Analysis of Metal Foaming Behaviour and Development of Foaming Processes

摘要

The present paper highlights results from the priority program "Cellular Metals" of the Deutsche Forschungsgemeinschaft (DFG SPP 1075). Metal foams were made by foaming precursors containing a blowing agent. Two different manufacturing routes for precursors were analyzed and compared: hot-pressing of powders and thixocasting of cold-isostatically pressed powders. The foaming process was observed in-situ by X-ray imaging. Expansion kinetics, average pore sizes, drainage effects and pore morphologies were determined. The influence of gas atmosphere and overpressure on expansion and pore size was studied. Thixocasting parameters such as the pre-heating conditions of the slug, the cold-isostatic compaction pressure and TiH_2 content were optimized. Foam expansion and drainage of the optimized precursor were studied.