Oxidation kinetics and combustion of boron particles with modified surface

This work is aimed to modify a commercial 95% pure boron powder to improve its ignition. The powder is processed using acetonitrile to dissolve the oxidized and hydrated surface layers. The washed powder re-oxidizes and agglomerates readily, which can be prevented by additionally washing it in toluene and other liquid hydrocarbons, prior to exposing it to an oxidizing atmosphere. The presence and removal of the hydrated oxide layer and oxidation of boron powders are studied using thermo-gravimetry. The processed powders are shown to retain the active boron present in the starting material and maintain their reactivity after extended exposure to an oxidizing environment. The powders are also injected in a pre-mixed air-acetylene flame and their ignition and combustion are studied based on their optical emission. Flame temperature is measured using optical emission spectroscopy. Powder particles washed in acetonitrile, toluene and hexane exhibit substantially shorter ignition delays compared to the starting commercial boron particles. Full-fledged combustion is unaffected by this processing: both, burn times and flame temperatures are nearly identical for commercial and modified powder particles. (C) 2016 The Combustion Institute. Published by Elsevier Inc. All rights reserved.