Investigation of the Origin of Hot Spots in Deformed Crystals: Final Report onAmmonium Perchlorate Studies

摘要

A number of single crystals of ammonium perchlorate (A-P) were shock loaded nearthe reaction threshold to investigate the effects of concentrated lattice defects (dislocations) and differing crystal orientations on chemical reactivity. Large, optical quality crystals of pure AP were immersed in mineral oil and shocked through either the (001) or 210 surfaces by a detonator. Prior to shock loading, some crystals had localized regions of increased lattice defects and strain created by placing diamond pyramid (Vickers) hardness impressions into their exterior cleavage surfaces. High-speed photographs showed preferential cracking and luminosity near some of the hardness impressions. The photographs also revealed the occurrence of the same slip deformation identified previously from hardness testing. The shocked crystals were recovered, sometimes intact, for microstructural characterization and chemical analyses. Crystal orientation relative to the shock propagation direction changed the dynamic response and threshold for decomposition of the crystal, indicating the influence of material microstructure. Along these freshly cleaved surfaces, the XPS results showed enhanced lattice disruption and perchlorate decomposition as a result of the hardness impressions. The greatest decomposition was not immediately adjacent to the impressions, but near the tips of cracks and along slip planes emanating from the impressions several millimeters, or more, into the crystal.... Ammonium perchlorate, X-ray Photoelectron spectroscopy, Hot spot, Dislocation density, Microhardness, Shock reactivity.