Method for production of metal foam or metal-composite bodies

Abstract

A method for the production of foamable or foamed metal pellets, parts and panels. The method comprises the steps of: i) providing a mixture of a metal alloy powder with a foaming agent powder, ii) pre-compacting the mixture of step i); iii) heating the pre-compacted mixture of step ii) to a temperature below a decomposition temperature of the foaming and at which permanent bonding of the particles occurs v) hot compacting the body for producing a compacted body made of a metal matrix embedding the foaming agent; and vi) reducing the compacted body into metal fragments and thereby obtaining dense foamable metal chips. A method for the production of a foam metal using a closed volume metal shell is also disclosed. The method comprises the steps of: a) providing metal pieces and reducing said metal pieces into smaller metal particles; b) mixing the metal particles with an additive having a decomposition temperature that is greater than a solidus temperature of said metal particles; c) pouring the mixture of step b) into a closed volume metal shell having a given thickness and providing the metal shell with at least one passage for gases to escape; d) reducing the thickness of the metal shell by applying pressure; e) heating the metal shell to a temperature above said solidus temperature of the metal particles and below said decomposition temperature of the additive, and immediately applying pressure on the metal shell sufficient to compress the metal particles and to create micro shear conditions between the metal particles so as to obtain a dense metal product.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. Ser. No. 10 / 619,717 filed on Jul. 15, 2003, which is a continuation of International Patent Application No. PCT / CA02 / 00073 filed on Jan. 16, 2002, which designates the United States and claims priority Application Nos. U.S. 60 / 261,218 filed Jan. 16, 2001, CA 2,332,674 filed Jan. 29, 2001 and CA 2,344,088 filed Apr. 12, 2001. The above-mentioned applications are incorporated herein by reference in their entirety.FIELD OF THE INVENTION[0002]The present invention relates to the field of powder metallurgy. More specifically, it concerns a method of manufacturing foamable metal or metal-composite bodies and their use, particularly as lightweight and stiff material with improved impact, energy, sound absorption and heat retardant properties. It also preferably concerns environmentally friendly and low cost material produced from recycled aluminum alloys or scrap with broad range of chemical composition...

AI Technical Summary

Benefits of technology

[0040]e) heating the metal shell to a temperature above a temperature equal to said solidus temperature of the metal particles minus 55° C. more or less 5° C. (for example if the solidus temperature is 480° C., the metal shell will be heated at a temperature above 480° C. minus 55° C., that is to say above 425° C. more or less 5° C.) and below said decomposition temperature of the additive, and immediately applying pressure on the metal shell sufficient to compress the metal particles and to create micro shear conditions between the metal particles so as to obtain a dense metal product.

[0041]The metal pieces are preferably made of recycled aluminium scraps. Advantages of the process in such case are the following: its environmental friendliness since it uses recycled material, its cost effectiveness since the recycled aluminum scraps are readily available at low price. Another advantage is the fact that the chemical impurities contained in the aluminum metal scraps work as useful additives, which provide advantageous predetermined properties to the final product.

[0051]The method of the present invention can be used for production of porous metal bodies for the parts and structural elements used in civil-engineering, machinery, automotive and aircraft and other industries wherein combination of such unique properties of this material as high specific strength and rigidity, energy absorption, heat insulation and sound-proofing, light weight, incombustibility, buoyancy and absolute environmental acceptability are required.

Problems solved by technology

In addition, this method demonstrates a very low output because of the prolonged heating of the large size press container filled with the powder mixture.

Even in the case where the powder mixture would be heated in a container having 100 mm in diameter and 400 mm in height, the heating operation would be economically not feasible.

The disadvantages of these techniques are the limited possibility of production of semi-finished products, especially sheets of commercial sizes, low product yield and output, high manufacturing cost.

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