Investigating Alumina-Silicate Bauxite and Phenol-Formaldehyde Resin Embedded TiH2 as Foaming Agents for Producing A356 Foam

Abstract

The melt foaming process has become the most widely used method in closed-cell aluminum foam manufacturing in large dimensions. This process creates pores by adding a foaming agent to the molten metal. Therefore, selecting appropriate foaming agents is vital, and it controls pore sizes and their distribution in producing a homogeneous foam. In the current research, as cost-effective foaming agents, the Bauxite and Phenol-formaldehyde resin (PFR) embedded TiH2 were successfully produced and then investigated by SEM and EDX analysis. It can be concluded that in the presence of the Bauxite ceramic phase and silica gel formation in Bauxite-embedded TiH2 and the formation of a carbon layer due to the burning of resin in PFR-embedded TiH2, heat-resistant protective layers are formed around TiH2 powders, and thus it delays (120 s) the gas release. The delay in the decomposition of H2 gas is equal to/higher than in the literature, and it gives the gas’ bubbles enough time to establish pores in the metallic matrix; thus, foams with uniform distribution of pores were produced. A quantitative examination of the cross-section of the produced foams shows that the number of cells with smaller sizes in the foams produced with the modified foaming agent is more, and the distribution of pores or cells is more homogeneous.