JP2014005495A - Metal material having hollow structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that although a casting method using a thickening material and a foam core material at the time of melting or a powder method mixing and molding a metal powder with a polymeric material are used as conventional methods for manufacturing a metal material having a hollow structure, control of cell morphology is impossible, the size of a void is milli order, and manufacturing of a metal powder is difficult and dangerous, to impart a hollow structure inside metal.SOLUTION: By adding particles having a hollow structure into a metal in a molten state at a suitable ratio, forming secondary particles having the hollow particles adhered around a metal particle by mixing, and adding the secondary particles to the molten metal at a suitable ratio and solidifying the resultant mixture by additional mixing, a metal material of which the cross section has an annular or dendritic hollow structure is formed.

Description

The present invention relates to a metal material having a hollow structure manufactured using particles having a hollow structure.

Metal materials with a hollow structure inside the gas have a lower density than materials without a hollow structure and have a structure that suppresses the transmission of heat and sound. And structural members capable of controlling acoustic characteristics and heat transfer characteristics.

As a conventional method for producing a metal material having a hollow structure, a casting method (Non-patent Document 1) for creating a hollow structure derived from a foam nucleating agent in a molten metal using a thickener and a foam nucleating agent at the time of melting. Alternatively, there is a powder sintering method (Non-patent Document 2) in which a polymer material is mixed with metal powder and molded.

As a casting method, after a metal is heated and melted, the temperature is lowered to give viscosity to the molten metal, and then a foaming agent is added to form a foamed molten metal in a foaming reaction state (Patent Document 1). There is a method (Patent Document 2) in which a thickener is added to a molten metal and stirred, a foaming agent is added to the molten metal, the foam is filled in a mold, and then rapidly cooled.

As the powder sintering method, a metal porous body is obtained by kneading metal powder, a binder, a water-soluble powder and a water-soluble polymer material, extracting the water-soluble powder and the water-soluble polymer material with water, removing it, and firing it. (Patent Document 3), a method of producing a porous metal material by securing the pore space with a spacer material, compression molding the metal and the spacer, and then removing the spacer (Patent Document 4), porous Of high-quality organic polymer material impregnated with a mixture of a dispersant-containing aqueous solution and metal powder, followed by drying and heating in a non-oxidizing gas atmosphere to degrease the organic polymer material and further sinter the raw material powder (Patent Document 5).

In addition, as a method for producing a porous material using particles, there is a method in which a microcapsule containing water coexists with a metal alkoxide, and a porous ceramic is produced by a hydrolysis reaction (Patent Document 6).

JP-A-7-233428 JP 2002-371327 A JP 2000-17349 A JP 2004-292888 A Japanese Patent Laid-Open No. 5-287329 Japanese Patent Application Laid-Open No. 6-293577 Japanese Patent Application No. 2010-282477

Acta Materialia, vol. 49, pp. 1677-1686, 2001. Advanced Engineering Materials, vol. 2, pp. 168-174, 2000. Scripta Materialia, vol. 65, pp. 827-829, 2011.

In the above background art, the method using a thickener and a foam core material at the time of melting makes it difficult to control the viscosity of the molten metal, so the cell form cannot be controlled, and the size of the hollow structure becomes as large as several millimeters. That is a problem.

The method of mixing and molding a polymer material with metal powder in the background art has problems that it is difficult and dangerous to produce metal powder and that it is difficult to produce a large molded product.

The method for producing porous ceramics using microcapsules in the background art described above uses solid microcapsules with water inside, and cannot directly create a hollow structure. There is a problem that there is no example of creation.

In order to solve such a problem, the present inventors have previously described "hollow structure by kneading and dispersing particles having a hollow structure therein in a molten metal and then solidifying the particles. Proposed a method for producing a metal material or metal particles having a metal oxide (Patent Document 7, Non-Patent Document 3).

In this method by the applicants, the silica hollow particles and molten metal are kneaded to form secondary particles, and then molten metal is added and kneaded to produce a metal material having a complicated cavity structure. In addition, it is said that the sound attenuation characteristic specific to the metal material is exhibited. However, Patent Document 7 shows only one example relating to the generation of a metal material having a cavity structure, and the conditions that show inherent acoustic attenuation and the generation conditions such as the size and porosity of the pores are acoustic attenuation characteristics. There is no clear description of the effects on

This invention makes it a subject to solve the problem regarding the metal which has the said conventional hollow structure.

As a result of intensive studies to achieve the above-mentioned object, the inventors of the present invention have already proposed the method described in Japanese Patent Application No. 2010-282477. Secondary particles in which particles having a hollow structure are held around or inside a metal formed by kneading particles of 1 to 100 μm in a state of containing 0.5% by weight or more of particles having a hollow structure with respect to the molten metal By further kneading the particles with 50% by weight or more of molten metal with respect to the secondary particles, a metal material having a hollow structure with a circular or dendritic cross section is generated.

With the metal material having a hollow structure according to the present invention, the following effects can be obtained. (1) If particles having a hollow structure and having a melting point equal to or higher than the melting point of the metal are added, the hollow structure can be easily provided in the metal material only by the kneading step. (2) By controlling the mixing ratio of the particle diameter having a hollow structure and the molten metal, the hollow structure shape and porosity of the metal material can be easily changed. (3) The strength and vibration damping characteristics of a metal having a hollow structure can be changed by changing the hollow structure shape and porosity of the metal material.

It is a diagram showing a configuration of the present invention, 2 is an optical microscope image of a cross section of a metal having a hollow structure obtained in Example 1. FIG. 3 is an optical microscope image of a cross section of a metal having a hollow structure obtained in Example 2. FIG. 4 is an optical microscope image of a cross section of a metal having a hollow structure obtained in Example 3. FIG. 4 is an optical microscope image of a cross section of a metal having a hollow structure obtained in Example 4. FIG. 6 is an optical microscope image of a cross section of a metal having a hollow structure obtained in Example 5. FIG. It is an optical microscope image of the cross section of the metal which has the hollow structure obtained in Example 6. It is the figure which showed the relationship between the porosity of the metal which has the hollow structure produced in Example 1 to Example 7, and the metal without a hollow structure, and compressive yield stress. It is the figure which showed the relationship between the porosity of the metal which has the hollow structure created in Example 1 to Example 6, and the sound transmittance in a 3 MHz-30 MHz band when the metal without a hollow structure is set to 1.

In the method for producing a metal material having a hollow structure in the present invention, secondary particles in which hollow particles are attached around metal particles by adding particles having a hollow structure in a molten metal at a suitable ratio and kneading. The particles are formed, the secondary particles are added to the molten metal at a suitable ratio, and further kneaded to solidify to produce a metal material having a hollow structure with a circular or dendritic cross section. . Hereinafter, the best mode for carrying out the present invention will be described with reference to FIG.

In the best mode for carrying out the present invention, the metal 2 and the particles 3 having a hollow structure are put in a container 1 at a suitable ratio, the metal 2 is melted by the heating means 4, and then the kneading means 5 Particles 3 having a structure are dispersed in a melt of metal 2. While the molten metal 2 and the particles 3 having a hollow structure are kneaded, the molten metal 2 is solidified by the cooling means 6, thereby generating metal secondary particles 7 having a structure to which the hollow particles are attached. . Furthermore, after the secondary particles 7 and the metal 8 are put into a container 9 at a suitable ratio and the metal 8 is melted by the heating means 10, the secondary particles 7 are put into the melt of the metal 8 by the kneading means 11. Distributed. While the molten metal 8 and the secondary particles 7 are kneaded, the molten metal 8 is solidified by the cooling means 12, thereby generating a metal material 13 having a hollow structure with a circular or dendritic cross section.

The container 1 is not particularly limited as long as the shape can be stably maintained above the melting point of the metal 2 to be melted, but examples thereof include alumina, quartz, fluororesin, nickel, and a stainless steel crucible. The Further, the container 9 is not particularly limited as long as the shape can be stably maintained at the melting point of the metal 8 or higher, and the container 1 may be used.

The type of the metal 2 is not particularly limited as long as it is a material that changes in a molten state by a heating means, but in order to easily disperse by addition and kneading of the particles 4 having a hollow structure, A metal having a melting point of 800 ° C. or lower is preferable, and examples thereof include SnSbCu alloy, SnPb alloy, SnPbCd alloy, SnBiCd alloy, SnBi alloy, and more specifically, white metal (SnSbCu alloy) and U alloy (SnBi alloy). Further, the metal 8 is not particularly limited as long as it is a material that is changed into a molten state by a heating means, and the metal 2 may be used.

The particles 3 having the hollow structure are not particularly limited as long as the particles have a hollow structure and can maintain the particle shape until they are added to the molten metal 2. From the viewpoint of durability, the diameter of the particles 3 having a hollow structure is preferably 1 μm or more and 100 μm or less, more preferably 16 μm or more and 60 μm or less. Further, the total volume of the cavities included in the particles 3 having a hollow structure is preferably 50% or more, more preferably 76% or more with respect to the external volume. In addition, regarding the heat resistance temperature at which the particles 3 having a hollow structure can be maintained in shape, if fine bubbles can be dispersed in the melt of the metal 2, a hollow structure is formed in the molten metal, so that the particles dissolve instantaneously. Otherwise, there is no particular limitation, but it is preferable that the shape can be maintained in the metal 2 for 1 second or longer, and more preferably, the melting point of the particles is higher than the melting point of the metal 2. Specific examples of the particles having a hollow structure include hollow polymer microcapsules (Matsumoto Microsphere, Matsumoto Yushi Seiyaku), silica hollow particles (Glass Bubbles, 3M), and the like.

The ratio of the metal 2 to the container 1 and the particles 3 having a hollow structure is desirably 0.5% by weight or more, particularly preferably 1.5% or more, of the particles 3 having a hollow structure with respect to the metal 2. It is desirable to be. When the metal 2 and the particles 3 having a hollow structure are kneaded at a suitable ratio, and the metal 2 is solidified, the secondary particles 7 in which the particles 3 having the hollow structure are attached to the outside and the inside of the melt of the metal 2 are formed. To do. Further, the ratio of the secondary particles 7 and the metal 8 put in the container 9 is desirably 50 wt% or more of the metal 8 with respect to the secondary particles 7, particularly preferably 200 wt% or more and 800 wt% or less. It is desirable to be. When the secondary particles 7 and the metal 8 are kneaded at the preferred ratio and the metal 8 is solidified, a metal material 13 having a hollow structure having a circular or dendritic cross section as shown in FIGS.

The heating means 4 is not particularly limited as long as a known heating means capable of heating and melting the metal 2 to a melting point or higher is used. Preferably, an electric heating furnace, an oil bath, a hot plate stirrer, etc. are exemplified. The heating means 10 is not particularly limited as long as a known heating means capable of heating and melting the metal 8 to a melting point or higher is used, and the heating means 4 may be used.

The kneading means 5 is not particularly limited as long as the particles 3 having a hollow structure can be dispersed in the melt of the metal 2, but a kneading rod, a homogenizer, extrusion kneading, or the like may be used. Illustrated. In addition, when kneading, if the metal can be kept in a molten state, the use of the heating means 4 during kneading is not essential. Similarly, the kneading means 11 is not particularly limited as long as the secondary particles 7 can be dispersed in the metal 8 melt, and the kneading means 5 may be used. Moreover, use of the heating means 10 during kneading is not essential.

The cooling means 6 is not particularly limited as long as the molten metal 2 can be lowered to the melting point or lower. However, when rapidly cooling, cooling with water and cooling with a low-temperature incubator are exemplified. Further, when the metal 2 is solidified at room temperature and normal pressure, the cooling means 6 is not essential. The cooling means 12 is not particularly limited as long as the molten metal 8 can be lowered to the melting point or lower, and the cooling means 6 may be used. Further, when the metal 8 is solidified at normal temperature and normal pressure, the cooling means 12 is not essential.

EXAMPLES Hereinafter, although this invention is further demonstrated based on an Example, this invention is not limited to this.

White metal 80g, 1.2g silica hollow particles (Glassbubbles iM30K, 3M) with an average diameter of 16μm and a cavity of about 14μm inside are placed in an alumina crucible and heated sufficiently by an electric furnace set at 250 ° C. To a molten state. When a crucible containing molten white metal and silica hollow particles is kneaded with a stainless steel stirring rod at about 60 rpm, the molten white metal changes into a powder form wrapped with hollow particles. When the stirring bar is pulled out and allowed to stand at room temperature, the molten white metal is solidified to produce secondary particles having a diameter of 20 μm to 5 mm having a hollow structure on the surface and inside. Further, 81.2 g of the secondary particles are put into an alumina crucible, 160 g of white metal is added, and the mixture is sufficiently heated by an electric furnace set at 250 ° C. again. After the added white metal is in a molten state, the crucible containing the molten white metal and the secondary particles is kneaded with a stainless steel stirring rod at about 60 rpm until uniform. When the stirring bar is pulled out and allowed to stand at room temperature, the added white metal in the molten state is solidified to produce a metal having a hollow structure inside. Moreover, the porosity was 24% from the specific gravity measurement result of the metal which has the said hollow structure. The optical microscope image of the cross section of the metal produced | generated by the present Example 1 is shown in FIG. As shown in FIG. 2, annular or dendritic cavities were confirmed inside the metal, and it was confirmed that a metal having a hollow structure with a porosity of 24% derived from silica hollow particles and secondary particles was confirmed.

White metal 40g, 0.6g of silica hollow particles (Glassbubbles iM30K, 3M) with an average diameter of 16μm and a cavity of about 14μm inside are placed in an alumina crucible and heated sufficiently by an electric furnace set at 250 ° C. To a molten state. When a crucible containing molten white metal and silica hollow particles is kneaded with a stainless steel stirring rod at about 60 rpm, the molten white metal changes into a powder form wrapped with hollow particles. When the stirring bar is pulled out and allowed to stand at room temperature, the molten white metal is solidified to produce secondary particles having a diameter of 20 μm to 5 mm having a hollow structure on the surface and inside. Further, 40.6 g of the secondary particles are put in an alumina crucible, 160 g of white metal is added, and the mixture is sufficiently heated by an electric furnace set at 250 ° C. again. After the added white metal is in a molten state, the crucible containing the molten white metal and the secondary particles is kneaded with a stainless steel stirring rod at about 60 rpm until uniform. When the stirring bar is pulled out and allowed to stand at room temperature, the added white metal in the molten state is solidified to produce a metal having a hollow structure inside. The porosity was 18.1% based on the result of measuring the specific gravity of the metal having the hollow structure. The optical microscope image of the cross section of the metal produced | generated by the present Example 2 is shown in FIG. As shown in FIG. 3, annular or dendritic cavities could be confirmed inside the metal, and it was confirmed that a metal having a hollow structure with a porosity of 18.1% derived from silica hollow particles and secondary particles was confirmed.

20g of white metal, 0.3g of silica hollow particles (Glassbubbles iM30K, 3M) with an average diameter of 16μm and a cavity of about 14μm inside are placed in an alumina crucible and heated sufficiently by an electric furnace set at 250 ° C. To a molten state. When a crucible containing molten white metal and silica hollow particles is kneaded with a stainless steel stirring rod at about 60 rpm, the molten white metal changes into a powder form wrapped with hollow particles. When the stirring bar is pulled out and allowed to stand at room temperature, the molten white metal is solidified to produce secondary particles having a diameter of 20 μm to 5 mm having a hollow structure on the surface and inside. Further, 20.3 g of the secondary particles are put in an alumina crucible, 160 g of white metal is added, and the mixture is sufficiently heated by an electric furnace set to 250 ° C. again. After the added white metal is in a molten state, the crucible containing the molten white metal and the secondary particles is kneaded with a stainless steel stirring rod at about 60 rpm until uniform. When the stirring bar is pulled out and allowed to stand at room temperature, the added white metal in the molten state is solidified to produce a metal having a hollow structure inside. Moreover, the porosity was 10% from the specific gravity measurement result of the metal which has the said hollow structure. The optical microscope image of the cross section of the metal produced | generated by the present Example 3 is shown in FIG. As shown in FIG. 4, an annular or dendritic cavity was confirmed inside the metal, and it was confirmed that a metal having a hollow structure with a porosity of 10% derived from silica hollow particles and secondary particles was confirmed.

White metal 80g, 1.2g silica hollow particles (Glassbubbles K20, 3M) with an average diameter of 60μm and a cavity of about 58μm inside are placed in an alumina crucible and heated sufficiently by an electric furnace set at 250 ° C. To a molten state. When a crucible containing molten white metal and silica hollow particles is kneaded with a stainless steel stirring rod at about 60 rpm, the molten white metal changes into a powder form wrapped with hollow particles. When the stirring bar is pulled out and allowed to stand at room temperature, the molten white metal is solidified to produce secondary particles having a diameter of 20 μm to 5 mm having a hollow structure on the surface and inside. Further, 81.2 g of the secondary particles are put into an alumina crucible, 160 g of white metal is added, and the mixture is sufficiently heated by an electric furnace set at 250 ° C. again. After the added white metal is in a molten state, the crucible containing the molten white metal and the secondary particles is kneaded with a stainless steel stirring rod at about 60 rpm until uniform. When the stirring bar is pulled out and allowed to stand at room temperature, the added white metal in the molten state is solidified to produce a metal having a hollow structure inside. The porosity was 27.1% from the result of measuring the specific gravity of the metal having the hollow structure. The optical microscope image of the cross section of the metal produced | generated by the present Example 1 is shown in FIG. As shown in FIG. 5, annular or dendritic cavities were confirmed inside the metal, and the creation of a metal having a hollow structure with a porosity of 27.1% derived from silica hollow particles and secondary particles was confirmed.

White metal 40g, 0.6g silica hollow particles (Glassbubbles K20, 3M) with an average diameter of 60μm and a cavity of about 58μm inside are placed in an alumina crucible and heated sufficiently by an electric furnace set at 250 ° C. To a molten state. When a crucible containing molten white metal and silica hollow particles is kneaded with a stainless steel stirring rod at about 60 rpm, the molten white metal changes into a powder form wrapped with hollow particles. When the stirring bar is pulled out and allowed to stand at room temperature, the molten white metal is solidified to produce secondary particles having a diameter of 20 μm to 5 mm having a hollow structure on the surface and inside. Further, 40.6 g of the secondary particles are put in an alumina crucible, 160 g of white metal is added, and the mixture is sufficiently heated by an electric furnace set at 250 ° C. again. After the added white metal is in a molten state, the crucible containing the molten white metal and the secondary particles is kneaded with a stainless steel stirring rod at about 60 rpm until uniform. When the stirring bar is pulled out and allowed to stand at room temperature, the added white metal in the molten state is solidified to produce a metal having a hollow structure inside. Moreover, the porosity was 24.5% from the specific gravity measurement result of the metal having the hollow structure. The optical microscope image of the cross section of the metal produced | generated by the present Example 2 is shown in FIG. As shown in FIG. 6, annular or dendritic cavities could be confirmed inside the metal, and the creation of a metal having a hollow structure with a porosity of 24.5% derived from silica hollow particles and secondary particles was confirmed.

White metal 20g, average diameter 60μm, hollow silica particles (Glassbubbles K20, 3M) 0.3g inside with a cavity of about 58μm in diameter are placed in an alumina crucible and heated sufficiently by an electric furnace set at 250 ° C. To a molten state. When a crucible containing molten white metal and silica hollow particles is kneaded with a stainless steel stirring rod at about 60 rpm, the molten white metal changes into a powder form wrapped with hollow particles. When the stirring bar is pulled out and allowed to stand at room temperature, the molten white metal is solidified, and secondary particles having a diameter of 20 μm to 5 mm having a hollow structure on the surface and inside are formed. Further, 20.3 g of the secondary particles are put in an alumina crucible, 160 g of white metal is added, and the mixture is sufficiently heated by an electric furnace set to 250 ° C. again. After the added white metal is in a molten state, the crucible containing the molten white metal and the secondary particles is kneaded with a stainless stir bar at about 60 rpm until uniform. When the stirring bar is pulled out and allowed to stand at room temperature, the added molten white metal is solidified to produce a metal having a hollow structure inside. Moreover, the porosity was 14.6% from the specific gravity measurement result of the metal which has the said hollow structure. The optical microscope image of the cross section of the metal produced | generated by the present Example 3 is shown in FIG. As shown in FIG. 7, annular or dendritic cavities were confirmed inside the metal, and the creation of a metal having a hollow structure with a porosity of 14.6% derived from silica hollow particles and secondary particles was confirmed.

FIG. 8 shows the relationship between the porosity and the compressive yield stress of the white metal having a hollow structure and the white metal having no hollow structure prepared in Examples 1 to 6. As shown in FIG. 8, regardless of the size of the silica hollow particles to be kneaded, the yield stress decreases linearly with the increase in the porosity. Therefore, the strength of the metal having a hollow structure created by the proposed method is almost independent of the size of the hollow particles to be kneaded, and decreases in inverse proportion to the input amount. It is possible to control the strength of the metal having a hollow structure by changing the mixing ratio.

FIG. 9 shows the porosity of the white metal having a hollow structure created in Examples 1 to 6 and the sound transmittance in the 3 MHz to 30 MHz band when the white metal having no hollow structure is 1. The sound transmittance is 3MHz, which has a significant effect on the vibration power spectrum transmitted to the back surface when ultrasonic vibration is applied to the one surface in the laser ultrasonic test for the test piece of 5mm thickness. From the area ratio at 30 MHz. As shown in FIG. 9, in all of the examples according to the present method, the sound transmittance is 1/10 or less as compared with the case where there is no hollow structure, and has a remarkable vibration damping effect. I understand. In addition, the sound transmittance decreases linearly as the porosity increases, and the harmonic sound attenuation effect increases. Furthermore, a metal having a hollow structure made using 60 μm hollow particles has a higher damping effect than a metal having a hollow structure made using 16 μm and the same porosity, and hollow particles having an approximate straight line slope of 16 μm. Larger than the slope when used. Therefore, it is shown that the acoustic characteristics can be controlled by changing the size of the particles having the hollow structure while maintaining the same porosity and the same strength for the metal having the hollow structure created by the method of this application. It was done.

The metal material having a hollow structure obtained in the present invention is a light weight and high damping material, and the vibration absorption characteristic can be controlled by changing the hollow structure. Application is expected.

DESCRIPTION OF SYMBOLS 1 Container 2 Metal 3 Particles having a hollow structure 4 Heating means 5 Kneading means 6 Cooling means 7 Secondary particles 8 Metal 9 Container 10 Heating means 11 Kneading means 12 Cooling means 13 Metal material having a hollow structure

Claims (4)

A method for producing a metal material having a hollow structure, wherein metal particles having a hollow structure of 50% by weight or more with respect to a molten metal are dispersed and then cooled and solidified. The metal particles having a hollow structure according to claim 1 are formed by dispersing and solidifying a solid particle having a hollow structure of 0.5% by weight or more with respect to a molten metal. The method for producing a metal material according to claim 1. The solid particle having a hollow structure according to claim 2, wherein the external volume equivalent diameter is 1 μm to 100 μm in size, and the inside has a cavity of 50% or more with respect to the external volume. The manufacturing method of the metal material of Claim 2 The metal material which has the hollow structure manufactured by the method in any one of Claims 1-3.