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.

Wetting and infiltration of graphite materials by molten silicon

Abstract: The wetting and infiltration of various graphite materials by liquid silicon has been studied with the sessile drop method in argon at 1430 °C. Wetting and spreading of silicon on the graphite substrates is enhanced as the substrate roughness is increased, as a result of the accelarated dissolution of graphite in liquid silicon by the substrate roughening. The infiltration of molten silicon into the graphite materials is observed on the cross-section of the silicon/graphite interface. The vertical infiltration depth seems to be independent of the contact angles, but increases as the porosity (or pore size) of the graphite materials is increased. The lateral infiltration is also observed and seems to be dependent on the wetting behaviour.

Synthesis and physical properties of new layered silicates based on ionic liquids: improvement of thermal stability, mechanical behaviour and water permeability of PBAT nanocomposites

Abstract: Ionic liquids based on tetraalkylphosphonium and dialkyl imidazolium cations with long alkyl chains have been investigated as new surfactant agents for cationic exchange of lamellar silicates. The effect of the chemical nature of the ionic liquids on the thermal stability and on the surface energies of phosphonium-(MMT-201) and imidazolium-(MMT-I) treated montmorillonites have been studied by thermogravimetric analysis (TGA) and sessile drop method. Poly(butylene adipate-co-terephthalate) (PBAT) nanocomposites filled with a low amount of these modified-montmorillonites (2, 5 wt%) have been processed by melt mixing using a twin screw extruder. The mechanical, thermal, water and gas barrier properties of the corresponding nanocomposites as well as the distribution of the clay layers in PBAT matrix were determined.

The surface tension of liquid silver alloys: Part II. Ag−O alloys

Abstract: The surface tensions of liquid Ag-O alloys have been determined by the sessile drop method. The surface activity of oxygen, as measured by −(dσ/dX O)XO→0j, where σ is the surface tension of the metal andX O the mole fraction of oxygen, is quite large and equals 3.80×105 dyne per cm at 980°C and 1.35×105 dyne per cm at 1108°C. The heat of adsorption of oxygen is estimated to be of the order of 30 kcal per mole. Application of the monolayer approximation shows that liquid silver becomes saturated with oxygen when each adsorbed oxygen atom occupies an area of 33±5A2. Small additions of platinum to silver do not change the characteristics of the adsorption of oxygen appreciably. An analysis of the data is consistent with the conclusion that saturation of the surface of liquid silver with oxygen results from the formation of an ionic two-dimensional compound at the surface. This hypothesis is tested in the case of several other systems and yields satisfactory results. The structure of these compounds is discussed. In the case of the Ag-O system, it appears to correspond to the stoichiometry Ag3O.

Hysteresis during contact angles measurement.

Abstract: A theory, based on the presence of an adsorbed film in the vicinity of the triple contact line, provides a molecular interpretation of intrinsic hysteresis during the measurement of static contact angles. Static contact angles are measured by placing a sessile drop on top of a flat solid surface. If the solid surface has not been previously in contact with a vapor phase saturated with the molecules of the liquid phase, the solid surface is free of adsorbed liquid molecules. In the absence of an adsorbed film, molecular forces configure an advancing contact angle larger than the static contact angle. After some time, due to an evaporation/adsorption process, the interface of the drop coexists with an adsorbed film of liquid molecules as part of the equilibrium configuration, denoted as the static contact angle. This equilibrium configuration is metastable because the droplet has a larger vapor pressure than the surrounding flat film. As the drop evaporates, the vapor/liquid interface contracts and the apparent contact line moves towards the center of the drop. During this process, the film left behind is thicker than the adsorbed film and molecular attraction results in a receding contact angle, smaller than the equilibrium contact angle.