Pressure infiltration of packed ceramic particulates by liquid metals

The work carried out on pressure infiltration of packed ceramic particulate by liquid metals, mainly aluminum and its alloys, is reviewed. The theoretical background and the main features of the technique and of the experimental procedures are first considered. The experimental results obtained by several authors approximately follow Darcy and capillary laws. The distinguishable roles of the key variables of the infiltration process are illustrated by means of selected experimental results. These variables can be classified according to their origin: (a) ceramic particulate (size and shape, surface condition); (b) liquid metal (surface tension, etc.); (c) liquid/solid interface (contact angle, reactivity, etc.); and (d) experimental variables (pressure, temperature, etc.). In particular, the importance of the particulate shape and size distribution, the surface tension of the liquid metal, the contact angle, and the oxide layer, in the case of aluminum, is highlighted. Results for binary aluminum alloys and alloys of technological interest (AlMgSi and AlCu alloys) are also discussed. Comparison of results for other metals with those for aluminum throws light on several aspects of the infiltration process. Of particular interest is silver, a metal having a behavior with respect to oxygen opposite to that of aluminum. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights Reserved.