Assessment of TiH2 and CaCO3 Blowing Agents on Structure and Properties of the Al-7%Si-3%SiC Composite Metal Foam

In this paper, the effect of TiH2 and CaCO3 blowing agents was investigated on the structure and energy absorption of Al-7%Si-3%SiC composite metal foam by powder compact route. Composition of the foam was prepared from a mixture of Al,SiC and Si powders. Then, precursors were consolidated in H13 die mould by cold and uni-axial pressing at 110 MPa and at room temperature. The pressed precursors were extruded at 500oC, in a 12*24 mm2 cross-section. Then, the precursors were foamed in a 316L-stainless steel tube with diameter and height of 20 mm and 100 mm, respectively, in an electrical resistance furnace. Finally, for micro-structural investigation the samples were cut and polished, and a scanning electron microscope was used to observe the cell wall and surface topology. For calculation and comparison, energy absorption was used in an Instron Hydraulic test machine and the foam samples were compressed at the ramp velocity of 50 mm/minute. Results showed that foams with CaCO3 agent due to having high porosities are more stable than foams with TiH2 agent. Also, the energy absorption for foam with CaCO3 agent is more than foams with TiH2 agents. However, its drainage due to less thickness of wall porosities is better than the foam with CaCO3 agent.