Rod Russell

Impact-Driven Thermite Reactions with Iodine Pentoxide and Silver Oxide

Thermite reactions using aluminum (Al) fuel and either iodine pentoxide (I2O5) or silver oxide (Ag2O) were initiated by high-velocity impact or thermal initiation and examined for their flame propagation behavior. In the impact-ignition experiments, the Al-Ag2O reaction produced more energy than the Al-I2O5 reaction; in the thermal-ignition experiments, the I2O5 reaction produced higher flame propagation rates (1,305 m/s compared with 531 m/s). The energy released from impact-initiated reactions is significantly enhanced by reducing the size of the oxide particles. Results suggest that the reaction propagation mechanisms may be the same, even though ignition is spurred by two different stimuli (mechanically induced compaction versus thermal).

Dynamic high-strain-rate mechanical behavior of microstructurally biased two-phase TIB2+AL2O3 ceramics

The dynamic high-strain-rate behavior of two-phase TiB2+Al2O3 ceramics with biased microstructures was investigated in this study. The microstructural bias includes differences in phase (grain) size and phase distribution such that in one case a continuous (interconnected) TiB2 network surrounds the Al2O3 phase (qualitatively termed “T@A”) and in another case the TiB2 and Al2O3 phases are interdispersed and uniformly intertwined with each other (qualitatively termed “TinA”). Quantitative microscopy was used to characterize the phase size and the integral curvature which is taken as a measure of TiB2 phase connectivity around Al2O3. Dynamic compression and tension (spall) properties were measured using plate impact experiments. The measurements used piezoelectric polyvinyldine fluoride stress gauges to obtain the loading profile and to determine the Hugoniot elastic limit. In addition, velocity interferometry system for any reflector interferometry was used to obtain the spall signal and the tensile dynami...

Sporicidal effects of iodine-oxide thermite reaction products

Iodine pentoxide-aluminum thermite reactions have been driven by impacts at 1000 m/s on steel plates 3 mm or thicker. This reaction releases iodine gas that is known to be a sporicide. To test the impact reactions for sporicidal effects, reactions took place in closed chambers containing dried Bacillus subtilis spores. The reduction in colony-forming units was dependent on the exposure time; long exposure times resulted in a 105 decrease in germination rate. This was shown to be due to the gas exposure rather than the heat or turbulence. Sporicidal effectiveness was increased by adding neodymium and saran resin.

DAMAGE EVOLUTION IN BALLISTIC IMPACT OF GLASS PLATES

High‐velocity impact onto a layered glass target produces a very extensive damage pattern exhibiting many distinct morphologies. High‐speed photography reveals failure waves and cracks that move at acoustic velocities. These prompt features evolve into a complex final damage pattern that includes needle fragments around the penetration cavity, radial cracks at mid distance, and dicing cracks near the edges.

Impact Induced Failure Zones in Homalite Bars

Impact tests were conducted on Homalite bars. Bars were impacted at 250 m/s with various flyer plates. Bar behavior was observed with a high‐speed digital camera. Homalite bars exhibited repeatable failure modalities with little effective change coming from flyer plate or bar geometry. Failure is characterized by early, late, and intermediate morphologies. Early failure exhibits a radial damage cone near the impact event. Late damage adds a catastrophic failure zone near the bar end and multiple wave front locations along the length of the bar. Intermediate time pictures indicate that catastrophic failure starts as a series of spall‐like planes in the catastrophic failure zone.