Structural Characterization of Open-cell Aluminum Foams by a Sintering-Dissolution Process

摘要

This paper shows results in the preparation of net-shape open-cell aluminum foams by arnsintering-dissolution process (SDP). Al/NaCl compacts were prepared by cold uniaxial pressingrnof 70NaCl:30Al mixtures. Three different sizes of NaCl were employed, namely 600-850 μm,rn850-1410 μm and 1410-3350 μm. Compressibility tests showed that a maximum densificationrnwas reached when applying loads in the range 18-20 Ton; the green compacts were then sinteredrnunder argon at 645?C. After sintering, when the aluminum forms a well-bonded network, thernimbedded NaCl particles were dissolved in water, leaving behind an open cell Al foam. In thisrnway, Al foams with approximately 30 vol.% solids are obtained. The microstructure of the Alrnfoams, as a function of NaCl particle size, was statistically characterized in terms of therndescriptors pore size (Feret Diameter), pore shape (Shape Factor), and pore density by an imagernanalysis method. Even when the total porosity was practically the same in the three differentrnfoams, it was found that the pore size increased by increasing the size of the NaCl grains. Thernincreased pore size reduces the specific surface area of the porous structure, parameter thatrndetermines the interaction area between a fluid and the metallic wall in the foams.