Modeling and simulation of self-propagating exothermic reactions in Al/Ni reactive multilayer films and experimental validation

This paper reports the simulation and experimental validation of a MEMS (micro-electro-mechanical systems)based Al/Ni reactive multilayer films (RMFs). A finite element model of a double V-shaped Al/Ni reactive multilayer films was developed by combining a thermoelectric coupling model with a self-propagating exothermic reaction model. The results show that the reactive multilayer films with a modulation ratio of 3:2 reach the energy peak the fastest under the same voltage excitation, which suggests that the modulation ratio determines the energy level of the reactive multilayer films before 20 mu s, thus affects the energy output of the whole ignition process. Al/Ni reactive multilayer films with different modulation ratios were prepared using electron beam evaporation, the results of the ignition experiments showed that the reactive multilayer films with a modulation ratio of 3:2 had larger flames, which agreed with the simulated results. This suggests that calculating the enthalpy changes process of reactive multilayer films by coupling the self-increasing exothermic reaction can be used to analyze the chemical reaction process of the reactive multilayer films at any moment prior to 20 mu s and to predict the flame size to some extent. This approach can be extended to other ignition prediction applications for MEMS-based ignitors.