Formation of composite fuels by coating aluminum powder with a cobalt nanocatalyst: Enhanced heat release and catalytic performance

Abstract Aluminum (Al) and Cobalt (Co) materials are used as a metal fuel and a burning rate catalyst in solid propellants, respectively. However, micro-sized Al fuel has a poor heat release performance because of inertial surface oxide layers, and a nano-sized Co catalyst tends to agglomerate due to high surface energy and magnetism. In this work, we successfully synthesize a new composite fuel by coating Al fuel with a Co catalyst (Co/Al) via a novel replacement reaction and experimentally investigate its heat release and catalytic performance. Our measurements show that the heat release efficiency of Al powder is greatly enhanced by coating only 4.6 wt% of Co. The high oxidation temperature of the formed composite fuel is advanced by 112 °C, and the heat release is approximately 1.5 times that of the raw Al. The Co/Al composite fuel displays excellent catalytic activity and stability toward the thermal decomposition of ammonium perchlorate (AP), thereby decreasing the high decomposition temperature of AP by approximately 150 °C. To the best of our knowledge, the promoting efficiencies of the high-temperature oxidation of Al and the high-temperature decomposition of AP are higher than those reported in literature. The heat release and catalytic thermal decomposition mechanisms of Co/Al composite fuel are proposed on the basis of experimental phenomena and results. Results confirm that the formation of composite fuel by coating Al powder with a Co nanocatalyst is an effective method to enhance the heat release of Al and the catalytic performance towards AP. The as-obtained Co/Al composite fuel is expected to have wide application prospects in solid propellants.