Capillary forces in a low gravity environment

The capillary properties of a liquid (silicone oil) attached to a large circular solid surface (titanium) and held in the form of an axisymmetric liquid zone by a second smaller solid disk were studied on Spacelab. The unperturbed shapes and stability properties of these (zero-g) axisymmetric zones were obtained from the Laplace capillary equation. The principle by which a Laplace shape may be distorted by external force fields is described and the features of the method by which solid-liquid disjoining pressure is measured, are given. Experimental methods, image recording, image processing and the antispread treatment are described. It is found that the antispread works nominally and that the electrical field shows no effects. Equilibrium is reached very quickly and zone breakage was recorded. Thirteen data points were obtained with capillary pressures in the range -0.4 to -0.009 N/sqcm. At the lower pressure, very thick liquid films form; at higher pressures the films are thin.