Process for producing shaped slabs of particle stabilized foamed metal

• US 5,334,236 A
• Filed: 06/29/1992
• Issued: 08/02/1994
• Est. Priority Date: 05/31/1991
• Status: Expired due to Term

• Current Assignee: Alcan Incorporated (Rio Tinto Limited)
• Original Assignee: Alcan Incorporated (Rio Tinto Limited)
• Inventors: Jin, Iljoon, Sang, Harry, Kenny, Lorne D.
• Primary Examiner(s): Andrews, Melvyn J.
• Application Number:
  US07/905,619
• Time in Patent Office: 764 Days
• Field of Search: 75/415, 427/244, 164/79
• US Class Current: 75/415
• CPC Class Codes: B22D 11/00 Continuous casting of metals, i.e. casting in indefinite lengths metal drawing, metal extruding B21C
• CPC Class Codes: B22D 11/06 into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
• CPC Class Codes: B22D 11/145 for upward casting
• CPC Class Codes: B22D 25/005 Casting metal foams
• CPC Class Codes: C22C 1/08 Alloys with open or closed pores
• CPC Class Codes: C22C 1/083 Foaming process in molten metal other than by powder metallurgy
• CPC Class Codes: C22C 1/086 Gas foaming process

Abstract

A process and apparatus are described for manufacturing particle stabilized foamed metal slabs. A foam is first formed in a foaming chamber by heating a composite of a metal matrix and finely divided solid stabilizer particles above the solidus temperature of the metal matrix and discharging gas bubbles into the molten metal composite below the surface thereof to thereby form a stabilized liquid foam on the surface of the molten metal composite. The stabilized liquid foam is continuously drawn off the surface of the molten metal composite and is solidified into a shaped foam product while being continuously drawn off.

Claims

1. A process for producing a slab of foam metal wherein the foam is formed by heating a composite of a metal matrix and finely divided solid stabilizer particles above the solidus temperature of the metal matrix and discharging gas bubbles into the molten metal composite below the surface thereof to thereby form a stabilized liquid foam on the surface of the molten metal composite,

characterized in that the stabilized liquid foam is continuously drawn off the surface of the molten metal composite and is continuously passed through a forming zone where it is formed into a foam product of desired cross-sectional shape.

2. A process according to claim 1 wherein the stabilized liquid foam is formed by moving it while being supported between a pair of moving belts.

3. A process according to claim 2 wherein the liquid foam is solidified while moving vertically upwardly between the belts.

4. A process according to claim 2 wherein the belts are endless belts.

5. A process according to claim 2 wherein at least one of said belts comprises a coil of sheet metal which bonds to a principal surface of the slab.

6. A process according to claim 3 wherein the belts are positioned with the bottom end of the gap therebetween engaging and drawing upwardly therebetween the liquid foam on the surface of the molten metal composite.

7. A process according to claim 1 wherein the liquid foam is solidified while moving horizontally or at an angle of no more than 45°

to the horizontal either on a single belt or between a pair of belts.

8. A process according to claim 1 wherein the stabilized liquid foam is formed into a desired shape by being drawn vertically through an orifice in the top of a chamber holding the molten metal composite and liquid foam.

9. A process according to claim 8 wherein the stabilized liquid foam is drawn upwardly by means of a chilled hook member placed within the liquid foam.

10. A process according to claim 8 wherein the stabilized liquid foam is drawn upwardly between rollers.

11. A process according to claim 9 wherein the rollers are profiled to shape the emerging foam product into a desired shape.

12. A process according to claim 8 wherein the orifice contains a central plug which forms the liquid foam into a hollow profile.

13. A process according to claim 1 wherein the metal is aluminum or an alloy thereof.

14. A process according to claim 8 wherein the particles have sizes in the range of about 0.1 to 100 μ

m and are selected from alumina, titanium diboride, zirconia, silicon carbide and silicon nitride.

15. A process according to claim 1 wherein the gas bubbles are formed by injecting a stream of gas below the surface of the molten metal composite and forming the gas bubbles by applying a shearing action to the gas stream.

16. A process according to claim 12 wherein the shearing action is provided by means of a rotating impeller.

17. A process according to claim 12 wherein the shearing action is provided feeding the gas through a reciprocating or vibrating injection nozzle.