固体壁面付着気泡の溶解に対する固体溶存ガスの影響

抄録

Ultrasonic cleaning plays a key role in manufacturing process. Recent studies suggest that its cleaning mechanism is supported dominantly by the dynamics of acoustic cavitation bubbles. In this context, we favor to promote surface cavitation by having more gas bubble nuclei at cleaning surfaces. In this study, we experimentally study the effect of gases dissolved in solid substrates on the stability of gas bubble nuclei. In our experiments, polypropylene plates are used to create surface bubbles. Since their surface is hydrophobic, the surface bubbles are hemi-spherical in shape. Here, we consider the cases with the plates saturated or subsaturated with dissolved gases (air). It is confirmed from the experiments that the dissolution rate of the surface bubble is accelerated by having the gas-subsaturated plates. This is because of the gas transport from the bubble into the (subsaturated) solid phase. In the context of ultrasonic cavitation cleaning, it may be favorable to put cleaning samples under pressurazation before cleaning, which allows for having a larger number of stabilized gas bubble nuclei at their surfaces.