Experiments on metallic foams under gravity and microgravity

Aluminium foams were created on ground and under microgravity conditions and were allowed to evolve. The entire foaming process was monitored by in situ X-ray radioscopy, allowing for flow and drainage of the liquid of the foam to be monitored and quantified. A foam with a known low stability level was used to enhance the effects of microgravity. The flow of metal out of the foam under gravity during the 1.8 g phase was found to be fast, indicating a mobile liquid. The density profile evolved in a similar way as in aqueous foams. Reentry of the liquid melt into the foam was also observed. Under microgravity the foam re-established a uniform density and pore size distribution after nearly complete imbibition of the liquid. This also shows that the liquid is mobile.