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.

Measurements of Line Tension for Solid−Liquid−Vapor Systems Using Drop Size Dependence of Contact Angles and Its Correlation with Solid−Liquid Interfacial Tension

Abstract: According to the modified Young equation, one of the direct ways of measuring line tension for solid−liquid−vapor systems takes advantage of the dependence of the contact angle on the radius of curvature of the three-phase line. This approach was used to determine line tension measurements for six organic liquids on two different self-assembled monolayer (SAM) surfaces (mixed monolayers of methyl and carboxylic acid terminated alkanethiol on gold at two different composition levels). Low-rate advancing contact angles were measured using Axisymmetric Drop Shape Analysis-Profile (ADSA-P). The general trend observed for each system was that the contact angle decreases as the radius of the three-phase line for the sessile drop increases from approximately 1 to 5 mm. It was found that the drop size dependence of contact angles can be interpreted as being due to a positive line tension. The line tension values are all in the order of 10-6 J/m. Also a correlation was observed between the line tension and the sol...

Modeling the infiltration kinetics of molten aluminum into porous titanium carbide

Abstract: Capillary-induced melt infiltration is an attractive method of fabricating metal/ceramic composites, as it offers the advantage of producing material with a high ceramic content and near-net-shape fabrication, without the use of an external force. In this work, the kinetics of infiltration of molten Al in TiC preforms, having a pore size of approximately 1 µm and porosity ranging from 20 to 40 pct, were investigated. The rate of infiltration was continuously monitored using a Thermo-Gravimetric analyzer (TGA), which measured the weight change of the preform as the metal intruded the sample. Infiltration profiles where generated over a temperature range of 860 °C to 1085 °C. At lower temperatures, an incubation period was evident in the profiles. The average activation energy for the different preforms was 90 kJ/mol, indicating that some form of mass-transfer mechanism was involved in driving the process. Furthermore, sessile drop tests showed an unstable wetting angle over a long period of time. Such wetting kinetics were responsible for the incubation period during the infiltration. The infiltration rate was also seen to be slower as the preform density increased. This was due to the tortuous nature of the channels and was characterized using curves obtained for liquids infiltrating the same preforms at room temperature. Both the tortuosity and the unstable contact angle have to be considered when modeling the infiltration kinetics of such a system. The existing model was therefore modified by incorporating terms to describe the process more accurately. A good correlation with the experimental data was seen to exist.