Effects of Shear Rate during Energetic Material Processing on Reactivity

Michael A. Sweeney, K. Ryan Bratton, Connor Woodruff, Colt Cagle, Kevin J. Hill, Michelle L. Pantoya, Gordon F. Christopher

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Energetic materials are often processed at high rates of deformation as colloidal slurries and then cured. The slurries are non-Newtonian colloidal solutions that exhibit changes in microstructure with variations in applied flow. This study shows that changes to microstructure due to applied flow affect the reactivity of energetic thin films. Energetic thin films of identical composition and geometry are prepared with different applied shear rates, which produce variations in the film microstructure by segregating smaller particles toward surfaces. Results show that films exhibit significant gains in flame speed with increasing shear rate. The differences in flame speed are linked to variations in microstructure. Specifically, densification of smaller particles near a boundary promote increased flame speeds. However, when particles become segregated, larger particles tend to contribute less to the overall reaction because they burn slowly compared to the smaller particles. When segregated, the larger particles may not be adding chemical energy to the reaction front because propagation is dominated by the more ignition sensitive smaller particles. This study demonstrates explicit changes in reactivity arising from changes in processing conditions that affect microstructure. Controlling applied shear rate introduces a new approach to regulating energetic material reactivity when processed using extrusion-based advanced manufacturing techniques.

Original languageEnglish
Article number1801324
JournalAdvanced Engineering Materials
Volume21
Issue number5
DOIs
StatePublished - May 2019

Keywords

  • additive manufacturing
  • colloid
  • energetic materials
  • particle microstructure
  • processing
  • random particle media
  • shear rate

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