The Wetting of Alumina Substrate by Liquid Gold

Abstract The wetting of an Al2O3 substrate by liquid gold was investigated by means of the sessile-drop method in an atmosphere of argon. An empirical relation was estabilished between the contact angle and the temperature or surface tension of the liquid drop by the use of the diameter and the height of the sessile drop. The contact angle was constant with time, but decreased linearly with an increase in temperature. The variation in the contact angle with temperature is correlated with the surface tension of the sessile drop. The surface tension of liquid gold was obtained as 933 dyn cm−1 at 1080 °C and 917 dyn cm−1 at 1100 °C and the temperature coefficient of the surface tension of liquid could be estimated to be −0.80 dyn cm−1 °C−1. The critical surface tension (γc) and the surface tension of liquid gold at 0 K of Al2O3 (γLV°) were 20 and 2015 dyn cm−1, respectively.