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Ignition mechanism of the Zr/PbCrO 4 pyrotechnic mixture in presence of an oxidizing atmosphere
Author(s) -
Brassy C.,
Marlin F.,
Roux M.
Publication year - 1994
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.19940190403
Subject(s) - oxidizing agent , diffusion , oxygen , activation energy , zircon , ignition system , materials science , oxide , thermodynamics , phase (matter) , limiting , atmosphere (unit) , analytical chemistry (journal) , chemistry , chemical engineering , metallurgy , organic chemistry , geology , paleontology , physics , engineering , mechanical engineering
In presence of oxygen, the Zr/PbCrO 4 (60%/40%) solid mixture exhibits a high amplitude exothermal reaction at low temperature (before reaching the oxidant decomposition temperature). We assume that the reaction is entertained by the air oxygen which continuously diffuses into the mixture pores. The solid‐phase diffusion of oxygen through a zircon layer seems to constitute the limiting step of the reaction. To verify this assumption, a model allowing for diffusion in a protective oxide is developed. The results obtained with this model correspond to the tests for an apparent energy diffusion value varying between 130 kJ/mol and 170 kJ/mol. A value of 130 kJ/mol corresponds to the migration energy of the anionic gaps in a porous zircon layer. The evolution of the apparent diffusion energy can be attributed to the formation energy of crystalline defects (in particular anionic gaps).