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491d

Effect of Mechanical Activation on Reaction Kinetics In Gasless Heterogeneous Systems

Jeremiah D.E. White and Alexander S. Mukasyan. Department of Chemical and Biomolecular Engineering, University of Notre Dame du Lac, 182 Fitzpatrick Hall, Notre Dame, IN 46556

In this work, we investigated the effects of mechanical activation (MA) on the kinetics of several gasless reaction systems, including nickel-aluminum, hafnium-aluminum, iron oxide--titanium, and others. Reaction kinetics were primarily studied by differential thermal analysis (DTA), while the microstructures of the investigated reaction mixtures were characterized by scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), and x-ray diffraction analyses (XRD). It was demonstrated that under certain conditions, MA can significantly (>10 times) change the activation energy in such gasless high energy systems. This effect, in turn, influences the self-ignition temperature, as well as the velocity of the reaction wave propagation in these systems. Based on established correlations between the kinetic parameters and microstructural characteristics of heterogeneous reaction media, an explanation of the observed effect is suggested.