Wetting of Solid Molybdenum, Cobalt, and Nickel with Liquid Zinc and the Calculation of Their Interfacial Energies

The well-known experimental data on the angles of wetting of refractory metals with liquid zinc are used to calculate the interfacial energies in these systems. The calculation of this angle becomes a challenging problem, since there is no direct method for measuring the interfacial energy at the solid–another metal melt interface. Since the interfacial energies at the interfaces of solid metals with liquid zinc were calculated using the surface energies of solid metals measured by a noncontact method, i.e., in the absence of contact with a liquid metal, it is impossible to take into account the influence of a liquid phase on the surface energy of a solid metal. However, the influence of liquid zinc on the surface energies of solid metals may be ignored due to the fact that zinc does not form solutions and compounds with the metals under study. If the specific free surface energy is higher than the interfacial energy at the solid–melt interface, the equilibrium contact angle is acute; otherwise, i.e., at σss < σsl, the contact angle is obtuse. The closer the contact angle to the right angle at a contact angle higher than 90°, the higher the energy of adhesion of the liquid to the solid metal. However, the ratio of the adhesion energy to the surface energy of the melt remains smaller than unity. A further increase in the absolute value of the contact angle leads to a decrease in the adhesion energy to zero at 180°. Under equilibrium conditions in any systems, the contact angle is likely not to reach 180°. The results of calculating the interfacial energies of the systems under study demonstrate that the Young equation can be used to calculate the interfacial energy of the solid–liquid (melt) interface in the systems where chemical reactions do not occur, i.e., under equilibrium conditions. These results can be used to choose metallic melts for soldering the products made of refractory metals.