Low-temperature combustion waves in low-energy K_2TaF_7-Si-additive systems

摘要

This work presents the use of a thermocouple technique for measuring temperature profiles in a condensed K_2TaF_7-Si system blended with a small amount of Teflon (C_2F_4)_n] or potassium chlorate (KClO_3). A base experiment is described in detail to demonstrate the ability of the system to react under a low-rate self-sustaining mode at ambient temperature. The ignition temperatures, temperature-time profiles, combustion parameters, and final products are presented with respect to the additive concentration. The combustion processes begin at 340 and 450 ℃ for the KClO_3 and (C_2F_4)_n-containing mixtures, respectively. The maximum temperatures of both KClO_3 and (C_2F_7)_n-containing mixtures range from 470 to 960 ℃ and the combustion self-propagates along the sample at a speed of 0.01-0.08 cm/s. The solid combustion products produced under the optimized conditions include fine powders of tantalum, tantalum carbide, and tantalum silicides. The chemical mechanism of the combustion process and reaction parameters responsible for low-speed wave propagation are presented and discussed.