Al‐Ni‐NiO Pyrotechnic Time‐Delays

Abstract

The time delay elements in conventional mine detonators comprise pyrotechnic compositions pressed in aluminum tubes. Thermite and intermetallic reactions offer the possibility of greener alternatives for current heavy metal-based compositions. Unfortunately, the high reaction temperatures associated with conventional thermites cause operational failures due to the melting of the metal housings. Similarly, it is difficult to achieve sustained burning with intermetallic systems alone. Combination thermite-intermetallic systems may offer a solution to both problems.The concept is illustrated through ternary compositions based on powder mixtures of aluminum, nickel and nickel oxide. Progressive dilution of the primary thermite reaction, 5 Al + 3 NiO!Al 2 O 3 + 3 AlNi, with the intermetallic reaction, Al + Ni!AlNi, smoothly reduced the adiabatic reaction temperature by as much as 800 K simultaneously maintaining consistent burn behavior inside both glass and lead tubes. However, in the process the burning rate gradually decreased from ca. 190 mm s À 1 to as low as 23 mm s À 1 .

Highly Reactive Thermite Energetic Materials: Preparation, Characterization, and Applications: A Review

“…In addition to the method mainly used for designing tEMs, researchers at home and abroad tried to explore other preparation technologies, including arrested reactive milling [ 122 , 123 ], reactive plasma spraying [ 124 ], electrospray deposition [ 125 ], powder metallurgy [ 126 ], the freeze-drying method [ 127 ], the hydrothermal synthesis method [ 128 ] and the brush-mixing technique [ 129 ]. Interestingly, J.M.…”

“…Until now, energetic materials, particularly tEMs, have been extensively reported and fabricated via different preparation methods, owing to their wide range of application, which include the defense industry, detonators [ 128 , 129 , 130 , 131 ], igniters [ 132 , 133 ], gas sensors [ 77 , 134 , 135 , 136 , 137 ], thin-film battery [ 138 ] and chip adhesive [ 139 ]. Beyond that, the design of an all-solid-state lithium/electrolyte interface was realized by inducing an energetic reaction between metal fuel and nitrate, showing high capacity, small overpotential, high efficiency, and a long cycle life [ 140 ].…”

Study of the Combustion Mechanism of Zn/KMnO4 Pyrotechnic Composition

“…Post-combustion residues were produced by combustion of PDC formulations in combustion cell with constant volume of 45 cm 3 . The detailed testing process has been explained in our previous work [16].…”

“…A significant number of PDC formulations have been reported in the literature, including recent reports of formulations such as Mn/Bi 2 O 3 [2], Al/Ni/NiO [3] and even an Al/Si/Bi 2 O 3 , the latter of which is viable as a "pyrotechnic ink" for printing [4]. It should be noted that, despite the favourable properties of these PDCs, they have not found broader application, due to associated issues, such as the relatively high toxicity of Bi 2 O 3 , particularly in the presence of other environmental pollutants [5,6].…”

Sn/Mn/Bi2O3 Ternary Pyrotechnic Time Delay Compositions

“…On the other hand, the exothermicity of intermetallic reactions often proves insufficient to sustain reliable burning in time delay columns. Combining the two approaches may provide a solution to both problems. − The dilution effect posed by the intermetallic component provides the desired reduction in the overall reaction temperature. Furthermore, adding a carefully chosen thermite may boost the exothermicity of the intermetallic, and thereby facilitate reliable burning.…”