Solution combustion synthesis of metal nanopowders: Copper and copper/nickel alloys



Based on a general methodology for the preparation of metal–nanopowders by solution combustion synthesis (SCS), the reaction pathways for SCS of pure copper and copper–nickel alloy nanopowders are investigated. It is confirmed that the necessary condition for SCS of metals in a metal-nitrate oxidizer–glycine system is the property of the oxidizer to decompose with formation of HNO3 species. In this case, for compositions with excess of glycine, a hydrogen reducing atmosphere develops in the reaction front, leading to the formation of reduced metals. The proposed reaction pathways are supported by X-ray diffraction analysis of the quenched samples and DTA–TGA studies of the Cu(NO3)2·6H2O–glycine and Ni(NO3)2·6H2O/Cu(NO3)2·6H2O–glycine systems. The results show that the formation of Cu2O and CuO oxide phases takes place at early stages in the reaction front followed by their reduction to pure Cu phase in the postcombustion zones. However, in a Cu–Ni alloy, a fraction of intermetallic Cu–Ni phase appeared directly in the combustion front, whereas the rest of the oxygen-free alloy formed through reduction of oxide phases. © 2011 American Institute of Chemical Engineers AIChE J, 2011