JPH03294437A - Manufacture of metallic material having pore - Google Patents

Abstract

PURPOSE:To lighten a metallic material in weight and to improve its thermal insulating properties and noise reduction properties by finishing the working or casting of a slurried metal having a solid-liquid mixed phase in the state where the liquid phase remains and immanently dispersing fine pores formed by the solidification and shrinkage of the remaining liquid phase or the like into the substance of the solidified body. CONSTITUTION:Metallic molten metal 10 in a wide sense including alloys is fed to the pouring cup 1a of a stirring and cooling bath 2 and is cooled while stirring is executed by the rotation of a stirrer 4. Next, the above slurried metal 12 is continuously drained from a drain nozzle 3 and is subjected to working or casting, and the above working or casting is finished in the state where a liquid phase remains. Then, fine pores formed by the shrinkage of the above remaining liquid phase in accordance with its solidification and the reduction of gas solubility are inherently dispersed into the substance of the solidified body. In this way, a metallic material in which pores are largely dispersed is obtainable, by which the lightening of structures is permitted and the improvement of capacities such as thermal insulating properties and noise reduction properties can furthermore be obtd.

Description

[Detailed description of the invention] (Industrial application field) With the progress of science and technology and the development of industry, metal materials with new functions are required, and improvements such as weight reduction, heat insulation properties, and sound deadening properties of metal materials are required. is one example.

Among these, there is a strong need to reduce the weight of metal materials, especially for materials used in various devices, from the perspective of energy conservation that contributes to global environmental conservation.

To reduce the weight of metal materials, switching from steel to aluminum, a lighter metal, is an option, but this is not always the case if the price, material properties, etc. are satisfactory.

Powder metallurgy techniques are also known in which materials with low specific gravity, such as ceramics, are mixed in order to reduce the weight of metal materials, but their use is severely limited due to poor processability.

The following describes the results of research and development on a method for manufacturing metal materials with pores that can advantageously meet the demands for improvements in heat insulation, sound deadening, etc., as well as weight reduction of the metal materials mentioned above.

(Prior art) In general, metal materials are usually processed by leaving the molten metal in a mold or solidifying it in a similar state, and then processing it. There are almost no pores present.

On the other hand, there has been an attempt to obtain an ingot with bubbles by blowing gas into the bath while the metal material is in a molten state and casting it directly into a mold. Gas bubbles easily float up in the bath and become dispersed, and gas bubbles coalesce during floating to form large bubbles that are rather harmful.
The number of pores remaining in the ingot is small and their size varies widely.

On the other hand, in recent years, a number of proposals have been made regarding methods of manufacturing slurry metal, but none of them include the concept of actively incorporating pores in the manufacturing and processing process of slurry metal.

Metal materials manufactured by the conventional techniques described above do not contain pores in a dispersed state, although they may sometimes contain pores in some heterogeneous parts, and therefore do not actively contain pores in a dispersed state. This is due to the fact that no conventional technology has been found for dispersing and incorporating it into the substance of a coagulated body.

(Problem to be Solved by the Invention) In order to advantageously achieve improvements such as weight reduction or insulation of metal (in a broad sense including alloys, etc.) material, as well as sound-deadening properties, fine particles are incorporated into the substance of the solidified body. It is an object of the present invention to establish a method for producing a metal material having pores, which is characterized by incorporating air bubbles in a dispersed state.

(Means for Solving the Problems) This invention processes or casts a metal in a state in which a solid phase is scattered in its liquid phase, and finishes the above-mentioned processing or casting in a state in which the liquid phase remains, This is a method for producing a metal material having pores, which is characterized by dispersing and incorporating micropores in the substance of a solidified material, which are caused by shrinkage due to solidification of the remaining liquid phase and decrease in gas solubility. In this case, during cooling under stirring in the solid-liquid coexistence region, the liquid phase in which the solid phase of the metal is scattered is engulfed by the above-mentioned stirring of the gas atmosphere covering the surface of the hot water, or into the solid-liquid coexistence phase. It is particularly effective to include bubbles caused by gas injection.

This invention is derived from the findings listed below.

■A method for scattering fine pores in a product metal material is to apply pressure forming or casting to a slurry metal in which a solid phase is scattered in the liquid phase of the metal melt, and the liquid phase remains. By completing the pressurization or casting in a state where it is completely solidified after molding, it is possible to incorporate fine pores due to the solidification shrinkage in the liquid phase region and the generation of air bubbles from the gas due to the decrease in gas solubility. ■Increase the amount of pores. As a method, we focused on the phenomenon of air being entrained from the surface of the hot metal during stirring during the production of slurry-like metals in which solid and liquid coexist, and by creating an appropriate gas atmosphere instead of the atmosphere, we created a harmless gas. Immediately after that, by making it into a slurry form, it is made to remain in the slurry metal and processed or cast as shown in After that, it can be processed and molded to produce a product containing a large amount of pores.

■As a means to further increase the amount of pores, in the method shown in (■), by further blowing an appropriate gas into the molten metal or slurry, the air bubbles are made to be present in the slurry metal.
It is possible to produce a product having a larger number of pores by processing or casting it as shown in (2), or by solidifying the slurry metal and then processing and forming it.

(Function) The solid phase scattered in the liquid phase prevents the gas dissolved in the metal melt from being released from the liquid phase due to the decrease in gas solubility due to the temperature drop of the melt. The basic action is to finish processing or casting in a solid-liquid mixed phase in a state where it can be captured, and to leave it as micropores due to subsequent contraction due to solidification, and the metal slurry as a solid-liquid mixed phase It is more likely that a large amount of pores will remain due to the dispersion of a harmless gas such as an inert gas from the atmosphere of the stirring operation during the cooling process to generate the metal slurry or into the metal slurry during cooling and stirring. It is a developmental effect.

Now, FIG. 1 illustrates the specific configuration of the cooling stirring tank used for carrying out the present invention, where 1 is a receiving tank, 2 is a cooling stirring tank, and 3 is a cooling stirring tank.
4 is a discharge nozzle, 4 is a stirrer, 5 is its drive shaft, 6 is a stirring gap, 7 is a lid, 8 is an atmospheric gas supply pipe, and 9 is a blown gas supply pipe.

Here, molten metal lO is continuously supplied to the inlet port 1a, and the drive shaft 5
Slurry metal is continuously produced through the stirring gap 6 between the stirrer 4 connected to the stirrer 4 and the stirring cooling tank 2. At this time, as the stirrer 4 rotates, the surface 11 of the hot water in the receiving tank 1 becomes concave as shown in the figure, and the flow of the hot water surface 11 becomes turbulent. This turbulence causes atmospheric gas to be drawn in.

Therefore, as shown in the figure, a lid 7 is installed on the top of the molten metal receiving tank 1, and a harmless gas, such as an inert gas, is sent from the atmosphere gas supply pipe 7 passing through the lid 7, thereby controlling the atmosphere inside the molten metal receiving tank 1. The gas is drawn in by utilizing the turbulence of the hot water surface 11.

Along with this or separately, a blowing gas supply pipe 9 is provided in the stirring cooling tank 2 so as to open into the stirring gap 6, and by blowing the gas, bubbles are uniformly generated in the slurry metal.

The metal slurry discharged from the discharge nozzle 3 has a solid phase scattered in the metal liquid phase, so it is processed or cast, and the liquid phase remains.11''?: The above processing or casting is completed. Thus, due to the contraction of the remaining liquid phase and the decrease in gas solubility as it solidifies, pores are dispersed within the substance of the solidified material.

(Example) A ff1-10% Cu alloy was supplied as a molten metal to the inlet port 1a of the cooling stirring tank shown in Fig. 1, and cooled while stirring at a rotational speed of the stirrer 4 at 50 Orpm to form an A1 alloy slurry. 12 was continuously discharged from the discharge nozzle 3.

At that time, 10Of Ar gas is supplied from pipe 8 of 10a+*φ.
/The interior of the diverted molten metal receiving tank 1 was set to an Ar atmosphere. Furthermore, Ar gas is supplied to the stirring cooling tank 2 from the 2-φ vibrator 9 at 10117°C.
I injected a minute.

A part of the cross section of a sample 16 obtained by solidifying the AI1 alloy slurry 12 obtained in this way into a block shape is shown in the schematic diagram of FIG. The pores 18 in which relatively large atmospheric gas and blown gas remained as bubbles were uniformly dispersed.

To supply the blown gas into the stirring cooling tank 2, a porous brick may be used at the tip instead of the tube end nozzle as shown in the figure. In this case, finer pores can be dispersed.

By increasing or decreasing the flow rate of the gas blown into the stirring cooling tank 2, it is possible to adjust the increase or decrease in the number of pores in the slurry metal. In the illustrated example, a mechanical stirring method is illustrated, but it goes without saying that when electromagnetic stirring is used instead, a slurry-like metal containing air bubbles can be obtained in exactly the same manner.

(Effects of the invention) In recent years, there has been a strong demand for lighter structures, such as automobiles, from the viewpoint of reducing energy consumption and preserving the global environment. The above requirements can be easily met by obtaining a metallic material and reducing the weight per unit volume.

Of course, the strength decreases due to the weight reduction, but it has been confirmed that the specific strength increases, which contributes to the weight reduction of the structure. In addition, metal materials containing pores have improved heat insulation and sound deadening properties.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a cooling stirrer that can be advantageously used in the method of the present invention, and FIG. 2 is a sample cross-sectional view (sketch) of a part of the sample block obtained by the method of the present invention. be. 1... Receiving tank 2 Stirring cooling tank 4... Stirrer 6... Stirring gap 8... Pipe 10... Molten metal 12... Slurry metal 14... Cooling water outlet 16... Block cut sample 18...pore 1a...molten metal inlet 3...discharge nozzle 5 rotation drive shaft 7...lid 9...pipe 11...molten water surface 13...cooling water population 15...・Cooling chamber 17...Minute pores Figure 1 Figure 2

Claims (1)

[Claims] 1. Processing or casting the metal in a state where the solid phase is scattered in the liquid phase, and finishing the above processing or casting with the liquid phase remaining, to remove the remaining liquid phase. 1. A method for producing a metal material having pores, the method comprising dispersing and incorporating micropores generated by shrinkage due to solidification and reduction in gas solubility into the substance of a solidified material. 2. In claim 1, when the liquid phase in which the metal solid phase is interspersed is cooled under stirring in the solid phase/liquid phase coexistence region,
A method for manufacturing a metal material having pores that includes air bubbles caused by entrainment of the gas atmosphere covering the surface of the hot water due to the above-mentioned stirring. 3. In claim 1, the liquid phase in which the metal surface phase is scattered contains bubbles due to gas injection into the solid-liquid coexistence phase during cooling under stirring in the solid-liquid coexistence region. A method for producing a metal material having pores comprising: