JPS591651A - Manufacture of porous metal - Google Patents

Abstract

PURPOSE:To easily manufacture a porous metal having a homogeneous internal structure, by filling water-soluble crystals having a regulated grain size into a heat resistant vessel, charging a molten metal having a lower m.p. than the crystals into the vessel, applying pressure to infiltrate the metal into the gaps among the crystals, solidifying the metal, and adding water to dissolve and remove the crystals. CONSTITUTION:NaCl crystals 2 regulated to a desired grain size are evenly filled into a heat resistant vessel 1, and a molten Al alloy 3 having a lower m.p. than the crystals 2 is charged into the vessel 1. Pressure is applied to the inside of the vessel 1 by means of a piston 4 or the like to infiltrate well the alloy 3 into the gaps among the crystals 2. The alloy 3 is then solidified by cooling. The resulting solid mixture 7 consisting of the crystals 2 and the solidified Al alloy 3' is taken out of the vessel 1, and by adding water, the crystals 2 are dissolved and allowed to flow out of the mixture 7 to form spaces 9. Thus, a porous Al alloy 10 having many internal spaces 9 as continuous cells is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing metal foam used for rigid energy generators, heat exchangers, soundproof walls, and the like.

Conventionally, when producing a foamed metal having a large number of open cell spaces inside, a special foaming agent is used to induce a foaming phenomenon in the molten metal, and the molten metal is heated in this state. A method of cooling and solidifying is generally adopted. However, in such a method, there is a problem in that it is difficult to uniformly disperse air bubbles in the molten metal, making it difficult to obtain a foamed metal having a homogeneous internal structure.

In addition, the above-mentioned foaming agents are expensive and many of them are highly toxic, so they are disadvantageous in that they tend to cause pollution.

The present invention was made with attention to such circumstances, and
A heat-resistant container is filled with a large number of water-soluble crystals of adjusted particle size, and a molten metal having a melting point lower than that of the crystals is poured into the container, and a pressure is applied to the container. After sufficiently infiltrating the molten metal into the space formed between the crystal bodies, the temperature of the molten metal is lowered and solidified to produce a solid mixture of the crystal bodies and the metal, and hydration is added to the mixed solid. to elute the crystals.
Therefore, the present invention provides a method for manufacturing a metal foam that can easily manufacture a metal foam having a homogeneous internal structure.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

First, place 2 crystals of sodium chloride whose particle size has been adjusted to the desired value in a heat-resistant container of 1 yen! . . equally I′C, fill (first
(see figure). Next, a molten aluminum alloy 8, for example a molten metal at a temperature lower than the melting point (800°C) of the crystal body 2, is poured into the container 1 (see FIG. 2). At this time, the temperature inside the heat-resistant container 1 is the same as that of the aluminum alloy 8.
Keep it above the melting point of . Next, the sodium chloride crystals 2... and the molten aluminum alloy 8I in this container 1 are placed in the piston 4 and pressure is applied, and the molten aluminum alloy 3 is placed between the sodium chloride crystals 2... It is made to fully penetrate into the gap 6 that has been formed. (See Figure 8) After that, this molten aluminum alloy 8
Cool and solidify. Accordingly, the sodium chloride crystal 2... and the solidified aluminum alloy 8/
A solid 7 is produced which is a mixture of the following. At this time, the sodium chloride crystals 2 are filled approximately evenly within the solid 7, so that the solid 7 is approximately homogeneous as a whole. Thereafter, when this solid 7 is taken out from the container 1 and water is added to the solid 7I (the water 8 to be added should be close to 100°C), the sodium chloride crystals 2 are dissolved by this addition of water, and the solid 7 is It flows out from there, and the trace of that flow becomes space 9... (See FIG. 4) In this manner, a metal foam 10 made of aluminum alloy 3 and having a large number of open cell spaces 9 inside is manufactured.

Note that the present invention is of course not limited to the above embodiments, and the crystalline material is not limited to sodium chloride, but any water-soluble material having a melting point higher than that of the molten metal may be used. Further, the material of the metal foam is of course not limited to aluminum alloy, but may be an alloy of lead, for example, or may be a single metal instead of an alloy. In addition, the pressure applied inside the container may be applied appropriately as necessary, and this pressure does not have to be applied by the piston I, but by, for example, increasing the air pressure inside the container. Good too.

As explained above, the present invention uses a solid crystal instead of bubbles generated by a blowing agent or the like to form open cell-like spaces in the metal structure. By simply adjusting the particle size of the body and filling it into an insulated container, it is possible to obtain a highly homogeneous internal structure without the uncertainty that occurs when dispersing foam. It is possible to reliably produce metal foam. Moreover, since water-soluble crystals are used as the crystals, the crystals can be removed from the inside of the metal by a simple operation of solidifying the metal and then adding water, and the crystals can be replaced with foam. There is no inconvenience that the work is complicated due to the use of this solid crystal.

In addition, if sodium chloride crystals are used as the crystals as in the above embodiment, not only will it be extremely inexpensive, but
The waste water produced by dissolving the crystals becomes a harmless substance similar to seawater, so it has the advantage that it does not cause any pollution even if it is disposed of as is.

[Brief explanation of drawings]

1 to 4 are process explanatory diagrams showing one embodiment of the present invention,
FIG. 5 is a sectional view showing the foamed metal in the same example. 1... Heat insulating container 2... Crystal body 8... Molten metal (aluminum alloy) 8I...
Solidified metal (aluminum alloy) 6...Gap 7
...Solid 8...Water 9...Space 10...
Foam metal agent Patent attorney Hiroshi Akazawa

Claims (1)

[Claims] A heat-resistant container is filled with a large number of water-soluble crystals of adjusted particle size, and a molten metal having a lower melting point than the crystals is poured into the container. The molten metal is allowed to fully penetrate into the gap formed between the crystals, and then the temperature of the molten metal is lowered and solidified to produce a solid mixture of the crystals and the metal. 1. A method for producing a metal foam, characterized in that the metal foam is produced by adding water and eluting crystals.