Pressure and temperature effects on burning rate of the silicon - red lead system

Abstract

The effects of ambient pressure ranging from 101 up to 3040 kPa and temperature from 233 up to 353 K on burning rate of both high and low fuel content Si-Pb3O4 mixtures have been investigated. Also tests have been made to further reduce pressure effects using additions of metal fluorides. Sodium and calcium fluorides applied diminished the pressure dependency of burning rate for the low fuel content mixture, while for that containing high amount of silicon they left it almost unaffected. This different behavior of the mixtures could be probably attributed to the difference in their combustion mechanism. Ambient temperature influenced the rate of burning in dependence on fuel content too. Temperature coefficients determined consist well with the assumption on prevailing solid state reaction mechanism of Si-Pb3O4 system, which is on the other hand complemented for silicon poor mixes with convective transport of heat. Pressure coefficients have not been calculated because of rather irregular shape of pressure - burning rate curves but the dependency is clearly recognizable for both the mixtures although the pressure influence on rate of burning was not very heavy, which is to be expected for this typical delay composition.