A quasi-containerless pendant drop method for surface tension measurements on molten metals and alloys

Abstract

A quasi-containerles pendant drop method for measuring the surface tension of molten metals and alloys is being developed. The technique involves melting the end of a high-purity metal rod by bombardment with an electron beam to form a pendant drop under ultra-high-vacuum conditions to minimize surface contamination. The magnified image of the drop is captured from a high-resolution CCD camera. The digitized image of the drop is then analyzed to compute the surface tension. A computer program has been developed that reads the pixel intensities from a graphics file containing the digital image. The code searches for the edge of the drop along rows and columns of pixels and stores the edge coordinates in an array. It then computes an optimized theoretical drop shape by solving the Young-Lapface differential equation from which the quantity of surface tension is deduced. This technique has been demonstrated with the surface tension measurement of molten zirconium metal.