Low-temperature ignition and mechanism of μAl coated with bismuth citrate

Because of the existence of an oxide layer on the surface of micron aluminum (μAl) powder, it is difficult to ignite. In order to improve μAl ignition, Al particles were coated with bismuth citrate (Bi(cit)) by a solvent evaporation method. The morphology of Al-Bi(cit) was observed by scanning electron microscope (SEM) showed that Bi(cit) was evenly distributed on the surface of Al particles. The ignition temperature was reduced and ignition delay time at different temperatures of the Al-Bi(cit) were tested in a transparent tube furnace. With the increase of Bi(cit) content, the ignition temperature and ignition delay time shortened, and the combustion flame captured by the high-speed camera was more bright. The test results showed that Al-20 wt% Bi(cit) has a low ignition temperature of 479 °C, and the ignition delay time at 450 °C is only 7 s. The thermal behavior of Al-Bi(cit) was studied by thermogravimetric analysis (TG-DSC). Combined with the characterization results of the products at different heating temperatures, the combustion mechanism was proposed and proved.