Drop size dependence of contact angles for liquid tin on silica surface: line tension and its correlation with solid–liquid interfacial tension

Abstract

Using the sandwich drop method, advancing contact angles were measured for liquid tin on the silica (SiO 2) surface under high vacuum (10 −5 Pa) at 1173 K. A drop size dependence for the measured contact angles was observed, i.e. the contact angle decreased as the drop's base radius was increased. In line with explaining similar observations for “low-energy” (i.e. organic) systems, the observed trend for the Sn–SiO 2 (i.e. “high-energy”) system was interpreted using the modified Young equation. It was found that the drop size dependence of contact angles can be interpreted as being due to a positive line tension. The line tension value obtained might seem to be large (155 μJ/m) in comparison with the line tension values of the order of 1 μJ/m for low-energy systems; however, a large line tension for the Sn–SiO 2 system is in line with results from the low-energy systems which indicate a positive correlation between the line tension and the solid–liquid interfacial tension.