Pseudo-oxide metal carbodiimides: Application in thermite reactions

Well-known thermite reactions, which are strong exothermic reactions typically between a metal and an oxide, offer diverse important applications, such as the synthesis and processing of materials, detonators, and propulsion. A fascinating family of nitrogen-containing analog solid-state metal carbodiimides, with the general formula M x (NCN) y considered to be pseudo-chalcogenide or even pseudo-oxide, have drawn much attention owing to their unique physico-chemical properties. Herein, metal carbodiimides such as CuNCN are investigated as novel oxidizers for thermite reactions. We studied the Al/CuNCN thermite reaction, including thermal transformation, energy release and combustion performance, by means of complementary techniques, such as thermogravimetric-mass spectrometry (TGA-MS), differential scanning calorimetry (DSC), pressure evolution measurements and high-speed cameras. Compared to conventional Al/CuO thermite, the novel Al/CuNCN thermite system not only exhibited a strong combustion phenomenon with large energy release but also generated gases such as N 2 and (CN) 2 . Additionally, the burning flame of Al/CuNCN presented a mushroom-cloud shape and was accompanied by a large number of hot spots due to the unique combustion characteristics of blasting and gas production. Even more encouraging was that the Al/CuNCN system was able to prepare AlN materials following a self-propagating route within one second. This work sheds light on the novel application of CuNCN in thermite reactions and potential routes to prepare gas generator and AlN.(c) 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.