1993 Volume 19 Issue 6 Pages 1136-1142
The stable separation distance between two spherical particles adhering by a liquid bridge is theoretically analyzed. The result shows that, as the separation between the two particles becomes smaller, the adhesion force increases and at the same time the surface free energy of the liquid bridge decreases. As a result, the two particles come into contact unless external forces are exerted.
The relation between separation distance and adhesion force was observed using a pair of two glass spheres or two convex lenses where water bridges are formed. The result was found to be in good agreement with the theoretical analysis. Another observation supported the analysis, where two dry glass spheres separately hung to keep a certain horizontal separation between them came into contact when a bridge was formed by a drop of water between the spheres.
The fact that the bulk volume of a powder bed decreases with increase of moisture content also supports the present analysis.
