International Journal of Self-Propagating High-Temperature Synthesis

Influence of applied pressure P and intensity of Joule heating on electrothermal explosion (ETE) in Ti–C blends placed in a porous electroconducting envelope was studied by using a home-made experimental setup. A distinctive feature of this system is non-linear warm-up prior to initiation of ETE. A non-linear temperature growth during pre-explosion warm-up was associated with gradual decrease in the electrical resistance of the sample caused by intensification of mass transfer processes leading to an increase in current density and hence in heating rate. During the warm-up period, the extent of conversion was found to attain a value of about 15%. In classical theory of gasless combustion, chemical reaction within the warm-up zone is neglected and it is postulated that combustion reaction gets started at temperatures close to the melting point of a low-melting reagent. Our results cast some doubt on the validity of the above adoptions and thus shed new light on the mechanism of SHS reactions in heterogeneous systems.