Modeling solution for electric field-activated combustion synthesis

A computer model of the effect of an electric field on self-propagating high-temperature synthesis (SHS) reactions is presented. Using the synthesis of SiC as a model, the analysis showed that, in addition to the chemical heat release, the combustion zone also includes heat release from an electric source, a value equivalent to sigma E-2, where sigma is the conductivity and E is the field. Using a two-dimensional Fourier heat balance equation and accounting for the field contribution in terms of Joule heating, a set of equations were developed. Solutions of these were made by a finite difference scheme, coupling the nonlinear partial differential equations. The imposition of this electric field results in a highly localized distribution of the current density. The current is primarily located at the reaction front where 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 voltage, it is shown that the velocity of the combustion wave is linearly proportional to the field. (C) 1998 Published by Elsevier Science B.V. All rights reserved.