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Keywords = Zirconium Potassium Perchlorate (ZPP)

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7 pages, 1257 KiB  
Article
Thermodynamic Analysis on the Aging of THPP, ZPP and BKNO3 Explosive Charges in PMDs
by Kyung Min Kim, Sung Il Choi, Ki Heon Eom, Gil Hwan Ahn, Jong Gyu Paik, Byung Tae Ryu, Yong Ha Kim and Yong Sun Won
Energies 2019, 12(2), 209; https://doi.org/10.3390/en12020209 - 10 Jan 2019
Cited by 9 | Viewed by 5538
Abstract
The aging of explosive charges in pyrotechnic mechanical devices (PMDs) significantly affects the reliability of their performance. Aging decreases the explosive power of explosive charges via pre-oxidation by external sources of oxygen. In this study, the flame temperature was calculated based on the [...] Read more.
The aging of explosive charges in pyrotechnic mechanical devices (PMDs) significantly affects the reliability of their performance. Aging decreases the explosive power of explosive charges via pre-oxidation by external sources of oxygen. In this study, the flame temperature was calculated based on the amount of added oxygen source, and the effect of aging was quantified in terms of the performance of explosive charges. Three primary explosive charges (THPP, ZPP, and BKNO3) were selected, and the explosion was assumed to have occurred in a closed adiabatic system. The flame temperature decreased with increasing oxygen addition, suggesting that the aging decreased the pressure exerted by the PMDs. The explosive power decreased in the following order: ZPP >> THPP > BKNO3 (4100 >> 3260 > 3050 K), and it was decreased by aging as follows: ZPP >> BKNO3 > THPP (802 >> 219 > 95 K per mole of added water). As a result, ZPP is appropriate for the generation of the huge thrust of PMDs despite its increased susceptibility to aging, while THPP is superior for reliable PMD performance. Full article
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7 pages, 1654 KiB  
Article
A Combined Study of TEM-EDS/XPS and Molecular Modeling on the Aging of THPP, ZPP, and BKNO3 Explosive Charges in PMDs under Accelerated Aging Conditions
by Kyung Min Kim, Junwoo Lee, Sung Il Choi, Gil Hwan Ahn, Jong Gyu Paik, Byung Tae Ryu, Yong Ha Kim and Yong Sun Won
Energies 2019, 12(1), 151; https://doi.org/10.3390/en12010151 - 2 Jan 2019
Cited by 3 | Viewed by 4124
Abstract
The aging mechanism of explosive charges in pyrotechnic mechanical devices (PMDs) is pre-oxidations of their fuels (TiH2 for THPP, Zr for ZPP, and B for BKNO3) by external oxygen. The effect of water on the aging of explosive charges was [...] Read more.
The aging mechanism of explosive charges in pyrotechnic mechanical devices (PMDs) is pre-oxidations of their fuels (TiH2 for THPP, Zr for ZPP, and B for BKNO3) by external oxygen. The effect of water on the aging of explosive charges was thus investigated by TEM-EDS/XPS and DFT-based molecular modeling under accelerated aging with 71 °C and 100% relative humidity. The formation of oxide shell and its thickness on the surface of fuels by the aging were observed by TEM-EDS. It failed to detect any oxide on the surface of TiH2 (no sign of Ti-O peaks in XPS) regardless of the aging time, while the thickness of oxide shell increases linearly with the time for ZPP and is saturated at a certain point for BKNO3. It suggested that THPP is highly robust to aging compared to the others (the order of THPP >> BKNO3 > ZPP). Then, DFT-based vacuum slab calculations visualized the diffusion of oxygen from the surface of fuels into the interior, confirming that the activation barrier for the oxygen diffusion is much lower for Zr and B than TiH2 (37, 107, and 512 kcal/mol for Zr, B, and TiH2, respectively), in agreement with experimental results. Full article
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