A bottom casting device and method for preparing particle-reinforced aluminum-based composite material

Abstract

The present invention relates to a bottom casting device and method for preparing particle-reinforced aluminum-based composite materials. The bottom casting device for preparing particle-reinforced aluminum-based composite materials comprises a casting port, a casting head is replaceably mounted with the casting port, and the casting head comprises a mounting section and a crushing section; an impact device for crushing the crushing section is arranged in the furnace body; a movable platform is arranged at the bottom of the furnace body, and a mold and a waste slag trough are arranged on the movable platform; the waste slag trough is used to receive the crushed crushing section and the rear part of the melt containing slag, and the mold is used to receive the front part of the uniform melt flowing out of the casting head; a cooling system is arranged at the corresponding position of the movable platform and the bottom of the mold. The corresponding bottom casting method comprises pretreatment, melting, addition of reinforcing phase particles, particle homogenization of the composite material melt, bottom casting, and subsequent heat treatment. The combination of the above-mentioned device and method improves the casting performance of the composite material and improves the production efficiency.

Description

Technical Field

[0001] The invention relates to the preparation of aluminum-based composite materials, and in particular to a bottom casting device and method for preparing particle-reinforced aluminum-based composite materials. Background Art

[0002] Aluminum-based composite materials have become a hot topic in recent years due to their excellent properties such as high specific strength, specific stiffness, wear resistance, low thermal expansion coefficient, good thermal conductivity and dimensional stability. Among them, particle-reinforced aluminum-based composite materials represented by SiC enable low-cost aluminum-based composite materials to achieve performance optimization through particle content and size, and have continuously achieved breakthroughs in aerospace, electronic packaging, automobile manufacturing and high-speed trains.

[0003] The main processes for preparing aluminum-based composite materials at present include stirring casting, powder metallurgy and pressure infiltration. Among them, the stirring casting method is to melt the base metal, form a vortex through mechanical or electromagnetic stirring, and at the same time, the added reinforcement phase particles are drawn into the molten metal under the action of the vortex to obtain a uniformly distributed melt, and cast under certain conditions to obtain a composite material. Compared with powder metallurgy and pressure infiltration, this method requires simple equipment and processes, has high production efficiency, low cost, and can mass-produce components with complex shapes. It is one of the most promising processes for achieving industrial large-scale production.

[0004] The casting processes used in stirring casting in the prior art include gravity casting, and anti-gravity casting methods such as suction casting and differential pressure casting. At present, the composite materials prepared by anti-gravity casting have better performance. However, the anti-gravity casting method has high requirements on equipment, high cost, and low production efficiency, which is not conducive to large-scale industrial production. Therefore, there is a need for a gravity casting device and method that can improve the casting performance of composite materials and improve production efficiency. Summary of the invention

[0005] The first technical problem to be solved by the present invention is to provide a bottom casting device for preparing particle-reinforced aluminum-based composite materials, which can improve the casting performance of composite materials and improve production efficiency in view of the current status of the prior art.

[0006] The second technical problem to be solved by the present invention is to provide a bottom casting method for preparing particle-reinforced aluminum-based composite materials using the aforementioned device to improve the wettability of the reinforcing phase with the aluminum melt, as well as the dispersion uniformity of the reinforcing phase particles in the aluminum melt, improve the casting performance of the composite material, and improve production efficiency, in response to the current status of the prior art.

[0007] The technical solution adopted by the present invention to solve the above technical problems is as follows: the bottom casting device for preparing particle-reinforced aluminum-based composite materials comprises a furnace body, a smelting container is arranged in the furnace body, and the bottom of the smelting container is a casting port with a melt flow channel; a secondary feeding device, a heating temperature control device, and a stirring device are provided in conjunction with the smelting container; a casting head is replaceably installed with the casting port, and the casting head includes a mounting section for cooperating with the melt flow channel, and a fragile fragmentation section; an impact device for breaking the fragmentation section is provided in the furnace body; a movable platform is provided at the bottom of the furnace body, and a mold and a waste slag trough are provided on the movable platform; when the movable platform is in the first position, the waste slag trough is used to receive the broken fragmentation section, and the mold is used to receive the front part of the uniform melt flowing out of the casting head, and when the movable platform is in the second position, the waste slag trough is used to receive the rear part of the melt containing slag; a cooling system is provided at the position corresponding to the bottom of the movable platform and the mold.

[0008] For better heat preservation, it is preferred that the smelting container is a graphite crucible.

[0009] In order to facilitate the replacement and removal of the casting head, the installation section of the casting head is an external thread section, so as to be matched and connected with the internal thread corresponding to the melt flow channel. With this type of casting head, a new casting head can be replaced before each casting.

[0010] In order to ensure the sealing property during smelting and prevent the melt from being blocked when flowing out, it is preferred that the ratio of the casting opening diameter of the casting head to the diameter of the smelting container is 1:5 to 1:15.

[0011] The installation section and the fragmentation section of the casting head can be made of different materials or the same material. In order to reduce the cost, the casting head is made of graphite, and the wall thickness of the installation section is greater than the wall thickness of the fragmentation section. The cost of mass production of the casting head using this material is very low, and the different functions of the installation section and the fragmentation section are realized by different wall thicknesses, with a simple structure and good effect.

[0012] For ease of operation, preferably, the impact device includes an impact head and a cylinder connected to the impact head.

[0013] In order to facilitate the adjustment of the cooling speed, the cooling system includes a cooling plate located on the movable platform, a water cooling channel is provided in the cooling plate, and a flow valve for adjusting the flow is provided at the water inlet of the water cooling channel. The cooling water flow can be adjusted by the flow valve so that the water temperature at the water outlet is 35-50°C.

[0014] In order to simplify the structure and facilitate operation, preferably, the movable platform includes a base plate and a slide rail on which the base plate is mounted.

[0015] In order to prevent the melt from being blocked at the outlet, the induction heating wire of the heating and temperature control device wraps the outer peripheral surface of the smelting container body and the outer peripheral surface at the casting port.

[0016] In order to improve the wettability of the reinforcing phase particles and facilitate the control of the feeding speed, the secondary feeding device preferably includes a secondary hopper, a screw feeder arranged in conjunction with the secondary hopper, and a resistance heating temperature control device arranged in conjunction with the secondary hopper.

[0017] Preferably, the stirring device includes a stirring rod located in the middle of the smelting container, and a motor for driving the stirring rod. The stirring rod is provided with a plurality of blade layers, including a spiral blade layer and a prismatic blade layer. The prismatic blade layer includes a plurality of prismatic blades arranged along the circumference of the stirring rod, and the cross-sectional polygon of the prismatic blade has at least one internal angle in the range of 30-60°.

[0018] The paddle layer of the stirring device structure includes a spiral paddle layer and a prismatic paddle layer. The spiral paddle layer can increase the downward pressure flow of the melt, which is helpful for the addition of the reinforcing phase and promotes the dispersion of the reinforcing phase; the prismatic paddle layer further gives the composite melt a lateral shear force, which is helpful for the crushing of the reinforcing phase agglomerated particles, greatly improving the dispersion uniformity of the reinforcing phase particles, and can also save the time required for the dispersion of the reinforcing phase particles. A cutting angle will be formed at the edge of the prismatic paddle layer, thereby producing a good shearing effect on the composite melt, having a good crushing effect on the reinforcing phase agglomerated particles, and the cutting effect formed by the inner angle range of 30-60° is better.

[0019] A bottom casting method for preparing a particle-reinforced aluminum-based composite material comprises the following steps:

[0020] (1) After pretreatment, the reinforcing phase particles are placed in a secondary feeding device for preheating;

[0021] (2) Preparation and smelting of aluminum-based alloy: put the ingredients into the smelting container according to the required aluminum alloy ratio, evacuate the container, introduce protective gas, and turn on the heating and temperature control device to completely melt the ingredients;

[0022] (3) Addition of reinforcing phase particles:

[0023] Turn on the stirring device (4), and when the temperature reaches the semi-solid range of 5-50°C below the liquidus, use the secondary feeding device (3) to add the reinforcing phase particles;

[0024] (4) Particle homogenization of composite melt:

[0025] After the reinforcing phase particles are added, the temperature is controlled in the range of 0-40°C below the liquidus line and stirred until uniform;

[0026] (5) Bottom casting:

[0027] To ensure the uniform distribution of the reinforcing phase in the melt during the casting process, after heating to the casting temperature, maintain a stirring speed of 300-1500r / min, preferably maintain a stirring speed of 600-900r / min to start bottom casting. Use an impact device to break up the fragmentation segment, and the fragments of the fragmentation segment fall into the slag trough. The mold receives the front part of the uniform melt flowing out of the casting port. At the same time, turn on the cooling system to cool the mold, and adjust the cooling water flow rate through the flow valve to make the water temperature range of the water outlet 35-50°C. Observe the degree of drop in the melt level through the observation window, and when the viscosity of the melt flowing out of the casting port increases, it means that the front part of the uniform melt has flowed out more fully. Move the movable platform so that the slag trough is placed at the casting port to receive the rear part of the melt containing slag;

[0028] (6) Subsequent heat treatment.

[0029] Preferably, the pretreatment in step (1) comprises the following steps: acid-washing the reinforcement phase particles and then washing them with water until they are neutral, then drying them at a temperature of 100-200° C., and then sieving them to obtain the reinforcement phase particles. This pretreatment process does not require high-temperature oxidation of the reinforcement phase particles in the prior art, thus saving energy consumption and shortening the production cycle.

[0030] Preferably, the preheating temperature in step (1) is 200-1000° C. to improve the wettability between the reinforcement phase and the melt.

[0031] In order to better promote the mixing of the reinforcing phase particles, preferably, the step (3) includes the following steps:

[0032] The first stage of stirring: In order to make the aluminum liquid composition uniform and remove the gas in the melt, turn on the stirring device and stir at a low speed of less than 300r / min

[0033] The second stage of stirring: When the temperature drops to the semi-solid range of 0-40℃ below the liquidus line, the stirring speed is increased to 300-1000r / min, so that a stirring vortex is formed on the surface of the melt to facilitate the subsequent addition of reinforcement phase particles into the melt; after a stable vortex is formed, a secondary feeding device is used to add reinforcement phase particles to the center of the vortex.

[0034] In order to make the reinforcement phase particles dispersed uniformly, preferably, the step (4) includes the following steps:

[0035] Semi-solid strong shear stirring: After the reinforcement phase particles are added, the temperature is controlled in the range of 0-40°C below the liquidus line, and the stirring speed is further increased to 400-2000r / min, preferably 800-1000r / min, and high-speed strong shear stirring is performed for 0.5-4 hours to effectively improve the uniformity of the reinforcement particles in the aluminum matrix;

[0036] The semi-solid strong shear stirring in step (4) has a significant effect on improving the wettability of the interface between the reinforcement particles and the aluminum matrix, promoting the breakup of agglomerated particles, and improving the dispersion uniformity of the reinforcement phase particles.

[0037] The present invention further divides the addition of reinforcing phase particles into two parts: (3) the addition of reinforcing phase particles and (4) the homogenization of the particles of the composite material melt. In part (3), a two-stage stirring design is used to promote the smooth addition of reinforcing phase particles and their entry into the melt through a downward pressure flow field, laying a foundation for the homogenization of the next step; in part (4), a strong shearing effect is generated by high-speed stirring, which effectively breaks up the particle agglomeration generated during the addition process of step (2), further increasing the uniformity of the reinforcing phase particles in the melt; through the combination of (3) and (4), the addition of reinforcing phase particles and the homogenization are matched, and a uniform melt with a high content of reinforcing phase particles, uniform distribution and no defects such as air entrainment is obtained. As a result, the reinforcing phase particles of the composite material finally prepared are evenly dispersed in the aluminum matrix, and the reinforcing phase particles are tightly bonded to the aluminum matrix interface and have good wettability.

[0038] In order to adjust the structure size of the casting, in the bottom casting of step (5), the cooling water flow rate can be adjusted by a flow valve so that the water temperature at the water outlet ranges from 35 to 50°C.

[0039] In order to ensure the uniformity of composition and improve the performance, preferably, the subsequent heat treatment in step (6) includes the following steps: solution treatment at 510-540°C for 6-9h, and then aging treatment at 150-170°C for 4-7h.

[0040] Preferably, the step (2) specifically comprises the following steps: placing ingredients according to the required aluminum alloy ratio into a smelting container (2), evacuating to 10-100 Pa and then stopping evacuating, filling with inert gas protection gas to 200-600 Pa, and then heating to 700-800° C., keeping the temperature for 0.5-2 hours, so that the ingredients are completely melted. The low vacuum in this step greatly shortens the working hours and improves production efficiency.

[0041] In order to obtain better wear resistance and matching strength and plastic toughness, preferably, the amount of reinforcement phase particles added in the present invention is 5-30% by volume. The present invention can use any micron-sized reinforcement phase particles, such as ceramic phases such as silicon carbide, aluminum oxide, boron carbide, boron nitride, chromium oxide, as well as diamond, graphite, etc. In order to obtain better wear resistance, silicon carbide is preferred. The present invention uses reinforcement phase particles with a particle size range of 5-30μm. In order to achieve uniform distribution of particles and optimization of performance, the preferred reinforcement phase particle size range is 8-15μm.

[0042] The present invention can select any cast aluminum alloy matrix such as A356, A357, A359, A360, 2025, 6061, etc. In order to obtain better wear resistance, the preferred aluminum alloy matrix is ​​A357 and A359.

[0043] Compared with the prior art, the advantages of the present invention are:

[0044] For the bottom casting device of the present invention:

[0045] 1. The bottom casting device of the present invention is a gravity casting device with high casting efficiency, simple device and low manufacturing cost;

[0046] 2. The bottom casting device of the present invention, under the protection of the protective gas inside the furnace body, utilizes the movable platform, mold, and waste slag tank to separate the uniform melt in the front part from the melt in the rear part containing slag. The melt in the front part has less gas entrainment, fewer pores, and uniform particle distribution; the melt in the rear part has more gas entrainment and serious particle agglomeration. Therefore, selecting the melt in the front part can effectively reduce casting defects and particle agglomeration, thereby obtaining uniform and dense castings and improving the casting performance of composite materials;

[0047] 3. Use bottom casting with a stirring device and keep stirring during the melt casting process to avoid the sedimentation of the reinforcement phase particles, thereby maintaining the overall uniformity of the melt and reducing the performance deviation of different parts of the casting.

[0048] 4. For the casting of aluminum-based composite materials, if various stopper-type and valve-type bottom injection controls are used, the following problems will arise: ① When the tightly matched stopper and valve move, it is easy to rub against the crucible repeatedly to produce debris and then be drawn into the flowing melt. Eventually, it causes alloy contamination and casting defects such as inclusions; ② Tight fit at high temperature requires high precision of parts. Repeated friction will cause the matching parts to gradually fail, and the matching life is low. Once failure occurs, there will be a risk of melt leakage, affecting personal safety; ③ After each furnace is cast, due to the high viscosity of the composite melt, more melt or reinforcement will adhere to the runner and seals, such as stopper rods and valves. These residues are easy to contaminate the melt and make the seals fail during the next furnace casting process, making bottom casting impossible.

[0049] The bottom casting of the bottom casting device of the present invention is achieved by breaking the broken segments of the casting head. A new casting head can be replaced after each use, which can ensure the effectiveness of the seal and ensure safety; prevent the adhesion of the melt or the reinforcing phase, and ensure that the melt cast at the bottom of each furnace can flow out smoothly without involving other pollutants, thereby improving the casting performance of the composite material;

[0050] 5. The waste slag tank is used to collect the broken section and the latter part of the melt, which simplifies the device structure, facilitates cleaning and improves production efficiency;

[0051] 6. A cooling system is set at the bottom of the mold to generate a more directional solidification heat flow, which weakens the tendency of paste solidification and reduces the difficulty of shrinkage compensation caused by paste solidification, thereby reducing solidification defects such as shrinkage and shrinkage holes.

[0052] 7. The cooling system improves the cooling rate, effectively refines the grains and improves the casting performance. At the same time, SiC and other reinforcing phases will be distributed at the grain boundaries of the primary phase during the solidification process. Increasing the cooling rate increases the grain boundaries to better accommodate SiC and other reinforcing phases, and makes SiC and other reinforcing phases evenly distributed.

[0053] For the bottom casting method of the present invention:

[0054] 1. The present invention uses the aforementioned bottom casting device to separate the front part of the uniform melt from the rear part of the melt containing slag. The front part of the melt has a light degree of gas entrainment, few pores, and uniform particle distribution; the rear part of the melt has more gas entrainment and serious particle agglomeration. Therefore, selecting the front part of the melt can effectively reduce casting defects and particle agglomeration, thereby obtaining uniform and dense castings and improving the casting performance of composite materials;

[0055] 2. The bottom casting device used in the present invention is simple to operate, convenient for operators to operate, and can smoothly separate the front part of the melt from the rear part of the melt. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a schematic diagram of the overall structure of the bottom casting device of an embodiment of the present invention;

[0057] Figure 2 A schematic structural diagram of a cooling plate according to an embodiment of the present invention;

[0058] Figure 3 A schematic structural diagram of a stirring rod according to an embodiment of the present invention;

[0059] Figure 4 The metallographic structure of the aluminum-based composite material of an embodiment of the present invention;

[0060] Figure 5 This is a scanning electron microscope image of the reinforcement / aluminum matrix interface of the aluminum-based composite material according to an embodiment of the present invention. DETAILED DESCRIPTION

[0061] The specific implementation of the present invention is further described in detail below in conjunction with the drawings and examples.

[0062] like Figure 1-3 As shown, the bottom casting device for preparing particle-reinforced aluminum-based composite materials includes a furnace body 1, a smelting container 2 is arranged in the furnace body 1, and the bottom of the smelting container 2 is a casting port 21 with a melt flow channel; the smelting container 2 is equipped with a secondary feeding device 3, a heating and temperature control device, a stirring device 4, a vacuum device 5, a thermocouple 6 for temperature measurement, and a tamping rod 7.

[0063] A casting head 8 is replaceably mounted with the casting port 21, and the casting head 8 includes a mounting section 81 for cooperating with the melt flow channel, and a fragile fragmentation section 82; an impact device 9 for breaking the fragmentation section 82 is arranged in the furnace body 1; a movable platform 10 is arranged at the bottom of the furnace body 1, and a mold 101 and a waste slag trough 102 are arranged on the movable platform 10; when the movable platform 10 is in the first position, the waste slag trough 102 is used to receive the broken fragmentation section 82, and the mold 101 is used to receive the front part of the uniform melt flowing out of the casting head 8; when the movable platform 10 is in the second position, the waste slag trough 102 is used to receive the rear part of the melt containing slag; a cooling system is arranged at the corresponding position of the movable platform 10 and the bottom of the mold 101. The waste slag trough 102 of this embodiment has a trumpet-shaped opening.

[0064] In order to better keep warm, the smelting container 2 is a graphite crucible.

[0065] In order to ensure the sealing performance during smelting and prevent blockage when the melt flows out, the ratio of the diameter of the casting port 21 of the casting head 8 to the diameter of the smelting container 2 is 1:10. In order to facilitate the replacement and disassembly of the casting head 8, the mounting section 81 of the casting head 8 is an external thread section, so as to be matched and connected with the internal thread corresponding to the melt flow channel. The mounting section 81 and the crushing section 82 of the casting head 8 can be made of different materials or the same material. In order to reduce costs, the casting head 8 is made of graphite, and the wall thickness of the mounting section 81 is greater than the wall thickness of the crushing section 82.

[0066] For the convenience of operation, the impact device 9 preferably includes an impact head 91 and a cylinder 92 connected to the impact head 91 .

[0067] In order to facilitate the adjustment of the cooling speed, the cooling system includes a cooling plate 103 located on the movable platform 10, a water cooling channel is provided in the cooling plate 103, and a flow valve for adjusting the flow rate is provided at the water inlet of the water cooling channel. Figure 2 The cooling water flow can be adjusted by the flow valve to make the water temperature at the water outlet 35-50℃.

[0068] In order to simplify the structure and facilitate operation, the movable platform 10 includes a bottom plate and a slide rail on which the bottom plate is installed.

[0069] In order to prevent the melt from being blocked at the outlet, the heating wire of the first heating and temperature control device wraps the outer peripheral surface of the main body of the smelting container 2 and the outer peripheral surface of the casting port 21 .

[0070] In order to make the particle addition more efficient and uniform, the secondary feeding device 3 of this embodiment includes a secondary hopper 31 , a screw feeder 32 arranged in cooperation with the secondary hopper 31 , and a resistance heating temperature control device arranged in cooperation with the secondary hopper 31 .

[0071] The stirring device 4 includes a stirring rod 41 located in the middle of the smelting container 2, a driving motor for driving the stirring rod 41, and a plurality of blade layers are arranged on the stirring rod 41, including a spiral blade layer 42 and a prismatic blade layer 43. The prismatic blade layer 43 includes a plurality of blade layers arranged along the circumference of the stirring rod 41, and the cross-sectional polygon of the prismatic blade 431 has at least one internal angle in the range of 30-60°. The stirring rod 41 of this embodiment is provided with three blade layers in sequence, the first and third blade layers are both spiral blade layers 42, and the second layer is a prismatic blade layer 43. The prismatic blade 431 is in the shape of a right quadrangular prism, including two internal angles of 30° and two internal angles of 150°. The four prismatic blades 431 are evenly spaced and arranged on the same horizontal plane.

[0072] The bottom casting method for preparing a particle-reinforced aluminum-based composite material using the above-mentioned bottom casting device includes the following steps: the composition ratio of the aluminum alloy matrix of this embodiment is: Mg content is 1%, Si content is 10%, and the rest is Al; the reinforcing phase particles are: SiC particles, with a volume fraction of 20% and a particle size of 15μm.

[0073] (1) Pretreatment of SiC particles: Weigh a proportion of SiC particles, clean them with a 5% HF solution for 24 hours, then wash them with water in an ultrasonic cleaner until they are neutral, place them in a box-type resistance furnace and keep them at 170° C. for 7 hours for drying, sieve the dried powder with a vibrating screen, place them in a secondary hopper 31 and preheat them at 200° C. for standby use.

[0074] (2) Preparation and smelting of AlMgSi alloy: Put weighed pure Al, pure Mg and Al-Si master alloy into the graphite crucible, start the vacuum device 5 to evacuate the furnace to a vacuum degree of 10-20 Pa, stop evacuating, and fill the furnace with inert gas protection gas to 300-400 Pa. Turn on the heating temperature control device to heat to 750°C and keep warm for 0.5 hours to ensure that the melt in the crucible is completely melted.

[0075] (3) Addition of SiC particles.

[0076] The first stage of stirring: the oxide scale and other slag on the surface of the melt are scraped off by the pounding rod 7, and the stirring rod 41 is lowered into the melt. In order to ensure the uniformity of the melt composition and remove the entrapped gas in the melt, the stirring device 4 stirs at a low speed of less than 300r / min until the temperature drops to the semi-solid range of 0-20°C below the liquidus.

[0077] Second stage stirring: the speed of the stirring device 4 is increased to 400r / min, so that a stirring vortex is formed on the surface of the aluminum liquid. The reinforcing phase particles are added to the center of the vortex through the screw feeder 32. The feeding situation and the liquid level are observed in real time through the observation window, and the feeding speed is controlled to ensure uniform feeding.

[0078] (4) Particle homogenization of composite material melt.

[0079] Semi-solid strong shear stirring: After the reinforcement phase particles are completely added, the temperature is controlled in the range of 0-20°C below the liquidus line, the speed of the stirring device 4 is increased to 900r / min, and high-speed strong shear stirring is performed for 1-2 hours to make the reinforcement phase particles evenly dispersed, effectively enhancing the interface wettability between the aluminum matrix and the reinforcement phase particles.

[0080] (5) Bottom casting: To ensure the uniform distribution of the reinforcing phase in the melt during the casting process, after heating to the casting temperature, maintain a stirring speed of 800r / min to start bottom casting. Use the impact device 9 to break the fragmentation segment 82, and the fragments of the fragmentation segment 82 fall into the waste slag trough 102. The mold 101 receives the front part of the uniform melt flowing out of the casting port 21. At the same time, turn on the cooling system to cool the mold 101. The flow valve adjusts the cooling water flow so that the water temperature range of the water outlet is 40°C. Observe the degree of drop in the melt level through the observation window. When the viscosity of the flowing liquid increases, it means that the front part of the uniform melt has flowed out more fully. Move the movable platform 10 so that the waste slag trough 102 is placed at the casting port 21 to receive the rear part of the melt containing slag flowing out of the casting port 21;

[0081] (6) Subsequent heat treatment:

[0082] The obtained ingot was solution treated at 538°C for 8 h and aged at 160°C for 5 h.

[0083] The metallographic structure of the aluminum-based composite material manufactured by the present invention is as follows: Figure 4 As shown in the figure, it can be seen that the SiC in the prepared aluminum-based composite material is evenly dispersed, there is no SiC agglomeration, no casting defects, and the SiC / Al interface is tightly bonded.

[0084] Figure 5 This is a scanning electron microscope image of the reinforcement / aluminum matrix interface of the aluminum-based composite material manufactured by the present invention. ， It can be seen from the figure that the SiC in the prepared aluminum-based composite material is evenly dispersed and the SiC / Al interface is tightly bonded.

[0085] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. A bottom casting device for preparing a particle-reinforced aluminum-based composite material, comprising a furnace body (1), a smelting container (2) arranged in the furnace body (1), and a bottom of the smelting container (2) having a melt flow channel Casting mouth (21) The smelting container (2) is provided with a secondary feeding device (3), a heating temperature control device, and a stirring device (4), characterized in that: With the casting port (21) A casting head (8) is replaceably mounted, the casting head (8) comprising a The melt flow channel The furnace body (1) is provided with an impact device (9) for breaking the breaking segment (82); a movable platform (10) is provided at the bottom of the furnace body (1), and a mold (101) and a waste slag groove (102) are provided on the movable platform (10); when the movable platform (10) is located at a first position, the waste slag groove (102) is used to receive the broken breaking segment (82), and the mold (101) is used to receive the waste slag from the breaking segment (82). Casting head(8) The front part of the outflow Uniform melt, when the movable platform (10) is located at the second position, the waste slag tank (102) is used to receive the rear part of the melt containing slag; The A cooling system is provided at a position corresponding to the bottom of the mold (101) and the movable platform (10). .

2. The bottom casting device according to claim 1, characterized in that: The mounting section (81) of the casting head (8) is an external thread section, so that The melt flow channel corresponds to the internal thread matching connection.

3. The bottom casting device according to claim 2, characterized in that: The ratio of the diameter of the pouring port (21) of the pouring head (8) to the diameter of the smelting container (2) is 1:5 to 1:

15.

4. The bottom casting device according to claim 2, characterized in that: The casting head (8) is made of graphite, and the wall thickness of the mounting section (81) is greater than the wall thickness of the fragmentation section (82).

5. The bottom casting device according to claim 1, characterized in that: The impact device (9) comprises an impact head (91) and a cylinder (92) connected to the impact head (91).

6. The bottom casting device according to any one of claims 1 to 5, characterized in that: The stirring device (4) comprises a stirring rod (41) located in the middle of the smelting container (2), and a driving motor for driving the stirring rod (41). The stirring rod (41) is provided with a plurality of blade layers, including a spiral blade layer (42) and a prismatic blade layer (43). The prismatic blade layer (43) comprises a plurality of prismatic blades (431) arranged along the circumference of the stirring rod (41), and the cross-sectional polygon of the prismatic blade (431) has at least one internal angle in the range of 30-60°.

7. A bottom casting method for preparing a particle-reinforced aluminum-based composite material, using the bottom casting device according to any one of claims 1 to 5, characterized in that The following steps are involved: (1) After pretreatment, the reinforcing phase particles are placed in the secondary feeding device (3) for preheating; (2) Preparation and smelting of aluminum-based alloy: placing the ingredients according to the required aluminum alloy ratio into the smelting container (2), evacuating the container and introducing protective gas, and turning on the heating and temperature control device to completely melt the ingredients; (3) Addition of reinforcing phase particles: Turn on the stirring device (4), and when the temperature reaches a semi-solid range of 5-50°C below the liquidus, use the secondary feeding device (3) to add reinforcing phase particles; (4) Particle homogenization of composite melt: After the reinforcing phase particles are added, the temperature is controlled in the range of 0-40°C below the liquidus line and stirred until uniform; (5) Bottom casting: heating to the casting temperature, maintaining the stirring speed at 300-1500 r / min during the bottom casting process, using the impact device (9) to break the fragmentation segment (82), and the fragments of the fragmentation segment (82) fall into the waste slag tank (102), and the mold (101) receives the front part flowing out of the casting port (21). Uniform melt, and at the same time, the cooling system is turned on to cool the mold (101); the degree of drop of the melt level is observed through the observation window, and when the viscosity of the melt flowing out of the casting port (21) increases, the front part Uniform When the melt has flowed out sufficiently, the movable platform (10) is moved so that the slag trough (102) is placed at the casting port (21) to receive the rear part of the melt containing slag; (6) Subsequent heat treatment.

8. The bottom casting method according to claim 7, characterized in that: The pretreatment of step (1) comprises the following steps: acid-washing the reinforcing phase particles and then washing with water until they are neutral, then drying them at a temperature of 100-200° C., and then sieving to obtain reinforcing phase particles.

9. The bottom casting method according to claim 7, characterized in that: The subsequent heat treatment in step (6) comprises the following steps: solution treatment at 510-540° C. for 6-9 hours, and then aging treatment at 150-170° C. for 4-7 hours.

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