Self-Propagating Reactive Fronts in Compacts of Multilayered Particles

• Published in: Journal of nanomaterials 2013-01, Vol.2013 (2013), p.1-11
• Main Authors: Weihs, Timothy P., Alawieh, Leen, Vohra, Manav, Sraj, Ihab, Knio, Omar M.
• Format: Article
• Language: English
• Subjects: Compacts; Computer simulation; Contact; Foils; Mathematical models; Quantitative analysis; Thermal resistance; Thin films
• ISSN: 1687-4110; 1687-4129
• DOI: 10.1155/2013/198096

Reactive multilayered foils in the form of thin films have gained interest in various applications such as joining, welding, and ignition. Typically, thin film multilayers support self-propagating reaction fronts with speeds ranging from 1 to 20 m/s. In some applications, however, reaction fronts with much smaller velocities are required. This recently motivated Fritz et al. (2011) to fabricate compacts of regular sized/shaped multilayered particles and demonstrate self-sustained reaction fronts having much smaller velocities than thin films with similar layering. In this work, we develop a simplified numerical model to simulate the self-propagation of reactive fronts in an idealized compact, comprising identical Ni/Al multilayered particles in thermal contact. The evolution of the reaction in the compact is simulated using a two-dimensional transient model, based on a reduced description of mixing, heat release, and thermal transport. Computed results reveal that an advancing reaction front can be substantially delayed as it crosses from one particle to a neighboring particle, which results in a reduced mean propagation velocity. A quantitative analysis is thus conducted on the dependence of these phenomena on the contact area between the particles, the thermal contact resistance, and the arrangement of the multilayered particles.