Surface Tension and Density of Indium–tin Melts and Their Dependence on Composition and Temperature

Abstract

The paper presents the results of measuring the surface tension (σ) and density (ρ) of indium-tin melts. The measurements of σ and ρ were carried out by different methods. The surface tension was measured by the sessile drop method and the maximum pressure in the droplet, while the density was measured by the areometer and sessile drop methods. High-purity metals In-00, tin – VHF were used for research. The maximum measurement error σ is 0.8%, and ρ is 0.2%. The dependence of σ of In–Sn melts on the composition is characterized by an extremum (flat minimum) in the region of equimolar composition. As the temperature increases, the depth of the minimum decreases, and its position shifts towards pure indium. Molar volumes have small positive deviations from additive values. As the temperature increases, the molar volumes approach additive values. The sessile drop method was used to measure the temperature dependences of σ and ρ of In–Sn solutions diluted with indium. It has been shown that indium additives lower the surface tension of tin. Given that the value of the surface tension of indium is higher than that of tin, this result indicates that the surface tension isotherms of the indium-tin system must pass through a minimum.