Anti-gravity casting device and process for metal-based composite foam material

Abstract

The invention provides an anti-gravity casting device and technology for a metal-based composite foam material, the anti-gravity casting device comprises a casting forming system, a melt liquid lifting system and a metal smelting system, the casting forming system comprises an upper furnace chamber, a mold is arranged in the upper furnace chamber, a ceramic hollow ball is arranged in the mold, and the melt liquid lifting system comprises a liquid lifting pipe and a lifting device; the metal smelting system comprises a crucible and a lower furnace chamber, molten metal is arranged in the crucible, the mold and the crucible are communicated through the liquid rising pipe, and the lifting device is connected with the upper furnace chamber and the lower furnace chamber. And the molten metal overcomes the gravity of the molten metal and permeates into the ceramic hollow ball stack from bottom to top, and the metal-based composite foam material with the hollow ball reinforced particles evenly distributed is obtained. According to the casting method, most of residual gas in gaps of the hollow balls can be removed, defects in castings are reduced, and the mechanical property of the composite foam can be improved.

Description

Technical Field

[0001] This invention belongs to the field of metal matrix composite material manufacturing, specifically relating to a metal matrix composite foam material and its anti-gravity casting process and anti-gravity casting equipment. Background Technology

[0002] Metal-based composite foams, due to their low density, high compressive strength, excellent energy absorption capacity, and good ductility, have great potential in transportation, aerospace, and national defense. As a structural material, metal-based composite foams can effectively reduce equipment weight and energy consumption; as a functional material, they can absorb sound and noise, provide thermal insulation, explosion protection and vibration reduction, and buffer and absorb energy, making them an ideal integrated structural and functional material. Therefore, developing a metal-based composite foam material preparation device to meet the practical needs of weight reduction, energy saving, and protective energy absorption in transportation has broad application prospects.

[0003] Currently, the main domestic and international method for preparing metal-based composite foam materials is infiltration casting. This technology is characterized by its high operability, low cost, and ease of industrialization. In the melt infiltration casting process, a certain volume of filler particles are loosely or tightly packed in a mold. The molten metal flows into the pores of the filler particle stack under pressureless, externally pressurized, or vacuum conditions and eventually solidifies to obtain composite foam. The melt infiltration casting process can achieve a uniform distribution of filler particles within the composite foam. Compared to stirred casting, it does not require additional compensation processes; compared to powder metallurgy, it does not introduce a large amount of residual porosity. This process is particularly suitable for preparing composite foams with a high volume fraction of reinforcing particles. However, it also requires high control of process parameters. For example, the infiltration pressure and temperature cannot be too low, otherwise the molten metal will solidify prematurely, leading to insufficient infiltration. Conversely, excessively high infiltration pressure or temperature may cause the filler particles to break, resulting in the molten metal infiltrating into the hollow spheres, which is detrimental to the overall performance of the metal-based composite foam. Traditional flow casting processes often employ a top-down filling method, which easily leads to various defects in the resulting composite foam, such as "insufficient flow" or "excessive flow." Anti-gravity flow casting technology, developed in the 1950s, is a special metal liquid forming process. It involves using pressure to force molten metal in a crucible to overcome gravity and frictional resistance as it flows upwards through a riser pipe to fill the mold, thus obtaining the casting under pressure. This method is widely used to produce large, complex, thin-walled components, and the resulting castings have fewer defects and porosity. Summary of the Invention

[0004] The purpose of this invention is to provide an anti-gravity casting method for metal-based composite foam materials. This invention mainly utilizes a low-vacuum environment and a pressure-differential anti-gravity filling and solidification method to effectively remove gas from the stack of hollow ceramic spheres, reduce defects in the composite foam casting, and obtain higher mechanical properties.

[0005] This invention is achieved using the following technical solution: a method for anti-gravity casting of metal-based composite foam materials proposed in this invention includes the following steps:

[0006] Step 1: Fill the mold in the upper furnace chamber with hollow spherical particles and pack them tightly. Fill the crucible in the lower furnace chamber with metal blocks. Raise the lifting device to the highest point and evacuate the upper and lower furnace chambers to a low vacuum state.

[0007] Step 2: Activate the induction heating device to melt the metal in the crucible into liquid metal. Keep it at a constant temperature for a period of time. After the metal has fully melted, use the lifting device to lower the riser pipe below the liquid metal surface.

[0008] Step 3: Turn on the mold heating device and the riser pipe heating jacket to preheat the mold and riser pipe, and keep them warm for a period of time;

[0009] Step 4: Compressed gas is introduced into the lower furnace chamber using a compressed gas tank. Under the pressure difference between the lower and upper furnace chambers, the liquid metal enters the mold containing hollow spherical particles along the riser pipe.

[0010] Step 5: After filling, maintain pressure for a certain period of time to eliminate defects in the casting. After the liquid metal solidifies, release the pressure, open the upper furnace cavity and take out the casting to obtain hollow sphere reinforced metal matrix composite foam material.

[0011] Furthermore, in step 1, the hollow spheres are either ceramic hollow spheres or metal hollow spheres. The ceramic hollow spheres can be one or more of the following: alumina hollow spheres, zirconia hollow spheres, silica hollow spheres, silicon carbide hollow spheres, silicon nitride hollow spheres, or mullite hollow spheres. The metal hollow spheres can be stainless steel hollow spheres. The particle size of the hollow spheres ranges from 0.5 mm to 10 mm.

[0012] Furthermore, in step 1, the metal is an aluminum alloy, magnesium alloy, zinc alloy, iron alloy, or titanium alloy, and the aluminum alloy is one or more of the following: A356, A357, ZL101, and ZL104.

[0013] Furthermore, in step 2, the aluminum alloy melting temperature is 750 ℃ ​​- 770 ℃.

[0014] Furthermore, in step 3, the preheating temperature of the mold and riser pipe is 500 ℃ - 520 ℃.

[0015] Furthermore, in step 4, the filling pressure is 0.05 MPa - 0.4 MPa, and the compressed gas is high-purity argon.

[0016] Furthermore, the pressure holding time in step 5 is 80 s - 100 s.

[0017] Therefore, the anti-gravity casting device and process for metal-based composite foam materials of the present invention have the following beneficial effects:

[0018] 1. The present invention provides an anti-gravity casting device and process method for metal-based composite foam materials, which utilizes the pressure difference between the upper and lower furnace chambers to allow molten metal to flow from bottom to top into the mold. Compared with gravity casting, this flow method can effectively remove residual air from the stack of ceramic hollow spheres and reduce the occurrence of unintended pores in the hollow sphere-filled metal-based composite foam material castings.

[0019] 2. In the anti-gravity casting device and process method for metal-based composite foam material provided by the present invention, the graphite riser tube is designed to be detachable. That is, a threaded structure is used for assembly at the position where the inner diameter of the riser tube begins to change, so that partial replacement can be performed in case of blockage of the riser tube. This is beneficial to improving the convenience of equipment maintenance and significantly reducing maintenance costs.

[0020] 3. The vacuum anti-gravity percolation casting process adopted in this invention realizes the filling, crystallization and feeding of molten metal under controllable pressure. It can effectively eliminate casting defects such as shrinkage cavities and porosity in gas preparation processes of metal-based composite foam castings, and solve the problems of unstable filling and difficult process control in traditional percolation methods.

[0021] 4. The hollow sphere reinforced metal matrix composite foam material prepared by the present invention has uniformly distributed hollow spheres inside, and has low density, high specific strength and good energy absorption capacity. With its excellent energy absorption and impact resistance, it can be widely used in transportation, national defense and military industry and aerospace fields. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the anti-gravity casting device and process for a metal-based composite foam material according to the present invention.

[0023] Figure 2 This is a schematic diagram showing the lifting device's rising position in the anti-gravity casting device and process for a metal-based composite foam material according to the present invention.

[0024] Figure 3 The riser pipe of the anti-gravity casting device and process for a metal-based composite foam material of the present invention is shown in cross-sectional view.

[0025] In the diagram: 1. Upper furnace chamber; 2. Exhaust vent; 3. Mold; 4. Hollow spherical particles; 5. Mold heating device; 6. Filter screen; 7. Heating jacket for riser pipe; 8. Riser pipe; 9. Lifting device; 10. Vacuum pump; 11. Compressed gas tank; 12. Sealing ring; 13. Crucible; 14. Induction heating device; 15. Molten metal; 16. Lower furnace chamber; 801. Conical inlet; 802. Variable diameter top pipe; 803. Constant diameter bottom pipe. Detailed Implementation

[0026] The specific structure, working principle, and working process of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] Example

[0028] This embodiment designs an anti-gravity casting device for metal-based composite foam materials, such as... Figure 1 As shown, the system includes a casting forming system, a melt lifting system, and a metal smelting system. The casting forming system includes an upper furnace chamber 1, an exhaust port 2, a mold 3, hollow spherical particles 4, a mold heating device 5, and a filter screen 6. The melt lifting system includes a lifting pipe heating sleeve 7, a lifting pipe 8, a lifting device 9, a vacuum pump 10, and a compressed air tank 11. The metal smelting system includes a sealing ring 12, a crucible 13, an induction heating device 14, molten metal 15, and a lower furnace chamber 16.

[0029] Mold 3 is located inside the upper furnace chamber 1. Its upper end has an exhaust port 2 to discharge gas from the hollow sphere particles 4 during the seepage process. Mold heating devices 5 are arranged around the mold 3, consisting of heating tubes evenly surrounding the outer layer. A filter screen 6 is located at the bottom opening. A lifting device 9 connects the upper furnace chamber 1 and the lower furnace chamber 16, controlling the lifting and lowering of the upper furnace chamber 1. The cylinder of the lifting device 9 is fixed to the upper surface of the lower furnace chamber 16, and the cylinder rod is fixed to the upper furnace chamber 1. One end of the riser pipe 8 is connected to the filter screen 6, and the other end extends into the lower furnace chamber 16. A heating sleeve 7 surrounds the riser pipe 8. A vacuum pump 10 is connected to the upper furnace chamber 1 and the lower furnace chamber 16 via a gas guide pipe. A compressed air tank 11 is connected to the lower furnace chamber 16 via a gas guide pipe. A sealing ring 12 is provided between the lower furnace chamber 16 and the heating sleeve 7 of the riser pipe. The lower cavity 16 contains a crucible 13, and an induction heating device 14 is provided around the crucible 13. The induction heating device 14 is a spiral induction coil, and the crucible 13 is filled with a metal block.

[0030] The riser pipe 8 features a detachable design, consisting of a tapered inlet 801, a reducing pipe 802, and a constant-diameter pipe 803, arranged from top to bottom. Each section is connected by a threaded structure. The inner diameter of the upper end of the reducing pipe 802 is larger than that of the lower end, while the inner diameter of the constant-diameter pipe 803 is smaller than that of the lower end of the reducing pipe 802. Figure 3 As shown.

[0031] This invention also provides an anti-gravity casting process for metal-based composite foam materials, the casting process comprising the following steps:

[0032] Step 1: Prepare hollow spherical particles 4 and aluminum alloy raw materials, and fill them into the mold 3 and the crucible 13 in the lower furnace cavity 16 respectively. The hollow spherical particles 4 are packed tightly, and at the same time, the lifting device 9 is raised to the highest point. Figure 2 As shown, start the vacuum pump 10 and evacuate the upper furnace chamber 1 and the lower furnace chamber 16 to a low vacuum state;

[0033] Specifically, the hollow spheres 4 are either ceramic or metal hollow spheres. The ceramic hollow spheres can be one or more of the following: alumina hollow spheres, zirconia hollow spheres, silicon dioxide hollow spheres, silicon carbide hollow spheres, silicon nitride hollow spheres, or mullite hollow spheres. The metal hollow spheres can be stainless steel hollow spheres. The particle size range of the hollow spheres is 0.5 mm - 10 mm. Aluminum alloys such as A356, A357, ZL101, and ZL104 can be used. Other metals can be magnesium alloys, zinc alloys, iron alloys, and titanium alloys.

[0034] Step 2: Activate the induction heating device 14 to melt the aluminum alloy raw material in the crucible 13 into liquid metal 15. Maintain the temperature and let it stand for a period of time. After the metal has fully melted, use the lifting device 9 to lower the riser pipe 8 below the surface of the liquid metal 15. Figure 1 As shown;

[0035] Specifically, the melting temperature of aluminum alloy is 750 ℃ ​​- 770 ℃.

[0036] Step 3: Start the mold heating device 5 and the riser pipe heating sleeve 7 to preheat the mold 3 and riser pipe 8, and keep them warm for a period of time.

[0037] Specifically, the preheating temperature of the mold and riser pipe is 500 ℃ - 520 ℃.

[0038] Step 4: Inert protective gas is introduced into the lower furnace chamber 16 using the compressed gas tank 11. Under the pressure difference between the lower furnace chamber 16 and the upper furnace chamber 1, the liquid aluminum alloy enters the mold 3 containing the ceramic hollow ball 4 along the riser pipe 8.

[0039] Specifically, the filling pressure is 0.05 MPa - 0.4 MPa, and the compressed gas is high-purity argon.

[0040] Step 5: After filling, maintain pressure for a period of time to eliminate defects in the casting. After the molten metal solidifies, release the pressure, open the upper furnace chamber 1, and take out the casting to obtain the metal-based composite foam material.

[0041] Specifically, the pressure holding time is 80 s - 100 s.

[0042] The final silicon carbide hollow sphere / A356 aluminum-based composite foam material exhibits uniform distribution of silicon carbide hollow spheres, with a volume fraction of 2.36%–5.10% for defects within the composite foam. The aluminum-based composite foam material achieves a compressive strength of 91.42 MPa, a plateau stress of 65.97 MPa, and an energy absorption capacity of 33.49 J·cm⁻¹. -3 The specific energy absorption reaches 22.00 J·g. -1 .

[0043] This invention discloses an anti-gravity casting device for metal-based composite foam materials. By utilizing the pressure difference between the upper furnace chamber 1 and the lower furnace chamber 16, the molten metal in the crucible 13 overcomes its own gravity and flows upward into the mold 3. The upward flow method helps to drive away residual gas in the gaps between the stacked ceramic hollow spheres, which helps to reduce defects in the composite foam casting and improve the overall mechanical properties of the material.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the design and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. An anti-gravity casting device for metal-based composite foam materials, characterized in that: The system includes a casting forming system, a melt lifting system, and a metal smelting system. The casting forming system includes an upper furnace chamber (1), an exhaust port (2), a mold (3), a mold heating device (5), and a filter screen (6). The melt lifting system includes a lifting pipe heating sleeve (7), a lifting pipe (8), a lifting device (9), a vacuum pump (10), and a compressed air tank (11). The metal smelting system includes a sealing ring (12), a crucible (13), an induction heating device (14), and a lower furnace chamber (16).

2. The anti-gravity casting device for a metal-based composite foam material according to claim 1, characterized in that, The upper furnace chamber (1), the mold heating device (5) and the mold (3) are nested from the outside to the inside. The mold (3) is provided with an exhaust hole (2) and a filter screen (6) at the upper and lower ends, respectively. The upper furnace chamber (1) and the lower furnace chamber (16) are connected by a riser pipe (8). The riser pipe (8) is wrapped with a riser pipe heating sleeve (7). The vacuum pump (10) is connected to the upper furnace chamber (1) and the lower furnace chamber (16) through a gas guide pipe. The compressed gas tank (11) is connected to the lower furnace chamber (16) through a gas guide pipe. A sealing ring is provided between the lower furnace chamber (16) and the riser pipe heating sleeve (7). A crucible (13) is provided inside the lower cavity (16). An induction heating device (14) is provided around the crucible (13).

3. The anti-gravity casting device for a metal-based composite foam material according to claim 1, characterized in that, The mold (3), the riser pipe (8) and the crucible (13) are made of isostatic graphite.

4. The anti-gravity casting device for a metal-based composite foam material according to claim 1, characterized in that, The inner diameter of the riser tube (8) is designed with a variable diameter structure, and the inner diameter shape is funnel-shaped, and each section is a detachable structure.

5. A casting process using an anti-gravity casting device for a metal-based composite foam material as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Fill the hollow spheres into the mold (3) of the upper furnace chamber (1) and stack them tightly. Fill the metal raw material into the crucible (13) of the lower furnace chamber (16). Raise the lifting device (9) to the highest point and evacuate the upper furnace chamber (1) and the lower furnace chamber (16) to a low vacuum state. Step 2: Start the induction heating device (14) to melt the metal in the crucible (13) into liquid metal, keep it warm and stand for a period of time, and after the metal has been fully melted, use the lifting device (9) to lower the liquid riser (8) below the liquid metal surface; Step 3: Turn on the mold heating device (5) and the riser pipe heating sleeve (7) to preheat the mold (3) and the riser pipe, and keep them warm for a period of time; Step 4: Compressed gas is introduced into the lower furnace chamber (16) using the compressed gas tank (11). Under the pressure difference between the lower furnace chamber (16) and the upper furnace chamber (1), the liquid metal enters the mold (3) containing hollow spherical particles along the riser pipe (8). Step 5: After filling the mold, maintain pressure for a certain period of time to eliminate defects in the casting. After the aluminum liquid solidifies and forms, release the pressure, open the upper furnace cavity (1), take out the casting, and obtain the metal-based composite foam material.

6. The anti-gravity casting process for a metal-based composite foam material according to claim 5, characterized in that, In step 1, the hollow spheres are either ceramic hollow spheres or metal hollow spheres. The ceramic hollow spheres are one or more of the following: alumina hollow spheres, zirconia hollow spheres, silica hollow spheres, silicon carbide hollow spheres, silicon nitride hollow spheres, or mullite hollow spheres. The metal hollow spheres are stainless steel hollow spheres. The particle size of the hollow spheres ranges from 0.5 mm to 10 mm.

7. The anti-gravity casting process for a metal-based composite foam material according to claim 5, characterized in that, In step 1, the metal is an aluminum alloy, magnesium alloy, zinc alloy, iron alloy, or titanium alloy, and the aluminum alloy is one or more of the following: A356, A357, ZL101, and ZL104.

8. The anti-gravity casting process for a metal-based composite foam material according to claim 5, characterized in that, In step 2, the aluminum alloy melting temperature is 750 ℃ ​​- 770 ℃, and in step 3, the preheating temperature of the aluminum mold and riser pipe is 500 ℃ - 520 ℃.

9. The anti-gravity casting process for a metal-based composite foam material according to claim 5, characterized in that, In step 4, the filling pressure is 0.05 MPa - 0.4 MPa, and the compressed gas is high-purity argon; in step 5, the pressure holding time is 80 s - 100 s.

10. A hollow sphere reinforced metal matrix composite foam material prepared by the anti-gravity casting method described in claim 5.

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