JPS61250126A - Manufacture of porous aluminum - Google Patents

Abstract

PURPOSE:To obtain porous Al having strong binding force, high ductility and free from mixed foreign matter and remaining thereof, by coating slurry such as water of K3AlF6 salt on surface of linear etc. material of Al alloy having large temp. difference between solid and liquid phases, drying the material then put it into compacting mold to heat, weld and bind the materials with each other. CONSTITUTION:Linear, chip or fiber shaped material of alloy systems of Al-Si, Al-Cu, Al-Mg, Al-Si-Cu, Al-Mg-Si, Al-Zn-Mg, Al-Sn and Al-Pb in which difference between solid and liquid phase temps. is large is used. Slurry of water or volatile soln. of powdery K3AlF6 salt flux is coated on surface of the material and dried them, it is put in compacting mold, heated by heating furnace to temp. range of solid and liquid phases of material, to weld and bond metallographically the materials with each other. About 60-90% solid phase ratio is desirable in temp. range of solid and liquid phases of material.

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. It takes several hours to carry out the process, and if there is dirt or foreign matter on the contact surface, the diffusion rate is extremely reduced, the bonding force between the metals is weakened, and the mechanical properties are deteriorated.

In addition, as a manufacturing method that utilizes the porosity of other materials, metal is attached to the surface of expanded polystyrene using a surface treatment method such as electrodeposition, 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 each method has disadvantages such as the risk of styrofoam oxides and sodium chloride particles remaining inside the porous metal, and low mechanical strength because the metal body is thin. there were. Note that the lightweight particle diffusion method has almost no porosity and is not a true porous metal.

Furthermore, in the production method (foaming method) in which a gas-generating substance is placed in the molten metal and pores are scattered inside the metal body, gas-generating compounds such as magnesite, Ti, and hydrides of 2' are added to the molten metal. In this process, the gas content of the molten metal is supersaturated and solidified to incorporate pores to obtain a porous metal, but the location of the pores varies, 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, and the solidification rate also depends on the size of the pores, which has the disadvantage that the presence of pores is uneven and the quality is unstable.

Furthermore, when bonding separated metals, when the metals are in a solid state, energy is added to remove the oxide coating the metal and to diffuse the metal atoms. must be in a high temperature, high pressure atmosphere. 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 i-oxide coating the metal surface is chemically removed using flux, and then heated to diffuse the metal atoms and bond. 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 technology.
i-based alloy, AI-Cu-based alloy and Al-Mg-based alloy, or AI-Si-Cu-based alloy, AI
-M g -S i alloy, A I -Z n -M
g-based alloys, AI-S n-based alloys, Al-P-
After applying an aqueous slurry of a powdered flux of potassium aluminum fluoride or a slurry of a volatile solution to the surface of a linear, chip-shaped or fibrous material of B-based alloy and drying it, place it in a mold for forming. The method of heating the above-mentioned alloy materials in a heating furnace to a temperature range between the solidus temperature and the liquidus temperature and fusing the wire, chip, or fibrous materials together to form a metallic bond creates a strong metallic bond, and the metal interior The present invention provides a method for producing porous aluminum in which no foreign matter remains.

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 A I-S i alloy. Looking at the temperature properties of the aluminum-based aluminum alloy in Figure 1, the temperature range (upper limit temperature... There are three states: a temperature range where solid and liquid coexist (upper limit temperature...liquid phase aS degrees), and a temperature where everything is in a liquid state (above liquidus temperature).

The present invention focuses on the above-mentioned temperature characteristics of aluminum alloys, and the temperature range in which the solid phase and liquid phase coexist is required to bond the metal materials together without destroying their shape. It has been found that the temperature at which the solid phase ratio (amount of solid phase/(amount of solid phase + liquid phase)) is 60 to 95% is most suitable.

At the solid phase ratio, the metals in the liquid phase partially eluted from the adjacent metal materials 1 and 2 are in a state where atoms are most easily diffused, so they easily fuse, and since the solid phase ratio is high, The metal skeleton is in a state before it is strongly heated. Therefore, if the metal materials 1m and 2a are cooled immediately after being heated to the above-mentioned solid phase ratio, the unfused liquid phase portions 1m and 2a will solidify and the adjacent metal materials 1 and 2 will be bonded together as shown in FIG.

The optimum range of the above solid phase ratio is 60 to 90%, but when the solid phase ratio is 95% or more, there is little liquid phase to be eluted, and the probability that metals that are in mechanical 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 solid phase ratio is less than 60%, the amount of liquid phase eluted is large;
It flows out to the lower layer due to gravity and fills the gaps between the intertwined metals, making it impossible to obtain a homogeneous porous metal.

Next, embodiments of the present invention will be specifically described based on the above-mentioned principle. First, AI-Si alloy (Al-5%
Continuously cast billets (diameter 100φ) of Si) are lathe-processed to have an average width of 1-1, an average length of 300 mm, and an average thickness of 0.
31) Obtain Ill fibrous material.

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 with a nitrogen gas atmosphere and heated to a temperature (590°C to 605°C) at which the solid phase ratio is 60 to 95%. When the mold reaches the above temperature, the mold is The porous aluminum is taken out from the heating furnace, forced air cooled, and then taken out from the mold.

In addition, the heating temperature of the above AI-Si alloy is 59C.
'r' to 605°C, but the heating temperature in the case of AI-Cu alloy is 570°C to 600°C, and the heating temperature for Al-Mg
The heating temperature in the case of alloys is 570°C to 590°C.

Also, A I -S i -Cu alloy, Al-M g
-Si type alloy, A I -Z n -M g type alloy, the heating temperature is 490 to 550 °C, and Al-3n
The heating temperature for Al-Pb alloys is 200~200℃.
The temperature is 300°C. Here, Al-CU alloy, Al-M
When a g-based alloy is used, the only difference is the heating temperature and the other conditions are the same as the above-mentioned A I-S i-based alloy. Further, although a heating furnace with an inert gas atmosphere was used in the above embodiments, any one of a normal heating furnace, a vacuum heating furnace, and a combination of a heating furnace with an inert gas atmosphere 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 slurry of an 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, a square, a triangle, a 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.

B Heating and holding times are shorter than conventional sintering methods,
Productivity can be improved and prices can be reduced.

Mouth 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 arbitrarily changed by simply changing the shape of the material, and the control range is wide.

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

E) There is very little foreign matter contamination or foreign matter remaining.

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

G. High electrical conductivity and high current collection effect.

[Brief explanation of the drawing]

FIG. 1 is a binary phase diagram of an A j -S i alloy that is an embodiment of the present invention, and FIG. 2 is a diagram of the principle of the present invention. 1.2...metal material, la, 2a...liquid phase part, 3.
...Contact section patent applicant: Nippon Light Metal Co., Ltd., agent: Hideaki Sato, patent attorney: Hideo Ohashi, patent attorney

Claims (5)

[Claims] (1) Al-Si alloy, Al-Cu alloy, Al-Mg alloy, Al-S with a large difference between solidus temperature and liquidus temperature
i-Cu alloy, Al-Mg-Si alloy, Al-Zn
- Apply an aqueous slurry of a powdered flux of potassium aluminum fluoride salt or a slurry of a volatile solution to the surface of linear, chip-like or fibrous materials of Mg-based alloys, Al-Sn-based alloys, and Al-Pb-based alloys. After drying,
It is characterized by being placed in a mold and heated in a heating furnace to a temperature range between the solidus temperature and liquidus temperature of the above alloy material, thereby fusing the linear, chip or fibrous materials together to form a metallic bond. A method for producing porous aluminum. (2) The method for producing porous aluminum according to claim (1), wherein the solid phase ratio is 60 to 90% in the temperature range of the solid phase concentration and liquidus temperature of the alloy material. (3) Claim No. (1) in which the heating temperature of the Al-Si alloy in the heating furnace is 590°C to 605°C.
The method for producing porous aluminum as described in Section 1. (4) Claim No. 1, wherein the heating temperature of the Al-Cu alloy in the heating furnace is 570°C to 600°C.
The method for producing porous aluminum as described in Section 1. (5) Claim (1) in which the heating temperature of the Al-Mg alloy in the heating furnace is 570°C to 590°C.
The method for producing porous aluminum as described in Section 1.