The robustness of titanium hydride potassium perchlorate (THPP) for long-term stability of pyrotechnic mechanical devices (PMDs)

摘要

Long-term stability of the explosive charges in pyrotechnic mechanical devices (PMDs) is important in order to sustain the precision and accuracy of the explosion. We have been seeking robust materials against aging since self-generated aging by internal factors and induced aging by external factors, such as humidity (or extra oxygen source), might cause physical or chemical changes of the explosive charges to reduce their explosive power (or performance degradation). In this study, we precisely analyzed the aging properties of titanium hydride potassium perchlorate (THPP), one of the primary explosive charges. For the self-generated aging by internal factors, AKTS (advanced kinetics and technology solution) simulation using DSC (differential scanning calorimeter) profiles of different heating rates (1, 2, 4 and 8 degrees C/min) were used to calculate the initiation time of spontaneous reaction. The resulting initiation time at a storage temperature of 192 degrees C was 200 years, demonstrating that THPP is hardly aged by itself. To investigate the induced aging by humidity, THPP samples aged under 100% RH (relative humidity) at 70 degrees C up to 16 weeks were characterized. Thermal analysis showed no loss of relative heat released (or no loss of explosive power) by the aging time, and almost constant reaction rate was maintained, indicating THPP is not affected by aging both thermodynamically and kinetically. This result was confirmed by direct TEM (transmittance electron microscope)-EDS (energy dispersion spectroscopy) observations as well, where no trace of oxide on the surface of titanium hydride (TiH2) appeared regardless of the aging time.