Potassium fluoride improving the ignition and combustion performance of micron-sized aluminum particles in high temperature water vapor

Abstract

ABSTRACT To improve the ignition and combustion characteristics and combustion efficiency of micron-sized aluminum particle in high temperature water vapor atmosphere, a self-designed tube furnace setup was used to study the effects of potassium fluoride (KF) on the ignition and combustion characteristics of micron-sized aluminum particle in high temperature water vapor. The ignition and combustion processes, components and morphologies of combustion products, and combustion efficiency were recorded and analyzed by a high-speed photographic system, X-ray diffraction, scanning electron microscopy with energy-dispersive spectrometer, and chemical analysis method, respectively. Results show that the addition of KF to 5 μm aluminum powder significantly decreases its ignition delay time because the hydrolysis of KF generates KOH in water vapor, and KOH corrodes the oxide shell on the aluminum surface to promote the reaction of aluminum with water, which can be proved by the morphologies of the products. The hydrolysis product of KF can destroy the oxidation shell on the aluminum powder surface, but it does not cause the aluminum particles to undergo shell-breaking combustion. As the KF content increases, the oxide shell is dramatically destroyed, so the ignition delay time of aluminum powder in high temperature water vapor decreases. Moreover, the combustion efficiency of aluminum powder with addition of KF increases considerably with increasing of the KF content.