Solid surface energy measured electrically

A new method is described for determining the surface energy of conducting powders. The technique depends on the relation between surface energy and contact diameter of two smooth elastic spheres touching under zero external load. Since electrical conductivity through the contact is also a function of contact diameter, an equation relating conductivity and surface energy may be derived. By making some assumptions about the geometry of a bed of powder, this equation can be generalised to describe the behaviour of a mass of powder. Experiments on powder compacts made from carbon black support this hypothesis.