TY - JOUR
T1 - Activating Aluminum Reactivity with Fluoropolymer Coatings for Improved Energetic Composite Combustion
AU - McCollum, Jena
AU - Pantoya, Michelle L.
AU - Iacono, Scott T.
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/8/26
Y1 - 2015/8/26
N2 - Aluminum (Al) particles are passivated by an aluminum oxide (Al2O3) shell. Energetic blends of nanometer-sized Al particles with liquid perfluorocarbon-based oxidizers such as perfluoropolyethers (PFPE) excite surface exothermic reaction between fluorine and the Al2O3 shell. The surface reaction promotes Al particle reactivity. Many Al-fueled composites use solid oxidizers that induce no Al2O3 surface exothermicity, such as molybdenum trioxide (MoO3) or copper oxide (CuO). This study investigates a perfluorinated polymer additive, PFPE, incorporated to activate Al reactivity in Al-CuO and Al-MoO3. Flame speeds, differential scanning calorimetry (DSC), and quadrupole mass spectrometry (QMS) were performed for varying percentages of PFPE blended with Al/MoO3 or Al/CuO to examine reaction kinetics and combustion performance. X-ray photoelectron spectroscopy (XPS) was performed to identify product species. Results show that the performance of the thermite-PFPE blends is highly dependent on the bond dissociation energy of the metal oxide. Fluorine-Al-based surface reaction with MoO3 produces an increase in reactivity, whereas the blends with CuO show a decline when the PFPE concentration is increased. These results provide new evidence that optimizing Al combustion can be achieved through activating exothermic Al surface reactions. (Figure Presented).
AB - Aluminum (Al) particles are passivated by an aluminum oxide (Al2O3) shell. Energetic blends of nanometer-sized Al particles with liquid perfluorocarbon-based oxidizers such as perfluoropolyethers (PFPE) excite surface exothermic reaction between fluorine and the Al2O3 shell. The surface reaction promotes Al particle reactivity. Many Al-fueled composites use solid oxidizers that induce no Al2O3 surface exothermicity, such as molybdenum trioxide (MoO3) or copper oxide (CuO). This study investigates a perfluorinated polymer additive, PFPE, incorporated to activate Al reactivity in Al-CuO and Al-MoO3. Flame speeds, differential scanning calorimetry (DSC), and quadrupole mass spectrometry (QMS) were performed for varying percentages of PFPE blended with Al/MoO3 or Al/CuO to examine reaction kinetics and combustion performance. X-ray photoelectron spectroscopy (XPS) was performed to identify product species. Results show that the performance of the thermite-PFPE blends is highly dependent on the bond dissociation energy of the metal oxide. Fluorine-Al-based surface reaction with MoO3 produces an increase in reactivity, whereas the blends with CuO show a decline when the PFPE concentration is increased. These results provide new evidence that optimizing Al combustion can be achieved through activating exothermic Al surface reactions. (Figure Presented).
KW - aluminum fluoride
KW - aluminum powder
KW - combustion
KW - energetic materials
KW - exothermic surface chemistry
KW - fluorine
KW - oligomers
KW - preignition reaction
UR - http://www.scopus.com/inward/record.url?scp=84940403656&partnerID=8YFLogxK
U2 - 10.1021/acsami.5b05238
DO - 10.1021/acsami.5b05238
M3 - Article
AN - SCOPUS:84940403656
VL - 7
SP - 18742
EP - 18749
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
SN - 1944-8244
IS - 33
ER -