Improvements in stabilisation and cellular structure of Al based foams with novel carbonate foaming agent

Abstract

In the present paper the applicability of CaCO3 foaming agent for making Al-based foams by Alporas route as well as by powder compact technique is studied. Its effect on the foaming behaviour of the melt or powder precursor, stabilisation of liquid foam with solid particles, layers or network of thin oxide films as well as on the cell size and cell wall microstructure of final solid foam is clarified and discussed in comparison with conventional TiH2 foaming agent. It is underlined that application of the novel foaming agent is more favourable in view of the processing conditions because of remarkable improvement in foam stabilisation by melt oxidation. In addition, advantages in application of CaCO3 as foaming agent for clearing the cell wall material from undesirable contaminations induced typically by conventional titanium hydride TiH2 is justified.