Study of Contact Angle Hysteresis. In Relation to Boiling Surface Wettability.

In nucleate and transition boiling, the wettability of a heated surface plays an important role. Up to now, the contact angle has been a common measure of surface wettability. But because of contact angle hysteresis, measuring it from the shape of a liquid droplet on a horizontal solid surface may have almost no meaning. In this study, the hysteresis is studied theoretically and effects of surface energetics, roughness and temperature on wettability are investigated experimentally by measuring contact angle under various conditions. As a result, a new measure of solid surface wettability is proposed.