JPS60238431A - Manufacture of porous aluminum - Google Patents

Abstract

PURPOSE:To obtain the titled porous Al having strong metallic binding force without any foreign materials remaining in the metal by heating a linear, chipped, or fibrous material of an alloy of Al-Si, etc. having large difference between the solid-phase temp. and the liquid-phase temp. in a metallic mold to a specified temp. CONSTITUTION:A slurry of powdery potassium fluoride in water or in a volatile soln. is coated on the surface of a linear, chipped, or fibrous material of an Al-Si, Al-Cu, or Al-Mg alloy having a large temp. difference between the solid and the liquid phase, and dried. The dried material is then charged into a metallic mold for molding, and the mold is placed in a heating furnace contg. a gaseous N2 atmosphere and heated to a temp. ranging from the solid phase temp. to the liquid phase temp. of said alloy metal. In this case, the temp. at which about 60-95% solid phase is obtained in optimum, and the liquid metals which are partially melted out from adjacent metallic materials 1 and 2 melt into each other. Since the solid-phase percentage is high, the skeleton of the metal is strong and is in the same conditions as that before heating. Accordingly, the liquid phase parts 1a and 2a which are melted into each other are solidified by cooling immediately after the heating to said temp., and the materials 1 and 2 are fused together.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing porous aluminum. Conventionally, various means have been provided as methods for producing porous metals. In other words, the method for producing porous metals by sintering is a method that utilizes the diffusion phenomenon of metal atoms due to external thermal energy at the interface of two contacting powder metals. This process takes several hours, and the presence of dirt or foreign matter on the contact surface dramatically reduces the diffusion rate, weakens the bonding force between metals, and deteriorates mechanical properties.

In addition, as a manufacturing method that utilizes the porosity of other materials, metal is attached to the surface of expanded polystyrene using an electrodeposited ring surface treatment method, and then the expanded polystyrene is burned to obtain a mesh-like porous metal (incineration method). ) Alternatively, water-soluble particles such as sodium chloride are sintered into a predetermined shape, molten metal is injected under pressure into the gaps between the particles, and after solidification, the sodium chloride is dissolved in water to obtain a mesh-like porous metal. There is a method (elution method), but there is a risk that styrofoam oxides and sodium chloride particles remain inside each λ porous metal, and the metal body is thin, so it has low mechanical strength. was there. Note that the light particle diffusion method has a porosity of tl and is not a true porous metal.

Furthermore, in the manufacturing method (foaming method) in which a gas-generating substance is placed in the molten metal to create pores inside the metal body, gas-generating compounds such as magnesite and hydrides of Ti and ZR are added to the molten metal. Porous metal is obtained by supersaturating the scum content of the molten metal and solidifying it to incorporate pores, but there are variations in the location of pores, and the temperature distribution of the molten metal, especially near the bottom of the furnace and near the surface of the molten metal, is obtained. There is a large temperature difference between the two metals, and the solidification rate also depends on the size of the pores. A high temperature, high pressure atmosphere is required to remove the oxides contained therein and to provide the energy addition necessary to diffuse the metal atoms. In this case, the application of high temperature makes the gaps between the metals very dense, so it is not suitable for bonding the metals together and obtaining a porous metal that requires large gaps.

Another method of bonding separated metals is a type of brazing method in which the oxide coating the metal surface is chemically removed using flux, and the metal atoms are diffused and bonded by heating. The mechanical bonding strength was weak, and the bending workability and impact resistance were poor.

The present invention has been made in view of the above-mentioned drawbacks of the conventional art. After applying an aqueous slurry of a powdered flux or a slurry of a volatile solution of potassium aluminum fluoride to the surface of a chip-shaped or fibrous material and drying it, the alloy material is placed in a mold and heated in a heating furnace. The method of heating wire, chip, or fibrous materials to a temperature range between the solidus temperature and the liquidus temperature to form a metallic bond creates a strong metallic bond, and there is no residual foreign matter inside the metal. A method of manufacturing a porous aluminum is provided.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1st
The figure is a binary phase diagram of the Al-Si alloy. Looking at the temperature properties of aluminum-based aluminum alloys in Figure 1, we can see that the temperature range in which the solid state remains (upper limit temperature... There are three states: a temperature range where solid and liquid are mixed (upper limit temperature...liquidus temperature), and a temperature where everything is in a liquid state (above the liquidus temperature).

The present invention focuses on the above-mentioned temperature characteristics of aluminum alloys, and uses low 4O1-4G to bond metal materials together without destroying their shapes.
xl-” de S1~--1. Fuco W-It, ■IZEII
r, sea 1--yGllaJa rate [amount of solid phase/(solid phase +
It has been found that the temperature at which the amount of liquid phase) is 60 to 95 degrees is most suitable.At this solid phase ratio, the metals in the liquid phase partially eluted from the adjacent metal materials 1.2 The atoms are in the state where they are most easily diffused, so they fuse easily,
Also, since the solid phase ratio is high, the metal skeleton is in a state before being strongly heated. Therefore, after heating to the above solid phase ratio,
If it is cooled immediately, it will fuse and form the large liquid phase part 1a.

- 2a solidifies and the adjacent metal materials 1 and 2 are bonded together as shown in FIG.

The optimal range of the above solid phase ratio is 60 to 90 inches, but when the solid phase rate is 95 inches or more, there is less liquid phase to be eluted, and the probability that metals in mechanical pressure contact will fuse at the contact part 3 is low. As a result, it cannot be expected that all contact areas will be fused, and some areas will have poor fusion, making it easier for the metals to separate after solidification and cooling.

On the other hand, when the in-phase ratio is less than 60 cm, the amount of liquid phase eluted is large;
A homogeneous porous metal cannot be obtained because the metal flows to the lower layer due to gravity and fills the gaps between the intertwined metals. Explain. First, AJ-8a alloy (AI!-5% S
T) Continuously cast billet (diameter 100φ) is lathe-processed to produce an average width of 1 inch, average length of 3001111, and average thickness of 0.
．． Three types of fibrous material are obtained. Next, this fibrous material is degreased with ethyl alcohol, washed, dried, and then put into a mold. This mold is placed in a heating furnace in a nitrogen gas atmosphere at a temperature (590°C to 605°C) at which the in-phase ratio becomes 60 to 95%.
℃), and when the mold reaches the above temperature, the mold is taken out from the heating furnace, forced air cooled, and then the porous aluminum is taken out from the mold.

The heating temperature of the above AJ-8t alloy is 590°C to 6°C.
05°C, the heating temperature in the case of A/-Cu alloy is 570°C to 600°C, and the heating temperature in the case of hl-Mg alloy is 570°C to 590°C. When using hl-Cu alloy or AJ-Mg alloy, the above AI!
The only difference is the heating temperature from the -8L alloy, and the other conditions are the same. Furthermore, although a heating furnace in an inert gas atmosphere was used in the above embodiments, any heating furnace that is a combination of a heating furnace and a vacuum heating furnace may be used. Further, in the above embodiment, the material was degreased with ethyl alcohol, washed, and dried, but any aqueous slurry of a powdered flux of potassium aluminum fluoride salt or a slurry of a volatile solution may be used. Further, the shape of the porous aluminum product can be formed into a desired shape such as a circle, square, triangle, polygon, etc. using a mold.

As explained in detail above, since the present invention is the above-mentioned manufacturing method, it has the following effects.

←) Heating and holding time are shorter than conventional sintering methods,
Productivity can be improved and prices can be reduced.

(b) Mechanical properties, especially (elongation), are high. Conventional baked crystals and foamed metals are brittle and have poor workability, whereas the products obtained by the present invention are ductile and can be easily bent, cut, etc.

(c) In the case of the conventional method, the pore diameter and porosity depend on the manufacturing method and the effective range is narrow, but according to the present invention, the pore diameter and porosity can be changed arbitrarily by simply changing the shape of the material. The control range is wide.

- Since it has a strong metal bond, it is resistant to heat shock and can be welded, for example.

(e) There is very little foreign matter contamination or foreign matter remaining.

(f) The heat transfer coefficient is improved due to a significant increase in the heat transfer area.

(g) Good electrical conductivity9, high current collection effect.

[Brief explanation of the drawing]

FIG. 1 shows AI! which is an embodiment of the present invention. The binary phase diagram of -8a alloy, FIG. 2, is a principle diagram of the present invention. 1.2...metal material, la, 2a...liquid phase part, 3.
...Contact part patent applicant Nippon Light Metal Co., Ltd. Agent Patent attorney Hide Sato Akiramo Mouth size 21 Diagram

Claims (1)

[Claims] fil AJ-8 with a large difference between solidus temperature and liquidus temperature
Applying an aqueous slurry or a slurry of a volatile solution of powdered fusix of aluminum fluoride potassium salt to the surface of linear, chip-like or fibrous materials of i-based alloys, AJ-Cu-based alloys, and Al-Mg-based alloys. 1. A method for producing porous aluminum, which comprises drying it, placing it in a mold, and placing it in a heating furnace for metallurgical bonding. (2) The method for producing porous aluminum according to claim (1), wherein the solid phase ratio is 60 to 90% in the temperature range between the solidus temperature and the liquidus temperature of the alloy material. (3) Claim (1) in which the heating temperature of the Al-8i alloy in the heating furnace is 590°C to 605°C.
The method for producing porous aluminum as described in Section 1. (4) In the heating furnace, the heating temperature of the Al-C, u-based alloy is 570°C to 600°C.
1) The method for producing porous aluminum as described in section 1). (5) In the heating furnace, the heating temperature of the Al-Mg alloy is 570°C to 590°C.
) The method for producing porous aluminum according to item 1.