Aluminum Foam With Small Pore Diameter Preparation And The Mechanism Of Pore Diameter Reducing

Aluminum foam is a composite material which is consisted metallic matrix and gas bubbles. It has an extensive application in many different areas. Tremendous research activities about aluminum foam have been implemented. Preparation and mechanics of pore diameter reducing and Compressive property was researched in this paper.Aluminum foam with fine cell structure was made successfully by melt foaming in this paper. The average cell diameter of aluminum foam is about 1.3 millimeter, The porosity is 70.5%. The cell structures are distributing uniformly. The optimal processing parameters is:melting temperature of aluminum 685℃; content of Calcium 1.5%; content of Magnesium 0.5%; stirring time 5min; content of foaming agent 0.3%; foaming agent being treated on 400℃6h and 500℃1h; foaming time 60s; stirring speed 3000rpm; time of heat insulation 1.5min.Preparation mechanism of Al foam with fine cell structure was researched in the paper. The result illustrated that:(1) Bubble stabilization has close relationship with melt viscosity and surface tension. When melt viscosity increased and surface tension decreased, bubble stabilization will be improved. (2) When melt viscosity increased and stirring speed slowed, dispersion of foaming agent will be lower. The stirring time could not very long(<70s), becouse of the available dispersion time of TiH2. The aggregation of foaming agent can be improved and aluminum foam with fine cell structure can be preparation by changing the condition of processing. (3) Oxidizing of foaming agent could delay the starting decomposition time and slow the decomposition rate. When the temperature of oxidizing of foaming agent increased from 450℃to 520℃, the effect of slower the decomposition rate will enhanced. However, the volume of decomposition foaming agent will reduced from 185ml to 125ml. When the temperature of oxidizing of foaming agent and stirring time matched, aluminum foam with fine cell structure will be maded. (4) Solid-phase particles in the aluminum melt could act as the nuclei during heterogeneous nucleation.Compressions of Al foam with fine cell structure was researched in the paper. Yield strength of aluminum foam (porosity between 63.5%-76%) is 5.2 MPa to 14.8 MPa and energy absorption capability is 5.2 MJ/m3 to 11.5 MJ/m3. Yield strength and energy absorption will be improved with cell diameter reducing.