Pore Morphology of Lotus-type Porous Silver Fabricated by Gasar Process in Oxygen Atmosphere

Directional solidification of metal/gas eutectic (Gasar) is a novel process for fabricating porous metals with oriented pores parallel to the solidification direction. Lotus-type porous silver samples with different porosities were fabricated by Gasar apparatus under pure oxygen atmosphere. The effects of gas pressure on porosity, pore nucleation, pore size and distribution were investigated. Results show that the porosity and the pore size in the lotus-type porous silver are significantly affected by the oxygen pressure. The porosity increases with the increasing of oxygen pressure, and the average pore diameter decreases with the increasing of oxygen pressure.