Method for near-net forming of high-precision and high-density metal matrix composite complex component through built-in core mold

Abstract

The invention discloses a method for near-net forming of a high-precision and high-density metal-based composite material complex component with a built-in core mold, and relates to a preparation method for near-net forming of a metal-based composite material complex component. In order to solve the problem of low density in near-net forming of the metal-based composite material complex component, the high-precision and high-density metal-based composite material complex component is obtained through near-net forming by combining gypsum mold precision casting and a self-exhaust pressure infiltration technology. According to the method, the advantage that the high precision of gypsum mold precision casting and the advantage that a high-density composite material can be prepared through a pressure infiltration technology are combined, a core mold is placed in a composite material prefabricated body, then the composite material containing the core mold is prepared through a pressure infiltration method, finally core mold removing treatment is conducted, and finally the high-precision and high-density metal matrix composite material complex component is obtained. And the production requirements of various complex components can be met, the production cost is reduced, the production efficiency is improved, the application range is wide, and the application prospect is high.

Description

Technical Field

[0001] The invention relates to the technical field of composite material preparation, and in particular to a method for preparing a near-net-shape complex component of a metal-based composite material. Background Art

[0002] Metal matrix composites have high specific strength and specific stiffness, as well as good wear resistance and corrosion resistance. Some metal matrix composites also have the advantages of high thermal conductivity, high temperature resistance and excellent dimensional stability. They have been widely used in aerospace, advanced weapons, electronics and transportation. These excellent properties are due to the various reinforcing phases inside the composites. According to the different forms of the reinforcing phases, metal matrix composites can be mainly divided into three categories: fiber reinforcement, particle reinforcement and whisker reinforcement. Fiber-reinforced metal matrix composites such as Cf / Al have high specific strength, strong corrosion resistance and excellent fatigue resistance, but the presence of carbon fibers inside them has high requirements for the processing methods of material components; particle-reinforced metal matrix composites such as SiCp / Al, Be / Al, Diamond / Cu, etc., have various reinforcing phases inside that improve the various properties of the composites, but at the same time, the brittleness and hardness of the reinforcing phases also increase the difficulty and cost of material processing, which makes it difficult to reduce the manufacturing cost of various metal matrix composite complex components and difficult to achieve mass production. Therefore, various near-net shaping technologies have received a lot of attention in recent years. They can directly prepare composite components with complex shapes through different methods, which is a hot topic in the current research field of composite materials.

[0003] At present, there are few research reports on the near-net-shape preparation technology of metal matrix composite materials in China. The main preparation methods are: precision casting, powder metallurgy, additive manufacturing technology, powder injection molding and superplastic forming technology. The reinforcing phase in the metal matrix composite material will affect the fluidity and filling capacity of the melt. The composite material obtained by precision casting has many defects such as looseness and shrinkage, and the molding effect is poor; the powder metallurgy process is complex and the cost is high. The raw material powder has a great influence on the quality of the composite material, and it is difficult to achieve mass production of high-quality components; additive manufacturing technology is a near-net-shape forming technology that has developed rapidly in recent years, but the materials obtained by additive manufacturing have defects such as pores and voids inside, and are also easy to induce the reaction between the reinforcing phase and the matrix, making the quality reliability of the component low; powder injection molding can realize the preparation of complex components, but the incomplete volatilization of the binder in the preparation process will lead to the formation of pores inside the material, which will reduce the performance and reliability of the component; it can be seen that the near-net-shape forming technology of high-density composite components is still imperfect, and it is urgent to develop a new low-cost, high-density, and near-net-shape forming technology for composite materials that can realize batch preparation of complex shapes. Summary of the invention

[0004] In order to solve the problem of low density in near-net-form molding of complex components of metal-based composite materials, the present invention combines gypsum mold precision casting and self-exhaust pressure infiltration technology to obtain high-precision and high-density complex components of metal-based composite materials through near-net-form molding.

[0005] The method for near-net-shape forming of a complex component of a metal-based composite material with a built-in core mold according to the present invention is carried out in the following steps:

[0006] 1. Weighing of reinforcement phase and metal matrix:

[0007] Weighing the reinforcing phase and metal matrix required for preparing the composite material and drying them;

[0008] The reinforcing phase in step 1 is SiC particles, B4C particles, Al2O3 particles, Be powder or diamond particles;

[0009] The metal substrate in step 1 is pure aluminum, pure copper, aluminum alloy or copper alloy;

[0010] 2. Manufacture of core mold:

[0011] A certain mass of gypsum powder is weighed and mixed with water, and then fillers are added, and then the slurry after being evenly mixed is poured into a predetermined mold for forming a core mold for molding, and after demoulding, drying pretreatment is performed to obtain a core mold for molding complex components of metal matrix composite materials;

[0012] Step 2: the filler is carbon fiber, BN powder or BN fiber; the amount of filler added is 3-9% of the total volume of the mixture of gypsum powder and water;

[0013] 3. Preform cold pressing:

[0014] The reinforcing phase and the core mold weighed in step 1 are placed into a forming mold of a complex component of a metal matrix composite material, and cold-pressed to obtain a composite material preform;

[0015] The cold pressing pressure in step 3 is 0.5-20 MPa, the pressing speed is 0.1-3 mm / min, and the holding time is 1-3 min;

[0016] 4.Pressure infiltration preparation of composite materials:

[0017] The preform obtained in step 3 is placed in a heating furnace together with the mold, and the preform and the mold are preheated under a protective atmosphere; at the same time, the metal matrix weighed in step 1 is heated to melt under a protective atmosphere; the preform and the mold are taken out and placed on a press, and the molten metal matrix is ​​poured in, and then pressure infiltration is performed, and after the infiltration is completed, it is cooled to room temperature, and then demolded to obtain a composite material containing a core mold;

[0018] The melting temperature of the metal matrix in step 4 is 100 to 250° C. above the melting point;

[0019] The pressure applied during the pressure infiltration process in step 4 is 15 to 40 kN, and the pressure holding time is 3 to 10 minutes;

[0020] 5. Core-removal treatment of composite materials containing core molds:

[0021] The composite material containing the core mold obtained in step 4 is subjected to mechanical de-gypsum treatment, and then the composite material is placed in a gypsum dissolving agent, and ultrasonic waves are applied to remove the residual gypsum on the surface. Finally, the composite material is cleaned and dried.

[0022] The present invention has the following beneficial effects:

[0023] 1. The method of the present invention provides a new idea for the near-net-shape forming of complex components of metal-based composite materials. It combines the advantages of high precision of gypsum mold precision casting and pressure infiltration technology to prepare high-density composite materials. The core mold is placed in the composite material preform, and then the composite material containing the core mold is obtained by pressure infiltration. Finally, the core mold is removed to finally obtain a high-precision, high-density complex component of metal-based composite materials.

[0024] 2. The present invention utilizes the advantages of good fluidity and filling properties of gypsum to produce various complex and high-precision core molds, such as thin-walled structures, multi-stage structures or structures containing reinforcing ribs, which can meet the production needs of various complex components.

[0025] 3. The present invention cold presses the reinforcement phase into a component shape by means of a core mold and a mold at room temperature, which has low requirements on the pressing equipment, and is conducive to reducing production costs and improving production efficiency;

[0026] 4. The present invention can prepare composite components of different types and different metal matrices. The performance of complex components can be adjusted by simply changing the type of reinforcement phase or the type and content of elements in the molten metal matrix. It has a wide range of applications and high application prospects.

[0027] 5. The process of the present invention is simple, easy to operate, does not require the use of chemical reagents that are harmful to the environment, is energy-saving and environmentally friendly, has low cost, and is easy to realize industrial production and application.

[0028] 6. The performance of the complex components of the metal-based composite materials prepared by the present invention meets the use requirements, the material performance is high, the preparation cycle is short, and the price is greatly reduced, which can better meet the market demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a macroscopic photograph of the Al2O3 / 2024Al composite material component prepared in Example 1;

[0030] Figure 2This is a microstructure photograph of the Al2O3 / 2024Al composite material component prepared in Example 1;

[0031] Figure 3 This is a microstructure photograph of the SiCp / 2024Al composite material component prepared in Example 2;

[0032] Figure 4 This is a microstructure photograph of the Be / 6061Al composite material component prepared in Example 3. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any reasonable combination of the specific implementation modes.

[0034] Specific implementation method 1: The method of near-net-shape forming of high-precision and high-density metal-based composite complex components with built-in mandrel in this implementation method is carried out in the following steps:

[0035] 1. Weighing of reinforcement phase and metal matrix:

[0036] Weighing the reinforcing phase and metal matrix required for preparing the composite material and drying them;

[0037] The reinforcing phase in step 1 is SiC particles, B4C particles, Al2O3 particles, Be powder or diamond particles;

[0038] The metal substrate in step 1 is pure aluminum, pure copper, aluminum alloy or copper alloy;

[0039] 2. Manufacture of core mold:

[0040] A certain mass of gypsum powder is weighed and mixed with water, and then fillers are added, and then the slurry after being evenly mixed is poured into a predetermined mold for forming a core mold for molding, and after demoulding, drying pretreatment is performed to obtain a core mold for molding complex components of metal matrix composite materials;

[0041] Step 2: the filler is carbon fiber, BN powder or BN fiber; the amount of filler added is 3-9% of the total volume of the mixture of gypsum powder and water;

[0042] 3. Preform cold pressing:

[0043] The reinforcing phase and the core mold weighed in step 1 are placed into a forming mold of a complex component of a metal matrix composite material, and cold-pressed to obtain a composite material preform;

[0044] The cold pressing pressure in step 3 is 0.5-20 MPa, the pressing speed is 0.1-3 mm / min, and the holding time is 1-3 min;

[0045] 4.Pressure infiltration preparation of composite materials:

[0046] The preform obtained in step 3 is placed in a heating furnace together with the mold, and the preform and the mold are preheated under a protective atmosphere; at the same time, the metal matrix weighed in step 1 is heated to melt under a protective atmosphere; the preform and the mold are taken out and placed on a press, and the molten metal matrix is ​​poured in, and then pressure infiltration is performed, and after the infiltration is completed, it is cooled to room temperature, and then demolded to obtain a composite material containing a core mold;

[0047] The melting temperature of the metal matrix in step 4 is 100 to 250° C. above the melting point;

[0048] The pressure applied during the pressure infiltration process in step 4 is 15 to 40 kN, and the pressure holding time is 3 to 10 minutes;

[0049] 5. Core-removal treatment of composite materials containing core molds:

[0050] The composite material containing the core mold obtained in step 4 is subjected to mechanical de-gypsum treatment, and then the composite material is placed in a gypsum dissolving agent, and ultrasonic waves are applied to remove the residual gypsum on the surface. Finally, the composite material is cleaned and dried.

[0051] This implementation has the following beneficial effects:

[0052] 1. The method of this embodiment provides a new idea for the near-net forming of complex components of metal-based composite materials. It combines the advantages of high precision of gypsum mold precision casting and pressure infiltration technology to prepare high-density composite materials. The core mold is placed in the composite material preform, and then the composite material containing the core mold is obtained by pressure infiltration. Finally, the core mold is removed to finally obtain a high-precision, high-density complex component of metal-based composite materials.

[0053] 2. This embodiment utilizes the advantages of good fluidity and filling properties of gypsum to produce various complex shapes and high-precision core molds, such as thin-walled structures, multi-stage structures or structures with reinforcing ribs, which can meet the production needs of various complex components.

[0054] 3. In this embodiment, the cold pressing of the reinforcement phase into the shape of the component by the core mold and the mold only needs to be carried out at room temperature, which has low requirements on the pressing equipment, is conducive to reducing production costs and improving production efficiency;

[0055] 4. This embodiment can prepare composite components of different types and different metal matrices. The performance of complex components can be adjusted by simply changing the type of reinforcement phase or the type and content of elements in the molten metal matrix. It has a wide range of applications and high application prospects.

[0056] 5. The process method of this embodiment is simple, easy to operate, does not require the use of chemical reagents that are harmful to the environment, is energy-saving and environmentally friendly, has low cost, and is easy to realize industrial production and application.

[0057] 6. The performance of the complex metal-based composite material components prepared in this embodiment meets the use requirements, the material performance is high, the preparation cycle is short, and the price is greatly reduced, which can better meet the market demand.

[0058] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that: the particle size of the reinforcement phase in step 1 is 50nm to 100μm.

[0059] Specific implementation method three: This implementation method is different from specific implementation methods one or two in that: the volume of the reinforcement phase in step one is 40-60% of the volume of the composite material.

[0060] Specific implementation method 4: This implementation method is different from any one of specific implementation methods 1 to 3 in that: the metal matrix composite material complex component described in step 2 is a thin-walled structure or has one or more shapes such as grooves, edges and corners, and curved surfaces.

[0061] Specific implementation method five: This implementation method is different from any one of specific implementation methods one to four in that the mass ratio of water to gypsum powder in step two is (0.4-0.5):1.

[0062] Specific embodiment 6: This embodiment is different from specific embodiments 1 to 5 in that: the drying pretreatment in step 2 is drying or multi-stage roasting; the drying process is: keeping warm at 150-250°C for 2-4h, and the heating rate is 2.5-5°C / min; the multi-stage roasting process is: keeping warm at 80-100°C for 7.5-8.5h, heating to 145-155°C for 3.5-4.5h, and heating Heat to 245-255℃ and keep warm for 1.5-2.5h, heat to 345-355℃ and keep warm for 1.5-2.5h, heat to 445-455℃ and keep warm for 1.5-2.5h, heat to 545-555℃ and keep warm for 0.5-1.5h, heat to 650-700℃ and keep warm for 1.5-2.5h, cool the furnace to 200-300℃ and keep warm for 2-3h, the heating rate is 2.5-5℃ / min.

[0063] Specific implementation method seven: This implementation method is different from any one of specific implementation methods one to six in that: the protective atmosphere in step four is a nitrogen atmosphere, an argon atmosphere or a helium atmosphere.

[0064] Specific implementation eight: This implementation differs from any one of specific implementations one to seven in that: the preheating temperature in step four is 400-600° C., and the time is 2-3 hours.

[0065] Specific implementation method 9: This implementation method is different from any one of specific implementation methods 1 to 8 in that: the cooling rate in step 4 is 20 to 40° C. / h.

[0066] Specific implementation method ten: This implementation method is different from any one of specific implementation methods one to nine in that: the mechanical plaster removal process in step five is a turning process or a milling process.

[0067] Example 1

[0068] The method for near-net-shape forming of a complex component of a metal matrix composite material with a built-in core mold in this embodiment is carried out in the following steps:

[0069] 1. Weighing of reinforcement phase and metal matrix:

[0070] Weighing the reinforcing phase and metal matrix required for preparing the composite material and drying them;

[0071] The reinforcing phase in step 1 is Al2O3 particles;

[0072] The metal substrate in step 1 is 2024 aluminum alloy;

[0073] The particle size of the reinforcing phase in step 1 is 45 μm;

[0074] The volume of the reinforcement phase in step 1 is 45% of the volume of the composite material;

[0075] 2. Manufacture of core mold:

[0076] A certain mass of gypsum powder is weighed and mixed with water, and then fillers are added, and then the slurry after being evenly mixed is poured into a predetermined mold for forming a core mold for molding, and after demoulding, drying pretreatment is performed to obtain a core mold for molding complex components of metal matrix composite materials;

[0077] Step 2: the surface of the metal matrix composite material complex component has reinforcing ribs, and the reinforcing ribs are curved surfaces;

[0078] The mass ratio of water to gypsum powder in step 2 is 0.51;

[0079] The filler in step 2 is BN powder; the amount of filler added is 6% of the total volume of the mixture of gypsum powder and water;

[0080] The drying pretreatment in step 2 is drying; the drying process is: keeping at 200°C for 3 hours, with a heating rate of 3°C / min;

[0081] 3. Preform cold pressing:

[0082] The reinforcing phase and the core mold weighed in step 1 are placed into a forming mold of a complex component of a metal matrix composite material, and cold-pressed to obtain a composite material preform;

[0083] The cold pressing pressure in step 3 is 5 MPa, the pressing speed is 0.5 mm / min, and the holding time is 3 min;

[0084] 4.Pressure infiltration preparation of composite materials:

[0085] The preform obtained in step 3 is placed in a heating furnace together with the mold, and the preform and the mold are preheated under a protective atmosphere; at the same time, the metal matrix weighed in step 1 is heated to melt under a protective atmosphere; the preform and the mold are taken out and placed on a press, and the molten metal matrix is ​​poured in, and then pressure infiltration is performed, and after the infiltration is completed, it is cooled to room temperature, and then demolded to obtain a composite material containing a core mold;

[0086] The protective atmosphere in step 4 is a nitrogen atmosphere;

[0087] The preheating temperature in step 4 is 500°C and the time is 2h;

[0088] The melting temperature of the metal matrix in step 4 is 150° C. above the melting point;

[0089] The cooling rate in step 4 is 30°C / h;

[0090] The pressure applied during the pressure infiltration process in step 4 is 20 kN, and the holding time is 5 min;

[0091] 5. Core-removal treatment of composite materials containing core molds:

[0092] The composite material containing the core mold obtained in step 4 is subjected to mechanical de-gypsum treatment, and then the composite material is placed in a gypsum dissolving agent, and ultrasonic waves are applied to remove the residual gypsum on the surface. Finally, the composite material is cleaned and dried.

[0093] The mechanical plaster removal process described in step 5 is lathe processing.

[0094] The Al2O3 / 2024Al composite material component prepared according to Example 1 was tested to have a density of 99.6% and a surface roughness Ra of 3.2 μm. The density indicates that there are no obvious holes inside the component material, and the surface roughness has reached the use requirements of complex composite components. Combined with the microstructure photos, it can be seen that the reinforcement phase is evenly distributed in the material, achieving near-net forming of the complex structure of the metal matrix composite material. Figure 1 This is a macroscopic photograph of the Al2O3 / 2024Al composite material component prepared in Example 1; it can be seen that the composite material component has high molding accuracy and the 1 mm reinforcement ribs are well molded. Figure 2 This is a microstructure photograph of the Al2O3 / 2024Al composite material component prepared in Example 1; it can be found that the matrix 2024Al can be well infiltrated into the Al2O3 without obvious holes, and the Al2O3 reinforcement phase is evenly distributed without obvious segregation, which can meet the current near-net molding requirements of complex composite structures.

[0095] Example 2

[0096] The method for near-net-shape forming of a complex component of a metal matrix composite material with a built-in core mold in this embodiment is carried out in the following steps:

[0097] 1. Weighing of reinforcement phase and metal matrix:

[0098] Weighing the reinforcing phase and metal matrix required for preparing the composite material and drying them;

[0099] The reinforcing phase in step 1 is SiC particles;

[0100] The metal substrate in step 1 is 2024 aluminum alloy;

[0101] The particle size of the reinforcing phase in step 1 is 5 μm;

[0102] The volume of the reinforcement phase in step 1 is 45% of the volume of the composite material;

[0103] 2. Manufacture of core mold:

[0104] A certain mass of gypsum powder is weighed and mixed with water, and then fillers are added, and then the slurry after being evenly mixed is poured into a predetermined mold for forming a core mold for molding, and after demoulding, drying pretreatment is performed to obtain a core mold for molding complex components of metal matrix composite materials;

[0105] The metal matrix composite material complex component in step 2 is a thin-walled structure;

[0106] The mass ratio of water to gypsum powder in step 2 is 0.4:1;

[0107] The filler in step 2 is BN powder; the amount of filler added is 6% of the total volume of the mixture of gypsum powder and water;

[0108] Step 2: The drying pretreatment is drying; the drying process is: keeping at 200°C for 3 hours, with a heating rate of 4°C / min;

[0109] 3. Preform cold pressing:

[0110] The reinforcing phase and the core mold weighed in step 1 are placed into a forming mold of a complex component of a metal matrix composite material, and cold-pressed to obtain a composite material preform;

[0111] The cold pressing pressure in step 3 is 15 MPa, the pressing speed is 1 mm / min, and the holding time is 2 min;

[0112] 4.Pressure infiltration preparation of composite materials:

[0113] The preform obtained in step 3 is placed in a heating furnace together with the mold, and the preform and the mold are preheated under a protective atmosphere; at the same time, the metal matrix weighed in step 1 is heated to melt under a protective atmosphere; the preform and the mold are taken out and placed on a press, and the molten metal matrix is ​​poured in, and then pressure infiltration is performed, and after the infiltration is completed, it is cooled to room temperature, and then demolded to obtain a composite material containing a core mold;

[0114] The protective atmosphere in step 4 is argon atmosphere;

[0115] The preheating temperature in step 4 is 550°C and the time is 2.5h;

[0116] The melting temperature of the metal matrix in step 4 is 200° C. above the melting point;

[0117] The cooling rate in step 4 is 20°C / h;

[0118] The pressure applied during the pressure infiltration process in step 4 is 30 kN, and the holding time is 6 min;

[0119] 5. Core-removal treatment of composite materials containing core molds:

[0120] The composite material containing the core mold obtained in step 4 is subjected to mechanical de-gypsum treatment, and then the composite material is placed in a gypsum dissolving agent, and ultrasonic waves are applied to remove the residual gypsum on the surface. Finally, the composite material is cleaned and dried.

[0121] The mechanical plaster removal process described in step 5 is lathe processing.

[0122] The SiCp / 2024Al composite material component prepared in Example 2 was tested to have a density of 99.1% and a surface roughness Ra of 4.6 μm. The density indicates that there are no obvious holes inside the component material, and its surface roughness has met the requirements for the use of complex composite components. Figure 3 It can be seen that the reinforcement phase is evenly distributed in the material, achieving near-net forming of the complex structure of the metal matrix composite material.

[0123] Example 3

[0124] The method for near-net-shape forming of a complex component of a metal matrix composite material with a built-in core mold in this embodiment is carried out in the following steps:

[0125] 1. Weighing of reinforcement phase and metal matrix:

[0126] Weighing the reinforcing phase and metal matrix required for preparing the composite material and drying them;

[0127] The reinforcing phase in step 1 is Be powder;

[0128] The metal substrate in step 1 is 6061 aluminum alloy;

[0129] The particle size of the reinforcing phase in step 1 is 10 μm;

[0130] The volume of the reinforcement phase in step 1 is 60% of the volume of the composite material;

[0131] 2. Manufacture of core mold:

[0132] A certain mass of gypsum powder is weighed and mixed with water, and then fillers are added, and then the slurry after being evenly mixed is poured into a predetermined mold for forming a core mold for molding, and after demoulding, drying pretreatment is performed to obtain a core mold for molding complex components of metal matrix composite materials;

[0133] Step 2: The metal matrix composite material complex component is a thin-walled structure with reinforcing ribs, and the reinforcing ribs are curved surfaces.

[0134] The mass ratio of water to gypsum powder in step 2 is 0.45:1;

[0135] The filler in step 2 is BN powder; the amount of filler added is 6% of the total volume of the mixture of gypsum powder and water;

[0136] The drying pretreatment in step 2 is multi-stage roasting; the multi-stage roasting process is: keep warm at 90°C for 8h, heat to 150°C for 4h, heat to 250°C for 2h, heat to 350°C for 2h, heat to 450°C for 2h, heat to 550°C for 1h, heat to 680°C for 2h, furnace cooling to 250°C for 2.5h, and the heating rate is 3°C / min;

[0137] 3. Preform cold pressing:

[0138] The reinforcing phase and the core mold weighed in step 1 are placed into a forming mold of a complex component of a metal matrix composite material, and cold-pressed to obtain a composite material preform;

[0139] The cold pressing pressure in step 3 is 10 MPa, the pressing speed is 1.5 mm / min, and the holding time is 3 min;

[0140] 4.Pressure infiltration preparation of composite materials:

[0141] The preform obtained in step 3 is placed in a heating furnace together with the mold, and the preform and the mold are preheated under a protective atmosphere; at the same time, the metal matrix weighed in step 1 is heated to melt under a protective atmosphere; the preform and the mold are taken out and placed on a press, and the molten metal matrix is ​​poured in, and then pressure infiltration is performed, and after the infiltration is completed, it is cooled to room temperature, and then demolded to obtain a composite material containing a core mold;

[0142] The protective atmosphere in step 4 is a nitrogen atmosphere;

[0143] The preheating temperature in step 4 is 600°C and the time is 3h;

[0144] The melting temperature of the metal matrix in step 4 is 200° C. above the melting point;

[0145] The cooling rate in step 4 is 20°C / h;

[0146] The pressure applied during the pressure infiltration process in step 4 is 40 kN, and the holding time is 5 min;

[0147] 5. Core-removal treatment of composite materials containing core molds:

[0148] The composite material containing the core mold obtained in step 4 is subjected to mechanical de-gypsum treatment, and then the composite material is placed in a gypsum dissolving agent, and ultrasonic waves are applied to remove the residual gypsum on the surface. Finally, the composite material is cleaned and dried.

[0149] The mechanical plaster removal process described in step 5 is lathe processing.

[0150] The Be / 6061Al composite material component prepared according to Example 3 was tested to have a density of 99.4% and a surface roughness Ra of 4.3 μm. The density indicates that there are no obvious holes inside the component material, and its surface roughness has met the use requirements of complex composite components. Combined with the microstructure photos Figure 4 It can be seen that the reinforcement phase is evenly distributed in the material, achieving near-net forming of the complex structure of the metal matrix composite material.

Claims

1. A method for near-net-shape forming of high-precision and high-density complex metal matrix composite components with an internal core mold, characterized in that: The method for near-net-shape forming of high-precision and high-density metal matrix composite complex components with built-in core mold is carried out in the following steps:

1. Weighing of reinforcement phase and metal matrix: Weighing the reinforcing phase and metal matrix required for preparing the composite material and drying them; The reinforcing phase in step 1 is SiC particles, B4C particles, Al2O3 particles, Be powder or diamond particles; The metal substrate in step 1 is pure aluminum, pure copper, aluminum alloy or copper alloy; 2. Manufacture of core mold: A certain mass of gypsum powder is weighed and mixed with water, and then fillers are added, and then the slurry after being evenly mixed is poured into a predetermined mold for forming a core mold for molding, and after demoulding, drying pretreatment is performed to obtain a core mold for molding complex components of metal matrix composite materials; Step 2: the filler is carbon fiber, BN powder or BN fiber; the amount of filler added is 3-9% of the total volume of the mixture of gypsum powder and water; 3. Preform cold pressing: The reinforcing phase and the core mold weighed in step 1 are placed into a forming mold of a complex component of a metal matrix composite material, and cold-pressed to obtain a composite material preform; The cold pressing pressure in step 3 is 0.5-20 MPa, the pressing speed is 0.1-3 mm / min, and the holding time is 1-3 min; 4.Pressure infiltration preparation of composite materials: The preform obtained in step 3 is placed in a heating furnace together with the mold, and the preform and the mold are preheated under a protective atmosphere; at the same time, the metal matrix weighed in step 1 is heated to melt under a protective atmosphere; the preform and the mold are taken out and placed on a press, and the molten metal matrix is ​​poured in, and then pressure infiltration is performed, and after the infiltration is completed, it is cooled to room temperature, and then demolded to obtain a composite material containing a core mold; The melting temperature of the metal matrix in step 4 is 100 to 250° C. above the melting point; The pressure applied during the pressure infiltration process in step 4 is 15 to 40 kN, and the pressure holding time is 3 to 10 minutes; 5. Core-removal treatment of composite materials containing core molds: The composite material containing the core mold obtained in step 4 is subjected to mechanical de-gypsum treatment, and then the composite material is placed in a gypsum dissolving agent, and ultrasonic waves are applied to remove the residual gypsum on the surface. Finally, the composite material is cleaned and dried.

2. The method for near-net-shape forming of high-precision and high-density complex metal-based composite materials by built-in core mold according to claim 1, characterized in that: The particle size of the reinforcing phase in step 1 is 50nm to 100μm.

3. The method for near-net-shape forming of high-precision and high-density complex metal-based composite materials by built-in core mold according to claim 1, characterized in that: In step 1, the volume of the reinforcement phase is 40-60% of the volume of the composite material.

4. The method for near-net-shape forming of high-precision and high-density complex metal-based composite materials by built-in core mold according to claim 1, characterized in that: Step 2: The complex metal matrix composite material component is a thin-walled structure or has one or more shapes including grooves, edges and corners, and curved surfaces.

5. The method for near-net-shape forming of high-precision and high-density complex metal-based composite components by built-in core mold according to claim 1, characterized in that: The mass ratio of water to gypsum powder in step 2 is (0.4-0.5):

1.

6. The method for near-net-shape forming of high-precision and high-density complex metal-based composite materials by built-in core mold according to claim 1, characterized in that: The drying pretreatment in step 2 is drying or multi-stage roasting; the drying process is: keeping warm at 150-250°C for 2-4h, and the heating rate is 2.5-5°C / min; the multi-stage roasting process is: keeping warm at 80-100°C for 7.5-8.5h, heating to 145-155°C for 3.5-4.5h, heating to 245-255°C for 1.5-2.5h, heating to 345-355°C for 1.5-2.5h, heating to 445-455°C for 1.5-2.5h, heating to 545-555°C for 0.5-1.5h, heating to 650-700°C for 1.5-2.5h, furnace cooling to 200-300°C for 2-3h, and the heating rate is 2.5-5°C / min.

7. The method for near-net-shape forming of high-precision and high-density complex metal matrix composite components by built-in core mold according to claim 1, characterized in that: The protective atmosphere in step 4 is a nitrogen atmosphere, an argon atmosphere or a helium atmosphere.

8. The method for near-net-shape forming of high-precision and high-density complex metal-based composite materials by built-in core mold according to claim 1, characterized in that: The preheating temperature in step 4 is 400-600° C. and the time is 2-3 hours.

9. The method for near-net-shape forming of high-precision and high-density complex metal-based composite components by built-in core mold according to claim 1, characterized in that: The cooling rate in step 4 is 20-40°C / h.

10. The method for near-net-shape forming of high-precision and high-density complex metal matrix composite components by built-in core mold according to claim 1, characterized in that: The mechanical plaster removal process described in step 5 is lathe processing or milling processing.

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