There have been a large number of papers on the surface tensions of metals since Keene published his critical review in 1993. Consequently, current data for both the surface tensions of metals and their temperature dependencies have been critically assessed and recommended values are given. Experimental uncertainties can arise from two sources: systematic errors associated with the experimental methods (typically ±2%) and changes in surface tension arising from oxygen contamination of the specimen. Uncertainties arising from the latter can be variable.

Review of surface tension data for metallic elements and alloys: Part 1 – Pure metals

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 (d�= 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. The effect of thermo-physical parameters on the surface tension and the temperature coefficient were examined using the model. It was found that the temperature coefficient increases as the difference in the surface tension of component metals or the excess free energy increases in the high composition range of the component metal having higher surface tension, because of the surface enhancement of the other component metal.

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Surface Tension and its Temperature Coefficient of Liquid Sn-X (X=Ag, Cu) Alloys

Oxygen tensioactivity on liquid-metal drops.

The influence of oxygen on the surface tension of liquid metals is a topic of undoubted interest as the formation of oxide films, or even oxygen contamination of the metal interface, represents the main source of error indetermining the surface tension. The evaluation of gas-atmosphere mass exchanges under stationary conditions allows the evaluation of an effective oxygen pressure at which the oxidation of metal becomes evident. This effective oxygen pressure can be considered as a property of the system and, according to experimental evidence, can be many orders of magnitude greater than the equilibrium pressure. The measurement of the surface tension is a good way of studying interface properties, their temporal change and their connections to transport and reaction rates. This paper represents a review of a work undertaken with the aim of understanding oxygen mass transport at the liquid metal surface in relation to the study of capillary phenomena at high temperature.

Oxygen tensioactivity on liquid-metal drops

In this study, Sn-Ag nano solders of three different compositions (Sn-10 mass%Ag, Sn-35 mass%Ag and Sn-65 mass%Ag) were synthesized via arc-discharge process The properties of Sn-Ag nano solders were analyzed using X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX), and Differential Scanning Calorimetry (DSC) Particle size relatively widely ranged from 10 nm to 340 nm For Sn-10 mass%Ag and Sn-35 mass%Ag, average size was 200� 240 nm, and that for Sn-65 mass%Ag was 40� 50 nm with some extra-ordinary large particles of � 100 nm The melting points of the prepared SnAg nano solders were examined with DSC at different heating rates 1 K, 3 K and 5 K/min The congruent melting point of Sn-Ag nano solders was found to be 487 K [doi:102320/matertransMJ201013]

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Preparation and Thermal Analysis of Sn-Ag Nano Solders

The effect of oxygen on the surface tension of liquid Ag-Sn alloys used as one of the main components in lead-free soldering alloys was measured by the sessile drop method. The surface tension of liquid Ag-Sn alloys decreased with increasing tin content. The effect of oxygen was investigated for oxygen partial pressure ranging from about 10 - 1 7 to 10 - 1 2 atm. The effect of oxygen on the surface tension of liquid Ag-Sn alloys is closer to pure tin rather than pure silver. Thermodynamic simulation using Butler's equation showed that the surface of liquid Ag-Sn alloys is enriched with tin. Accordingly, the effect of oxygen adsorption on the surface tension of liquid Ag-Sn alloys was considered to be closer to that of tin than silver.

Masaya Yamamoto

Papers

Effect of oxygen on surface tension of liquid Ag-Sn alloys