Method for manufacturing metal foam

Abstract

The present application provides a method for manufacturing a metal foam. The present application can provide a method for manufacturing a metal foam, which is capable of forming a metal foam comprising uniformly formed pores and having excellent mechanical properties as well as the desired porosity, and a metal foam having the above characteristics. In addition, the present application can provide a method capable of forming a metal foam in which the above-mentioned physical properties are ensured, while being in the form of a thin film or sheet, within a fast process time, and such a metal foam.

Claims

1. A method for manufacturing a metal foam, the method comprising: forming a green structure using a slurry; and sintering the green structure, wherein the slurry consists of a metal component, a dispersant, a binder, and optionally a solvent, wherein the metal component comprises a conductive metal with relative magnetic permeability of 90 or more or an alloy containing the conductive metal, wherein the sintering of the green structure is only performed by induction heating, and wherein the sintering of the green structure is performed by applying an electromagnetic field to the green structure for a time in a range of 1 minute to 10 hours.

2. The method for manufacturing a metal foam according to claim 1, wherein the conductive metal is any one selected from the group consisting of iron, nickel and cobalt.

3. The method for manufacturing a metal foam according to claim 1, wherein the metal component comprises 50 wt % or more of the conductive metal.

4. The method for manufacturing a metal foam according to claim 1, wherein the conductive metal has an average particle diameter in a range of 1 to 100 μm.

5. The method for manufacturing a metal foam according to claim 1, wherein the metal component is 10 to 70 wt % of the slurry.

6. The method for manufacturing a metal foam according to claim 1, wherein the dispersant is an alcohol.

7. The method for manufacturing a metal foam according to claim 1, wherein the binder is an alkyl cellulose, polyalkylene carbonate or polyvinyl alcohol compound.

8. The method for manufacturing a metal foam according to claim 1, wherein in the slurry, 5 to 500 parts by weight of the binder is present relative to 100 parts by weight of the metal component.

9. The method for manufacturing a metal foam according to claim 1, wherein in the slurry, 100 to 2,000 parts by weight of the dispersant is present relative to 100 parts by weight of the binder.

10. The method for manufacturing a metal foam according to claim 1, wherein the metal foam is in the form of a film or sheet.

11. The method for manufacturing a metal foam according to claim 10, wherein the film or sheet has a thickness of 2,000 μm or less.

12. The method for manufacturing a metal foam according to claim 1, wherein applying the electromagnetic field comprises applying a current in a range of 100 A to 1000 A.

13. The method for manufacturing a metal foam according to claim 1, wherein applying the electromagnetic field comprises applying a current having a frequency in a range of 100 kHz to 1,000 kHz.

14. The method for manufacturing a metal foam according to claim 1, wherein the electromagnetic field is applied for a time in a range of 30 minutes to 10 hours.

15. The method for manufacturing a metal foam according to claim 1, wherein the dispersant is ethylene glycol, propylene glycol, hexanol, texanol, or 1,6-hexanediol.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1 and 2 are SEM photographs of metal foams formed in Examples.

MODE FOR INVENTION

(2) Hereinafter, the present application will be described in detail by way of examples and comparative examples, but the scope of the present application is not limited to the following examples.

Example 1

(3) Nickel (Ni) having a conductivity of about 14.5 MS/m at 20° C., a relative magnetic permeability of about 600 and an average particle diameter of about 10 to 20 μm was used as a metal component. The nickel was mixed with a mixture in which ethylene glycol (EG) as a dispersant, ethyl cellulose (EC) as a binder and methylene chloride (MC) as a solvent were mixed in a weight ratio (EG:EC:MC) of 7:1:2, so that the weight ratio (Ni:EC) of the binder and the nickel was about 1:3, thereby preparing a slurry. The slurry was coated in the form of a film to form a green structure. Subsequently, the green structure was dried at a temperature of about 120° C. for about 60 minutes. An electromagnetic field was then applied to the green structure with a coil-type induction heater while purging with hydrogen/argon gas to form a reducing atmosphere. The electromagnetic field was formed by applying a current of about 350 A at a frequency of about 380 kHz, and the electromagnetic field was applied for about 3 minutes. After the application of the electromagnetic field, the sintered green structure was cleaned to produce a sheet having a thickness of about 20 μm in the form of a film. The produced sheet had a porosity of about 61% and a tensile strength of about 5.5 MPa. FIG. 1 is an SEM photograph of the sheet produced in Example 1.

Example 2

(4) A sheet having a thickness of about 15 μm was produced in the same manner as in Example 1, except that hexanol was used instead of ethylene glycol as the dispersant. The produced sheet had a porosity of about 52% and a tensile strength of about 6.7 MPa.

Example 3

(5) A sheet having a thickness of about 25 μm was produced in the same manner as in Example 1, except that 1,6-hexanediol was used instead of ethylene glycol as the dispersant. The produced sheet had a porosity of about 70% and a tensile strength of about 4.5 MPa.

Example 4

(6) A sheet having a thickness of about 30 μm was produced in the same manner as in Example 1, except that texanol was used instead of ethylene glycol as the dispersant. The produced sheet had a porosity of about 75% and a tensile strength of about 4.5 MPa.

Example 5

(7) A sheet having a thickness of about 30 μm was produced in the same manner as in Example 1, except that texanol was used instead of ethylene glycol as the dispersing agent, no solvent was used, and a slurry was used, which was prepared by mixing the nickel with a mixture in which the texanol and ethyl cellulose (EC) as the binder were mixed in a weight ratio (texanol:EC) of about 9:1, so that the weight ratio (Ni:EC) of the binder and the nickel was about 1:3. The produced sheet had a porosity of about 77% and a tensile strength of about 4.2 MPa. FIG. 2 is an SEM photograph of the sheet produced in Example 5.

Example 6

(8) A sheet having a thickness of about 30 μm was produced in the same manner as in Example 1, except that propylene glycol was used instead of ethylene glycol as the dispersant.

Comparative Example 1

(9) A sheet was produced in the same manner as in Example 1, except that no dispersant was used, and a slurry was used, which was prepared by mixing the nickel with a mixture in which ethyl cellulose (EC) as the binder and methylene chloride (MC) as the solvent were mixed in a weight ratio (EC:MC) of 15:85, so that the weight ratio (Ni:EC) of the binder and the nickel was about 1:3. The produced sheet was very brittle and easily broken, and thus the tensile strength could not be measured.