Reaction kinetics study of Al-Fe2O3 nanoenergetics
Date of Issue2012
School of Materials Science and Engineering
Advanced Technology Research Centre
This thesis investigates the various important parameters such as oxidizers’ morphology, size, equivalence ratio and synthetic methods which affect reactivity of Al-Fe2O3 nanoenergetics. Parametric studies conducted in this study are correlated with proposed reaction routes and derived reaction kinetics (Ea values) giving an overall understanding in the reactivity of nanoenergetics performance. Morphological effects of Fe2O3 oxidisers were found to be of greatinfluence in affecting nanoenergetics’ reactivity which has yet been studied. Nanotubular Fe2O3 oxidisers + Al nanoparticles system was found to be the most reactive and the reaction route (post-thermal studies on reacted products) that facilitates this enhanced performance was proposed. A new phenomenon of nanotubular oxidizers in possible generation of “hotspots” was also observed using microscopy imaging of reacted products at respective temperature intervals. The expected higher reactivity of the nanothermites compared to micron thermites was consistent with studies made by various groups in the energetic community. In addition, new findings in the preferred reaction route taken by the nanothermite in enhancing reactivity were found. The reactivity of Al- Fe2O3 was found to be highly dependent on the equivalence ratio. An increase in maximum pressure output (Pmax), time to reach max pressure (tmax) and rate of pressure released (dP/dt) were observed with increased ratio due to better thermal conductivity and energy content in fuel rich compositions, but with a delayed reaction.Solvent mixed and surfactant assembled Fe2O3 nantubes + Al nanoparticles were compared in terms of homogeneity of mixing in influencing reactivity. A new and novel assembling method was developed in this study using APTES (aminopropyltriethoxy silane) and carboxylic acid groups as molecular attracting ligands. This highly selective assembly technique was found to have higher reactivity compared to surfactant assembled system possibly due to shorter molecular linkers in reducing the overall diffusion length.