DETERMINATION OF IGNITION PROCESSES OF METAL FUEL PARTICLES IN THE DECOMPOSITION PRODUCTS OF PYROTECHNIC MULTICOMPONENT NITRATE-METALLIZED MIXTURES

Abstract

The results of experimental studies of the process of ignition of magnesium in
gaseous products of thermal decomposition of nitrate-containing oxidizers (nitrates of
alkali and alkaline earth metals), additives of organic and inorganic substances that are
part of pyrotechnic multi-component nitrate-metallized mixtures, which precede the
process of development of combustion of mixtures under conditions of external thermal
actions are presented.
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«Надзвичайні ситуації: попередження та ліквідація», Том 8 № 2 (2024)
To prevent premature fire-explosive destruction of products under conditions of
external thermal effects, it is necessary, first of all, to have data on the patterns of the
ignition process of metal fuel particles in gaseous products of thermal decomposition of
oxidants and additives of organic and inorganic substances, which precedes the process
of explosive development of combustion of mixtures under the specified conditions.
In this paper, it was established that at ambient temperatures above the
limiting Тз, vapor-phase ignition was always preceded by surface ignition of
conglomerates.
When studying the effect of alloying elements (Ni, Bi, Zn, Ag, Cu, Sn, Pb, Sb, In,
Al) on the ignition temperature of solid magnesium in dry oxygen, it was established
that the addition of all these metals to a concentration of several percent causes a
decrease in temperature ignition. For example, aluminum lowers the ignition
temperature from 896 K for pure Mg to 776 K with an aluminum content of 18%
(oxygen pressure is 1.013·105 Pa).
Based on these experiments, it was concluded that the value of the ignition
temperature of magnesium alloys is inversely proportional to the linear rate of
oxidation.
The propensity of magnesium to ignite sharply decreases in the presence of 0.5% silicon
fluoride in the atmosphere. At the same time, the presence in the air of 1...0.3% of
silicon fluoride or sulfur dioxide and 1...0.2% of boron fluoride not only prevents
magnesium from igniting, but also stops its burning.