阅读说明：本技术 一种开闭孔共存结构的泡沫铝及其制备方法 (Foamed aluminum with open-close hole coexisting structure and preparation method thereof ) 是由 左大中 张晓玲 于 2020-07-12 设计创作，主要内容包括：本发明公开一种开闭孔共存结构的泡沫铝及其制备方法,将开孔泡沫铝制备技术与闭孔泡沫铝制备技术相融合,相关制备方法包括如下步骤：首先选择适当的开孔泡沫铝造孔剂放入模具中预热,接近待渗入含有发泡剂的铝液温度；同时,将纯铝或铝合金加热至熔化,再加入发泡剂搅拌均匀；然后在压力下,迅速将含有发泡剂的铝液渗入到造孔剂的缝隙中；待渗入完成后,将压力迅速调整为常压,使发泡剂工作产生闭孔气泡,冷却后从模具中取出成型后的泡沫铝材料并利用水或其它水溶液将造孔剂去除,得到开闭孔共存结构的泡沫铝材料。(The invention discloses foamed aluminum with an open-close pore coexisting structure and a preparation method thereof, wherein the preparation technology of open-pore foamed aluminum is fused with the preparation technology of closed-pore foamed aluminum, and the related preparation method comprises the following steps: firstly, selecting a proper amount of open-cell foamed aluminum pore-forming agent, placing the open-cell foamed aluminum pore-forming agent into a mold, and preheating the open-cell foamed aluminum pore-forming agent to be close to the temperature of aluminum liquid containing a foaming agent to be permeated; meanwhile, heating pure aluminum or aluminum alloy to be molten, adding a foaming agent and uniformly stirring; then, under pressure, rapidly infiltrating aluminum liquid containing a foaming agent into gaps of the pore-forming agent; and after the permeation is finished, rapidly adjusting the pressure to normal pressure to enable the foaming agent to work to generate closed-cell bubbles, cooling, taking out the molded foamed aluminum material from the mold, and removing the pore-forming agent by using water or other aqueous solutions to obtain the foamed aluminum material with the open-close pore coexisting structure.)

1. An open-and-close pore coexisting structure aluminum foam, characterized in that: the structure of the foamed aluminum comprises open pores and closed pores.

2. A preparation method of foamed aluminum with an open-close pore coexisting structure comprises the following steps:

(1) selecting a pore-forming agent for preparing open pores, putting the pore-forming agent into a mold, compacting the pore-forming agent through extrusion and oscillation treatment, and then preheating the pore-forming agent;

(2) melting pure aluminum or aluminum alloy in a smelting furnace to obtain pure aluminum or aluminum alloy melt, adding a tackifier and uniformly stirring to enable bubbles to remain in the pure aluminum or aluminum alloy melt;

(3) adding a foaming agent subjected to preheating treatment into the tackified pure aluminum or aluminum alloy melt, and continuously stirring to ensure that the foaming agent is uniformly distributed;

(4) under pressure, infiltrating pure aluminum or aluminum alloy melt mixed with foaming agent into the preheated pore-forming agent gaps;

(5) after the pure aluminum or aluminum alloy melt mixed with the foaming agent is infiltrated, adjusting the pressure to be normal pressure, and continuously preserving the heat to ensure that the foaming agent works to generate closed-cell bubbles;

(6) after cooling, the foamed aluminum material containing the pore-forming agent and closed pores is taken out of the mold, and the pore-forming agent is removed with warm water or other aqueous solution to obtain foamed aluminum having an open-closed pore coexisting structure.

3. The production method according to claim 2, wherein the mold base for producing the open-and closed-cell coexistent structure aluminum foam is provided with air holes for exhausting gas in gaps between the particles.

4. The preparation method according to claim 2, wherein the pore-forming agent for preparing the open pores is sodium chloride particles, calcium carbonate particles, kaolin and bentonite mixed particles, urea particles, vermiculite, or the like.

5. The preparation method according to claim 2, wherein the preheating temperature in step (1) is 550-950 ℃; the pressure in the step (4) is 5-80 MPa; the temperature of the warm water or other aqueous solution in the step (6) is 40-85 ℃.

6. The method according to claim 2, wherein the aluminum alloy is cast aluminum alloy A359, wrought alloy 1061, 3003, 6061, or the like, or an alloy of aluminum and other metals in different proportions.

7. The production method according to claim 2, wherein the tackifier is silicon carbide, aluminum oxide, metallic calcium; the foaming agent is titanium hydride (TiH)₂) Or zirconium hydride (ZrH)₂）。

8. The preparation method according to claim 2, wherein the other aqueous solution for removing the pore-forming agent is an aqueous solution to which a dispersant is added, the dispersant being an inorganic dispersant including silicates (such as water glass) and alkali metal phosphates (such as sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate) or an organic dispersant including triethylhexylphosphoric acid, sodium dodecylsulfate, methylpentanol, cellulose derivatives, polyacrylamide, guar gum, and fatty acid polyglycol ester.

9. The method according to claim 2, wherein the pure aluminum or aluminum alloy is melted in a melting furnace by deslagging and refining.

10. An open-and-close pore coexisting structure aluminum foam, characterized in that: the method according to any one of claims 2 to 9.

Technical Field

The invention relates to foamed aluminum and a preparation method thereof, in particular to a preparation method of foamed aluminum with both an open-cell structure and a closed-cell structure, belonging to the technical field of foamed metal design and preparation.

Background

Foamed aluminum is a novel functional material, which is a light metal material with innumerable bubbles or holes dispersed in an aluminum or aluminum alloy matrix, the general porosity is between 40 and 98 percent, and the foamed aluminum not only has the general characteristics of a porous foamed material, but also retains the characteristics (such as conductivity, plasticity, toughness, flame retardance and the like) of the metal material. Due to the unique structure of the foamed aluminum, the foamed aluminum has the characteristics of structural materials and functional materials. As a structural material, it has the characteristics of light weight and high specific strength; as a functional material, the material has various physical properties of sound absorption, heat insulation, heat dissipation, flame retardance, shock absorption, damping, impact energy absorption, electromagnetic shielding and the like, so that the material can be used as a light structure and a shock absorption medium in the fields of aerospace, weaponry, automobiles and the like, and can also be used as a functional material in the aspects of sound insulation of highways, noise reduction of buildings, electromagnetic wave protection of electronic instruments and the like.

The foamed aluminum is successfully manufactured in the twenty-century forty years till now, the development process is carried out for nearly seventy years, and at present, a plurality of methods for producing the foamed aluminum are successively developed in the countries such as the United states, Japan, Britain, Germany, Canada and the like, a plurality of technical patents are obtained, and the foamed aluminum is made into materials such as pipes, strips and the like and is applied to a plurality of fields. The research on the foamed aluminum in China is started from the late stage of the eighties of the twentieth century, and currently, research institutions in Beijing, Shenyang, Chengdu, Guizhou, Dalian and the like do some research works and obtain a series of research results. The cell morphology of the existing foamed aluminum is generally classified into open-cell foamed aluminum and closed-cell foamed aluminum, the open-cell foamed aluminum is also called open-cell foamed aluminum, the internal pores of the open-cell foamed aluminum are connected, the internal pores of the closed-cell foamed aluminum are not connected, and the pores are independent. At present, no report on the production and preparation of foamed aluminum with open-closed cell coexisting structure exists at home and abroad.

The existing preparation methods of closed-cell foamed aluminum include a solid-gas eutectic solidification method, a powder metallurgy method, a melt foaming method and the like. The melt foaming method is the most mature preparation method of closed-cell foamed aluminum at present, is widely applied to actual production, and can be divided into two types according to specific processes: one is foaming agent foaming method, and the other is blowing foaming method, and the method can be used for producing foamed metal with large size. The solid-gas eutectic solidification method has more variable factors in the preparation process, and the development of the method is restricted by the safety problem and the complex process control. The foamed aluminum prepared by the powder metallurgy method has good quality, relatively stable performance and higher reproducibility, and can be used for preparing parts with complex shapes and near finished sizes.

The existing preparation methods of open-cell foamed aluminum comprise a seepage casting method, an investment casting method, an electrolytic deposition method and the like. The infiltration casting method is also called a grain-around casting method, and is specifically characterized in that removable grains are placed in a mold, and the grains are subjected to extrusion and vibration treatment to densify the grains, and are subjected to preheating treatment. Pouring the molten pure aluminum or aluminum alloy which is smelted in advance into a mold with removable particles, applying certain pressure to enable the pure aluminum or aluminum alloy to seep into gaps of the removable particles, cooling and removing the removable particles to obtain the open-cell foamed aluminum, wherein the open-cell foamed aluminum with good aperture uniformity can be obtained by the method, but the porosity is relatively low; the difficulty of how to remove the heat-resistant model without damaging the foam phase structure is similar to the investment casting method and the seepage casting method, which increases the process difficulty and the cost; the electrolytic deposition method can prepare the foamed aluminum with high porosity, and the foamed aluminum has good pore connectivity, uniform distribution and large porosity, but has long working procedure, complex operation and limited application prospect.

Disclosure of Invention

The invention provides a foamed aluminum product with coexisting open cells and closed cells, which can improve the porosity of foamed aluminum prepared by a seepage casting method, and can widen the application of the closed cell foamed aluminum in the fields of seepage, gas permeation and the like as the pore diameter of the open cells can be adjusted by the size of a pore-forming agent.

The technical scheme of the invention comprises the following aspects:

an open-and-closed pore coexisting structure of aluminum foam, which comprises both open pores and closed pores in the structure.

A preparation method of foamed aluminum with an open-close pore coexisting structure comprises the following steps:

(1) selecting a pore-forming agent for preparing open pores, putting the pore-forming agent into a mold, compacting the pore-forming agent through extrusion and oscillation treatment, and then preheating the pore-forming agent;

(2) melting pure aluminum or aluminum alloy in a smelting furnace to obtain pure aluminum or aluminum alloy melt, adding a tackifier and uniformly stirring to enable bubbles to remain in the pure aluminum or aluminum alloy melt;

(3) adding a foaming agent subjected to preheating treatment into the tackified pure aluminum or aluminum alloy melt, and continuously stirring to ensure that the foaming agent is uniformly distributed;

(4) under pressure, infiltrating pure aluminum or aluminum alloy melt mixed with foaming agent into the preheated pore-forming agent gaps;

(5) after the pure aluminum or aluminum alloy melt mixed with the foaming agent is infiltrated, adjusting the pressure to be normal pressure, and continuously preserving the heat to ensure that the foaming agent works to generate closed-cell bubbles;

(6) after cooling, the foamed aluminum material containing the pore-forming agent and closed pores is taken out of the mold, and the pore-forming agent is removed with warm water or other aqueous solution to obtain foamed aluminum having an open-closed pore coexisting structure.

Preferably, in the above production method, the mold base for producing the open-closed pore coexisting structure foamed aluminum is provided with air holes for exhausting air in gaps between the particles.

Preferably, in the above preparation method, the pore-forming agent for preparing the open pores is sodium chloride particles, calcium carbonate particles, kaolin and bentonite mixed particles, urea particles, vermiculite, or the like.

Preferably, in the above preparation method, the preheating temperature in step (1) is 550-; the pressure in the step (4) is 5-80 MPa; the temperature of the warm water or other aqueous solution in the step (6) is 40-85 ℃.

Preferably, in the above preparation method, the aluminum alloy is cast aluminum alloy a359, forged alloys 1061, 3003, 6061, etc., or alloys of aluminum and other metals in different proportions.

Preferably, in the above preparation method, the tackifier is silicon carbide, aluminum oxide, calcium metal; the foaming agent is titanium hydride (TiH)₂) Or zirconium hydride (ZrH)₂）。

Preferably, in the above preparation method, the other aqueous solution for removing the pore-forming agent is an aqueous solution to which a dispersant is added, the dispersant is an inorganic dispersant or an organic dispersant, the inorganic dispersant includes silicates (e.g., water glass) and alkali metal phosphates (e.g., sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate), and the organic dispersant includes triethylhexylphosphoric acid, sodium dodecylsulfate, methylpentanol, cellulose derivatives, polyacrylamide, guar gum, and fatty acid polyglycol ester.

Preferably, in the above preparation method, the pure aluminum or aluminum alloy is melted in a melting furnace and is subjected to deslagging and refining.

The invention also relates to the foamed aluminum prepared by the preparation method.

The technical scheme of the invention has the beneficial effects that:

the method breaks through the limitation that the existing foamed aluminum only has two cell forms of open cell and closed cell, obtains the third cell form of the foamed aluminum, namely the open-closed cell coexisting structure cell, and can improve the porosity of the open-cell foamed aluminum compared with the open-cell foamed aluminum prepared by a seepage casting method. The pore size of the open pore can be adjusted by the size of the pore-forming agent, so that the application of the porous material in the fields of seepage, gas permeation and the like can be effectively widened compared with closed-pore foamed aluminum. The scheme is also original invention on the key process, reduces the process complexity, and can realize the continuous production of the foamed aluminum with the open-close hole coexisting structure by controlling the viscosity, the seepage temperature, the seepage pressure and the like of the aluminum liquid in the preparation process. The method can realize the foam hole control of the open-close hole coexisting structure foam aluminum by changing the size and the shape of the pore-forming agent and adding different types, different adding amounts, different particle sizes and different pretreated foaming agents, and the control method of the hole-shaped structure has realizability and better meets the requirement of practical application on product diversity.

Compared with the existing open-cell foamed aluminum and closed-cell foamed aluminum, the invention has the following specific characteristics:

(1) by selecting the type, size and shape of the pore-forming agent, the pore structure parameter characteristics of the open-closed cell coexisting structure foamed aluminum through hole part can be controlled, so that the foamed aluminum has a permeation function while lighter weight is obtained;

(2) by selecting the type, granularity, addition amount and pretreatment mode of the foaming agent, the control of parameters such as gas amount and decomposition rate in the melt is realized, and the characteristics such as closed-cell structure parameters in the open-closed coexisting structure foamed aluminum are further controlled;

(3) the preparation process of the foamed aluminum with the open-close hole coexisting structure is effectively realized by controlling pressure conversion. Under the common condition, open-cell foamed aluminum needs to realize the seepage of aluminum liquid in a pore-forming agent under a pressurization condition, while closed-cell foamed aluminum needs to realize the formation, growth and shaping of cells under a normal pressure condition, which is contradictory in the realization of the process of open-cell and closed-cell coexisting structure foamed aluminum, but the problem is solved by controlling pressure conversion.

(4) The invention effectively solves the contradiction by controlling the pressure level and the pressure maintaining time, so that the aluminum liquid mixed with the foaming agent can continue to foam after permeating the pore-forming agent, and the invention is an important link for realizing the process of the invention.