Industrial & Engineering Chemistry Research, Vol.43, No.6, 1451-1459, 2004
Effect of surface topography of a rolled sheet on contact angle
The effect of surface topography of a rolled sheet on the contact angle of test liquids of various surface tension was studied using the Wilhelmy plate technique. The contact angle is lower when the liquid front moves along the rolling lines than transverse to the rolling lines due to the capillary rise along the grooves formed by the rolling lines. The contact angle is proportional to the surface topography parameter A(2), with a slope related to the surface tension of the test liquid. The observed phenomenon can be rationalized in terms of Cassie's theory, where the liquid spreading over the surface does not fill the entire topographic valleys, and this results in the formation of air cushions between the liquid and metal surfaces described by A(2). The effect of surface topography on the contact angle was only slightly influenced by the velocity of liquid front motion.