CaCO3 Blown Aluminium Foam and Equipment for Future Low Gravity Tests

Drainage of the liquid in metal foams causes inhomogeneous foam structure which decreases the quality of the product. The liquid flow is strongly influenced by the gravitational and capillary forces. Elimination of gravity could lead to a better understanding of the capillary forces and design less draining metal foams. We have developed an aluminium foam and an experimental device for imbibition experiment during parabolic flights. In this paper we describe the experimental device and show the results of the ground based tests. A new metal foam with strong drainage was prepared mixing 30 g pure aluminium with 30 g hot compacted (400 degrees C, 5 min, 300 MPa) aluminium powder (15 mu m particle size) at 700 degrees C followed by mixing of CaCO3 blowing agent. The precursor was cooled down in air and sliced to lg samples. We prepared the metal foam with drained melt on the bottom by simple reheating it to 800 degrees C. The foaming and the liquid motion in the foam was monitored on the ground by X-ray radioscopy. The oxidising blowing gas produced stable submillimetre sized bubbles which did not ruptured for several minutes. After the required expansion the foam cooled down and solidified. The ready foam was turned by 180 degrees or 90 degrees and remelted at 700 degrees C, at which expansion no longer occurred but the liquid motion could be monitored. The result showed detectable flow intensity during the time interval corresponds to several parabolas.