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- Title
Mn+Sb<sub>2</sub>O<sub>3</sub> Thermite/Intermetallic Delay Compositions.
- Authors
Montgomery, Yolandi C.; Focke, Walter W.; Atanasova, Maria; Del Fabbro, Olinto; Kelly, Cheryl
- Abstract
The binary Mn+Sb2O3 pyrotechnic composition was investigated for mining detonator time delay applications. EKVI thermodynamic modelling predicted two maxima in the adiabatic reaction temperature. The local maximum, at a manganese fuel content of ca. 36 wt-%, corresponds to a pure thermite-type redox reaction: 3 Mn+Sb2O3→3 MnO+2Sb. The overall maximum in the adiabatic reaction temperature (ca. 1640 K), at the fuel-rich composition of 49 wt-% Mn, is consistent with the reaction 5 Mn+Sb2O3→3 MnO+2 MnSb, i.e. a combination of the standard thermite with an additional exothermic intermetallic reaction. XRD analysis of combustion residues confirmed the formation of MnSb and Mn2Sb for fuel-rich compositions. Burn rates were measured using delay elements assembled into commercial detonators. The d50 particle sizes were 23.4 and 0.92 μm for the Mn fuel and Sb2O3 oxidant powders, respectively. The delay elements comprised rolled lead tubes with a length of 44 mm and an outer diameter of 6.4 mm. The rolling action compacted the pyrotechnic compositions to 74 ± 2 % theoretical maximum density. The burning rate increased linearly from 4.2 to 9.4 mm s−1 over the composition range 25-50 wt-% Mn.
- Subjects
INTERMETALLIC compounds; TIME delay estimation; ARRHENIUS equation; THERMAL properties
- Publication
Propellants, Explosives, Pyrotechnics, 2016, Vol 41, Issue 5, p919
- ISSN
0721-3115
- Publication type
Article
- DOI
10.1002/prep.201600007