Deposition and characterization of energetic thin films

Abstract

A new approach for depositing thin energetic films is introduced using doctor blade casting. Magnesium (Mg) and manganese dioxide (MnO2) is mixed with a solvent that includes a binder and is blade cast onto a foil substrate. This study investigated the effect of binder chemistry and concentration on combustion behavior. The Mg–MnO2 system was studied in the following binder–solvent systems: Polyvinylidene Fluoride (PVDF) – Methyl Pyrrolidone (NMP); Viton® fluoroelastomer (Viton A) – acetone; and, paraffin–xylene. Films were cast onto substrates to approximately 100μm thickness. Calorific output and flame velocity were measured for varying binder concentration. Calorific output increased with increasing binder concentration, to a maximum of 4.0kJ/g, suggesting participation of the binder in the exothermic reaction. Flame velocity decreased with increasing binder concentration, with a maximum of 0.14m/s. Binders are less conductive than metals and metal oxides thereby hindering the energy propagation with increasing binder content. Confined flame propagation tests were also conducted for the NMP/Mg–MnO2–PVDF system, with a maximum recorded flame velocity of 3.5m/s. High velocity imaging shows considerable differences in flame front, which may suggest a transition in propagation mechanism accounting for the observed increase in flame velocity.