Fabrication of high-porosity open-cell aluminum foam via high-temperature deformation of CaCl2 space-holders

Abstract

In this study, we found that porous CaCl2 granules can be easily deformed under certain pressure and temperature conditions. Based on this finding, a new infiltration process that employs CaCl2 granules as space-holders was developed to prepare aluminum (Al) foam with high porosity. In this process, porous CaCl2 granule preforms were first subjected to hot-pressing deformation, which provided two benefits: 1) the density of the preform was increased, thereby increasing the porosity of the final prepared open-cell Al foam (over 80%) and 2) the contact surface of the neighboring CaCl2 granules was increased. After hot-pressing, the sizes of the dissolution and removal channels of CaCl2 increased. Consequently, the space-holder particles could be completely removed, which is just the most difficult bottleneck problem in the traditional infiltration process applying salt particles as space-holders in which the salt removal is not enough and the porosity is lower than 65%.