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

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.