X-ray radioscopy of liquid metalfoams: influence of heating profile, atmosphere and pressure

Metal foams are investigated in situ and in real time with help of X-ray radioscopy. The equipment consists mainly of three parts: (1) a microfocus X-ray source, (2) a panel detector and (3) a small foaming heater, almost transparent for X-rays. For these works a novel X-ray transparent pressure heating systems for foaming under controlled atmosphere was developed and constructed. The control of the foaming temperature profile was found to be a determining factor for expansion and stability of metal foams. Moreover, other parameters such as foaming gas and foaming ambient pressure were also tested. Different expansion and stability behaviour on metallic foams was achieved using different temperature profiles. Expansion and average cell size also could be controlled adjusting the ambient foaming pressure. By foaming under high pressures low average pore diameters could be reached. Foam behaviour under cyclical pressure variation was elastic and reversible in a certain range.