AN EXPERIMENTAL-STUDY OF THE DEFLAGRATION-TO-DETONATION TRANSITION INGRANULAR SECONDARY EXPLOSIVES

The deflagration-to-detonation transition (DDT) has been studied in pr epared columns of granular secondary explosive. The secondary explosiv es 2-(5-cyanotetrazolato) pentammine cobalt (III) perchlorate (CP) and pentaerythritol tetranitrate (PETN) were chosen for the study due to their known propensity to undergo DDT within a few millimetres of igni tion. Confinement of CP columns within polycarbonate and PETN within m etallic confinement fitted with slit windows allowed direct high-speed streak photography of the events. Deflagration and detonation velocit ies and the run-to-detonation lengths were measured as a function of c harge pressed density. Ignition of the explosive column was attained t hermally through a copper barrier with a gasless pyrotechnic. Deflagra tion and detonation velocities were seen to depend strongly upon press ed density with both explosives. There appeared to be a maximum densit y conductive to DDT with both explosives but no minimum with CP. Studi es of DDT continue to have interest for the safe storage and use of re active materials, and for the development of a detonator based on a se condary explosive.