Method and device for improving stability of tackifying particles in foamed aluminum by adopting composite magnetic field
By using composite magnetic field technology during the preparation of foam aluminum, the deposition of tacky particles at the gas-liquid interface is controlled, and the problem of insufficient binding ability of tacky particles at the gas-liquid interface is solved, which significantly improves the stability of foam aluminum.
Patent Information
- Application Number
- CN202411838813.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-03-07
AI Technical Summary
During the preparation of aluminum foam, the viscosity-enhancing particles are not hydrophobic and have weak binding ability with the gas-liquid interface of aluminum foam, which makes it difficult to deposit on the gas-liquid interface and easily flow out of the melt with gravity drainage, reducing the effect of adding sticky particles.
The composite magnetic field technology is adopted to control the movement behavior of the viscosity-enhancing particles in the melt through the combined action of the traveling magnetic field and the rotating magnetic field, so that they are deposited to the gas-liquid interface, thereby improving the stability of the viscosity-enhancing particles.
The composite magnetic field technology significantly improves the stability of the viscosity-enhancing particles in the foam aluminum, prevents them from flowing out, and enhances the overall stability of the foam aluminum, while not affecting the pore structure inside the foam aluminum.
Smart Images
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Figure HDA0005187455470000012
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of foam aluminum preparation, and in particular relates to a method and a device for improving the stability of viscosity-increasing particles in foam aluminum by using a composite magnetic field. Background Art
[0002] When preparing aluminum foam by melt foaming method, it is usually necessary to add viscosity-enhancing particles to improve the stability of aluminum foam. At present, there are two main ways to add viscosity-enhancing particles. One is external addition, such as adding SiC, fly ash and other particles directly to the melt; the other method is to add alloy elements such as magnesium and calcium to react with aluminum through in-situ reaction to generate viscosity-enhancing particles inside the melt. The viscosity-enhancing particles can aggregate into agglomerates in the aluminum foam channel, slow down the drainage of the foam, and increase the viscosity of the melt; at the same time, the particles are deposited on the gas-liquid interface, which can change the curvature of the gas-liquid interface, reduce the suction force on the PB channel (the liquid film between two adjacent foam cells is called a foam film, and three foam liquid films form a Plateau boundary, that is, a PB channel), and improve the stability of the foam. However, during the preparation process, the viscosity-enhancing particles are not hydrophobic enough, and their ability to bind to the gas-liquid interface of aluminum foam is weak. They are not easy to deposit on the gas-liquid interface, and they will flow out of the melt with the gravity drainage, reducing the effect of adding viscosity-enhancing particles. Summary of the invention
[0003] In view of the above problems, the present invention provides a method for improving the stability of viscosity-enhancing particles in foamed aluminum by using a composite magnetic field and a device for implementing the method.
[0004] The method of improving the stability of viscosity-enhancing particles in foamed aluminum by using a composite magnetic field according to the present invention comprises the following contents:
[0005] The foaming precursor containing viscosity-increasing particles is adjusted to 650° C. to 690° C., an inert gas is introduced, and TiH2 powder is added to obtain a melt foaming system; while adding TiH2, the melt foaming system is placed in a composite magnetic field environment of a traveling wave magnetic field and a rotating magnetic field and stirred to perform a foaming reaction; after the reaction is completed, foamed aluminum is obtained.
[0006] The magnetic field intensity of the traveling wave magnetic field can be achieved by adjusting the current. The coil bundle that generates the traveling wave magnetic field is located outside the melt foaming system. The coil bundle consists of six groups of circular coil bundles that are parallel to each other. Each coil bundle is equidistantly distributed. Each coil bundle is wrapped with an iron core to play a magnetic field gathering role. Each coil bundle has 60 turns of coils. The coil bundle is fed by a three-phase current, the phase difference between adjacent coil bundles is 60°, the current intensity is 60A to 75A, and the frequency is 15Hz to 20Hz.
[0007] The magnetic field strength of the rotating magnetic field can be achieved by adjusting the current. The coil bundle that generates the rotating magnetic field is located outside the traveling wave magnetic field coil bundle. Six rectangular salient poles of equal size are evenly distributed on the inner side of the cylindrical shell. A group of coil bundles of the same specifications is wound on each salient pole. The winding direction of the coil bundle is perpendicular to the winding direction of the coil bundle of the traveling wave magnetic field generating device. Each group of coil bundles has 70 turns of coils, and three-phase alternating current with a phase difference of 60° is passed through adjacent rectangular coil bundles. The current intensity is 55A~65A and the frequency is 15Hz~20Hz.
[0008] The sticking particles are exogenous particles or endogenous particles; when they are exogenous particles, they include at least one of SiC, Al2O3, fly ash, etc., and the sticking particles are added to aluminum melt (pure aluminum melt or aluminum alloy melt) and mixed evenly to obtain a foaming precursor containing sticking particles; when they are endogenous particles, the sticking particles are obtained by in-situ reaction, that is, alloy elements such as magnesium and calcium are added to the aluminum melt and reacted with aluminum, and sticking particles (such as MgAl2O4 particles) are generated inside the melt to obtain a foaming precursor containing sticking particles.
[0009] The mass percentage concentration of the viscosity-increasing particles in the melt foaming system is 1.5% to 2.5%, the mass percentage concentration of TiH2 is 1% to 2.5%, and the rest is aluminum melt;
[0010] The foaming reaction refers to the melt foaming system being stirred for 2 to 4 minutes in a composite magnetic field environment of a traveling magnetic field and a rotating magnetic field to mix evenly, and then being kept warm for 4 to 6 minutes to allow the melt (foaming precursor) to fully react with TiH2.
[0011] The above method of using a composite magnetic field to improve the stability of viscosity-increasing particles in foamed aluminum is achieved by the following device:
[0012] The device comprises a heating component, a travelling wave magnetic field generating device is arranged on the periphery of the heating component, and a rotating magnetic field generating device is arranged on the periphery of the travelling wave magnetic field generating device; a crucible is placed inside the heating component; an openable baffle is arranged on the top of the heating component, and a feed port, a stirring device inlet and a vent are arranged on the baffle;
[0013] The traveling wave magnetic field generating device is composed of six groups of circular coil bundles parallel to each other, the coil bundles are equidistantly distributed, each group of coil bundles is wrapped with an iron core, and each group of coil bundles has 60 turns of coils;
[0014] The rotating magnetic field generating device adopts a concentrated coil winding method, and six rectangular salient poles of equal size are evenly distributed on the inner side of the cylindrical shell. A group of coil bundles of the same specifications are wound on each salient pole. The winding direction of the coil bundle is perpendicular to the winding direction of the coil bundle of the traveling wave magnetic field generating device. Each group of coil bundles has 70 turns of coils.
[0015] The specific method of using the above device to realize a composite magnetic field to improve the stability of the viscosity-increasing particles in the foamed aluminum is as follows:
[0016] S1 puts aluminum material into a crucible, puts the crucible into a heating component, uses the heating component to heat the aluminum material to 810°C to 850°C, and obtains a melt after melting. Add viscosity-enhancing particles or alloy elements (such as magnesium powder) to the melt through a feed inlet, inserts a stirring device through an inlet of a stirring device provided on a baffle plate, and fully stirs the melt to obtain a foaming precursor.
[0017] S2 uses a heating component to adjust the temperature of the foaming precursor to 650°C~690°C, inputs an inert gas through the vent, places the foaming precursor under inert gas protection, adds TiH2 powder through the feed port, and stirs for 2min~4min to obtain a melt foaming system; while adding TiH2, a traveling wave magnetic field generating device passes an alternating current with a phase difference of 60°, a current intensity of 60A~75A, and a frequency of 15Hz~20Hz to generate a traveling wave magnetic field; a rotating magnetic field generating device passes an alternating current with a phase difference of 60°, a current intensity of 55A~65A, and a frequency of 15Hz~20Hz to generate a rotating magnetic field; after the melt foaming system is evenly mixed, keep warm for 4min~6min to allow the foaming precursor and TiH2 to fully react in the composite magnetic field;
[0018] After the reaction is completed, the alternating current of the traveling wave magnetic field generating device and the rotating magnetic field generating device is turned off to obtain foamed aluminum with good stability.
[0019] During the foaming process, the present invention applies a rotating magnetic field and a traveling magnetic field, so that the foaming is carried out in a magnetic field environment, generates an induced current in the melt, controls the movement behavior of the tackifying particles in the melt, and increases the stability of the tackifying particles in the foamed aluminum. The flow field is rotated under the action of the rotating magnetic field, and the electromagnetic centrifugal force generated causes the tackifying particles to be deposited on the gas-liquid interface; the traveling magnetic field interacts with the induced current in the foamed aluminum, and the fluid generates a secondary circulation to drive the tackifying particles to move, so that the tackifying particles in the center of the foamed aluminum channel flow and float under the action of the flow field, and the tackifying particles near the gas-liquid interface (PB channel wall) float due to the action of the electromagnetic extrusion force; under the joint action of the two, the tackifying particles are deposited on the upper part of the foamed aluminum channel, preventing the particles from being discharged from the foamed aluminum due to the fluidity of the gas-liquid interface and the action of gravity, thereby enhancing the stability of the foamed aluminum; the intensity of the applied composite magnetic field is controlled within a certain range, and does not affect the pore structure inside the foamed aluminum. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 A schematic diagram of a device for preparing foamed aluminum using a composite magnetic field according to the present invention;
[0021] Among them, there are crucible-1, heating component-2, rotating magnetic field generating device-3, traveling wave magnetic field generating device-4, stirring device-5, feed port-6, valve-7, vent-8, baffle-9.
[0022] Figure 2 This is a schematic diagram of the distribution of viscosity-enhancing particles in the liquid film when preparing foamed aluminum; the left side shows the situation where no magnetic field is added during the preparation process, and the right side shows the situation where the composite magnetic field of the present invention is added during the preparation process. DETAILED DESCRIPTION
[0023] The device for preparing foamed aluminum using a composite magnetic field in the embodiment is as follows Figure 1 As shown, the coil bundles in the traveling wave magnetic field generating device and the rotating magnetic field generating device are both wound by concentrated coils and connected in a star-shaped connection, and the magnetic field strength varies with the position. The melt includes pure aluminum and aluminum alloy (such as Al-9wt% Si alloy, etc.). The particle size of the TiH2 powder used in the present invention is 40μm to 55μm; the particle size of the viscosity-enhancing particles is 20μm to 60μm, and the mass specific gravity in the melt foaming system is 1.5% to 2.5%. In Examples 1 and 2, SiC particles and Al2O3 particles are taken as examples, and in Example 3, magnesium powder is used to synthesize MgAl2O4 particles by in-situ reaction in aluminum melt as an example. The main purpose of the present invention is to control the flow form of viscosity-enhancing particles in the PB channel during foamed aluminum foaming by a composite magnetic field. There is no special requirement for the stirring method, as long as it meets the requirements of the melt foaming process and the materials are mixed evenly.
[0024] Example 1
[0025] S1: pure aluminum (95.5 wt%) is placed in a crucible 1, heated to 810°C by a heating component 2 to obtain an aluminum melt, and the temperature is kept constant. The baffle 9 is closed, the valve 7 is opened, SiC particles (2 wt%) are added to the aluminum melt from the feed port 6, and the mixture is fully stirred by a stirring device 5 to obtain a foaming precursor.
[0026] S2 uses the heating component 2 to heat the above foaming precursor to 650°C, inputs inert gas protection through the vent 8, adds TiH2 powder (2.5wt%) through the feed port 6, and the stirring device 5 continues to stir (800rpm, 150s) to obtain a melt foaming system. While adding TiH2, the traveling wave magnetic field generating device 4 is connected to an alternating current with a phase difference of 60°, a current intensity of 60A, and a frequency of 15Hz; the rotating magnetic field generating device 3 is connected to an alternating current with a phase difference of 60°, a current intensity of 55A, and a frequency of 15Hz; after the melt foaming system is evenly mixed, it is kept warm for 4 minutes to perform a sufficient foaming reaction.
[0027] After the foaming reaction is completed, the alternating current of the rotating magnetic field generating device 3 and the traveling wave magnetic field generating device 4 is turned off, and after cooling, foamed aluminum with good stability is obtained.
[0028] Example 2
[0029] S1: pure aluminum (97 wt%) is placed in a crucible 1, heated to 830°C by a heating component 2 to obtain an aluminum melt, and the temperature is kept constant. The baffle 9 is closed, the valve 7 is opened, Al2O3 particles (1.5 wt%) are added to the aluminum melt from the feed port 6, and the mixture is fully stirred by a stirring device 5 to obtain a foaming precursor.
[0030] S2 uses the heating component 2 to heat the above foaming precursor to 670°C, inputs inert gas protection through the vent 8, adds TiH2 powder (1.5wt%) through the feed port 6, and the stirring device 5 continues to stir (900rpm, 135s) to obtain a melt foaming system. While adding TiH2, the traveling wave magnetic field generating device 4 is connected to an alternating current with a phase difference of 60°, a current intensity of 75A, and a frequency of 20Hz; the rotating magnetic field generating device 3 is connected to an alternating current with a phase difference of 60°, a current intensity of 65A, and a frequency of 20Hz; after the melt foaming system is evenly mixed, it is kept warm for 5 minutes to perform a sufficient foaming reaction.
[0031] After the foaming reaction is completed, the alternating current of the rotating magnetic field generating device 3 and the traveling wave magnetic field generating device 4 is turned off, and after cooling, foamed aluminum with good stability is obtained.
[0032] Example 3
[0033] S1: Al-9wt%Si alloy (93.5wt%) is placed in a crucible 1, heated to 815°C by a heating component 2 to obtain an aluminum melt, and the temperature is kept constant. The baffle 9 is closed, the valve 7 is opened, Mg powder (5wt%) is added to the melt from the feed port 6, and the melt is stirred (700rpm) by a stirring device 5, and kept at 830°C for 9 hours to obtain a foaming precursor containing MgAl2O4 viscosity-increasing particles.
[0034] S2 uses the heating component 2 to heat the above foaming precursor to 650°C, and the vent 8 inputs inert gas protection. TiH2 powder (1.5wt%) is added through the feed port 6, and the stirring device 5 continues to stir (1100rpm, 120s) to obtain a melt foaming system. At the same time, the traveling wave magnetic field generating device 4 is connected to an alternating current with a phase difference of 60°, a current intensity of 65A, and a frequency of 18Hz; the rotating magnetic field generating device 3 is connected to an alternating current with a phase difference of 60°, a current intensity of 60A, and a frequency of 18Hz. After the melt foaming system is evenly mixed, keep it warm for 6 minutes to carry out a sufficient foaming reaction.
[0035] After the foaming reaction is completed, the AC power of the rotating magnetic field generator 3 and the traveling wave magnetic field generator 4 is turned off, the heater is turned off, and the foam is cooled naturally. At this time, the generated MgAl2O4 viscosity-enhancing particles are densely embedded in the oxide skin at the gas-solid interface, slowing down the melt flow in the film, and obtaining foamed aluminum with good stability.
[0036] When the aluminum foam is prepared without adding a magnetic field, the viscosity-enhancing particles are dispersed in the liquid film, as shown in the schematic diagram. Figure 2 When the method of the present invention is used to prepare aluminum foam, a composite magnetic field is formed after the power is turned on. The magnetic field strength is controlled by adjusting the current, so that the viscosity-enhancing particles are more easily adsorbed on the gas-liquid interface and evenly distributed. The schematic diagram is shown as follows: Figure 2 As shown on the right, the outflow loss of the viscosity-enhancing particles is slowed down.
Claims
1. A method for improving the stability of viscosity-enhancing particles in aluminum foam by using a composite magnetic field, characterized in that: Includes the following: An inert gas is introduced into a foaming precursor containing viscosity-increasing particles, and TiH2 powder is added to obtain a melt foaming system; while adding TiH2, the melt foaming system is placed in a composite magnetic field environment of a traveling wave magnetic field and a rotating magnetic field to perform a foaming reaction, and foamed aluminum is obtained after the reaction is completed; The traveling wave magnetic field is formed by three-phase current feeding, the current intensity is 60A to 75A, and the frequency is 15Hz to 20Hz; The rotating magnetic field is formed by three-phase current feeding, the current intensity is 55A-65A, and the frequency is 15Hz-20Hz.
2. The method for improving the stability of viscosity-enhancing particles in aluminum foam by using a composite magnetic field according to claim 1, characterized in that: The mass percentage concentration of the viscosity-increasing particles in the melt foaming system is 1.5% to 2.5%, the mass percentage concentration of TiH2 is 1% to 2.5%, and the rest is aluminum melt.
3. The method for improving the stability of viscosity-enhancing particles in foamed aluminum by using a composite magnetic field according to claim 1, characterized in that: The viscosity-enhancing particles are exogenous particles or endogenous particles; when they are exogenous particles, they include at least one of SiC, Al2O3, and fly ash. The exogenous particles are added to the aluminum melt and mixed evenly to obtain a foaming precursor containing the viscosity-enhancing particles; when they are endogenous particles, the viscosity-enhancing particles are obtained by in-situ reaction, that is, alloy elements are added to the aluminum melt to react with aluminum, viscosity-enhancing particles are generated inside the melt, and a foaming precursor containing the viscosity-enhancing particles is obtained.
4. The method for improving the stability of viscosity-enhancing particles in aluminum foam by using a composite magnetic field according to claim 1, characterized in that: The traveling wave magnetic field is generated by several groups of coil bundles parallel to each other, and three-phase alternating current with a phase difference of 60° is passed through adjacent coil bundles; the rotating magnetic field is generated by several groups of coil bundles, and the winding direction of the coil bundle is perpendicular to the winding direction of the coil bundle generating the traveling wave magnetic field, and three-phase alternating current with a phase difference of 60° is passed through adjacent coil bundles.
5. The device for improving the stability of viscosity-enhancing particles in foamed aluminum by using a composite magnetic field according to any one of claims 1 to 4, characterized in that: Includes the following: The device comprises a heating component, a travelling wave magnetic field generating device is arranged on the periphery of the heating component, and a rotating magnetic field generating device is arranged on the periphery of the travelling wave magnetic field generating device; a crucible is placed inside the heating component; an openable baffle is arranged on the top of the heating component, and a feed port, a stirring device inlet and a vent are arranged on the baffle; The traveling wave magnetic field generating device is composed of a plurality of groups of circular coil bundles parallel to each other, the coil bundles are equidistantly distributed, each group of coil bundles is wrapped with an iron core, and each group of coil bundles has a plurality of coil turns; A number of rectangular salient poles of the same size are evenly distributed on the inner side of the cylindrical shell in the rotating magnetic field generating device, and a group of coil bundles of the same specifications are wound around each salient pole. The winding direction of the coil bundle is perpendicular to the winding direction of the coil bundle of the traveling wave magnetic field generating device, and each group of coil bundles has several turns of coils.
6. The method for using the device for improving the stability of viscosity-enhancing particles in foamed aluminum by using a composite magnetic field as claimed in claim 5, characterized in that: Includes the following: S1: putting aluminum material into a crucible, putting the crucible into a heating component, heating the aluminum material to 810°C to 850°C by the heating component, and obtaining a melt after melting, adding viscosity-increasing particles or alloy elements to the melt through a feed inlet, inserting a stirring device through an inlet of a stirring device provided on a baffle plate to fully stir, and obtaining a foaming precursor; S2 uses a heating component to adjust the temperature of the foaming precursor to 650°C~690°C, inputs an inert gas through the vent, places the foaming precursor in the inert gas, adds TiH2 powder through the feed port, and stirs to obtain a melt foaming system; while adding TiH2, a traveling wave magnetic field generating device passes an alternating current with a phase difference of 60°, a current intensity of 60A~75A, and a frequency of 15Hz~20Hz to generate a traveling wave magnetic field; a rotating magnetic field generating device passes an alternating current with a phase difference of 60°, a current intensity of 55A~65A, and a frequency of 15Hz~20Hz to generate a rotating magnetic field; the foaming precursor and TiH2 are fully reacted in the magnetic field; After the reaction is completed, the alternating current of the traveling wave magnetic field generating device and the rotating magnetic field generating device is turned off to obtain foamed aluminum.