Experimental study on the interaction forces between water droplets and mineral surfaces

Abstract

Research on the interaction between droplets and solids is of great significance for fundamental research and practical applications. This work comprehensively investigated the interaction process between millimeter-scale water droplets and three minerals (kaolinite, SiO 2 and Al 2 O 3 ) and directly measured their interaction forces, including wetting force, maximum adhesion force and detachment force, using the macroscopic force measurement technology and camera technology. In addition, the influence of surface wettability and impact distance on the interaction forces was examined, and the relationships between surface wettability, impact distance and interaction forces were also discussed. Results showed that at the same impact distance, the wetting force, maximum adhesion force and detachment force between water droplets and mineral substrates increased with increasing the hydrophilicity of mineral surface. Regardless of the mineral type, due to the enlargement of TPC line length or the expansion of contact area, both wetting force and maximum adhesion force increased as an increase in impact distance, while the detachment force exhibited an opposite trend. Moreover, irrespective of impact distance, the interaction forces of water-kaolinite (60.3°) were always between those of water-SiO 2 (54.5°) and those of water-Al 2 O 3 (94.5°), indicating that surface wettability of minerals was the dominant factor determining the interaction forces between water droplet-mineral surface. These results can provide guidance for studying the interaction between liquid droplets and solid surfaces from the perspective of macroscopic forces.