Mechanical and thermophysical properties of energetic crystals: evaluation methods and recent achievements

The mechanical properties of energetic crystals (ECs) are relevant to the safety and performance of ammunitions and propellants. Several experimental and theoretical investigations have been conducted on different ECs to study their mechanical properties and effects on sensitivity and stability. Using evaluation methods such as nanoindentation, Raman spectroscopy, and molecular dynamic simulations, a significant amount of helpful information on this topic has emerged, some of which are summarized herein. The overall safety and performance of energetic materials depend on the properties of the energetic crystalline ingredients. Properties such as the thermostability and sensitivity of such crystals have been greatly improved using methods such as cocrystallization, recrystallization, coating, and intercalation. The overall strength and, thus, the safety of formulations largely depend on the quality and mechanical strength of included ECs. Therefore, it is essential to investigate the mechanical strengths of the modified ECs. This review also summarizes various theoretical and experimental methods to study the mechanical properties of pure ECs. As a proposal, additional research on the mechanical strength of modified hybrid ECs with improved energy density and sensitivity is necessary to ascribe the inherent mechanisms.