Combustion features of dispersed aluminum and boron in high-energy composition

Abstract

Combustion of dispersed metals in an oxidizing environment is of practical interest, which is related to the prediction of characteristics of high-energy compositions (HECs) containing metal powders, as well as the characteristics of various propulsion systems and gas generators. The research studies peculiarities of ignition and combustion of dispersed systems of Al, B and Al-B mixture in gas products formed during thermal decomposition and combustion of HEC components. In the study of the characteristics of ignition and combustion, the development of flame processes, a continuous CO2 laser (high-speed radiant heating) and a continuous-pressure flow bomb (stationary combustion), including the filter system for the capture of condensed combustion products (CCPs) were applied. It was found that the high reactivity of dispersed Al reduces the ignition time and increases the burning rate of HECs, and increases the volume fraction of fine condensed particles. The use of amorphous B or Al-B mixture (17.2/82.8 mass ratio) increases the ignition time (up to 62%) and significantly reduces the burning rate of HECs, at the same time, the volume share of large CCPs increases due to the melting of the oxide layer on the surface of B particles and their increased cohesion. Analysis of CCPs showed that fine and large agglomerate particles were formed on the surface of the reactive HEC layer, which contain oxides of the metals used. When Al particles are burned together with B particles, complex oxides (aluminum borates) can be formed.