Preparation of Aluminum Foam with Uniform Distribution of Small Pore Sizes by a Novel Composite Foaming Agent

Metals foamed, especiallyaluminum foam, are increasingly widely used in the materials field. The melt foaming process has been widely used in industrial production due to its high preparation efficiency and relatively stable product properties. Although the exact interrelationship between properties and pore structure is not yet fully understood, uNiformly distributed foams with small pore sizes and fewer defects are always highly desirable.

Currently, the pore size and structure of aluminum foams are difficult to control during the melt foaming process, and it is challenging to fabricate aluminum foams with small pore sizes, mainly due to the early decomposition and poor dispersion of the blowing agent (usually TiH2). Based on this, the group of Prof. Yanxiang Li at Tsinghua University studied the process of pre-dispersion of TiH2 in the melt of AlMg35 intermediate alloy after oxidation treatment, which can complete the dispersion process without decomposition, and created a new AlMg35-TiH2 composite foaming agent. The effects of stirring time and blowing agent dosage on the quality of the corresponding aluminum foam were also analyzed. The research results were published in the journal "Journal of Materials Processing Technology" with the title "Development of AlMg35-TiH2 composite foaming agent and fabrication of small pore size aluminum foams". Journal of Materials Processing Technology. Aluminum foams prepared with this composite foaming agent are characterized by good structure, small pore size, uniform pore distribution and spherical pore shape. The improvement of this process is that the TiH2 particles are dispersed into the low melting point alloy melt by longer stirring time and are not easy to decompose.

The blowing agent succeeded in preparing excellent and reproducible cellular structures of small pores in aluminum foams with a reduced average pore size of 0.6 mm, which was mainly attributed to the delayed decomposition time of TiH2 due to the pre-oxidation treatment and AlMg35 embedded in it, which made the stirring time more tolerable. The pre-oxidized TiH2 particles were dispersed in the liquid AlMg35 alloy, making it easier to disperse the TiH2 particles in the aluminum melt with less particle aggregation. In addition, the method reduces the amount of TiH2 added at the foaming stage, which is less costly and more suitable for industrial manufacturing.