Metal-oxidizer ZPP One of the most common initiators is
ZPP, or
zirconium – potassium perchlorate – a mixture of metallic zirconium and potassium perchlorate. This mixture is used in the
NASA Standard Initiator, which is used to ignite various pyrotechnic systems, including the
NASA standard detonator. It yields rapid pressure rise, generates little gas, emits hot particles when ignited, is thermally stable, has long shelf life, and is stable under vacuum. It is sensitive to
static electricity.
BPN Another common igniter formula is
BPN,
BKNO3, or
boron – potassium nitrate, a mixture of 25%
boron and 75%
potassium nitrate by weight. It is used e.g. by
NASA. It is thermally stable, stable in vacuum, and its burn rate is independent of pressure. In comparison with black powder, BPN burns significantly hotter and leaves more of solid residues, therefore black powder is favored for multiple-use systems. BPN's high temperature makes it suitable for uses where rapid and reproducible initiation is critical, e.g. for
airbags, rocket engines, and
decoy flares. It is however relatively expensive. BPN can be also used as an ingredient of
solid rocket propellants. BPN can be ignited by a laser. A semiconductor laser of at least 0.4 watts output can be used for ignition in vacuum.
Others Other mixtures encountered are
aluminium-
potassium perchlorate and
titanium-aluminium-potassium perchlorate.
Metal hydride-oxidizer Metal hydride-oxidizer mixtures replace the metal with its corresponding
hydride. They are generally safer to handle than the corresponding metal-oxidizer compositions. During burning they also release
hydrogen, which can act as a secondary fuel. Zirconium hydride, titanium hydride, and boron hydride are commonly used.
ZHPP ZHPP (
zirconium hydride – potassium perchlorate) is a variant of ZPP that uses
zirconium hydride instead of pure zirconium. It is significantly safer to handle than ZPP.
THPP THPP (titanium hydride potassium perchlorate) is a mixture of
titanium(II) hydride and potassium perchlorate. It is similar to ZHPP. Like ZHPP, it is safer to handle than titanium-potassium perchlorate.
Nickel-aluminium Nickel-
aluminium laminates can be used as electrically initiated pyrotechnic initiators.
NanoFoil is such material, commercially available.
Palladium-aluminium Palladium-clad
aluminium wires can be used as a
fuse wire, known as
Pyrofuze. The reaction is initiated by heat, typically supplied by electric current pulse. The reaction begins at 600 °C, the melting point of aluminium, and proceeds violently to temperature of 2200–2800 °C. The reaction does not need presence of oxygen, and the wire is consumed. Pyrofuze comes as a solid wire of different diameters (from 0.002" to 0.02"), braided wire, ribbon, foil, and granules. Palladium,
platinum, or palladium alloyed with 5%
ruthenium can be used together with aluminium. Pyrofuze
bridgewires can be used in
squibs and
electric matches. Pyrofuze foils can be used for e.g. sealing of various dispensers or fire extinguishing systems. Palladium-magnesium composition can also be used, but is not commercially available or not at least as common.
Others BNCP BNCP, ('''
cis-bis-(5-nitrotetrazolato)tetraminecobalt(III) perchlorate''') is another common initiator material. It is relatively insensitive. It undergoes
deflagration to
detonation transition in a relatively short distance, allowing its use in
detonators. Its burning byproducts are of relatively little harm to environment. It can be ignited by a
laser diode.
Lead azide Lead azide (Pb(N3)2, or PbN6) is occasionally used in pyrotechnic initiators.
Others Other materials sensitive to heat can be used as well, e.g.
HMTD,
tetrazene explosive, lead mononitro-resorcinates, lead dinitro-resorcinates, and lead trinitro-resorcinates. ==See also==