Abstract and subjects
In an effort to better understand the evolution of sensitivity in HMX-based explosives formulations during the reversion from the delta to the beta polymorph, we have performed friction and impact experiments on Class 1 (coarse) and Class 2 (fine) HMX [1]. Initial baselines for Type 12 drop weight impact and BAM friction sensitivities were obtained for the beta-HMX starting material. The HMX was then heated at similar to 184 C,for 14 h. Raman spectroscopy was used to confirm the conversion to delta-phase. Raman results show that the delta material remains delta for long periods when stored in a dessicator at room temperature (RT), converts to alpha when stored at RT and 20-40% relative humidity (RH) over a period of days, and reverts to beta over a period of days when stored at RT and 95-98% relative humidity (RE). Impact and friction tests were performed on the delta-HMX, converted alpha-HMX, and reverted beta-HMX. The tests show similar sensitivities of the delta-HNEX and converted alpha-HMX in both impact and friction, both of which are similar to 10-20% more sensitive than the beta-HMX and reverted beta depending on the particle size distribution. The alpha-HMX appears to be fairly stable over time (by Raman analysis) at ambient conditions, but fairly low humidity (20-40%), or in a dessicator.