Refoaming of deformed aluminum foam by precursor foaming process

Aluminum (Al) foam does not recover to its initial shape once it absorbs shock energy and deforms. In this study, the refoaming of deformed A6061 Al foam was attempted. Closed-cell Al foam fabricated by a precursor foaming process was reproduced to obtain a similar closed-cell Al foam by subjecting it to the precursor foaming process again. It was found that only slight refoaming of the precursor was observed for a cold-compressed Al foam. It is considered that the low density of the precursor causes the release of the generated gases from the cracks and pores of the precursor. In contrast, sufficient refoaming of a cold-compressed precursor can be achieved by conducting spark plasma sintering (SPS). Initial Al foams with porosity of approximately 80% and closed-cell pore structures can be reproduced with similar porosity and pore structures. From these results, it was found that not all the blowing agent in the precursor was used during the initial foaming, and some of the blowing agent remained in the foamed Al foam without decomposition. Therefore, the successful reproduction of the Al foam was due to the remaining blowing agent in the initial Al foam.