Preparation Of Aluminum Foam And Its Compressive Properties Research

Aluminum foam can combine various excellent properties, such as low density, high strength, low thermal conductivity, low permeability and good damping properties, which can play important roles both in the field of structural materials and functional materials and bring broad application prospects. This paper aims at the preparation of aluminum foam by melt foaming process. Optimized process parameters were obtained through the experiments and the compressive performance was investigated.In this study, raw material was pure aluminum; thickening agent was Ca; TiH2 acted as blowing agent with pre-heating treatment for 2 hours at 300℃prior to processing. A few amount of Mg was added into the melt to control the thickness of the bubble-free layer of aluminum foam. Based on the above research work, aluminum foam with preferable structure was obtained.Orthogonal experiment was designed; the porosity and the pore uniformity act as the indexes during the analysis process. The relationship between the cell structures and the processing parameters such as thickening agent amount, foaming agent amount, foaming temperature, stirring time and foaming time was studied. The result shows that the thickening agent amount and foaming time are the main factors for the cell structure. So controlling the melt viscosity is the pivotal process in the Al foam preparation.The optimized processing parameters to manufacture aluminum foam by melt foaming technology with our experiment condition are:Adding 3.5%Ca and 0.5%Mg to Al melt at 730℃; Stirring for 10min at the speed of 800r/min to improve the viscosity; 0.3%TiH2 with pre-heating treatment for 2 hours at 300℃was added into the melt, following with stirring for 40s at the speed of 1 OOOr/min to disperse the blowing agent; Cooling in the air after foaming for 30s with the furnace. Then uniform aluminum foam with porosity 70%-80% was obtained.The compressive properties of the aluminum foam were investigated, and stress-strain curves with three-stage deformation were showed. The porosities have great influence on their compressibility and energy absorption. The drape on the cell wall can hasten the formation and expansion of the flaw. The aluminum foam failed through a mixture of ductile tearing and brittle fracture. The crack grows along the grain boundary.