1. An aluminum alloy sandwich panel comprises a foam aluminum alloy core layer and an aluminum alloy panel,

wherein the foamed aluminum alloy core layer comprises

Based on the total weight of the foamed aluminum alloy core layer,

6-11% by weight of Si,

0-5% by weight of Cu,

0 to 3% by weight of Mn,

0-4% by weight of Zn, in the form of a powder,

0-0.8% by weight of Mg,

the balance of Al and inevitable impurities;

the melting point of the aluminum alloy panel is above 645 ℃.

2. The sandwich panel of claim 1, wherein the foamed aluminum alloy core layer comprises

Based on the total weight of the foamed aluminum alloy core layer,

7.0-10.7% by weight of Si, and/or

0-4.5 wt.% Cu, and/or

0-2% by weight of Mn, and/or

0-3% by weight of Zn, and/or

0-0.6 wt.% Mg.

3. The sandwich panel of claim 1 or 2, wherein the foamed aluminium alloy core layer further comprises Ca in an amount of 0.25 to 3 wt. -%, preferably 0.5 to 2.5 wt. -%, based on the total weight of the foamed aluminium alloy core layer; and/or

The foamed aluminum alloy core layer further comprises Sr, wherein the Sr content is 40-400ppm based on the total weight of the foamed aluminum alloy core layer; and/or

The foamed aluminum alloy core layer also includes Ti in an amount of 1.0 to 1.5 wt.% based on the total weight of the foamed aluminum alloy core layer.

4. The sandwich panel of one of claims 1 to 3, wherein,

the interface bonding rate of the foamed aluminum alloy core layer and the aluminum alloy panel is more than 95%, preferably more than 99%, and more preferably 100%.

5. The sandwich panel of any of claims 1 to 4, wherein,

the foamed aluminum alloy core layer has a melting point of about 615 ℃ or less, and/or

The melting point of the aluminum alloy panel is 645-.

6. The sandwich panel of any of claims 1 to 5, wherein,

the foamed aluminum alloy core layer is of a porous structure, and the average equivalent pore diameter of the foamed aluminum alloy core layer is 2-8mm, preferably 2.5-7.5 mm.

7. The sandwich panel of any of claims 1-6, wherein,

the pore area of the average equivalent pore diameter range of +/-20% in the foamed aluminum alloy core layer accounts for more than 50% of the total pore area, and preferably 60% -85%.

8. The sandwich panel of one of claims 1 to 7, wherein,

the porosity of the foamed aluminium alloy core layer is 70-90%, and/or

The density of the foamed aluminum alloy core layer is 0.27-0.81g/cm³。

9. The sandwich panel of any of claims 1-8, wherein,

the aluminum alloy panel is 3 series aluminum alloy or 6 series aluminum alloy.

10. The sandwich panel of one of claims 1 to 9, wherein,

the thickness of the aluminum alloy sandwich plate is 5-35 mm.

11. The sandwich panel of one of claims 1 to 10, wherein,

and aluminum alloy panels are respectively arranged on two sides of the foamed aluminum alloy core layer, wherein the aluminum alloy panels are in metallurgical connection with the aluminum alloy core layer.

12. The sandwich panel of one of claims 1 to 11, wherein,

obtaining the aluminum alloy sandwich panel through foaming treatment, wherein the foaming temperature is higher than the melting point of the foamed aluminum alloy core layer, and the foaming temperature is lower than the melting point of the aluminum alloy panel.

13. The sandwich panel of one of claims 1 to 12, wherein,

the prefabricated body of the foamed aluminum alloy core layer is prepared by a liquid phase method.

14. A method of making a sandwich panel according to any one of claims 1 to 13, comprising the steps of:

(1) preparing an aluminum alloy melt of the foam aluminum alloy core layer,

(2) pouring the aluminum alloy melt into a mold for molding, and performing pressure maintaining solidification to obtain a prefabricated body of the foamed aluminum alloy core layer,

(3) rolling and compounding the prefabricated body and the initial aluminum alloy panel to obtain a composite plate,

(4) foaming the composite board;

wherein the foaming temperature is 620-640 ℃.

15. The method of claim 14, wherein,

the step (1) comprises the following steps:

(1.1) adding an adhesion promoter to the initial aluminum alloy melt of the foamed aluminum alloy core layer,

(1.2) adding a foaming agent to the melt obtained in step (1.1).

16. The method of claim 15, wherein,

in step (1.1), the viscosity increasing agent is Ca; and/or

In the step (1.1), adding an alterant, wherein the alterant is Al-Sr alloy, and the Sr content is 40-400ppm based on the total weight of the initial aluminum alloy melt; and/or

In step (1.2), the foaming agent is present in an amount of 1.0 to 1.5 wt.%, based on the total weight of the initial aluminum alloy melt.

17. The method of any one of claims 14-16,

the initial aluminum alloy melt comprises

Based on the total weight of the initial aluminum alloy melt,

6-11% by weight of Si,

0-5% by weight of Cu,

0 to 3% by weight of Mn,

0-4% by weight of Zn, in the form of a powder,

0-0.8% by weight of Mg,

the balance of Al and inevitable impurities.

18. The method of any one of claims 14-17,

in the step (1.2), the foaming agent is titanium hydride, and the titanium hydride is subjected to heat treatment at 490-540 ℃.

19. The method according to any one of claims 14 to 18, wherein, in step (2),

the shaping is extrusion, and/or

The pressure for maintaining the pressure is 3-80MPa, preferably 5-50 MPa.

20. The method of any one of claims 14-19, wherein,

the total rolling reduction rate of the rolling in the step (3) is more than 50%, preferably 50-95%.

21. The method of any one of claims 14-20, wherein,

the foaming in step (4) is restricted location foaming.

22. A method according to any one of claims 14 to 21, wherein the expansion of the foamed aluminium alloy core layer in step (4) is in the range 200% to 600%, preferably 300% to 520%.

23. An aluminum alloy sandwich panel produced by the method of any one of claims 14 to 22.

Background

The sandwich composite board with the foamed aluminum alloy as the core layer and the aluminum alloy as the panel has the excellent mechanical properties of light weight, high specific stiffness and the like, and also has the functional characteristics of damping, vibration suppression, energy absorption, impact resistance, electromagnetic shielding and the like, so that the foamed aluminum alloy sandwich board is widely applied to the fields of new energy automobiles, high-speed trains, subway trains and the like, and is an effective means for lightening the automobile body and reducing the energy consumption.

The combination mode and the combination strength of the foamed aluminum alloy core layer and the surface aluminum panel have important influence on the mechanical property and the energy absorption capacity of the sandwich panel, and also relate to whether the sandwich panel can be further processed and formed and welded with other aluminum parts by adopting a welding mode.

The foamed aluminum alloy core layer and the aluminum alloy panel are typically bonded using an adhesive. Such bonds tend to have relatively low interfacial strength, are prone to cracking after the sandwich panel is deformed, and are difficult to secondary process. And the adhesive of the bonding part is easy to age, so that the service life of the sandwich panel is limited. For metallurgical connection, interface metallurgical bonding can be internationally realized at present, and the method for large-scale production is a powder metallurgy method. The process comprises the steps of mixing aluminum powder and a foaming agent at normal temperature, preparing a prefabricated body through a series of complex processes such as cold pressing, hot pressing, rolling and the like, and preparing the foamed aluminum sandwich board through foaming. The method has poor uniformity of the pore structure and is limited to a certain extent by high raw material cost, complex process, low production efficiency, expensive selling price and difficult popularization and application.

Disclosure of Invention

In one aspect, the present invention relates to an aluminum alloy sandwich panel comprising a foamed aluminum alloy core layer and an aluminum alloy panel, wherein the foamed aluminum alloy core layer comprises, based on the total weight of the foamed aluminum alloy core layer, 6 to 11 wt.% Si, 0 to 5 wt.% Cu, 0 to 3 wt.% Mn, 0 to 4 wt.% Zn, 0 to 0.8 wt.% Mg, and the balance Al and unavoidable impurities; the melting point of the aluminum alloy panel is above 645 ℃.

In one embodiment, in the sandwich panel of the present invention, the foamed aluminium alloy core layer comprises 7.0-10.7 wt.% Si, and/or 0-4.5 wt.% Cu, and/or 0-2 wt.% Mn, and/or 0-3 wt.% Zn, and/or 0-0.6 wt.% Mg, based on the total weight of the foamed aluminium alloy core layer.

In a preferred embodiment, in the sandwich panel of the invention, the foamed aluminium alloy core layer further comprises Ca in an amount of 0.25 to 3 wt. -%, preferably 0.5 to 2.5 wt. -%, based on the total weight of the foamed aluminium alloy core layer; and/or the foamed aluminium alloy core layer further comprises Sr in an amount of 40-400ppm, based on the total weight of the foamed aluminium alloy core layer; and/or the foamed aluminum alloy core layer further comprises Ti in an amount of 1.0 to 1.5 wt.%, based on the total weight of the foamed aluminum alloy core layer.

In a preferred embodiment, the sandwich panel of the present invention has an interfacial bonding ratio of the foamed aluminum alloy core layer to the aluminum alloy face sheet of 95% or more. In a more preferred embodiment, the sandwich panel of the present invention has an interfacial bonding ratio of the foamed aluminum alloy core layer to the aluminum alloy face sheet of 99% or more. In a particularly preferred embodiment, the sandwich panel of the present invention has an interfacial bond of 100% between the foamed aluminum alloy core layer and the aluminum alloy face sheet.

In another embodiment, the sandwich panel of the present invention wherein the foamed aluminum alloy core layer has a melting point of about 615 ℃ or less.

In yet another embodiment, the aluminum alloy face sheets in the sandwich panel of the present invention have a melting point of 645-.

In yet another embodiment, the foamed aluminum alloy core layer is a porous structure, and the foamed aluminum alloy core layer has an average equivalent pore size of 2 to 8mm, preferably 2.5 to 7.5 mm.

In yet another embodiment, the area of the cells in the range of the average equivalent pore diameter of the foamed aluminum alloy core layer ± 20% accounts for more than 50% of the total area of the cells, preferably from 60% to 85%.

In one embodiment, the foamed aluminum alloy core layer has a porosity of 70 to 90%, and/or

The density of the foamed aluminum alloy core layer is 0.27-0.81g/cm³。

In another embodiment, the aluminum alloy panel is a 3-series aluminum alloy or a 6-series aluminum alloy.

In yet another embodiment, the aluminum alloy sandwich panel has a thickness of 5 to 35 mm.

In yet another embodiment, aluminum alloy face sheets are disposed on each side of the foamed aluminum alloy core layer, wherein the aluminum alloy face sheets are metallurgically joined to the aluminum alloy core layer.

In one embodiment, the aluminum alloy sandwich panel is obtained by a foaming process, wherein the foaming temperature is higher than the melting point of the foamed aluminum alloy core layer and the foaming temperature is lower than the melting point of the aluminum alloy panel.

In another embodiment, the preform for the foamed aluminum alloy core layer is prepared by a liquid phase process.

In another aspect, the present invention relates to a method of making a sandwich panel of the present invention comprising the steps of: (1) preparing an aluminum alloy melt of a foam aluminum alloy core layer, (2) pouring the aluminum alloy melt into a mold for molding and pressure maintaining solidification to obtain a preform of the foam aluminum alloy core layer, (3) rolling and compounding the preform and an initial aluminum alloy panel to obtain a composite plate, and (4) foaming the composite plate; wherein the foaming temperature is 620-640 ℃.

In one embodiment, step (1) comprises the steps of: (1.1) adding a tackifier to the initial aluminium alloy melt of the foamed aluminium alloy core layer, (1.2) adding a foaming agent to the melt obtained in step (1.1).

In another embodiment, in step (1.1), the viscosifier is Ca; and/or

In the step (1.1), adding an alterant, wherein the alterant is Al-Sr alloy, and the Sr content is 40-400ppm based on the total weight of the initial aluminum alloy melt; and/or

In step (1.2), the foaming agent is present in an amount of 1.0 to 1.5 wt.%, based on the total weight of the initial aluminum alloy melt.

In yet another embodiment, the initial aluminum alloy melt comprises 6 to 11 wt.% Si, 0 to 5 wt.% Cu, 0 to 3 wt.% Mn, 0 to 4 wt.% Zn, 0 to 0.8 wt.% Mg, and the balance Al and unavoidable impurities, based on the total weight of the initial aluminum alloy melt.

In a further embodiment, in step (1.2), the foaming agent is titanium hydride, which has been subjected to a heat treatment at 490-540 ℃.

In one embodiment, in step (2), the pressure of the dwell pressure is in the range of from 3 to 80MPa, preferably from 5 to 50 MPa.

In yet another embodiment, the shaping in step (2) is extrusion.

In another embodiment, the rolling in step (3) has a total reduction of 50% or more, preferably 50 to 95%.

In yet another embodiment, the foaming in step (4) is a restricted location foaming.

In yet another embodiment, the expansion of the aluminum alloy core layer after the foaming treatment in step (4) is 200% to 600%, preferably 300% to 520%.

In yet another aspect, the present invention relates to an aluminum alloy sandwich panel made by the method of the present invention.

Drawings

FIG. 1 is a schematic view of a sandwich panel of the present invention;

FIG. 2 is a photograph showing the appearance of a preform in example 1 of the present invention;

FIG. 3 is a photograph showing a cross section of an aluminum alloy sandwich panel in example 1 of the present invention;

FIG. 4 is a photograph showing a cross-section of an aluminum alloy sandwich panel in example 2 of the present invention;

FIG. 5 is a metallographic microscope photograph of an aluminum alloy sandwich panel according to example 1 of the present invention;

FIG. 6 is a metallographic microscope photograph of the aluminum alloy sandwich panel in comparative example 3;

in the figure: 1 represents a foamed aluminium alloy core layer; 2 represents an aluminum alloy panel; 3 represents an air hole; 4 represents a brazing layer; 5. showing the pore walls.

Detailed Description

General definitions and terms

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present application will control.

All percentages, parts, ratios, etc. herein are by weight unless otherwise indicated.

When an amount, concentration, or other value or parameter is expressed in terms of a range, preferred range, or upper preferable numerical value and lower preferable numerical value, it is understood that any range defined by any pair of upper range limits or preferred numerical values in combination with any lower range limits or preferred numerical values is specifically disclosed, regardless of whether the range is specifically disclosed. Unless otherwise indicated, numerical ranges set forth herein are intended to include the endpoints of the ranges, and all integers and fractions within the ranges. For example, "1-8" encompasses 1, 2, 3, 4, 5, 6, 7, 8, as well as any subrange consisting of any two values therein, e.g., 2-6, 3-5.

The expressions "comprising" or similar expressions "including", "containing" and "having" and the like which are synonymous are open-ended and do not exclude additional, unrecited elements, steps or components. The expression "consisting of …" excludes any element, step or ingredient not specified. The expression "consisting essentially of …" means that the scope is limited to the specified elements, steps or components, plus optional elements, steps or components that do not materially affect the basic and novel characteristics of the claimed subject matter. It is to be understood that the expression "comprising" covers the expressions "consisting essentially of …" and "consisting of …".

The term "inevitable impurities" as used herein means other element components not intentionally added or contained in the manufacturing process of the alloy, the other elements being introduced as inevitable impurities. Among other elements, the content of single element is less than or equal to 0.05 weight percent, and the content of total elements is less than or equal to 0.15 weight percent.

The term "about" as used herein may allow for a degree of variation in the value or range, such as within the stated value or range of the stated limit and including within 10%, within 5% or within 1% of the exact value or range.

The terms "optionally" or "optionally" as used herein mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where said event or circumstance occurs and instances where it does not.

The term "one or more" as used herein means 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more.

The terms "3-series aluminum alloy", "6-series aluminum alloy" as used herein are generic alloy designations in the art that are well known to those skilled in the art, such as GB-T3190-2016 wrought aluminum and aluminum alloy chemistries. For example, the 3-series alloy is a series of alloys having aluminum manganese as a main element; the 6-series alloy is a series of alloys using aluminum, silicon and magnesium as main elements. The 3-series alloy herein includes, but is not limited to, 3003 aluminum alloy, 3005 aluminum alloy, 3004 aluminum alloy. The 6-series alloy includes, but is not limited to, 6060 aluminum alloy, 6063 aluminum alloy, 6951 aluminum alloy, 6082 aluminum alloy, or 6061 aluminum alloy.

The "melting point" of an aluminum alloy as referred to herein refers to the temperature at which the aluminum alloy is completely melted into a liquid state.

The term "equivalent pore diameter" as used herein refers to the pore diameter when converted to a circular pore having an area equal to that of an irregularly shaped pore. Herein, the aperture and aperture area are obtained by acquiring an image by a scanner and calculating by ranging software.

The term "foaming" as used herein refers to a process in which a foaming agent decomposes under heating to generate a gas, and the gas expands to foam.

The term "limiting foaming" refers to a foaming process that is performed under conditions that define the location of the foamed material. For example, the upper and lower panels of the aluminum alloy composite panel are positionally restricted by using a foaming mold, and the cavity is filled with the expansion action of liquid foam.

The "heat preservation foaming" refers to a foaming process performed at a certain temperature. For example, a foaming operation carried out while maintaining the temperature at 10 to 30 ℃ higher than the liquidus temperature of the aluminum alloy.

The term "dwell solidification" as used herein refers to a solidification process that is carried out while being maintained under pressure. For example, a solidification process in which the pressure is maintained at 50 MPa.

As used herein, the term "metallurgical bond" refers to the interdiffusion of atoms at the interface of two metals to form a bond.

The term "interfacial bonding ratio" as used herein refers to the ratio of the area of the aluminum alloy sandwich panel in which the core alloy is in direct contact with the two side panels.

Aluminum alloy sandwich panel

The invention relates to an aluminum alloy sandwich panel, which comprises a foamed aluminum alloy core layer and an aluminum alloy panel. The aluminum alloy sandwich panel of the invention can also be called an aluminum panel foamed aluminum sandwich panel.

Wherein the foamed aluminum alloy core layer comprises

Based on the total weight of the foamed aluminum alloy core layer,

6-11% by weight of Si,

0-5% by weight of Cu,

0 to 3% by weight of Mn,

0-4% by weight of Zn, in the form of a powder,

0-0.8% by weight of Mg,

the balance of Al and inevitable impurities.

The melting point of the aluminum alloy panel is above 645 ℃.

The amount of Si in the foamed aluminum alloy core layer is about 6 to 11 weight percent, preferably about 7 to 10.7 weight percent, based on the total weight of the foamed aluminum alloy core layer. Too high Si content is detrimental to rolling and the obtained core layer is prone to cracking during rolling. Too low a Si content will be detrimental to the core layer having a relatively low melting point, making it difficult for the core layer to melt and foam well at the foaming temperature during the foaming process of the core layer.

In the foam aluminum alloy core layer, elements such as Cu, Mn, Zn, Mg and the like can be optionally added. The existence of elements such as Cu, Mn, Zn, Mg and the like is beneficial to the excellent strength of the core layer, and simultaneously, the melting point of the core layer is lower than the foaming temperature. In one embodiment, the Cu content is about 0 to 5 wt.%, preferably about 0 to 4.5 wt.%, based on the total weight of the foamed aluminum alloy core layer. In another embodiment, Mn is present in an amount of about 0 to 3 weight percent, preferably about 0 to 2 weight percent, based on the total weight of the foamed aluminum alloy core layer. In yet another embodiment, the Zn content is about 0-4 wt.%, preferably about 0-3 wt.%, based on the total weight of the foamed aluminum alloy core layer. In yet another embodiment, Mg is present in an amount of about 0 to 0.8 weight percent, preferably about 0 to 0.6 weight percent, based on the total weight of the foamed aluminum alloy core layer.

In one embodiment, the foamed aluminum alloy core layer of the present invention further comprises Ca. The addition of Ca is beneficial to obtaining a foam aluminum alloy core layer with uniform pore size distribution. An excessively high Ca content will make the core layer susceptible to cracking during rolling. In one embodiment, the Ca is present in an amount of about 0.25 to 3 wt.%, preferably about 0.5 to 2.5 wt.%, based on the total weight of the foamed aluminum alloy core layer.

In another embodiment, the foamed aluminum alloy core layer of the present invention further comprises Sr. The addition of Sr helps to make Si particles in the core layer have a smaller size, thereby reducing cracking during rolling to facilitate rolling. In one embodiment, the Sr content is in a range of between about 40 ppm and 400ppm, preferably between about 50ppm and 300ppm, based on the total weight of the foamed aluminum alloy core layer.

In yet another embodiment, the foamed aluminum alloy core layer of the present invention further comprises Ti. Ti is typically added as a blowing agent in the form of a hydride of titanium, so that the core layer of the aluminium alloy is foamed into a foamed aluminium alloy core layer under the action of the blowing agent. In one embodiment, Ti is present in an amount of 1.0 to 1.5 wt.%, such as about 1.2 wt.%, based on the total weight of the foamed aluminum alloy core layer.

The area ratio of the aluminum alloy core layer bonded to the aluminum alloy face sheet is expressed as the interface bonding ratio. In one embodiment, in the aluminum alloy sandwich panel of the present invention, the interfacial bonding rate of the foamed aluminum alloy core layer to the aluminum alloy face sheet is 95% or more. In a preferred embodiment, the interfacial bonding rate of the foamed aluminum alloy core layer to the aluminum alloy panel is 99% or greater. In a more preferred embodiment, the foamed aluminum alloy core layer has an interfacial bond to the aluminum alloy panel of 100%. E.g., 95%, 96%, 97%, 98%, 99%, 100%. The higher interface bonding rate shows that the aluminum alloy core layer and the aluminum alloy panel can be effectively contacted and firmly bonded, so that the aluminum alloy sandwich plate has excellent mechanical properties and is beneficial to further processing and application of the sandwich plate.

In one embodiment, the melting point of the foamed aluminum alloy core layer is below the foaming temperature. The foaming temperature refers to the temperature at which the aluminum alloy core layer can be foamed into a foamed aluminum alloy core layer under the action of the foaming agent. In a particular embodiment, the foamed aluminum alloy core layer has a melting point of less than about 615 ℃, such as about 570-615 ℃.

The foamed aluminum alloy core layer is of a porous structure. In one embodiment, the foamed aluminum alloy core layer has an average equivalent pore size of about 2 to 8mm, preferably about 2.5 to 7.5 mm.

The foamed aluminum alloy core layer of the invention has uniform pore size distribution. In one embodiment, the area of the cells in the foamed aluminium alloy core layer having a pore diameter of the average equivalent pore diameter is more than 50% of the total area of the cells, preferably from 60% to 85%. Specifically, the pore diameter is the average equivalent pore diameter means the pore diameter of pores within ± 20% of the average equivalent pore diameter. In a particular embodiment, the pore area in the range of ± 20% of the average equivalent pore diameter accounts for more than 50%, preferably more than 55%, more preferably more than 60%, for example 60% to 85%, such as 65, 70, 75, 80% of the total pore area. Such a pore size and uniform pore distribution are advantageous for obtaining a sandwich panel having good mechanical strength.

The core layer of the sandwich panel of the present invention has a suitable porosity and density. In yet another embodiment, the foamed aluminum alloy core layer of the present invention has a porosity of about 70 to 90%, preferably about 75 to 87%. In another embodiment, the density of the foamed aluminum alloy core layer of the present invention ranges from about 0.27 to 0.81g/cm³Preferably about 0.4 to 0.70g/cm³。

In one embodiment, the aluminum alloy panel has a melting point above the foaming temperature. Therefore, the aluminum alloy panel can not be melted in the foaming process of the aluminum alloy core layer, and the sandwich board with uniform aperture, good mechanical property and interface strength can be obtained. In one embodiment, the aluminum alloy face sheets of the sandwich panel of the present invention have a melting point of 645 ℃ or greater, preferably 650-. In a preferred embodiment, the aluminum alloy panel is a 3-series aluminum alloy or a 6-series aluminum alloy, such as 3003 aluminum alloy, 3005 aluminum alloy, 3004 aluminum alloy, 6060 aluminum alloy, 6063 aluminum alloy, 6951 aluminum alloy, 6082 aluminum alloy, or 6061 aluminum alloy. The preferred type of aluminium alloy panel is advantageous for obtaining a sandwich panel with good mechanical properties.

In one embodiment, the aluminum alloy panel comprises, based on the total weight of the aluminum alloy panel, 0.2 to 0.7 wt.% Si, 0.02 to 0.4 wt.% Cu, 0 to 1.5 wt.% Mg, 0.05 to 0.3 wt.% Zn, 0.5 to 2 wt.% Mn, 0.2 to 1.5 wt.% Fe, 0 to 0.2 wt.% Cr, 0 to 0.2 wt.% Ti, and the balance aluminum and unavoidable impurities.

In a preferred embodiment, the aluminum alloy panel comprises 0.3 to 0.6 wt.% of Si, 0.05 to 0.3 wt.% of Cu, 0 to 1.3 wt.% of Mg, 0.1 to 0.25 wt.% of Zn, 1.0 to 1.5 wt.% of Mn, 0.5 to 0.9 wt.% of Fe, 0 to 0.1 wt.% of Cr, 0 to 0.1 wt.% of Ti, and the balance aluminum and unavoidable impurities, based on the total weight of the aluminum alloy panel.

In another embodiment, the aluminum alloy panel comprises, based on the total weight of the aluminum alloy panel, 0.1 to 2 wt.% Si, 0 to 0.5 wt.% Cu, 0.3 to 2 wt.% Mg, 0 to 0.3 wt.% Zn, 0 to 2 wt.% Mn, 0.05 to 1.5 wt.% Fe, 0 to 0.5 wt.% Cr, 0 to 0.25 wt.% Ti, and the balance aluminum and unavoidable impurities.

In another preferred embodiment, the aluminum alloy panel comprises 0.2 to 1.3 wt.% Si, 0 to 0.4 wt.% Cu, 0.35 to 1.2 wt.% Mg, 0 to 0.25 wt.% Zn, 0 to 1.0 wt.% Mn, 0.1 to 0.7 wt.% Fe, 0 to 0.35 wt.% Cr, 0 to 0.15 wt.% Ti, and the balance aluminum and unavoidable impurities, based on the total weight of the aluminum alloy panel.

In one embodiment, the aluminum alloy sandwich panel of the present invention has a thickness of about 5 to 35mm, preferably about 8 to 30 mm.

In one embodiment, the aluminum alloy sandwich panel of the present invention is as described in fig. 1. The foamed aluminum alloy core layer 1 is a porous structure and comprises a plurality of pores 3. The two sides of the foamed aluminum alloy core layer 1 are respectively provided with an aluminum alloy panel 2, wherein the aluminum alloy panel 2 and the aluminum alloy core layer 1 are in metallurgical connection. The connection mode enables the sandwich plate to have excellent interface bonding strength.

In another embodiment, the aluminium alloy sandwich panel is obtained by a foaming process. Wherein a foaming temperature is higher than a melting point of the foamed aluminum alloy core layer, and the foaming temperature is lower than a melting point of the aluminum alloy panel. Therefore, in the foaming treatment, the aluminum alloy core layer can be melted and foamed into the foamed aluminum alloy core layer, and the aluminum alloy panel can be kept not to be melted, so that the original form before the foaming treatment is kept.

In yet another embodiment, the preform of the foamed aluminum alloy core layer is prepared by a liquid phase process. The liquid phase method for preparing the prefabricated body of the aluminum alloy core layer means that the aluminum alloy core layer is mixed with a foaming agent after being melted, and then the mixture is subjected to melt casting to prepare the prefabricated body. A foaming agent may thus be included in the preform so that the aluminium alloy core layer is driven to foam into a foamed aluminium alloy core layer during the foaming process. It is different from the powder metallurgy method of mixing aluminum alloy and foaming agent at normal temperature.

Preparation method of aluminum alloy sandwich panel

In another aspect, the present invention relates to a method of making a sandwich panel of the present invention comprising the steps of:

(1) preparing an aluminum alloy melt of the foam aluminum alloy core layer,

(2) pouring the aluminum alloy melt into a mold for molding, and performing pressure maintaining solidification to obtain a prefabricated body of the foamed aluminum alloy core layer,

(3) rolling and compounding the prefabricated body and the initial aluminum alloy panel to obtain a composite plate,

(4) and foaming the composite board.

Step (1) preparing aluminum alloy melt of foam aluminum alloy core layer

In one embodiment, the aluminum alloy melt for preparing the foamed aluminum alloy core layer in step (1) may comprise the steps of:

(1.1) adding an adhesion promoter to the initial aluminum alloy melt of the foamed aluminum alloy core layer,

(1.2) adding a foaming agent to the melt obtained in step (1.1).

Step (1.1)

The initial aluminum alloy melt in step (1.1) contains, based on the total weight of the initial aluminum alloy melt, 6 to 11 wt.% of Si, 0 to 5 wt.% of Cu, 0 to 3 wt.% of Mn, 0 to 4 wt.% of Zn, 0 to 0.8 wt.% of Mg, and the balance Al and inevitable impurities. The function and preferred content of each element are as described above.

In one embodiment, the adhesion promoter is Ca metal. The addition of Ca metal is advantageous in that the melt has a suitable viscosity, so that the formation of uniform pore size is facilitated in the foaming process. The content of Ca should not be too high, which is convenient for rolling the core layer. In a particular embodiment, the Ca is present in an amount of about 0.25 to 3 wt.%, preferably about 0.5 to 2.5 wt.%, based on the total weight of the initial aluminum alloy melt.

In another embodiment, a modifier may also be added to the initial aluminum alloy melt prior to the addition of the adhesion promoter. The addition of the alterant is beneficial to ensure that the particles in the core layer have smaller sizes, thereby reducing the cracking in the rolling process and facilitating the rolling. In a preferred embodiment, the modifier is an Al-Sr alloy, wherein the Sr content is in the range of about 40 to 400ppm, preferably about 50 to 300ppm, based on the total weight of the initial aluminum alloy melt. In another embodiment, the alterant is an Al-Sr alloy, wherein the Sr content is between about 5-15 wt.%, such as about 10 wt.%, based on the total weight of the Al-Sr alloy. In yet another embodiment, the temperature of the aluminum alloy melt after the modification treatment is about 660-750 ℃.

Step (1.2)

In one embodiment, the blowing agent in step (1.2) is titanium hydride.

The pretreatment of the foaming agent can raise the thermal decomposition temperature of the foaming agent, so that the titanium hydride has a slower foaming effect or the decomposition of the foaming agent is slowed down when being mixed with the melt obtained in the step (1.1), thereby obtaining a preform with fewer pores, and the foaming can be concentrated in the foaming treatment of the composite board in the step (4), thereby obtaining a core layer with uniform distribution of the pore size.

In a preferred embodiment, the titanium hydride is pretreated at 490-540 ℃, for example at about 490, 500, 520, 540 ℃.

In one embodiment, the treatment time of the titanium hydride is from 30 to 120min, preferably from 40 to 100 min.

In one embodiment, the particle size of the blowing agent is 200-300 mesh. Such a particle size is advantageous in that the core layer obtains a uniform pore size during foaming.

In one embodiment, the titanium hydride is present in an amount of 1.0 to 1.5 weight percent, such as 1.2 weight percent, based on the total weight of the initial aluminum alloy melt. Too low a blowing agent content is not conducive to obtaining a foamed aluminum alloy core layer with good expansion. Too high a blowing agent content tends to make it difficult to disperse in the melt, or too many bubbles are generated by its decomposition due to too much blowing agent, resulting in the generation of bubbles in the preform.

In one embodiment, the temperature of the melt is maintained at 620-660 ℃ during the addition of the blowing agent in step (1.2). Such a temperature is advantageous in reducing decomposition of the titanium hydride during the stirring and mixing. The higher expansion ratio can be obtained when the rolled preform is foamed at a constant temperature (limited-position foaming), and the melt can still have certain fluidity when being poured into a mold subsequently.

In one embodiment, the melt may be stirred at high speed after the addition of the foaming agent in step (1), particularly step (1.2), to reduce the generation of bubbles in the melt. In one embodiment, the stirring speed is about 800-3000rpm, such as about 1500-3000 rpm. The stirring time is about 1-15min, for example about 3-6 min.

Step (2) pouring the aluminum alloy melt into a mold for molding and carrying out pressure maintaining solidification to obtain a foamed aluminum alloy core layer Of a preform

The molding in the step (2) is preferably extrusion molding. The method is beneficial to obtaining large-scale flat prefabricated bodies, reduces subsequent surface processing procedures such as a milling machine and the like, and is also beneficial to ensuring that the prefabricated bodies are not easy to crack in the subsequent rolling process.

And (3) the pressure maintaining solidification in the step (2) is one of important factors for preparing the prefabricated body of the aluminum alloy sandwich plate. It is advantageous to keep the pressure constant during the solidification of the preform, i.e., to perform the dwell solidification operation, for obtaining a preform having fewer air holes. The pressure is kept unchanged in the solidification process of the preform, so that the defects of small bubbles and the like in the preform caused by the decomposition of a foaming agent in the solidification process of the aluminum liquid can be reduced, the density of a core layer of the preform is high, the aperture is uniform, the expansion rate is high, and the deformation requirement of rolling compounding can be met. Compared with the prior art, the natural cooling solidification cannot achieve the effect, can not reduce the generation of small bubbles in the prefabricated body in the solidification process, is not beneficial to obtaining a prefabricated body core layer with high density, uniform aperture and high expansion rate, and is more beneficial to the subsequent rolling and compounding of the prefabricated body.

In one embodiment, the pressure of the dwell solidification is from about 3 to 80MPa, preferably from 5 to 50MPa, for example about 5, 10, 20, 30, 40, 50 MPa.

In one embodiment, the manner of forming and holding pressure in step (2) may be extrusion casting, liquid die forging, or a combination thereof.

In one embodiment, the mold in step (2) may be preheated, for example to 450 ℃. sup.550 ℃. In another embodiment, the mold in step (2) may further comprise a cooling device, for example, cooling with cooling water.

Step (3) rolling and compounding the prefabricated body and the initial aluminum alloy panel to obtain the composite board

The rolling in step (3) is usually carried out at a temperature of 400-460 ℃. In one embodiment, prior to rolling, preheating may also be performed. For example, the temperature of preheating is 400-450 ℃. The preheating time is at least 30 min.

And (3) rolling and compounding the upper initial aluminum alloy panel, the lower initial aluminum alloy panel and the preform, or rolling and compounding the upper initial aluminum alloy panel, the lower initial aluminum alloy panel and the preform by using one initial aluminum alloy panel. Such rolling helps to reduce cracking of the preform and panel during rolling. For example, an initial aluminum alloy panel is bent to a U-shape in vertical cross-section, the preform is placed inside the bent panel to form a sandwich blank, and rolled to further reduce the tendency of the panel and preform to crack.

Generally, before rolling and compounding, the compound surface can be polished to remove an oxide layer so as to facilitate rolling and compounding.

In one embodiment, multi-pass rolling compounding is used. In a preferred embodiment, the reduction in the first pass is from 30 to 60%. The reduction after the second pass is about 15-30%. In one embodiment, the total reduction is greater than about 50%, preferably 50-95%, e.g., 60%, 70%, 80%. The suitable reduction ratio helps to obtain a composite panel having good interfacial strength without cracking. The method of the invention enables a higher holddown rate to be achieved, so that core layers of larger area can be produced with preforms of the same volume.

Step (4) foaming the composite board

The foaming treatment is important for obtaining the aluminum alloy sandwich panel with smooth surface, consistent thickness and good expansion rate and interface bonding rate.

In one embodiment, the foaming treatment of step (4) is a restricted location foaming. And (3) limiting the positions of the upper panel and the lower panel of the composite board by using a foaming mould, and filling the cavity with the expansion effect of liquid foam. The treatment is beneficial to obtaining the aluminum alloy sandwich panel with the lower panels parallel to each other, flat surface and high thickness consistency of all parts. Other types of foaming treatment such as heat preservation foaming can not achieve the effect, and the aluminum alloy sandwich board with smooth surface and consistent thickness can not be obtained. In addition, the foam core layer and the aluminum alloy panel can be metallurgically bonded by limiting the position for foaming treatment, so that higher interface bonding rate is obtained, strong interface bonding is formed, and the aluminum alloy sandwich panel can obtain excellent mechanical properties.

In one embodiment, the foaming temperature in the foaming treatment of step (4) is about 620 ℃ and 640 ℃, for example about 620, 630, 640 ℃. The foaming temperature is such that the core layer in the composite panel can be melted to effect foaming while the face sheet remains unmelted. Too high foaming temperature can cause the foaming agent to be decomposed violently, the viscosity of the aluminum liquid is reduced, and the problem of uneven pore structure is caused. The foaming temperature used by the invention is far lower than the melting point of the aluminum alloy panel (more than 645 ℃), so that the aluminum alloy panel can not be melted and deformed in the foaming process, and the foamed aluminum alloy sandwich panel with a smooth surface and high interface bonding strength can be obtained.

The time of foaming should be such that the foaming process can be completed. For example, it may be about 5-20min, such as about 11-18 min.

During the foaming process, the low-melting core layer is completely melted at a temperature lower than the decomposition temperature of the pre-treated foaming agent. The nucleation and growth of bubbles are completely carried out in liquid phase, and a core layer with high uniformity can be obtained.

In a preferred embodiment, the foaming mold may be preheated prior to foaming. The temperature of the preheating is, for example, about 620 ℃ and 640 ℃, such as about 620, 630, 640 ℃.

In one embodiment, step (4) is followed by a step of air cooling or air cooling the mold comprising the sandwich panel to room temperature.

In one embodiment, the expansion of the aluminium alloy core layer after the foaming treatment in step (4) is in the range of 200% to 600%, preferably 300% to 520%, for example 350%, 400%, 450%, 500%. The expansion ratio is the ratio of the height of the core layer after the foaming treatment to the height of the core layer before the foaming treatment.

The method of the present invention helps to achieve the desired expansion ratio. There is no possibility that the final desired expansion ratio of the product cannot be obtained due to a problem such as poor rolling.

Detailed description of the preferred embodiments

1. An aluminum alloy sandwich panel comprises a foam aluminum alloy core layer and an aluminum alloy panel,

wherein the foamed aluminum alloy core layer comprises

Based on the total weight of the foamed aluminum alloy core layer,

6-11% by weight of Si,

0-5% by weight of Cu,

0 to 3% by weight of Mn,

0-4% by weight of Zn, in the form of a powder,

0-0.8% by weight of Mg,

the balance of Al and inevitable impurities; the melting point of the aluminum alloy panel is above 645 ℃.

2. The sandwich panel of item 1, wherein the foamed aluminum alloy core layer comprises

Based on the total weight of the foamed aluminum alloy core layer,

7.0-10.7% by weight of Si, and/or

0-4.5 wt.% Cu, and/or

0-2% by weight of Mn, and/or

0-3% by weight of Zn, and/or

0-0.6 wt.% Mg.

3. The sandwich panel of item 1 or 2, wherein the foamed aluminum alloy core layer further comprises Ca in an amount of 0.25 to 3 wt.%, preferably 0.5 to 2.5 wt.%, based on the total weight of the foamed aluminum alloy core layer; and/or the foamed aluminium alloy core layer further comprises Sr in an amount of 40-400ppm, based on the total weight of the foamed aluminium alloy core layer.

4. The sandwich panel of any one of items 1 to 3, wherein the foamed aluminum alloy core layer has a melting point of about 615 ℃ or less, and/or

The melting point of the aluminum alloy panel is 645-.

5. The sandwich panel of any one of items 1 to 4, wherein the foamed aluminum alloy core layer is of a porous structure, and the foamed aluminum alloy core layer has an average equivalent pore size of 2 to 8mm, preferably 2.5 to 7.5 mm.

6. The sandwich panel of any one of items 1 to 5, wherein the area of the cells in the range of the average equivalent pore diameter ± 20% in the foamed aluminum alloy core layer accounts for more than 50%, preferably 60% to 85%, of the total area of the cells.

7. The sandwich panel of any one of items 1 to 6, wherein the foamed aluminum alloy core layer has a porosity of 70 to 90%, and/or

The density of the foamed aluminum alloy core layer is 0.27-0.81g/cm³。

8. The sandwich panel of one of items 1 to 7, wherein the aluminum alloy face sheet is a 3-series aluminum alloy or a 6-series aluminum alloy.

9. The sandwich panel according to any one of items 1 to 8, wherein the thickness of the aluminum alloy sandwich panel is 5 to 35 mm.

10. The sandwich panel of any one of items 1-9, wherein aluminum alloy face sheets are disposed on each side of the foamed aluminum alloy core layer, wherein the aluminum alloy face sheets are metallurgically joined to the aluminum alloy core layer.

11. The sandwich panel of one of items 1 to 10, wherein the aluminum alloy sandwich panel is obtained by a foaming process, wherein a temperature of the foaming is higher than a melting point of the foamed aluminum alloy core layer, and a temperature of the foaming is lower than a melting point of the aluminum alloy face sheet.

12. The sandwich panel of any one of items 1 to 11, wherein the preform for the foamed aluminum alloy core layer is prepared by a liquid phase process.

13. A method of making a sandwich panel of one of items 1-12 comprising the steps of:

(1) preparing an aluminum alloy melt of the foam aluminum alloy core layer,

(2) pouring the aluminum alloy melt into a mold for molding, and performing pressure maintaining solidification to obtain a prefabricated body of the foamed aluminum alloy core layer,

(3) rolling and compounding the prefabricated body and the initial aluminum alloy panel to obtain a composite plate,

(4) foaming the composite board;

wherein the foaming temperature is 620-640 ℃.

14. The method of item 13, wherein,

the step (1) comprises the following steps:

(1.1) adding an adhesion promoter to the initial aluminum alloy melt of the foamed aluminum alloy core layer,

(1.2) adding a foaming agent to the melt obtained in step (1.1).

15. The method of claim 14, wherein,

in step (1.1), the viscosity increasing agent is Ca; and/or

In step (1.1), further comprising adding an alterant, the alterant being an Al-Sr alloy, wherein the Sr content is 40-400ppm based on the total weight of the initial aluminum alloy melt.

16. The method of any one of items 13 to 15, wherein,

the initial aluminum alloy melt comprises

Based on the total weight of the initial aluminum alloy melt,

6-11% by weight of Si,

0-5% by weight of Cu,

0 to 3% by weight of Mn,

0-4% by weight of Zn, in the form of a powder,

0-0.8% by weight of Mg,

the balance of Al and inevitable impurities.

17. The method of any one of items 13-16, wherein,

in the step (1.2), the foaming agent is titanium hydride, and the titanium hydride is subjected to heat treatment at 490-540 ℃.

18. The method according to any one of items 13 to 17, wherein, in the step (2), the molding is extrusion molding, and/or

The pressure for maintaining the pressure is 3-80MPa, preferably 5-50 MPa.

19. The method according to any one of items 13 to 18, wherein the rolling in the step (3) is performed at a total rolling reduction of 50% or more, preferably 50 to 95%.

20. The method of one of items 13 to 19, wherein the foaming in step (4) is restricted-location foaming.

21. The method according to any one of items 13 to 20, wherein the expansion rate of the aluminum alloy core layer after the foaming treatment in step (4) is 200% to 600%, preferably 300% to 520%.

Advantageous effects

The sandwich plate prepared by the invention has the advantages of uniform hole size, smooth surface and firm interface combination. Has good mechanical property. The sandwich board has a core layer with higher expansion rate and uniform cell structure, so that the obtained sandwich board has higher specific strength. So that the product can meet the requirement of light weight.

According to the preparation method of the sandwich panel, the low-melting-point aluminum alloy with proper components is pretreated by the foaming agent and designed, foaming (position limiting foaming) is carried out at a constant temperature lower than the melting point of the panel, the low-melting-point core layer is melted and foamed, the panel is high in melting point and keeps solid state, the mold is gradually filled under the expansion action of the core layer, and the foamed aluminum alloy sandwich panel with a smooth surface is directly prepared.

Compared with the preparation methods such as a powder metallurgy method, a brazing method and the like, the method disclosed by the invention is low in raw material cost, high in pore structure uniformity, good in interface bonding strength, easy for large-scale production and high in production efficiency. The method comprises the steps of firstly forming a compact mechanical combination between a prefabricated core layer and a panel by hot rolling compounding, and then enabling the foam core layer and the panel to be metallurgically combined by foaming (position limiting foaming) at a constant temperature to form a strong combination interface. The method of preparing the preform in the method of the present invention may allow a preform production cycle time to be low, for example, less than 8 min. The rolling compounding enables the prefabricated body to generate plastic deformation during hot rolling, the size is further increased, and the production of the large sandwich panel can be efficiently carried out.

The method of the invention solves the defect that the foaming agent begins to rapidly decompose immediately after being added into the aluminum alloy melt, so that a large number of bubbles exist in the preform, and the preform is difficult to roll or foam again. The defects that the viscosity of aluminum liquid is high, the fluidity is poor, the casting molding is difficult, and a large amount of bubbles exist in the prefabricated body obtained after cooling due to the addition of the tackifier are avoided. The problems that solid-phase particles, bubbles and the like in the prefabricated body are easy to crack during rolling, can not be tightly combined with aluminum alloy panels on two sides, and can not prepare the foam aluminum alloy sandwich panel with large size, uniform pore structure and good interface bonding force are solved.

Examples

The present invention is described in further detail with reference to the following examples, which are not intended to limit the scope of the present invention.

The composition of the initial aluminum alloy melt from which the foamed aluminum alloy core layer was prepared is shown in table 1. The materials for making the aluminum alloy panels are shown in table 2.

TABLE 1

By weight%	Si	Cu	Mn	Zn	Al
						Example 1	9.2	2.2	1	1.5	Balance of
Example 2	7	4.5	0	1	Balance of
						Example 3	10.7	0	2	2	Balance of
Example 4	8.4	1.3	0.4	3	Balance of
						Example 5	8.8	3.6	1.3	0	Balance of
Example 6	7.6	4.1	1.6	0.8	Balance of
						Example 7	10.1	0.6	0.9	1.2	Balance of
Example 8	9.3	1.7	1.1	1.8	Balance of
						Comparative example 1	7	4.5	0	1	Balance of
Comparative example 2	7	4.5	0	1	Balance of
						Comparative example 3	7	4.5	0	1	Balance of

TABLE 2

By weight%	Aluminum alloy panel
		Example 1	6060 aluminium alloy
Example 2	6061 aluminium alloy
		Example 3	6082 aluminium alloy
Example 4	3004 aluminum alloy
		Example 5	6063 aluminium alloy
Example 6	3003 aluminum alloy
		Example 7	3005 aluminium alloy
Example 8	6951 aluminium alloy
		Comparative example 1	6061 aluminium alloy
Comparative example 2	6061 aluminium alloy
		Comparative example 3	6951 aluminium alloy composite boarda

^aThe composite layer is 10% AA4045

Example 1

1. Titanium hydride powder with the particle size of 200-300 meshes is placed in a crucible, placed in a crucible furnace, heated to 510 ℃, then kept for 70min, taken out and air-cooled to normal temperature to prepare the foaming agent.

2. The initial aluminum alloy components shown in table 1 for preparing the core layer were placed in a crucible in a heating furnace, and the temperature was raised to melt the aluminum alloy to form an aluminum alloy melt. Adding a strontium modifier into the initial aluminum alloy melt under the stirring condition of 800-1200rpm for modification treatment (the strontium modifier is aluminum-strontium alloy, wherein the strontium content is 10 wt% of the total weight of the aluminum-strontium alloy, and the dosage of the strontium modifier is 50ppm of the total weight of the aluminum alloy melt). Controlling the temperature of the aluminum alloy melt after modification at 700 ℃, and then adding tackifier metal calcium under the stirring condition of 800-1200rpm, wherein the addition amount is 1.5 wt% of the total weight of the aluminum alloy melt.

3. After the uniform stirring, the temperature of the aluminum alloy melt is controlled at 650 ℃ and the stirring speed of 1500-3000rpm, a foaming agent accounting for 1.3 percent of the total weight of the aluminum alloy melt is added, and the stirring is continued for 4min at the speed of 1500-3000rpm, so as to obtain the aluminum alloy melt for preparing the preform.

4. The mold was preheated to 450 ℃. An aluminum alloy melt for making a preform having a temperature of 650 ℃ was poured into the mold. And (3) forming the preform by adopting an extrusion casting mode, maintaining pressure and solidifying under the pressure of 50MPa, and cooling the die by using cooling water. And obtaining the plate-shaped prefabricated body after the aluminum liquid is solidified. The preform appearance is shown in fig. 2.

5. And polishing one side surface of the initial aluminum alloy panel to remove the oxide layer to form a polished surface. And polishing the surface of the prefabricated body to remove the oxide layer. And bending the polished initial aluminum alloy panel to a panel with a U-shaped vertical section, wherein the polished surface is positioned inside the panel. And placing the polished prefabricated body in the bent panel, and attaching the polished surface of the prefabricated body to the polished surface of the panel to form the sandwich blank.

6. Heating the sandwich blank to 400 ℃ for preheating for 30min, and then performing multi-pass rolling compounding. The reduction rate of the first pass is 30%, the reduction rate from the second pass is 15-30%, and the total reduction rate is 50%, so that the composite plate consisting of the outer hot-rolled aluminum alloy panel and the inner hot-rolled aluminum alloy core layer is manufactured.

7. The foaming mold was heated to 635 ℃ in a heating furnace for preheating. And then placing the composite board into a foaming mould, and controlling the temperature of the foaming mould to be 635 ℃ to carry out position-limited foaming for 18 min. In the foaming process, the aluminum alloy core layer is melted and foamed, and the aluminum alloy panel maintains the original shape. And filling the inner cavity of the foaming mold with the foamed composite board, taking out the foaming mold, and air-cooling or water-cooling to normal temperature to obtain the solidified sandwich board in the foaming mold.

The sandwich panel is composed of aluminum alloy face sheets and a foamed aluminum alloy core layer, such as shown in fig. 1. The aluminum alloy panel is metallurgically bonded with the foam aluminum alloy core layer, and the aluminum alloy panel covers the top surface and the bottom surface of the foam aluminum alloy core layer respectively.

The contents of Si, Cu, Mn, and Zn in the foamed aluminum alloy core layer of the sandwich panel of example 1 are shown in table 1, and further, 50ppm of Sr, 1.5 wt% of Ca, and 1.3 wt% of Ti introduced in the above processing steps 2 to 3, with the balance being Al. The porosity of the foamed aluminum alloy core layer is 84%, and the density is 0.44g/cm³. The thickness of the sandwich panel is 16 mm. The average equivalent pore diameter is 5.8mm, wherein the pore area of the pore diameter of 4.6mm to 7.0mm accounts for 78% of the pore area of the foamed aluminum alloy core layer. The core layer had an expansion rate of 500%, and the photograph of the cross section thereof is shown in FIG. 3.

Example 2

The method is the same as example 1, except that:

(1) heating the titanium hydride powder to 490 ℃, and keeping the temperature for 90 min;

(2) controlling the temperature of the aluminum alloy melt after modification to be 660 ℃. Adding the tackifier, stirring uniformly, and controlling the temperature of the aluminum alloy melt at 660 ℃. The strontium modifier is used in an amount of 100ppm based on the total weight of the aluminum alloy melt. The tackifier is added in an amount of 0.5 wt% based on the total weight of the aluminum alloy melt.

(3) Adding foaming agent accounting for 1.0 wt% of the total weight of the aluminum alloy melt and continuously stirring for 6min to obtain the aluminum alloy melt for preparing the preform.

(4) The mold was preheated to 550 ℃. An aluminium alloy melt for the preparation of a preform having a temperature of 660 ℃ is poured into the mould. Performing liquid casting and rolling, and maintaining the pressure until solidification and forming; the pressure during pressure maintaining is 10 MPa.

(5) The sandwich blank is heated to 410 ℃ for preheating, the rolling reduction rate of the first pass of rolling compounding is 35%, and the total rolling reduction rate is 50%.

(6) Preheating a foaming mould at 630 ℃; and controlling the temperature of the foaming mold to be 630 ℃ to carry out position-limited foaming for 15 min. In the foaming process, the aluminum alloy core layer is melted and foamed, and the aluminum alloy panel maintains the original shape.

The foamed aluminum alloy core layer of the sandwich panel of example 2 had a porosity of 75% and a density of 0.68g/cm³(ii) a The thickness of the sandwich plate is 10 mm. The average equivalent pore diameter of the core layer is 2.6mm, wherein the pore area with the pore diameter of 2.1mm to 3.1mm accounts for 65 percent of the total pore area of the foamed aluminum alloy core layer. The core layer had an expansion rate of 315%, and the photograph of the cross section thereof is shown in FIG. 4.

Example 3

The method is the same as example 1, except that:

(1) heating the titanium hydride powder to 540 ℃, and preserving the heat for 40 min;

(2) controlling the temperature of the aluminum alloy melt after modification at 750 ℃; adding the tackifier, stirring uniformly, and controlling the temperature of the aluminum alloy melt at 620 ℃. The strontium modifier is used in an amount of 150ppm based on the total weight of the aluminum alloy melt. The tackifier is added in an amount of 2.5 wt% based on the total weight of the aluminum alloy melt.

(3) Adding foaming agent accounting for 1.4 wt% of the total weight of the aluminum alloy melt and continuously stirring for 3min to obtain the aluminum alloy melt for preparing the preform.

(4) The mold was preheated to 480 ℃. An aluminium alloy melt for the preparation of a preform having a temperature of 620 ℃ is poured into the mould. Performing liquid die forging, and maintaining the pressure until solidification and forming; the pressure during pressure maintaining is 40 MPa.

(5) Heating the sandwich blank to 420 ℃ for preheating, and rolling and compounding the sandwich blank at a reduction rate of 30% in the first pass and at a total reduction rate of 50%.

(6) Preheating a foaming mould at 620 ℃; and controlling the temperature of the foaming mold to be 620 ℃ to carry out position-limited foaming for 18 min. In the foaming process, the aluminum alloy core layer is melted and foamed, and the aluminum alloy panel maintains the original shape.

The foamed aluminum alloy core layer of the sandwich panel of example 3 had a porosity of 85% and a density of 0.4g/cm³(ii) a The thickness of the aluminum alloy sandwich plate is 30 mm. The core layer has an average equivalent pore diameter of 6.9mm, wherein the pore area of 5.5mm to 8.3mm pore diameter accounts for 85% of the total pore area of the foamed aluminum alloy core layer. The expansion of the core layer was 520%.

Example 4

The method is the same as example 1, except that:

(1) heating the titanium hydride powder to 510 ℃ and preserving the heat for 60 min;

(2) controlling the temperature of the aluminum alloy melt after modification at 680 ℃; adding the tackifier, stirring uniformly, and controlling the temperature of the aluminum alloy melt at 645 ℃. The strontium modifier is used in an amount of 200ppm based on the total weight of the aluminum alloy melt. The tackifier accounts for 2.0 weight percent of the total weight of the aluminum alloy melt.

(3) The foaming agent was added and stirring was continued for 210 seconds to obtain an aluminum alloy melt for producing a preform.

(4) Preheating the die to 490 ℃; pouring an aluminum alloy melt for preparing a preform at a temperature of 645 ℃ into a mold; the pressure during pressure maintaining is 20 MPa.

(5) Heating the sandwich blank to 430 ℃ for preheating, and rolling and compounding the sandwich blank with the first pass of reduction rate of 40% and the total reduction rate of 75%.

(6) Preheating a foaming mould at 640 ℃; and controlling the temperature of the foaming mold to be 640 ℃ to carry out position-limited foaming for 17 min. In the foaming process, the aluminum alloy core layer is melted and foamed, and the aluminum alloy panel maintains the original shape.

The foamed aluminum alloy core layer of the sandwich panel of example 4 had a porosity of 81% and a density of 0.52g/cm³. The thickness of the aluminum alloy sandwich plate is 25 mm. The average pore diameter of the core layer is 4.4mm, wherein the pore area of the pore diameter of 3.5mm to 5.3mm accounts for the foamed aluminum alloy75% of the total area of the gold core pores. The expansion of the core layer was 450%.

Example 5

The method is the same as example 1, except that:

(1) heating the titanium hydride powder to 530 ℃ and preserving the heat for 50 min;

(2) controlling the temperature of the aluminum alloy melt after modification at 710 ℃; adding the tackifier, stirring uniformly, and controlling the temperature of the aluminum alloy melt at 630 ℃. The strontium modifier is used in an amount of 250ppm based on the total weight of the aluminum alloy melt. The tackifier is 1.6 wt% of the total weight of the aluminum alloy melt.

(3) Adding foaming agent and continuously stirring for 3min to obtain the aluminum alloy melt for preparing the preform.

(4) Preheating a mould to 510 ℃; an aluminium alloy melt for making a preform having a temperature of 630 ℃ was poured into the mould. Performing extrusion casting, and maintaining the pressure until solidification molding; the pressure during pressure maintaining is 30 MPa.

(5) The sandwich blank is heated to 440 ℃ for preheating, and the rolling reduction rate of the first pass of rolling compounding is 35 percent, and the total rolling reduction rate is 60 percent.

(6) Preheating a foaming mould at 625 ℃; and controlling the temperature of the foaming mold to be 625 ℃ to carry out position-limited foaming for 14 min. In the foaming process, the aluminum alloy core layer is melted and foamed, and the aluminum alloy panel maintains the original shape.

The foamed aluminum alloy core layer of the sandwich panel of example 5 had a porosity of 83%, a density of 0.45g/cm³(ii) a The thickness of the aluminum alloy sandwich plate is 22 mm. The core layer has an average equivalent pore diameter of 6.0mm, wherein the pore area of 4.8 to 7.2mm pore diameter accounts for 80% of the total pore area of the foamed aluminum alloy core layer. The expansion of the core layer was 500%.

Example 6

The method is the same as example 1, except that:

(1) heating the titanium hydride powder to 490 ℃, and keeping the temperature for 100 min;

(2) controlling the temperature of the aluminum alloy melt after modification at 730 ℃. Adding the tackifier, stirring uniformly, and controlling the temperature of the aluminum alloy melt at 660 ℃. The strontium modifier is used in an amount of 300ppm based on the total weight of the aluminum alloy melt.

(3) Adding foaming agent and continuously stirring for 6min to obtain the aluminum alloy melt for preparing the preform. The tackifier is 1.5 wt% of the total weight of the aluminum alloy melt.

(4) Preheating the die to 530 ℃; an aluminium alloy melt for the preparation of a preform having a temperature of 660 ℃ is poured into the mould. Pressure is maintained in a liquid die forging mode until solidification and forming are carried out; the pressure during pressure maintaining is 15 MPa.

(5) The sandwich blank is heated to 450 ℃ for preheating, the rolling reduction rate of the first pass of rolling compounding is 40%, and the total rolling reduction rate is 67%.

(6) Preheating a foaming mould at 640 ℃; and controlling the temperature of the foaming mold to be 640 ℃ to carry out position-limited foaming for 11 min. In the foaming process, the aluminum alloy core layer is melted and foamed, and the aluminum alloy panel maintains the original shape.

The foamed aluminum alloy core layer of the sandwich panel of example 6 had a porosity of 77% and a density of 0.63g/cm³. The thickness of the aluminum alloy sandwich plate is 8 mm. The core layer has an average equivalent pore diameter of 3.0mm, wherein the pore area of 2.4 to 3.6mm pore diameter accounts for 60% of the total pore area of the foamed aluminum alloy core layer. The expansion of the core layer was 350%.

Example 7

The method is the same as example 1, except that:

(1) heating the titanium hydride powder to 500 ℃, and keeping the temperature for 80 min;

(2) controlling the temperature of the aluminum alloy melt after modification at 750 ℃; adding the tackifier, stirring uniformly, and controlling the temperature of the aluminum alloy melt at 650 ℃. The strontium modifier is used in an amount of 300ppm based on the total weight of the aluminum alloy melt. The tackifier is 1.0 wt% of the total weight of the aluminum alloy melt.

(3) The foaming agent was added and stirring was continued for 330s to obtain an aluminum alloy melt for preparing a preform.

(4) The mold was preheated to 550 ℃. Pouring an aluminum alloy melt for preparing a preform at the temperature of 650 ℃ into a mold; the pressure during pressure maintaining is 5 MPa.

(5) The sandwich blank is heated to 445 ℃ for preheating, the rolling reduction rate of the first pass of rolling compounding is 45 percent, and the total rolling reduction rate is 80 percent.

(6) Preheating a foaming mould at 640 ℃; and controlling the temperature of the foaming mold to be 640 ℃ to carry out position-limited foaming for 13 min. In the foaming process, the aluminum alloy core layer is melted and foamed, and the aluminum alloy panel maintains the original shape.

The foamed aluminum alloy core layer of the sandwich panel of example 7 had a porosity of 78% and a density of 0.60g/cm³(ii) a The thickness of the aluminum alloy sandwich plate is 17 mm. The average equivalent pore diameter of the core layer is 3.6mm, wherein the pore area of the pore diameter of 2.9mm to 4.3mm accounts for 70 percent of the total pore area of the foamed aluminum alloy core layer. The expansion of the core layer was 375%.

Example 8

The method is the same as example 1, except that:

(1) heating the titanium hydride powder to 520 ℃, and keeping the temperature for 60 min;

(2) controlling the temperature of the aluminum alloy melt after modification at 750 ℃; adding tackifier and stirring uniformly, and controlling the temperature of the aluminum alloy melt at 640 ℃. The strontium modifier is used in an amount of 300ppm based on the total weight of the aluminum alloy melt. The tackifier is metallic calcium, wherein the metallic calcium accounts for 1.2 wt% of the total weight of the aluminum alloy melt.

(3) Adding foaming agent and continuously stirring for 5min to obtain the aluminum alloy melt for preparing the preform.

(4) Preheating a mould to 550 ℃; pouring an aluminum alloy melt for preparing a preform at the temperature of 640 ℃ into a mold; the pressure during pressure maintaining is 25 MPa.

(5) Heating the sandwich blank to 435 ℃ for preheating, and rolling and compounding the sandwich blank to 45% of reduction rate of the first pass and 67% of total reduction rate;

(6) preheating a foaming mould at 630 ℃; and controlling the temperature of the foaming mold to be 630 ℃ to carry out position-limited foaming for 12 min. In the foaming process, the aluminum alloy core layer is melted and foamed, and the aluminum alloy panel maintains the original shape.

The foamed aluminum alloy core layer of the sandwich panel of example 8 had a porosity of 78% and a density of 0.60g/cm³(ii) a The thickness of the aluminum alloy sandwich plate is 18 mm. The core layer has an average equivalent pore diameter of 3.8mm, wherein the pore area of 3.1mm to 4.6mm pore diameter accounts for 75% of the total pore area of the foamed aluminum alloy core layer. The expansion of the core layer was 375%.

Comparative example 1

The method is the same as example 1, except that:

(1) heating the titanium hydride powder to 490 ℃, and keeping the temperature for 90 min;

(2) controlling the temperature of the aluminum alloy melt after modification to be 660 ℃. Adding the tackifier, stirring uniformly, and controlling the temperature of the aluminum alloy melt at 660 ℃. The strontium modifier is used in an amount of 100ppm based on the total weight of the aluminum alloy melt. The tackifier is added in an amount of 1.0 wt% based on the total weight of the aluminum alloy melt.

(3) Adding foaming agent accounting for 1.2 wt% of the total weight of the aluminum alloy melt and continuously stirring for 6min to obtain the aluminum alloy melt for preparing the preform.

(4) The mold was preheated to 550 ℃. An aluminium alloy melt for the preparation of a preform having a temperature of 660 ℃ is poured into the mould. Pressure solidification means is not adopted. And (4) finding that the surface of the obtained prefabricated body is extremely uneven after the step (4), and the prefabricated body cannot be directly used for rolling and compounding.

(5) And leveling the surface of the prefabricated part by using a milling machine to prepare the composite board. A large number of small bubble defects are found in the convex part of the preform during the rolling process of the preform. The sandwich blank is heated to 410 ℃ for preheating, the rolling reduction rate of the first pass of rolling and compounding is 30%, and the crack with the length of 40mm appears at the central part of the prefabricated body of the composite plate, so that the composite plate can not be further rolled.

Comparative example 2

The method is the same as example 1, except that:

(1) heating the titanium hydride powder to 490 ℃, and keeping the temperature for 90 min;

(2) controlling the temperature of the aluminum alloy melt after modification to be 660 ℃. Adding the tackifier, stirring uniformly, and controlling the temperature of the aluminum alloy melt at 660 ℃. The strontium modifier is used in an amount of 100ppm based on the total weight of the aluminum alloy melt. The tackifier is added in an amount of 0.5 wt% based on the total weight of the aluminum alloy melt.

(3) Adding foaming agent accounting for 1.2 wt% of the total weight of the aluminum alloy melt and continuously stirring for 6min to obtain the aluminum alloy melt for preparing the preform.

(4) The mold was preheated to 550 ℃. An aluminium alloy melt for the preparation of a preform having a temperature of 660 ℃ is poured into the mould. Performing liquid casting and rolling, and maintaining the pressure until solidification and forming; the pressure during pressure maintaining is 10 MPa.

(5) The sandwich blank is heated to 410 ℃ for preheating, the rolling reduction rate of the first pass of rolling compounding is 35%, and the total rolling reduction rate is 50%.

(6) And (4) placing the prefabricated body on the surface of the preheated steel bottom plate without adopting limiting foaming.

Preheating a steel base plate at 680 ℃; and controlling the temperature of the foaming furnace to 680 ℃ for heat preservation foaming for 10 min. In the foaming process, the aluminum alloy core layer is melted and foamed, the aluminum alloy panel is also melted and deformed, the upper surface of the prepared sandwich board is convex, and the two sides of the sandwich board collapse. And the panels are fused with the core material, so that the upper and lower panels cannot be maintained parallel and have the same thickness.

Comparative example 3

Comparative example 3 an aluminum alloy sandwich panel was prepared by welding. Specifically, a foamed aluminum alloy core material was prepared by a conventional foaming method according to the composition in table 1, and the obtained foamed aluminum alloy core material was cut. Subsequently, aluminum alloy composite panels are provided and a flux aid (Nocolock) is applied to the surfaces of the panels to be welded^TM) And brazing the foamed aluminum alloy core material and the aluminum alloy composite panel at the temperature of 595-610 ℃ under the protection of nitrogen so as to combine the foamed aluminum alloy core material and the aluminum alloy composite panel and form the aluminum alloy sandwich panel. And cooling the sample after the brazing is finished, thus obtaining the aluminum alloy sandwich panel of the comparative example 3.

Examples of the experiments

Metallographic microscope picture of aluminum alloy sandwich plate

The instrument comprises the following steps: nikon LV150N metallographic microscope

Detection conditions are as follows: the contact interface between the core alloy and the aluminum alloy face sheet in the aluminum alloy sandwich panel was observed under a 100-fold magnification using a nikon LV150N metallographic microscope.

The aluminum alloy sandwich panels of example 1 and comparative example 3 were taken, and the contact interface between the core alloy and the aluminum alloy panel was observed using a metallographic microscope, respectively, to obtain metallographic microscope pictures shown in fig. 5 (the aluminum alloy sandwich panel of example 1) and fig. 6 (the aluminum alloy sandwich panel of comparative example 3). FIG. 5 shows that in the foamed aluminum alloy sandwich panel of the present invention, the aluminum alloy panel 2 is completely bonded to the foam core layer 1, and the interface bonding rate is 99% or more; in the aluminum alloy sandwich panel of the comparative example 3, the aluminum alloy panel is connected with the brazing layer, and the bonding rate of the foam core layer and the brazing layer is lower than 20%.

In summary, the core layers of the sandwich panels of examples 1-8 had the desired porosity, density and thickness. The core layer has uniform pores, and the pore area within the range of the average equivalent pore diameter +/-20 percent accounts for more than 60 percent of the total pore area. The expansion rate of the core layer is more than 300%. The interface bonding rate of the foamed aluminum alloy core layer and the aluminum alloy panel is more than 95%.

The sample of comparative example 1 was not solidified using pressure holding, a large number of small bubbles were present in the preform, and further rolling was difficult.

Comparative example 2 no position-restricted foaming was used and insulation foaming was performed using a foaming temperature of 680 c, and a sample in which a panel was fused with a core material and an upper surface of a sandwich panel was protruded and both sides were collapsed was obtained, and a finished product having good expansion rate and workability could not be obtained.

Comparative example 3 no position limiting foaming is adopted, the aluminum alloy core layer is connected with the aluminum alloy panel in a brazing mode, the interface bonding rate of the core material and the panel is less than 20%, good mechanical properties cannot be obtained, and further processing and application of the aluminum alloy sandwich panel are not facilitated.

It can be seen that in the method for preparing the aluminum alloy sandwich panel of the invention, the pressure-maintaining solidification and the limited position foaming are used for obtaining the aluminum alloy sandwich panel with smooth surface, consistent thickness and good pore structure and expansion rate. The pressure-maintaining solidification is beneficial to reducing small bubbles in the prefabricated body, is beneficial to subsequent rolling, and obtains the aluminum alloy sandwich plate with good porosity, density and thickness. Limiting the location foaming helps to obtain an aluminum alloy sandwich panel with good expansion ratio.

While the invention has been illustrated and described with reference to exemplary embodiments, the invention is not intended to be limited to the details shown. Since various modifications and substitutions may be made by those skilled in the art without departing from the spirit of the invention, it is intended that all such modifications and equivalents will fall within the spirit and scope of the invention as defined by the appended claims. It will be apparent to those skilled in the art that modifications and variations can be made in the embodiments without departing from the spirit of the invention. All such modifications and variations are intended to be included herein within the scope of the appended claims.