Alcohol-thermal synthesis of approximately core-shell structured Al@CuO nanothermite with improved heat-release and combustion characteristics

Abstract

Metastable intermolecular composites (MICs), also called nanothermites, are attracting wide attention mainly due to the increased interfacial contact area of the fuels and oxidants therein. In this study, an alcohol-thermal technique is adopted to synthesize approximately core-shell structured Al@CuO MICs, in which process copper acetate is used as the precursor of CuO while Al powder with a wide size distribution (50 nm−5 µm in diameter) is used as cores. The energy-release characteristics of the materials are studied by performing thermal analysis, constant-volume combustion cell tests, and high-speed camera imaging of the combustion process. The results show that Al nanoparticles are surrounded by CuO nanoparticles that are with an average diameter of about 10 nm, while micron-sized Al particles are coated by a continuous layer of nanoplatelets that are assembled from CuO nanoparticles. Benefiting from the enhanced interfacial contact compared with that of ultrasonically mixed counterpart, Al@CuO shows a lower apparent activation energy of solid-state interfacial reaction, a higher light intensity, a shorter burning time, a larger pressure output, and a higher pressurization rate. It is also found that equivalent ratio has a great effect on the combustion process, and a slightly fuel-rich formulation is preferred in this study. The synthesis method developed in this study may also be adapted to the preparation of other core-shell structured MICs.