Perfect wettability of carbon by liquid aluminum achieved by a multifunctional flux

The wettability of carbon (graphite and glassy carbon) by liquid aluminum was studied. A special molten salt (flux) system was developed under which perfect wettability (a zero contact angle) of liquid aluminum was achieved on carbon surfaces. The principal component of the flux is K2TiF6 dissolved in a molten alkali chloride. K2TiF6 is a multifunctional flux component as it performs the following tasks: (i) dissolves the oxide layer covering liquid aluminum, (ii) through an exchange reaction with liquid aluminum it ensures the necessary amount of Ti dissolved in liquid Al, which is needed to cover the Al/C interface by TiC. As TiC is a metallic carbide, it is perfectly wetted by liquid Al-Ti alloys. In this paper, the conditions of perfect wettability of carbon by liquid Al under MCl-K2TiF6 molten salts (fluxes) are found as function of: (i) the basic component of the flux (MCl = LiCl, or NaCl-KCl or CsCl), (ii) K2TiF6 content of the flux, (iii) temperature, (iv) flux:Al weight ratio, (v) specific surface area of Al, and (vi) specific surface area of carbon. A simplified theoretical equation is derived to reproduce the experimental data.