GENERATION OF ISOTHERMAL SPREADING DATA AND INTERFACIAL ENERGY DATA FOR LIQUID REACTIVE METALS ON CERAMIC SUBSTRATES - THE COPPER-TITANIUM ALUMINA SYSTEM

The sessile drop technique is frequently used to evaluate the wettabil ity and spreadability of liquid metals on ceramic substrates. In this study, the spreading kinetics of copper-20 wt % titanium alloys on pol ycrystalline alumina were evaluated based on measurements of spreading radius versus time. The process of spreading was monitored by an in s itu video recording system. The tests were performed using three diffe rent initial metal configurations. It was found that conventional sess ile drop testing configurations can not be used to generate isothermal spreading kinetics data because of significant spreading during the h eat-up cycle from the solid us temperature to the test temperature. An im proved sessile drop technique was developed which eliminated the n on-isothermal experience by introducing the liquid copper to the solid titanium/alumina at the desired testing temperature. Using this techn ique, only a few seconds of data were lost (while the liquid copper di ssolved the solid titanium). Because very limited interfacial energy d ata exist for the copper-titanium/alumina system, especially at higher titanium concentrations, the equilibrium contact angle, the solid-liq uid interfacial energy, and the work of adhesion from 1000 to 1300 deg rees C are also presented.