Reaction induced anomalous temperature dependence of equilibrium contact angle of TiZr based glass forming melt on Al 2 O 3 substrate

Abstract

The wetting behaviours and interface reactions in Ti_32·8Zr_30·2Ni_5·3Cu₉Be_22·7/Al₂O₃ system were investigated using a sessile drop technique at 1073–1223 K in high vacuum. Both the equilibrium contact angles and the interface reactions largely depend on the test temperature. The equilibrium contact angle first decreases and then increases with the increase in temperature. The minimum of the equilibrium contact angle is 21° at 1143 K. The reason for the anomalous change of equilibrium contact angle is the change of the interface structure. At low temperature, the adsorption of α-Ti solid solution at the interface and the formation of Ti_0·5Zr_0·5O_0·33 in the precursor film are beneficial to the wettability. With further increasing the temperature to 1173 K, the formation of ionic α-BeO is responsible for the deterioration in wettability.