Study of wetting promotion mechanism of Pb/Cu interface assisted by ultrasonic vibration from molecular dynamics simulation and experiments

Abstract

In the paper, the molecular dynamics method was used to study the wetting promotion mechanism of liquid Pb/solid Cu system under ultrasonic vibration, which provided theoretical guidance for the application of ultrasonic wetting. The result showed that both ultrasound and temperature increase could improve the wettability of the system by promoting the dissolution and diffusion of the solid-liquid interface. However, ultrasound had a more obvious promotion effect. At 900K, the contact angle without ultrasound was 22.3°, while the contact angle with ultrasound was reduced to 0°, and the system was completely wetted. In addition, it was found that ultrasonic frequency had a significant effect on wettability. The 250 GHz ultrasonic vibration had an obvious effect on the wetting, but there were a large number of Cu atoms dissolved at the edge of the droplet, which hindered the spreading of the droplet, while the 25 GHz ultrasonic frequency only promoted the spreading of the droplet. In addition, experiment at different temperatures confirmed that ultrasonic vibration improved the wettability of the system. The wetting promotion mechanism of ultrasonic was that ultrasonic vibration caused the system to generate tension and pressure at the solid-liquid interface, which promoted the spreading of droplet and the diffusion of interface atoms, and reduced the solid-liquid interface energy and equilibrium contact angle.