Showing papers on "Sessile drop technique published in 1978"

The wetting of alumina and vitreous carbon by copper-tin-titanium alloys

Abstract: The wetting behaviour of copper-rich copper-tin-titanium alloys on alumina and vitreous carbon substrates at 1050 to 1150° C has been determined using the sessile drop technique. Substantial additions of titanium induce copper to wet, but tin has no significant effect. However, the simultaneous addition of tin and titanium is markedly beneficial, particularly with vitreous carbon. Metallographic and EPMA studies showed that titanium-rich reaction products were formed at the interfaces. The wetting and reactivity data are interpreted in terms of surface enrichment of the alloys by tin and of a disproportionately greater activity of titanium in tin.

Techniques for Measuring Adhesive Energies in Metal/Ceramic Systems

Abstract: The adhesive energies of nickel on thorium dioxide (ThO 2 ), nickel/ chromium (80/20) on ThO 2 , and iron/nickel/chromium (304 stainless steel) on aluminum oxide (Al 2 O 3 ) were determined at temperatures ranging from roughly 200°C (360°F) below the melting point of the metallic component to approximately 50°C (90°F) above. The technique involves the measurement of the average surface free energy for the solid metals and liquid metal drops utilizing the zero-creep and sessile-drop shape concepts, respectively. Measurements of equilibrium energetics and associated geometries as well as the contact angles at metallic particles in contact with the ceramic substrates are described using the techniques of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Measurements of surface free energy of nickel/chromium and stainless steel drops equilibrated at temperatures below the melting point and utilizing the sessile-drop method are compared with those determined by the zero-creep method. The results of this investigation represent the first systematic study of the variation of adhesive energy of a metal/ceramic system with temperature, and the comparison of surface free energies determined from equilibrium particle shapes with zero-creep measurements of wires of the same material in the solid state.