Sessile drop technique

About: Sessile drop technique is a research topic. Over the lifetime, 2827 publications have been published within this topic receiving 68943 citations.

Interfacial phenomena in some slag-metal reactions

Abstract: In the present work, the change of the interfacial tension at the slag-metal interface for sulfur transfer between molten iron, slag, and gas phases was monitored by X-ray sessile drop method in dynamic mode in the temperature range of 1830 to 1891 K. The experiments were carried out with pure iron samples immersed partly or fully in the slag phase. The slag consisted of 30 wt pct CaO, 50 wt pct Al2O3, and 20 wt pct SiO2 (alumina saturated at the experimental temperatures) with additions of FeO. Metal and slag samples contained in alumina crucibles were exposed to a CO-CO2-SO2-Ar gas mixture with defined oxygen and sulfur partial pressures, and the change of the shape of the metal drop was determined as a function of time. The equipment and the technique were calibrated by measurements of the surface tensions of the pure Cu, Ni, and Fe containing two different amounts of dissolved oxygen. A theoretical model was developed to determine the sulfur content of the metal as a function of time on the basis of sulfur diffusion in the slag and metal phases as well as surface tension-induced flow on the metal drop surface. Attempts were made to compute the interfacial tensions on the basis of force balance.

A new model to predict the influence of surface temperature on contact angle

Abstract: The measurement of the equilibrium contact angle (ECA) of a weakly evaporating sessile drop becomes very challenging when the temperatures are higher than ambient temperature. Since the ECA is a critical input parameter for numerical simulations of diabatic processes, it is relevant to know the variation of the ECA with the fluid and wall temperatures. Several research groups have studied the effect of temperature on ECA either experimentally, with direct measures, or numerically, using molecular dynamic simulations. However, there is some disagreement between the authors. In this paper two possible theoretical models are presented, describing how the ECA varies with the surface temperature. These two models (called Decreasing Trend Model and Unsymmetrical Trend Model, respectively) are compared with experimental measurements. Within the experimental errors, the equilibrium contact angle shows a decrease with increasing surface temperatures on the hydrophilic surface. Conversely the ECA appears approximately constant on hydrophobic surfaces for increasing wall temperatures. The two conclusions for practical applications for weakly evaporating conditions are that (i) the higher the ECA, the smaller is the effect of the surface temperature, (ii) a good evaluation of the decrease of the ECA with the surface temperature can be obtained by the proposed DTM approach.

Characterization of Dynamic Stick-and-Break Wetting Behavior for Various Liquids on the Surface of a Highly Viscoelastic Polymer

Abstract: A thermally stripped acrylic polymer was wet with a series of liquids possessing a broad range of properties. Previously, novel wetting behavior by water was reported for the polymer, which included the formation of a wetting ridge structure substantially larger than those reported elsewhere and the complete halting of the three-phase line. This allows metastable angles ranging from 0° to greater than 150° to be achieved through changes in the sessile drop volume. Greater advancing angles are prevented by the collapse of the drop, producing what has been described as stick-and-break propagation. In Wilhelmy plate experiments for metal plates coated with the polymer, this mechanism produces a quasi-periodic pattern of lines composed of ridge structures. Similar behavior was observed for all liquids tested. Differences were observed in the maximum force measured with a tensiometer (pinning force) and the average distance between ridges for the formed pattern (pinning distance). These quantities are shown to...