Forced wetting by a reactive fluid

Collège de France - 11 place M. Berthelot, 75231 Paris Cedex 05, France

Received: 26 May 1997
Accepted: 30 June 1997

Abstract

We consider a plate plunging at constant velocity V into a reactive liquid. The chemical reaction between liquid and plate decreases the wettability of the plate. We also assume a certain hysteresis of the contact angle. This then leads us to predict a stick-slip cycle at low V. During a long portion of the cycle, the contact line is pinned; the contact angle increases; and the liquid/solid interface near the line is chemically transformed. In a second (short) portion of the cycle, the line jumps and advances on an unreacted surface (which is more wettable). To ensure a significant difference in wettability, the reaction level reached in the pinned regime must be high. This imposes low velocities —roughly smaller than the ratio meniscus size/reaction time.