The effects of additives on the combustion characteristics of aluminum powder in steam

Abstract

To develop the combustion characteristics of aluminum powder in steam, the ignition and combustion process of aluminum powder with different additives (KBH₄, ammonium perchlorate (AP) and NaCl) addition at different levels were studied using a transparent pipe furnace. The temperature variation of these samples was measured using a thermocouple, and a high-speed camera was used to record combustion phenomenon. The solid combustion products of these samples with good characteristics were collected to analyze the microstructure and component. The results indicate that the ignition temperature of aluminum powder is decreased by adding these additives or increasing the content of the additive, whereas the maximum combustion temperature is different. When adding 3 wt% KBH₄, the maximum combustion temperature reaches up to 1404 °C, which is higher than that of the original aluminum powder. However, upon addition of AP or NaCl the maximum combustion temperature decreases. Simultaneously, the combustion flame of aluminum powder with addition of KBH₄ or AP is comparatively intense and bright, whereas the addition of NaCl reduces combustion intensity. The different influence mechanisms of additives on the ignition and combustion of aluminum powder are believed to be responsible for the experimental results.