JP2657575B2 - Manufacturing method of foam metal - Google Patents

Description

The present invention relates to a method for producing a foamed metal.

[Conventional technology and its problems]

As a conventional method for producing a foamed metal, for example, a method using casting, electric plating, or powder sintering is known. However, each of these methods involves a complicated manufacturing process such as molding using a foamed resin such as urethane foam, and burning the resin after molding or erasing the resin using a solvent. Further, depending on the production method, the produced porous foamed metal is inhomogeneous, weighs insignificantly inferior in strength, and has a low porosity.

[Means for solving the problem]

The present invention has been made in view of such a conventional technical problem, and the structure of the invention according to claim (1) has a structure in which the temperature of the metal powder is lower than the melting temperature of the metal powder. To form a mixture with an intervening substance having a boiling point of, and the mixture is hermetically housed in a container having a melting temperature equal to or higher than the melting temperature of the metal powder, and in a microgravity state, the temperature of the container is increased. This is a method for producing a foamed metal in which the metal powder and the container are dissolved, the intervening substance is vaporized, and then the molten metal is cooled and solidified.

Further, according to the structure of the invention described in claim (2), an intervening substance having a boiling point equal to or higher than the melting temperature of the metal powder is interposed between the metal powders to form a mixture, and the mixture is formed. The mixture is airtightly housed in a container that is destroyed by the vaporization of the substance, and in a microgravity state, the temperature of the mixture is raised to dissolve the metal particles and vaporize the intervening substance, and then the molten metal is cooled and solidified. This is a method for producing a foam metal to be formed.

[Action]

According to the invention described in claim (1), the airtight container containing the mixture of the metal powder and the intervening substance is a heating device for a device capable of imparting a microgravity state, such as a falling capsule or an aircraft. Housed within.

Then, a microgravity state is given to heat and melt the metal powder and the container. Since the pressure drop occurs inside the container due to the melting and destruction of this container, the intervening substance having a boiling point below the melting temperature of the metal particles rapidly evaporates, causing volume expansion and pushing out the melted metal particles. And in a microgravity state, they exist as uniform bubbles in the molten metal powder.
That is, the entire molten metal powder expands along with the vaporization expansion of the intervening substance. Next, if the molten metal particles are cooled in the state of microgravity, the metal particles are solidified into a porous metal foam.

Then, it is possible to produce a foamed metal having an arbitrary porosity by selecting the amount of the intervening substance or the coefficient of vaporization expansion. Furthermore, the diameter of the pores can be arbitrarily controlled by appropriately selecting the diameter of the metal particles. Note that the microgravity state here includes a zero gravity state.

According to the invention described in claim (2), the mixture is heated to dissolve the metal powder, and the boiling point is equal to or higher than the melting temperature of the metal powder at the same time as or after the dissolution of the metal powder. Is vaporized, the container is destroyed by the vaporization of the intervening substance, and then the molten metal is cooled and solidified. As a result, the intervening substance causes volume expansion and pushes out the melted metal particles, and also exists as uniform bubbles in the melted metal particles. Is cooled and solidified to form a porous metal foam body. Since each of these steps is performed in a state of microgravity, the molten metal powder fluid does not move based on gravity.

〔Example〕

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

1 to 3 show one example of an apparatus used for carrying out the present invention. In the figure, reference numeral 1 denotes a container, specifically, a bottomed tubular body made of lead. In this container 1, a mixture 4 composed of a metal powder 2 and an intervening substance 3 is accommodated. The metal powder 2 is specifically powdered lead having the same melting temperature as the container 1, and has a boiling point between the metal powder 2 and the temperature equal to or lower than the melting temperature of the metal powder 2. The mixture 4 is formed by intervening the intervening substance 3. Although water was used in this embodiment as the intervening substance 3, any substance which does not form an alloy or other impurities by causing a chemical reaction with the metal powder 2 may be used. Various organic,
Inorganic substances can be used.

The container 1 containing the mixture 4 homogeneously in this manner is hermetically closed at the opening by the fastener 5, and is immovably mounted in the falling capsule 6 as shown in FIG. In the closed space 6a of the falling capsule 6, an electric furnace is formed by installing a heater 8 as a heating device inside a heat insulating material 7 as shown in FIGS. 8 is, for example, 2
It is divided so that it can be easily slid outwardly (in the X direction in the figure), so that the volume increase due to the vaporization of the intervening substance 3 is not hindered. 6b shows a power supply and a controller.

 Next, the operation will be described.

The container 1 containing the mixture 4 composed of the metal powder 2 and the intervening substance 3 is contained in the heater 8 of the falling capsule 6,
It is previously heated to a temperature slightly lower (about 10 ° C.) than the temperature at which the metal powder fluid 2 dissolves, and the temperature is maintained. Such a falling capsule 6 is lifted to a suitable height h (actually 50 m) from sand 10 in a sand box 9 installed on the ground surface GL as shown in FIG. 3, and then the falling capsule 6 is cut off. Free fall.

Immediately after the falling capsule 6 is cut off, the metal powder 2 and the container 1 are heated and melted using the heater 8, and thereafter, the power supply to the heater 8 is stopped. Since the pressure drop occurs inside the container 1 due to the melting and destruction of the container 1, the intervening substance 3 having a boiling point lower than the melting temperature of the metal powder 2 rapidly evaporates, causing the volume expansion and melting of the dissolved metal powder. The metal particles 2 melted because the particles 2 are spread out and in a state of microgravity
Exists as a uniform foam inside. In other words, in the microgravity state, the molten metal powder 2 hardly moves on the basis of gravity and expands as a result of the intervening substance 3 evaporating and expanding. During this expansion, the heat insulating material 7 and the heater 8
However, while taking into account not to hinder the expansion of the entire metal powder 2, it promotes the introduction of cold air outside the heat insulating material 7 into the heater 8, and rapidly cools and solidifies the molten metal powder 2. Let it. As a result, the metal powder 2 is formed into a porous foam metal body. The shape of the container 1 also functions as a mold.

By selecting the amount of the intervening substance 3 or the coefficient of vaporization expansion, it is possible to produce a foamed metal having an arbitrary porosity. Further, the diameter of the pores can be arbitrarily controlled by appropriately selecting the diameter of the metal particles 2.

In a microgravity environment, the molten metal particles 2 hardly move due to the difference in specific gravity from the intervening substance 3, so that the container 1 has a higher melting temperature than the metal particles 2. The container 1 can be made of a substance, and the container 1 can be melted and destroyed after the metal powder 2 is reliably melted.

The microgravity state described above is imparted by the free descent of the aircraft, and it goes without saying that the same action can be obtained even in a completely zero gravity state.

FIG. 4 shows another example of the apparatus used for carrying out the present invention. In this device, the container 11 contains the intervening substance 13 described below.
The container 11 is made of a material (for example, aluminum foil or paper) which is easily destroyed by vaporization. This mixture 14 is formed between the metal particles 12.
An intercalating substance 13 having a boiling point equal to or higher than the melting temperature of the metal powder 12 is penetrated and interposed.

The container 11 containing the mixture 14 is contained in the heater 8 in the closed space 6a of the falling capsule 6 in the same manner as in the above-described apparatus.
Next, a microgravity state is applied to raise the temperature of the mixture 14 to dissolve the metal powder 12, and simultaneously or after that, the intervening substance 13 is vaporized, and the container 11 is destroyed with this vaporization. When the container 11 is made of paper, it is desirable to replace the air in the closed space 6a with nitrogen gas to prevent combustion. Thus, since the intervening substance 13 expands and expands the dissolved metal particles 12 due to volume expansion, and because it is in a state of microgravity, it becomes present as uniform bubbles in the dissolved metal particles 12, When the molten metal is cooled and solidified in the microgravity state, a porous foamed metal body is formed.

〔The invention's effect〕

As will be understood from the above description, according to the present invention, a foamed metal body can be easily obtained simply by mixing a metal powder and an intervening substance, heating and melting the mixture in a microgravity state, and then cooling. Can be manufactured. In other words, just homogenize the metal powder and the intervening substance and give them uniform heating,
A high quality foamed metal body can be easily manufactured as compared with a method of manufacturing on the ground. And since the foamed metal body can be obtained easily and homogeneously, it is lighter and stronger than sintered material, etc., 80-90%
It is also possible to obtain a high porosity, and it is suitable for use in aircraft members, automobile members and the like as a material replacing the sintered material, the honeycomb structure material and the like.

[Brief description of the drawings]

1 to 3 show an example of an apparatus used for carrying out the present invention, FIG. 1 is a sectional view showing a main part of the apparatus, FIG. 2 is a partial sectional view showing a falling capsule, and FIG. FIG. 4 is a sectional view similar to FIG. 1 showing another example of the device used for carrying out the present invention. 1,11: container, 2,12: metal powder, 3,13: intervening substance, 4,14: mixture, 6: falling capsule, 7: heat insulating material, 8: heater (heating device).

Claims (2)

(57) [Claims] An intermediary substance having a boiling point lower than the melting temperature of the metal powder is interposed between the metal powders to form a mixture, and the mixture is melted at a temperature higher than the melting temperature of the metal powder. It is housed in a container having a temperature in an airtight manner, and in a microgravity state, the container is heated to melt the metal powder and the container and to vaporize the intervening substance, and then to cool and solidify the molten metal. A method for producing a foamed metal. 2. A mixture is formed by interposing an intervening substance having a boiling point equal to or higher than the melting temperature of the metal powder between the metal powders, and the mixture is destroyed by vaporization of the intervening substance. A foamed metal foam, which is housed in a container airtightly, and in a microgravity state, the temperature of the mixture is raised to dissolve the metal powder and vaporize the intervening substance, and then the molten metal is cooled and solidified. Production method.