3. Nanostructured Energetic Composites: An Emerging Paradigm

Nanotechnology has ushered a remarkable progress in the field of medicine, environment, ceramics, especially considering its applications in the defence sector. This progress has been inspired by the ordered assembly of molecular and nanoscale elements to develop multifunctional smart reactive materials for energetic applications. An important class of these materials is the nano-energetic materials or nanothermites, which are composed of nanometals and nano-oxidizers. A major drawback of classical micron-sized metal particles is that they ignite after a comparatively long delay. These micron-sized metal particles when combined with oxidizer such as metal oxides as in thermite result in metal delays which are usually associated with diffusion of oxidizer and/or fuel through the protective layer of metal oxides. The motive behind nano-energetic materials is to develop a new synthetic procedure, which could limit both the oxidizer and the fuel balance in the thermites. Development of assembly of energetic composite materials (by number of techniques like self-assembly, cold spraying, ball milling, sol–gel, gas-phase processes) is touching new horizons of research. In this chapter, emphasis is laid on the current research focusing on manipulation of individual atoms and molecules to produce organized and systematic structure of nanocomposites for applications in nanothermites. Nanothermites are comparatively a new class of energetic material that consist of metallic fuel and metal oxide-based oxidizer with critical dimensions on the nanoscale. The standard powder-mixing protocol has intrinsic constraints, particularly random distribution of fuel and oxidizer particles and unavoidable fuel pre-oxidation. The present research scenario deals with an alternative approach for nanostructured energetic composites by varied processes. The subsequent sections of this chapter will meticulously describe the strategies adopted for the preparation of such nanostructure assemblies. These hierarchical structures provide desirable performance in combustion, ignition and mechanical characteristics. In the end, some promising applications of nanostructured energetic composites incorporated into various systems ranging from microelectromechanical systems (MEMS) devices to rocket propellants to explosives that permit new functions to be performed are illustrated.