Surface tension measurements of refractory liquid metals by the pendant drop method under ultrahigh vacuum conditions: Extension and comments on Tate’s law

Abstract

The pendant drop method, used in an ultrahigh vacuum drop tube, allowed new determinations of the liquid surface tension of the refractory metals. After a description of the melting apparatus, the amazing reproducibility in terms of droplets masses (≂0.6%) observed is discussed herein. Evidence is given of the harmful action of hydrogen bubbles contained in the commercial rods. Working with very thin wires (down to 0.3 mm), a variation curve for the Harkin’s correction factor of Tate’s law in its untabulated range is proposed. The validity of the representation of this factor is discussed via a dimensional analysis. Finally, new values of σLV for pure Re (2.510 J m−2), W (2.310 J m−2), Ta (2.010 J m−2), Nb (1.840 J m−2), Ir (2.140 J m−2), and Zr (1.435 J m−2) are proposed.