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.

Effect of gas evolution at solid-liquid interface on contact angle between liquid Si and SiO2

Abstract: The contact angle between liquid Si and SiO2 was measured with the sessile drop method at 1723 K. The contact angle changed very unusually due to the evolution of SiO gas at the solid/liquid interface. It was found that the real contact angle between liquid Si and SiO2 is about 80° or less at 1723 K though the apparent contact angle of 95° was observed for a long time during the experiment. The difference in the contact angle can be explained with a model of a composite material. Although the real contact angle is more important in a physical point of view, the apparent contact angle should be adopted in some cases such as simulation works.

Thermophysical Properties of Liquid In–Sn Alloys

Abstract: The surface tension of liquid In–Sn alloys was measured with three experimental techniques carried out in a protective atmosphere of a mixture of argon and hydrogen: tensiometric (in Chemnitz), and maximum bubble pressure and sessile drop (in Krakow). Attempts were undertaken to confirm the correlation of surface tension with electrical conductivity and viscosity and to compare them with literature data. The lack of such correlation or a weak one was observed, probably due to a slight negative departure of thermodynamic properties of liquid In–Sn alloys from ideal behavior. Both resistivity and viscosity correlated with the existence of In-rich β and Sn-rich γ phases of the In–Sn phase diagram. The mutual correlations of thermodynamic and physical properties, structure, and the type of phase diagram were confirmed previously for Li–Sn and Mg–Sn systems with evident negative thermodynamic departures from ideal behavior and with the occurrence of intermetallic compounds (IMCs) in the phase diagrams. Due to nearly the same values of surface tension and density of pure In and Sn, the concentration dependence on the surface tension and density was practically unchanged within an extensive range of temperatures in studies on Pb-free solders of binary and multicomponent alloys containing both metals. Thus, the beneficial influence of In on the wettability of In–Sn alloys was observed solely by the lowering of the contact angle.

Wetting prevention by thermal marangoni effect. Experimental and numerical simulation

Abstract: The behaviour of small liquid drops, hanging from a circular disk and approaching a flat wall at a different temperature is studied experimentally and numerically. If the pendant drop and the solid surface are at the same temperature and if the liquid wets the solid, the drop spreads over the surface forming a liquid bridge in times of the order of milliseconds. If the upper disk is heated and/or the solid surface is cooled, then the drop does not wet the wall, even if pressed against the surface, but it is deformed in a completely reversible way, similarly to an elastic material (e.g. like a rubber balloon). To investigate this unusual and intriguing phenomenon, a systematic experimental programme has been carried out on silicone oils (with different viscosities) and on diesel oils. At the same time the problem was studied numerically under the assumption that a thin air film exists between the drop and the solid surface. This film is formed by the entrainment of the surrounding air caused by the Marangoni flow directed, along the liquid surface, from the upper disk towards the contact zone. If suitable conditions are established, the pressure in the air film balances the pressure necessary to deform the liquid drop, preventing the wetting of the solid surface. The experimental results agree with the proposed numerical model. In particular the computed equilibrium air film thicknesses are compared with the thicknesses measured with a background illumination system and with an interferometric technique; a good agreement is found between numerical and experimental results, for different liquids and different geometrical configurations.

Joining of zirconia using zirconium-based alloys

Abstract: The contact angles of Zr-Ni, Zr-Cu and Zr-Co alloys against PSZ were measured by the sessile drop method. Each alloy wetted PSZ very well. Zr-Co alloys showed a different behaviour. Joints of PSZ plates were obtained using Zr-17Ni alloy. At the joint interface, internal oxidation of zirconium occurred. The fracture shear strength of this joint was 55 MPa.

Thermal Expansion, Electrical Resistivity, and Spreading Area of Sn-Zn-In Alloys

Abstract: Thermal expansion and electrical resistivity of alloys based on Sn-Zn eutectic with 0.5, 1.0, 1.5, and 4.0 wt.% additions of In were studied. Thermal expansion measurements were performed using thermomechanical analysis tester over 223-373 K temperature range. Electrical resistivity measurements were performed with four-probe method over 298-423 K temperature range. The electrical resistivity of alloys increases linearly with temperature and concentration of In; also coefficient of thermal expansion of the studied alloys increases with In concentration. Scanning electron microscopy revealed simple eutectic microstructure with In dissolved in Sn-rich matrix. The results obtained were compared with the available literature data. Spreading tests on Cu of Sn-8.8Zn alloys with 0.5, 1.0, and 1.5 at.% of In were performed. Wetting tests were performed at 250 °C, by sessile drop method, by means of flux, and wetting times were 3, 8, 15, 30, and 60 min. In general, no clear effect of wetting time on spreading was observed.