Mr Hojjatollah Fathi, Dr Esmaeil Emadoddin, Dr Ali Habibolah Zadeh,
Volume 9, Issue 3 (9-2012)
Abstract
Metal porous foams have been eliciting much interest in recent years due to their high capacity of energy absorption. The characteristics of the pores in these materials play an important role on their energy absorption capability and other properties. This study reports the fabrication of aluminum closed-cell foams by accumulative roll-bonding (ARB) technique using calcium carbonate (CaCO3) as the blowing agent. Calcium carbonate is an inexpensive material and imparts relatively high porosity to the produced foam. The effects of heating rate foaming temperature and time on porosity have been investigated. The results show that increasing the foaming temperature and time results in improvements in the foaming process. It is also shown that the heating rate does not affect the porosity. The shape and structure of pores are spherical and regular with CaCO3 as blowing agent. With TiH2 blowing agent the sample should be heated up abruptly from decomposition temperature of TiH2 to foaming temperatures in order to produce high porosity foam. It is found that increasing the numbers of accumulative rolling cycle causes uniform distribution of calcium carbonate powder and increases porosity in the final foam by up to 55%.
H. Azimi,
Volume 17, Issue 2 (6-2020)
Abstract
In this work, the poly styrene-co-acrylonitrile (SAN)beads and three blowing agents (CO2, N2 and n-pentane) were used to investigate the foaming process via our batch foaming system. The solubility and diffusivity of three blowing agents were determined by the MSB. The solubility of blowing agents was increased by pressure and decreased by temperature increment. It was resulted that the solubility and diffusivity data for SAN/n-pentane/CO2 system (Using co-blowing gent) were higher than other samples. According to the scanning electron microscopy (SEM) results, it was concluded that the cell and foam densities were decreased with temperature increment and increased by pressure release rate in all foamed beads. With using co blowing agents, higher pressure release rate and low temperature without adding any fillers, we could improve the foam characteristics and produced the SAN foams with smaller cell sizes and greater cell and foam densities.
