SHOCK-INDUCED REACTIONS IN CYLINDRICAL CHARGES OF TITANIUM-SILICON POWDER MIXTURES

Although reaction can be initiated by shockwaves in titanium and silicon powder mixtures, self-sustained reactive waves have mainly been observed in a deflagration mode propagating on the order of a few centimeters per second. In the present work, the possibility of faster combustion modes is investigated by observing the propagation of reactive waves in cylindrical charges up to fifteen diameters long. Fine powders below 45 mum in size are mixed and packed into cylindrical containers made of various materials thus providing varying degrees of confinement. The mixture porosity was varied between 47% and 65%. After initiation by a high explosive booster charge, reactive waves were observed using optical and piezoelectric time-of-arrival gauges. Rapid reactive waves were observed to propagate at about 2 km/s, then die out after a distance of about two charge diameters. The extended length of propagation of these waves points to a contribution of chemical energy from the powder reaction.