Preparation method of high-stability aluminum alloy foam and melt foaming device thereof

Abstract

The invention discloses a preparation method of high-stability aluminum alloy foam and a melt foaming device of the high-stability aluminum alloy foam. The preparation method comprises four processes of melt preparation, foaming agent dispersion, isothermal foaming and solidification cooling, namely heating AlSi12 until the AlSi12 is molten, adding 4wt% of AlCa75, 2wt% of AlMg50 and 10wt% of AlSc2, stirring for 15 minutes, and keeping the temperature at 605 + / -5 DEG C; coating about 1.0 wt% of TiH2 powder with high-purity aluminum foil, preheating the TiH2 powder to about 150 DEG C, adding the TiH2 powder into the prepared melt, then mechanically stirring and dispersing the TiH2 powder for about 5 + / -1 minutes, keeping the temperature at 595 + / -2 DEG C for heat preservation and foaming, and cooling melt foam at the room temperature of 15-25 DEG C; the aluminum alloy melt can generate micron-sized alloy second phases Al4Ca and Al2Si2Ca and nano-sized Al3Sc at the foaming temperature, the purpose of hindering melt foam evolution is achieved by hindering gravity liquid drainage and capillary liquid drainage of melt foam, then the stability of the melt foam is improved, aluminum alloy foam with a uniform pore structure is obtained, and the service life of the aluminum alloy foam is prolonged. The preparation of the high-stability aluminum alloy melt foam is realized; the method is simple in process, low in cost, efficient, environmentally friendly and capable of achieving industrial application.

Description

Technical Field

[0001] The invention relates to the technical field of processing and preparing new foam aluminum materials, and in particular to a preparation method of high-stability aluminum alloy foam and a melt foaming device thereof. Background Art

[0002] With the development of the times and the rapid progress of the economy, the requirements for lightweight metal materials in daily life and industry are getting higher and higher. The "foam"-like porous structure of aluminum alloy foam determines its use in life and industry;

[0003] Aluminum alloy foam is an excellent structural functional material due to its physical properties such as low density, high specific strength, energy absorption, and sound absorption. Closed-cell aluminum alloy foam exhibits good energy absorption performance and higher mechanical damping than aluminum itself. It has been widely used in the production of automotive energy-absorbing blocks, aircraft and ship doors, and other lightweight structural parts that require a certain strength. Aluminum alloy foam also has the characteristics of lightweight, corrosion resistance, and fire resistance, which makes it have a huge market in the fields of building exterior wall decoration and lightweight fireproof panels. However, during the production process, the stability of the melt foam is poor, and the evolution of the pore structure leads to foam collapse and pore wall rupture, resulting in poor product stability, low yield, and difficulty in achieving the expected performance, which are all obstacles to the application of aluminum alloy foam.

[0004] Aiming at the disadvantage of poor stability of aluminum alloy foam, the present invention discloses a method for preparing high-stability aluminum alloy foam to solve the above problem. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing high-stability aluminum alloy foam and a melt foaming device thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a melt foaming device for high-stability aluminum alloy foam, comprising an electric stirrer, an asbestos upper cover, a TC titanium alloy stirring rod, a crucible resistance furnace, a graphite crucible and a crucible support; the graphite crucible is placed inside the electric crucible resistance furnace, the middle of the graphite crucible contains a foaming melt, the crucible support is installed at the bottom of the graphite crucible and supports the graphite crucible, the asbestos upper cover is located at the top opening of the crucible resistance furnace, the electric stirrer is above the asbestos upper cover and is transmission-connected to the TC titanium alloy stirring rod, the TC titanium alloy stirring rod stirs the foaming melt and foams, the asbestos upper cover can slow down heat loss, and a temperature-control thermocouple is provided at the bottom of the crucible resistance furnace; the electric stirrer is installed above the crucible resistance furnace through a support.

[0007] A method for preparing high-stability aluminum alloy foam, comprising: melting different alloys in the following weight proportions at high temperature in the melt foaming device:

[0008] AlSi12: 84 parts;

[0009] AlCa75: 4 parts;

[0010] AlMg50: 2 parts;

[0011] AlSc2: 10 parts;

[0012] Among them, AlSi12 is the main matrix alloy component, AlCa75 is a viscosity enhancer, AlMg50 is a surfactant, and the main function of AlSc2 is micro-alloying; AlCa75, AlMg50 and AlSc2 all need to be coated with high-purity aluminum foil when added to the high-temperature melt to avoid the alloy from deflagration in high-temperature air and causing loss of effective components.

[0013] Preferably, the preparation method specifically comprises the following steps:

[0014] (1) 84 parts of AlSi12 were added into a graphite crucible, and AlSi12 was heated in a crucible resistance furnace until it was melted. Four parts of AlCa75, two parts of AlMg50, and ten parts of AlSc2 were respectively coated with aluminum foil, and then added into the molten AlSi12 melt. The melt was mechanically stirred at 800 r / min with an electric stirrer for 15 minutes, and the melt temperature was maintained within the range of 605±5°C.

[0015] (2) Wrap 1 part of TiH with high purity aluminum foil 2 The powder is preheated to 150±5°C in a drying oven and added to the melt prepared in step (1); then, an electric stirrer is used to mechanically stir and disperse the powder at a speed of 1200 r / min for 5±1 minutes, and the temperature is maintained within the range of 595±2°C;

[0016] (3) Keep the foaming temperature within the range of 595±2℃ and control the foaming time within 8-10 minutes;

[0017] (4) The graphite crucible containing the foamed melt is taken out and the melt foam is allowed to cool at room temperature 15-25°C to obtain aluminum foam with a uniform pore structure.

[0018] Preferably, the TiH 2 The pretreatment process of the powder is: air atmosphere, heat treatment 400℃×20h+470℃×4h.

[0019] Preferably, the TiH 2 The particle size of the powder is 200 mesh.

[0020] Principle of the invention:

[0021] 1. TiH 2 Slow decomposition principle

[0022] In air atmosphere, TiH 2 Heat treatment at 400℃×20h+470℃×4h was performed to make TiH 2 Surface decomposition releases hydrogen and oxidizes to form TiO 2 Achieve the effect of slowing down the foaming time. Figure 1 TiH after heat treatment 2 The isothermal decomposition curve of the powder at a foaming temperature of 595°C shows that the undecomposed stage is longer, which is more conducive to TiH 2 Dispersion of powder in melt.

[0023] 2. Principle of low temperature foaming of melt

[0024] By melting and adjusting the composition of the aluminum alloy foam matrix, an aluminum alloy melt with good fluidity at a relatively low foaming temperature (595°C) is obtained. Figure 2 The viscosity of the aluminum alloy foam matrix at the foaming temperature is shown in the figure. At this temperature, the melt viscosity is low, which is conducive to the formation and growth of the alloy foam.

[0025] 3. Principle of second phase stabilization of melt foam

[0026] By forming a micron-sized alloy second phase Al 4 Ca and Al 2 Si 2 Ca and nano-scale Al 3 Sc can achieve the purpose of stabilizing the foam of aluminum alloy melt. Figure 3 The principle of second phase stabilization of melt foam is described. The second phase hinders the growth of foam and flows along with the evolution of the pore structure of the melt foam. It gathers at the boundaries and nodes to hinder the drainage and merging of the foam, thereby improving the stability of the melt foam.

[0027] Beneficial effects: Compared with the prior art, the beneficial effects of the present invention are:

[0028] The preparation method of high-stability aluminum alloy foam, because the base alloy of the aluminum alloy foam is selectively smelted, can be foamed at a lower temperature to achieve the effect of low-temperature viscosity increase; at the same time, TiH 2 The powder is heat treated in air atmosphere to achieve the effect of slow decomposition, which makes the pore structure of the melt foam evolve slowly and improves stability; finally, at the foaming temperature, a micron-sized alloy second phase Al 4 Ca and Al 2 Si 2 Ca and nano-scale Al 3Sc, by hindering the gravity drainage and capillary drainage of the melt foam, the purpose of hindering the evolution of the melt foam is achieved, and the high stability of the aluminum alloy foam is realized; the present invention has the characteristics of simple process, low cost, high efficiency and environmental protection, and can be realized in large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 TiH after heat treatment 2 Isothermal decomposition curve of the powder at foaming temperature 595℃.

[0030] Figure 2 : The viscosity of the aluminum alloy foam matrix at the foaming temperature.

[0031] Figure 3 Schematic diagram of the principle of second phase stabilization of melt foam.

[0032] Figure 4 Schematic diagram of the structure of the obtained aluminum alloy foam.

[0033] Figure 5 The figure is a flow chart of the preparation process.

[0034] Figure 6 It is a schematic diagram of the structure of the melt foaming device.

[0035] In the attached drawings: 1-electric stirrer, 2-asbestos upper cover, 3-TC4 titanium alloy stirring rod, 4-crucible resistance furnace, 5-graphite crucible, 6-foaming melt, 7-crucible support, 8-temperature control thermocouple. DETAILED DESCRIPTION

[0036] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.

[0038] A melt foaming device for high-stability aluminum alloy foam comprises an electric stirrer 1, an asbestos upper cover 2, a TC4 titanium alloy stirring rod 3, a crucible resistance furnace 4, a graphite crucible 5 and a crucible support 7; the graphite crucible 5 is placed inside the electric crucible resistance furnace 4, a foaming melt 6 is contained in the middle of the graphite crucible 5, the crucible support 7 is installed at the bottom of the graphite crucible 5 and supports the graphite crucible 5, the asbestos upper cover 2 is located at the top opening of the crucible resistance furnace 4, the electric stirrer 1 is above the asbestos upper cover 2 and is transmission-connected to the TC4 titanium alloy stirring rod 3, the TC4 titanium alloy stirring rod 3 stirs the foaming melt 6 and foams, the asbestos upper cover 2 can slow down heat loss, and a temperature-controlling thermocouple 8 is provided at the bottom of the crucible resistance furnace 4; the electric stirrer 1 is installed above the crucible resistance furnace 4 through a support.

[0039] Example 1

[0040] In an embodiment of the present invention, a method for preparing a high-stability aluminum alloy foam specifically comprises the following steps:

[0041] (1) TiH 2 Powder pretreatment

[0042] The commercially available TiH 2 The powder is spread flat on a tray, and the tray is placed in an air atmosphere resistance furnace for heat treatment. The heat treatment process is 400℃×20h+470℃×4h. During the entire heat treatment process, the powder is turned over every 4 hours.

[0043] (2) Melt preparation

[0044] Add 84 parts of AlSi12 into a crucible, heat AlSi12 in a crucible resistance furnace until it is melted, wrap 4 parts of AlCa75, 2 parts of AlMg50 and 10 parts of AlSc2 with aluminum foil, and then add them into the molten AlSi12 melt, use an electric stirrer to mechanically stir the melt at a speed of 800r / min for 15 minutes, and maintain the melt temperature at 605℃.

[0045] (3) TiH 2 Powder dispersion

[0046] The TiH obtained in step 1 2 The powder was coated with about 1 part of high-purity aluminum foil, preheated to 150±5°C in a drying oven, and added to the melt prepared in step (2). Then, an electric stirrer was used to mechanically stir and disperse the mixture at a speed of 1200 r / min for 5 minutes, and the temperature was maintained at 595°C.

[0047] (4) Melt Foaming

[0048] The foaming process was carried out at a temperature of 595°C and the foaming time was controlled within 8 minutes.

[0049] (5) Solidification cooling

[0050] The crucible containing the foamed melt was taken out and the melt foam was cooled at room temperature (25°C) to obtain aluminum foam with uniform pore structure. Figure 4 (a).

[0051] Example 2

[0052] Compared with Example 1, this embodiment changes TiH 2 The powder size and processing process, the detailed steps are as follows:

[0053] (1) TiH 2 Powder pretreatment

[0054] The commercially available TiH 2 The powder is spread flat on a tray, and the tray is placed in a resistance furnace in an air atmosphere for heat treatment. The heat treatment process is 400℃×20h+455℃×4h. During the entire heat treatment process, the powder is turned over every 4 hours.

[0055] (2) Melt preparation

[0056] Add 84 parts of AlSi12 into a crucible, heat AlSi12 in a crucible resistance furnace until it is melted, wrap 4 parts of AlCa75, 2 parts of AlMg50 and 10 parts of AlSc2 with aluminum foil, and then add them into the molten AlSi12 melt, use an electric stirrer to mechanically stir the melt at a speed of 800r / min for 15 minutes, and maintain the melt temperature at 605℃.

[0057] (3) TiH 2 Powder dispersion

[0058] The TiH obtained in step 1 2 The powder was coated with about 1 part of high-purity aluminum foil, preheated to 150±5°C in a drying oven, and added to the melt prepared in step (2). Then, an electric stirrer was used to mechanically stir and disperse the mixture at a speed of 1200 r / min for 5 minutes, and the temperature was maintained at 595°C.

[0059] (4) Melt Foaming

[0060] The foaming process was carried out at a temperature of 595°C and the foaming time was controlled within 8 minutes.

[0061] (5) Solidification cooling

[0062] The crucible containing the foamed melt was taken out, and the melt foam was allowed to cool at room temperature 25°C to obtain aluminum foam with a uniform pore structure.

[0063] Example 3

[0064] Compared with Example 1, this embodiment changes the foaming time, and the detailed steps are as follows:

[0065] (1) TiH 2 Powder pretreatment

[0066] The commercially available TiH 2 The powder is spread flat on a tray, and the tray is placed in an air atmosphere resistance furnace for heat treatment. The heat treatment process is 400℃×20h+470℃×4h. During the entire heat treatment process, the powder is turned over every 4 hours.

[0067] (2) Melt preparation

[0068] Add 84 parts of AlSi12 into a crucible, heat AlSi12 in a crucible resistance furnace until it is melted, wrap 4 parts of AlCa75, 2 parts of AlMg50 and 10 parts of AlSc2 with aluminum foil, and then add them into the molten AlSi12 melt, use an electric stirrer to mechanically stir the melt at a speed of 800r / min for 15 minutes, and maintain the melt temperature at 605℃.

[0069] (3) TiH 2 Powder dispersion

[0070] The TiH2 powder obtained in step 1 was coated with high-purity aluminum foil, preheated to 150±5°C in a drying oven, and added to the melt prepared in step (2). Then, an electric stirrer was used to mechanically stir and disperse the powder at a speed of 1200 r / min for 5 minutes, and the temperature was maintained at 595°C.

[0071] (4) Melt Foaming

[0072] The foaming process was carried out at a temperature of 595°C and the foaming time was controlled within 10 minutes.

[0073] (5) Solidification cooling

[0074] The crucible containing the foamed melt was taken out and the melt foam was cooled at room temperature (25°C) to obtain aluminum foam with uniform pore structure. Figure 4 (b).

[0075] Example 4

[0076] Compared with Example 1, this example changes the electric stirrer in melt preparation and TiH 2 The speed and time of dispersion are as follows:

[0077] (1) TiH 2 Powder pretreatment

[0078] The commercially available TiH2 The powder is spread flat on a tray, and the tray is placed in an air atmosphere resistance furnace for heat treatment. The heat treatment process is 400℃×20h+470℃×4h. During the entire heat treatment process, the powder is turned over every 4 hours.

[0079] (2) Melt preparation

[0080] Add 84 parts of AlSi12 into a crucible, heat AlSi12 in a crucible resistance furnace until it is melted, wrap 4 parts of AlCa75, 2 parts of AlMg50 and 10 parts of AlSc2 with aluminum foil, and then add them into the molten AlSi12 melt. Use an electric stirrer to mechanically stir the melt at a speed of 1000r / min for 12 minutes, and maintain the melt temperature at 605℃.

[0081] (3) TiH 2 Powder dispersion

[0082] The TiH obtained in step 1 2 The powder was coated with about 1 part of high-purity aluminum foil, preheated to 150±5°C in a drying oven, and added to the melt prepared in step (2). Then, an electric stirrer was used to mechanically stir and disperse the mixture at a speed of 1500 r / min for 4 minutes, and the temperature was maintained at 595°C.

[0083] (4) Melt Foaming

[0084] The foaming process was carried out at a temperature of 595°C and the foaming time was controlled within 10 minutes.

[0085] (5) Solidification cooling

[0086] The crucible containing the foamed melt was taken out, and the melt foam was allowed to cool at room temperature 25°C to obtain aluminum foam with a uniform pore structure.

[0087] The process flow of all embodiments adopts Figure 5 The process flow is shown.

[0088] In the present invention, since the base alloy of the aluminum alloy foam is selectively smelted, it can be foamed at a relatively low temperature to achieve the effect of low-temperature viscosity enhancement; at the same time, TiH 2 The powder is heat treated in air atmosphere to achieve the effect of slow decomposition, which makes the pore structure of the melt foam evolve slowly and improves stability; finally, at the foaming temperature, a micron-sized alloy second phase Al 4 Ca and Al 2 Si 2 Ca and nano-scale Al 3Sc, by hindering the gravity drainage and capillary drainage of the melt foam, the purpose of hindering the evolution of the melt foam is achieved, and the high stability of the aluminum alloy foam is realized; the present invention has the characteristics of simple process, low cost, high efficiency and environmental protection, and can be realized in large-scale industrial application.

[0089] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0090] In the description of the present invention, it is necessary to understand that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

Claims

1. A melt foaming device for high-stability aluminum alloy foam, characterized in that: The invention comprises an electric stirrer (1), an asbestos upper cover (2), a TC4 titanium alloy stirring rod (3), a crucible resistance furnace (4), a graphite crucible (5) and a crucible support (7); the graphite crucible (5) is placed inside the electric crucible resistance furnace (4); a foaming melt (6) is contained in the middle of the graphite crucible (5); the crucible support (7) is installed at the bottom of the graphite crucible (5) and supports the graphite crucible (5); the asbestos upper cover (2) is located at the top opening of the crucible resistance furnace (4); the electric stirrer (1) is above the asbestos upper cover (2) and is connected to the TC4 titanium alloy stirring rod (3) by transmission; the TC4 titanium alloy stirring rod (3) stirs the foaming melt (6) and foams; the asbestos upper cover (2) can slow down heat loss; a temperature-controlling thermocouple (8) is provided at the bottom of the crucible resistance furnace (4); the electric stirrer (1) is installed above the crucible resistance furnace (4) through a support.

2. A method for preparing a high-stability aluminum alloy foam, characterized in that: The following alloys in different weight proportions are melted at high temperature in the melt foaming device: AlSi12: 84 parts; AlCa75: 4 parts; AlMg50: 2 parts; AlSc2: 10 parts; Among them, AlSi12 is the main matrix alloy component, AlCa75 is a viscosity enhancer, AlMg50 is a surfactant, and the main function of AlSc2 is micro-alloying; AlCa75, AlMg50 and AlSc2 all need to be coated with high-purity aluminum foil when added to the high-temperature melt to avoid the alloy from deflagration in high-temperature air and causing loss of effective components.

3. The method for preparing a high-stability aluminum alloy foam according to claim 2, characterized in that: The specific steps include: (1) 84 parts of AlSi12 were added into a graphite crucible, and AlSi12 was heated in a crucible resistance furnace until it was melted. Four parts of AlCa75, two parts of AlMg50, and ten parts of AlSc2 were respectively coated with aluminum foil, and then added into the molten AlSi12 melt. The melt was mechanically stirred at 800 r / min with an electric stirrer for 15 minutes, and the melt temperature was maintained within the range of 605±5°C. (2) Coating 1 part of TiH2 powder with high-purity aluminum foil and preheating it in a drying oven to 150±5°C, and adding it to the melt prepared in step (1); then using an electric stirrer to mechanically stir and disperse at a speed of 1200r / min for 5±1 minutes, and keeping the temperature within the range of 595±2°C; (3) Keep the foaming temperature within the range of 595±2℃ and control the foaming time within 8-10 minutes; (4) The graphite crucible containing the foamed melt is taken out and the melt foam is allowed to cool at room temperature 15-25°C to obtain aluminum foam with a uniform pore structure.

4. The method for preparing a high-stability aluminum alloy foam according to claim 2, characterized in that: The pretreatment process of the TiH2 powder is: air atmosphere, heat treatment at 400°C×20h+470°C×4h.

5. The method for preparing a high-stability aluminum alloy foam according to claim 2, characterized in that: The particle size of the TiH2 powder is 200 mesh.

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