(70cp) Investigation on Dry-Mixing of Sub-Micron Sized B and Bacro4 Particles

The objective of this investigation is to improve the mixture homogeneity of Boron and Barium Chromate (T-10 delay composition used by Navy) using a novel dry mixing technique. The intent is to develop a new environmentally dry mixing process which will improve homogenous mixture and eliminate downstream processing (drying) time associated with the current conventional mixing used for T-10. Three different mixing methods were used; the magnetically assisted impaction mixing (MAIM, a dry mixing process); solvent-based mixing coupled with ultrasonic agitation and hand shaking mixing. The solvent based mixing process serves as an investigative reference point for the mixing effectiveness of the current conventional mixing processes used to mix T-10. The combination of the different mixing methods, mixing parameters and their associated processes, allow for comparative analysis of the homogeneity of the resulting mixtures. For characterization, the as-received powders of the two components and the mixtures were investigated in an FE-SEM equipped with an EsB detector which provides higher Z contrast at extremely low accelerating voltage, resulting in higher spatial resolution, a 200 kV EF-TEM with EELS, and other systems such as Particle Size Analyzer (LS-230). FESEM is suitable for characterizing powder mixtures having a distinct difference in particle size and shape, or with a significant difference in atomic order of the elements. The results suggest that the MAIM method produce the most homogeneous mixture of the three mixing methods resulting in an homogeneous mixtures with significant reduction in agglomerate size through out the mixture while offering increased savings in processing time, elimination of segregation during drying as drying is not required, and environmental friendly process and the capability for easy scale up. The mixtures produced using the dry and wet methods are further analyzed through actual burning tests. The focus of this invetsigation is to measure and evaluate the combustion propagation of T-10 mixtures for a Dry and a Wet mixing process. The objective is to provide comparative burn rate performance for both the Dry (MAIM) and Wet mixing processes, and evaluate these results relative to a maximum allotted variation for the burn rates. The burn rate tests results show that the MAIM mixing provides as good or better performance than the wet mixing.