Postinduction processes during thermal explosion in the systems “porous material–reactive gas–solid product”

A complete solution of the unsteady-state filtration problem of thermal explosion incorporating the postinduction period is given for the first time. The paper describes a study of the temperature-field dynamics, pore-gas pressure, and the degree of condensed-phase conversion versus the reactive-gas deficiency in a reactive porous material. Focus is on the formation and propagation of frontal regimes of exothermic chemical reactions (their number, direction, and velocity of propagation, degree of condensed-phase conversion at the front). The study revealed “double self-ignition” phenomena and combustion-wave propagation regimes with incomplete conversion at the front. A surface regime of thermal explosion limited by gas filtration from the outside was considered. The regularities in the dynamics of the exothermic chemical reaction found in the present study allow one to qualitatively control high-temperature synthesis under thermal explosion conditions.