DYNAMICS OF WETTING IN REACTIVE METAL-CERAMIC SYSTEMS

Dynamics of wetting of metallic drops on smooth ceramic surfaces are d iscussed for the case of liquid-solid couples leading to the formation of a continuous layer of a reaction product at the interface, by reac tion between a component of the liquid and the solid substrate. This p aper is focused mainly on the following two questions: (i) the driving force of reactive wetting, i.e. the origin of this force and the cruc ial question of the final contact angle in a reactive system and (ii) the different processes which can be rate-limiting, namely the viscous flow, the diffusion within the drop and chemical kinetics at the trip le line. From experimental results on model systems published in the l ast three years, clear answers to point (i) were given. Current experi mental and theoretical results on spreading kinetics are the starting point For a fundamental approach to these complex kinetic phenomena. ( C) 1998 Acta Metallurgica Inc.