---

The unique properties of metal foams, including light weight, energy absorption, low thermal conductivity and recyclability, have led researchers to explore new ways to achieve these materials with a good relationship between properties and production costs. Different production methods are divided into two groups of liquid state and powder method based on the initial state of the metal. The aim of this study is to provide a new method for the production of open cell aluminum foam with Sodium Chloride spacer. Two different types of aluminum alloy with different fluidity were used to produce foam with this method. Pressure tests were performed to show the compressive behavior of aluminum foams. The results showed that the behavior of foams produced by this method is the same as the outcomes of other papers. In different densities, the behavior of the soft foam was the same, but the stress was higher in the same displacement for higher densities. In the same density for the two different alloys, the axial strength of the A332 alloy was higher, but in contrast the soft foam is a good energy absorber. Young's modulus for two types of alloys with identical densities was 1.45 GPa for the A332 alloy and 1.11 GPa for the 1067 alloy. The amount of energy efficiency decreased by densifying the foam.

---

Slurry casting method is a novel process to produce metal forms, which makes it possible to produce a porous structure with open cell. In the present study, the microstructure and compressive behavior of aluminum foams produced by slurry casting method, under different number of immersion times were investigated. For the production of aluminum foams with different cell sizes, polyurethane preforms with characteristics of 45, 55 and 65 ppi were selected, and after immersing in a slurry having a solid mass of 88% and removing the excess semiliquid mixture, the samples were sintered at 630˚C. The size of polyurethane perform cell as well as the number of immersion times control the microstructure and compression performance of porous structures. The results of the study showed that the portability of porous aluminum increases by decreasing the size of preform cell or increasing the number of immersion times, which leads to thicker strut. In addition, the probability of crack existence, exactly at the corner of structures, decrease via enhancing the thickness of strut. Meanwhile, excessive increase in the number of immersion, i.e. third times, was associated with some closed-cells which results in strain localization and stress concentration. Therefore, the maximum plateau stress as well as the superior energy absorption capacity was observed in the sample having the minimum preform pore sizes which was immersed for two times in the aluminum slurry.