KR20080091920A - Foamed metal and its manufacturing method - Google Patents

Abstract

Foamed metals and methods for their preparation are provided. The foamed metal includes a porous metal layer and a heating bar dispersed in the porous metal layer. The heating bar may have a heat pipe structure or a metal wire structure filled with the inside. In the case of a heat pipe structure, the heat pipe may be an open type or a closed heat pipe structure filled with a refrigerant. In the manufacturing method of the foamed metal, a metal material, a blowing agent, and a heating bar are mixed, and heat treatment is applied to the mixed material to form a porous metal structure in which the heating bar is dispersed.

Description

Foamed metal and its manufacturing method {METALLIC FORM AND METHOD OF FABRICATING THE SAME}

1 is a view showing a foamed metal according to a preferred embodiment of the present invention.

2a to 2c show a heating bar dispersed in a foamed metal according to a preferred embodiment of the present invention.

3 and 4 are each a flow chart showing a method for forming a foam metal according to a preferred embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: foamed metal 102: porous metal layer

104: heating bar 204: closed heat pipe

304: open heat pipe 404: metal wire

The present invention relates to a foamed metal having a porous structure, and more particularly to a foamed metal in which heat can be uniformly transferred to the porous metal layer during heat treatment.

Foamed metal contains pores in the metal and is commonly used as a porous metal obtained in a molten state. Foamed metals are used in lightweight structures, sound absorbers, vibration dampers and heat exchangers because of their low density, incombustibility, sound absorption and excellent mechanical properties.

As a typical manufacturing method of the foamed metal, hydrogen gas generated by decomposition of the gas release particles added to the molten metal forms pores to produce the foamed metal. According to this method, the structure of the foamed metal is greatly influenced by the surface tension, viscosity and temperature of the melt. Therefore, there is a difficulty in producing a foamed metal having a fine cell size while controlling a homogeneous porous structure from the molten metal.

Recently, a powder manufacturing method capable of directly forming a foamed metal having a complicated shape as well as having a relatively uniform foam structure has been introduced. In the powder manufacturing method, the metal powder and the blowing agent are mixed well, and the powder is pressed to form a solid semi-finished product. When the temperature of the solid foam metal is raised to near the melting point, the foaming agent reacts and foaming starts, creating numerous pores inside the metal. Even when the powder manufacturing method is used, there is a problem that the difference in temperature between the inside and the outside of the foamed metal is present when the foamed metal is manufactured in a large capacity, thereby increasing the formation of crystals and the dispersion of density.

The technical problem to be achieved by the present invention is to provide a foamed metal and a method of manufacturing the same that can be uniformly heat transfer in the manufacturing process.

Another object of the present invention is to provide a foamed metal having a uniform size and density of cells of the porous metal layer and a method of manufacturing the same.

In order to achieve the above technical problem, the present invention provides a foamed metal in which a heat transfer means is dispersed. The foamed metal includes a porous metal layer and a heating bar dispersed in the porous metal layer. The heating bar may have a heat pipe structure or a metal wire structure filled with the inside. In the case of a heat pipe structure, the heat pipe may be an open type or a closed heat pipe structure filled with a refrigerant.

In order to achieve the above technical problem, the present invention provides a method for producing a foamed metal in which a heat transfer means is dispersed. The method is characterized by mixing a metal material, a blowing agent and a heating bar, and applying heat treatment to the mixed material to form a porous metal structure in which the heating bar is dispersed.

In one embodiment of the present invention, the foamed metal may be formed by applying a melting method. Specifically, the method includes melting the metal material and dispersing a heating bar in the molten metal material. A blowing agent is added to the molten metal material and stirred. By the reaction of the blowing agent, bubbles are formed in the metal material and solidified. The heating bar may have a melting temperature higher than the melting temperature of the metal material, and may be evenly dispersed in the porous metal layer which is dispersed and solidified in the molten metal material.

In another embodiment of the present invention, the foamed metal may be formed by applying a powder manufacturing method. Specifically, the method includes mixing the powder of the metal material, the blowing agent powder and the heating bar, and compression-sintering the mixed materials to form a semifinished product. Heat treatment is applied to the semi-finished product to react the blowing agent to form a porous metal structure. At this time, the heat treatment may be performed at a temperature near the melting point or above the melting point of the metal material to form bubbles in the metal material by the reaction of the blowing agent and to cool to form a porous metal layer.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the scope of the invention to those skilled in the art will fully convey. Like numbers refer to like elements throughout.

<Example>

1 is a view showing a foamed metal according to a preferred embodiment of the present invention.

Referring to FIG. 1, a foamed metal 100 according to a preferred embodiment of the present invention includes a porous metal layer 102 and a heating bar 104 evenly distributed within the metal layer. The metal layer 102 may have an open or closed porous structure.

The metal layer material may be various metals such as aluminum, titanium, silver, nickel, and copper. The heating bar 104 is evenly dispersed in the metal layer 102 to help uniform heat transfer during heat treatment in the process of foaming metal, and to function as a reinforcing agent to increase the rigidity and improve the strength of the metal layer 102. It may be.

The heating bar 104 may be a metal having a length of several mm, and preferably has a higher melting point and higher thermal conductivity than the porous metal layer 102.

The heating bar 104 may have a variety of structures to reduce the temperature difference between the inside and the outside when forming the foam metal and to act as a reinforcing agent in the foam metal.

2A to 2C are views for explaining the structure of the heating bars dispersed in the porous metal layer, respectively.

Referring to FIG. 2A, the heating bar 104 according to the present invention may have a closed heat pipe 204 structure. The heat pipe 204 may have an empty structure, and a refrigerant may be filled in the empty space. The refrigerant filled in the heat pipe 204 may be selected from materials having a coefficient of thermal expansion such that the heat pipe 204 is not destroyed at the melting temperature of the foamed metal material.

Referring to FIG. 2B, the heating bar 104 may have an open heat pipe 304 structure as a structure different from that of FIG. 2A. The heat pipe 304 is a pipe structure that is open at both sides, the foam metal is also filled in the heat pipe 304 in the foam metal can be more firmly coupled to the porous metal layer 102 and the heat pipe 304. And function as an enhancer can also be improved.

Referring to FIG. 2C, the heating bar 104 dispersed in the porous metal layer 102 may be a metal wire 404 filled with a length of several mm. The metal wire has a higher melting point than the porous metal layer 102 and may exist while functioning as a heat transfer medium even when the metal material is melted. For example, when the porous metal layer 102 is aluminum, since the melting point of aluminum is 660 degrees, a copper wire having a melting point of 1083 degrees may be used as a heating bar.

As described above, since the heating metal is uniformly dispersed in the porous metal layer in the porous metal layer, the heat transfer is uniform in the forming process of the foaming metal, and thus may have a structure in which the size and density of the cell are less scattered. In addition, the heating bar dispersed in the foamed metal may serve as a reinforcing agent to increase the rigidity and improve the strength of the foamed metal.

Hereinafter, a method for forming a foam metal according to a preferred embodiment of the present invention. The foamed metal may be formed by melting a metal material or may be formed by compression plastic working of a metal powder.

<First Embodiment>

3 is a flowchart illustrating a method for forming a foamed metal according to a first embodiment of the present invention.

Referring to FIG. 3, first, the expanded metal material is heated above the melting point to be melted in a melting furnace (S1 step). The melting furnace may be a conventional induction heating furnace or an electric furnace and the like, the melting temperature may be adjusted according to the metal to be dissolved.

A thickener may be added while stirring the molten melt in the melting furnace with a stirrer. The thickener is intended to increase the viscosity of the melt so that bubbles can be trapped in the melt. Calcium is suitable as the thickener, and it is suitable to add 1 to 2% by weight of the molten metal.

The heating bar is dispersed in the molten metal to which the thickener is added (step S2). The heating bar is dispersed in the molten metal, and the heating bar is dispersed evenly mixed.

Subsequently, a blowing agent is added while stirring a molten metal using a stirrer (step S3). In general, as the blowing agent, a metal hydrogen compound such as TiH ₂ , ZrH ₂ , MgH may be used, and a gas such as Ar or nitrogen may be used.

Bubbles are generated in the molten metal by hydrogen gas generated by the metal hydrogen compound or injected argon or nitrogen gas, and the reacted foamed metal swells from the molten metal. The foamed metal can be prepared (step S4).

Second Embodiment

4 is a flowchart illustrating a method for forming a foamed metal according to a second embodiment of the present invention.

Referring to Figure 4, the foamed metal according to the present invention can also be produced by a powder manufacturing method. First, the metal powder, the blowing agent and the heating bar are mixed well (step S11).

Subsequently, the mixed powder is pressed to form a semi-finished full product (step S12). The semifinished product molding can be molded into semi-finished products of various shapes by putting the mixed powder in a mold of a desired shape and pressing. In addition, the solidified semifinished foam metal may be further processed into the desired shape.

When the solidified and molded semi-finished product is heated to a temperature above the melting point or the melting point, the blowing agent reacts to start foaming, and numerous pores are formed inside the metal to form the foamed metal (step S13).

According to the invention, the heating bar is evenly distributed in the solidified semifinished product. Therefore, when heating from the outside of the semi-finished product is not uniformly heat transfer to the inside of the semi-finished product can be suppressed that the scattering of the size and density of the cell occurs. In addition, even when the semi-finished product is heated above the melting point, since the heating bar is maintained without melting, the heating bar is dispersed in the foamed metal as it is, so that it may function as a reinforcing agent in the finished foamed metal.

Since the foaming metal according to the present invention is uniformly dispersed heating bar in the porous metal layer, it is possible to have a structure in which the heat transfer is uniform in the forming process of the foamed metal and the scattering of the size and density of the cell is small. In addition, the heating bar dispersed in the foamed metal may serve as a reinforcing agent to increase the rigidity and improve the strength of the foamed metal.

Claims (7)

A foamed metal comprising a porous metal layer and a heating bar dispersed in the porous metal layer. The method of claim 1, The heating bar is a foamed metal, characterized in that the heat pipe structure. The method of claim 2, The heating bar is a foamed metal, characterized in that the closed heat pipe structure filled with a refrigerant. The method of claim 1, The heating bar is a foamed metal, characterized in that the metal wire filled inside. A method of manufacturing a foamed metal, comprising mixing a metal material, a blowing agent, and a heating bar, and applying heat treatment to the mixed material to form a porous metal structure in which the heating bar is dispersed. The method of claim 5, wherein Melting the metal material, Disperse a heating bar in the molten metal material, A blowing agent is added to the molten metal material and stirred, The foaming metal manufacturing method characterized by forming a bubble in a metal material and solidifying by reaction of the said blowing agent. The method of claim 5, wherein Mixing the powder of the metal material, the blowing agent powder and the heating bar, Compression sintering the mixed materials to form a semifinished product, Method for producing a foamed metal, characterized in that the heat treatment is applied to the semi-finished product to form a porous metal structure by reacting the blowing agent.

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