Characteristics of thin liquid film under an external electric field

Cavitation is a serious problem in bearings when they are used in the electric field. When an external electric field (EEF) was applied on a lubricant film with a thickness about a few nanometers, which was in a nanogap between a smooth plate coated with a SiO2 layer and a highly polished steel ball, some gas micro-bubbles emerged around the edge of the central contact region and then moved away in the radial direction from the central region. Experimental results indicated that the emergence of the bubbles was largely dependent on the polarity of the liquid, the external voltage, and the pressure in the central contact region. It is thought that the emergence of the bubbles is due to the vibration of the liquid surface or overheating of the liquid, and the power pushing the micro-bubbles to move are from the pressure difference and the electric field difference on edge of the central region. The discussion of the difference between the static case and dynamic one is emphasized with our proposed mechanism further.