Stability of close-cell Al foams depending on the usage of different foaming agents

Abstract

Close-cell Al foams produced by the powder-metallurgy (PM) route can be made with different foaming agents, regarding the type of liberated gas. Most commonly, H2 gas is used as the liberation agent, but there is a huge improvement made with CO2 gas liberating agents, such as calcite and dolomite. In order to determine the benefits and/or disadvantages of foaming agents, studies of the foam pores' stability, depending on the type of liberated gas, were performed. The stability of Al foams was studied by different analytical techniques, i.e., AES, expandometer, heating microscopy and SEM/EDS. AlSi12 aluminium powder as the matrix material and TiH2 and CaCO3 as the foaming agents liberating different gases - one based on H2 and another on CO2 - were used. Based on the obtained results, the mechanism of foam stability was studied and a comparison of the two foaming agents was made and evaluated.