JPS62294104A - Production of porous metallic body - Google Patents

Abstract

PURPOSE:To continuously produce a porous metallic body having a desired porosity by depositing a group of long metallic fibers having a specified aspect ratio on a belt conveyor and by pressing the resulting strip of fibers at the end of the conveyor. CONSTITUTION:A group of long metallic fibers contg. >=90% metallic fibers of Al or the like having <=250mum diameter and >=1,000 aspect ratio is produced by melt spinning. The group 1 of metallic fibers is continuously dropped on a belt conveyor 1 and the resulting strip of fibers is pressed with press rolls 3 at the end of the belt conveyor 2 to obtain a porous metal strip having 30-90% porosity. By this method, the porosity can be easily controlled and a product fit for the purpose for which it is used can be obtd.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a porous metal body that has a wide range of uses such as sound absorbing materials and electromagnetic shielding materials.

<Prior art and its problems> Porous metal bodies that are highly heat resistant and have good thermal and electrical conductivity have many uses including sound absorbing materials and electromagnetic shielding materials. Conventionally, this porous metal body has been obtained by a sintering method. In manufacturing by the sintering method, only starting materials (such as fine powder or so-called short fibers with a small aspect ratio) can be used, so the porosity of the resulting porous metal body is about 50% at most, and it cannot be too large. Moreover, it was difficult to control the porosity.Furthermore, the porous metal body obtained by the sintering method is semi-rigid and has no flexibility, so its shape cannot be changed freely, so it is used for sound absorbing materials etc. This is extremely inconvenient.

<Means for Solving the Problems> In order to solve the above-mentioned problems, the present invention adopts a method of forming metal fibers into a molded body only by press molding. In the following, a long metal fiber group containing 90% or more of the total metal fibers with an aspect ratio of 1000 or more is obtained, the long metal fiber group is dropped and deposited on one end of a belt conveyor, and press-formed at the other end of the belt conveyor. This is a method for producing a porous metal body having a porosity of 30 to 90%.

The material for the metal fibers used in the method of the present invention is not particularly limited, but materials with low melting points such as aluminum, zinc, and alloys thereof are usually used.

This metal fiber is manufactured by the method disclosed in Japanese Patent Application Laid-open No. 59-82411 previously filed by the applicant, but when adopting the method of rapid solidification in the atmosphere as shown in the publication of , if its diameter is larger than 250 μm, its cross section will not maintain a circular shape (so the diameter should be set to 250 μm).
m or less. In addition, the larger the aspect ratio (length to diameter) of the metal fibers, the more easily the metal fibers become entangled with each other. It was confirmed that it needs to account for more than 90% of the total.

Next, regarding the porosity of the porous metal body obtained by the present invention, if it is less than 30%, the pressure during press molding will be too excessive, and if it exceeds 90%, the porous metal body will be 30-90% because it cannot keep its shape.
And so.

<Example and operation> Using molten aluminum, JP-A-59-8241
Using the method shown in Publication No. 1, the diameter is 100 μm.

Aluminum fibers with an average fiber length of 64 cm were produced. A porous metal body was manufactured from the aluminum fiber thus obtained by roll pressing using an apparatus as shown in FIG. That is, the aluminum fiber (1) is fed at a feed rate of 1
It is continuously dropped at a rate of 200 g per minute onto a belt conveyor (2) moving at 22 cm/win to form an aluminum fiber band with a width of 45 cm on the belt conveyor (2). At the end of the process, it was pressed using a press roll (3) to form a porous aluminum body with a thickness of 1 mm.

Note that (4) in FIG. 1 indicates a guide roll, and (5) indicates a winding roll.

The porous aluminum body obtained in this example has a porosity of 87% and a specific gravity of 0.36, exhibits the flexibility of felt and the strength of Japanese paper, and can be easily cut with commercially available scissors. was completed. This porous aluminum body (
Figure 2 shows the measurement data of the electromagnetic shielding characteristics of the composite material (200X 200X 1mm) and epoxy resin (200X 200X 3n+m). It can be seen that the electric field shield attenuation value is 40 dB or more above 70 M[(z), and the magnetic field shield attenuation value is 40 dB or more above 150 MHz, both of which are weak.

Further, the above aluminum fiber (1) was fed at a feeding speed of 32 cm/m.
Belt conveyor (2) running at 70 per minute
It was dropped continuously at a rate of 0 g, and transferred to a belt conveyor (2
) was formed with an aluminum fiber band having a width of 45 cm and pressed using a press roll (3) at the end of the belt conveyor (2) to form a porous aluminum body having a thickness of 311I+1.

The porous aluminum body obtained in this example had a porosity of 40% and a specific gravity of 1.62.

Figure 3 shows measurement data of the sound absorption properties of this porous aluminum body.

From Figure 3, it is 550 to 190 when the back air layer is 25 mm.
0112 area, 350 to 1 when the back air layer is 50 mm
300)! It can be seen that there is a sound absorption coefficient of 60% or more in the z region.

In the above embodiments, a roll press was used for press forming, but any type of press may be used without being limited to a roll press.

<Effects of the Invention> As described above, according to the method of the present invention, the process from manufacturing metal fibers to manufacturing porous metal bodies can be carried out continuously, compared to the batch method of conventional sintering methods. Therefore, it is suitable for mass production. In addition, in the present invention, since long metal fibers with a large aspect ratio are used as raw materials, the metal fibers are entangled with each other to form a molded product simply by pressing, so the diameter and length of the metal TA fibers or the press forming pressure can be adjusted. By doing so, the porosity can be easily controlled and the product can be made suitable for the purpose of use.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of the apparatus used in the embodiment of the present invention;
FIGS. 2 and 3 are graphs showing electromagnetic shielding characteristics and sound absorption characteristics, respectively, of the porous aluminum body obtained in the same example. In the figure: (1) Aluminum fiber (2) Belt conveyor (3) Press roll (4) Ni guide roll (5) Take-up roll
000/C, 1 frequency (Hzl

Claims (1)

[Claims] 1. A long metal fiber group containing 90% or more of the total metal fibers with a diameter of 250 μm or less and an aspect ratio of 1000 or more is obtained by a melt spinning method, and the long metal fiber group is dropped and deposited on one end of a belt conveyor. A method of manufacturing a porous metal body having a porosity of 30 to 90% by press forming at the other end of the conveyor.