Preparation Device and Preparation Method of a High-Density Gradient Aluminum Matrix Composite

Abstract

The present invention discloses a preparation device and a preparation method for a highly dense gradient aluminum matrix composite material. Through this device, the sequential filling and mixing of aluminum alloy melt and aluminum matrix composite material melt can be realized. By means of the structure that the upper mold in the mold chamber can move up and down, the cavity size of the mold chamber is changed to ensure the fusion of the melt in the cavity of the mold chamber, and the temperature in the cavity of the mold chamber can be precisely controlled, so that the composite material melt can be better formed and solidified, realizing the control of the temperature field gradient during the filling of the aluminum matrix composite material, meeting the conditions for the preparation of gradient aluminum matrix composite material castings with complete filling and high density, ensuring that the top of the melt is always in contact with the insulation layer, enabling the melt to solidify gradually from the bottom upwards, avoiding shrinkage holes or porosity defects caused by premature solidification of the top of the melt, thereby controlling the temperature field gradient during the filling of the aluminum matrix composite material and ensuring the filling effect and quality of the melt.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum matrix composite material production, and specifically relates to a preparation device and a preparation method for a high-density gradient aluminum matrix composite material. Background Art

[0002] Particle-reinforced aluminum matrix composites have many advantages such as high specific strength, high specific stiffness, high wear resistance, and high damping capacity. The reinforcing particles can significantly improve the elastic modulus, yield strength, abrasion resistance, and high-temperature creep resistance of the matrix at a relatively low content, and thus have gradually attracted attention. At present, the toughness and strength synergy of homogeneous aluminum matrix composite castings is low, and traditional casting techniques for preparing aluminum matrix composite castings often have problems such as poor fluidity and incomplete filling during the casting process.

[0003] For example, an aluminum matrix composite casting, its casting method, and a casting device with a publication number of CN119387497A inject an aluminum matrix composite melt into the first chamber of a mold chamber through a riser pipe of a melting device, and divide the mold cavity into a first chamber and a second chamber by a sand core, and at least one runner connecting the first chamber and the second chamber is provided on the sand core; the runner is configured to cool the aluminum matrix composite melt to a semi-solid slurry, so as to realize the rapid filling of the slurry into the second chamber and rapid solidification, and an aluminum matrix composite casting with full filling, high density, fine working surface structure, and uniform distribution of reinforcing phases can be obtained. However, there are still problems such as poor fluidity of the composite melt resulting in incomplete forming, and the various properties of the aluminum matrix composite cannot be effectively improved, and there is still a large room for improvement in its density.

[0004] Therefore, there is an urgent need for a preparation device and a preparation method for a high-density gradient aluminum matrix composite material to ensure the successful preparation of an aluminum matrix composite material with high density and excellent properties. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation device and a preparation method for a high-density gradient aluminum matrix composite material to solve at least one of the problems and defects mentioned in the above background art.

[0006] Specifically, the first aspect of the present invention discloses a preparation device for a high-density gradient aluminum matrix composite material, including:

[0007] A furnace body, a mold chamber, and a vacuum pumping device. The mold chamber is provided with an upper mold and a lower mold, and the upper mold is movably arranged up and down in the mold chamber;

[0008] The vacuum pumping device is respectively connected to one side of the furnace body and the mold chamber;

[0009] The other side of the furnace body is provided with an inert gas delivery device;

[0010] A transmission assembly is provided at the bottom of the furnace body, and an aluminum alloy melt crucible and an aluminum matrix composite melt crucible are respectively arranged on the transmission assembly;

[0011] A lifting pipe is provided at the top of the furnace body. The top of the lifting pipe is communicated with the mold chamber, and the lifting pipe is communicably connected to the aluminum alloy melt crucible and the aluminum matrix composite melt crucible in a switchable manner;

[0012] A fourth transmission shaft is provided on the upper mold, and the bottom of the fourth transmission shaft is connected to the top of the upper mold.

[0013] The preparation device for the high-density gradient aluminum matrix composite material according to the present invention has at least the following beneficial effects:

[0014] In the present invention, a double induction melting furnace with an aluminum alloy melt crucible and an aluminum matrix composite melt crucible is arranged in the furnace body under a vacuum state, so as to realize the sequential filling and mixing of the aluminum alloy melt and the aluminum matrix composite melt. By means of the structure that the upper mold in the mold chamber can move up and down, the cavity size of the mold chamber is changed to ensure that the melt is fused in the cavity of the mold chamber, and the temperature in the cavity of the mold chamber can be accurately controlled, so that the composite melt can be better formed and solidified, realizing the control of the temperature field gradient during the filling of the aluminum matrix composite material and meeting the conditions for preparing a gradient aluminum matrix composite casting with complete filling and high density.

[0015] In the present invention, since the upper mold is movably arranged up and down in the mold chamber, it is ensured that the top of the melt is always in contact with the heat preservation layer, so that the melt solidifies gradually from the bottom upwards, and there is enough time for feeding during the solidification process, avoiding shrinkage holes or gas hole defects caused by premature solidification of the top of the melt; thereby controlling the temperature field gradient during the filling of the aluminum matrix composite material, ensuring the filling effect and quality of the melt, and finally obtaining a gradient aluminum matrix composite casting with high density and excellent performance.

[0016] As a further solution of the present invention: The vacuum pumping device is respectively provided with a first vacuum pipe, a second vacuum pipe and a third vacuum pipe. The first vacuum pipe is communicated with the furnace body, the second vacuum pipe is communicated with the mold chamber, the third vacuum pipe is communicated with the first vacuum pipe and the second vacuum pipe respectively. A first valve is arranged on the first vacuum pipe, a second valve is arranged on the second vacuum pipe, and a third valve is arranged on the third vacuum pipe.

[0017] The vacuum pumping device realizes independent vacuum control and linkage operation of the furnace body and the mold chamber by setting the first vacuum tube, the second vacuum tube, and the third vacuum tube and coordinating the control of the valves. It can perform vacuum pumping on the furnace body and the mold chamber separately or simultaneously, and can adjust the vacuum degrees of the furnace body and the mold chamber respectively to ensure precise control of the vacuum environment in different stages such as melting, filling, and solidification, optimizing the material preparation process. And by opening the third valve, the vacuum degrees of the furnace body and the mold chamber can be kept consistent to ensure the coordination of the entire preparation process. For example, during the filling process, the vacuum degrees of the furnace body and the mold chamber need to be kept consistent to avoid poor melt flow or the generation of bubbles, ensuring the uniformity and consistency of the vacuum degrees of the furnace body and the mold chamber.

[0018] As a further solution of the present invention: The transmission assembly includes a motor arranged outside the bottom of the furnace body. A hydraulic rod is arranged on the top of the motor, and a first transmission shaft is arranged on the top of the hydraulic rod.

[0019] As a further solution of the present invention: On both sides of the top of the first transmission shaft, a first transmission platform and a second transmission platform are respectively arranged. A second transmission shaft is arranged on the top of the first transmission platform, a third transmission shaft is arranged on the top of the second transmission platform. The aluminum alloy melt crucible is arranged on the second transmission shaft, and the aluminum matrix composite material melt crucible is arranged on the third transmission shaft.

[0020] Since the transmission assembly includes a motor arranged outside the bottom of the furnace body, a hydraulic rod is arranged on the top of the motor. The hydraulic rod penetrates through the bottom of the furnace body, and a first transmission shaft is arranged on the top of the hydraulic rod. On both sides of the top of the first transmission shaft, a first transmission platform and a second transmission platform are respectively arranged. A second transmission shaft is arranged on the top of the first transmission platform, a third transmission shaft is arranged on the top of the second transmission platform. The aluminum alloy melt crucible is arranged on the second transmission shaft, and the aluminum matrix composite material melt crucible is arranged on the third transmission shaft. By arranging a double induction melting furnace in the furnace body in a vacuum state, the transmission assembly can respectively rotate the aluminum alloy melt crucible and the aluminum matrix composite material melt crucible to below the riser pipe and lift and lower the crucibles. Lift the crucibles to insert the riser pipes into the crucibles, and use the inert gas conveying device to convey inert gas, so that under the action of the pressure difference, the alloy melts in the two crucibles are respectively filled into the cavity of the mold chamber in the furnace body and the mold chamber, realizing the sequential filling and mixing of the aluminum alloy melt and the aluminum matrix composite material melt, meeting the preparation of aluminum matrix composite material castings and ensuring its excellent performance.

[0021] As a further solution of the present invention: Resistance heating furnaces are evenly arranged on the outer walls of the aluminum alloy melt crucible and the aluminum matrix composite material melt crucible respectively.

[0022] Since resistance heating furnaces are evenly arranged on the outer walls of the crucibles for aluminum alloy melt and the crucibles for aluminum matrix composite melt respectively, the temperature of the crucibles can be ensured, the melt viscosity in the crucibles can be optimized, and its fluidity can be improved, enabling the melt to smoothly fill the cavity in the mold chamber through the riser tube, effectively reducing pores, shrinkage cavities and other defects in the casting, and improving the density and mechanical properties of the casting.

[0023] As a further solution of the present invention: a mechanical stirring device is arranged inside the crucible for aluminum matrix composite melt.

[0024] By arranging a mechanical stirring device inside the crucible for aluminum matrix composite melt, the reinforcing phase can be effectively and evenly dispersed in the aluminum matrix, avoiding the agglomeration or segregation of the reinforcing phase, ensuring the uniform distribution of the reinforcing phase in the composite material, thereby improving the overall performance of the material. And through mechanical stirring, the viscosity of the aluminum matrix composite melt can be reduced, its fluidity can be improved, defects such as pores and shrinkage cavities can be reduced, the full mixing of different components in the melt can be promoted, the homogeneity and consistency of the material can be improved, and the filling quality can be ensured to be improved.

[0025] As a further solution of the present invention: electromagnetic stirrers are respectively arranged on both sides of the riser tube.

[0026] Since electromagnetic stirrers are respectively arranged on both sides of the riser tube, during the filling process of the melt in the crucible through the riser tube, strong eddy current motion is generated inside the melt, significantly improving the fluidity of the melt, ensuring the uniform flow of the melt during the filling process, avoiding insufficient local filling or too fast filling, thereby improving the filling effect of the cavity in the mold chamber, reducing filling defects, and being able to effectively disperse the reinforcing phase, preventing its agglomeration or deposition at the bottom of the melt, ensuring the uniform distribution of the reinforcing phase in the aluminum matrix, reducing pores and inclusions in the casting, and improving the density and purity of the casting, ensuring the consistency, stability and efficiency of filling.

[0027] As a further solution of the present invention: the upper mold includes a heat insulation layer and a metal layer, and a plurality of exhaust grooves are arranged on the upper mold.

[0028] Since the upper mold includes a heat-insulating layer and a metal layer, and the upper mold is provided with a plurality of exhaust grooves, the top of the melt filling from the crucible into the cavity of the mold chamber contacts the heat-insulating layer, which can delay the cooling rate of the top of the melt, enable the melt to solidify gradually from the bottom upwards, and have sufficient time for feeding during the solidification process, avoiding shrinkage cavities or porosity defects caused by premature solidification of the top of the melt; and by adjusting the thickness of the heat-insulating layer to change the heat transfer coefficient, the adjustment of the cooling rate of 20 °C / min - 100 °C / min can be achieved, so as to control the temperature field gradient during the filling of the aluminum matrix composite material, ensure the filling effect and quality of the melt. At the same time, after the melt filling is completed, the upper mold can release the excess pressure in the mold chamber through the exhaust grooves, and the amount of inert gas in the furnace body can be controlled by the inert gas conveying device, so that the pressure difference between the furnace body and the mold chamber can be adjusted, which helps to improve the feeding effect in the final stage of the casting, reduce shrinkage cavities and porosity defects in the casting, and effectively improve the density of the casting.

[0029] As a further solution of the present invention: a baffle is provided on the upper part of the upper mold, and the fourth transmission shaft penetrates through the baffle and is connected to the top of the upper mold.

[0030] Since a baffle is provided on the upper part of the upper mold and the fourth transmission shaft penetrates through the baffle and is connected to the top of the upper mold, the fourth transmission shaft can drive the upper mold to move up and down in the mold chamber, thereby changing the cavity size of the mold chamber, and ensuring that the top of the melt always contacts the heat-insulating layer; when the aluminum alloy melt fills into the cavity of the mold chamber, the cavity space of the mold chamber is occupied. At this time, the aluminum alloy melt contacts the heat-insulating layer of the upper mold. In order to continue filling the aluminum matrix composite material melt into the cavity of the mold chamber, the upper mold is moved upwards at this time to increase the cavity of the mold chamber. After the aluminum matrix composite material melt fills into the cavity of the mold chamber, the top of the mixed melt of the aluminum alloy melt and the aluminum matrix composite material melt contacts the heat-insulating layer, ensuring that the cooling rate of the top of the melt can be delayed and the final casting can be obtained.

[0031] When a casting needs to be filled, the furnace body and the mold chamber are evacuated to a vacuum state by a vacuum pumping device. The motor is started, and the first transmission shaft drives the first transmission platform and the second transmission platform to rotate simultaneously, so that one of the crucibles for aluminum alloy melt or the crucible for aluminum matrix composite melt rotates to the lower part of the riser tube. At this time, the second transmission shaft or the third transmission shaft starts to lift, raising the corresponding crucible for aluminum alloy melt or the crucible for aluminum matrix composite melt. The riser tube is inserted into the lifted crucible. At the same time, the inert gas delivery device and the electromagnetic stirrer are turned on. Under the pressure difference between the furnace body and the mold chamber, the alloy melt in the crucible is filled into the cavity of the mold chamber, and the top of the melt is brought into contact with the insulation layer of the upper mold to keep the melt warm. After the alloy melt in one crucible is filled into the cavity of the mold chamber, the lifted crucible is lowered, and the vacuum is pumped again. Then, the first transmission shaft drives the first transmission platform and the second transmission platform to rotate simultaneously, rotating the other crucible to the lower part of the riser tube, repeating the above actions, and raising the upper mold to increase the cavity of the mold chamber, filling the alloy melt in the other crucible into the cavity of the mold chamber. During the filling process of the aluminum matrix composite melt, the mechanical stirring device is turned on, and the aluminum matrix composite melt continues to be filled into the cavity of the mold chamber under the stirring action. Finally, the pressure difference between the furnace body and the mold chamber is adjusted by the inert gas delivery device, and pressure is continuously applied to the casting after filling until the casting is completely solidified, and then the mold is opened to take out the casting.

[0032] The second aspect of the present invention also discloses a preparation method of a preparation device for a high-density gradient aluminum matrix composite material, including the following steps:

[0033] S1. Evacuate the furnace body and the mold chamber to a vacuum state;

[0034] S2. Heat up the aluminum alloy melt in the crucible for aluminum alloy melt and the aluminum matrix composite melt in the crucible for aluminum matrix composite melt, and at the same time heat up the mold chamber;

[0035] S3. Raise the crucible for aluminum alloy melt, insert the riser tube into the aluminum alloy melt, turn on the inert gas delivery device, and the aluminum alloy melt is drawn into the mold chamber, and then lower the crucible for aluminum alloy melt to its original position;

[0036] S4. Evacuate the furnace body and the mold chamber to a vacuum state again, raise the crucible for aluminum matrix composite melt, insert the riser tube into the aluminum matrix composite melt, and at the same time raise the insulation layer and the metal layer of the upper mold to obtain a casting;

[0037] S5. The aluminum matrix composite melt continues to be filled under the action of electromagnetic stirring. After filling is completed, pressure is increased until the casting is completely solidified, and then the mold is opened to take out the casting.

[0038] Through this preparation method, the aluminum alloy melt and the aluminum matrix composite melt can be effectively and uniformly mixed during the filling process, optimizing the mixing and filling process of the melt, improving the density and surface quality of the casting; and reducing shrinkage cavities and porosity defects in the casting, enabling the casting to form the required gradient structure, meeting the requirements of high-performance aluminum matrix composites, effectively improving the casting of complex structures with thin walls, and without complex processes, making the production cost controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] For the convenience of those skilled in the art to understand, the present invention will be further described below with reference to the accompanying drawings.

[0040] Figure 1 It is a schematic structural diagram of a preparation device for a high-density gradient aluminum matrix composite;

[0041] Figure 2 It is a schematic diagram of the microstructure of a gradient composite prepared by a preparation device for a high-density gradient aluminum matrix composite;

[0042] Figure 3 It is an element mapping diagram of a product prepared by a preparation device for a high-density gradient aluminum matrix composite;

[0043] Figure 4 It is a schematic diagram of an industrial CT of a product prepared by a preparation device for a high-density gradient aluminum matrix composite;

[0044] Figure 5 For Figure 3 the XY-direction CT schematic diagram;

[0045] Figure 6 For Figure 3 the XZ-direction CT schematic diagram;

[0046] Figure 7 For Figure 3 the YZ-direction CT schematic diagram.

[0047] Reference Signs:

[0048] 1. Furnace body; 2. Mold chamber; 21. Upper mold; 211. Thermal insulation layer; 212. Metal layer; 213. Exhaust groove; 22. Lower mold; 3. Vacuum pumping device; 31. First vacuum tube; 311. First valve; 32. Second vacuum tube; 321. Second valve; 33. Third vacuum tube; 331. Third valve; 4. Inert gas delivery device; 5. Transmission assembly; 51. Motor; 52. Hydraulic rod; 53. First transmission shaft; 54. First transmission platform; 55. Second transmission platform; 56. Second transmission shaft; 57. Third transmission shaft; 6. Aluminum alloy melt crucible; 7. Aluminum matrix composite melt crucible; 8. Lifting pipe; 9. Resistance heating furnace; 10. Mechanical stirring device; 11. Electromagnetic stirrer; 12. Baffle; 13. Fourth transmission shaft. Detailed implementation manners

[0049] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the technical solutions of the present invention will be further specifically described below through embodiments in combination with the accompanying drawings. In the specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation to the present invention.

[0050] In addition, in the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the disclosed embodiments. However, it is obvious that one or more embodiments can be implemented without these specific details. In other cases, well-known structures and devices are illustrated in a schematic manner to simplify the drawings.

[0051] As Figure 1 shown in the embodiments of the present invention, a device for preparing a high-density gradient aluminum matrix composite material includes: a furnace body 1, a mold chamber 2, and a vacuum pumping device 3. The mold chamber 2 is provided with an upper mold 21 and a lower mold 22. The upper mold 21 is movably arranged up and down in the mold chamber 2; the vacuum pumping device 3 is respectively communicated with one side of the furnace body 1 and the mold chamber 2; the other side of the furnace body 1 is provided with an inert gas delivery device 4; the bottom of the furnace body 1 is provided with a transmission assembly 5, and an aluminum alloy melt crucible 6 and an aluminum matrix composite melt crucible 7 are respectively arranged on the transmission assembly 5; the top of the furnace body 1 is provided with a lifting pipe 8, the top of the lifting pipe 8 is communicated with the mold chamber 2, and the lifting pipe 8 is selectively communicated with the aluminum alloy melt crucible 6 and the aluminum matrix composite melt crucible 7; the upper mold 21 is provided with a fourth transmission shaft 13, and the bottom of the fourth transmission shaft 13 is connected to the top of the upper mold 21.

[0052] Specifically, the present invention realizes the sequential filling and mixing of the aluminum alloy melt and the aluminum matrix composite melt by setting a double induction melting furnace with an aluminum alloy melt crucible and an aluminum matrix composite melt crucible in a furnace body under a vacuum state. Through the structure that the upper mold in the mold chamber can move up and down, the size of the cavity in the mold chamber is changed to ensure the fusion of the melt in the cavity of the mold chamber, and the temperature in the cavity of the mold chamber can be precisely controlled, enabling the composite melt to better form and solidify, realizing the control of the temperature field gradient during the filling of the aluminum matrix composite, and meeting the conditions for preparing a gradient aluminum matrix composite casting with complete filling and high density.

[0053] Due to the setting that the upper mold can move up and down in the mold chamber in the present invention, it is ensured that the top of the melt is always in contact with the heat preservation layer, enabling the melt to solidify gradually from the bottom upwards, and having sufficient time for feeding during the solidification process, avoiding shrinkage cavity or porosity defects caused by premature solidification of the top of the melt; thereby controlling the temperature field gradient during the filling of the aluminum matrix composite, ensuring the filling effect and quality of the melt, and finally obtaining a gradient aluminum matrix composite casting with high density and excellent performance.

[0054] As Figure 1 shown, the vacuum pumping device 3 is respectively provided with a first vacuum tube 31, a second vacuum tube 32 and a third vacuum tube 33. The first vacuum tube 31 is connected to the furnace body 1, the second vacuum tube 32 is connected to the mold chamber 2, the third vacuum tube 33 is connected to the first vacuum tube 31 and the second vacuum tube 32 respectively. The first vacuum tube 31 is provided with a first valve 311, the second vacuum tube 32 is provided with a second valve 321, and the third vacuum tube 33 is provided with a third valve 331.

[0055] Specifically, by setting the first vacuum tube 31, the second vacuum tube 32 and the third vacuum tube 33 and cooperating with the control of the valves, the vacuum pumping device 3 realizes the independent vacuum control and linkage operation of the furnace body 1 and the mold chamber 2, can perform vacuum pumping treatment on the furnace body 1 and the mold chamber 2 separately or simultaneously, can respectively adjust the vacuum degrees of the furnace body 1 and the mold chamber 2, ensures that the vacuum environment can be precisely controlled in different stages such as melting, filling and solidification, and optimizes the material preparation process; and by opening the third valve 331, the vacuum degrees of the furnace body 1 and the mold chamber 2 can be kept consistent, ensuring the coordination of the entire preparation process. For example, during the filling process, the vacuum degrees of the furnace body 1 and the mold chamber 2 need to be kept consistent to avoid poor melt flow or generation of bubbles, and ensure the uniformity and consistency of the vacuum degrees of the furnace body 1 and the mold chamber 2.

[0056] According to an embodiment of the present invention, as Figure 1As shown in the figure, the transmission assembly 5 includes a motor 51 disposed outside the bottom of the furnace body 1. A hydraulic rod 52 is provided on the top of the motor 51. The hydraulic rod 52 penetrates through the bottom of the furnace body 1, and a first transmission shaft 53 is provided on the top of the hydraulic rod 52. On both sides of the top of the first transmission shaft 53, a first transmission platform 54 and a second transmission platform 55 are respectively provided. A second transmission shaft 56 is provided on the top of the first transmission platform 54, and a third transmission shaft 57 is provided on the top of the second transmission platform 55. The aluminum alloy melt crucible 6 is disposed on the second transmission shaft 56, and the aluminum matrix composite melt crucible 7 is disposed on the third transmission shaft 57.

[0057] Specifically, since the transmission assembly 5 includes a motor 51 disposed outside the bottom of the furnace body 1. A hydraulic rod 52 is provided on the top of the motor 51. The hydraulic rod 52 penetrates through the bottom of the furnace body 1, and a first transmission shaft 53 is provided on the top of the hydraulic rod 52. On both sides of the top of the first transmission shaft 53, a first transmission platform 54 and a second transmission platform 55 are respectively provided. A second transmission shaft 56 is provided on the top of the first transmission platform 54, and a third transmission shaft 57 is provided on the top of the second transmission platform 55. The aluminum alloy melt crucible 6 is disposed on the second transmission shaft 56, and the aluminum matrix composite melt crucible 7 is disposed on the third transmission shaft 57. By arranging a double induction melting furnace in the furnace body 1 in a vacuum state, the transmission assembly 5 can respectively rotate the aluminum alloy melt crucible 6 and the aluminum matrix composite melt crucible 7 to below the riser tube 8, and lift and lower the crucibles. Lift the crucibles to insert the riser tube 8 into the crucibles. Use the inert gas conveying device to convey inert gas, so that under the action of the pressure difference, the furnace body 1 and the mold chamber 2 respectively fill the alloy melts in the two crucibles into the cavity of the mold chamber 2, and the sequential filling and mixing of the aluminum alloy melt and the aluminum matrix composite melt can be realized, meeting the preparation of aluminum matrix composite castings and ensuring its excellent performance.

[0058] As Figure 1 shown, resistance heating furnaces 9 are uniformly arranged on the outer walls of the aluminum alloy melt crucible 6 and the aluminum matrix composite melt crucible 7 respectively.

[0059] Specifically, since resistance heating furnaces 9 are uniformly arranged on the outer walls of the aluminum alloy melt crucible 6 and the aluminum matrix composite melt crucible 7 respectively, the temperature of the crucibles can be ensured, the melt viscosity in the crucibles can be optimized, and its fluidity can be improved, so that the melt can smoothly fill the cavity of the mold chamber 2 through the riser tube 8, effectively reducing pores, shrinkage cavities and other defects in the castings and improving the density and mechanical properties of the castings.

[0060] According to an embodiment of the present invention, as Figure 1 shown, a mechanical stirring device 10 is provided in the aluminum matrix composite melt crucible 7.

[0061] Specifically, by arranging a mechanical stirring device 10 inside the crucible 7 of the aluminum matrix composite melt, the reinforcing phase can be effectively and evenly dispersed in the aluminum matrix, avoiding the agglomeration or segregation of the reinforcing phase, ensuring the uniform distribution of the reinforcing phase in the composite material, thereby improving the overall performance of the material. Moreover, through mechanical stirring, the viscosity of the aluminum matrix composite melt can be reduced, its fluidity can be improved, defects such as gas holes and shrinkage cavities can be reduced, the full mixing of different components in the melt can be promoted, the uniformity and consistency of the material can be improved, and the filling quality can be ensured to be improved.

[0062] Furthermore, electromagnetic stirrers 11 are respectively arranged on both sides of the riser tube 8.

[0063] Specifically, since electromagnetic stirrers 11 are respectively arranged on both sides of the riser tube, during the filling process of the melt in the crucible through the riser tube 8, strong vortex motion is generated inside the melt, significantly improving the fluidity of the melt, ensuring the uniform flow of the melt during the filling process, avoiding local underfilling or overfilling, thereby improving the filling effect of the cavity 2 of the mold chamber, reducing filling defects, and being able to effectively disperse the reinforcing phase, preventing its agglomeration or deposition at the bottom of the melt, ensuring the uniform distribution of the reinforcing phase in the aluminum matrix, reducing gas holes and inclusions in the casting, and improving the density and purity of the casting, ensuring the consistency, stability, and efficiency of filling.

[0064] According to an embodiment of the present invention, as Figure 1 shown, the upper mold 21 includes a heat insulation layer 211 and a metal layer 212, and the upper mold 21 is provided with a plurality of exhaust grooves 213.

[0065] Specifically, since the upper mold 21 includes a heat insulation layer 211 and a metal layer 212, and the upper mold 21 is provided with a plurality of exhaust grooves 213, the top of the melt filled from the crucible into the cavity of the mold chamber 2 contacts the heat insulation layer 211, which can delay the cooling rate of the top of the melt, enable the melt to solidify gradually from the bottom upwards, and have sufficient time for feeding during the solidification process, avoiding shrinkage cavity or gas hole defects caused by premature solidification of the top of the melt; and by adjusting the thickness of the heat insulation layer 211 to change the heat transfer coefficient, the adjustment of the cooling rate of 20°C / min - 100°C / min can be realized, thereby controlling the temperature field gradient during the filling of the aluminum matrix composite, ensuring the filling effect and quality of the melt. At the same time, after the filling of the melt is completed, the upper mold 21 can release the excess pressure in the mold chamber 2 through the exhaust grooves 213, and the amount of inert gas in the furnace body 1 is controlled by the inert gas conveying device 4 in the furnace body 1, so that the pressure difference between the furnace body 1 and the mold chamber 2 can be adjusted, which helps to improve the feeding effect in the last stage of the casting, reduce shrinkage cavity and porosity defects in the casting, and effectively improve the density of the casting.

[0066] Furthermore, a baffle 12 is arranged at the upper part of the upper mold 21, and the fourth transmission shaft 13 passes through the baffle and is connected to the top of the upper mold 21.

[0067] Specifically, since a baffle 12 is provided on the upper part of the upper die 21, and the fourth transmission shaft 13 passes through the baffle and is connected to the top of the upper die 21, the fourth transmission shaft 13 can drive the upper die 21 to move up and down in the die chamber 2, thereby changing the cavity size of the die chamber 2, ensuring that the top of the melt is always in contact with the heat preservation layer 211; when the aluminum alloy melt fills the cavity of the die chamber 2, the cavity space of the die chamber 2 is occupied, and at this time the aluminum alloy melt is in contact with the heat preservation layer 211 of the upper die 21. In order to continue filling the aluminum matrix composite melt into the cavity of the die chamber 2, at this time, by moving the upper die 21 upward, the cavity of the die chamber 2 is increased. When the aluminum matrix composite melt fills into the cavity of the die chamber 2, the top of the mixed melt of the aluminum alloy melt and the aluminum matrix composite melt is in contact with the heat preservation layer 211, ensuring that the cooling rate of the top of the melt can be delayed and the final casting can be obtained.

[0068] When casting a casting is required, the furnace body 1 and the die chamber 2 are evacuated to a vacuum state by the vacuum pumping device 3, the motor 51 is started, and the first transmission shaft 53 drives the first transmission platform 54 and the second transmission platform 55 to rotate simultaneously, so that one of the aluminum alloy melt crucible 6 or the aluminum matrix composite melt crucible 7 rotates to below the riser tube 8. At this time, the second transmission shaft 56 or the third transmission shaft 57 starts to lift, raising the corresponding aluminum alloy melt crucible 6 or the aluminum matrix composite melt crucible 7, inserting the riser tube 8 into the lifted crucible. At the same time, the inert gas delivery device 4 and the electromagnetic stirrer 11 are turned on. Under the pressure difference between the furnace body 1 and the die chamber 2, the alloy melt in the crucible is filled into the cavity of the die chamber 2, and the top of the alloy melt is in contact with the heat preservation layer 211 of the upper die 21 to keep the melt warm; after the alloy melt in one crucible is filled into the cavity of the die chamber 2, the lifted crucible is lowered and evacuated again. Then, the first transmission shaft 53 drives the first transmission platform 54 and the second transmission platform 55 to rotate simultaneously, rotating the other crucible to below the riser tube 8, repeating the above actions, and raising the upper die 21 to increase the cavity of the die chamber 2, filling the alloy melt in the other crucible into the cavity of the die chamber 2; during the filling process of the aluminum matrix composite melt, the mechanical stirring device 10 is turned on, and the aluminum matrix composite melt continues to be filled into the cavity of the die chamber 2 under the stirring action; finally, the pressure difference between the furnace body 1 and the die chamber 2 is adjusted by the inert gas delivery device 4, and pressure is continuously applied to the casting after filling until the casting is completely solidified, and then the mold is opened to take out the part.

[0069] The second aspect of the present invention also discloses a preparation method of a preparation device for a high-density gradient aluminum matrix composite material, including the following steps:

[0070] S1. Evacuate the furnace body 1 and the die chamber 2 to a vacuum state;

[0071] S2. Heat up the aluminum alloy melt in the crucible 6 of the aluminum alloy melt and the aluminum matrix composite melt in the crucible 7 of the aluminum matrix composite melt, and at the same time heat up the mold chamber 2.

[0072] S3. Raise the crucible 6 of the aluminum alloy melt, insert the lift pipe 8 into the aluminum alloy melt, turn on the inert gas delivery device 4, and the aluminum alloy melt is drawn into the mold chamber 2, then lower the crucible 6 of the aluminum alloy melt to its original position.

[0073] S4. Evacuate the furnace body 1 and the mold chamber 2 to a vacuum state again, raise the crucible 7 of the aluminum matrix composite melt, insert the lift pipe 8 into the aluminum matrix composite melt, and at the same time, raise the insulation layer 211 and the metal layer 212 of the upper mold 21 to obtain a casting.

[0074] S5. The aluminum matrix composite melt continues to fill the mold under the action of electromagnetic stirring. After the filling is completed, increase the pressure until the casting is completely solidified, and then open the mold to take out the part.

[0075] As Figure 2 and 3 shown, the present invention realizes the near-net forming of gradient materials and can achieve the metallurgical bonding of the aluminum alloy layer and the aluminum matrix composite layer under a vacuum environment throughout the process. Compared with the preparation of existing aluminum matrix composites, the present invention avoids the oxide layer that may exist in the laminated bonding area and significantly improves the thermodynamic properties of the laminated area of the gradient composite material;

[0076] The present invention realizes the filling of the composite melt while stirring under the action of electromagnetic stirring, further improving the uniform distribution of the reinforcing phase in the aluminum matrix composite material.

[0077] As Figures 4 - 7 shown, it can be seen from the sectional view and the three-dimensional gray-scale image that the maximum resolution of the sample is 81 μm. Through analysis, it is found that there are no pores in the image, which indicates that there are no pores with a size of 81 μm and above at the maximum resolution of X-CT, and the sample is very dense, reaching more than 99.96%.

[0078] The present invention innovates on the basis of the vacuum electromagnetic stirring suction casting technology, and ingeniously designs a special mold for gradient composite materials suitable for the suction casting device. Through the hydraulic pressure of the mold structure and the differential pressure at the lift pipe of the suction casting to apply two-way pressure, the gradient casting is solidified and compensated under a double high-pressure environment, and a high-density aluminum matrix composite casting is obtained.

[0079] Specifically, through this preparation method, the aluminum alloy melt and the aluminum matrix composite melt can be effectively and uniformly mixed during the filling process, optimizing the mixing and filling process of the melt, improving the density and surface quality of the casting; and reducing the shrinkage cavity and porosity defects in the casting, enabling the casting to form the required gradient structure, meeting the requirements of high-performance aluminum matrix composites, effectively improving the casting of complex structures with thin walls, and without complex processes, making the production cost controllable.

[0080] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-density gradient aluminum-based composite material, the method being carried out in a device for preparing a high-density gradient aluminum-based composite material, characterized in that: The preparation device comprises: A furnace body, a mold chamber and a vacuum device, wherein the mold chamber is provided with an upper mold and a lower mold, and the upper mold is movable upward and downward and is arranged in the mold chamber; The vacuum extraction device is communicated with the furnace body and one side of the mold chamber respectively; An inert gas conveying device is provided on the other side of the furnace body; A transmission assembly is provided at the bottom of the furnace body, and an aluminum alloy melt crucible and an aluminum-based composite material melt crucible are respectively provided on the transmission assembly; A liquid riser is provided on the top of the furnace body, the top of the liquid riser is connected to the mold chamber, and the liquid riser is switchably connected to the aluminum alloy melt crucible and the aluminum-based composite material melt crucible; The upper mold is provided with a fourth transmission shaft, and the bottom of the fourth transmission shaft is connected to the top of the upper mold; The preparation method comprises the following steps: S1, evacuating the furnace body and the mold chamber to a vacuum state; S2, heating the aluminum alloy melt in the aluminum alloy melt crucible and the aluminum-based composite material melt in the aluminum-based composite material melt crucible, and heating the mold chamber at the same time; S3, raising the aluminum alloy melt crucible, inserting the liquid riser into the aluminum alloy melt, turning on the inert gas delivery device, drawing the aluminum alloy melt into the mold chamber, and lowering the aluminum alloy melt crucible to its original position; S4, evacuating the furnace body and the mold chamber to a vacuum state again, raising the aluminum-based composite material melt crucible, inserting the liquid riser into the aluminum-based composite material melt, and at the same time, raising the insulation layer and the metal layer of the upper mold to obtain a casting; S5. The aluminum-based composite material melt is continuously filled into the mold under the action of electromagnetic stirring. After the filling is completed, the pressure is increased until the casting is completely solidified, and the mold is opened to take out the part.

2. The method for preparing a high-density gradient aluminum-based composite material according to claim 1, characterized in that: The vacuum pumping device is respectively provided with a first vacuum tube, a second vacuum tube and a third vacuum tube, the first vacuum tube is connected to the furnace body, the second vacuum tube is connected to the mold chamber, the third vacuum tube is respectively connected to the first vacuum tube and the second vacuum tube, the first vacuum tube is provided with a first valve, the second vacuum tube is provided with a second valve, and the third vacuum tube is provided with a third valve.

3. The method for preparing a high-density gradient aluminum-based composite material according to claim 1, characterized in that: The transmission assembly comprises a motor arranged outside the bottom of the furnace body, a hydraulic rod is arranged on the top of the motor, the hydraulic rod penetrates the bottom of the furnace body, and a first transmission shaft is arranged on the top of the hydraulic rod.

4. The method for preparing a high-density gradient aluminum-based composite material according to claim 3, characterized in that: A first transmission platform and a second transmission platform are respectively arranged on both sides of the top of the first transmission shaft, a second transmission shaft is arranged on the top of the first transmission platform, a third transmission shaft is arranged on the top of the second transmission platform, the aluminum alloy melt crucible is arranged on the second transmission shaft, and the aluminum-based composite material melt crucible is arranged on the third transmission shaft.

5. The method for preparing a high-density gradient aluminum-based composite material according to claim 1, characterized in that: The outer walls of the aluminum alloy melt crucible and the aluminum-based composite material melt crucible are respectively and evenly provided with resistance heating furnaces.

6. The method for preparing a high-density gradient aluminum-based composite material according to claim 1, characterized in that: A mechanical stirring device is arranged in the aluminum-based composite material melt crucible.

7. The method for preparing a high-density gradient aluminum-based composite material according to claim 6, characterized in that: Electromagnetic stirrers are respectively arranged on both sides of the riser tube.

8. The method for preparing a high-density gradient aluminum-based composite material according to claim 1, characterized in that: The upper mold comprises a heat-insulating layer and a metal layer, and the upper mold is provided with a plurality of exhaust grooves.

9. The method for preparing a high-density gradient aluminum-based composite material according to claim 8, characterized in that: A baffle is arranged on the upper part of the upper die, a fourth transmission shaft is arranged through the baffle, and a bottom of the fourth transmission shaft is connected to the top of the upper die.

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