Reactive Fragmentation and Energy Conversion in Ballistic Impact of Structural Reactive Materials

The main goal of a structural reactive material (SRM) is to produce appreciable chemical potential energy on demand while additionally providing structural integrity to the application. While SRMs are a relatively new class of energetic composites, recent advances in diagnostics and analysis techniques present opportunities to examine energy partitioning from a SRM upon high velocity impact, fragmentation, and reaction. This study analyzes partitioning chemical energy into gas and condensed phase energies as a function of the solid oxidizer concentration within the SRM projectile and the oxygen concentration in the gas environment. Projectiles were made by consolidating aluminum (Al) with varied concentrations of molybdenum trioxide (MoO₃) powders, and ballistic impact experiments were performed in air and inert argon environments. The SRM projectiles were launched at 1050 m/s into two different chambers. Pressure measurements were made in a semi-sealed calorimetric chamber to quantify gas phase energy conversion and thermography measurements were made using a visual chamber to quantify condensed phase energy conversion. The results show increasing MoO₃ concentration promotes gas energy conversion in an air environment. The opposite was observed in argon, increasing MoO₃ concentration promotes condensed phase energy conversion. Processes responsible for controlling energy partitioning are discussed.