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The aim of our experimental work was to establish a simple relation between the flow parameters and the morphological parameters of metallic foam. We used foam samples made from different metals or alloys (Cu, Ni, Ni-Cr, etc) and of various thicknesses. Pore size ranged between 500 and 5000 µm. We measured the pressure profiles in foam samples using a specific experimental set-up of 12 pressure sensors distributed 1 cm apart along the main flow axis. The experimental loop made it possible to use indifferently water or air as working fluid. For the study of the gas (air) flow, velocities ranged roughly from 0 up to 20 m/s and for the liquid (water) flow, velocities ranged between 0 and 0.1 m/s. The measurements of the pressure gradients were performed systematically. We validated the Forchheimer flow model. The influence of the compressibility effects on permeability and inertia coefficient was emphasized. We demonstrated that the pore size Dp in itself is sufficient to describe flow laws in such high porosity material: K and β are respectively proportional to Dp 2 and Dp −1 .

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International audienceThe interactions between zirconia (ZrO2) powder and three Algerian hydrated kaolinitic clays were studied at high temperatures. The analysis by X-ray diffraction of the prepared products allowed to follow the different phase developments during heat treatment and to identify the parameters controlling the zirconia conversion into zircon (ZrSiO4). It was found that ZrSiO4 formation, occurring at temperatures above 1150°C, is enhanced by the presence, in the clays, of fusing impurities such as K, Fe, Ca, and Mn, and by a decrease in zirconia particle size. A reactional mechanism, involving zirconia, a flux, and cristobalite is proposed. Moreover, the effect of zirconia additions on sintering was studied. It was also found that the increase in the porosity ratio of the final products for zirconia levels above 20 wt% was governed by a decrease in the flux amount, due to its lower clay content. Finally, it was shown that ceramics obtained by sintering at 1400°C for 2 h of a mixture of 38 wt% of fine zirconia powder and 62 wt% of the more reactive clay were mainly constituted of zircon and mullite