Research On Process And Properties Of Open Cell Aluminum Foams By The Space-holder Method

Aluminum foams have received a considerable amount of attention in recent years because of their extremely low density and unique functional properties such as impacting energy absorption, sound absorption, flame resistance and heat resistance. In most cases, the functions such as filtration, separation, heat or mass exchange, and sound or energy absorption require open-celled structures. Therefore, aluminum foams with open-celled structures have wider applications in functional structures. This paper describes a space-holder method for manufacturing open cell aluminum foams. The specimen preparing process consists of the mixing, compacting, removing of space-holder and sintering stages. The porosity, microstructure and compressive property of the foams were characterized.The results show that the spherical carbamide as a new space-holder can be used to produce aluminum foam samples with porosities between 50% and 80%. Depending on the shape distribution of the space-holder particles, the morphology of the pores in the foam can be easily controlled. It is also possible to obtain a purposely tailored distribution of pore size or relative density in the foam by using space-holder particles with different particle size ranges or by varying the weight fraction of the aluminum powders in the sintered compact. The ideal compaction pressure is 400MPa and the optimum sintering parameters are 550℃for 3 hours.All the foam samples of spherical shape pores show higher compressive strength comparing with these of strip shape pores or polygonal shape pores. The spherical carbamide particle is an ideal kind of space-holder for manufacturing open cell aluminum foams.The compressive strength of the aluminum foams increases with the porosity decreasing or the pore size increasing. The compressive strength is in agreement with the value predicted by theoretical models for open cell foams. The bending strength increases with a decrease in porosity. The energy absorption of the aluminum foams also increases with the porosity decreasing or the pore size increasing. The compressive strength of specimens range from 0.2MPa to 5.5MPa and the average energy absorption ratio is about 41.3%.