MASS-TRANSPORT PHENOMENA AT THE LIQUID METAL SUBSTRATE (METAL, CARBIDE) INTERFACE/

We have developed a model that describes surface mass transport in dis similar materials such as liquid metal/substrate (metal, structural ce ramic) and verified the model with experimental data taken from the li terature and generated in our research on liquid aluminum and silicon carbide at 933 and 1253 K. Knowing the size of contact angles of drops on substrates as a function of time and temperature in a controlled a tmosphere allows the calculation of apparent surface diffusion coeffic ients that are characteristic of the systems under consideration. Appa rent surface diffusion appear to be two components related to adhesion al wetting (physical effect), D-S, and reactive wetting (chemical effe ct), D-r, and can be expressed by the following equation: D-S + D-r = (gamma(LV)/eta) cos theta(e) lambda LT = constant, where gamma(LV) and eta are the surface tension and viscosity of the liquid, respectively ; lambda is a geometrical roughness of the solid surface; and theta(e) is a contact angle at equilibrium. (C) 1997 Elsevier Science S.A.