Joonho Lee

The surface tension of liquid Sn-X (X=Ag, Cu) alloys was measured by the constrained drop method in the temperatures between 700 and 1500 K across whole composition range. Surface tension of the alloys increased with the content of Ag and Cu, and the temperature coefficient of the surface tension (dσ/dT) had both positive and negative values. Experimental results were compared with the calculated results based on Butler's model. The calculated results reasonably accorded with the measurements. T

Surface tension of liquid iron is strongly influenced by the adsorption of sulfur. In this study, surface tensions of liquid Fe-S alloys at 1823 K were measured by the sessile drop technique in a purified argon atmosphere. Experimental results were compared with the model based on Butler's equations considering the effect of size and interactions of the adsorbed elements assuming that the system was composed of Fe-"FeS" binary. The model could evaluate the surface tension and the adsorption of s

Accurate measurements of surface tension of liquid metals having low capillary constants (the ratio between density (ρ) and surface tension (σ), ρ/σ) have been attempted using the constrained drop method. High accuracy of surface tension measurements was obtained by making a large axi-symmetric liquid drop and adopting a developed image capturing system composed of a high-resolution charge-coupled device (CCD) camera, an additional CCD camera to adjust the level of the metal drop and a He-Ne las

It is usually known that the surface tension of liquid metals and alloys decreases with increasing temperature, i.e., the temperature dependence of the surface tension is negative. We found, however, that some liquid alloys, which have large difference of the surface tension of pure components, show positive temperature dependence in certain composition ranges. Some Pb-free alloys, for which information on the surface tension is indispensable to be developed as environmental-friendly material, c

Energy consumption in the industrial sector can be significantly reduced by improving heat transfer rates in heat exchanger circuits, pool boiling, metal cutting industries, etc. Numerous energy-related issues can be overcome to a large extent by improving heat flow properties by utilizing nanofluids. The present contribution reviews the improvement in thermophysical properties of metal oxide-based nanofluids. Key parameters affecting the thermophysical properties of nanofluids, such as particle

We investigate equilibrium transport of gas–water mixtures, such as CO2–water, O2–water and H2–water mixtures, in carbon nanotubes using molecular dynamics simulations. Our results indicate that gases are selectively physisorbed in carbon nanotubes forming single-file gas chains. Once the single-file gas chains are formed, they prevent entry of water into the nanotube, suggesting that the presence of gas molecules can significantly affect the equilibrium transport of water in carbon nanotubes. T

The behavior of oxygen adsorption on the surface of liquid Cu-Ag alloys was investigated by measuring their surface tension (σ) with the sessile drop method in the oxygen partial pressures (po2) between 2.5 × 10−11 and 2.5 × 10−3 Pa. The oxygen adsorption (the surface excess concentration of oxygen) was calculated from the slope of dσ/d ln po2 by applying Gibbs adsorption isotherm, for liquid Cu, Cu-5 at%Ag, Cu-10 at%Ag, Cu-20 at%Ag and Ag. It was found that the oxygen adsorption increased with