Kinetics of liquid penetration into bottom edge of cast tape

Thin tapes are frequently used in modern applications to be filled with liquid into the void spaces among compacted particles. Then, the enhancement of liquid penetration into the particle layer offers the great promise to the industry in terms of improving their performance and increasing the production rate of devices utilizing such tapes. In the present study. the liquid penetration rate is measured for green and pressed tapes prepared under various cast parameters with graphite particles differing in original particle properties. In addition, an attempt is made to derive the penetration rate from the tape characteristics of porous microstructure. The mathematical model of liquid penetration kinetics was developed, assuming the tape void space as the bundle of capillaries. The distribution of capillary diameters was defined as the distribution of void sizes measured by image analysis on the cross-section perpendicular to the tape surface. As a result, it was confirmed that the measured rate of liquid penetration into the tapes, which were prepared with various casting speeds, blade gaps and slurry concentrations, is mainly determined by the distribution of void sizes. The largest value of the penetration rate constant was obtained for the tape made of spherical particles followed by those manufactured with fibrous, blocky and flaky particles, as Could be expected from the analysis of void size distributions. Penetration rates into layers of synthetic graphite particles were higher than in those made of natural particles possibly due to the difference in their contact angles. (C) 2004 Elsevier B.V. All rights reserved.