Investigation of Field-Activation in Combustion Synthesis: The Use of Field as a Processing Parameter

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ABSTRACT CTS-9616768 This study is an investigation of the use of electric fields in self - propagating high-temperature (combustion) synthesis (SHS). It builds on previous work to develop an understanding of the interactions between electromagnetic fields and self-sustaining combustion waves. The focus is on the macrokinetics of wave propagation in the presence of a field and on microstructural developments within the combustion zone. Models and experiments are used to study field activation as a function of thermophysical properties of reactants and products. Relationships of interest include the effects of the field on the velocity and temperature of the combustion wave, on phase transformation, and on modal change (steady/nonsteady state) in wave propagation. The effect of the field on the mechanism of combustion is investigated using the Boddington-Laye analysis of temperature profiles and compared to experimental observations on profiles in the combustion zone. The results are extended to determine the effect of the field on compositional distribution in functionally-graded materials. Incorporated into this study are collaborations with two Italian research groups. Dr. Umberto Anselmi-Tamburini of Pavia will participate in the study of field effects on the kinetics and mechanisms of the combustion process. Dr. Giacomo Cao of Cagliari will be involved in studies of formation of intermetallic compounds by SHS. Understanding the interactions between electric fields and self-propagating combustion systems will enable the use of the field as a processing parameter in the synthesis and consolidation materials. ***