Small-aperture foamed aluminum composite material, powder aluminum alloy for foaming of small-aperture foamed aluminum composite material and preparation method

Abstract

The invention belongs to the technical field of foamed aluminum materials, and relates to a small-aperture foamed aluminum composite material, a powder aluminum alloy for foaming of the small-aperture foamed aluminum composite material and a preparation method of the small-aperture foamed aluminum composite material, the powder aluminum alloy for foaming is Al-Si-Cu alloy or Al-Si-Cu-Zn alloy, the volume fraction of Al2Cu is 12-25%, and the particle size of the Al2Cu is smaller than or equal to 1 [mu] m; preparing powder aluminum alloy for foaming by adopting gas atomization powder preparation equipment; when the foamed aluminum composite material is prepared, firstly, foaming powder is prepared, then powder briquettes are obtained through briquetting forming, then a foaming prefabricated body is prepared through hot rolling, and finally the foamed aluminum composite material is prepared through foaming. The small-aperture foamed aluminum composite material comprises a foam layer, and an upper substrate layer and a lower substrate layer which are positioned on two sides of the foam layer. The Al2Cu phase in the powder aluminum alloy for foaming is uniformly dispersed and distributed; the preparation method of the powder aluminum alloy for foaming is simple and feasible; the foamed aluminum composite material is integrally formed. And the pore size distribution of the small-pore-diameter foamed aluminum composite material is uniform.

Description

Technical Field

[0001] This invention belongs to the field of aluminum foam material technology, and relates to a small-pore aluminum foam composite material, its foaming powder aluminum alloy, and its preparation method. Background Technology

[0002] The advantages of aluminum foam stem from the inherent strengths of aluminum metal—lightweight and high specific strength—while its porous structure endows the material with extraordinary properties surpassing those of traditional metals. Due to its highly efficient energy absorption, closed-cell aluminum foam is beginning to be used in automotive collision avoidance systems; open-cell aluminum foam possesses excellent sound absorption properties, making it a primary material for noise reduction projects in high-speed rail and subways; and the adjustable mechanical properties of gradient aluminum foam meet the dual requirements of "lightweight + high stiffness" for aerospace components. This multi-functional characteristic makes it an ideal alternative to both traditional and functional materials.

[0003] To meet the requirements for energy absorption, sound insulation, and strength in the aforementioned applications, aluminum foam is typically designed as a three-layer structure similar to a sandwich. When using the traditional melt foaming method to prepare a sandwich structure, the aluminum foam bread is first foamed at high temperature, then cut into the required shape, and finally welded or glued to form a three-layer composite structure. In contrast, the powder metallurgy method prepares the sandwich structure as a single piece. Specifically, metal powder and a foaming agent are used as the core layer materials, with aluminum panels on both sides. After pressing into a composite blank (i.e., a foamed preform), the core layer is then heated to foam, resulting in a single piece of aluminum foam. Compared to the traditional melt foaming method, powder metallurgy foaming does not require high-temperature melting, making this method more environmentally friendly and energy-efficient.

[0004] For example, CN103589892A relates to a method for preparing low-density, small-pore-size powder metallurgy foamed aluminum composite structures. This method first uses a vibrating screen to select TiH2 powder with uniform particle size as a foaming agent; then, aluminum powder, magnesium powder, silicon powder, and foaming agent powder are mixed evenly in a certain proportion and extruded to prepare a foamable preform; finally, the foamable preform is placed into a composite mold, preheated for a period of time, and then quickly transferred to a heat-insulating furnace for foaming. After cooling, the foamed aluminum composite structure is obtained. However, the foamed aluminum prepared by this method has a relatively large and uneven pore size.

[0005] Therefore, it is of great significance to study a small-pore aluminum foam composite material and its foaming powder aluminum alloy and preparation method to solve the problems existing in the prior art. Summary of the Invention

[0006] The purpose of this invention is to solve the problem of large and uneven pore size in the existing aluminum foam technology, and to provide a small-pore aluminum foam composite material, a powdered aluminum alloy for foaming, and a preparation method thereof.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A powdered aluminum alloy for foaming, comprising an Al-Si-Cu alloy or an Al-Si-Cu-Zn alloy, wherein the Si content is 5~9 wt.% and the Cu content is 5~25 wt.%.

[0009] The volume fraction of Al2Cu is 12-25%, and the particle size of Al2Cu is less than or equal to 1 μm.

[0010] One of the objectives of this invention is to provide a powdered aluminum alloy that can be used for foaming to prepare aluminum foam composite materials with small and uniform pore sizes.

[0011] In Al-Si-Cu or Al-Si-Cu-Zn alloy systems, it has been found that because the melting point of the Al2Cu phase is lower than that of the matrix, during foaming, when Al2Cu melts, the gas produced by the decomposition of the foaming agent tends to flow into the liquid Al2Cu, where the bubbles nucleate and grow. Furthermore, the pore size can be controlled by adjusting the size of Al2Cu.

[0012] When the volume fraction is low (below 12%), the Al2Cu phase is sparsely distributed with few nucleation sites, and bubble nucleation mainly relies on spontaneous nucleation of the melt, resulting in uneven pore size distribution and a larger average pore size. When the volume fraction is high (above 25%), the Al2Cu phase coarsens and aggregates, forming a continuous network structure, which inhibits bubble nucleation, leading to increased pore size and the appearance of large pore defects. When the volume fraction is moderate, the Al2Cu phase is uniformly dispersed, providing a large number of bubble nucleation sites, increasing the bubble nucleation density, significantly reducing the pore size, and making the pore size distribution more concentrated.

[0013] like Figure 2 As shown, the fine and dispersed Al2Cu phase can provide a large number of bubble nucleation sites, promoting uniform bubble nucleation and forming a closed-pore structure with small pore size and uniform distribution. Simultaneously, it pins dislocations on the pore walls, inhibits collapse, and improves pore wall density and gas utilization. Figure 1 As shown, the large, continuous network structure of the Al2Cu phase has insufficient nucleation sites, resulting in a reduced bubble nucleation density, coarsened pore size, and uneven distribution.

[0014] As a preferred technical solution:

[0015] The above-mentioned powdered aluminum alloy for foaming has a Zn content ≥ 5wt.% and a melting temperature (i.e. melting point) of 530~564℃.

[0016] To ensure that the gas generated by the decomposition of the foaming agent is fully utilized for foaming, the melting point of the aluminum powder alloy used for foaming needs to be lower than the decomposition temperature of the foaming agent. Typically, to control the volume fraction of the Al₂Cu phase, the amount of Cu added needs to be controlled. However, this results in a relatively high melting point for the foaming powder, potentially even exceeding the temperature at which the foaming agent reaches its maximum decomposition rate. The addition of Zn alloying elements to Si and Cu lowers the melting temperature of the aluminum powder alloy used for foaming. When the Zn content is ≥5 wt.%, the melting temperature is 530–564 °C. The temperature at which the foaming agent TiH₂ decomposes at its maximum rate is 568 °C. When the melting point of the aluminum powder alloy is lower than the temperature at which TiH₂ decomposes at its maximum rate, it ensures that a large amount of gas will not decompose and escape prematurely before the matrix is ​​completely melted during the foaming process, which is beneficial for forming small and uniform pores.

[0017] The present invention also provides a method for preparing a foaming powdered aluminum alloy as described above, wherein the foaming powdered aluminum alloy is prepared using a gas atomization powder preparation device;

[0018] The gas atomization powder production equipment is an existing technology, comprising a melting system, an atomization system, and a collection system. The main component of the melting system is the melting furnace. The prepared alloy raw materials are added to the melting furnace and heated to the target melting temperature until completely melted and stirred, forming a homogeneous melt. The molten liquid flows through the outlet at the bottom of the melting furnace, through a guide pipe, and enters the atomization system. Simultaneously, high-pressure gas (such as nitrogen, argon, or other inert gases suitable for aluminum alloys) in the atomization system is accelerated to supersonic speed through nozzles, forming a high-speed air jet. This jet collides with the molten liquid, breaking it into droplets that fall freely within the atomization system's container and rapidly solidify into metal powder. The powder then enters the collection system with the airflow, and after sieving, the desired particle size of the finished powder is obtained.

[0019] A second objective of this invention is to provide a method for preparing the aforementioned powdered aluminum alloy for foaming, using a gas atomization powder preparation device. The inventors discovered that appropriate nitrogen pressure and nozzle orifice diameter are needed to control the size and volume fraction of the target Al₂Cu phase.

[0020] The nitrogen pressure in the gas atomization powder making equipment is 3~6MPa;

[0021] High-pressure gas pressure: The pressure of high-pressure gas affects the gas flow velocity and momentum, thus influencing the degree of melt fragmentation and the cooling rate. When the high-pressure gas pressure is low (below 3 MPa), the gas flow velocity is low, the melt fragmentation is insufficient, the cooling rate is slow, and the growth time of the Al2Cu phase is prolonged, leading to coarsening of the Al2Cu phase and the formation of a continuous network structure. During foaming, the bubble nucleation density decreases, and the pore size becomes coarser and unevenly distributed. When the high-pressure gas pressure is high (above 6 MPa), the gas flow velocity is too high, the melt is excessively fragmented, the cooling rate is extremely fast, atomic diffusion is significantly suppressed, Al2Cu phase is difficult to nucleate, too few Al2Cu phases are formed, the Al2Cu phase distribution is sparse, the heterogeneous nucleation ability is weak, and bubble nucleation mainly depends on spontaneous nucleation of the melt, resulting in uneven pore size distribution and a larger average pore size.

[0022] The nozzle orifice diameter is 0.8~1.2mm;

[0023] Nozzle orifice diameter: The nozzle orifice diameter indirectly controls the volume fraction and size of the Al2Cu phase by affecting the droplet size. A larger orifice diameter produces larger droplets, prolongs the cooling time, promotes the coarsening of the Al2Cu phase, and forms a continuous network structure. During foaming, the bubble nucleation density decreases, and the pore size becomes coarser and unevenly distributed. Conversely, a smaller orifice diameter produces smaller droplets, accelerates the cooling rate, inhibits the growth of the Al2Cu phase and reduces its volume fraction. The Al2Cu phase is sparsely distributed, has weak heterogeneous nucleation ability, and bubble nucleation mainly relies on spontaneous nucleation of the melt, resulting in uneven pore size distribution and a larger average pore size.

[0024] In the above-described method for preparing foamed aluminum alloy powder, the melting temperature of the gas atomization powder preparation equipment is 100~200K, and the gas-liquid mass flow rate ratio is 1~3%.

[0025] Melting temperature: The selection of melting temperature should take into account that the melt superheat is within a suitable range. Melt superheat refers to the part of the melt temperature that is higher than the liquidus temperature. It is a key process parameter for gas atomization powder production and needs to be controlled within 100~200K.

[0026] Gas-liquid mass flow rate ratio: The gas-liquid mass flow rate ratio refers to the ratio of the mass flow rate of the high-pressure atomizing gas (gas phase) to the mass flow rate of the molten metal (liquid phase) in the nozzle of the atomization system. It reflects the gas's ability to break up the melt and directly affects the residence time and cooling uniformity of the melt. It usually needs to be controlled within 1 to 3%.

[0027] This invention provides a method for preparing aluminum foam composite material, using a foaming powdered aluminum alloy as described above, comprising the following steps:

[0028] (1) Preparation of foaming powder;

[0029] The foaming powder aluminum alloy is mixed evenly with the foaming agent to obtain foaming powder;

[0030] (2) Powder briquettes;

[0031] The foamed powder obtained in step (1) is pressed into a block to obtain a powder block;

[0032] (3) Hot rolling to prepare foamed preforms;

[0033] The powder block obtained in step (2) is assembled into an aluminum lower substrate with a square groove, so that the powder block just fills the square groove. Then, an aluminum upper substrate is placed on the aluminum lower substrate filled with powder block, so that the square groove is completely covered by the upper substrate. The foamed preform is obtained by hot rolling. The deformation of hot rolling is ≥70%. There are still many pores in the powder block. If foaming is done directly, these pores will provide escape channels for gas, which will prevent the formation of bubbles. Hot rolling is needed to reduce the porosity. When the deformation of hot rolling is less than 70%, the pores cannot be completely healed, which can easily lead to problems such as uneven bubble formation during foaming.

[0034] (4) The foamed preform obtained in step (3) is foamed to obtain a foamed aluminum composite material with a sandwich structure.

[0035] The third objective of this invention is to provide a method for preparing foamed aluminum composite materials using the above-mentioned foaming powdered aluminum alloy. The method of this invention can integrally mold sandwich-structured foamed aluminum composite materials, eliminating the steps of bonding and welding the foamed aluminum to the upper and lower substrates after foaming compared to traditional methods.

[0036] As a preferred technical solution:

[0037] In the preparation method of the above-mentioned aluminum foam composite material, the content of foaming agent in the foaming powder in step (1) is 0.3~1.2 wt.%.

[0038] A suitable foaming agent is TiH2, a common foaming agent with good wettability with the aluminum matrix, high gas production per unit mass, rapid diffusion, and small molecular weight of H2 produced during decomposition. The amount of foaming agent added should be appropriate. If the amount added is too small, the amount of hydrogen produced during foaming is too low, resulting in fewer bubbles and lower porosity of the foamed aluminum. If the amount added is too large, the amount of hydrogen produced during foaming is excessive, increasing the number of bubbles, leading to severe bubble coalescence or bubble rupture, ultimately resulting in uneven bubble distribution. Those skilled in the art can adjust the amount according to specific bubble size requirements. The content of the foaming agent in this invention can, for example, be 0.3~1.2 wt.%.

[0039] In the above-described method for preparing aluminum foam composite material, the pressure of the compression molding in step (2) is 200~400MPa.

[0040] Powder briquettes are typically produced using a tablet press (i.e., room temperature pressing, a concept relative to high-temperature pressing, commonly referred to as cold pressing by those skilled in the art). The briquetting process is designed to ensure successful briquetting. For example, insufficient cold pressing pressure will result in insufficient interlocking force between the powder particles, preventing briquette formation. Generally, the cold pressing pressure can be set to no less than 200 MPa. For example, the powder can be loaded into a mold, and pressure can be applied to and maintained using a tablet press. After pressure maintenance, demolding is performed to obtain the powder briquettes. The mold is a rectangular lobed mold, capable of producing powder briquettes with a base area of ​​20mm × 25mm and varying thicknesses. The lobed design facilitates demolding. Multiple powder briquettes can be produced as needed. The use of a tablet press to produce powder briquettes is a conventional technique and will not be described in detail here.

[0041] In the preparation method of the foamed aluminum composite material described above, the solidus temperature of the lower aluminum substrate and the upper aluminum substrate in step (3) is higher than the liquidus temperature of the foaming powder. As is known, the solidus temperature of the aluminum substrate needs to be higher than the liquidus temperature of the foaming powder. When the solidus temperature of the substrate is less than or equal to the liquidus temperature of the foaming powder, the substrate will undergo severe melting during the foaming process, resulting in an overall decrease in the performance of the composite foam board. Generally, the solidus temperature of the substrate should be 30°C higher than the liquidus temperature of the foaming powder. In this invention, the upper and lower substrates are preferably made of ternary aluminum alloy. Compared with pure aluminum substrate, ternary aluminum alloy has higher strength, and the thermal deformation of the substrate and the sandwich powder briquettes is better matched during hot rolling.

[0042] In the above-mentioned method for preparing a foamed aluminum composite material, the foaming temperature in step (4) is 100~200℃ higher than the melting temperature of the aluminum powder alloy used for foaming, the foaming time is 3~10min, and the cooling rate after foaming is 60~100℃ / min.

[0043] Foaming is a known technology, and it requires the matrix to be in a liquid state to allow space for cell growth. For example, the foaming temperature needs to be 100-200°C higher than the melting temperature of the aluminum alloy powder used for foaming. When the difference between the foaming temperature and the melting temperature of the foaming powder is too small, the melt viscosity is too high, the gas channels are relatively simple, and large through-holes are easily formed. When the difference is too large, the melt viscosity is low, the resulting cells have poor roundness and are prone to merging, leading to uneven cell structure.

[0044] If the foaming time is too short, the foaming agent may not decompose sufficiently, resulting in insufficient gas release, low porosity, and a small number of bubbles with uneven distribution. If the foaming time is too long, the gas may diffuse or escape excessively, and the melt may become less viscous due to overheating, leading to bubble merging, pore wall collapse, the formation of large or interconnected pores, or even structural collapse.

[0045] Because the sample needs to be rapidly heated to the foaming temperature in a short time during foaming, it is usually necessary to preheat the sample before foaming to ensure that the sample can be heated uniformly and rapidly to the required foaming temperature. The preheating temperature is 450~500℃, and the holding time is 10~30 minutes. If the holding time is too short, the sample will be preheated unevenly, resulting in uneven decomposition rate of the foaming agent, uneven cell distribution, and inconsistent pore size during foaming. If the holding time is too long, too much foaming agent will be oxidized, resulting in a decrease in the total amount of decomposed gas and a decrease in porosity. If the preheating temperature is too low, the difference between the preheating temperature and the foaming temperature will be too large, failing to achieve the preheating effect. The sample cannot be heated uniformly and rapidly from the preheating temperature to the foaming temperature, resulting in uneven decomposition rate of the foaming agent, uneven cell distribution, and inconsistent pore size during foaming. If the preheating temperature is too high, the foaming agent will decompose prematurely upon heating, resulting in segmented foaming of the matrix, uneven cell distribution, and inconsistent pore size.

[0046] The cooling rate should generally be controlled between 60 and 100 °C / min. At a suitable cooling rate, the melt solidifies slowly and uniformly, and the atoms in the pore walls are fully densified through diffusion. Bubble growth is effectively constrained, ultimately forming a high-quality closed-cell structure with uniform pore size, regular shape, and dense pore walls. If the cooling rate is too fast, the pore walls cannot be densified in time due to the rapid drop in viscosity when the high-temperature melt solidifies quickly. Insufficient atomic diffusion leads to loose and porous pore walls, or even local collapse. Bubble cells merge to form large pores or interconnected pores, reducing the density of the bubble cells. If the cooling rate is too slow, the melt remains in the high-temperature zone for a long time. The decomposition residue of the foaming agent or alloying elements are prone to precipitate and form second-phase particles, interfering with bubble growth and resulting in uneven bubble size distribution or the appearance of irregular polyhedral pores.

[0047] The present invention also provides a small-pore aluminum foam composite material, prepared by the method described in any of the preceding claims. The small-pore aluminum foam composite material includes a foam layer and an upper substrate layer and a lower substrate layer located on both sides thereon; the foam diameter of the foam layer is 0.54~1.24 mm, the porosity is greater than 50%, and the number of foam cells per unit area is 0.9~2.3 cells / mm. 2 .

[0048] Beneficial effects:

[0049] (1) A powdered aluminum alloy for foaming according to the present invention has a uniformly dispersed Al2Cu phase, a significantly reduced pore size, and a more concentrated pore size distribution;

[0050] (2) The method for preparing foamed aluminum alloy of the present invention is simple and easy to operate;

[0051] (3) The method for preparing a foamed aluminum composite material of the present invention can integrally mold a sandwich structured foamed aluminum composite material, and the bond between the substrate and the foamed aluminum is stronger;

[0052] (4) A small-pore aluminum foam composite material of the present invention has a uniform distribution of pore size and uniform pore size. Attached Figure Description

[0053] Figure 1 SEM image of Al2Cu powder with a continuous network structure;

[0054] Figure 2 This is a SEM image of Al2Cu powder with a diffuse distribution. Detailed Implementation

[0055] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0056] The test methods involved in the performance indicators in the embodiments and comparative examples of this invention are as follows:

[0057] Melting temperature and solid-liquid phase difference of aluminum alloy: The melting temperature of the sample was characterized using a NETZSCH STA 449C model synchronous thermal analyzer. An inert atmosphere (such as Ar) was used, and the heating rate was 10 K / min. The melting temperature and solid-liquid phase difference of the aluminum alloy were marked using the NETZSCH Proteus Themal Analysis 8.0.3 software provided with the instrument. The melting temperature is the liquidus temperature, which is the peak point of the maximum endothermic peak. The solid-liquid phase difference is the temperature difference between the melting peak initiation temperature (i.e., solidus temperature) and the melting temperature (liquidus temperature).

[0058] Al2Cu volume fraction and particle size: The alloy powder prepared by gas atomization at a weight ratio of 1:10 was mixed with cold-mounting resin Mounte Epox9 (composed of epoxy resin and epoxy curing agent at a weight ratio of 100:46, epoxy resin product number: 21-3100-040, epoxy curing agent product number: 21-3200-020), placed in a cold-mounting mold and allowed to solidify. After solidification, a metallographic image was prepared, and 20 powder particles were randomly selected using a SIGMA300 scanning electron microscope to capture backscattered electron images. The area ratio of Al2Cu in each powder particle was counted as the volume fraction and particle size of Al2Cu.

[0059] Cell diameter and standard deviation: The foamed sample was CT scanned along the thickness direction. A planar image of the thickness center was selected, and ImagePro Plus was used to statistically analyze the average equivalent circle diameter and standard deviation of the cells. The smaller the standard deviation, the more concentrated the cell diameter distribution and the better the uniformity.

[0060] Porosity: After foaming, the sample is CT scanned along the thickness direction. The planar image at the center of the thickness is selected, and ImagePro Plus is used to calculate the area ratio occupied by the cells, which is the porosity.

[0061] Number of cells per unit area: Perform a CT scan along the thickness direction on the foamed sample, select a planar image at the center of the thickness, and use ImagePro Plus to count the number of cells. Divide the number of cells by the total area to obtain the number of cells per unit area.

[0062] Example 1

[0063] A method for preparing foamed aluminum powder alloy, using Al, AlCu50, Si, and Zn as raw materials, and employing a gas atomization powder preparation device to prepare the foamed aluminum powder alloy;

[0064] The gas atomization powder making equipment uses a melting temperature of 100K and a gas-liquid mass flow rate ratio of 1%; the nitrogen pressure in the gas atomization powder making equipment is 3MPa; and the nozzle orifice diameter is 0.8mm.

[0065] The obtained foaming powder aluminum alloy is an Al-Si-Cu-Zn alloy, wherein the Si content is 5wt.%, the Cu content is 25wt.%, the Zn content is 10wt.%, the volume fraction of Al2Cu is 25%, and the particle size of Al2Cu is 1μm; the solid-liquid phase difference of the foaming powder aluminum alloy is 51℃, and the melting temperature is 530℃.

[0066] Comparative Example 1

[0067] A method for preparing powdered aluminum alloy for foaming is basically the same as in Example 1, except that the nitrogen pressure in the gas atomization powder preparation equipment is 2 MPa.

[0068] The volume fraction of Al2Cu in the prepared foamed aluminum alloy is 27%, and the particle size of Al2Cu is 3μm.

[0069] Comparative Example 2

[0070] A method for preparing powdered aluminum alloy for foaming is basically the same as in Example 1, except that the nitrogen pressure in the gas atomization powder preparation equipment is 7 MPa.

[0071] The volume fraction of Al2Cu in the prepared foamed aluminum alloy is 10%, and the particle size of Al2Cu is 0.4 μm.

[0072] Comparative Example 3

[0073] A method for preparing powdered aluminum alloy for foaming is basically the same as in Example 1, except that the nozzle orifice diameter is 0.6 mm.

[0074] The volume fraction of Al2Cu in the prepared foamed aluminum alloy is 11%, and the particle size of Al2Cu is 0.5 μm.

[0075] Comparative Example 4

[0076] A method for preparing powdered aluminum alloy for foaming is basically the same as in Example 1, except that the nozzle orifice diameter is 1.3 mm.

[0077] The volume fraction of Al2Cu in the prepared foamed aluminum alloy was 26%, and the particle size of Al2Cu was 3.6 μm.

[0078] Example 2

[0079] A method for preparing foamed aluminum powder alloy, using Al, AlCu50, Si, and Zn as raw materials, and employing a gas atomization powder preparation device to prepare the foamed aluminum powder alloy;

[0080] The gas atomization powder making equipment uses a melting temperature of 135K and a gas-liquid mass flow rate ratio of 2%; the nitrogen pressure in the gas atomization powder making equipment is 4.5MPa; and the nozzle orifice diameter is 1mm.

[0081] The obtained foaming powder aluminum alloy is an Al-Si-Cu-Zn alloy, wherein the Si content is 7wt.%, the Cu content is 10wt.%, the Zn content is 9wt.%, the volume fraction of Al2Cu is 17%, and the particle size of Al2Cu is 0.7μm; the solid-liquid phase difference of the foaming powder aluminum alloy is 62℃, and the melting temperature is 559℃.

[0082] Example 3

[0083] A method for preparing foamed aluminum powder alloy, using Al, AlCu50, Si, and Zn as raw materials, and employing a gas atomization powder preparation device to prepare the foamed aluminum powder alloy;

[0084] The gas atomization powder making equipment uses a melting temperature of 170K and a gas-liquid mass flow rate ratio of 2.5%; the nitrogen pressure in the gas atomization powder making equipment is 5MPa; and the nozzle orifice diameter is 1mm.

[0085] The obtained foaming powder aluminum alloy is an Al-Si-Cu-Zn alloy, wherein the Si content is 6 wt.%, the Cu content is 18 wt.%, the Zn content is 5 wt.%, the volume fraction of Al2Cu is 20%, and the particle size of Al2Cu is 0.9 μm; the solid-liquid phase difference of the foaming powder aluminum alloy is 40℃, and the melting temperature is 546℃.

[0086] Example 4

[0087] A method for preparing foamed aluminum powder alloy, using Al, AlCu50, Si, and Zn as raw materials, and employing a gas atomization powder preparation device to prepare the foamed aluminum powder alloy;

[0088] The gas atomization powder making equipment uses a melting temperature of 200K and a gas-liquid mass flow rate ratio of 3%; the nitrogen pressure in the gas atomization powder making equipment is 6MPa; and the nozzle orifice diameter is 1.2mm.

[0089] The obtained foaming powder aluminum alloy is an Al-Si-Cu-Zn alloy, wherein the Si content is 9 wt.%, the Cu content is 5 wt.%, the Zn content is 8 wt.%, the volume fraction of Al2Cu is 12%, and the particle size of Al2Cu is 0.5 μm; the solid-liquid phase difference of the foaming powder aluminum alloy is 63℃, and the melting temperature is 564℃.

[0090] Example 5

[0091] A method for preparing foamed aluminum powder alloy, using Al, AlCu50 and Si as raw materials, and employing a gas atomization powder preparation device to prepare the foamed aluminum powder alloy;

[0092] The gas atomization powder making equipment uses a melting temperature of 100K and a gas-liquid mass flow rate ratio of 1%; the nitrogen pressure in the gas atomization powder making equipment is 3MPa; and the nozzle orifice diameter is 0.8mm.

[0093] The obtained foaming powder aluminum alloy is an Al-Si-Cu alloy, wherein the Si content is 5wt.%, the Cu content is 25wt.%, the volume fraction of Al2Cu is 22%, and the particle size of Al2Cu is 1μm; the solid-liquid phase difference of the foaming powder aluminum alloy is 14℃, and the melting temperature is 539℃.

[0094] Example 6

[0095] A method for preparing foamed aluminum powder alloy, using Al, AlCu50 and Si as raw materials, and employing a gas atomization powder preparation device to prepare the foamed aluminum powder alloy;

[0096] The gas atomization powder making equipment uses a melting temperature of 200K and a gas-liquid mass flow rate ratio of 3%; the nitrogen pressure in the gas atomization powder making equipment is 6MPa; and the nozzle orifice diameter is 1.2mm.

[0097] The obtained foaming powder aluminum alloy is an Al-Si-Cu alloy, wherein the Si content is 9wt.%, the Cu content is 5wt.%, the volume fraction of Al2Cu is 11%, and the particle size of Al2Cu is 0.5μm; the solid-liquid phase difference of the foaming powder aluminum alloy is 60℃, and the melting temperature is 585℃.

[0098] In the following Examples 7-12 and Comparative Examples 5-9 of the present invention, the aluminum lower substrate and aluminum upper substrate used are both standard alloy AA3003, and the foaming agent is TiH2.

[0099] Example 7

[0100] A method for preparing small-pore aluminum foam composite material, the specific steps of which are as follows:

[0101] (1) Preparation of foaming powder;

[0102] The foaming powder aluminum alloy of Example 1 was mixed evenly with a foaming agent to obtain foaming powder;

[0103] The foaming agent content in the foaming powder is 0.3 wt.%.

[0104] (2) Powder briquettes;

[0105] The foamed powder obtained in step (1) is pressed into blocks under a pressure of 200 MPa to obtain powder blocks;

[0106] (3) Hot rolling to prepare foamed preforms;

[0107] The powder block obtained in step (2) is assembled in the aluminum lower substrate with square groove so that the powder block just fills the square groove. Then the aluminum upper substrate is placed on the aluminum lower substrate filled with powder block so that the square groove is completely covered by the upper substrate. The foamed preform is obtained by hot rolling at 450°C.

[0108] Of these, the deformation rate for hot rolling is 70%.

[0109] (4) The foamed preform obtained in step (3) is preheated at 450°C and kept at that temperature for 30 minutes. Then it is foamed at 630°C for 3 minutes. After foaming, it is cooled to 500°C at a cooling rate of 60°C / min to obtain small-pore aluminum foam composite material.

[0110] The final small-pore aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on both sides thereon; the foam layer has a pore diameter of 1.22 mm, a standard deviation of 0.4, a porosity of 52%, and a pore count of 1.1 pores / mm². 2 .

[0111] Comparative Example 5

[0112] A method for preparing a foamed aluminum composite material is basically the same as in Example 7, except that the deformation of hot rolling in step (3) is 68%.

[0113] The final aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on either side of it; the foam layer has a pore diameter of 3.02 mm, a standard deviation of 2.5, a porosity of 30%, and a pore count of 0.5 pores / mm². 2 .

[0114] Comparing Comparative Example 5 and Example 7, it can be found that the cell diameter and standard deviation of the cell layer increase, while the porosity decreases. This is because the hot rolling deformation of Comparative Example 5 is less than 70%, and the pores cannot be completely healed, which can easily lead to problems such as uneven cell size during foaming.

[0115] Comparative Example 6

[0116] A method for preparing a foamed aluminum composite material is basically the same as in Example 7, except that the foaming powdered aluminum alloy of Example 1 is replaced with the foaming powdered aluminum alloy of Comparative Example 1.

[0117] The final aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on either side of it; the foam layer has a pore diameter of 2.11 mm, a standard deviation of 1.2, a porosity of 50%, and a pore count of 0.7 pores / mm². 2 .

[0118] Comparing Comparative Example 6 and Example 7, it can be found that the pore diameter and standard deviation of the foam layer increase. This is because the high-pressure gas pressure in Comparative Example 1 is low, the gas flow rate is low, the melt is not fully broken up, the powder particle size is large, the specific surface area is small, the cooling rate is low, and the growth time of the Al2Cu phase is prolonged, resulting in the coarsening of the Al2Cu phase and the formation of a continuous network structure. During foaming, the nucleation density of bubbles decreases, and the pore size becomes coarser and unevenly distributed.

[0119] Comparative Example 7

[0120] A method for preparing a foamed aluminum composite material is basically the same as in Example 7, except that the foaming powdered aluminum alloy of Example 1 is replaced with the foaming powdered aluminum alloy of Comparative Example 2.

[0121] The final aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on either side of it; the foam layer has a pore diameter of 1.86 mm, a standard deviation of 1, a porosity of 51%, and a pore count of 0.8 pores / mm². 2 .

[0122] Comparing Comparative Example 7 and Example 7, it can be found that the pore diameter and standard deviation of the bubble layer increase. This is because the high pressure of the gas in Comparative Example 2 is higher, the gas flow rate is too high, the melt is excessively broken into fine powder, the specific surface area increases dramatically, the cooling rate is extremely fast, atomic diffusion is significantly suppressed, the Al2Cu phase is difficult to nucleate, too few Al2Cu phases are formed, the Al2Cu phase distribution is sparse, the heterogeneous nucleation ability is weak, and the bubble nucleation mainly depends on the spontaneous nucleation of the melt, resulting in uneven pore size distribution and a larger average pore size.

[0123] Comparative Example 8

[0124] A method for preparing a foamed aluminum composite material is basically the same as in Example 7, except that the foaming powdered aluminum alloy of Example 1 is replaced with the foaming powdered aluminum alloy of Comparative Example 3.

[0125] The final aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on either side of it; the foam layer has a pore diameter of 1.92 mm, a standard deviation of 1.1, a porosity of 49%, and a pore count of 0.7 pores / mm². 2 .

[0126] Comparing Comparative Example 8 and Example 7, it can be found that the bubble diameter and standard deviation of the bubble layer increase. This is because the nozzle orifice of Comparative Example 3 is smaller, generating smaller droplets, which accelerates the cooling rate, inhibits the growth of Al2Cu phase and reduces its volume fraction. The Al2Cu phase is sparsely distributed, with weak heterogeneous nucleation ability. Bubble nucleation mainly depends on spontaneous nucleation of the melt, resulting in uneven pore size distribution and a larger average pore size.

[0127] Comparative Example 9

[0128] A method for preparing a foamed aluminum composite material is basically the same as in Example 7, except that the foaming powdered aluminum alloy of Example 1 is replaced with the foaming powdered aluminum alloy of Comparative Example 4.

[0129] The final aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on either side of it; the foam layer has a pore diameter of 2.33 mm, a standard deviation of 1.2, a porosity of 51%, and a pore count of 0.6 pores / mm². 2 .

[0130] Comparing Comparative Example 9 and Example 7, it can be found that the bubble diameter and standard deviation of the bubble layer increase. This is because the larger nozzle orifice of Comparative Example 4 will produce larger droplets, prolong the cooling time, promote the coarsening of the Al2Cu phase, and form a continuous network structure. During foaming, the bubble nucleation density decreases, and the pore size coarsens and the distribution is uneven.

[0131] Example 8

[0132] A method for preparing small-pore aluminum foam composite material, the specific steps of which are as follows:

[0133] (1) Preparation of foaming powder;

[0134] The foaming powdered aluminum alloy of Example 2 was mixed evenly with a foaming agent to obtain foaming powder;

[0135] The foaming agent content in the foaming powder is 0.5 wt.%.

[0136] (2) Powder briquettes;

[0137] The foamed powder obtained in step (1) is pressed into blocks under a pressure of 250 MPa to obtain powder blocks;

[0138] (3) Hot rolling to prepare foamed preforms;

[0139] The powder block obtained in step (2) is assembled in the aluminum lower substrate with square groove so that the powder block just fills the square groove. Then the aluminum upper substrate is placed on the aluminum lower substrate filled with powder block so that the square groove is completely covered by the upper substrate. The foamed preform is obtained by hot rolling at 470°C.

[0140] Of these, the deformation rate for hot rolling is 75%.

[0141] (4) The foamed preform obtained in step (3) is preheated at 470°C and kept at that temperature for 20 minutes. Then it is foamed at 689°C for 5 minutes. After foaming, it is cooled to 500°C at a cooling rate of 70°C / min to obtain the foamed aluminum composite material.

[0142] The final small-pore aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on both sides thereon; the foam layer has a pore diameter of 1.03 mm, a standard deviation of 0.3, a porosity of 60%, and a pore count of 1.4 pores / mm². 2 .

[0143] Example 9

[0144] A method for preparing small-pore aluminum foam composite material, the specific steps of which are as follows:

[0145] (1) Preparation of foaming powder;

[0146] The foaming powder aluminum alloy of Example 3 was mixed evenly with a foaming agent to obtain foaming powder;

[0147] The foaming agent content in the foaming powder is 0.8 wt.%.

[0148] (2) Powder briquettes;

[0149] The foamed powder obtained in step (1) is pressed into blocks under a pressure of 300 MPa to obtain powder blocks;

[0150] (3) Hot rolling to prepare foamed preforms;

[0151] The powder block obtained in step (2) is assembled in the aluminum lower substrate with square groove so that the powder block just fills the square groove. Then the aluminum upper substrate is placed on the aluminum lower substrate filled with powder block so that the square groove is completely covered by the upper substrate. The foamed preform is obtained by hot rolling at a temperature of 485°C.

[0152] Of these, the deformation rate for hot rolling is 80%.

[0153] (4) The foamed preform obtained in step (3) is preheated at 490°C and kept at that temperature for 15 minutes. Then it is foamed at 716°C for 6 minutes. After foaming, it is cooled to 500°C at a cooling rate of 80°C / min to obtain the foamed aluminum composite material.

[0154] The final small-pore aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on both sides thereon; the foam layer has a pore diameter of 0.78 mm, a standard deviation of 0.3, a porosity of 65%, and a pore count of 1.8 pores / mm². 2 .

[0155] Example 10

[0156] A method for preparing small-pore aluminum foam composite material, the specific steps of which are as follows:

[0157] (1) Preparation of foaming powder;

[0158] The foaming powder aluminum alloy of Example 4 was mixed evenly with a foaming agent to obtain foaming powder;

[0159] The foaming agent content in the foaming powder is 1.2 wt.%.

[0160] (2) Powder briquettes;

[0161] The foamed powder obtained in step (1) is pressed into blocks under a pressure of 400 MPa to obtain powder blocks;

[0162] (3) Hot rolling to prepare foamed preforms;

[0163] The powder block obtained in step (2) is assembled in the aluminum lower substrate with square groove so that the powder block just fills the square groove. Then the aluminum upper substrate is placed on the aluminum lower substrate filled with powder block so that the square groove is completely covered by the upper substrate. The foamed preform is obtained by hot rolling at 500°C.

[0164] Of these, the deformation rate for hot rolling is 85%.

[0165] (4) The foamed preform obtained in step (3) is preheated at 500°C and kept at that temperature for 10 minutes. Then it is foamed at 764°C for 10 minutes. After foaming, it is cooled to 500°C at a cooling rate of 100°C / min to obtain the foamed aluminum composite material.

[0166] The final small-pore aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on both sides thereon; the foam layer has a pore diameter of 0.54 mm, a standard deviation of 0.2, a porosity of 70%, and a pore count of 2.3 pores / mm². 2 .

[0167] Example 11

[0168] A method for preparing a small-pore aluminum foam composite material is basically the same as in Example 7, except that the aluminum powder alloy for foaming in Example 1 is replaced with the aluminum powder alloy for foaming in Example 5.

[0169] The final small-pore aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on both sides thereon; the foam layer has a pore diameter of 1.75 mm, a standard deviation of 0.6, a porosity of 46%, and a pore count of 0.7 pores / mm². 2 .

[0170] Example 12

[0171] A method for preparing a small-pore aluminum foam composite material is basically the same as in Example 10, except that the aluminum powder alloy for foaming in Example 4 is replaced with the aluminum powder alloy for foaming in Example 6.

[0172] The final small-pore aluminum foam composite material consists of a foam layer and upper and lower substrate layers located on both sides thereon; the foam layer has a pore diameter of 1.82 mm, a standard deviation of 0.7, a porosity of 43%, and a pore count of 0.5 pores / mm². 2 .

Claims

1. A powder aluminum alloy for foaming, characterized by: The Al-Si-Cu alloy or Al-Si-Cu-Zn alloy contains 5-9 wt.% of Si and 5-25 wt.% of Cu. The volume fraction of Al2Cu is 12-25%, and the particle size of Al2Cu is less than or equal to 1 μm.

2. A powder aluminum alloy for a foam according to claim 1, characterized by The content of Zn is greater than or equal to 5 wt.%, and the melting temperature of the foaming powder aluminum alloy is 530-564 ℃.

3. A method of producing a powder aluminum alloy for foaming according to claim 1 or 2, characterized in that: The foaming powder aluminum alloy is prepared by using a gas atomization powdering device. The nitrogen pressure in the gas atomization powdering device is 3-6 MPa. The nozzle aperture is 0.8-1.2 mm.

4. The method of claim 3, wherein the powder aluminum alloy for foaming is prepared by the steps of: preparing a molten aluminum alloy; and adding a foaming agent to the molten aluminum alloy to prepare a foaming powder aluminum alloy. The smelting temperature of the gas atomization powdering device is 100-200 K, and the gas-liquid mass flow rate ratio is 1-3%.

5. A method for producing a foamed aluminum composite material using the foaming powder aluminum alloy according to claim 1 or 2, characterized by The method comprises the following steps: (1) preparation of foaming powder; The foaming powder aluminum alloy is mixed with a foaming agent to obtain foaming powder; (2) powder briquetting; The foaming powder obtained in step (1) is briquetted to obtain a powder briquette; (3) hot rolling to prepare a foaming preform; The powder briquette obtained in step (2) is assembled in an aluminum lower substrate with a square groove, the powder briquette is just filled in the square groove, an aluminum upper substrate is covered on the aluminum lower substrate filled with the powder briquette, the square groove is completely covered by the upper substrate, and a foaming preform is obtained by hot rolling; the deformation amount of hot rolling is greater than or equal to 70%; (4) foaming of the foaming preform obtained in step (3) to prepare a foamed aluminum composite material.

6. The method for preparing a foamed aluminum composite material according to claim 5, characterized in that, The content of the foaming agent in the foaming powder in step (1) is 0.3-1.2 wt.%.

7. The method for preparing a foamed aluminum composite material according to claim 5, characterized in that, The pressure for briquetting in step (2) is 200-400 MPa.

8. The method for preparing a foamed aluminum composite material according to claim 5, characterized in that, In step (4), the foaming temperature is higher than the melting temperature of the foaming powder aluminum alloy by 100-200 ℃, the foaming time is 3-10 min, and the cooling rate after foaming is 60-100 ℃ / min.

9. A small-pore foamed aluminum composite material prepared by the method according to any one of claims 5 to 8, characterized in that: The small-pore-diameter aluminum foam composite material comprises a foam layer and upper and lower substrate layers on both sides of the foam layer; the foam layer has a pore diameter of 0.54-1.24 mm, a porosity of greater than 50%, and a pore number per unit area of 0.9-2.3 pores / mm 2 .

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