WO2021035813A1

WO2021035813A1 - Device and method for preparing foamed aluminum material by means of air blowing

Info

Publication number: WO2021035813A1
Application number: PCT/CN2019/105633
Authority: WO
Inventors: 耿佃桥; 吴世同; 祖国胤
Original assignee: 东北大学
Priority date: 2019-08-29
Filing date: 2019-09-12
Publication date: 2021-03-04
Also published as: CN110438361B; CN110438361A

Abstract

Disclosed are a device and a method for preparing a foamed aluminum material by means of air blowing. The device comprises a reaction container (7), air blowing pipes (4) and an air chamber (3), wherein a stirring paddle (10) is arranged inside the reaction container (7); a plurality of air blowing pipes (4) penetrate a bottom plate of the reaction container (7) and are fixed on the bottom plate; an air blowing pipe head (6) is arranged at the top end of the air blowing pipe (4), the bottom end of each air blowing pipe (4) is in communication with the air chamber (3), and a flow controller (5) is arranged on the air blowing pipe (4); and the air chamber (3) is in communication with an air source by means of an air inlet pipe (1) having a pressure reducing valve (2). The method comprises: (1) heating an aluminum alloy in the reaction container (7) to form an aluminum alloy melt; and adding a tackifier; (2) performing heating, stirring and mixing; and (3) performing cooling to 680°C +/- 5°C; and introducing air into the air chamber (3) by means of the air source, wherein the air enters the mixed material by means of the air blowing pipe (4) to form tiny rising bubbles, and removing a foamed aluminum intermediate that has formed on a liquid level for air-cooling.

Description

Device and method for preparing foamed aluminum material by blowing method

Technical field

The invention belongs to the technical field of porous metal materials, and specifically relates to a device and a method for preparing foamed aluminum materials by an air blowing method.

Background technique

As a new type of material, foamed aluminum has excellent characteristics such as low density, sound insulation, heat insulation, shock absorption, electromagnetic shielding, etc. It has a wide range of applications in construction, transportation, aerospace and other industries. Its material types are divided into open-cell and closed-cell Two types, of which closed-cell materials are more widely used. The preparation methods of foamed aluminum materials mainly include blowing foaming method, powder metallurgy method and melt foaming method. The principle of the powder metallurgy method and the foaming agent foaming method is that the foaming agent is decomposed at high temperature and generates bubbles in the aluminum melt to obtain closed-cell foamed aluminum materials. These two methods have complicated processes and high costs.

The blowing and foaming method for preparing foamed aluminum has the advantages of low cost and continuous production. The principle is to melt aluminum or aluminum alloy, and then add silicon carbide, magnesium oxide and other high melting point material particles to the aluminum melt to increase the viscosity of the melt and increase the stability of the bubbles. The bottom blowing gas is introduced from the bottom of the container through the blowing pipe. In the melt, a large number of bubbles are continuously generated to rise to the top of the container, and after cooling, a foamed aluminum material with a certain air content is formed; the cell size of the material produced by the blowing and foaming method is generally 5-20mm, and the disadvantage is that the blowing It is difficult to control the dispersion of bubbles in the process, resulting in uneven density of the foamed aluminum material, which seriously affects the quality of the material.

On the other hand, foamed aluminum materials with a cell size of less than 5 mm have many advantages. When the cell size of the foamed aluminum is smaller, the cell shape is closer to a spherical shape, so that the cells are uniformly stressed, can withstand greater stress, and the mechanical properties of the material are improved. At the same time, the small-pore aluminum foam has less collapse during the cooling process, which is conducive to the large-scale production of the foam aluminum material, and is easier to flow and deform, which is beneficial to the secondary processing of the foam aluminum material.

The cell size of the foamed aluminum material is directly related to the size of the bubbles in the aluminum melt during the preparation process. Therefore, it is currently possible to reduce the size of the bubbles in the melt by reducing the diameter of the blowing pipe to control the cell size of the material; however, Reducing the diameter of the blowing pipe will limit the flow rate of the gas, thereby reducing the efficiency of bubble generation, making it difficult to achieve industrial production; in addition, after the bubbles reach the top, during the foam accumulation process, the bubbles will redistribute outwards along the center of the liquid surface. Increase the aggregation phenomenon of the bubbles and reduce the uniformity of the final cell.

Summary of the invention

technical problem

The solution to the problem

Technical solutions

The purpose of the present invention is to provide a device and method for preparing foamed aluminum material by blowing air method, which uses a plurality of small-sized blowing pipes to achieve precise control of bubble size. By setting the number and spacing of the blowing pipes, a large number of stable blowing pipes are controlled to form The tiny bubbles make the bubbles uniform and stable, which is conducive to the accumulation of the bubbles on the top of the container, and the aluminum foam material with small average cell size and good uniformity can be quickly prepared.

The device for preparing foamed aluminum material by the blowing method of the present invention includes a reaction vessel, a blowing tube and an air chamber; a stirring paddle is arranged in the reaction vessel; a number of blowing tubes pass through the bottom plate of the reaction vessel and are fixed on the bottom plate. The top of the air pipe is provided with an air blowing pipe head located in the reaction vessel, the bottom end of each air blowing pipe is connected to the air chamber, and the air blowing pipe is provided with a flow controller located between the air chamber and the bottom plate of the reaction vessel; The air inlet pipe of the pressure valve is connected with the air source; the inner diameter of the blowing pipe head is 0.05～0.15mm; the blowing pipes are arranged in several rows on the bottom plate; in each row of blowing pipes, the distance between two adjacent blowing pipes is 5～ 10mm; the distance between two adjacent rows of blowing pipes is 5-10mm.

In the above device, the air chamber is divided into a primary air chamber and a number of secondary air chambers; the air inlet of the primary air chamber is connected to the air source through a pipeline with a pressure reducing valve, and the primary air chamber is provided with several air chambers. Stage air outlet, each first stage air outlet is connected to the air inlet of a second air chamber through a pipe; each second air chamber is provided with several second air outlets, and each second air outlet is connected to the bottom of the blowing pipe End connected.

In the above device, the number of blowing pipes is at least 80.

In the above device, the material of the blowing tube and the blowing tube head is ceramic or stainless steel.

The volume ratio of the above-mentioned primary air chamber and secondary air chamber is 4-6.

The method for preparing foamed aluminum material by the blowing method of the present invention adopts the above-mentioned device and includes the following steps:

(1) Heat the aluminum alloy in the reaction vessel to exceed the melting temperature to form an aluminum alloy melt; add the tackifier silicon carbide powder or magnesium oxide powder to the aluminum alloy melt, and then keep it for at least 40 minutes to make the reaction vessel and The moisture in the tackifier evaporates;

(2) Raise the temperature of the materials in the reaction vessel to 700±10°C, turn on the stirring paddle to make the thickener evenly distributed in the aluminum alloy melt to form a mixture;

(3) Cool down the temperature of the mixture in the reaction vessel to 680±5℃; open the pressure reducing valve to inject air into the air chamber through the air source, and the air enters the mixture through the air blowing pipe, and adjust the flow controller to make each air blowing pipe The flow rate difference of ≤5%; the air entering the mixed material forms a large number of rising tiny bubbles, and the mixed material forms a foamed aluminum intermediate on the liquid surface; the foamed aluminum intermediate is taken out and air-cooled to room temperature to obtain the foamed aluminum material.

In the above method, the average flow rate of air in each blowing tube is 1 to 5 mL/min.

In the above method, the size of the micro bubbles is between 0.8 and 3.5 mm.

The particle size of the above-mentioned tackifier is ≤ 5 μm.

The pores in the above foamed aluminum material have a pore diameter of 3-10 mm and a porosity of 70-90%.

The above-mentioned pressure reducing valve is used to control the pressure in the blowing pipe to be stable, and to control the pressure in the blowing pipe to be 0.2±0.02MPa.

In the above method, the flow of the blowing pipe is controlled by a flow controller, and the number of working blowing pipes is adjusted by opening and closing the flow controller, which can be applied to the preparation of foamed aluminum materials with various pore sizes.

The beneficial effects of the invention

Beneficial effect

Compared with the prior art, the device and method for preparing foamed aluminum material by the blowing method provided by the present invention uses a plurality of small-sized blowing pipes to prepare the foamed aluminum material in a short time without destroying the continuity of the process; due to the blowing pipe A large number and reasonable distribution, can generate a large number of bubbles in a short time, reduce the probability of bubbles mixing with each other during the ascending process, effectively control the phenomenon of small bubbles merging into large bubbles, and solve the problem of preparing foam by blowing air in the past. The problem of uneven bubble size and large cavitation in the aluminum process that affects the material performance; it can effectively control the cell size, and at the same time realize the preparation of a foamed aluminum material with uniform cell distribution and good performance in a short time.

Brief description of the drawings

Description of the drawings

FIG. 1 is a schematic diagram of the structure of the device for preparing foamed aluminum material by the blowing method in an embodiment of the present invention;

FIG. 2 is a schematic view of the top structure of the bottom plate part in FIG. 1; FIG.

In the figure, 1. intake pipe, 2. pressure reducing valve, 3. air chamber (upper layer is secondary air chamber, lower layer is primary air chamber), 4. blowing pipe, 5. flow controller, 6, blowing pipe head , 7, reaction vessel, 8, bubbles, 9, mixture material, 10, stirring paddle.

Invention embodiment

Embodiments of the present invention

The aluminum alloy used in the embodiment of the present invention is A356 aluminum alloy.

The flow controller used in the embodiment of the present invention is a commercially available float flowmeter.

In the embodiment of the present invention, each secondary air chamber is connected with 3 to 4 blowing pipes.

The volume of the secondary air chamber in the embodiment of the present invention is 5 cm ² .

The silicon carbide powder or magnesium oxide powder in the embodiment of the present invention is a commercially available product.

The amount of the tackifier used in the embodiment of the present invention is tackifier: aluminum alloy melt=0.02-0.04 according to the mass ratio.

In the embodiment of the present invention, the volume ratio of the primary air chamber and the secondary air chamber is 4-6.

Example 1

The structure of the device for preparing foamed aluminum material by the blowing method is shown in Figure 1, and the top view structure is shown in Figure 2, including a reaction vessel 7, a blowing tube 4 and an air chamber 3; a stirring paddle 10 is provided in the reaction vessel 7; several blowing pipes 4 Pass through the bottom plate of the reaction vessel 7 and fix it on the bottom plate. The top end of each blowing pipe 4 is provided with a blowing pipe head 6 located in the reaction vessel 7, and the bottom end of each blowing pipe 4 is connected to the air chamber 3, and the blowing pipe 4 There is a flow controller 5 located between the gas chamber 3 and the bottom plate of the reaction vessel 7; the gas chamber 3 is in communication with a gas source through an air inlet pipe 1 with a pressure reducing valve 2;

The inner diameter of the blowing pipe head 6 is 0.1mm; each blowing pipe 4 is arranged in several rows on the bottom plate; in each row of blowing pipes 4, the distance between two adjacent blowing pipes 4 is 8mm; the distance between two adjacent rows of blowing pipes 4 is 8mm;

The air chamber 3 is divided into a primary air chamber and several secondary air chambers; the air inlet of the primary air chamber is connected to the air source through a pipe with a pressure reducing valve, and the primary air chamber is provided with several primary air outlets , Each primary air outlet is connected to the air inlet of a secondary air chamber through a pipe; each secondary air chamber is provided with several secondary air outlets, and each secondary air outlet is connected to the bottom end of the blowing pipe 4 ；

The number of blowing pipe 4 is 90;

The material of the blowing tube 4 and the blowing tube head 6 is ceramic;

The method for preparing foamed aluminum material by blowing method adopts the above-mentioned device and includes the following steps:

(1) Heat the aluminum alloy to 400°C in the reaction vessel to form an aluminum alloy melt; add silicon carbide powder with a particle size of ≤5μm as a thickening agent to the aluminum alloy melt, and then keep it for 40 minutes to increase the reaction vessel and The moisture in the adhesive volatilizes;

(2) Raise the temperature of the materials in the reaction vessel to 700±10°C, turn on the stirring paddle to make the tackifier evenly distributed in the aluminum alloy melt to form a mixture;

(3) Cool down the temperature of the mixture in the reaction vessel to 680±5℃; open the pressure reducing valve and pass air into the air chamber through the air source. The average flow rate of the air in each blowing tube is 3.7～4.3mL/min; the air is blown The air pipe enters the mixed material, and the flow rate difference in each blowing pipe is ≤5% by adjusting the flow controller; the air entering the mixed material forms a large number of rising tiny bubbles, the average size of the tiny bubbles is 0.8～3.5mm, and the mixed material A foamed aluminum intermediate is formed on the liquid surface; the foamed aluminum intermediate accumulated on the top of the liquid surface is taken out and air-cooled to room temperature to obtain a foamed aluminum material; the pores in the foamed aluminum material have a pore size of 3-10mm and a porosity of 80%;

The above-mentioned pressure reducing valve is used to control the pressure in the blowing pipe to be stable, and to control the pressure in the blowing pipe to be 0.2±0.02MPa;

The air pressure is controlled at 0.3MPa after passing through the pressure reducing valve;

The average size of the tiny bubbles generated by the blowing tube head is 1.7mm, and the average cell size of the foamed aluminum intermediate is 4.5mm.

Example 2

The structure of the device is the same as that of embodiment 1, the difference lies in:

(1) The inner diameter of the blowing pipe head is 0.15mm; the distance between two adjacent blowing pipes is 10mm; the distance between two adjacent rows of blowing pipes is 10mm;

(2) The number of blowing pipes is 62;

(3) The material of blowing pipe and blowing pipe head is stainless steel;

The method is the same as in Example 1, the difference is:

(1) Tackifier is magnesium oxide powder;

(2) The average flow rate of the air in each blowing tube is 5.7-6.3 mL/min; the average size of the tiny bubbles is 3.1 mm, and the porosity of the foamed aluminum material is 90%; the average cell size of the foamed aluminum intermediate is 7.5 mm.

Example 3

(1) The inner diameter of the blowing pipe head is 0.05mm; the distance between two adjacent blowing pipes is 5mm; the distance between two adjacent rows of blowing pipes is 5mm;

(2) The number of blowing pipes is 118;

(3) The material of blowing pipe and blowing pipe head is stainless steel;

The method is the same as in Example 1, the difference is:

(1) Tackifier is magnesium oxide powder;

(2) The average flow rate of the air in each blowing tube is 2.7-3.3mL/min; the average size of the tiny bubbles is 1.0mm, and the porosity of the foamed aluminum material is 70%; the average cell size of the foamed aluminum intermediate is 3.2mm.

Claims

A device for preparing foamed aluminum material by blowing method is characterized in that it comprises a reaction vessel, a blowing pipe and an air chamber; a stirring paddle is arranged in the reaction vessel; a plurality of blowing pipes pass through the bottom plate of the reaction vessel and are fixed on the bottom plate, each The top of the blowing pipe is provided with a blowing pipe head located in the reaction vessel, the bottom end of each blowing pipe is connected to the air chamber, and the blowing pipe is provided with a flow controller located between the air chamber and the bottom plate of the reaction vessel; The air inlet pipe of the pressure reducing valve is connected with the air source; the inner diameter of the blowing pipe head is 0.05～0.15mm; the blowing pipes are arranged in several rows on the bottom plate; in each row of blowing pipes, the distance between two adjacent blowing pipes is 5 ～10mm; the distance between two adjacent rows of blowing pipes is 5～10mm.
The device for preparing foamed aluminum material by blowing method according to claim 1, characterized in that the air chamber is divided into a primary air chamber and a plurality of secondary air chambers; the air inlet of the primary air chamber passes A pipeline with a pressure reducing valve is connected to the air source. The first-level air chamber is provided with a number of first-level air outlets, and each first-level air outlet is connected to the air inlet of a second-level air chamber through the pipeline; The chamber is provided with a plurality of secondary air outlets, and each secondary air outlet is connected with the bottom end of the blowing pipe.
The device for preparing foamed aluminum material by blowing method according to claim 1, characterized in that the number of blowing pipes is at least 80.
The device for preparing foamed aluminum material by blowing method according to claim 1, wherein the material of the blowing tube and the blowing tube head is ceramic or stainless steel.
The device for preparing foamed aluminum material by blowing method according to claim 1, characterized in that the volume ratio of the primary air chamber and the secondary air chamber is 4-6.
A method for preparing foamed aluminum material by an air blowing method, characterized in that the device according to claim 1 is adopted, and comprises the following steps:

(1) Heat the aluminum alloy in the reaction vessel to exceed the melting temperature to form an aluminum alloy melt; add the tackifier silicon carbide powder or magnesium oxide powder to the aluminum alloy melt, and then keep it for at least 40 minutes to make the reaction vessel and The moisture in the tackifier evaporates;

(2) Raise the temperature of the materials in the reaction vessel to 700±10°C, turn on the stirring paddle to make the tackifier evenly distributed in the aluminum alloy melt to form a mixture;

(3) Cool down the temperature of the mixture in the reaction vessel to 680±5℃; open the pressure reducing valve to inject air into the air chamber through the air source, and the air enters the mixture through the air blowing pipe, and adjust the flow controller to make each air blowing pipe The flow rate difference of ≤5%; the air entering the mixed material forms a large number of rising tiny bubbles, and the mixed material forms a foamed aluminum intermediate at the top of the liquid surface; the foamed aluminum intermediate is taken out and air-cooled to room temperature to obtain a foamed aluminum material.
The method for preparing foamed aluminum material by an air blowing method according to claim 6, wherein the average flow rate of the air in each air blowing tube is 1 to 5 mL/min.
The method for preparing foamed aluminum material by the blowing method according to claim 6, wherein the size of the tiny bubbles is between 0.8 mm and 3.5 mm.
The method for preparing foamed aluminum material by the blowing method according to claim 6, characterized in that the particle size of the tackifier is less than or equal to 5 μm.
The method for preparing foamed aluminum material by blowing air according to claim 6, characterized in that the pores inside the foamed aluminum material have a pore size of 3-10 mm and a porosity of 70-90%.