The effect of additives on the burning rate of silicon-calcium sulfate pyrotechnic delay compositions

Abstract

The effect of fuel particle size as well as the influence of inert and reactive additives on the burning rate of the Si-CaSO4 composition was evaluated. The burning rate decreased with increase in fuel particle size, while the enthalpy remained constant. Addition of fuels to the base composition increased the burning rate, with an increase from 12.5 mm s-1 to 43 mm s-1 being recorded upon 10 wt. % Al addition. Ternary mixtures of silicon, calcium sulfate and an additional oxidizer generally decreased the burning rate, with the exception of bismuth trioxide where it increased. The Si-CaSO4 formulation was found to be sensitive to the presence of inert material, addition of as little as 1 wt. % fumed silica stifled combustion in the aluminium tubes.