Aluminum Metallic Foams Made by Carbonate Foaming Agents

Abstract

Recent developments in metal foams, especially aluminum, have produced a new class of lightweight materials at the side of the traditional ones such as polymers, ceramics or glass. The combination of a metallic character together with a cellular structure gives an interesting potential for a wide application of this material, particularly for high volume markets such as the automotive industry. Increased demands concerning cost economy, passenger safety in automobiles and materials recycling all bring constructors now to use metal foams. Hereby it provides the additional environmental benefits from a potentially improved fuel economy and lower CO2 emissions. Then, short review of metallic foam was done in the present paper. The possibility of carbonate and hydroxide as foaming agent for Al-Si-Cu alloy by powder metallurgy route is studied, after preparation processes of metallic foams were briefly reviewed in the present paper. It was done by measuring thermal decomposition behavior of foaming agents and evaluating cell structure of those aluminum foams. To obtain fine and homogenous cell structure in powder metallurgy route by using safer carbonate as foaming agent, it has made clear that importance of selecting foaming agent starting decomposition after melting of matrix. It is clearly different from TiH2-foam to grow coarse-rounded cell structure. From this point of view, MgCO3 and CaMg(CO3)2 is suitable for matrix of Al-Si-Cu alloy. CaMg(CO3)2-foam could expand to 1.19 in specific gravity, and keep homogeneous, fine and spherical cell structure.