embodiment, a diamond-reinforced aluminum-based composite material special-shaped part was prepared in a near-net shape, with a diamond body fraction of 50%. The part had a bending strength of 553 MPa and a bending modulus of 243 GPa.

[0088] Comparative Example 1

[0089] The same raw materials and preparation process as in Example 1 were used, but the ceramic preform was not machined. The composite material prepared in the comparative example was a regular cube, having the same height and base area as the composite material in Example 1.

[0090] Comparative Example 2

[0091] An aluminum-based composite material was prepared by using the method reported in the literature "Effect of SiC particle shaping on the mechanical properties of high-volume aluminum-based composites and finite element simulation", combining natural particle stacking and pressureless infiltration. The composite material has the same height and bottom area as the composite material in Example 1.

[0092] Clearly, processing the regular cubic composite materials prepared in Comparative Examples 1 and 2 into the shape of Example 1 requires the use of a specialized diamond milling cutter to gradually remove 53% of the composite material, resulting in a material utilization rate of approximately 47%. If more complex composite components are to be processed, the material utilization rate will be further reduced. Furthermore, the removed composite material cannot be reused, resulting in a waste of raw materials and energy.

[0093] By comparison, the advantages of the near-net-shape aluminum-based composite materials obtained in Examples 1-6 are that they can not only reduce the consumption of raw materials, but also only require simple surface processing to obtain the final required composite material special-shaped components, and the material utilization rate is above 90%.

Claims

1. A near-net-shape preparation method for high-volume-fraction aluminum matrix composites, characterized in that: The specific steps are as follows: a. Thoroughly mix the ceramic powder with the binder, place it in a mold, and use a hydraulic press to form it. After demolding, a preform green body with a simple geometric shape is obtained; b. Place the preform green body with a simple geometric shape prepared in step a in a blast drying oven for drying treatment, and keep it at 80 - 160 °C for 5 - 10 h; c. Fix the preform green body with a simple geometric shape after drying treatment in step b on a machine tool, and use a general steel milling cutter to process it into a special-shaped ceramic preform with the required outer shape structure; d. Place the special-shaped ceramic preform processed in step c in a box-type resistance furnace. According to different binders, keep it at 400 - 600 °C for 1 - 3 hours for debinding treatment, and then raise the temperature to 1100 - 1400 °C and keep it for 2 - 5 hours for high-temperature sintering treatment to obtain a special-shaped preform; e. Place the high-temperature sintered special-shaped ceramic preform prepared in step d in a graphite crucible containing aluminum alloy. The preform can be placed above or below the aluminum alloy. Place the graphite crucible in a resistance furnace, heat it up to 850 - 1000 °C under the protection of a nitrogen atmosphere, and keep it for 2 - 4 hours to complete the pressureless infiltration process. Take the sample out of the crucible and air-cool it to obtain a near-net-shaped high-volume-fraction aluminum matrix composite.

2. A near-net-shape preparation method of a high-volume-fraction aluminum matrix composite according to claim 1, characterized in that: The ceramic powder used in step a is one of silicon carbide SiC, aluminum oxide Al2O3, aluminum nitride AlN, titanium diboride TiB2, and diamond particles, and the particle size is 20 - 300 μm.

3. A near-net-shape preparation method of a high-volume-fraction aluminum matrix composite material according to claim 1, characterized in that: The binder used in step a is an aqueous solution of polyvinyl alcohol, with a concentration of 5 - 10 wt%, and its addition amount accounts for 3 - 10% of the mass of the ceramic particles.

4. A near-net-shape preparation method for a high-volume-fraction aluminum matrix composite according to claim 1, characterized in that: In step a, the porosity of the preform can be reduced and the particle volume fraction can be increased by using the method of ceramic particle gradation.

5. A near-net-shape preparation method of a high-volume-fraction aluminum matrix composite material according to claim 1, characterized in that: In step a, a hydraulic press is used for forming, the pressing pressure is 50 - 150 MPa, the loading speed is 3 MPa / s, and the pressure holding time is 1 - 3 min.

6. A near-net-shape preparation method of a high-volume-fraction aluminum matrix composite according to claim 1, characterized in that: In step b, the heating rate is 3 - 5 °C / min.

7. A near-net-shape preparation method for a high-volume-fraction aluminum matrix composite according to claim 1, characterized in that: In step c, the machine tool rotation speed is controlled at 1500 - 2500 r / min, and the traveling speed is controlled at 1 - 3 mm / s.

8. A near-net-shape preparation method of a high-volume-fraction aluminum matrix composite according to claim 1, characterized in that: In step d, the heating rate is controlled at 4 - 8 °C / min.

9. A near-net-shape preparation method of a high-volume-fraction aluminum matrix composite according to claim 1, characterized in that: The aluminum alloy used in step e is a self-made Al-Mg-Si alloy, and the mass fractions of Mg and Si are 3 - 12% and 9 - 18% respectively.

10. A near-net-shape preparation method of a high volume fraction aluminum matrix composite according to claim 1, characterized in that: In step e, nitrogen is introduced for 30 min before heating to expel the air in the furnace, and the nitrogen speed is controlled at 5 - 10 L / min.

11. A near-net-shape preparation method of a high-volume-fraction aluminum matrix composite material according to claim 1, characterized in that: In step e, the heating rate is controlled at 10 - 15 °C / min.

12. A near-net shape preparation method for high volume fraction aluminum matrix composites according to claim 1, characterized in that: The volume fraction of the aluminum matrix composite prepared by the method of the present invention is 50 - 65%.

Images