Use of thin-film samples to study thermal decomposition chemistry of explosives.

摘要

Development of reliable models for design, performance, stability, and hazard analyses of energetic materials requires detailed understanding of three principal chemical reaction regimes: initial condensed-phase decomposition, subsequent interaction of decomposition products with the remaining condensed phase, and gas- phase reaction of decomposition products to form the ultimate combustion products. The initial condensed-phase decomposition has been particularly difficult to study, due to the inability to probe directly chemistry in the condensed phase under isothermal conditions and with the spatial and temporal resolution needed at high temperatures and reaction rates. Thin-film samples provide a means to study condensed-phase chemistry at isothermal conditions and with microsecond temporal resolution. This paper describes results from experiments in which thin-film samples nd multiple diagnostics are used to examine condensed-phase chemistry and monitor evolved gas species from explosives such as RDX, HMX, TATB. Sample heating rates, reaction temperatures, and reaction times varied from about 10(sup 8) to less that 1(degree)C/s, from ambient to about 500(degree)C, and from about 10(sup (minus)3) to greater that 10(sup 5) seconds, respectively. Conventional infrared spectroscopy and time-resolved infrared spectral photography were used to detect condensed-phase decomposition products. Mass spectrometry, using both time-of-flight and quadrupole mass spectrometers, was used to monitor evolved gas species. Results from these experiments have been encouraging. For example, conventional infrared spectra from totally confined samples of RDX that were thermally aged at 170(degree)C, for 18 hours, indicated condensed-phase formation of H(sub 2)O and HCN.