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Radiative Ignition of Fine‐Ammonium Perchlorate Composite Propellants
Author(s) -
Cain Jeremy,
Brewster M. Quinn
Publication year - 2006
Publication title -
propellants, explosives, pyrotechnics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.56
H-Index - 65
eISSN - 1521-4087
pISSN - 0721-3115
DOI - 10.1002/prep.200600037
Subject(s) - opacity , ammonium perchlorate , ignition system , materials science , carbon black , absorption (acoustics) , analytical chemistry (journal) , radiative transfer , propellant , chemistry , composite material , composite number , thermodynamics , optics , physics , natural rubber , organic chemistry , chromatography
Radiative ignition of quasi‐homogeneous mixtures of ammonium perchlorate (AP) and hydroxyterminated polybutadiene (HTPB) binder has been investigated experimentally. Solid propellants consisting of fine AP (2 μm) and HTPB binder (~ 76/24% by mass) were ignited by CO 2 laser radiation. The lower boundary of a go/no‐go ignition map (minimum ignition time vs. heat flux) was obtained. Opacity was varied by adding carbon black up to 1% by mass. Ignition times ranged from 0.78 s to 0.076 s for incident fluxes ranging from 60 W/cm 2 to 400 W/cm 2 . It was found that AP and HTPB are sufficiently strongly absorbing of 10.6 μm CO 2 laser radiation (absorption coefficient ≈250 cm −1 ) so that the addition of carbon black in amounts typical of catalysts or opacitymodifying agents (up to 1%) would have only a small influence on radiative ignition times at 10.6 μm. A simple theoretical analysis indicated that the ignition time‐flux data are consistent with in‐depth absorption effects. Furthermore, this analysis showed that the assumption of surface absorption is not appropriate, even for this relatively opaque system. For broadband visible/near‐infrared radiation, such as from burning metal/oxide particle systems, the effects of in‐depth absorption would probably be even stronger.