Integrated forming device and method for Csf / Mg composite material

Abstract

The invention discloses a Csf / Mg composite material integrated forming device which comprises a smelting and infiltration module, movable ultrasonic equipment extending into the smelting and infiltration module and a gas module communicating with the smelting and infiltration module. The smelting and infiltration module comprises smelting equipment and a cavity-divided crucible located in the smelting equipment; a choke plug is arranged at the joint of the upper cavity and the lower cavity of the cavity-divided crucible; the invention further discloses an integral forming method of the Csf / Mg composite material. According to the device, the movable ultrasonic equipment is arranged, ultrasonic vibration is introduced into the whole process of smelting, infiltration and solidification, element segregation in a tissue is avoided, the crucible of a cavity dividing structure is arranged, growth of second-phase particles is effectively restrained, the second-phase particles smoothly penetrate through a porous channel of a prefabricated body, and the mechanical property of the prefabricated body is improved. And segregation of the magnesium alloy melt at the top of the porous carbon fiber preform is prevented, and the method is suitable for the technical field of magnesium-based composite material forming.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnesium matrix composite material forming, and particularly relates to an integral forming device and method for C sf / Mg composite materials. Background Art

[0002] The density of short carbon fiber reinforced magnesium matrix (C sf / Mg) composite material is about 1.8 g / cm 3 or so. While maintaining the lightweight advantage of magnesium alloy, it has high specific strength, high specific modulus, low thermal expansion coefficient and good damping performance. Especially after the introduction of short fibers, the composite material maintains good macroscopic isotropic characteristics and has broad application prospects in the fields of aerospace, weaponry, and civilian electronics. The isotropic property of C sf / Mg composite material is essentially to ensure uniform distribution of the material structure at the microscopic level, which requires uniform dispersion of fibers, no element segregation, pores, oxidation inclusions and other defects inside the structure. Therefore, which C sf / Mg composite material forming device and process can achieve the above goals has always been the common pursuit goal of scholars in this field.

[0003] As is well known, the difficulty of uniform fiber distribution is positively correlated with the fiber content; and according to the mixing rule, the higher the fiber content, the higher the mechanical properties of the composite material. Therefore, it is extremely difficult to prepare C sf / Mg composite materials with high fiber content and high uniformity. Among various current forming methods, the fiber volume content in the stir casting method is generally limited to 10% as the limit, otherwise the fibers are extremely easy to aggregate; the fiber volume content in the ball milling + SPS sintering method usually does not exceed 5%; while using the gravity or pressure infiltration method to make the molten magnesium alloy melt seep into the pre-prepared fiber preform skeleton can break through the fiber dispersion problem and increase the volume content to about 20%, which provides the possibility for the preparation of high-performance C sf / Mg composite materials.

[0004] However, research shows that when using the pressure infiltration method to prepare C with a fiber volume fraction of 20% sfWhen preparing the C / Mg composite material, a fiber volume fraction of 20% will narrow the porous channels in the preform. During the pressure infiltration or solidification of the magnesium alloy melt, severe element segregation behavior will occur. Specifically, the second-phase particles in the magnesium alloy melt cannot pass through the smaller pore channels. After infiltration, there are obvious differences in the particle distribution density in the upper, middle, and lower layers of the preform. Even a second-phase segregation layer with a thickness of about 200 μm is formed at the top of the preform. These distribution differences of the second phase seriously damage the material property uniformity and affect the service life and working safety of the composite material (Journal of Alloys and Compounds, 2023, 935:168083, SCI accession number: WOS:000892689100003). Summary of the Invention

[0005] An object of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a one-piece forming device for C / Mg composite materials. By setting a movable ultrasonic device, ultrasonic vibration is introduced into the whole process of melting, infiltration, and solidification, avoiding element segregation inside the structure. By setting a crucible with a divided cavity structure, the growth of second-phase particles is effectively inhibited and they can smoothly pass through the porous channels of the preform itself, preventing the segregation of the magnesium alloy melt at the top of the porous carbon fiber preform, and solving the problem of obvious differences in the distribution density of C / Mg composite materials with a high fiber volume content. sf / Mg composite material. The one-piece forming device includes a melting and infiltration module, a movable ultrasonic device extending into the melting and infiltration module, and a gas module communicating with the melting and infiltration module. The melting and infiltration module includes a melting device and a divided cavity crucible located inside the melting device. A choke plug is provided at the interface between the upper cavity and the lower cavity of the divided cavity crucible. sf / Mg composite material.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a one-piece forming device for C / Mg composite materials, characterized in that it includes a melting and infiltration module, a movable ultrasonic device extending into the melting and infiltration module, and a gas module communicating with the melting and infiltration module. The melting and infiltration module includes a melting device and a divided cavity crucible located inside the melting device. A choke plug is provided at the interface between the upper cavity and the lower cavity of the divided cavity crucible. sf / Mg composite material. The ultrasonic device is an ultrasonic rod. A bracket is fixedly connected to the ultrasonic rod, and a power mechanism for driving the movement of the bracket is installed on the bracket.

[0007] The above-mentioned one-piece forming device for C sf / Mg composite material, characterized in that the power mechanism includes an electric cylinder connected to the bracket, a servo motor connected to the electric cylinder, and a servo controller electrically connected to the servo motor.

[0008] The above-mentioned one-piece forming device for C sf / Mg composite material, characterized in that the power mechanism includes an electric cylinder connected to the bracket, a servo motor connected to the electric cylinder, and a servo controller electrically connected to the servo motor.

[0009] The above-mentioned one-piece forming device for C sfOne-piece forming device for C / Mg composite material, characterized in that a limiting mechanism is provided on the ultrasonic rod, and the limiting mechanism includes a moving guide sleeve, a guide sleeve bracket fixedly connected to the moving guide sleeve, and a moving frame fixedly connected to the guide sleeve bracket.

[0010] The above-mentioned one C sf One-piece forming device for C / Mg composite material, characterized in that a support platform is provided at the bottom end of the melting equipment.

[0011] The above-mentioned one C sf One-piece forming device for C / Mg composite material, characterized in that the gas module includes a gas cylinder, the gas cylinder is communicated with a trachea, the other end of the trachea is of an annular structure and is located at the top end of the divided cavity crucible, and a plurality of air holes are provided on both the inner and outer sides of the annular structure.

[0012] The above-mentioned one C sf One-piece forming device for C / Mg composite material, characterized in that a fine sand layer is laid in the lower cavity.

[0013] The above-mentioned one C sf One-piece forming device for C / Mg composite material, characterized in that the choke plug is wedge-shaped and the material of the choke plug is graphite.

[0014] The present invention also discloses a C sf One-piece forming method for C / Mg composite material, characterized in that by using the above-mentioned one-piece forming device, the one-piece forming method includes the following steps:

[0015] Step 1: Place the porous carbon fiber preform in the lower cavity of the divided cavity crucible, start the gas module and place the magnesium alloy block in the upper cavity of the divided cavity crucible, and then start the melting equipment to melt the magnesium alloy to obtain a magnesium alloy melt;

[0016] Step 2: Move the ultrasonic equipment to the upper cavity, perform ultrasonic vibration on the magnesium alloy melt obtained in Step 1, then move the ultrasonic equipment downward and press down the choke plug to communicate the upper cavity and the lower cavity, and the ultrasonic equipment stays above the porous carbon fiber preform for ultrasonic vibration, and the magnesium alloy melt infiltrates into the porous carbon fiber preform;

[0017] Step 3: After the infiltration in Step 2 is completed, turn off the heating function of the melting equipment, and the ultrasonic equipment continuously performs ultrasonic vibration until the magnesium alloy melt solidifies to obtain C sf / Mg composite material.

[0018] The present invention has the following advantages compared with the prior art:

[0019] 1. The present invention introduces ultrasonic vibration into the whole processes of melting, infiltration, and solidification by setting a movable ultrasonic device, avoiding element segregation inside the structure, and enabling the infiltration process to proceed under the dual action of "gravity + ultrasonic vibration", thereby improving the infiltration degree. By combining with the setting of a split-cavity crucible, the growth of second-phase particles is effectively inhibited and they can smoothly pass through the porous channels of the preform itself, preventing the segregation layer of the second phase from forming due to the segregation of the magnesium alloy melt at the top of the porous carbon fiber preform, and further improving the performance uniformity of the C sf / Mg composite material.

[0020] 2. The present invention sets an air pipe with an annular structure, with the annular structure located at the top of the split-cavity crucible, capable of forming an atmosphere micro-region at the top of the split-cavity crucible, achieving the atmosphere micro-region protection during the melting process, and achieving a good protection effect at low air pressure and low flow rate, significantly reducing the consumption of protective gas during the preparation process.

[0021] 3. The present invention lays a fine sand layer in the lower cavity, enabling the residual gas in the porous carbon fiber preform to enter the fine sand layer during the infiltration process, avoiding the accumulation of gas at the bottom end of the porous carbon fiber preform and forming a reaction force to hinder infiltration, thereby ensuring the infiltration effect.

[0022] The technical solution of the present invention will be further described in detail below through the drawings and embodiments. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the integrated forming device of the present invention.

[0024] Figure 2 It is a schematic structural diagram of the melting and infiltration module and the ultrasonic device of the present invention.

[0025] Figure 3 It is a schematic structural diagram of the split-cavity crucible of the present invention.

[0026] Figure 4 It is a schematic diagram of the end of the air pipe of the present invention.

[0027] Figure 5 It is the microstructure diagram of the C sf / Mg composite material obtained in Example 2 of the present invention.

[0028] Figure 6 It is the microstructure diagram of the top of the C sf / Mg composite material obtained in Example 2 of the present invention.

[0029] Figure 7 It is the microstructure diagram of the inside of the C sf / Mg composite material obtained in Example 2 of the present invention.

[0030] Figure 8Micrograph of the composite material prepared by the pressure infiltration method.

[0031] Figure 9 Micrograph of the top of the composite material prepared by the pressure infiltration method.

[0032] Figure 10 Micrograph of the inside of the composite material prepared by the pressure infiltration method.

[0033] Explanation of reference numerals:

[0034] 1 - Moving guide sleeve; 2 - Ultrasonic rod; 3 - Bracket;

[0035] 4 - Air pipe; 4-1 - Annular structure; 4-2 - Air outlet;

[0036] 5 - Melting equipment; 6 - Gas cylinder; 7 - Support table;

[0037] 8 - Servo motor; 9 - Moving frame; 10 - Servo controller;

[0038] 11 - Electric cylinder; 12 - Guide sleeve bracket; 13 - Split cavity crucible;

[0039] 13-1 - Upper cavity; 13-2 - Lower cavity; 14 - Magnesium alloy block;

[0040] 15 - Choke plug; 16 - Porous carbon fiber preform; 17 - Fine sand layer. Detailed implementation mode

[0041] Example 1

[0042] As Figures 1 to 3 shown, the one-piece forming device of this embodiment includes a melting and infiltration module, a movable ultrasonic device extending into the melting and infiltration module, and a gas module communicating with the melting and infiltration module. The melting and infiltration module includes a melting device 5 and a split cavity crucible 13 located inside the melting device 5. A choke plug 15 is provided at the interface between the upper cavity 13-1 and the lower cavity 13-2 of the split cavity crucible 13.

[0043] In actual use, in this embodiment, by setting the melting and infiltration module, it is used to melt the magnesium alloy block 14 and infiltrate the porous carbon fiber preform 16; by setting the movable ultrasonic device, ultrasonic vibration is introduced into the whole process of melting, infiltration and solidification to improve the compositional uniformity of the C sf / Mg composite material; by setting the gas module to form a protective gas atmosphere during the preparation process; by setting the melting device 5 to melt the magnesium alloy block 14 and keep the magnesium alloy block 14 in a molten state during the infiltration process; by setting the split cavity crucible 13 as an upper and lower cavity and setting a choke plug 15 at the interface, the melting and infiltration stages can be separated and carried out to achieve C sfIntegral forming of / Mg composite materials; among them, the melting equipment 5 in this embodiment is a pit resistance furnace.

[0044] It should be noted that the bottom end of the lower cavity 13-2 of the multi-chamber crucible 13 in this embodiment is openable and closable for placing the porous carbon fiber preform 16.

[0045] Furthermore, as Figure 1 shown, in this embodiment, the ultrasonic device is an ultrasonic rod 2, a bracket 3 is fixedly connected to the ultrasonic rod 2, and a power mechanism for driving the movement of the bracket 3 is installed on the bracket 3.

[0046] In actual use, in this embodiment, by fixedly connecting the bracket 3 to the ultrasonic rod 2 and installing a power mechanism on the bracket 3, it is used to control the lifting of the ultrasonic rod 2 in the multi-chamber crucible 13.

[0047] Furthermore, as Figure 1 shown, in this embodiment, the power mechanism includes an electric cylinder 11 connected to the bracket 3, a servo motor 8 connected to the electric cylinder 11, and a servo controller 10 electrically connected to the servo motor 8.

[0048] In actual use, in this embodiment, by setting the electric cylinder 11, the servo motor 8 connected to the electric cylinder 11, and the servo controller 10 electrically connected to the servo motor 8, it is used to control the bracket 3 to drive the ultrasonic rod 2 to move up and down; in this embodiment, the electric cylinder 11 and the servo motor 8 are connected through a reducer.

[0049] Furthermore, as Figure 1 shown, in this embodiment, a limiting mechanism is provided on the ultrasonic rod 2, and the limiting mechanism includes a moving guide sleeve 1, a guide sleeve bracket 12 fixedly connected to the moving guide sleeve 1, and a moving frame 9 fixedly connected to the guide sleeve bracket 12.

[0050] In actual use, in this embodiment, by setting the limiting mechanism to prevent the ultrasonic rod 2 from tilting during movement, and by setting the moving guide sleeve 1 and the guide sleeve bracket 12 to fixedly connect the moving guide sleeve 1 and the moving frame 9, it is used to keep the moving guide sleeve 1 stable; it should be noted that in this embodiment, the dimensions of the moving guide sleeve 1 and the end of the ultrasonic rod 2 match, and the ultrasonic rod 2 can smoothly move up and down inside the moving guide sleeve 1.

[0051] Furthermore, as Figure 1 shown, in this embodiment, a support platform 7 is provided at the bottom end of the melting equipment 5.

[0052] In actual use, in this embodiment, by setting the support platform 7, the melting equipment 5 is isolated from the ground.

[0053] Furthermore, as Figure 1 and Figure 4As shown in the figure, in this embodiment, the gas module includes a gas cylinder 6, the gas cylinder 6 is connected to a trachea 4, the other end of the trachea 4 is an annular structure 4-1 and is located at the top of the split cavity crucible 13, and a plurality of air holes 4-2 are provided on both the inner and outer sides of the annular structure 4-1.

[0054] During actual use, in this embodiment, the trachea 4 is used to connect the gas cylinder 6 and the melting and infiltration module, which is used to evacuate the air in the split cavity crucible 13 before forming and provide an atmosphere during the forming process; by designing the end of the trachea 4 as an annular structure 4-1 and providing air holes 4-2, an atmosphere micro-region can be formed at the top of the split cavity crucible 13; preferably, the gas in the gas cylinder 6 in this embodiment is argon, and the density of argon is greater than that of air, which can sink to discharge the air in the split cavity crucible 13, and the ultrasonic vibration effect is better in an argon atmosphere.

[0055] Furthermore, as Figure 3 shown in the figure, in this embodiment, a fine sand layer 17 is laid in the lower cavity 13-2.

[0056] During actual use, in this embodiment, by laying a fine sand layer 17 at the bottom of the lower cavity 13-2, during the infiltration process, part of the gas in the porous carbon fiber preform 16 driven out by the downward flow of the magnesium alloy melt is driven to the bottom of the porous carbon fiber preform 16 and enters the fine sand layer 17, avoiding the accumulation of gas at the bottom end of the porous carbon fiber preform 16 and ensuring the infiltration effect; preferably, the fine sand layer 17 in this embodiment is placed in an open container, which is convenient for placing the porous carbon fiber preform 16 on the top of the fine sand layer 17.

[0057] Furthermore, as Figure 3 shown in the figure, in this embodiment, the choke plug 15 is wedge-shaped, and the material of the choke plug 15 is graphite.

[0058] During actual use, in this embodiment, by setting the choke plug 15 as wedge-shaped, it is convenient for the ultrasonic device to press down the choke plug 15 to connect the upper cavity 13-1 and the lower cavity 13-2; by using a choke plug 15 made of graphite with a small density, when it stays on the top of the porous carbon fiber preform 16 after being pressed down by the ultrasonic device, the contact force with the porous carbon fiber preform 16 is extremely small. Combined with the porous skeleton structure of the porous carbon fiber preform 16, the two cannot fit tightly, and the magnesium alloy melt can flow from other holes to the area below the projection surface of the choke plug 15, ensuring uniform distribution of the magnesium alloy in the porous carbon fiber preform 16. Preferably, the split cavity crucible 13 in this embodiment is in a hourglass shape, which is used to reduce the volume of the choke plug 15 and the contact area between the choke plug 15 and the porous carbon fiber preform 16.

[0059] Embodiment 2

[0060] This embodiment uses the one-piece forming device in Embodiment 1 to prepare C sf / Mg composite material, comprising the following steps:

[0061] Step 1: Place the porous carbon fiber preform 16 with a fiber volume fraction of 20% on top of the fine sand layer 17, put the divided cavity crucible 13 into the melting equipment 5, open the gas cylinder 6 to form an argon micro-region protection on top of the divided cavity crucible 13, then insert a choke plug 15 at the interfaces of the upper cavity 13-1 and the lower cavity 13-2, place the AZ91D magnesium alloy block 14 in the upper cavity 13-1, and turn on the melting equipment 5 for melting to obtain a magnesium alloy melt;

[0062] Step 2: Control the electric cylinder 11 to descend through the servo controller 10, drive the ultrasonic rod 2 to descend into the upper cavity 13-1, and perform ultrasonic vibration on the magnesium alloy melt obtained in Step 1; subsequently, continue to move the ultrasonic rod 2 downward and press down the choke plug 15, then stay at a position 1 cm to 2 cm above the top of the porous carbon fiber preform 16 to maintain ultrasonic vibration. The magnesium alloy melt flows towards the porous carbon fiber preform 16 and infiltrates into the fiber preform under the dual action of gravity and ultrasonic vibration;

[0063] Step 3: After the infiltration in Step 2 is completed, turn off the heating function of the melting equipment 5, and keep the ultrasonic rod 2 continuously performing ultrasonic vibration until the magnesium alloy melt is completely solidified to obtain the C sf / Mg composite material.

[0064] Perform microscopic analysis on the top and internal regions of the C sf / Mg composite material obtained in this embodiment, as Figure 5 shown. There is no white precipitation layer on the top of this C sf / Mg composite material; perform microscopic analysis on the top and internal regions of the composite material prepared by the pressure infiltration method using the AZ91D magnesium alloy block 14 and the porous carbon fiber preform 16 with a fiber volume fraction of 20% as raw materials, as Figure 8 shown. When prepared by the pressure infiltration method, the second phase in the magnesium alloy melt is prone to grow, and after growing up, it cannot penetrate through the porous preform and will accumulate on the top of the porous carbon fiber preform 16. At the same time, component segregation will occur during pressure infiltration, forming a white precipitation phase (the compound Al8Mn5 formed by Al and Mn) on the top. By comparing Figure 5 and Figure 8 it can be seen that by using ultrasonic vibration + gravity infiltration in this embodiment, dendrites can be broken and dendrite growth can be hindered, avoiding component segregation and improving the uniformity of the C sf / Mg composite material.

[0065] As Figure 6 and Figure 7 shown, magnify and observe the top and internal regions of the C sf / Mg composite material again; as Figure 9 and Figure 10As shown, the top and internal regions of the composite material prepared by the pressure infiltration method were observed again at a larger magnification. By Figure 6 comparing with Figure 9 , in this embodiment, there is no second-phase agglomeration and precipitation phase at the top of the prepared C sf / Mg composite material. By Figure 7 comparing with Figure 10 , no pore defects were found inside the prepared C sf / Mg composite material in this embodiment; it shows that the preparation method of this embodiment can avoid the occurrence of second-phase agglomeration and precipitation phase at the top of the C sf / Mg composite material and reduce the internal pore defects.

[0066] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent structural transformations made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. An integrated forming device for C sf / Mg composite materials, characterized in that It includes a melting and infiltration module, a movable ultrasonic device extending into the melting and infiltration module, and a gas module communicating with the melting and infiltration module. The melting and infiltration module includes a melting device (5) and a divided-chamber crucible (13) located inside the melting device (5). A flow-blocking plug (15) is provided at the interface between the upper chamber (13-1) and the lower chamber (13-2) of the divided-chamber crucible (13).

2. An integrated forming device for a C sf / Mg composite material, characterized in that The ultrasonic device is an ultrasonic rod (2). A bracket (3) is fixedly connected to the ultrasonic rod (2), and a power mechanism for driving the movement of the bracket (3) is installed on the bracket (3).

3. An integrated forming device for a C sf / Mg composite material, characterized in that The power mechanism includes an electric cylinder (11) connected to the bracket (3), a servo motor (8) connected to the electric cylinder (11), and a servo controller (10) electrically connected to the servo motor (8).

4. An integrated forming device for a C sf / Mg composite material, characterized in that A limiting mechanism is provided on the ultrasonic rod (2). The limiting mechanism includes a moving guide sleeve (1), a guide sleeve bracket (12) fixedly connected to the moving guide sleeve (1), and a moving frame (9) fixedly connected to the guide sleeve bracket (12).

5. An integrated forming device for a C sf / Mg composite material, characterized in that A support platform (7) is provided at the bottom end of the melting device (5).

6. An integrated forming device for a C sf / Mg composite material, characterized in that The gas module includes a gas cylinder (6). The gas cylinder (6) is communicated with a gas pipe (4). The other end of the gas pipe (4) is in a ring structure (4-1) and is located at the top end of the divided-chamber crucible (13). A plurality of air holes (4-2) are provided on both the inner and outer sides of the ring structure (4-1).

7. An integrated forming device for a C sf / Mg composite material, characterized in that A fine sand layer (17) is laid in the lower chamber (13-2).

8. An integrated forming device for a C sf / Mg composite material, characterized in that The flow-blocking plug (15) is wedge-shaped, and the material of the flow-blocking plug (15) is graphite.

9. A C sf / Mg composite material one-piece forming method, characterized in that, Using the one-piece forming device according to any one of claims 1 to 8, the one-piece forming method includes the following steps: Step 1: Place the porous carbon fiber preform (16) in the lower chamber (13-2) of the divided-chamber crucible (13). Start the gas module and place the magnesium alloy block (14) in the upper chamber (13-1) of the divided-chamber crucible (13). Then start the melting device (5) to melt the magnesium alloy (14) to obtain a magnesium alloy melt. Step 2: Move the ultrasonic device into the upper chamber (13-1), perform ultrasonic vibration on the magnesium alloy melt obtained in Step 1. Then move the ultrasonic device downward and press down the flow-blocking plug (15) to connect the upper chamber (13-1) and the lower chamber (13-2). The ultrasonic device stays above the porous carbon fiber preform (16) to perform ultrasonic vibration, and the magnesium alloy melt infiltrates into the porous carbon fiber preform (16). Step 3: After the infiltration in Step 2 is completed, turn off the heating function of the smelting equipment (5), and the ultrasonic equipment continues to vibrate ultrasonically until the magnesium alloy melt solidifies to obtain the C sf / Mg composite material.

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