A review on combustion synthesis intensification by means of microwave energy

Combustion synthesis (CS) is a materials manufacturing technique, which gained increased attention by both academia and industries, due to its intrinsic energy saving characteristics and high purity of the products. Energy requirements for CS are limited to the ignition step, since the desired products are obtained by using the heat generated by exothermic reactions occurring between the reactants. CS has been here addressed from a process intensification perspective, since CS characteristics perfectly fit into several process intensification definitions, aims and approaches. Particular attention has been dedicated to the use of microwaves as energy source for CS, and the benefits deriving from the combination of these two techniques have been reviewed. The doubtless better energy transfer efficiency of microwaves, with respect to conventional heating techniques, arising from the direct interaction of the electromagnetic energy with the reactants, contributes to further intensify both solid state and solution CS processes. Moreover, microwaves peculiarities, such as their selective and volumetric nature, together with their energy transfer nature, open new attractive opportunities for CS in different fields of materials science, like joining and advanced protective coatings. Innovative strategies of microwaves-ignited and/or sustained CS for the process intensification of advanced materials manufacturing are proposed as well. (C) 2013 Elsevier B.V. All rights reserved.