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 comprising: sintering a green structure, wherein the green structure consists of a metal component and a salt, and optionally a binder and/or solvent, wherein the metal component comprises a conductive metal in an amount of 55% by weight or more, wherein the metal component is in a form of a powder, and wherein the sintering of the green structure consists of applying an electromagnetic field to said structure so as to generate heat from the conductive metal in the metal component, wherein the green structure is in a form of a film or a sheet having a thickness of 1,000 μm or less, wherein the conductive metal is nickel, iron or cobalt, wherein the conductive metal has an average particle diameter in a range of 10 μm to 100 μm, wherein the salt is NaCl, KCl, K.sub.2CO.sub.3, KOH, NaOH, CsCl, CaCl.sub.2, MgBr.sub.2, MgCl.sub.2, Na.sub.2SiO.sub.3, Na.sub.2CO.sub.3, NaHCO.sub.3, NH.sub.4Br or NH.sub.4Cl, wherein the salt has a particle diameter in a range of 30 μm to 250 μm, wherein the electromagnetic field is formed by applying a current at a frequency in a range of 100 kHz to 1,000 kHz, and wherein the green structure is formed by coating a mixture of the metal component and the salt on a substrate.

2. The method for manufacturing a metal foam according to claim 1, wherein the conductive metal has a conductivity at 20° C. of 8 MS/m or more.

3. The method for manufacturing a metal foam according to claim 1, wherein the green structure comprises, on the basis of weight, 30% by weight or more of the conductive metal.

4. The method for manufacturing a metal foam according to claim 1, wherein the green structure comprises 10 to 1,000 parts by weight of the salt, relative to 100 parts by weight of the metal component.

5. The method for manufacturing a metal foam according to claim 1, wherein the electromagnetic field is formed by applying a current in a range of 100 A to 1,000 A.

6. The method for manufacturing a metal foam according to claim 1, wherein the electromagnetic field is formed by applying a current at a frequency in a range of 100 kHz to 900 kHz.

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

8. The method for manufacturing a metal foam according to claim 1, further comprising removing the salt after sintering.

9. The method of claim 1, further comprising forming the metal foam having uniformly formed pores.

10. The method of claim 9, wherein the metal foam has a porosity in a range of about 40% to 99%.

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) A powder of nickel metal, which is the conductive magnetic metal, was used as a metal component. The nickel metal powder sieved through a 200-mesh sieve was mixed with NaCl as a salt in a weight ratio of 1:1. Here, as the NaCl, those having a particle diameter distribution within a range of about 50 μm to 100 μm were used. On the other hand, in the above nickel, the conductivity at 20° C. is about 14.5 MS/m and the relative magnetic permeability is about 600 or so.

(4) The prepared mixture was coated on a quartz plate in the form of a sheet having a thickness of about 600 μm to produce a green structure, and an electromagnetic field was applied to the green structure with a coil-type induction heater. 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 application of the electromagnetic field, the sintered green structure was immersed in water and washed with sonication to remove the salt, thereby manufacturing a sheet form of metal foam having a thickness in a level of about 600 μm. The manufactured sheet had a porosity of about 53%. FIG. 1 is a SEM photograph of the manufactured sheet.

Example 2

(5) A metal foam was manufactured in the same manner as in Example 1, except that the weight ratio of the nickel metal powder and NaCl was changed to 1:1.5 (nickel metal powder: NaCl). The manufactured sheet had a porosity of about 70% or so. FIG. 2 is a SEM photograph of the manufactured sheet.

Example 3

(6) A metal foam sheet was manufactured in the same manner as in Example 1, except that Na.sub.2SiO.sub.3 having a particle diameter distribution in a range of about 50 μm to 70 μm was applied as a salt. The manufactured sheet had a porosity of about 55%.

Example 4

(7) A metal foam sheet was manufactured in the same manner as in Example 1, except that Na.sub.2CO.sub.3 having a particle diameter distribution in a range of about 150 μm to 200 μm was applied as a salt. The manufactured sheet had a porosity of about 43%.

Example 5

(8) A metal foam sheet was manufactured in the same manner as in Example 1, except that KCl having a particle diameter distribution in a range of about 70 μm to 100 μm was applied as a salt. The manufactured sheet had a porosity of about 62%.

Example 6

(9) A metal foam sheet was manufactured in the same manner as in Example 1, except that NH.sub.4Cl having a particle diameter distribution in a range of about 25 μm to 55 μm was applied as a salt. The manufactured sheet had a porosity of about 58%.

Example 7

(10) A metal foam sheet was manufactured in the same manner as in Example 1, except that CaCl.sub.2 having a particle diameter distribution in a range of about 70 μm to 110 μm was applied as a salt. The manufactured sheet had a porosity of about 60%.

Example 8

(11) A metal foam sheet was manufactured in the same manner as in Example 1, except that MgCl.sub.2 having a particle diameter distribution in a range of about 50 μm to 70 μm was applied as a salt. The manufactured sheet had a porosity of about 42%.