Reducing Threshold Pressure for Infiltration of Al-12Si Alloys into Carbon Particle Compacts by Placing a Thin Layer of Sn at the Infiltration Front
The oxide layer that usually covers the surface of liquid aluminum and its alloys, is one of the main factors that hinders infiltration of these alloys into graphite particle compacts. The oxide film increases the threshold pressure for infiltration and the porosity of the resulting composites is large because the wetting at the metal/carbon interface is reduced. Infiltrating graphite compacts with tin requires, however, a much lower pressure, less than half of that required to infiltrate the eutectic Al-12Si alloy. As the surface tension of tin is half that of the Al-12Si alloy, this result indicates that wetting at the Sn/C interface is slightly better. As a result, porosity in the infiltrated samples is reduced. In order to reduce the threshold pressure and improve the properties of Al-Si/graphite composites, a novel method has been used in this work that consists in placing a thin film of tin at the compact end through which infiltration takes place. During the infiltration process the graphite particles are firstly infiltrated by tin, which is pushed by the aluminum alloy, thus avoiding the oxidation of the latter. The method proved to be very effective in reducing the threshold pressure, while keeping almost constant the infiltration rate.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
A. Rodríguez-Guerrero et al., "Reducing Threshold Pressure for Infiltration of Al-12Si Alloys into Carbon Particle Compacts by Placing a Thin Layer of Sn at the Infiltration Front", Materials Science Forum, Vols. 539-543, pp. 785-790, 2007