Title : Additive Manufacturing of Aluminum Porous Material with Closed Cell using Foaming Agent and Directed Energy Deposition
This paper focuses on the fabrication of a porous material manufactured using the direct energy deposition (DED) process, which is one of additive manufacturing technologies for metals. Materials with structures containing internal pores were manufactured by spraying a mixture consisting of AlSi2Mg powder and foaming agents onto an Al6061 substrate, and subsequently fused with the substrate using a high-power laser beam. The ensuing molten pool undergoes rapid solidification, resulting in the formation of a metal layer. Before the molten metal solidifies, the hydrogen gas generated from forming agents created pores inside the deposited layer. In this study, pored structures fabricated under various conditions were analyzed and compared from the viewpoint of compressive behavior. The results showed that the densities of the layered porous structures could be controlled by varying process parameters such as the laser power, scanning speed, and mix ratio of the foaming agent. The most dominant parameters to obtain a pored structure were the amount of foaming agent. The compression tests revealed that the porous materials manufactured using DED collapsed due to fracturing of the internal porous structures. After these structures fractured, the materials experienced densification, followed by crumbling. In addition, decreasing the laser power and scanning speed caused the compressive strength to decrease due to the high number of internal pores. Furthermore, before finally fracturing, the compressive strain decreased for specimens with increased porosity. The compression tests proved that the porous structure was able to effectively absorb compression loads.