Combustion properties of gas-generating pyrotechnics

This work focuses particularly on solid energetic materials designed to pro duce high-pressure gas for pressurizing or inflating devices. In cool gas g enerators sodium azide is often used. Unfortunately this chemical exhibits drawbacks concerning toxicity and yield of gas. Another gas-generating agen t is double base propellant, which has traditionally been used in the rocke t-industry. However, it delivers toxic and reactive gases and its combustio n temperature is high. In previous work a series of gas-generating material s have been proposed as potential alternatives fueled with double base prop ellant, azodicarbonamide, nitroguanidine, or guanidine nitrate and stoichio metricly oxidized with potassium nitrate or potassium perchlorate. The purp ose of this paper is to examine and compare the burning characteristics of the previously proposed compositions. To carry out this characterization. m ethods typical for propellant technology are used. Ignition delay, time fro m ignition to maximum pressure, burning rate. and absolute vivacity have be en investigated through closed vessel tests. Thanks to the use of a gaseous ignition mixture the form function of the tested grains is not deteriorate d. This leads to fairly reproducible results for the burning rate and the a bsolute vivacity, despite possible discrepancies in the ignition delay. In most of the studied cases, the addition of an oxidizer tends to improve the ignition delay and the time from ignition to maximum pressure. In addition the burning rate and absolute vivacity increase significantly. The only ex ception is double base propellant, where the presence of an oxidizer causes relatively minor changes in its combustion properties.