Modeling solution for electric field-activated combustion synthesis

A computer model of the effect of an electric field on self-propagating hig h-temperature synthesis (SHS) reactions is presented. Using the synthesis o f SiC as a model, the analysis showed that, in addition to the chemical hea t release, the combustion zone also includes heat release from an electric source, a value equivalent to sigma E-2, where sigma is the conductivity an d E is the field. Using a two-dimensional Fourier heat balance equation and accounting for the held contribution in terms of Joule heating, a set of e quations were developed. Solutions of these were made by a finite differenc e scheme, coupling the nonlinear partial differential equations. The imposi tion of this electric held results in a highly localized distribution of th e current density. The current is primarily located at the reaction front w here the temperature is the highest. This is consistent with the fact that the electrical conductivity increases with increasing temperature. From the dependence of the degree of conversion to the product on the applied volta ge, it is shown that the velocity of the combustion wave is linearly propor tional to the field. (C) 1998 Published by Elsevier Science B.V. All rights reserved.