Modeling Silicon Carbide Synthesis on a Submicrometric Scale

Abstract

We build a model, on a mesoscopic, submicrometric scale, describing the formation of silicon carbide during heating at a constant rate and holding at a temperature smaller than the eutectic temperature of carbon and silicon. Simulating a two-dimensional cut of the initial mixture of powders, we show that the mean number of contacts of a carbon plate with silicon increases as the typical size of the silicon grains decreases. We focus on the simulation of the dynamics of the reaction when the melting of silicon and the dissolution of carbon begin until some solid silicon remains. Precipitation of silicon carbide is assumed to obey a heterogeneous nucleation mechanism. The model sheds some light on the dynamics of dissolution−precipitation in self-heated synthesis and on the morphology of the resulting material. In agreement with the experiments, the simulations reproduce larger reaction speeds for smaller silicon grains. Larger silicon carbide grains are obtained when the typical sizes of silicon and carbon...