年間 6 号発行
ISSN 印刷: 2150-766X
ISSN オンライン: 2150-7678
Indexed in
THERMOMECHANICAL ASPECTS OF ENERGETIC CRYSTAL COMBUSTION
要約
The lower thermal conductivity, larger elastic compliance, and greater brittleness of a typical energetic crystal contribute to the importance of thermomechanical influences on combustion and initiation of explosion behavior. For example, recent laser-induced localized heating experiments conducted on RDX and AP crystal surfaces have revealed networks of microscopic cracks in association with the initiation of chemical decomposition. The crystallographically-determined ultrafine crack networks (that have been traced in AP to the orthorhombic to rocksalt structure-type phase transformation as well) are associated, in turn, with the greater hardnesses of energetic crystals. The coupled hardness and brittleness properties are attributed to the difficulty of initiating viscoplastic flow by dislocation movement, as illustrated on a hardness stress-strain basis. In this respect, recent results obtained here that show comparable hardnesses of ADN and RDX crystals are in agreement with a report of comparable drop-weight impact sensitivities. A dislocation pile-up avalanche explanation of such drop-weight impact sensitivity measurements is related to model calculations of thermally induced explosive decompositions. The dependence of impact sensitivity on crystal size is of special interest because of the possibility of relation to crystal size effects that are reported for the pressure dependencies of burning rates.